Biomedical subjects

N P Lang

Publications and source records attributed to N P Lang.

At least 19 recordsLinked to original sources

PubMed1999

Development of an antipeptide antibody that binds to the C-terminal region of human CYP1B1.

An antipeptide antibody was raised against a 14-mer synthetic peptide (CDFRANPNEPA KMN) corresponding to the amino acid sequence from 491 to 504 of human cytochrome P-450 (CYP)1B1. Rabbit-derived antisera demonstrated the ability to induce moderately high antibody titers (>1:10(5)) as judged by enzyme-linked immunosorbent assay. In Western blot analysis, the purified antibody recognized a single protein band (estimated as 56 kDa) in microsomes prepared from human and rodent tissues. No significant cross-reactivity to either human CYP1A1 or human CYP1A2 protein was detected. Titration studies using recombinant human CYP1B1 and an enhanced chemiluminescence-based detection method demonstrated a minimal detection sensitivity for this antiserum at about 0.34 ng/band in 8 x 7-cm minigels. The immunoprecipitation and immunoinhibition results indicate that this antisera recognizes the nondenatured human CYP1B1 protein but does not inhibit its enzyme activity. Using this antibody, CYP1B1 protein was detected in nine different human tissues and in cultured cells induced by various chemicals. This highly specific, highly sensitive antibody provides an important tool to study tissue distribution and cellular expression levels of CYP1B1, with negligible cross-reactivity from the other members of the CYP1 family.

Amino Acid Sequence↗

PubMed1998

Identification of enzymes responsible for the metabolism of heme in human platelets.

The major enzymes involved in the degradation of heme were identified in human platelets. It was determined that heme oxygenase activity levels in umbilical cord blood platelets were higher, whereas biliverdin reductase activity levels were comparable with that found in platelets from adults. In membranes prepared from adenosine diphosphate-activated platelets, UDP-glucuronic acid-dependent bilirubin conjugation was detected, whereas activity was negligible in unactivated platelets and undetected in serum and heat-inactivated platelets, and in platelets prepared from umbilical cord blood. Platelet fractions were analyzed by Western blot and shown to express heme oxygenase, biliverdin reductase, and UDP-glucuronosyltransferases, and there was concordance with known developmental profiles found in other tissues. Heme oxygenase expression was higher, whereas UGT expression was lower, in neonatal compared with adult platelets. These data suggest that platelets are involved in multiple steps of heme and bilirubin metabolism and that developmental regulation of these enzymes may be similar to that in other human tissues.

Adult↗

PubMed1998

Comparison of DNA adduct levels associated with oxidative stress in human pancreas.

DNA adducts associated with oxidative stress are believed to involve the formation of endogenous reactive species generated by oxidative damage and lipid peroxidation. Although these adducts have been reported in several human tissues by different laboratories, a comparison of the levels of these adducts in the same tissue samples has not been carried out. In this study, we isolated DNA from the pancreas of 15 smokers and 15 non-smokers, and measured the levels of 1,N6-etheno(2'-deoxy)guanosine (edA), 3, N4-etheno(2'-deoxy)cytidine (edC), 8-oxo-2'-deoxyguanosine (8-oxo-dG), and pyrimido[1,2-alpha]purin-10(3H)-one (m1G). Using the same DNA, the glutathione S-transferase (GST) M1, GSTT1, and NAD(P)H quinone reductase-1 (NQO1) genotypes were determined in order to assess the role of their gene products in modulating adduct levels through their involvement in detoxification of lipid peroxidation products and redox cycling, respectively. The highest adduct levels observed were for m1G, followed by 8-oxo-dG, edA, and edC, but there were no differences in adduct levels between smokers and non-smokers and no correlation with the age, sex or body mass index of the subject. Moreover, there was no correlation in adduct levels between edA and eC, or between edA or edC and m1G or 8-oxo-dG. However, there was a significant correlation (r=0.76; p<0.01) between the levels of 8-oxo-dG and m1G in human pancreas DNA. Neither GSTM1 nor NQO1 genotypes were associated with differences in any of the adduct levels. Although the sample set was limited, the data suggest that endogenous DNA adduct formation in human pancreas is not clearly derived from cigarette smoking or from (NQO1)-mediated redox cycling. Further, it appears that neither GSTM1 nor GSTT1 appreciably protects against endogenous adduct formation. Together with the lack of correlation between m1G and edA or edC, these data indicate that the malondialdehyde derived from lipid peroxidation may not contribute significantly to m1G adduct formation. On the other hand, the apparent correlation between m1G and 8-oxo-dG and their comparable high levels are consistent with the hypothesis that m1G is formed primarily by reaction of DNA with a base propenal, which, like 8-oxo-dG, is thought to be derived from hydroxyl radical attack on the DNA.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1998

Genetic polymorphisms in human liver phenol sulfotransferases involved in the bioactivation of N-hydroxy derivatives of carcinogenic arylamines and heterocyclic amines.

