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At least 1,063 records · Page 59Linked to original sources
PubMed1971

Improved medium for enumeration of Clostridium perfringens.

An improved selective medium, Tryptose-sulfite-cycloserine (TSC) agar, for the enumeration of Clostridium perfringens is described. It consists of the same basal medium as Shahidi-Ferguson-perfringens (SFP) agar, but with 400 mug of D-cycloserine per ml substituted for the kanamycin and polymyxin. Tolerance of C. perfringens for D-cycloserine, its production of lecithinase, and its ability to reduce sulfite were used as the basis for development of this medium. Comparisons were made between TSC and SFP agars for the recovery of vegetative cells of C. perfringens by using statistical methods. The results showed that TSC allowed virtually complete recovery of most of the C. perfringens strains while inhibiting practically all facultative anaerobes tested. SFP agar allowed a slightly higher rate of recovery of C. perfringens but was found to be much less selective.

Agar↗
PubMed1971

Role of autolysins in the killing of bacteria by some bactericidal antibiotics.

The rapid lysis of Bacillus licheniformis NCTC 6346 and B. subtilis 168 trp caused by vancomycin and d-cycloserine can be inhibited by stopping protein synthesis. Protein synthesis must be stopped for more than one doubling time of the cells before addition of wall inhibitors. Poorly lytic mutants (lyt(-)) of B. licheniformis required 10 to 20 times the concentration of vancomycin or cycloserine to be added to growing cultures to cause even slow lysis. At lower concentrations growth of the mutants is stopped, but the bacteria remain fully viable. Sensitivity of mucopeptide synthesis to vancomycin is the same in both mutants and parent. Sensitivity to the action of d-cycloserine is slightly less in the mutant than in the parent.

Autolysis↗
PubMed1976

In vitro spheroplast and L-form induction within the pathogenic nocardiae.

Six strains of Nocardia asteroides, two strains of N. caviae, and two strains of N. braziliensis were grown in medium supplementted with glycine, lysozyme, D-cycloserine, glycine plus lysozyme, and glycine plus D-cycloserine. It was shown that three strains of N. asteroides, and two strains of N. caviae, readily formed spheroplasts and/or protoplasts when grown in the presence of glycine plus either lysozyme or D-cycloserine. This process was studied by both phase contrast microscopy and electron microscopy. The induced cultures were then plated on hypertonic medium for the isolation of L-forms. It was shown that the organisms differed greatly in their ability to produce spheroplasts and subsequently grew as L-forms or transitional-phase variants.

Culture Media↗
PubMed1975

Drug absorption in patients with T-tube after cholecystectomy.

The influence of bile flow on the absorption of tetracycline, doxycycline, sulphadimidine and cycloserine was studied in 13 volunteer patients with t-tubes in their main bile ducts after biliary surgery. Their hepatic functions and bile flows were estimated by giving I131 radioiodinated rose-bengal intravenously. About 80% radioactive tracer was recovered from the bile when the t-tube was open, so most of the bile was diverted outside the intestinal tract. Up to 4 hours after administration serum tetracycline levels were lower when the t-tube was open than when the t-tube was closed. In one patient the serum levels were so much reduced that therapeutic serum tetracycline levels could not be achieved. The serum doxycycline levels were fairly high and bile flow did not have any effect on absorption. The 24-hour biliary excretion of doxycycline was only about 15% of the urinary excretion. The absorption of sulphadimidine and cycloserine was not affected by the presence or absence of bile. The bile salts are important surfactants in man, and modify the absorption rate of tetracycline, but not of doxycycline, sulphadimidine and cycloserine. Even in the absence of intact bile flow therapeutic serum tetracycline levels can be expected with the doses currently used.

Adult↗
PubMed1992

[The validation of the adequacy of chemotherapy in bladder tuberculosis based on a study of bacteriostatic activity].

