Haloperidol treatment at pre-exposure phase reduces the disturbance of latent inhibition in rats with neonatal ventral hippocampus lesions

Animals with neonatal ventral hippocampal lesions develop during or after adolescence abnormal behaviors related to schizophrenia such as anxiety and latent inhibition disruption. The aim of this study was to test whether haloperidol injection prior to pre-exposure session in the latent inhibition test would facilitate latent inhibition.     

A new screening method for investigating microbial interactions

Interactions among Candida albicans, Staphylococcus aureus and Escherichia coli were investigated using a screening system in which test micro-organisms were incorporated in agar discs and effector micro-organisms in fluid growth media. Total as well as partial inhibition of test micro-organisms was observed in agar discs when these were incubated in broths containing effector micro-organisms. The ratio of numbers of test to effector micro-organisms was found to be of importance in the inhibition effect. The technique was found to be cheap, simple and versatile.     

Migration inhibition test with thyroid membrane antigen in Graves-Basedow disease and nodular goiter]

The evaluation of the migration inhibition test with thyroid membrane antigen was carried out in 20 patients with Graves' disease, 13 patients with neutral nodular goiter and 13 healthy subjects. A significant inhibition of migration by thyroid antigen as compared to the control group was demonstrated only in the patients with Graves' disease (the value of the migration index was 0.57 +/- 0.07). The respective value was 0.79 +/- 0.16 in patients with nodular goiter and 0.85 +/- 0.11 in healthy subjects. The results obtained indicate the practical value of the migration inhibition test in diagnosing the thyroid diseases having an autoimmune background.     

Development of ecotoxicity assay based on inhibition of respiring activity in microbial community using XTT reduction

The aim of this study is to develop ecotoxicity assay for evaluating the influence of chemicals on a microbial ecosystem based on XTT reduction inhibition (XTT assay). XTT reduction method is used for quantification of the microbial respiratory activity. Since the XTT assay indicates the inhibition of microbial respiratory activity, it could evaluate the toxicity of chemicals. Suitable conditions for the XTT assay were determined to be 200 mg/L of particulate organic carbon as test microbe concentration and 15 min of assay time using activated sludge. Toxicities of several chemicals evaluated by activated sludge as test microbes were examined under these conditions. Sensitivity for the toxicity evaluated by the XTT assay using activated sludge microbes was almost the same value was that for the OECD activated sludge respiration inhibition test (ASRI test). XTT assay was also applied for evaluating the influence of chemicals on the soil microbial community and the XTT assay was used to evaluate a median effective concentration (EC(50)) value of 3,5-dichlorophenol (3,5-DCP). The EC(50) value of 3,5-DCP was almost the same as the value using activated sludge as test microbes. These results suggest that the XTT assay using both mixed cultures of non-contaminated environments and chemical extracts from various contaminated environments could evaluate the influence on microbial ecosystems affected by toxic chemicals.     

Blocking and unblocking of cell-mediated anti-tumor immunity in mice, as detected by the leucocyte adherence inhibition test

Further observations have been made using the in vitro leucocyte adherence inhibition (LAI) test previously described. The test has been slightly modified and shown to give highly reproducible results in detecting cell-mediated immunity in peritoneal cells of mice exposed to tumors, and in demonstrating factors which modify this immunity.Two different methylcholanthrene-induced tumors stimulated specific reactivity in their hosts as shown by the leucocyte adherence inhibition test employing soluble tumor extracts as antigens. When serum from tumor-bearing mice was added to the mixture, reactivity was specifically blocked. Serum from mice after tumor removal lacked the ability to block the leucocyte adherence inhibition reaction, but specifically reversed the effect of blocking serum (unblocking).Thus three important phenomena of tumor immunity, previously discovered by tedious and complex techniques, are now detectable by a brief, simple procedure.     

Relation between bacterial strain resistance to solvents and biodesulfurization activity in organic medium

Microorganisms used in biodesulfurization of petroleum products have to withstand high concentrations of hydrocarbons. The capacities of seven desulfurizing strains of Rhodococcus to be active in the presence of solvents were evaluated. Octanol and toluene (log P=2.9) were selected as toxic solvents. The effect of the solvents was determined by measuring either inhibition of growth or the decrease in respiratory activity of the cells. Differences among strains in their resistance to solvent responses were observed, but these variations were dependent on the test used. Resistance to solvents was then compared to the capacity of the different strains to retain biodesulfurization activity in the presence of hexadecane. Inhibition of desulfurization by high concentrations of hexadecane was found to be well correlated to the sensitivity of the strains to respiration inhibition by toluene, but not to growth inhibition. This result also showed that the respirometric test was a rapid and reliable test to select solvent-resistant strains for use as resting cells in biocatalysis processes, such as biodesulfurization, in organic media.     

