Biomedical subjects

C P Chung

Publications and source records attributed to C P Chung.

At least 19 recordsLinked to original sources

PubMed2006

Work disability in early rheumatoid arthritis: higher rates but better clinical status in Finland compared with the US.

OBJECTIVE: To analyse and compare work disability attributed to rheumatoid arthritis in two cohorts of patients with early disease: one in the US and the other in Finland. PATIENTS AND METHODS: Two cohorts of patients who were working and aged <65 years at the time of their first symptom of rheumatoid arthritis were studied: 269 patients in Nashville, TN, USA (median age 46 years, 72.5% females), and 364 patients from Jyväskylä, Finland, (median age 47.1 years, 70.9% females). The cohorts were analysed and compared for measures of clinical status and work disability status over a median (interquartile range) of 38.9 months in Nashville and 48.4 months in Jyväskylä. RESULTS: The probability of working at 36 months was 0.89 (0.84-0.92) for patients from Nashville and 0.84 (0.80-0.88) for patients from Jyväskylä (p = 0.02). These rates were lower than in earlier decades. Patients from Jyväskylä had significantly higher rates of work disability (p = 0.02) than those from Nashville, but better scores for self-report physical function (p<0.001), pain (p<0.001) and global status (p<0.001) at last observation. The likelihood of being disabled from work was 2.6-fold higher in Jyväskylä compared to Nashville (95% confidence interval 1.44 to 4.59, p = 0.001), after adjustment for demographic and disease-specific variables. CONCLUSION: Rates of work disability in both early rheumatoid arthritis cohorts were improved from earlier decades, but differed significantly in two different social systems. Higher work disability rates with better clinical status was seen in the Finnish early rheumatoid arthritis cohort than in the US cohort.

Adult↗

PubMed2006

Are American College of Rheumatology 50% response criteria superior to 20% criteria in distinguishing active aggressive treatment in rheumatoid arthritis clinical trials reported since 1997? A meta-analysis of discriminant capacities.

OBJECTIVE: To carry out a meta-analysis designed to compare the discriminant capacities of American College of Rheumatology 50% (ACR50) with 20% (ACR20) responses in clinical trials on rheumatoid arthritis reported after 1997 and to analyse whether ACR50 can be as informative as ACR20 in distinguishing active from control treatments in more recent trials. METHODS: Clinical trials on rheumatoid arthritis reported since 1997 were identified, which included aggressive combinations of disease-modifying antirheumatic drugs and glucocorticoids, as well as powerful new agents-leflunomide, etanercept, infliximab, anakinra, adalimumab, abatacept, tacrolimus and rituximab. A meta-analysis of ACR20 compared with ACR50 responses for 21 clinical trials was carried out on differences in proportions of responders for active and control treatments and corresponding odds ratios (ORs). RESULTS: In all but one clinical trial on rheumatoid arthritis published since 1997 with data available on ACR20 and ACR50, more than 50% of patients who were ACR20 responders among those randomised to active treatment were also ACR50 responders. This phenomenon was seen for control groups in 38% of trials, many of which included treatment with methotrexate. A meta-analysis of the clinical trials indicated a slight advantage to ACR50 for quantifying treatment comparisons, not significant for differences in proportions but significant for ORs. CONCLUSION: ACR20 and ACR50 seem to be similar in distinguishing active from control treatments in clinical trials on rheumatoid arthritis reported since 1997. As ACR50 represents a considerably stronger clinical response, ACR50 may be a preferred end point for contemporary clinical trials on rheumatoid arthritis.

Antirheumatic Agents↗

PubMed2006

Cardiovascular risk scores and the presence of subclinical coronary artery atherosclerosis in women with systemic lupus erythematosus.

The Framingham risk score is widely used to identify patients at increased cardiovascular risk, and women with systemic lupus erythematosus (SLE) have a marked increased prevalence of cardiovascular events. Thus, we examined the hypothesis that cardiovascular risk scores would identify women with SLE who had asymptomatic coronary atherosclerosis. Ninety-three women with SLE and 65 control subjects were studied. The Framingham score and a score for younger populations developed from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study were compared in both groups. Coronary atherosclerosis was ascertained by electron beam computed tomography. There were no significant differences in the median (interquartile range) Framingham [5 (2-10) compared to 7 (0-10), P = 0.88] and PDAY [15 (14-18) compared to 16 (13-18), P = 0.99] scores in patients with SLE and controls, respectively. Coronary atherosclerosis was associated with higher Framingham [12 (3-15) compared to 4 (1-8), P = 0.008] and PDAY [17 (15-19 compared to 15 (12-18), P = 0.03)] scores in patients with SLE; however, 99% of patients were classified as low-risk with a 10-year predicted risk of 1% (<1-3%). Our data indicate that cardiovascular risk scores are not adequate for risk stratification in women with SLE. Measurement of coronary calcification may add information to identify asymptomatic women with lupus who might benefit from aggressive preventive measures.

