John S. Bergmann

Thrombin peptide, TP508, stimulates angiogenic responses in animal models of dermal wound healing, in chick chorioallantoic membranes, and in cultured human aortic and microvascular endothelial cells

The alpha-thrombin peptide, TP508, accelerates the healing of full-thickness wounds in both normal and ischemic skin. In wounds treated with TP508, a pattern of increased vascularization is consistently observed both grossly and microscopically when compared to wounds treated with saline. One possible mechanism by which the peptide accelerates wound healing is by promoting revascularization of granulation tissue at the injured site. To evaluate the angiogenic potential of TP508, the peptide was tested in the chick embryo chorioallantoic membrane (CAM), where it increased the density and size of CAM blood vessels relative to controls. Additionally, TP508 stimulated chemokinesis and chemotaxis in a dose-dependent fashion in cultured human aortic and human microvascular endothelial cells. Taken together, these in vivo and in vitro data support an angiogenic role for TP508 in wound healing. A working model is presented to explain how this 23-amino-acid peptide, which lacks proteolytic activity, is generated during wound healing and contributes to the nonproteolytic functions associated with alpha-thrombin during tissue repair.

Cocaine and dopamine differentially protect [3H]mazindol binding sites from alkylation by N-ethylmaleimide

The binding of cocaine, d-amphetamine and dopamine to the site on the dopamine transporter labeled by [3H]mazindol was investigated in rat striatal membranes. N-Ethylmaleimide inhibited about 95% of the specific binding of 5 nM [3H]mazindol in a concentration-dependent manner. The effect of 10 mM N-ethylmaleimide was completely prevented by cocaine (EC50 of 3 microM), but neither 300 microM dopamine nor d-amphetamine afforded any significant protection. On the other hand, high concentrations of cocaine, d-amphetamine and dopamine provided similar protection against inhibition by 0.1 mM N-ethylmaleimide. Taken together these data support the hypothesis that a significant portion of the cocaine binding domain on the transporter is distinct from that of either dopamine or amphetamine. This distinction may be sufficient to allow properly designed drugs to prevent cocaine binding without inhibiting DA transport.

Traumatic brain injury reduces hippocampal high-affinity [3H]choline uptake but not extracellular choline levels in rats

Hippocampal cholinergic hypofunction may contribute to memory deficits following experimental traumatic brain injury. These studies examined two important factors in acetylcholine synthesis: choline availability and neuronal uptake. No reductions in basal extracellular choline levels, using microdialysis, were observed 2 weeks after cortical impact injury. However, studies of high affinity [3H]choline uptake in the hippocampus, measured in a synaptosomal preparation, found a reduction in the maximum velocity of choline uptake (Vmax), while no differences in affinity constants (Km) were found. The results suggest that post-traumatic cholinergic deficits are not attributable to decreased availability of choline, but may be associated with either a decreased ability of cholinergic neurons to take up choline and/or a loss of cholinergic neurons.

Clinical Evaluation of the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test for Rapid Detection of Mycobacterium tuberculosis in Select Nonrespiratory Specimens

ABSTRACT The performance of the Amplified Mycobacterium Tuberculosis Direct Test (MTD; Gen-Probe, Inc., San Diego, Calif.) for rapid diagnosis of extrapulmonary tuberculosis was evaluated by testing 178 nonrespiratory specimens from 158 patients. Criteria for specimen inclusion were (i) a positive smear for acid-fast bacilli (n = 54) and (ii) the source if the smear was negative (tissue biopsies and aspirates and abscess material were tested; n = 124). Results were compared to those of mycobacterial culture; clinical history was reviewed when MTD and culture results disagreed. Forty-eight specimens (27.0%) were positive for mycobacteria, including 23Mycobacterium tuberculosis complex specimens; of which 21 were smear positive. Twenty-five specimens were MTD positive; 20 of these grew M. tuberculosis complex. All of the five MTD-positive, M. tuberculosis complex culture-negative specimens were considered truly positive, based on review of the medical record. Of the three MTD-negative, M. tuberculosiscomplex culture-positive specimens, two contained inhibitory substances; one of the two was smear positive. Excluding the latter specimen from analysis, after chart review, the sensitivity, specificity, and positive and negative predictive values of the MTD were 92.6, 100, 100, and 98.7%, respectively, by specimen and 89.5, 100, 100, and 98.6% by patient. Given the few smear-negative samples from patients with extrapulmonary tuberculosis in our study, additional similar studies that include more smear-negative, M. tuberculosis complex culture-positive specimens to confirm our data are desirable.