Study of the bacteriostatic activity (BA) of the blood, urine and tissue of the tuberculosis-affected urinary bladder after the administration of two tuberculostatic combinations (isoniazid + cycloserine and isoniazid + rifampicin) has demonstrated the difference in the BA curves that were formed in the above media. Use of isoniazid + cycloserine gives rise to a high BA level by 6-9 h with further gradual decrease of the parameters. The combination of isoniazid + cycloserine produces a typical double-humped curve with titre prolongation. The data obtained give evidence on the experience of the use of the first combination of the preparations in patients with fresh circumscribed urinary bladder lesions. The second combination (isoniazid + rifampicin) is indicated in the presence of ulcerous-cicatricial changes in association with a more prolonged circulation of the preparations in the organism (specific features of rifampicin metabolism).

Blood Bactericidal Activity↗
PubMed1997

Anxiolytic activity of glycine-B antagonists and partial agonists--no relation to intrinsic activity in the patch clamp.

On the basis of animal models, anxiety was one of the first suggested clinical applications of partial agonists of the glycineB site coupled to the NMDA receptor. It is not certain, however, whether these findings can be extended to full glycineB antagonists and what is the relation between intrinsic activity (degree of NMDA receptor antagonism) and anxiolytic effect. In the present study several NMDA receptor antagonists, including several glycineB antagonists/partial agonists, were tested for anxiolytic activity in the Vogel conflict test and the elevated plus-maze. Additionally, the intrinsic activities of the glycineB partial agonists used [ACPC, (R,+)-HA-966 and D-cycloserine] were compared in patch-clamp experiments in cultured neurones. In the plus-maze the most striking increase in the time spent in open arms (index of anxiolytic effect) was seen after diazepam and D-cycloserine (at doses that did not change locomotion). Also reliable (dose-dependent), although weaker, anxiolytic activity was produced by the uncompetitive NMDA receptor antagonist (+)MK-801 and the competitive antagonist CGP 39551. Modest anxiolytic-like effect in the plus-maze was also observed after the glycineB antagonist L-701,324 and the partial agonist (+,R)-HA-966. Uncompetitive antagonists memantine and amantadine, the glycineB partial agonist ACPC (up to 600 mg/kg) or the full antagonists MRZ 2/570, MRZ 2/571 and MRZ 2/576 had no effect. In the Vogel conflict test neither memantine, nor any of the full glycineB antagonists tested (L-701,324 and MRZ 2/576), showed anxiolytic activity. Patch-clamp studies revealed that the intrinsic activity of (+,R)-HA-966, D-cycloserine and ACPC was 13, 57 and 92%, respectively, as compared to that of glycine itself (100%). In conclusion, for the agents tested there is no clear relation between the levels of intrinsic activity, i.e. degree of NMDA receptor inhibition, and anxiolytic activity. Moreover, L-701,324 and MRZ-type glycineB full antagonists do not exchibit anxiolytic activity in the elevated plus-maze and Vogel conflict test.

Animals↗
PubMed2002

Role of NMDA receptors and MAP kinase in the amygdala in extinction of fear: clinical implications for exposure therapy.

Infusions into the amygdala (a brain area essential for excitatory fear conditioning) of either NMDA receptor antagonists or inhibitors of the NMDA receptor-linked mitogen activated protein kinase cascade block extinction learning. Conversely, the NMDA receptor agonist D-cycloserine facilitates extinction after either systemic administration or intra-amygdala infusion. Because therapeutic interventions based on extinction procedures are commonly used to treat fear disorders, and because D-cycloserine is a widely available and safe compound, D-cycloserine or similar agents might be usefully combined with traditional extinction-based approaches in the treatment of clinical fear.

Amygdala↗
PubMed2006

Cell wall-inhibitory antibiotics activate the alginate biosynthesis operon in Pseudomonas aeruginosa: Roles of sigma (AlgT) and the AlgW and Prc proteases.

