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Biomedical subjects

K D Thompson

Publications and source records attributed to K D Thompson.

At least 37 records · Page 2Linked to original sources
PubMed1993

Characterization of human keratinocytes transformed by high risk human papillomavirus types 16 or 18 and herpes simplex virus type 2.

Recent reports implicate two DNA tumour viruses, herpes simplex virus type 2 (HSV-2) and human papillomavirus types 16 or 18 (HPV-16 and -18), in the pathogenesis of cervical cancer. Previous studies have indicated that primary human fibroblasts transfected with HPV-16 and HSV-2 morphological transforming region III (mtr III) are more aneuploid than fibroblasts immortalized with HPV-16 and that HSV-2 DNA sequences are retained in transformed cells. Since HSV-2 and HPV typically infect cells of epithelial origin, the interactions of these viruses with respect to morphological transformation were examined in human keratinocytes. HPV-16- or HPV-18-immortalized keratinocytes (FEPL and FEA cells, respectively) were transfected with fragments derived from HSV-2 mtr III. When compared to their normal counterparts, FEPL cells and FEA cells transfected with mtr III fragments grew to higher saturation densities and were morphologically transformed. FEPL cells transformed by HSV-2 were capable of growth in soft agar and, when injected into nu/nu mice, lesions developed at the site of injection. Histological examination of the lesions revealed a benign mass which was composed of squamous epithelial cells that were producing keratin. In contrast, immortalized keratinocytes (FEPL or FEA) or FEA cells transfected with HSV-2 did not produce these lesions. These observations suggest that sequences within mtr III can alter the growth properties of human keratinocytes immortalized by HPV-16 or HPV-18.

Animals↗
PubMed1993

Antibacterial activity of lidocaine in combination with a bicarbonate buffer.

BACKGROUND: The antibacterial properties of lidocaine have been previously described. Recent reports indicated that the addition of NaHCO3 to lidocaine reduces the pain associated with the injection. This study was conducted to determine the antibacterial activity of lidocaine buffered with NaHCO3. METHODS: Rates of killing of six species of bacteria were determined in the presence of buffered and unbuffered lidocaine. When bacteria were incubated with lidocaine buffered with NaHCO3 at either 25, 50, or 100 mEq/L, there was a decrease of > 99% of all bacteria tested over the 6 hours of the assay. This dramatic rate of killing was not observed in the unbuffered control preparations. RESULTS: The results of this study indicate that NaHCO3 enhances the killing effect that has been described for lidocaine alone. The inability to recover common pathogenic bacteria from biopsy specimens could be the result of exposure to local anesthetic agents such as lidocaine that are buffered with NaHCO3.

Anti-Bacterial Agents↗
PubMed1993

Skeletal muscle Ca2+ flux and catabolic response during sepsis.

Membrane Ca2+ flux and net protein catabolism were studied in the skeletal muscle during experimental sepsis. Sterilized rat fecal pellets with (septic) or without (sterile) gram-negative bacteria, Escherichia coli [10(2) colony-forming units (cfu)] and Bacteroides fragilis (2 x 10(3) cfu), were implanted into the abdomens of male Sprague-Dawley rats (110-120 g). Septic and sterile rats were febrile and hyperlactacidemic on day 1 postimplantation. These responses subsided by day 2 in sterile but not septic rats. Initial Ca2+ flux, estimated from measurements of 45Ca uptake by soleus muscles in vitro, was elevated on day 1 in both sterile and septic rats and on day 2 and 3 in septic rats only. The septic rat soleus muscle showed a significantly increased net protein catabolic response (measured as tyrosine release by soleus muscle, in vitro) over that found in muscles of sterile rats on day 1-3 postimplantation. The increase in Ca2+ flux in septic (day 1-3 postimplantation) and sterile (day 1 only) rats was abolished when the rats were treated with the calcium channel blocker diltiazem. In unoperated control rat soleus muscles the Ca2+ ionophore, ionomycin, concomitantly caused an increase in Ca2+ flux and net protein catabolism. Overall, the present study suggested that altered cellular Ca2+ regulation plays a role in the net protein catabolic response in the skeletal muscle during sepsis.

Animals↗
PubMed1992

Oxidative tryptophan metabolism in renal allograft recipients: increased kynurenine synthesis is associated with inflammation and OKT3 therapy.