Adult↗

PubMed2005

Declines in number of tender and swollen joints in patients with rheumatoid arthritis seen in standard care in 1985 versus 2001: possible considerations for revision of inclusion criteria for clinical trials.

OBJECTIVE: To analyse tender and swollen joint counts in three cohorts of patients with rheumatoid arthritis (RA), with a focus on the proportions of patients who had fewer than 6-12 tender or swollen joints, as possible evidence based information toward more generalisable inclusion criteria for current and future RA clinical trials. METHODS: Tender and swollen joint counts were analysed in three cohorts of patients with RA: 125 in 1985, 138 in 2000, and 232 with early RA in 2001. RESULTS: The median numbers of tender joints were 11, 2, and 4 in 1985, 2000, and in early RA in 2001, respectively. The median numbers of swollen joints were 12, 6, and 5 in 1985, 2000, and 2001, respectively. The numbers of tender joints among 28 assessed were >or=12, >or=6, >or=4, and >or=3 in 47%, 80%, 85%, and 90% of patients in 1985; 20%, 37%, 44%, and 49% in 2000; and 17%, 37%, 50%, and 58% in early RA in 2001. The numbers of swollen joints among 28 assessed were >or=12, >or=6, >or=4, and >or=3 in 51%, 78%, 86%, and 90% of patients in 1985; 20%, 50%, 64%, and 67% in 2000; and 14%, 46%, 58%, and 72% in 2001. The number of patients with >or=6 tender or swollen joints in 1985 was greater than the number with >or=3 joints in 2000 and in early RA in 2001. CONCLUSION: Contemporary cohorts of patients seen in standard care have smaller numbers of tender and swollen joints than in previous times. These findings suggest that revision of inclusion criteria for numbers of tender and swollen joints in contemporary RA clinical trials might improve generalisability.

Adult↗

PubMed2004

The relationship between non-cognitive symptoms and functional impairment in Alzheimer's disease.

OBJECTIVE: Cognitive impairment is an important determinant for functional impairment in Alzheimer's disease. The role of non-cognitive symptom is uncertain. The objective of this study was to investigate the role of non-cognitive symptoms as predictive factors for functional outcome in A.D. METHODS: This was a retrospective study. Subjects were recruited from the Memory Clinic in Queen Mary Hospital over a two years period. Patients with diagnosis of probable A.D. by NINCDS-ADRDA were identified. Demographic data, Folstein Mini-Mental Status Examination (MMSE), Clinical Dementia Rating (CDR), Neuropsychiatric inventory (NPI), Barthel activities of daily living (ADL) as well as Lawton's Instrumental activities of daily living (IADL) were retrieved. RESULTS: 100 patients were identified. Univariate analysis identified statistically significant correlation between hallucination and disinhibition score with Barthel Index (r=-0.43, p <0.001; r=-0.30, p=0.002 respectively); hallucination and aberrant motor act score with Lawton's IADL (r=-0.21, p=0.038; r=-0.21, p=0.038). MMSE was statistical significantly correlated with the above two functional scores. NPI was not statistical significantly correlated with any one of the functional measures. Multivariate regression analyses showed that hallucination score was an independent predictive factors for the Barthel index but not for the Lawton's IADL. MMSE score was identified to be independent predictive factor for all functional measures. CONCLUSIONS: Global cognitive impairment and hallucination was an important independent predictive factor for functional outcomes. Screening hallucination during the course of A.D. would be helpful. Further studies are needed to show the benefit of treatment of hallucination on the improvement of functional outcomes.

Activities of Daily Living↗

PubMed2001

Molded porous poly (L-lactide) membranes for guided bone regeneration with enhanced effects by controlled growth factor release.

