In Vitro Susceptibility of Atypical Mycobacteria To Rifampin

Atypical mycobacteria (209 strains) were examined for susceptibility to rifampin by the proportion method by using Middlebrook 7H-10 agar. All strains of Mycobacterium kansasii and tap-water scotochromogens were inhibited by 0.25 to 1 μg of the drug per ml. Seventy-six per cent of M. scrofulaceum and 61% of M. intracellulare strains were susceptible to 4 μg/ml or less; 5% of the former and 8% of the latter were resistant to 16 μg/ml. All strains of M. gastri and M. triviale and most strains of M. terrae were sensitive to 1 to 4 μg/ml. Two strains of M. borstelense were both inhibited by 8 μg/ml. Nearly all strains of M. fortuitum were resistant to the drug. The results of this study suggest that rifampin may be a valuable agent for the treatment of many atypical mycobacterial infections.     

In Vitro Effects of Some Chemotherapeutic Agents on Mycobacteria

Examination of the bactericidal and bacteriostatic effects of nine antibiotics on atypical mycobacteria revealed that streptovaricin complex and streptovaricin C exerted bactericidal effects on several strains in concentrations lower than 1.0 mug/ml. An exposure to the drug for 48 hr at 37 C was necessary to effect a complete inactivation of more than 99.9% of the exposed microorganisms. The appearance of strepto-varicin-resistant mutants was observed. However, these mutants were unstable, and reversion to streptovaricin susceptibility occurred. Celesticetin salicylate, added in a concentration of 100.0 mug/ml to the medium of Olitzki and Gershon inoculated with Mycobacterium leprae, effected a complete change of the uniformly stained mycobacteria to bipolarity, which indicates the devitalization of this microorganism.     

Antimycobacterial Activity of Rifampin Under In Vitro and Simulated In Vivo Conditions

Minimal inhibitory concentrations of rifampin for different species of mycobacteria were determined in 7H-10 agar medium and Lowenstein-Jensen egg medium. When rifampin was incorporated into egg medium, approximately 90% of its activity was lost. The stability of rifampin was tested during storage at different temperatures and concentrations. When tested in agar medium, a combination of isoniazid (INH) and rifampin inhibited multiple drug-resistant strains of Mycobacterium intracellulare, but under simulated in vivo conditions the drugs did not eliminate these same organisms. Drug-resistant mutants of M. intracellulare multiplied during an 8-day period when exposed 10 hr daily to the INH-rifampin regimen. However, combinations of rifampin and INH reduced drug-resistant mycobacterial populations by 99%, an effect which could not be enhanced by the addition of either erythromycin, ethionamide, or cycloserine.     

In Vitro Susceptibility of Strains of Pseudomonas pseudomallei to Rifampin

Reported high activity of rifampin for Pseudomonas pseudomallei could not be verified by extensive in vitro tests conducted with 31 recently isolated strains. Minimal inhibitory concentrations of rifampin were 25 μg/ml for three strains and greater than 25 μg/ml for 28 strains. Rifampin had relatively poor in vitro activity when compared with tetracycline drugs and chloramphenicol antibiotics now commonly used for treating melioidosis.     

Susceptibility In Vitro and In Vivo of Pseudomonas pseudomallei to Rifampin and Tetracyclines

Tests were performed on 64 strains of Pseudomonas pseudomallei to compare rifampin, various tetracyclines, and other antibiotics for inhibitory activity in vitro. Rifampin minimum inhibitory concentration (MIC) values generally fell between 25 to 50 μg/ml. For deoxycycline, methacycline, tetracycline, and minocycline, MIC means ranged from 1.3 to 2.7 μg/ml. Delayed treatment tests in subacute mouse infections revealed a better rifampin activity than was expected from its weak activity in vitro, whereas of the others, minocycline appeared superior. None of these five antibiotics demonstrated fully curative effectiveness in terms of mouse survival or eradication of residual infection in organs.     

In Vitro Effect of Ozagrel on Mushroom Tyrosinase

This investigation, in vitro, shows that ozagrel, an antithrombotic drug, inhibited both monophenolase and diphenolase activities of mushroom tyrosinase when l-tyrosine and l-DOPA were assayed spectrophotometrically, respectively. The IC₅₀ values, for monophenolase and diphenolase activities, were 1.35 and 3.45 mM, respectively. Ozagrel was estimated to be a reversible mixed-type inhibitor of diphenolase activity with the constants (K _S1, K _S2, K _i1, and K _i2) determined to be 2.21, 3.89, 0.454, and 0.799 mM, repectively. Increasing ozagrel concentrations provoked longer lag periods as well as a concomitant decrease in the monophenolase activity. Inhibition experiment demonstrated that ozagrel bound the enzyme at a site distincted from the substrate active site, but it bound to either E (Enzyme) or ES (Enzyme-Substrate) complex.     