An evaluation of the peripheral leukocyte migration inhibition test as a correlate of delayed cutaneous hypersensitivity.

The leukocyte migration inhibition test was used to study the in vitro response to PPD of peripheral blood leukocytes from six Mantoux-positive and five Mantoux-negative volunteers. All tests were performed using both micro and macro versions of the test. Results with the two techniques were usually, but not always similar. Subjects were tested weekly for 6 weeks and variation in the degree of inhibition was noted from week to week. Leukocytes from Mantoux-positive subjects sometimes did not have significant migration inhibition while those from Mantoux-negative subjects sometimes did. Despite this variation the Mantoux-positive subjects both as a group and in most cases individually, had significantly greater mean migration inhibition than the Mantoux-negative subjects. These results suggest that sequential testing rather than a single determination may provide a more meaningful index of cellular immunity.     

NMR determination of Electrophorus electricus acetylcholinesterase inhibition and reactivation by neutral oximes

Neurotoxic organophosphorus compounds (OPs), which are used as pesticides and chemical warfare agents lead to more than 700,000 intoxications worldwide every year. The main target of OPs is the inhibition of acetylcholinesterase (AChE), an enzyme necessary for the control of the neurotransmitter acetylcholine (ACh). The control of ACh function is performed by its hydrolysis with AChE, a process that can be completely interrupted by inhibition of the enzyme by phosphylation with OPs. Compounds used for reactivation of the phosphylated AChE are cationic oximes, which usually possess low membrane and hematoencephalic barrier permeation. Neutral oximes possess a better capacity for hematoencephalic barrier permeation.NMR spectroscopy is a very confident method for monitoring the inhibition and reactivation of enzymes, different from the Ellman test, which is the common method for evaluation of inhibition and reactivation of AChE. In this work ¹H NMR was used to test the effect of neutral oximes on inhibition of AChE and reactivation of AChE inhibited with ethyl-paraoxon. The results confirmed that NMR is a very efficient method for monitoring the action of AChE, showing that neutral oximes, which display a significant AChE inhibition activity, are potential drugs for Alzheimer disease. The NMR method showed that a neutral oxime, previously indicated by the Ellman test as better in vitro reactivator of AChE inhibited with paraoxon than pralidoxime (2-PAM), was much less efficient than 2-PAM, confirming that NMR is a better method than the Ellman test.     

The Use of the Mercury Inhibition Test in the Recognition of Virulent Strains of Staphylococci in a Hospital Environment

The effect of mercury salts on 200 hospital strains of Staph. pyogenes was investigated. Two methods of performing the mercury inhibition test were compared, and the agar plate technique was found to be the more practical. An attempt was made to correlate the results of the test with antibiotic sensitivity tests, phage patterns and virulence tests. Resistance to mercury was found to be associated with antibiotic resistance, and the majority of the resistant strains were found in the lytic group III. No difference in virulence between mercury-resistant and mercury-sensitive strains could be demonstrated by intracerebral inoculation of mice. The mercury inhibition test may be useful as a screening test for “hospital staphylococci”.     

1株产细菌素乳酸菌的筛选和鉴定

目的 从植物性材料中筛选产细菌素的乳酸菌。方法 琼脂扩散法。结果 所筛选的产细菌素R260菌株经鉴定为植物乳杆菌。排除有机酸、过氧化氢等干扰因素后,发酵液仍有很强的抑菌作用;用胰蛋白酶和胃蛋白酶处理后,发酵液抑菌活性急剧下降,因而确定产生的抑菌物质具有蛋白质性质,是一种细菌素。抑菌谱试验测定表明,此菌株的发酵液不仅抑制革兰阳性菌,而且对部分革兰阴性菌也有抑制作用,因此产生的是一类广谱细菌素。结论筛选到了1株产广谱细菌素的乳酸菌。     

The effect of DOPA on the reciprocal inhibition of the innervation centers of antagonistic muscles in newborn rat pups]

In experiments on 5--7- and 16-day rat puppies with acute lesion of the spinal cord, by means of monosynaptic tests, studies have been made of the effect of DOPA on reciprocal inhibition of antagonist muscles. Test stimuli were applied to n. tibialis, conditioned ones--to n. peroneus. It was shown that the pattern of the effects depends on the action of the drug on the magnitude of the initial monosynaptic reflex used as a test. It the latter was initially inhibited, the conditioned stimulation resulted within the first 1-8 msec not in the development of postsynaptic inhibition, but in evident facilitation, which was longer in 5--7-day animals. The level of presynaptic inhibition was somewhat lower than the initial one, but exhibited longer duration. In case of facilitation of a control test after DOPA injection, configuration of reciprocal inhibition curves did not significantly differ from that obtained before administration of the drug.     