The aim of this study was to develop platelet-derived growth factor (PDGF-BB) loaded moldable porous poly (L-lactide) (PLLA)-tricalcium phosphate (TCP) membranes for guided bone regeneration (GBR) therapy. The membranes were designed to fit various types of bone defect sites. PDGF-BB-dissolved PLLA-TCP in methylene chloride-ethyl acetate solution was cast on a dome shaped metallic mold to fabricate a model membrane. The release rate of PDGF-BB, the osteoblast attachment test, and guided bone regeneration potential were evaluated with PDGF-BB-loaded PLLA-TCP membranes. Regular pores were generated throughout the membrane mainly due to phase inversion of PLLA-methylene chloride-ethyl acetate solution. A therapeutic amount of PDGF-BB was released from the membrane. The release rate could be controlled by varying the initial loading content of PDGF-BB. A significant amount of cells attached onto the PDGF-BB-loaded membrane rather than onto the unloaded membrane. Dome shaped bone formation was achieved in rabbit calvaria at 4 weeks. This indicated that restoration of bone defects to the bone's original shape can be made possible by using molded membranes, which guide bone regeneration along with providing sufficient spaces. Bone forming efficiency was increased remarkably due to PDGF-BB release from PLLA-TCP membranes. These results suggested that the PDGF-BB releasing molded PLLA-TCP membrane may potentially improve GBR efficiency in various types of bone defects.

Animals↗

PubMed2001

Tissue-engineered growth of bone by marrow cell transplantation using porous calcium metaphosphate matrices.

In this study we investigated not only osteoblastic cell proliferation and differentiation on the surface of calcium metaphosphate (CMP) matrices in vitro but also bone formation by ectopic implantation of these cell-matrix constructs in athymic mice in vivo. Interconnected porous CMP matrices with pores 200 microm in size were prepared to use as scaffolds for rat-marrow stromal-cell attachment. Cell-matrix constructs were cultured in vitro, and cell proliferation and ALPase activities were monitored for 56 days. In addition to their being cultured in vitro, cell-matrix constructs were implanted into subcutaneous sites of athymic mice. In vitro these porous CMP matrices supported the proliferation of osteoblastic cells as well as their differentiation, as indicated by high ALPase activity. In vivo the transplanted marrow cells gave rise to bone tissues in the pores of the CMP matrices. A small amount of woven bone formation was detected first at 4 weeks; osteogenesis progressed vigorously with time, and thick lamellar bones that had been remodeled were observed at 12 weeks. These findings demonstrate the potential for using a porous CMP matrix as a biodegradable scaffold ex vivo along with attached marrow-derived mesenchymal cells for transplantation into a site for bone regeneration in vivo.

Alkaline Phosphatase↗

PubMed2001

Cataract formation after pars plana vitrectomy.

To investigate the duration and pattern of cataract formation after pars plana vitrectomy, thirty-three eyes from 33 patients with complete data from March 1995 to January 2000 were collected in this study. The time and pattern of cataract formation was analyzed according to Lens Opacities Classification System III (LOCS III). The correlation between the mean cataract progression and follow-up time was determined by simple regression and correlation analysis. Diabetes mellitus and hypertension were the main causes of patients with vitreoretinopathy who underwent pars plana vitrectomy procedure. Twenty-one patients (63.6%) had diabetes mellitus and 11 patients (33.3%) had hypertension. Four eyes (13.8%) received intravitreal gas injection after pars plana vitrectomy. The correlation between cataract progression and follow-up time was clinically significant (p < 0.05). Thirty-one patients (94%) were nuclear cataract, the mean time of cataract formation being 9.1 months; 15 patients (46.9%) were cortical cataract, the mean time of formation being 8 months; and 24 patients (72.7%) were posterior subcapsular cataract, the mean time of formation being 13.3 months. Cataract formation after pars plana vitrectomy is not infrequent. Nuclear cataract is the most common type in this study. Vitreous microenvironmental changes, post-vitrectomy uveitis, intravitreal gas, and patient age may be the key points of cataract formation after surgery. The mechanism of longer-term effect of pars plana vitrectomy on lens status is still unknown and merits further study.

Adult↗

PubMed2000

Enhanced guided bone regeneration by controlled tetracycline release from poly(L-lactide) barrier membranes.