Three related forms of phenol sulfotransferase (PSULT), thermostable ST1A2 (SULT1A2hum) and ST1A3 (SULT1A1hum) and a thermolabile TL-PST (SULT1A3hum), are known to exist in human livers. Thermostable forms, whose activities are polymorphically distributed, have been shown to mediate the bioactivation of carcinogenic N-hydroxy arylamines and heterocyclic amines. To clarify the nature of the sulfation polymorphism, the study compared the expressed levels of ST1A2, ST1A3 and TL-PST mRNAs in human livers by the method of reverse-transcriptase polymerase chain reaction (RT-PCR), utilizing HindIII, BamHI and SnaBI sites which were unique to the above PSULT cDNAs, respectively. Of the PCR products derived from human liver (n = 26), 43-89, < 1-29 and < 1-21% showed the restriction pattern characteristic for ST1A3, ST1A2 and TL-PST cDNAs, respectively, thus indicating that ST1A3 mRNA is the major transcript. Hepatic p-nitrophenol and dopamine sulfation rates ranged from 440-2670 and < 5-460 pmol/min per mg protein in the 26 individuals, respectively. The observed differences in the ST1A3 and TL-PST mRNA levels were consistent with the differences in p-nitrophenol and dopamine sulfations. Relative levels of hepatic ST1A3 mRNA were non-normally distributed and correlated significantly with p-nitrophenol sulfation. In addition, variant forms of ST1A3 mRNA encoding Arg213His and Met223Val were detected in human livers. With regard to Arg213His, 28 individuals who had homozygous 213Arg alleles, 15 individuals who were heterozygotes and nine homozygous 213His individuals were found by a newly established genotyping method among 52 human liver samples. Frequency of 223Val allele was apparently lower than that of 213His allele, as no homozygous 223Val individual and only three individuals who were heterozygotes (223Met/Val) were observed among 52 individuals. These results suggest that regulation of p-nitrophenol sulfation occurs at the level of gene transcription of ST1A3 which is the major transcript of the three PSULT mRNAs and that a polygenic basis for the apparent genetic polymorphism of sulfation was likely because of the existence of ST1A3 variants.

Amines↗

PubMed1998

Identification of communication apprehension in medical students starting a surgery rotation.

BACKGROUND: Most methods used to critically evaluate young surgeons for advancement or certification in surgery require oral communication skills, eg, case and research presentations, rounds, morbidity and mortality conferences, interviews, journal clubs and oral examinations. The irony, though, is that much of surgery training focuses on technical skill lists, and the rhetorical aspects are often neglected until the surgeon encounters failure in an oral examination or is sued for not "talking" appropriately. Early identification of those at risk for difficulty with oral skills would provide programs with time needed to arrange for the appropriate types of interventions. Therefore, the purpose of this study was to identify those medical students with high communication apprehension scores in dyadic, group, or public speaking situations before they encountered failure and caused problems, not only for themselves, but also for their programs and practices. METHODS: Two scales, Willingness to Communicate (WTC) and the Personal Report of Communication Apprehension (PRCA-24), were administered to medical students at two large university medical centers during new student orientation to the surgery rotation. The WTC is a 20-item probability-estimate scale designed to measure one's predisposition toward approaching or avoiding the initiation of communication. The PRCA-24 is a scale designed to measure one's fear associated with either real or anticipated communication in four different contexts. In addition to the 44 items, a lengthy list of demographic items was added for possible correlations. These items were based on the student's perception of the communication or language environment in which he was raised. Therefore, a student ranked past and future socioeconomic status (eg, blue collar or white collar) according to his or her own criteria. The chairman was provided with a list of individual scores. Those students who were below the group means on skills required during a surgery rotation were identified for immediate intervention. RESULTS: The published data show a norm mean of 65.6 for PRCA-24 and 65.2 for WTC for college students. The current study found medical students to be more willing to communicate (WTC) and less anxious about communication (PRCA-24) than college students (mean 70.7 versus 65.2, P = 0.003, and 61.6 versus 65.6, P = 0.01, respectively). This difference was accentuated for blue-collar medical students compared with college students and persisted when blue-collar medical students were compared with white-collar medical students (73.9 blue-collar versus 70.9 college students, P = 0.15 for WTC, and 58.5 blue-collar versus 63.6 white-collar, P = 0.002 for PRCA-24). Male medical students were found to be less anxious about communication than female medical students. CONCLUSIONS: These instruments are easily administered at orientation and produce simple class lists with individual scores. They can be used to identify students who are below the mean for specific forms of communication before they encounter failure.