Mycobacterial growth indicator tube for susceptibility testing of Mycobacterium tuberculosis to isoniazid and rifampin

The reliability of mycobacteria growth indicator tubes (MGIT) for susceptibility testing of Mycobacterium tuberculosis to isoniazid and rifampin was evaluated by comparing MGIT results to those obtained by the radiometric BACTEC TB system. To resolve discrepancies, MGIT and BACTEC TB tests were repeated, and the method of proportion was performed. For the 89 isolates evaluated, there was complete agreement between MGIT and BACTEC results for rifampin: 70 isolates were susceptible, and 19 were resistant. After initial testing of isoniazid, both methods agreed for 85 isolates (95.5%): 72 were susceptible, and 13 were resistant by both methods; 2 were resistant by BACTEC but susceptible by MGIT, and 2 were resistant by MGIT but susceptible by BACTEC. Based on results of discrepant analysis for the latter four isolates, all four were resistant to isoniazid. Thus, MGIT correctly detected susceptibility and resistance to isoniazid for 97.3% and 100% of the isolates, respectively. The mean time to MGIT results was 6.38 +/ 0.11 days (range, 6 to 14 days), compared to a mean of 9.09 +/- 1.90 days (range, 4 to 12 days) for BACTEC (p < .001). MGIT provides a rapid and reliable, nonradiometric alternative to BACTEC for susceptibility testing of M. tuberculosis to isoniazid and rifampin.

Evaluation of the BBL MGIT (Mycobacterial Growth Indicator Tube) AST SIRE System for Antimycobacterial Susceptibility Testing of Mycobacterium tuberculosis to 4 Primary Antituberculous Drugs

OBJECTIVE To evaluate the performance of the BBL MGIT (Mycobacterial Growth Indicator Tube) AST SIRE system for the antimycobacterial susceptibility testing of Mycobacterium tuberculosis to isoniazid (at a concentration equivalent to the lower concentration used for testing by the method of proportion), rifampin, ethambutol, and streptomycin. DESIGN Thirty-one clinical isolates and 30 challenge strains provided by the Centers for Disease Control and Prevention (CDC) were tested by MGIT AST SIRE using 2 methods of inoculum preparation, and results were compared with those of the method of proportion, which was considered the reference method. Clinical isolates for which the results of the 2 methods were discordant also were tested at 2 reference laboratories. RESULTS Based on data from our site and the reference laboratories, agreement rates between initial MGIT AST SIRE results and the method of proportion for the clinical isolates with the inoculum prepared from a McFarland equivalent and from a positive MGIT tube, respectively, were 100% and 96.8% for isoniazid, 100% and 100% for rifampin, 96.8% and 100% for ethambutol, and 100% and 100% for streptomycin, excluding the isolate for which the discordant streptomycin result could not be resolved. For the 30 challenge isolates, agreement rates between MGIT AST SIRE and expected results and between method of proportion and expected results, respectively, were 96.7% and 93.3% for isoniazid, 93.3% and 100% for rifampin, 83. 3% and 100% for ethambutol, and 93.3% and 100% for streptomycin. For the clinical isolates, the mean time to an MGIT AST SIRE result of susceptible was 6.15 +/- 0.13 days (range, 5-8 days). For a result of resistant, the mean time overall was 5.00 +/- 0.24 days (range, 3-8 days). CONCLUSION These data suggest that the MGIT AST SIRE system, using either method of inoculum preparation, is an acceptable alternative to the BACTEC 460 TB method of susceptibility testing of clinical isolates of M tuberculosis to isoniazid, rifampin, ethambutol, and streptomycin. Reasons for the lower agreement with the CDC challenge isolates should be investigated. Further evaluation of the MGIT AST SIRE system using a concentration of isoniazid equivalent to the higher concentration tested by the method of proportion would be useful, because the decision concerning use of this agent generally is based on the susceptibility test result at the higher concentration.