A bioassay was developed to identify stimuli that promote the transcriptional induction of the algD operon for alginate biosynthesis in Pseudomonas aeruginosa. Strain PAO1 carried the algD promoter fused to a chloramphenicol acetyl-transferase cartridge (PalgD-cat), and > 50 compounds were tested for promoting chloramphenicol resistance. Most compounds showing PalgD-cat induction were cell wall-active antibiotics that blocked peptidoglycan synthesis. PalgD-cat induction was blocked by mutations in the genes for sigma22 (algT/algU) or regulators AlgB and AlgR. Anti-sigma factor MucA was the primary regulator of sigma22 activity. A transcriptome analysis using microarrays verified that the algD operon undergoes high induction by D-cycloserine. A similar sigma(E)-RseAB complex in Escherichia coli responds to envelope stress, which requires DegS protease in a regulated intramembrane proteolysis (RIP) cascade to derepress the sigma. Mutant phenotypic studies in P. aeruginosa showed that AlgW (PA4446) is likely to be the DegS functional homologue. A mutation in algW resulted in a complete lack of PalgD-cat induction by D-cycloserine. Overexpression of algW in PAO1 resulted in a mucoid phenotype and alginate production, even in the absence of cell wall stress, suggesting that AlgW protease plays a role in sigma22 activation. In addition, a mutation in gene PA3257 (prc), encoding a Prc-like protease, resulted in poor induction of PalgD-cat by D-cycloserine, suggesting that it also plays a role in the response to cell wall stress.

Alginates↗
PubMed2003

Role of the amygdala in fear extinction measured with potentiated startle.

Although much is now known about the neural basis of excitatory fear conditioning, much less is known about the neural basis of inhibitory conditioning. One type of inhibitory conditioning is extinction, a process in which stimuli that elicit fear by virtue of previous associations with aversive stimuli such as shock (excitatory fear conditioning) are now presented in the absence of the aversive stimuli (extinction training). As a result, the ability of the conditioned stimulus to elicit fear gradually diminishes. Extinction is different from forgetting and does not reflect an erasure of the original fear memory. Instead, extinction is an active form of inhibitory learning that competes with excitatory fear conditioning. Infusions into the amygdala (a brain area essential for excitatory fear conditioning) of either NMDA receptor antagonists or inhibitors of the NMDA-receptor-linked mitogen-activated protein kinase cascade block extinction learning. Conversely, the NMDA receptor agonist D-cycloserine facilitates extinction after either systemic administration or intra-amygdala infusion. Because therapeutic interventions based on extinction procedures are commonly used to treat fear disorders, and because D-cycloserine is a widely available and safe compound, D-cycloserine or similar agents might be usefully combined with traditional extinction-based approaches in the treatment of clinical fear.

Amygdala↗
PubMed1977

Growth inhibition of Escherichia coli W by D-norvalyl-D-alanine: an analogue of D-alanine in position 4 of the peptide subunit of peptidoglycan.

Position 4 analogues of d-alanine in the peptide subunit of uridine 5'-diphosphate-N-acetylmuramyl-Ala(1)-dGlu(2)- Lys(3)-dAla(4)-dAla(5) have a significant inhibitory effect on penicillin-sensitive peptidoglycan synthesis in Gaffkya homari (C. V. Carpenter, S. Goyer, and F. C. Neuhaus, 1976). The specificity profile of this in vitro system has been used as a basis for designing analogues with potential antibacterial activity. To circumvent the specificity determinants exerted by d-alanine:d-alanine ligase (adenosine 5'-diphosphate), attention was directed to dd-dipeptides of the type d-alanyl-analogue-d-alanine as a method for incorporating analogues into position 4 of the peptide subunit in vivo. Of the three dipeptides, dAbu-dAla, dNva-dAla, and dVal-dAla, only dNva-dAla (5 x 10(-4) M) inhibited the growth of Escherichia coli W in the presence of 5 x 10(-6) M d-cycloserine. This concentration of d-cycloserine did not inhibit growth, but it potentiated the bactericidal activity of the dipeptide. The lack of antibacterial activity observed with dAbu-dAla and dVal-dAla was correlated with the poor ability of these dipeptides to be taken up via the dipeptide transport system of this organism. Prevention of lysis induced by dNva-dAla plus d-cycloserine by certain dipeptides and not by others supported this correlation. It is proposed that the d-norvalyl residue of the dipeptide is incorporated in vivo into position 4 of the peptide subunit of peptidoglycan, and that this subunit is not an effective substrate in the reaction(s) catalyzed by the penicillin-susceptible enzyme(s) of cross-linked peptidoglycan synthesis.

