Biomedical subjects

D R Nash

Publications and source records attributed to D R Nash.

At least 37 records · Page 2Linked to original sources

PubMed1988

Human disease due to Mycobacterium smegmatis.

Mycobacterium smegmatis is a rapidly growing environmental species not considered a human pathogen. We identified 22 human isolates of M. smegmatis from Australia and the southern United States: 19 were from skin or soft-tissue infections, and none were from urine or the male genital tract. These isolates closely resembled Mycobacterium fortuitum, except for a negative three-day arylsulfatase test; growth at 43-45 C; a low semiquantitative catalase test; and, in 50% of isolates, a late-developing, yellow-to-orange pigment. The isolates were biochemically identical to four reference strains and the type strain of M. smegmatis. Isolates were resistant to isoniazid and rifampin but susceptible to ethambutol, doxycycline, sulfamethoxazole, ciprofloxacin, imipenem, and amikacin. Eleven patients treated on the basis of in vitro susceptibility tests responded well to therapy. The similarity of M. smegmatis to M. fortuitum and the failure to recognize that the former is an environmental species may have contributed to previous failures to recognize it as a human pathogen.

Arylsulfatases↗

PubMed1987

Beta-lactam resistance in Nocardia brasiliensis is mediated by beta-lactamase and reversed in the presence of clavulanic acid.

Forty clinical isolates and the type strain of Nocardia brasiliensis were screened for susceptibility to 20 beta-lactams. Isolates exhibited a single pattern of resistance, with large zones of inhibition by disk diffusion and low MICs by broth and agar dilutions only to cefotaxime, ceftriaxone, ceftizoxime, Augmentin, and Timentin. All strains produced beta-lactamase, with five different enzyme patterns by isoelectric focusing. Despite the differences in their isoelectric points, the enzymes had the same substrate profiles, with equivalent activity against penicillin, ampicillin, cefamandole, cephalothin, and cephalordine. In an in vitro assay, the enzymes were highly susceptible to clavulanic acid. The MIC50 and MIC90 for the combination of amoxicillin and clavulanic acid (Augmentin) was 2 and 4 micrograms/ml, respectively, compared with 16 micrograms/ml for both values for amoxicillin alone. These studies suggest that beta-lactamase is the major mechanism of beta-lactam resistance in this species and that Augmentin is the first oral beta-lactam with good potential for treating infections due to N. brasiliensis.

Amoxicillin↗

PubMed1986

Disk diffusion susceptibility of Branhamella catarrhalis and relationship of beta-lactam zone size to beta-lactamase production.

We tested 231 isolates of Branhamella catarrhalis for beta-lactamase production and drug susceptibility by the National Committee for Clinical Laboratory Standards disk diffusion method. The nitrocephin disk (Cefinase) identified beta-lactamase in 98% of the enzyme-producing strains, and a zone diameter of inhibition of less than or equal to 29 mm for penicillin correctly predicted the presence of beta-lactamase in 99% of the isolates. No resistance to erythromycin, tetracycline, trimethoprim-sulfamethoxazole, or amoxicillin-clavulanic acid was observed.

Anti-Bacterial Agents↗

PubMed1986

Susceptibility testing of slowly growing mycobacteria by a microdilution MIC method with 7H9 broth.

Based on previous success with rapidly growing mycobacteria, a microdilution MIC system was devised for slowly growing mycobacterial species using 7H9 broth. Test drugs included isoniazid, rifampin, ethambutol, streptomycin, clofazamine, and sulfamethoxazole. Sixty isolates of four mycobacterial species, including Mycobacterium tuberculosis, from patients who had never received drug therapy were evaluated in the system, as well as 25 drug-resistant isolates and 11 control strains. MICs were read when good macroscopic control growth was evident, a period which varied with each species. Most species exhibited a narrow range of MICs with easily discernible growth endpoints. The aminoglycosides, ethambutol, clofazamine, and sulfamethoxazole were the only drugs with activity against all species at clinically achievable levels in serum. Correlation between susceptibilities by the proportion method in agar with single drug concentrations and the broth method were excellent for M. tuberculosis, M. kansasii, and M. marinum for isoniazid, rifampin, and ethambutol. Isolates of the M. avium complex were much more susceptible in broth than in agar for rifampin, ethambutol, and streptomycin. Given the successful transition of most microbiology laboratories to MIC plates for other bacterial species, this method would allow for testing of multiple drugs at multiple concentrations and has good potential for evaluation of drug combinations and drug-resistant isolates.