Effect of RA233 on Platelet Function In Vitro

RA233, a new pyrimido-pyrimidine compound, is a powerful inhibitor of platelet function tested in vitro; it inhibits calcium and adenosine diphosphate (A.D.P.)-induced platelet aggregation, inhibits the retention of platelets by glass beads, decreases the release of platelet factor 3 by kaolin, and inhibits clot retraction. In some in-vitro systems RA233 is significantly more potent that its analogue RA433 in inhibiting platelet function.     

Effect of pH on In Vitro Phagocytosis of Streptococcus pyogenes

Phagocytosis experiments were performed with mouse peritoneal leucocytes (MPL). The natural pH of the mouse peritoneal cavity was found to be between 6.1 and 6.3. The phagocytic and intracellular killing activities of MPL by pH variations was studied. It was observed that the optimal ingestion and intracellular killing of bacteria is at the natural pH of the peritoneal cavity.     

Effect of Micronutrients on Methylglyoxal-Mediated In Vitro Glycation of Albumin

Nonenzymatic glycation of long-lived proteins has been implicated in several complications related to age and diabetes. Dicarbonyl compounds such as methylglyoxal (MGO) have been identified as the predominant source for the formation of advanced glycation end-products (AGEs) in various tissues. We investigated the effect of 13 micronutrients on MGO-mediated in vitro glycation of bovine serum albumin (BSA), as formation of AGEs and protein carbonyls. BSA (10 mg/ml) was incubated at 37°C with 100 mM MGO for 24 hours, in presence of ascorbic acid, Trolox (water-soluble α-tocopherol analog), β-carotene, retinol, riboflavin, thiamin, folic acid, niacin, pyridoxine, zinc, iron, manganese, and selenium. Fluorescence was measured at the wavelength pair of 370 and 440 nm as an index of the formation of AGEs and spectra were recorded for promising interactions at λex = 280 nm and λex = 370 nm. Within four standard antiglycating agents, aminoguanidine showed highest inhibitory response for BSA glycation followed by quercetin, gallic acid, and tannic acid. Promising antiglycation potential was seen for Trolox, riboflavin, Zn, and Mn as evidenced by decrease in the formation of AGEs and protein carbonyls.     

In Vitro Fungicidal Photodynamic Effect of Hypericin on Trichophyton spp

Hypericin is a natural photosensitizer used in photodynamic therapy (PDT), which has shown in vitro antifungal effect against Candida spp. The aim of this study was to evaluate the in vitro fungicidal effect of hypericin-PDT on dermatophytes. Trichophyton rubrum and Trichophyton mentagrophytes strains were incubated with different concentrations of hypericin for different times and exposed to light-emitting diode lamp (602 ± 10 nm, 10.3 mW cm^?2, and fluence 37 J cm^?2). Using the optimal incubation time, 60 min, a 3-log fungicidal effect was achieved with hypericin concentration ranges of 10–20 μM for T. rubrum and 20–50 μM for T. mentagrophytes (p = 0.95). Confocal fluorescence microscopy showed the localization of hypericin inside the dermatophytes diffusely distributed in the cytoplasm of conidia and hyphae and outside the nucleus. In conclusion, hypericin-PDT has a fungicidal effect in vitro on dermatophytes. Hypericin seems to be a promising photosensitizer to treat localized dermatophytic infections such as tinea pedis and onychomycosis.     

The Effect of Magnesium on Oxidative Neuronal Injury In Vitro

Abstract: The effect of magnesium on the oxidative neuronal injury induced by hemoglobin was assessed in murine cortical cell cultures. Exposure to 5 µ M hemoglobin in physiologic (1 m M ) magnesium for 26 h resulted in the death of about one-half the neurons and a sixfold increase in malondialdehyde production; glia were not injured. Increasing medium magnesium to 3 m M reduced neuronal death by about one-half and malondialdehyde production by about two-thirds; neuronal death and lipid peroxidation were approximately doubled in 0.3 m M magnesium. Comparable results were observed in spinal cord cultures. The NMDA antagonist MK-801 weakly attenuated hemoglobin neurotoxicity in low-magnesium medium, but tended to potentiate injury in physiologic magnesium. Incubation in low-magnesium medium alone for 24 h reduced cellular glutathione by ∼50% in mixed neuronal and glial cultures but by only 10% in pure glial cultures. The iron-dependent oxidation of phosphatidylethanolamine liposomes was attenuated in a concentration-dependent fashion by 2.5–10 m M magnesium; a similar effect was provided by 0.01–0.1 m M cobalt. However, oxidation was weakly enhanced by 0.5–1 m M magnesium. These results suggest that the vulnerability of neurons to iron-dependent oxidative injury is an inverse function of the extracellular magnesium concentration. At high concentrations, magnesium inhibits lipid peroxidation directly, perhaps by competing with iron for phospholipid binding sites. At low concentrations, enhancement of cell death may be due to the combined effect of increased NMDA receptor activity, glutathione depletion, and direct potentiation of lipid peroxidation.     