With the aim of providing effective periodontal therapeutic modality, drug-releasing membranes for guided tissue regeneration (GTR) were developed. As GTR membranes, biodegradable barrier membranes composed of porous poly(L-lactide) (PLLA) films cast on poly(glycolide) (PGA) meshes were fabricated using an in-air drying phase inversion technique. PLLA was dissolved in methylene chloride-ethylacetate mixtures, cast on knitted PGA mesh, and then air-dried. Tetracycline, which is used in periodontal therapy because of its antibacterial activity and tissue regenerating effects, including osteoblast chemotactic effect and anti-collagenolytic activity, was incorporated into the membranes by adding it to PLLA solutions. The guided bone regenerating potential of tetracycline-loaded membranes was evaluated using release kinetics both in vitro and in vivo, biodegradation tests, and cell attachment tests. Homogeneous pores were generated both at the surface and in a sublayer of the membranes. The release kinetics of tetracycline depended mainly upon the hydrophilicity of tetracycline and the porosity of the membrane. The release rate further could be controlled by loaded drug contents. The release of tetracycline was appropriate for maintaining anti-microbial activity and for its tissue-regenerating potential. The membranes retained a proper degradation property, maintaining their mechanical integrity for the barrier function for 4 weeks. Tetracycline-loaded membranes induced increased cell attachment levels compared with those of unloaded membranes. Tetracycline-loaded membranes markedly increased new bone formation in rat calvarial defects and induced bony reunion after 2 weeks of implantation. These results suggest that tetracycline-loaded PLLA membranes potentially enhance guided tissue regenerative efficacy.

Animals↗

PubMed2000

Controlled release of platelet-derived growth factor-BB from chondroitin sulfate-chitosan sponge for guided bone regeneration.

Platelet-derived growth factor-BB (PDGF-BB) releasing porous chondroitin-4-sulfate (CS)-chitosan sponge was designed with an aim of controlling growth factor delivery in order to improve bone formation. Porous CS-chitosan sponge was fabricated by freeze drying and crosslinking aqueous CS-chitosan solution. PDGF-BB was incorporated into the CS-chitosan sponge by soaking CS-chitosan sponge into the PDGF-BB solution. CS-chitosan sponge retained a porous structure with a 150-200-microm pore diameter that was suitable for cellular migration and osteoid ingrowth. Release rate of PDGF-BB could be controlled by varying the composition of CS in the sponge or initial loading content of PDGF-BB. CS-chitosan sponge induced increased osteoblast migration and proliferation as compared with chitosan sponge alone. Furthermore, the release of PDGF-BB from CS-chitosan sponge significantly enhanced osteoblast proliferation. These results suggest that PDGF-BB-releasing CS-chitosan sponge may be beneficial to enhance bone cell adaptation and regenerative potential when applied in wound sites.

Animals↗

PubMed2000

Platelet derived growth factor releasing chitosan sponge for periodontal bone regeneration.

With an aim of improving bone regeneration, chitosan sponge containing platelet-derived growth factor-BB (PDGF-BB) were developed. For fabrication of chitosan sponge, chitosan solution was freeze-dried, crosslinked and freeze-dried again. PDGF-BB was incorporated into the chitosan sponge by soaking chitosan sponge into the PDGF-BB solution. Release kinetics of PDGF-BB, cell attachment, proliferation capacity and bony regenerative potentials of PDGF-BB-loaded chitosan sponge were investigated. Prepared chitosan sponge retained porous structure with 100 microm pore diameter that was suitable for cellular migration and growth. Release rate of PDGF-BB could be controlled by varying initial loading content of PDGF-BB to obtain optimal therapeutic efficacy. PDGF-BB-loaded chitosan sponge induced significantly high cell attachment and proliferation level, which indicated good cellular adaptability. PDGF-BB-loaded chitosan sponge demonstrated marked increase in new bone formation and rapid calcification. Degradation of the chitosan sponge was proceeded at defect site and subsequently replaced with new bone. Histomorphometric analysis confirmed that PDGF-BB-loaded chitosan sponge significantly induced new bone formation. These results suggested that chitosan sponge and PDGF-BB-loaded chitosan sponge may be beneficial to enhance periodontal bone regeneration.

Animals↗

PubMed2000

A randomized clinical trial comparing autologous blood clot and gelfoam in transarterial chemoembolization for inoperable hepatocellular carcinoma.