Clinical Clerkship↗

PubMed1998

Evaluation of postsurgical crestal bone levels adjacent to non-submerged dental implants.

In most of the studies on long-term radiographic evaluations of crestal bone levels adjacent to dental implants, no baseline radiographs taken immediately postsurgically had been obtained. The aim of this study was to test the reproducibility of a simple radiographic method for linear measurements of changes in bone levels and to evaluate changes in crestal bone levels adjacent to non-submerged ITI implants 1 year following the surgical procedure. From 128 patients enrolled in a clinical and radiographic longitudinal study 40 patients also had radiographs taken immediately postsurgically. They were, however, not obtained as "identical" images. The radiographs were mounted onto slides and projected on a screen. Mesially and distally from 57 implants triplicate linear measurements of the distance implant shoulder to bone crest were taken, using known dimensions of the implants as internal reference distances. The median difference of 213 (out of 228 possible) duplicate measurements was 0.00 mm (ranging from -1.72 mm to +1.47 mm when comparing the second to the third reading). Some 81% of the double measurements were within +/- 0.5 mm and the precision was 0.30 mm. In the immediate postoperative radiographs the median mesial bone level was located at 2.07 mm (distally 2.19 mm) from the implant shoulder. A statistically significant amount of bone loss in the first year was observed mesially (median = -0.78 mm) and distally (-0.85 mm) (Wilcoxon matched pairs signed rank test P < or = 0.001). No statistically significant influence of the implant location, the implant length, type of the implant (screw; cylinder) was observed (Kruskal-Wallis P > 0.05). The age of the patients was not correlated significantly to the amount of bone loss observed. In conclusion, methodological limitations existed when evaluating linear bone changes in non-identical radiographs using reference dimensions of the implants. The amount of postsurgical bone loss estimated in other studies was confirmed when using an immediate postoperative radiograph as a baseline.

Adolescent↗

PubMed1998

Bone-to-implant contact of orthodontic implants in humans subjected to horizontal loading.

Implant-based anchorage in orthodontics is increasingly obtaining significance. In this study, implants were temporarily inserted into the mid-palatal and the mandibular retromolar areas in humans for orthodontic anchorage. Histological analysis of the implant-bone interface was performed following the retrieval of implants which were subjected to prolonged oblique orthodontic loading. The results of the histomorphometric evaluation indicated that all the implants serving for orthodontic anchorage were well integrated into the bone despite the prolonged application of the orthodontic loading. Hence, it may be concluded that small-size, one-part transmucosal implants with a self-tapping thread and an SLA surface seemed to provide adequate anchorage for orthodontic therapy. Furthermore, the successful integration and the subsequent oblique loading of these orthodontic implants provide evidence that continuous forces in the order of magnitude of 2-6 N are compatible with the maintenance of osseointegration.

Adolescent↗

PubMed1998

Metabolic activation of methyl-hydroxylated derivatives of 7,12-dimethylbenz[a]anthracene by human liver dehydroepiandrosterone-steroid sulfotransferase.

Methyl-hydroxylated metabolites of the potent carcinogen, 7,12-dimethylbenz[a]anthracene (DMBA), namely, 7-hydroxymethyl-12-methylbenz[a]anthracene (7-OH-DMBA), 7-methyl-12-hydroxymethylbenz[a]anthracene (12-OH-DMBA) and 7,12-dihydroxymethylbenz[a]anthracene (7,12-diOH-DMBA), were examined as substrates for sulfotransferase bioactivation in different human tissue cytosols. Hepatic cytosols, which were able to catalyze the 3'-phosphoadenosine 5'-phosphosulfate (PAPS)-dependent DNA binding of 7-OH-DMBA, 12-OH-DMBA and 7,12-diOH-DMBA, were highly sensitive to inhibition by dehydroepiandrosterone (DHEA), a specific substrate for human DHEA-steroid sulfotransferase (IC50 = 5 microM). By comparison, 2,6-dichloro-4-nitrophenol, a potent inhibitor of the thermostable (TS)-phenol and estrogen sulfotransferases, did not have an appreciable inhibitory effect. Neither p-nitrophenol, a high affinity substrate for human TS-phenol and estrogen sulfotransferases, nor dopamine, a specific substrate for the thermolabile (TL)-phenol sulfotransferase, significantly inhibited the DNA binding of 12-OH-DMBA catalyzed by hepatic cytosols. Inter-subject variation (n = 12) of the PAPS-dependent DNA binding of 12-OH- and 7,12-diOH-DMBAs also correlated well with DHEA-sulfotransferase activity (r = 0.90; P < 0.00001 and r = 0.92; P < 0.00001, respectively). This sulfation-dependent metabolic activation was not detected in cytosols from human colon, pancreas, larynx or mammary gland. Both TS- and TL-phenol sulfotransferases were active in human liver and colon but only liver contained DHEA-sulfotransferase activity. These results indicate that the sulfotransferase-mediated activation of the methyl-hydroxylated DMBAs is predominantly catalyzed by DHEA-steroid sulfotransferase in human liver and that TS- and TL-phenol sulfotransferases and estrogen sulfotransferase are not involved in the catalysis.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1998