Alanine↗
PubMed1970

Cell Wall Synthesis by Chlamydia psittaci Growing in L Cells.

Biochemical events accompanying changes in structure and behavior of the cell walls of Chlamydia psittaci strain 6BC during its developmental cycle in L cells (mouse fibroblasts) were studied by measuring at short intervals the effect of d-cycloserine and penicillin G on incorporation of labeled intermediates into acid-insoluble fractions of infected L cells in which host incorporation had been inhibited by cycloheximide and into intact chlamydial cells and cell walls separated from the infected L cells. d-Cycloserine enhanced the incorporation of (14)C-l-alanine at all times in the developmental cycle, but the incorporation of (14)C-l-lysine was always inhibited. In parallel experiments, penicillin G had no effect on incorporation of any of these intermediates, but when infected L cells incorporated (14)C-l-alanine in the presence of penicillin G, the labeled alanine was released more rapidly in the subsequent absence of the antibiotic than in its continued presence. When either penicillin G or d-cycloserine was present throughout the developmental cycle, C. psittaci continued to synthesize deoxyribonucleic acid and protein, but at less than normal rates.

Journal Article↗
PubMed1962

COMPARISON OF SPHEROPLAST INDUCTION IN ALCALIGENES FAECALIS BY THREE DIFFERENT AGENTS.

Lark, Cynthia (Saint Louis University, St. Louis, Mo.) and Robert Schichtel. Comparison of spheroplast induction in Alcaligenes faecalis by three different agents. J. Bacteriol. 84:1241-1244. 1962.-Alcaligenes faecalis strain LB was exposed to different concentrations of cycloserine, d-methionine, or penicillin. The time course of spheroplast induction by these agents was measured as a function of their concentration. The results were consistent with models in which cycloserine reversibly inhibited an intracellular enzyme, and d-methionine was built into a defective cell-wall unit. Penicillin simulated cycloserine. This was taken as further evidence that penicillin inhibits an enzyme associated with cell-wall synthesis.

Journal Article↗
PubMed2026

MIC-based tuberculosis drug susceptibility testing using Sensititre MYCOTB: a diagnostic accuracy meta-analysis.