Serum concentrations of tryptophan (TRP) and kynurenine (KYN) were determined in renal allograft recipients (RAR) as an index of interferon-gamma-induced, indoleamine-dioxygenase-catalysed TRP degradation. Serum TRP and KYN in RAR during periods of stable graft function were typically within the normal range, however, the median values for serum KYN demonstrated significant increases 5-7 days prior to biopsy-confirmed acute rejection (1.6-fold, P less than 0.01) and on the day of biopsy (1.7-fold, P less than 0.001). Serum KYN was also markedly elevated in patients who contracted viral or Gram-negative bacterial infections in the absence of graft rejection. Serum KYN was not correlated with serum creatinine in RAR nor were serum TRP or KYN affected by antirejection therapy with high dose steroids. Retrospective analysis of intra-patient changes in serum KYN demonstrated that KYN monitoring was a useful adjunct to serum creatinine in the early detection of first acute rejection episodes. The first course of OKT3 therapy was associated with low serum TRP and significant increases in serum KYN (two- to three-fold) following the first three doses. The time course of these abnormalities corresponded to that over which many of the side effects of the OKT3 'first dose reaction' have been reported to occur. Significant changes in serum KYN were not observed in patients receiving repeat courses of OKT3 therapy. Significant decreases in serum TRP and significant increases in serum KYN were both prevalent and frequent in RAR during the first two postoperative months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

A ganciclovir-resistant clinical isolate of human cytomegalovirus exhibiting cross-resistance to other DNA polymerase inhibitors.

Clinical isolates of human cytomegalovirus (HCMV) were screened for susceptibility to ganciclovir by plaque-reduction assay and in situ ELISA. A pretreatment isolate of HCMV obtained from the bronchial brushing of a heart transplant recipient contained both ganciclovir-susceptible and -resistant virus. Ganciclovir-susceptible (P8) and -resistant (D16) strains were further isolated by plaque purification. Both strains phosphorylated ganciclovir at levels similar to the ganciclovir-susceptible strain AD169. D16 was also resistant to phosphonoformic acid and to (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)adenine and cytosine. These data suggest that the resistance of D16 to these drugs results from a mutation in the viral DNA polymerase gene.

Antiviral Agents↗
PubMed1992

Characterization of primary human fibroblasts transformed by human papilloma virus type 16 and herpes simplex virus type 2 DNA sequences.

Human papilloma virus type 16 (HPV-16) and herpes simplex virus type 2 (HSV-2) are human viruses implicated in the development of cancer, in particular cervical cancer. The ability of HSV-2 and HPV-16 to transform early passage human cells was examined in this report. For these studies, gingival fibroblasts were utilized. One gingival cell strain was derived from a normal individual (N-16). The second cell strain was derived from hyperplastic gingival tissue of an epileptic individual (R-30) treated with phenytoin, an antiseizure drug. A common side effect of phenytoin is the induction of gingival overgrowth. R-30 cells contained a stable chromosomal translocation between chromosomes 8 and 18 and expressed higher steady state levels of c-myc. HPV-16 DNA efficiently immortalized R-30 cells but not N-16 cells. R-30 cells cotransfected with HPV-16, and HSV-2 viral DNAs were more aneuploid than R-30 cells transfected with HPV-16 DNA alone. Additionally, R-30 cells cotransfected with both viral DNAs grew better in soft agar than R-30 cells transfected with HPV-16 DNA alone. HSV-2 DNA was detected in transformed cells by polymerase chain reaction. These results suggested R-30 cells were immortalized more efficiently by HPV-16 and further imply that HPV-16 and HSV-2 DNA fragments can cooperate during multistep transformation.

Base Sequence↗
PubMed1992

Use of a primary isolation medium for recovery of methicillin-resistant Staphylococcus aureus.

Clinical specimens frequently contain methicillin-resistant Staphylococcus aureus (MRSA) isolates in low numbers or mixed with methicillin-susceptible staphylococci, which can obscure MRSA on nonselective media. By using an oxacillin-containing mannitol-salt-based selective and differential medium on 936 respiratory specimens, we recovered 45% more MRSA isolates (29 versus 20) than on nonselective media alone.

Bacteriological Techniques↗
PubMed1992

Point mutations in the DNA polymerase gene of human cytomegalovirus that result in resistance to antiviral agents.