Anti-Bacterial Agents↗

PubMed1986

Characterization of beta-lactamases in Mycobacterium fortuitum including a role in beta-lactam resistance and evidence of partial inducibility.

The beta-lactamases from the 3 biovariants of M. fortuitum were compared on the basis of substrate profiles, susceptibility to enzyme inhibitors, and inducibility in the presence of selected beta-lactams. Despite differences in the distribution of beta-lactamase bands observed when enzymes from different isolates were subjected to isoelectric focusing, substrate profiles for the 3 biovariants were similar. All demonstrated a comparable broad spectrum hydrolytic activity for both cephalosporins and penicillins. The MIC for amoxicillin were reduced 4- to 16-fold when combined with the beta-lactamase inhibitor clavulanic acid, but not to a clinically susceptible range. The degree of reduction in MIC for amoxicillin correlated well with the susceptibility of enzyme to inhibition by clavulanic acid as determined in an in vitro assay. Although all M. fortuitum strains produce beta-lactamase under routine growth conditions, 90% of strains demonstrated an increase in the amount of this enzyme when cultured in the presence of selected beta-lactams as potential inducers. Quantitative assays and isoelectric focusing further indicated that this apparent induction of beta-lactamase is a simple enhancement of the same enzyme(s) produced in the absence of a known inducer. This is the first demonstration of any inducibility among mycobacterial beta-lactamases and suggests that synthesis of these enzymes in M. fortuitum is under some form of regulatory control. These results indicate that the beta-lactamases have a role in resistance of M. fortuitum to the beta-lactams. Other factors, such as permeability and penicillin-binding proteins, were not evaluated.

Drug Resistance, Microbial↗

PubMed1986

Isoelectric focusing of beta-lactamases from sputum and middle ear isolates of Branhamella catarrhalis recovered in the United States.

Branhamella catarrhalis obtained from the sputum of 146 patients with lower respiratory tract disease and from middle ear fluids of 26 children with otitis media were evaluated for beta-lactamase activity and the enzymes were characterised by isoelectric focusing (IEF). 71% (103 of 146) of the sputum isolates and 77% (20 of 26) of the ear isolates produced beta-lactamase. By IEF, the beta-lactamases of 113 of 123 (92%) strains revealed patterns identical with the Ravasio type strain, having unique enzyme bands at pIs of 6.4 and 6.65. The remaining 10 isolates (8%) produced patterns similar to the 1908 type strain with a unique band of activity having a pI of 6.55. In addition, the 1908 types revealed a band of minor enzyme activity with a pI of 7.55 that was absent from the Ravasio types. All strains tested shared major enzyme bands with pIs of 5.1, 5.3, 5.55 and 6.1. These results indicate that the most common beta-lactamase(s) produced by clinical isolates of B. catarrhalis in the United States are similar to those produced by the Belgian Ravasio type strain.

Humans↗

PubMed1986

Incidence of Branhamella catarrhalis in the sputa of patients with chronic lung disease.

The incidence of Branhamella catarrhalis in the respiratory tract of adults, especially in the United States, is not known. During the 30-month period from January 1983 to June 1985, 4180 sputum and endotracheal samples from patients in a hospital for chest diseases were evaluated. All samples were acceptable for Gram-stain analysis and/or culture based on published cellular criteria. Using primarily Gram-stain directed cultures, 220 isolates of B. catarrhalis were identified in 180 patients, being present in 5.3% of all sputum cultures and 11.5% of those positive for a pathogen. B. catarrhalis was the fourth most common pathogen identified. It was found in pure culture (124) and mixed culture (96), the latter usually in association with Haemophilus influenzae or Streptococcus pneumoniae. Of the 220 B. catarrhalis isolates, 158 (71.8%) were positive for beta-lactamase. The number and incidence of B. catarrhalis varied, with the organism being most prevalent during the winter months. Despite its frequent presence in sputum, B. catarrhalis was not recovered from pleural fluid or blood during the same period. This study demonstrates the frequent presence of B. catarrhalis in the sputum of adults with chronic lung disease, although the role of this organism as a pathogen was not determined.