BACKGROUND/AIM: Inoperable hepatocellular carcinoma is common in Asia and is usually treated with repeated transarterial chemoembolization. Gunji et al. showed better survival and fewer complications with autologous blood clot as compared with gelfoam used for embolization. Our aim was to compare the effect of blood clot versus gelfoam. METHODS: We conducted a prospective randomized trial in 100 patients with inoperable hepatocellular carcinoma, and compared the side effects and cumulative survival in the two groups. Cox's proportional hazard model was used to study the prognostic factors. RESULTS: The diameter of the main tumor was 7.9+/-4.6 cm. Our study did not show additional beneficial effects of blood clot. The proportion of side effects was similar and the common ones included fever, pain and vomiting. Though the hepatic artery remained patent for a longer period with blood clot (p=0.061), there was no difference in survival (p=0.129 for Okuda I disease and p=0.388 for Okuda II disease). Subgroup analysis showed longer survival in patients with vascular occlusion (p=0.034 for Okuda I and p=0.029 for Okuda II disease). The independent factors of survival were sex, Child's class, Okuda stage, tumor type and presence of metastases. CONCLUSION: This study showed no additional benefits of blood clot in patients with inoperable hepatocellular carcinoma, in Okuda I and II disease. The longer survival in patients with vascular occlusion suggested that the damage to normal liver tissue by planned periodic transarterial chemoembolization may outweigh its benefit in later sessions of repeated TACE in certain patients.

Aged↗

PubMed2000

Tissue engineered bone formation using chitosan/tricalcium phosphate sponges.

BACKGROUND: Chitosan is a biodegradable natural polymer that has been shown to improve wound healing. This study aimed to develop chitosan/tricalcium phosphate (TCP) sponges as tissue engineering scaffolds for bone formation by three-dimensional osteoblast culture. METHODS: The sponges were prepared by freeze-drying and cross-linking a mixture of chitosan solution with TCP. Fetal rat calvarial osteoblastic cells were isolated, cultured, and seeded into the sponges. The cell-sponge constructs were cultured for 56 days. Cell proliferation, alkaline phosphatase (ALPase) activity, and calcium deposition in the cell-sponge constructs were measured at 1, 7, 14, 28, and 56 days. Histologic examination was performed with light microscopy and scanning electron microscopy. RESULTS: Chitosan/TCP sponges supported the proliferation of osteoblastic cells as well as their differentiation as indicated by high ALPase activities and deposition of mineralized matrices by the cells. Light and scanning electron microscopic examination indicated that seeded osteoblastic cells were well attached to sponge matrices and proliferated in a multi-layer fashion. Small bone-like spicules were observed on the sponge matrix at 14 days. Seeded cells appeared to be embedded in the newly formed tissue matrix, which is characteristic of the osteoblast differentiation and their progression into osteocytic cells. The amount of mineralized tissue formed in the sponge at 56 days was significant. CONCLUSIONS: These results suggest that the chitosan/TCP sponge is a feasible tool as a scaffolding material to grow osteoblast in a three-dimensional structure for transplantation into a site for bone regeneration.

Absorbable Implants↗

PubMed2000

The bone regenerative effect of platelet-derived growth factor-BB delivered with a chitosan/tricalcium phosphate sponge carrier.

BACKGROUND: In order to achieve optimal effects, growth factors including platelet-derived growth factor (PDGF) should be delivered with a biodegradable carrier that will release therapeutic concentrations over a sufficient length of time. The purpose of this study was to evaluate the bone regenerative effect of PDGF-BB delivered with a chitosan/tricalcium phosphate (TCP) sponge carrier in a rat calvarial defect model. METHODS: The PDGF-BB-loaded chitosan/TCP sponge carrier was fabricated by freeze-drying a mixture of chitosan solution and TCP powder and soaking in a PDGF-BB solution. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with 125I-labeled PDGF-BB. Chitosan/TCP sponges with and without PDGF-BB were implanted into 8 mm calvarial defects in rats. Rats were sacrificed at 2 and 4 weeks following implantation, and histologic and histomorphometrical examinations were performed. RESULTS: In vitro evaluation demonstrated that an effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. In the histologic examination, the chitosan/TCP sponge carrier promoted osseous healing of the rat calvarial defects as compared to controls. The addition of PDGF-BB to the carrier further enhanced bone regeneration. Evidence of the degraded sponge matrix was observed mingled within the newly formed bone without connective tissue encapsulation. CONCLUSIONS: The results of this study support the use of chitosan/TCP sponges as a delivery system for growth factors and demonstrate that PDGF-BB loaded onto chitosan/TCP sponge carriers has an osteogenic effect on bone regeneration in vivo.

Absorbable Implants↗

PubMed1999

Staphylococcus lugdunensis--a potential pathogen in oral infection.