Effect of In Vitro and In Vivo Anakinra on Cytokines Production in Schnitzler Syndrome

IL-1 receptor antagonist anakinra is usually highly efficient in Schnitzler syndrome (SS), a rare inflammatory condition associating urticaria, fever, and IgM monoclonal gammopathy. In this study, we aimed to assess lipopolysaccharide (LPS)-induced production of inflammatory cytokines by peripheral blood mononuclear cells (PBMCs) before and after 1 month of anakinra in patients with SS. LPS-induced production of IL-1β, IL-6 and TNFα was assessed by enzyme-linked immunosorbent assay with and without anakinra in vitro, and before and after 1 month (in vivo condition) of treatment in 2 patients with SS. Spontaneous production of IL-1β, IL-6 and TNF-α by PBMCs was similar in the patients and the healthy controls and was almost undetectable. Stimulation with LPS caused a higher release of cytokines from the patients than from the healthy controls. Before in vivo anakinra start, in vitro adjunction of anakinra reduced the high LPS-induced production of IL-1β and TNFα in both patients and of IL-6 in one patient. After 1 month of treatment with anakinra, while the patients had dramatically improved, there was also a marked reduction in LPS-induced cytokines production, which was almost normalized in one patient. This study shows an abnormal LPS-induced inflammatory cytokines production in SS, which can be decreased or even normalized by in vitro and in vivo anakinra.     

Effect of Different Media on In Vitro Studies of Antibiotic Combinations

In an effort to determine the adequacy of a standard broth medium in the evaluation of antibiotic combinations, 20 strains of various bacterial species were studied simultaneously in Mueller-Hinton broth and in freshly drawn human serum from apparently healthy volunteers. Studies of growth dynamics by use of the usual plate dilution technique for quantitating colony-forming units were performed with strains of Staphylococcus aureus (methicillin-resistant and methicillin-susceptible), Streptococcus faecalis, Escherichia coli, Aerobacter, Klebsiella, and Proteus mirabilis. A variety of different antibiotics were investigated. With 19 of the 20 strains, interpretations of synergism or antagonism were the same in both media. Therefore, despite minor variations when the same strain was studied in both serum and broth, it is concluded that Mueller-Hinton broth is an adequate medium for use in studies of chemotherapeutic combinations in vitro. A simplified method for studying bactericidal activity is described, which is deemed practical for clinical microbiology laboratories and which led to the same conclusions regarding the combinations as were obtained by the more arduous plate dilution test.     

柴胡提取物对小鼠的体外免疫效应

利用淋巴细胞转化实验 ,肿瘤坏死因子α和白细胞介素 2的诱生和活性检测的方法 ,观察南、北柴胡提取物在体外对正常小鼠的免疫功能影响。结果显示 :1.北柴胡BuOH H2 O水溶物、北柴胡 5 0 %Eton提取后药渣组分、北柴胡 5 0 %Eton提取物以及南柴胡水提物能增强淋巴细胞转化作用 ;2 .不同柴胡提取物对IL 2的产生均有显著增强作用 ;3.北柴胡BuOH H2 O水溶物、北柴胡 5 0 %Eton提取物以及南柴胡水提物能显著增强TNFα的产生。本实验表明 ,南、北柴胡提取物能增强机体的细胞免疫功能 ,但南、北柴胡不同提取物的免疫作用有差异。     

Effect of Sodium Taurocholate on the In Vitro Growth of Lactobacilli

Abstract The effect on growth of a conjugated bile salt (sodium taurocholate) at physiological concentration was determined using cultures of Lactobacillus strains of murine origin. The bile salt stimulated the growth of one strain, did not affect the growth of another, but inhibited the growth of strains that produced relatively large amounts of the enzyme bile salt hydrolase. Comparison of the growth of isogenic strains that differed in the ability to produce bile salt hydrolase demonstrated that inhibition of growth was due to the accumulation of cholic acid in the culture medium as a result of the enzyme activity. Received: 15 January 1996; Revised: 26 March 1996; Accepted: 29 March 1996     