Chronic Disease↗

PubMed1985

NMB: a human neuroblastoma cell line with specific opiate binding sites.

The human neuroblastoma cell line designated NMB (Brodeur et al., 1977, Cancer 40: 2256) has been shown to have specific opiate binding sites. These sites are highly stereospecific. Two characteristic delta specific peptides, D-Ala2-D-Leu5 enkephalin and D-Thr2-D-Thr6 enkephalin, have high affinity for the binding sites. Morphine binds specifically but with a much lower affinity. Dextrorphan and the mu specific peptide morphiceptin (Tyr-Pro-Phe-Pro-CO-NH2) do not bind to the site. The binding sites are heat and trypsin sensitive. Sodium ions specifically lower agonist binding to the sites. Approximately 14,000 binding sites per cell are found. The binding characteristics of these sites are very similar to those of the delta sites characterized on mouse neuroblastoma cell lines.

Binding Sites↗

PubMed1985

Isoelectric focusing of beta-lactamases in Mycobacterium fortuitum. Association of a single enzyme pattern with cefoxitin resistance.

The uninduced culture supernatants and cell extracts from 58 strains of the 3 biovariants (biovar) of Mycobacterium fortuitum were all positive for beta-lactamase with the chromogenic cephalosporin substrate. By analytical isoelectric focusing (IEF), 29 of 30 strains of biovar fortuitum exhibited an identical beta-lactamase pattern with 1 major band. In contrast, the beta-lactamases of biovar peregrinum and the unnamed third biovar were heterogeneous, with multiple bands and a variety of patterns. The pH range of isoelectric points for the beta-lactamases was relatively narrow, however, with most bands appearing between pH 4.3 and 5.2. Although additional genetic studies are required, these enzymes appear to be chromosomal, as they are present in all strains including some without detectable plasmids. Repeat isolates from the same patient obtained up to six months apart always had the same beta-lactamase pattern by IEF. Of the third biovar complex, 30% are cefoxitin resistant with minimal inhibitory concentrations greater than 32 micrograms/ml. All 9 cefoxitin-resistant isolates tested had the same unique beta-lactamase pattern by IEF, although this enzyme failed to hydrolyze cefoxitin while hydrolyzing cephalothin and benzylpenicillin. Thus, despite the association of cefoxitin-resistance with a single enzyme pattern, the role of this beta-lactamase in resistance is not known.

Cefoxitin↗

PubMed1985

Immunoglobulin E and other immunoglobulins in patients with eosinophilic pleural effusions.

Paired serum and pleural fluids from seven patients with eosinophilic pleural effusions (EPE) and seven control patients with noneosinophilic exudative pleural effusions (non-EPE) were quantitatively assayed for IgG, IgA, IgM, and IgE. A comparison of the absolute serum values, pleural fluid values, and pleural fluid/serum concentration ratios obtained for each immunoglobulin, including IgE, failed to detect any significant differences in the two groups. It is concluded that IgE in exudative effusions reflects passive filtration and diffusion from serum and that immunoglobulin concentrations have no apparent value when assessing EPE.

Adult↗

PubMed1983

Primary immune responsiveness and other observations in mice given oral dimethyl sulfoxide.

Mice were allowed to drink 5% DMSO in their drinking water ad libitum for a period of six weeks, during which time a number of variables were compared with age-, weight-, and sex-matched control mice given ordinary tap water. The amount of DMSO consumed increased from a daily average of 27 g/kg/mouse during the first week to 52 g/kg/mouse by the end of the third week. Significant decreases were observed in the treated animals for total body weight, percent spleen weight relative to total body weight, and serum volume, while serum immunoglobulin concentrations remained unchanged. Mice given 4.4 g/kg DMSO intraperitoneally for 7 days, however, revealed significant losses in serum IgG and IgA, but not IgM. The effect of DMSO on the primary humoral response was assessed following immunization of mice with sheep red blood cells either 16 days or 8 weeks after the start of DMSO. Compared with similarly immunized controls, test animals demonstrated moderate, but significant, reductions in both spontaneous and facilitated plaque-forming cells, hemagglutination titres, and serum concentrations of IgG1. Based on a comparison of the two DMSO-treated groups, the degree of immune inhibition increased and the peak of the response was delayed relative to the length of time of DMSO ingestion prior to immunization.