OBJECTIVE: The purpose of this study was to investigate the pathogenicity of Staphylococcus lugdunensis in acute oral infection. STUDY DESIGN: S. lugdunensis was isolated from patients with acute oral infections and from healthy control subjects. Antibiotic susceptibility, in vitro cellular toxicity, in vivo virulence, and hemolytic activity testing and dot blot analysis were performed. The statistical significance of in vitro cellular toxicity was determined by means of analysis of variance. RESULTS: Isolated from the infected patients, S. lugdunensis showed resistance to penicillin, ampicillin, methicillin, cephalothin, and clindamycin, exhibited virulence in vivo, and showed delta-like hemolysin activity. Four of the 6 strains of S. lugdunensis gave synergistic hemolysis. In dot blot analysis, S. lugdunensis showed a positive reaction to the probe of the delta-hemolysin gene in S. aureus. CONCLUSIONS: The results suggest that S. lugdunensis may be a potential pathogen in acute oral infection.

Abscess↗

PubMed1998

Controlled release of platelet-derived growth factor from porous poly(L-lactide) membranes for guided tissue regeneration.

Platelet-derived growth factor-BB (PDGF-BB) was incorporated into porous poly (L-lactide) (PLLA) membranes with an aim of improving early bone healing in guided tissue regeneration (GTR) therapy. Porous PDGF-BB loaded membranes were fabricated by coating PDGF-BB-dissolved PLLA methylene chloride-ethyl acetate solutions on polyglycolic acid (PGA) meshes. Release kinetics of PDGF-BB, biologic activity, degradability and guided tissue regenerative potentials of the membranes were investigated. Release of PDGF-BB could be controlled by adding bovine serum albumin that may provide porous diffusion channels for PDGF-BB release and by varying initial loading content of PDGF-BB. Biologic activity of PDGF-BB in the membranes was ascertained by fibroblast chemotaxis. PDGF-BB loaded membranes maintained proper degradation property for periodontal application. PDGF-BB loaded membrane markedly increased new bone formation in rat calvarial defects, and completed bony reunion after 2 weeks of implantation period. These results suggested that PDGF-BB loaded PLLA membrane might potentially enhance guided tissue regenerative efficacy.

Acetates↗

PubMed1997

Biological effects of drug-loaded biodegradable membranes for guided bone regeneration.

The biological effects of drug-loaded biodegradable novel membrane for guided bone regeneration (GBR) was evaluated. The membranes were polyglycolic acid mesh coated with poly-L-lactic acid containing flurbiprofen, tetracycline or PDGF-BB. Porous structure was generated in the membranes by using a phase inversion method. The membrane was less toxic, nicely biodegradable and biocompatible for 8 wk after implantation in the dorsal skin of the rat. The drugs released from the membranes were shown to be effective for new bone formation. Tetracycline, flurbiprofen or PDGF-BB loaded membrane was markedly effective for osteoid tissue and new bone formation in the bony defect prepared in rat calvaria to compare with that by unloaded membrane. These results suggested that drug-loaded biodegradable barrier membrane might be a potential tool for GBR in periodontal therapy.

Analysis of Variance↗

PubMed1997

Racial tropism of a highly toxic clone of Actinobacillus actinomycetemcomitans associated with juvenile periodontitis.

Actinobacillus actinomycetemcomitans strains with enhanced levels of production of leukotoxin are characterized by a 530-bp deletion from the promoter region of the leukotoxin gene operon. Previous isolates with this deletion constituted a single clone belonging to serotype b, although they displayed minor differences among each other. We have analyzed the geographic dissemination of this clone by examining 326 A. actinomycetemcomitans isolates from healthy and periodontally diseased individuals as well as from patients with different types of extraoral infections originating from countries worldwide. A total of 38 isolates, all belonging to the same clone, showed the 530-bp deletion. Comparison of a 440-bp sequence from the promoter region of the leukotoxin gene operon from 10 of these strains revealed complete identity, which indicates that the deletion originates from a single mutational event. This particular clone was exclusively associated with localized juvenile periodontitis (LJP). In at least 12 of 28 families from which the clone was isolated, more than one family member had LJP. Notably, all the subjects carrying this clone had a genetic affiliation with the African population. These observations suggest that juvenile periodontitis in some adolescents with an African origin is associated with a disseminating clone of A. actinomycetemcomitans.

Actinobacillus Infections↗