Effect of Paternal Age on Reproductive Outcomes of In Vitro Fertilization

Although the adverse effects of maternal aging on reproductive outcomes have been investigated widely, there is no consensus on the impact of paternal age. Therefore, we investigated the effect of paternal age on reproductive outcomes in a retrospective analysis of 9,991 in vitro fertilization (IVF) cycles performed at the Reproductive Medicine Center of the Third Affiliated Hospital of Guangzhou Medical University (China) between January 2007 and October 2013. Samples were grouped according to maternal age [<30 (3,327 cycles), 30–34 (4,587 cycles), and 35–38 (2,077 cycles)] and then subgrouped according to paternal age (<30, 30–32, 33–35, 36–38, 39–41, and ≥42). The groups did not differ in terms of fertilization rate, numbers of viable and high-quality embryos and miscarriage rate when controlling maternal age (P >0.05). Chi-squared analysis revealed that there were no differences in implantation and pregnancy rates among the different paternal age groups when maternal age was <30 and 35–38 years (P >0.05). However, implantation and pregnancy rates decreased with paternal age in the 31–34 y maternal age group (P <0.05). Our study indicates that paternal age has no impact on fertilization rate, embryo quality at the cleavage stage and miscarriage rate. For the 30–34 y maternal age group, the implantation rate decreased with increased paternal age, with the pregnancy rate in this group being significantly higher in the paternal <30 y and 30–32 y age groups, compared with those in the 36–38 y and 39–41 y groups.     

The Effect of Nisin and Monensin on Ruminal Fermentations In Vitro

When mixed ruminal bacteria and alfalfa were incubated in vitro, monensin and nisin both inhibited methane production so long as the concentrations were greater than 1 μM. Monensin- and nisin-dependent methane depressions caused a decrease in the acetate to propionate ratio (4.5 to 3.0). Total volatile fatty acid production was decreased by both monensin and nisin addition at concentrations greater than 2 μM. Starch-digesting ruminal bacteria were initially inhibited by monensin and nisin, but this effect disappeared after two to four transfers. Nisin always inhibited cellulolytic bacteria, but the nisin-dependent inhibition of cellulose digestion was no greater than the inhibition caused by monensin. Monensin and nisin also inhibited amino acid degradation, and nisin was more effective than monensin in controlling the growth of Clostridium aminophilum, an obligate amino acid-fermenting ruminal bacterium that can tolerate low concentrations of monensin. Because nisin was as potent as monensin, bacteriocins such as nisin may have potential as feed additives. Received: 2 December 1996 / Accepted: 10 February 1997     

Effect of Pituitary and Ovarian Hormones on Human Melanocytes In Vitro

Normal human melanocytes in culture became enlarged and dendritic after a 2-day incubation with either the pituitary (β-MSH, a potent analog of α-MSH, ACTH, FSH and LH) or the ovarian (estradiol, estriol and progesterone) hormones. Under the same experimental conditions, pituitary hormones also increased both the tyrosinase activity and tyrosinase-related protein-1 (TRP-1) while ovarian hormones increased TRP-1 but not tyrosinase activity. The results suggest that pituitary and ovarian hormones possibly induce hyperpigmentation of the skin by stimulating the melanogenesis in epidermal melanocytes, and that estradiol and progesterone may be involved in the pathogenesis of melasma (chloasma) usually developing between early adulthood and menopause in which a high concentration of serum ovarian hormones was maintained.     

Effect of Inoculum Size on In Vitro Susceptibility Testing with Lincomycin

There is disagreement in the literature as to whether lincomycin is primarily a bacteriostatic or a bactericidal agent against gram-positive cocci and also regarding the levels of activity of this agent against susceptible microorganisms. These questions were examined in a study of the effect of inoculum size on the results of tube dilution susceptibility determinations with lincomycin against 49 clinical isolates of Staphylococcus aureus and 25 strains of streptococci and pneumococci. Lincomycin was both highly active and bactericidal when tested against 40 strains of S. aureus with inocula containing a maximum of 10(4) cells per ml [median minimal inhibitory concentration (MIC), 0.78 mug/ml; median minimal bactericidal concentration (MBC), 1.56 mug/ml]. With inocula of 10(5) cells per ml, lincomycin was primarily bacteriostatic (median MIC, 1.56 mug/ml; median MBC, 12.5 mug/ml). There were further decreases in inhibitory levels and significant losses of bactericidal activity when inocula containing more than 10(7) cells were tested (median MIC, 3.13 mug/ml; median MBC > 100 mug/ml). Similar measurements with streptococci and pneumococci revealed a lesser effect of inoculum size. The mean MBC value for alpha-hemolytic streptococci increased from 0.40 to 1.05 mug/ml with an increase in inocula from 10(4) to 10(6) cells per ml, but without a marked increase in MIC values. Similar results were obtained for beta-hemolytic streptococci and pneumococci.