Three independently isolated mutants of human cytomegalovirus strain AD169 were found to be resistant to ganciclovir at a 50% effective dose of 200 microM. Phosphorylation of ganciclovir was reduced 10-fold in mutant-infected cells compared with AD169-infected cells. All three mutants were also determined to be resistant to the nucleotide analogs (S)-1-[(3-hydroxy-2- phosphonylmethoxy)propyl]adenine (HPMPA) and (S)-1-[(3-hydroxy-2-phosphonylmethoxy)propyl]cytosine (HPMPC) and hypersensitive to thymine-1-D-arabinofuranoside (AraT). Single base changes resulting in amino acid substitutions were demonstrated in the nucleotide sequence of the DNA polymerase gene of each mutant. The polymerase mutation contained in one of the mutants was transferred to the wild-type AD169 background. Ganciclovir phosphorylation in cells infected with the recombinant virus produced by this transfer was found to be equivalent to that of AD169-infected cells. The ganciclovir resistance of the recombinant was reduced fourfold compared with that of the parental mutant; however, the recombinant remained resistant to HPMPA and HPMPC and hypersensitive to AraT. The ganciclovir resistance of the mutants therefore appears to result from mutations in two genes: (i) a kinase which phosphorylates ganciclovir and (ii) the viral DNA polymerase.

Amino Acid Sequence↗
PubMed1992

Ca(2+)-related hepatocellular alterations during intra-abdominal sepsis.

Intra-abdominal sepsis was induced in rats by implanting into their abdominal cavities fecal-agar pellets impregnated with Escherichia coli and Bacteroides fragilis. Sham-operated rats received sterile pellets. A group of sterile- and septic-implanted rats was treated intraperitoneally with diltiazem (1.2 mg/kg) 8 h after implantations. Septic- and sterile-implanted rat hepatocytes were loaded with 1) the fluorescent dye indo-1 to quantify hepatocyte basal and vasopressin (100 nM)-elevated cytosolic Ca2+ concentration and 2) 45Ca to quantify Ca2+ flux and cellular content of exchangeable Ca2+. Lipid peroxidation was determined by measuring conjugated dienes (CD) and thiobarbiturate-reactive substances (TBA-RS) in liver homogenates. In septic-implanted rats, the basal cytosolic [Ca2+], cellular exchangeable Ca2+, Ca2+ flux, CD, and TBA-RS were significantly higher than in sterile-implanted rats. Although vasopressin caused a significant elevation in cytosolic [Ca2+] in septic rat hepatocytes, the magnitude of this elevation was significantly smaller than that found in the sterile group. Diltiazem treatment of septic rats significantly decreased basal cytosolic [Ca2+], cellular exchangeable Ca2+ content, Ca2+ flux, CD, and TBA-RS. Also, vasopressin-induced increase in hepatocyte cytosolic [Ca2+] in diltiazem-treated septic rats was significantly greater than that observed in untreated septic rats. Both Ca2+ and membrane lipid alterations were attenuated with diltiazem treatment of septic rats. These results suggest that prevention or attenuation of Ca2+ channel-mediated Ca2+ influx restores both Ca2+ homeostasis and membrane lipid alteration.

Abdomen↗
PubMed1991

Anterior chamber aspirate cultures after uncomplicated cataract surgery.

We cultured anterior chamber aspirates of 30 patients who had uncomplicated extracapsular cataract extraction or phacoemulsification. The aspirate was obtained at the time of wound closure. Of 30 patients, 13 (43%) had culture-positive anterior chamber aspirates. The total number of organisms recovered was 18, with three patients having multiple organisms identified. The most commonly isolated organisms were coagulase-negative Staphylococcus sp., occurring in eight of 18 isolates (44%). No eyes in our study developed endophthalmitis, even though almost one half had viable organisms growing from the anterior chamber aspirates. Inoculum sizes were extremely small (10 to 20 colony-forming units/ml). This study suggests that in humans, the anterior chamber is capable of clearing a low inoculum of bacteria after cataract surgery without the development of endophthalmitis.

Anterior Chamber↗
PubMed1991

Evaluation of three commercial enzyme immunoassays for toxoplasma and cytomegalovirus antibodies.

Three commercially available enzyme immunoassays (EIAs) were evaluated for specificity and sensitivity compared to immunofluorescent assays (IFAs) for detection of IgG and IgM antibodies to Toxoplasma gondii (Toxo) and Cytomegalovirus (CMV). A panel of 78 sera were tested, including specimens known to contain Toxo IgG or IgM, CMV IgM or IgM, antinuclear antibodies (ANA), antimitochondrial antibodies (AMA), and rheumatoid factor (RF). Linear correlation analysis comparing EIA and IFA results showed that the statistical relationship between the two assay methods was relatively weak (correlation coefficients ranging from 0.33 to 0.86). Qualitative correlation showed that the EIA methods agreed with IFA results in most cases. One manufacturer's products (Diamedix Corp.) gave consistently better sensitivity, specificity, and intra-assay reproducibility values than the other two systems (Clinical Sciences, Inc., and Whittaker Bioproducts). ANA, AMA, and RF did not appear to interfere with any EIAs.