Animals↗

PubMed1982

Selecting drug combinations for treatment of drug-resistant mycobacterial diseases.

Mixtures of antituberculosis drugs were evaluated for their in vitro effects on drug-resistant isolates of Mycobacterium tuberculosis and M. avium-intracellulare. The response of individual isolates to representative drug combinations was not always predictable from the results of single-drug sensitivity assays. For the case of M. tuberculosis, combinations of drugs were often bactericidal even under conditions where two or more drugs were without effect when tested singly. The more widely drug-resistant M. avium-intracellulare demonstrated increased growth inhibition when subcultured in the presence of single drugs, particularly rifampin and streptomycin. However, these conditions favored the selection of highly resistant strains. Alternatively, multiple drugs were often bacteriostatic; and under conditions where isolates demonstrated growth inhibition, the selection of highly drug-resistant strains was delayed. These results suggest a role for multiple-drug sensitivity assays in selecting drug combinations to be used in the treatment of drug-resistant mycobacterioses.

Antitubercular Agents↗

PubMed1982

In vitro drug sensitivity of M. avium-intracellulare complex in the presence and absence of dimethyl sulphoxide.

In vitro growth inhibition of 27 drug resistant isolates of M. avium-intracellulare was compared following continuous culture in the presence of single drugs alone and in combination with 2.5% dimethyl sulphoxide. In the absence of DMSO, 63% of the isolates were inhibited by rifampin and streptomycin, 19% by isoniazid and ethambutol and 4% by ethionamide. Addition of DMSO increased the number of isolates demonstrating growth inhibition by 26-30% for all drugs except ethionamide (11%). The growth inhibitory effect of each drug, whether assayed alone or in combination with DMSO, varied considerably for each strain. Three isolates were inhibited only in the presence of DMSO plus a drug, six isolates demonstrated growth inhibition without any enhanced effect due to DMSO, while the remaining eighteen isolates were sensitive to at least one drug in the presence of DMSO and to different drugs in the absence of DMSO.

Antitubercular Agents↗

PubMed1981

Serum protein concentrations and respiratory tract abnormalities following short-term exposure to amosite: a comparison between former asbestos workers and unexposed controls.

A group of 176 former asbestos workers and 76 unexposed controls of similar age were evaluated and compared for concentrations of serum immunoglobulins, alpha 1-antitrypsin, carcinoembryonic antigen (CEA), pulmonary function, radiographic appearance of the lungs, rales, cellular atypia and ferruginous bodies in sputum, and smoking habits. Test subjects were evaluated as a single group and also according to years of exposure to asbestos. Both test and control populations were independently subjects to parametric and nonparametric correlation analyses. Partial correlations were also determined for both groups after controlling for age, race, sex and smoking habits. Analysis of variance was used to compare test and control groups. Smoking, particularly heavy smoking, was an important variable influencing abnormalities of the respiratory tract and CEA in former asbestos workers but not in controls. Except for immunoglobulin A (IgA), serum proteins, CEA, and alpha 1-antitrypsin were not significantly different between test and control subjects. Analysis of variance revealed significant increases between test and control groups for cellular atypia, X-ray abnormalities, rales, and pulmonary restriction. Partial correlation analysis of the asbestos-exposed group revealed important correlations between ferruginous bodies in sputum, rales, and radiographic appearance of the lungs.

Adult↗

PubMed1980

Urine calcitonin levels in patients with bronchogenic carcinoma.