Accurate drug susceptibility testing (DST) is crucial for designing effective regimens for multidrug-resistant (MDR) and pre-extensively drug-resistant tuberculosis (pre-XDR TB). Sensititre MYCOTB enables simultaneous determination of minimum inhibitory concentrations (MICs) for multiple drugs, but its diagnostic performance varies across studies. This meta-analysis evaluated the diagnostic performance of Sensititre MYCOTB for key MDR and pre-XDR TB drugs. The protocol was registered in PROSPERO (CRD420251230599). PubMed, Cochrane, Google Scholar, Scopus, ONOS, Web of Science, ScienceDirect, and registries were systematically searched for studies published between 2010 and 2025. Studies comparing the Sensititre MYCOTB with reference DST for Mycobacterium tuberculosis complex (MTBC) were included. Bias assessment and pooled diagnostic accuracy estimates were generated. Fourteen studies, including 1,728 isolates, were analyzed. Rifampicin and isoniazid demonstrated high sensitivity (0.976 [95% CI: 0.94-0.99] and 0.977 [95% CI: 0.95-0.99]) and specificity (0.958 [95% CI: 0.84-0.98] and 0.957 [95% CI: 0.83-0.99], respectively) with low heterogeneity. Amikacin, kanamycin, and ofloxacin demonstrate good diagnostic accuracy, with high specificity (>0.98 [95% CI]). Moderate diagnostic accuracy was observed for ethambutol, streptomycin, ethionamide, and rifabutin. Cycloserine, moxifloxacin, and para-aminosalicylic acid showed inconsistent performance despite excellent specificity (>0.97 [95% CI]). Sensitivity analysis partially improved pooled sensitivity for moxifloxacin 0.801 (95% CI: 0.585-0.924) and para-aminosalicylic acid 0.76 (95% CI: 0.518-0.894), whereas cycloserine remained at 0.436 (95% CI: 0.190-0.725), although heterogeneity persisted. Sensititre MYCOTB DST demonstrates high diagnostic accuracy for MDR-TB and pre-XDR-TB drugs, while caution is required with cycloserine, moxifloxacin, and para-aminosalicylic acid. These findings support the integration of MIC-based testing into clinical decision-making.

Microbial Sensitivity Tests↗
PubMed1989

Comparison of media for screening of diarrheic stools for the recovery of Clostridium difficile.

Recoveries of Clostridium difficile from stool specimens by using three media, cycloserine-mannitol agar (M-CMA), cycloserine-mannitol-blood agar (M-CMBA), and cycloserine-cefoxitin agar (M-CCA), were compared. Of 321 clinical specimens, 37 yielded C. difficile. Thirty-four were positive on M-CCA, 21 were positive on M-CMA, and 20 were positive on M-CMBA. M-CCA recovered significantly more C. difficile than did M-CMBA or M-CMA.

Clostridium↗
PubMed1992

Comparison of selective media for optimal recovery of Clostridium difficile from diarrhoeal stools.

Five selective media were compared for their efficacy in the recovery of C. difficile from stool specimens. Of 341 diarrhoeic stool samples, 38 (11%) yielded C. difficile. Eighty per cent of the isolates were detected on modified taurocholate cycloserine cefoxitin fructose agar (MTCCFA) and 73 per cent were detected on taurocholate cycloserine cefoxitin fructose agar (TCCFA). MTCCFA was also found superior to the other four media as it supported better growth of C. difficile colonies, by effectively suppressing the competing microflora. These results suggest that the recovery rate of C. difficile could be enhanced when routine media, incorporated with taurocholate and lower concentration of cycloserine and cefoxitin, is used for the isolation of C. difficile from diarrhoeic stool.

Clostridioides difficile↗
PubMed1981

Effects of pyruvate and other metabolites on cyclic GMP levels in incubations of rat hepatocytes and kidney cortex.

Pyruvate increased cyclic GMP levels in rat hepatocytes. The effects were observed without or with 1-methyl-3-isobutylxanthine. Lactate, acetate, oxaloacetate, alpha-ketoglutarate, succinate, acetoacetate and beta-hydroxybutyrate also increased cyclic GMP levels. Some compounds increased cyclic GMP in kidney cortex slices. The effects were dependent upon Ca2+ in the medium. Cyclic AMP was increased 30-50% by some of these substances with 2.6 mM Ca2+. Rotenone, oligomycin, antimycin, dinitrophenol, KCN, and arsenate decreased GTP and ATP, basal cyclic GMP and the pyruvate effect, but did not alter cyclic AMP. Although fluoroacetate alone had no effect on cyclic nucleotides, GTP, or ATP, it potentiated the pyruvate effect on cyclic GMP. Adenosine and guanosine increased cyclic GMP and GTP to a similar extent of 30-50%. Aminooxyacetate, cycloserine, pentenoic acid and mepacrine decreased the pyruvate effect while cycloserine or mepacrine alone increased cyclic GMP. Citrate and mepacrine inhibited soluble and particulate guanylate cyclase from rat liver while cycloserine and acetoacetate increased guanylate cyclase activity. None of the other compounds altered guanylate cyclase activity. These results indicate that various metabolites and inhibitors can alter cyclic GMP accumulation in hepatocytes and renal cortex slices. Several mechanisms may be involved in these effects.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Tuberculosis susceptibility patterns, predictors of multidrug resistance, and implications for initial therapeutic regimens at a New York City hospital.