Animals↗
PubMed1986

Rapid detection of cytomegalovirus in clinical specimens by using biotinylated DNA probes and analysis of cross-reactivity with herpes simplex virus.

A method for rapid identification of human cytomegalovirus (HCMV) was developed with biotinylated DNA probes. BamHI restriction fragments from HCMV strain AD169 were selected and tested for their ability to detect virus in patient urine samples. All probes detected 30 pg of HCMV AD169 DNA. The BamHI B fragment detected 15 of 29 cell-culture-positive samples (sensitivity, 52%). There were four samples which were probe positive and cell culture negative (specificity, 87%). The D and H fragments used as combined probes detected 17 of 21 cell-culture-positive samples (sensitivity, 81%). There were five probe-positive and cell-culture-negative samples (specificity, 68.8%). The H fragment, when used alone, detected 11 of 14 culture-positive samples, and 5 samples were culture negative and probe positive. Sensitivity (78.6%) and specificity (76.2%) for the H fragment were similar to those for the combined probes, but the color intensity of the positive reactions detected by the H fragment alone was lower. There was unexpected cross-reactivity with herpes simplex type 1 and 2 controls when the combined D and H probes were used. Specific hybridization was demonstrated between subfragments of the HCMV BamHI D fragment and the herpes simplex virus type 1 EcoRI M fragment.

Cytomegalovirus↗
PubMed1985

Detection of group A streptococcal antigen directly from throat swabs with a ten-minute latex agglutination test.

Results obtained with the Culturette brand 10-Minute Group A Strep ID system were compared with culture results to measure the ability of this system to detect group A streptococci directly from more than 800 throat swabs. Our study showed a sensitivity of 92.4% and a specificity of 92.8% for this acid extraction, latex agglutination method when compared with anaerobic culturing for group A streptococci. The results suggest that the 10-Minute Group A Strep ID method may prove to be a useful, very rapid and easy method for diagnosing group A streptococcal pharyngitis directly from throat swabs. Further studies are suggested to determine whether this diagnostic method could stand alone or would have to be used in conjunction with culture.

Agglutination↗
PubMed1982

Activity of metronidazole and its hydroxy and acid metabolites against clinical isolates of anaerobic bacteria.

Susceptibility of clinical isolates of anaerobic bacteria to metronidazole and its two oxidation products, 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole (the "alcohol" metabolite) and 2-methyl-5-nitroimidazole-1-acetic acid (the "acid" metabolite), were determined by the agar dilution technique. Results disclosed that the alcohol metabolite, although less active than metronidazole, inhibited the organisms tested at levels considered susceptible for metronidazole. The acid metabolite was less active, not inhibiting the organisms at levels within the susceptible range. In other studies, mixtures of known concentrations of metronidazole and the metabolites were assayed in a bioassay system used to measure metronidazole levels. These studies showed that the bioassay will measure metronidazole or the alcohol metabolite; the acid metabolite is not measured at levels achieved in clinical specimens. Since the activity of the alcohol metabolite is comparable to that of metronidazole, we feel that microbiological assays can be used for therapeutic monitoring of metronidazole levels in clinical situations.

Anaerobiosis↗
PubMed1981

Staphylococcal protein-A agglutination assay for avian viruses.

Protein-A rich staphylococci were used to develop an agglutination assay for the detection and quantitation of avian reticuloendotheliosis virus (REV) and Herpes virus of turkeys (HVT). Rabbit anti-REV or anti-HVT were used to coat the staphylococci and these reagents were mixed with REV or various other viral antigen preparations. An agglutination titer was determined for antigen preparations of varying purity and the results indicated that in addition to being rapid, this assay allows the detection of as little as 0.3 to 0.5 microgram of partially purified viral antigens. No crossreactivity was observed with the two antisera and the various antigen preparations. This study also confirmed the reports in the literature that chicken immunoglobulins do not bind to protein-A of the Cowan I strain of Staph. aureus.

Agglutination Tests↗
PubMed1980

Chronic herpes simplex infection in cutaneous T-cell lymphomas.

Therapeutically unresponsive erosive or ulcerative lesions caused by the herpes simplex virus developed in five patients with advanced cutaneous T-cell lymphoma. The chronic progressive character of the herpetic infection probably was the consequence of immunosuppression resulting from advanced lymphoma or its treatment. Herpes simplex infection should be considered in the differential diagnosis of cutaneous ulcerations in patients with cutaneous T-cell lymphomas.

Aged↗