Changes in the prevalence of residual pockets and tooth loss in treated periodontal patients during a supportive maintenance care program.

Bleeding on probing and the presence of deep periodontal pockets are considered to be the best site-specific indicators for periodontal disease progression during the maintenance phase of periodontal therapy. A major emphasis of supportive periodontal care (SPC) programs, therefore, has been the control of bleeding pockets. This investigation retrospectively evaluated the changes in the prevalence of bleeding on probing, periodontal pockets, bleeding periodontal pockets and the prevalence of tooth loss in a random sample of 273 periodontal patients participating in a supportive maintenance care program at a University Clinic. During an observation period of 67+/-46 months (range 5 months to 23 years), the overall incidence of all causes of tooth mortality was 0.23+/-0.49 teeth per patient per year of observation. 56% of subjects, however, did not experience any tooth loss, while less than 10% of patients lost more than 3 teeth. Thus, participation in the SPC program was effective in preventing tooth loss in the majority of patients. During the SPC period, however, a significant increase in the prevalence of periodontal pockets, and of bleeding on probing positive periodontal pockets, in particular, was observed. At completion of active periodontal therapy, 56.4% of patients were free from bleeding pockets. This decreased to a mere 13.6% at the latest SPC evaluation. The observed increases in the number of bleeding pockets was significantly associated with: longer times since completion of active periodontal therapy, more advanced periodontal diagnosis, higher %s of bleeding sites in the dentition, cigarette smoking, lack of inclusion of periodontal surgery in the active treatment phase, tooth loss, and the response to the active phase of periodontal treatment. The data presented in the paper indicate that the observed increase in the prevalence of bleeding pockets and tooth loss was not homogeneously distributed in the studied SPC population. Rather, high risk groups of individuals could be identified. It is suggested that better knowledge of risk indicators may lead to improved and more efficient risk management efforts during periodontal maintenance care.

Adolescent↗

PubMed1998

Evaluation of tetracycline fiber therapy with digital image analysis.

The aims of the present study were to assess radiographically the effects of scaling/root planing combined with antibiotic therapy using tetracycline fibers (TCF): (I) on alveolar bone density and linear descriptors and (II) on supracrestal soft tissue density. 19 subjects with generalized adult periodontitis (with at least 20 teeth present, at least 4 teeth with pockets >4 mm and bleeding upon controlled force probing) and high cultural counts of Porphyromonas gingivalis were recruited from a pool of 57 patients. The full mouth treatment group (FT) consisted of 10 patients, who underwent a full mouth supra-gingival scaling and prophylaxis treatment and were instructed to rinse 2x daily with a 0.1% chlorhexidine solution. 1 week later, tetracycline-hydrochloride-containing fibers (Actisite periodontal fiber) were applied around all teeth. After 7-12 days, the fibers were removed and all teeth were scaled and root planed under local anaesthesia. The chlorhexidine rinsing continued for another 2 months. In 9 subjects (local treatment group LT), 2 teeth with periodontal lesions with pocket probing pepth (PPD) > or =5 mm were treated by placement of tetracycline fibers, which remained in place for 7 to 12 days. Upon removal of the fibers, scaling and root planing was performed on these 2 teeth, while the rest of the dentition remained untreated, and no chlorhexidine rinse was applied. 2 of the untreated teeth revealing similar periodontal lesions were chosen to represent sites affected by untreated periodontitis (NT). In this group, a limited local treatment was performed (2 teeth) with the inherent potential for recolonization from the untreated pocket sites. Standardized periapical radiographs were obtained from the 4 monitored sites within each patient at baseline (before treatment) and 2 and 6 months thereafter. One radiograph was exposed in a standard way for bone assessment. The second radiograph was underexposed, at about a 1/5 of the original exposure time to allow the evaluation of soft tissue. Mean changes in the linear parameters and changes in density (CADIA) observed at multiple sites within each patient and treatment group were used as the best estimate of treatment outcome. Over the observation period of 6 months, a significant difference in bone height changes was found between the untreated sites (median loss -0.29 mm) and the sites from full-mouth treated patients (median gain 0.24 mm, p=0.008). When comparing the baseline to the 6 months radiographs, a loss in bone density was observed for the untreated group (median=-2.13 CADIA). Both treatment groups revealed a gain in density (median=1.58 and 2.43 CADIA for the locally and the full-mouth treated groups, respectively). Differences in density were significant, both between the nontreated and locally treated sites (p=0.026) and between the nontreated sites and the sites from the full mouth treated patients (p=0.002). The analysis of the soft tissues showed a similar pattern of changes in density to those seen in the bone defect. At 2 months, there was a tendency for loss in density for the nontreated group (median=-0.17 CADIA) that continued over the 6 month period (median=-0.31 CADIA). A significant increase in density was observed for the full-mouth treated sites (median=1.57 and 0.64 CADIA for the 2 and 6 months radiographs, respectively). A significant increase was also observed for the locally treated group when compared to the untreated sites (median=0.13 and 0.10 CADIA for the 2 and 6 months radiographs, respectively). Comparing untreated sites with full-mouth treated sites, a significant difference was observed for CADIA measurements (p<0.001). No significant difference was observed comparing locally treated and untreated sites (p=0.24). It was concluded that scaling and root planing combined with TCF therapy can result in increased bone density and alveolar bone height. Full-mouth treatment seemed to result in more pronounced gains compared to local tre