BACKGROUND: Multidrug resistance has complicated tuberculosis therapy. We studied antibiotic susceptibilities of Mycobacterium tuberculosis and predictors of multidrug resistance to assist in determining initial drug regimens. METHODS: We conducted a case-control study based on chart review of patients with and without multidrug-resistant tuberculosis, including outpatients and inpatients with culture-proved tuberculosis seen at a large New York, NY, hospital during 1991 and 1992. Patient characteristics studied included serologic findings for human immunodeficiency virus and the presence of the acquired immunodeficiency syndrome. Descriptive analysis considered potential initial drug regimens. A theoretically effective regimen was assumed to contain at least two drugs to which an isolate was susceptible. RESULTS: For 172 patients, 28.5% of isolates were resistant to isoniazid, at least 20.9% to rifampin, 15.7% to ethambutol, 8.1% to pyrazinamide, 18.6% to streptomycin, 9.9% to ethionamide, 8.1% to kanamycin, and none to capreomycin, cycloserine, and ciprofloxacin; 18.6% were resistant to both isoniazid and rifampin. Chart review of 159 patients showed that acquired immunodeficiency syndrome, human immunodeficiency virus seropositivity, female gender, residence in the Bronx, and race were associated with multidrug resistance. The four-drug regimen of isoniazid, rifampin, ethambutol, and pyrazinamide was theoretically effective for 81% to 85% of patients. No subset of patients would have a markedly better theoretical benefit from that regimen. Only five- or six-drug regimens that used the combinations of capreomycin plus ciprofloxacin, capreomycin plus cycloserine, ciprofloxacin plus cycloserine, or all three drugs together theoretically offered significantly higher effectiveness. CONCLUSIONS: Tuberculosis isolates at our hospital have a high frequency of multidrug resistance. Only five- or six-drug regimens are theoretically adequate as initial therapy for our patients.

AIDS-Related Opportunistic Infections↗
PubMed1997

Enhancement of intermediate-term memory by an alpha-1 agonist or a partial agonist at the glycine site of the NMDA receptor.

The aim of the present study was to investigate whether the activation of alpha-1 adrenergic receptors can influence intermediate-term memory. Therefore, the effects of ST 587 (30 or 100 micrograms/kg), a putative alpha-1 agonist, on the retention of the radial arm task using non-matching to sample with a 4-h delay were investigated in rats. The results indicated that the administration of ST 587 (100 micrograms/kg) before a sampling phase increased the time to complete the sampling phase which was due to an increased number of errors of repetition (regarded as working memory errors) and a reduced number of arms visited in a given time (regarded as behavioral activity). However, this treatment increased the number of correct choices before the first error during the retention phase in this task. Since we were also interested in investigating the role of NMDA receptors in memory encoding, we investigated whether NMDA receptor modulation by d-cycloserine (1 or 10 mg/kg), a partial agonist of the glycine site on the NMDA receptor, had any influence on the performance of rats in this task. The results indicated that d-cycloserine (10 mg/kg) given before the sampling phase did not influence the performance of rats during the sampling phase, but it did improve their choice accuracy during the retention phase of this task. These data suggest that the systemic administration of either an alpha-1 agonist or an indirect agonist of NMDA receptors can facilitate intermediate-term retention of spatial information.

Adrenergic alpha-Agonists↗