Evaluation of the Enhanced Amplified Mycobacterium Tuberculosis Direct Test for Direct Detection of Mycobacterium tuberculosis Complex in Respiratory Specimens

OBJECTIVE To evaluate the performance of the enhanced Mycobacterium Tuberculosis Direct Test (E-MTD), for the direct detection of M tuberculosis complex (MTBC) in respiratory specimens. DESIGN Two hundred seventy-four respiratory specimens from 151 patients in respiratory isolation were tested with the E-MTD, and the results were compared with the results of mycobacterial smear, culture, and the earlier form of the test, MTD-1. RESULTS Forty-one specimens were culture positive for mycobacteria (20 MTBC and 21 nontuberculous mycobacteria), 23 of which were smear positive (16 MTBC, 7 nontuberculous mycobacteria). Twenty-four specimens were positive by E-MTD, and 21 were positive by MTD-1. Of the 20 MTBC culture-positive specimens, 19 were positive by the E-MTD and 19 were positive by the MTD-1. The remaining specimens were MTBC negative by all methods. After resolution of discrepancies, the sensitivity, specificity, and positive and negative predictive values were 95.2%, 100%, 100%, 99.6% for the MTD-1 and 95.2%, 98.8%, 87.0%, and 99.6%, for the E-MTD. For the E-MTD smear-positive and smear-negative specimens, these same values were 93.8%, 100%, 100%, and 87.5% and 100%, 98.8%, 62.5%, and 100%, respectively. CONCLUSION The results suggest that the E-MTD is a reliable method for the direct detection of MTBC in smear-positive respiratory specimens.

SAR of cocaine: further exploration of structural variations at the C-2 center provides compounds of subnanomolar binding potency

Syntheses of a variety of new analogues of cocaine are reported together with their binding affinities and dopamine uptake inhibition activities. The present work further expands the SAR data base for cocaine.

On the toxicity of the ciguatera producing dinoflagellate, gambierdiscus toxicus adachi and fukuyo isolated from the Florida keys

Abstract The ciguatoxic dinoflagellate, G. toxicus was isolated from Islamorada Key, Florida. Analysis of unialgal cultures indicated that the dinoflagellate produces two toxins: a chloroform soluble toxin and a water soluble toxin. The former toxin was judged to be closely related to ciguatoxin on the basis of TLC and clinical effects manifested in mice. The water soluble toxin was closely related to maitotoxin on the basis of TLC and clinical effects manifested.

Evaluation of the Roche AMPLICOR™ MTB assay for the detection of Mycobacterium tuberculosis in sputum specimens from prison inmates

The reliability of the Roche Mycobacterium tuberculosis polymerase chain reaction (PCR) assay (AMPLICOR MTB) for the diagnosis of pulmonary tuberculosis was evaluated by testing expectorated sputum specimens from 187 inmates in Texas state prisons and comparing the results to culture and medical history. Of the 80 specimens that were culture positive for mycobacteria, 36 specimens from 16 patients grew M. tuberculosis. Forty-six specimens were smear positive for acid-fast bacilli (AFB), and of these, M. tuberculosis was isolated from 24. On initial testing, 52 specimens were PCR positive. Thirty-one of these 52 were culture positive for M. tuberculosis, and 21 were culture negative, resulting in a PCR sensitivity and specificity of 86.1 and 96.1%, respectively. After resolving discrepancies by review of the medical history and repeat testing, PCR sensitivity, specificity, and positive and negative predictive values, respectively, were 92.8, 99.8, 98.1, and 99.2%. For AFB smear-positive specimens, the sensitivity, specificity, and positive and negative predictive values, were 95.8, 100, 100, and 93.3, respectively; whereas, for AFB smear-negative specimens, these values were 87.5, 99.7, 95.5, and 99.4%, respectively. These results confirm the reliability of the AMPLICOR MTB assay for direct detection of M. tuberculosis in AFB smear-positive sputum specimens and suggest a potential role in evaluating AFB smear-negative sputum specimens.