Adult↗

PubMed1998

Plaque formation and gingivitis after supervised mouthrinsing with 0.2% delmopinol hydrochloride, 0.2% chlorhexidine digluconate and placebo for 6 months.

OBJECTIVES AND METHODS: A double-blind, randomized, 6-month clinical trial with parallel group design in 162 patients with gingivitis divided into three rinsing groups was conducted in order to study the efficacy and safety of a flavoured solution of delmopinol hydrochloride 2 mg ml-1 (0.2% w/v, Decapinol Mouthwash) used for supervised mouthrinsing in one rinsing group, in comparison with chlorhexidine digluconate 2 mg ml-1 (0.2% w/v, Hibitane Dental) in a second rinsing group, and placebo in the third group. The criteria of the Plaque Index (PI) were used to assess plaque formation. Bleeding on probing (BOP) to the bottom of the pocket with a standard pressure was used as the primary gingivitis assessment. The occurrence of supragingival dental calculus and extrinsic tooth staining were also assessed. In addition, patients were asked to report adverse events at each visit. RESULTS: Delmopinol and chlorhexidine exhibited lower scores of the mean PI and the BOP percentage than placebo, both at the 3-month and 6-month examinations. Furthermore, both active solutions showed a higher extent of staining of the teeth than placebo during these two observation periods. Rinsing with chlorhexidine resulted in more dental calculus than placebo after 6 months. Chlorhexidine showed lower scores for plaque formation and gingivitis development but higher scores of supragingival dental calculus (after 6 months) and tooth staining than did delmopinol. Both active solutions were reported by the patients--approximately to the same extent but more frequently than placebo--to induce taste alterations and a transient anaesthetic sensation of the oral mucosa. However, subjective staining of the teeth and tongue was reported by 16% of the delmopinol patients, but by 86% of the patients rinsing with chlorhexidine for 6 months. Furthermore, 24% of the patients in the chlorhexidine group, 9% in the delmopinol group and 4% in the placebo group wished to withdraw from treatment. CONCLUSIONS: The results from this clinical trial indicate that supervised rinsing with 0.2% delmopinol hydrochloride or with 0.2% chlorhexidine digluconate twice daily for 60 s as a supplement to normal mechanical oral hygiene procedures resulted in less plaque formation and gingivitis than rinsing with placebo. Although chlorhexidine was more effective than delmopinol regarding plaque formation and gingivitis, it was considered by the patients as less tolerable.

Adult↗

PubMed1998

In situ detection of apoptosis at sites of chronic bacterially induced inflammation in human gingiva.

Apoptosis is a key phenomenon in the regulation of the life span of terminally differentiated leukocytes. Human gingiva represents an established model to study immune responses to bacterial infection. In this investigation, we used the TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) technique to evaluate presence and topographic location of apoptosis-associated DNA damage in human gingival biopsies along with the expression of the p53 and Bcl-2 apoptosis-regulating proteins. Qualitative data analysis showed high densities of cells expressing DNA damage and p53 both within the epithelial attachment to the tooth and in the perivascular infiltrate (infiltrated connective tissue [ICT]) immediately underlying the site of chronic bacterial aggression. Topographic consistency between DNA damage- and p53-positive cells was consistently observed. Quantitative analysis of the ICT showed mean densities of DNA damage- and p53-positive cells of 345 +/- 278 and 403 +/- 182 cells/mm2, respectively. Numerical consistency was confirmed by multivariate regression analysis: densities of DNA damage-positive cells were significantly predicted by densities of p53-positive cells (P = 0. 001, r2 = 0.84). In the ICT, cells displaying biotinylated DNA nicks were 3.8% +/- 2.7% of total cellularity, while p53- and Bcl-2-positive cells represented 4.4% +/- 1.7% and 15.4% +/- 6.7% of total cells, respectively. It is suggested that p53 expression associated with DNA damage is a prevalent phenomenon in chronically inflamed human gingiva, and that apoptosis may be a relevant process for the maintenance of local immune homeostasis at sites of chronic bacterial challenge in vivo.