We demonstrated previously that high serum calcitonin values in bronchogenic carcinoma are useful clinically as a parameter of progress of the disease and response to therapy. After developing a procedure for the measurement of calcitonin in urine, we studied serum and urine levels in 41 patients with lung cancer, using both a carboxyl terminus and a midportion recognizing antiserum. In general, midportion antiserum was more useful. Urine calcitonin measurements alone were superior to serum in terms of numbers of patients having increased values with one or both antisera (76% vs 46%). When both antisera were used to assay both serum and urine, 90% of patients had abnormal values. Once a tissue diagnosis has been established, the radioimmunoassay of urinary calcitonin offers a new dimension to the utility of this hormone as a marker for bronchogenic carcinoma.

Adenocarcinoma↗

PubMed1980

Anergy in active pulmonary tuberculosis. A comparison between positive and negative reactors and an evaluation of 5 TU and 250 TU skin test doses.

Based on induration of less than 10 mm at 48 and 72 hours, 49 of 200 (25 percent) patients with active pulmonary tuberculosis failed to respond to intermediate (5TU) strength PPD. Distribution of reactors vs nonreactors was similar with regard to sex but not race, with more white subjects proving to be nonreactive. Additional comparisons between the two groups revealed significantly higher values in the responder population for age, in vitro lymphocyte response to PPD, total serum protein and serum IgG. Responsiveness of lymphocytes to phytohemagglutinin was also increased in this group, but only at lower mitogen concentrations. Alternatively, the nonresponder group demonstrated higher values for alpha-1 globulins. A group of nontuberculous patients similarly subjected to skin testing showed negative reactivity to 5 TU PPD at the much higher incidence of 152/173 (88 percent). The 49 patients with pulmonary tuberculosis and 152 nontuberculous patients who did not respond to 5 TU PPD were further tested with 250 TU PPD. In the group with tuberculosis, 30/49 (61.2 percent) demonstrated positive reactions, whereas only 55/152 (36.2 percent) nontuberculous patients showed induration equal to 10 mm or higher. Skin testing with the recall antigens TOE and SK-SD indicated that only 3/200 (1.5 percent) tuberculous patients could be classified as being anergic; 9/200 (4.5 percent) were specifically anergic to PPD and 7/200 (3.5 percent) demonstrated questionable anergy to PPD as judged by a 250 TU PPD response that was greater than 5 but less than 10 mm.

Adult↗

PubMed1980

Pretreatment, prediagnosis immunoglobulin, and alpha 1-antitrypsin levels in patients with bronchial carcinoma.

Sera from 148 patients suspected of having bronchial carcinoma were evaluated for concentrations of IgA, IgM, IgG, and alpha 1-antitrypsin (alpha 1-AT). Histologically, 137 tumor specimens obtained by bronchoscopy or surgical biopsy were diagnosed as squamous cell carcinoma (55%), adenocarcinoma (18%), undifferentiated small cell carcinoma (20%), or undifferentiated large cell carcinoma (7%). The tumor types of the remaining 11 patients were not identifiable from the records but were included as a separate group. Serum protein values were compared with those of a control group of 60 healthy adult volunteers. Regression analysis of age, race, and sex effects on the results of comparisons between test and control groups indicated that, with the possible exception of age and IgM, these three independent variables did not significantly influence the observations. Both serum IgA and alpha 1-AT were significantly elevated in all tumor groups when compared to the control levels. This was not the situation for serum IgG. Results for serum IgM were equivocal and depended on the statistical methods used. Although the serum immunoglobulin concentrations for the small cell carcinoma group were consistently lower than those for the other tumor cell types, no statistically significant difference existed between the five tumor groups in this regard.

Age Factors↗

PubMed1979

Induction of aryl hydrocarbon hydroxylase by lymphocytes from women taking oral contraceptives.

The peripheral blood lymphocytes (PBL) from two female subjects were assayed for AHH induction 40 days prior to and 30 days during ingestion of progesterone and estrogen analogues as oral contraceptives. Three habitual users of oral contraceptives were also studied. No in vitro inhibition of AHH induction was observed as a consequence of the use of these hormone analogues. Values obtained for enzyme activity suggest a slight increase in AHH induction resulting from the use of oral contraceptives. Further studies with larger numbers of subjects are required before the apparent increase in enzyme inducibility can be considered significant.

Aryl Hydrocarbon Hydroxylases↗