Apoptosis↗

PubMed1998

Neutrophil migration into the gingival sulcus is associated with transepithelial gradients of interleukin-8 and ICAM-1.

The expression of adhesion molecules and the local production of chemotactic cytokines within the epithelium are considered to be key events in neutrophil (PMN) migration at sites of mucosal infections. In their journey toward the gingival sulcus, PMNs have been shown to selectively migrate through the junctional epithelium. Little, however, is known about the molecular mechanisms involved in this key process aimed at the control of subgingival bacterial plaque. This investigation describes the expression of IL-8 mRNA-positive cells and the establishment of a gradient of intercellular adhesion molecule-1 (ICAM-1) receptors within the junctional epithelium of clinically healthy gingiva. Expression of ICAM-1 and IL-8 was topographically associated with the area of PMN migration; i.e., the junctional epithelium. Levels of ICAM-1 expression increased from the basal cells toward the surface of the junctional epithelium and thus toward areas exposed to bacterial challenges. IL-8 mRNA-positive cells were also present at highest density in the most superficial junctional epithelial layers. The combination of the haptotactic stimuli, resulting from the interaction of the PMN's beta2 integrin receptors with the gradient of ICAM-1 expression, and the location of IL-8 mRNA-positive cells, consistent with the establishment of a discrete PMN chemotactic source, may play an important physiologic role in efficiently routing PMNs to the gingival sulcus. This process contributes to the maintenance of a local host-parasite equilibrium and to the limitation of PMN-associated tissue damage.

CD18 Antigens↗

PubMed1998

Generalizability of the added benefits of guided tissue regeneration in the treatment of deep intrabony defects. Evaluation in a multi-center randomized controlled clinical trial.

BACKGROUND: Several studies have shown that GTR therapy of intrabony defects results in significantly better outcomes than access flap alone. Most of the available data, however, have been produced in highly controlled research environments by a small group of investigators. Generalizability of results to different clinicians and different subject populations has not been evaluated so far. METHODS: This parallel group study involved 143 patients recruited in a practice-based research network of 11 offices in 7 countries. It was designed to evaluate: 1) the applicability of the documented added benefits of GTR in the treatment of intrabony defects to different populations, and 2) the generalizability of the expected results to different clinicians. GTR was compared to access flap alone. Defects, one in each patient, were accessed with a previously described papilla preservation flap in both the test and control group. In addition, GTR sites received application of a bioabsorbable poly-D,L-lactide-co-glycolide membrane. A stringent plaque control regimen was enforced in all patients during the 1-year observation period. Outcomes included gains in clinical attachment (CAL) and reductions in probing depth. RESULTS: Observed gains in CAL were 2.18 +/- 1.46 mm for access flap and 3.04 +/- 1.64 mm for the GTR-treated group. The treatment-associated difference was statistically significant (P = 0.03) after correcting for both center effect and defect anatomy. Among the various centers, a 1.73 mm difference in CAL gain was observed. This is a clinically relevant amount, which underlines the significance of center variability in the outcome of periodontal surgical procedures. A frequency distribution analysis of the obtained CAL gains indicated that GTR treatment of deep intrabony defects decreased, with respect to the access flap control, the probability of obtaining only a modest attachment gain at 1 year. Conversely, CAL gains of 4 mm or more were observed in more than 40% of GTR-treated defects and in less than 20% of the controls (P < 0.0001). CONCLUSIONS: These data indicate that GTR therapy of deep intrabony defects performed by different clinicians on various patient populations resulted in both greater amounts and improved predictability of CAL gains than access flap alone.

Absorbable Implants↗

PubMed1998

Computer-assisted densitometric image analysis of digital subtraction images: in vivo error of the method and effect of thresholding.

The aim of the present study was to assess the in vivo error of the method as well as the effect of thresholding when obtaining and evaluating standardized periapical radiographs for computer-assisted densitometric image analysis (CADIA). Twenty healthy volunteers participated in an experimental gingivitis study in which neither mechanical nor chemical plaque control was performed for 21 days. Two pairs of standardized periapical radiographs were taken at days 0 (baseline) and 21 (follow-up), one from a maxillary area (15 volunteers) and one from a mandibular molar/premolar area (17 volunteers). Each baseline radiograph was digitized and its image displayed on a monitor. The follow-up radiograph was then superimposed and digitized as well. After gray level correction, subtraction radiographic images were produced. The difference in gray level between the baseline and the follow-up image was calculated within each region of interest (ROI) at each picture point (pixel). In bone ROI, changes in density reflected the amount of change due to methodological errors plus the basic bone remodeling over 3 weeks. For gingival ROI, changes in density reflected the methodological error plus a possible change in soft tissue density during the experimental gingivitis. Within all of the ROI, some pixels indicated a change in gray level. A change in gray level was then thresholded; i.e., only changes >5 and then >10 gray levels were registered and used for calculation of the CADIA values. With a threshold of 5, 44/45 maxillary bone ROI and 60/66 mandibular bone ROI showed a change in density, while 41/45 maxillary gingiva ROI and 26/66 mandibular gingiva ROI indicated a change in density. With a threshold of 10, 16/45 maxillary bone ROI and 12/66 mandibular bone ROI indicated a change in density, while 13/45 maxillary gingiva ROI and 1/66 mandibular gingiva ROI indicated a change. The amounts of changes in density calculated in the various ROI were low even when applying no threshold, ranging from -0.279 to 0.621. Applying a threshold of 5, the CADIA values ranged from -0.234 to 0.727. With a threshold of 10, the changes in density ranged from -0.318 to 0.133. In vivo, CADIA of standardized radiographs indicated change in density due to methodological errors. Application of thresholds may avoid false-positive diagnoses. When applying CADIA in clinical research, the range of change to be expected due to methodological limitations as well as the threshold for true change should be evaluated. These thresholds may differ in various areas of the mouth, i.e., bone or gingival, maxillary/mandibular, anterior/posterior ROI.

Absorptiometry, Photon↗

PubMed1997

Immunochemical, 32P-postlabeling, and GC/MS detection of 4-aminobiphenyl-DNA adducts in human peripheral lung in relation to metabolic activation pathways involving pulmonary N-oxidation, conjugation, and peroxidation.

4-Aminobiphenyl (ABP) is a recognized human bladder carcinogen, whose presence in cigarette smoke results in DNA adduct formation in the human urothelium. Since preliminary studies indicated that even higher levels of ABP-DNA adducts may be present in human peripheral lung, we utilized a sensitive immunochemical assay, in combination with 32P-postlabeling, to quantify the major 4-aminobiphenyl (ABP)-DNA adduct, N-(guan-8-yl)-ABP, in surgical samples of peripheral lung tissue from smokers and ex-smokers. No differences in adduct levels were detected between smokers and ex-smokers by immunoassay. In contrast, the 32P-postlabeling method showed statistically significant differences between adduct levels in smokers and ex-smokers; however, a relatively high background of smoking-related adducts chromatograph near the major ABP adducts and may compromise estimation of the level of ABP-DNA adducts in smokers. Furthermore, the levels measured by 32P-postlabeling were 20- to 60-fold lower than that measured by immunoassay. Since 32P-postlabeling may underestimate and immunochemical assays may overestimate adduct levels in the lung, selected samples were also evaluated by GC/MS. The immunochemical and GC/MS data were concordant, leading us to conclude that N-(guan-8-yl)-ABP adducts were not related to smoking status. Since ABP-DNA adduct levels in human lung did not correlate with smoking status as measured by immunoassay and GC/MS, the metabolic activation capacity of human lung microsomes and cytosols was examined to determine if another exposure (e.g., 4-nitrobiphenyl) might be responsible for the adduct. The rates of microsomal ABP N-oxidation were below the limit of detection, which was consistent with a lack of detectable cytochrome P4501A2 in human lung. N-Hydroxy-ABP O-acetyltransferase (but not sulfotransferase) activity was detected in cytosols and comparative measurements of N-acetyltransferase (NAT) using p-aminobenzoic acid and sulfamethazine indicated that NAT1 and NAT2 contributed to this activity. 4-Nitrobiphenyl reductase activity was found in lung microsomes and cytosols, with the reaction yielding ABP and N-hydroxy-ABP. Lung microsomes also demonstrated high peroxidative activation of ABP, benzidine, 4,4'-methylene-bis(2-chloroaniline), 2-aminofluorene, and 2-naphthylamine. The preferred co-oxidant was hydrogen peroxide and the reaction was strongly inhibited by sodium azide but not by indomethacin or eicosatetraynoic acid, which suggested the primary involvement of myeloperoxidase rather than prostaglandin H synthase or lipoxygenase. This was confirmed by immunoinhibition and immunoprecipitation studies using solubilized human lung microsomes and antisera specific for myeloperoxidase. These data suggest that ABP-DNA adducts in human lung result from some environmental exposure to 4-nitrobiphenyl. The bioactivation pathways appear to involve: (1) metabolic reduction to N-hydroxy-ABP and subsequent O-acetylation by NAT1 and/or NAT2; and (2) metabolic reduction to ABP and subsequent peroxidation by myeloperoxidase. The myeloperoxidase activity appears to be the highest peroxidase activity measured in mammalian tissue and is consistent with the presence of neutrophils and polymorphonuclear leukocytes surrounding particulate matter derived from cigarette smoking.

Acyltransferases↗

PubMed1997

Chemoprotection against the formation of colon DNA adducts from the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in the rat.

The mutagenic heterocyclic aromatic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), is a pyrolysis product in cooked foods that has been shown to be a rat colon carcinogen and has been implicated in the etiology of human colon cancer. In order to identify chemoprotection strategies that could be carried out in humans, a pilot study was conducted in which PhIP-DNA-adduct levels were quantified in the colons of male F344 rats that had been subjected to 16 different putative chemoprotection regimens, followed by a gavage of PhIP (50 mg/kg) and sacrifice 24 h later. The 16 treatments (Oltipraz, benzylisothiocyanate, diallyl sulfide, garlic powder, ethoxyquin, butylated hydroxyanisole, glutathione, indole-3-carbinol, alpha-angelicalactone, kahweol/cafestol palmitates, quercetin, green tea, black tea, tannic acid, amylase-resistant starch, and physical exercise) comprised sulfur-containing compounds, antioxidants, flavonoids, diterpenes, polyphenols, high dietary fiber, etc. The strongest inhibition of PhIP-DNA adduct formation in the colon was observed upon pretreatment with black tea, benzylisothiocyanate, and a mixture (1:1) of kahweol:cafestol palmitates, which resulted in 67, 66, and 54% decreases in colon PhIP-DNA adduct levels, as compared with controls. Preliminary studies on their mechanism of action indicated that only kahweol:cafestol caused a substantial induction of glutathione S-transferase isozymes (GSTs) that are thought to be important in the detoxification of PhIP. Notably, this induction occurred in the liver rather than in the colon.

Animals↗

PubMed1997

Polymorphisms of CYP1A1 and GSTM1 influence the in vivo function of CYP1A2.

Differences in human cancer susceptibility have been attributed to polymorphisms of carcinogen metabolizing enzymes. Our efforts have focused on the systems responsible for metabolism of aromatic and heterocyclic amines found in cigarette smoke and in cooked foods. Cytochrome P4501A2 (CYP1A2), which catalyzes aromatic and heterocyclic amine N-oxidation, has been implicated as a risk factor in both urinary bladder and colorectal cancer. In the present study we used the results of caffeine phenotyping experiments to measure the effects of cigarette smoke and compounds present in meat cooked at high temperature on CYP1A2 activity. Subjects in the smoking cessation study had mean CYP1A2 activity of 17.8 (expressed as the urinary molar ratio of [17X + 17U]/137X) while smoking: however, this activity decreased to 10.9 three weeks after cessation of smoking. Subjects in the cooked meat feeding study had mean CYP1A2 activity of 9.01 after 1 week of consuming meat cooked at low temperature, but this value increased to 12.7 after 1 week of consuming meat cooked at high temperature. Because no association has been identified between differences in CYP1A2 activity and variations in the CYP1A2 structural gene, we sought to determine whether the activities of other carcinogen metabolizing enzymes are involved in the regulation of CYP1A2 activity. CYP1A2 activity was higher in individuals who express the GSTM1 null allele compared to those expressing the GSTM1*A,B allele, 10.2 vs. 8.5 for unexposed conditions and 15.0 vs. 12.3 for exposed conditions. CYP1A1 genotyping demonstrated that individuals possessing the Ile/Ile CYP1A1 genotype had greater mean CYP1A2 activity than those who had the heterozygous Ile/Val allelic variant of the CYP1A1 gene. However, upon exposure to cigarette smoke or high-temperature cooked meat, individuals possessing the heterozygous form of the CYP1A1 gene had significantly increased CYP1A2 activity (18.1) compared to those with the more common Ile/Ile CYP1A1 genotype (13.3). These results indicate that CYP1A2, CYP1A1, and GSTM1 gene-gene interactions could be important confounders in the interpretation of molecular epidemiology studies.

Arylamine N-Acetyltransferase↗