Effects of membrane potential on mechanical activation in skeletal muscle

The effect of subthreshold depolarization on mechanical threshold was investigated in tetrodotoxin-poisoned mammalian and amphibian skeletal muscle fibers using a two-microelectrode voltage-clamp technique. Mechanical threshold was determined with a 2-ms test pulse. The immediate effect of depolarization was inhibition of the mechanical system. The consequent increase in the test pulse threshold was linearly related to the size of the depolarization and there was, on the average, a 10% increase in threshold for a 10-mV depolarization in mammalian fibers. The duration of the inhibitory period was also related to the size of the depolarization. Inhibition was interrupted by the onset of activation (seen as a reduction in the test pulse threshold), and in rat soleus fibers this occurred within 100 ms with a 20-mV depolarization, inhibition decayed within 10 ms. The decay of activation after brief conditioning pulses was initially rapid (on the average, the test pulse threshold recovered to 80% of its control value within 1 ms) and then slow (full recovery took 100-500 ms). After long conditioning pulses, activation often decayed into a period of inhibition. When depolarization (of 20 mV or more) was maintained for several seconds, the fibers became inactivated. Rat extensor digitorum longus and sternomastoid fibers were strongly inactivated by depolarization to -40 mV and the test pulse to +40 mV did not cause contraction.     

Characteristics of the NK cells in Syrian hamsters carrying tumors with varying metastatic and resistance-suppressing activity

Experiments in vivo and in vitro were made to study the effects of HETR-MLN-8 and HETR tumor cells differing in metastatic ability and inhibition of the natural host resistance to tumor on cytotoxic activity of NK from Syrian hamsters. Marked inhibition of cytotoxicity and ability for interferon activation was detected in NK isolated from tumors (as compared with blood), with that inhibition being far more pronounced in highly malignant HETR-MLN-8 tumors. This may indicate a direct inhibitory action of the tumor or its products on NK cytotoxicity. The in-vitro competition inhibition test yielded results showing that HETR-MLN-8 cells capable of in-vivo inhibition of the natural host resistance to the tumor also display much more demonstrable ability for in-vitro inhibition of NK cytotoxicity as compared to HETR cells.     

大肠埃希菌对化疗药物顺铂体外敏感性的探讨

目的通过体外细菌敏感性试验研究细胞周期非特异性化疗药物顺铂（Cisplatin,DDP）对条件性致病菌———大肠埃希菌的抑菌活性。方法分别用滤纸片法和96孔板法对顺铂的抑菌活性进行研究。其中,滤纸片法是以庆大霉素作为阳性对照,以生理盐水作为阴性对照,用直尺测不同浓度顺铂抑菌圈直径大小;96孔板法是用酶标仪测定吸光值,然后计算抑菌率。根据不同浓度大肠埃希菌的抑菌率曲线,利用origin 75拟合标准曲线做图并计算出能使50%大肠埃希菌死亡所需的顺铂使用剂量（IC50）。结果滤纸片法检测结果发现,5、2.5、1.25、0.625、0.313和0.156 mg/mL的顺铂对大肠埃希菌的抑菌圈大小分别为14、121、19、.678、.33和0 mm,而阳性对照6 670 IU/mL庆大霉素的抑菌圈大小为18 mm。96孔板法检测结果发现,顺铂对大肠埃希菌的抑制率均随用药剂量的增加而增大,呈＂S＂型曲线。用药后6、24、48和72 h时顺铂的IC50值分别为30.29、42.56、80.24和98.69μg/mL。结论顺铂对大肠埃希菌有抑制生长的作用;其抑菌作用随顺铂用药作用时间的延长而减弱。     

Rosette Inhibition Test in Severely Burned Patients

The rosette inhibition test has been advocated as a test of immune reactivity in patients given transplants. We have done the test in lymphocytes from patients with severe burns, non-burnt control patients, and normal subjects. There was no correlation with the period of immunosuppression which follows a severe burn, though both groups of patients showed a wider range of minimal inhibitory concentrations (M.I.C.) than the normal group. Wide day-to-day variation of M.I.C. in burn and control patients was noted; this seemed to correlate with the ratio of sodium to potassium excreted in the urine. In-vitro experiments suggest that the M.I.C. is correlated with a plasma constituent which may be similar in action to hydrocortisone and that the rosette inhibition test is not a direct measure of immune reactivity.     

Mutagenicity testing of dichloromethane in short-term mammalian test systems

Several short-term mammalian test systems were used for mutagenicity testing of the organic solvent dichloromethane. The compound was negative in the forward mutation test on the HGPRT locus in Chinese hamster cells and the unscheduled DNA synthesis test in both human and hamster cells. In the test on DNA synthesis inhibition, dichloromethane caused an aspecific inhibition in both human and hamster cells, but in this test the effect did not indicate a DNA-damaging action. A weak positive effect was found in the test on sister-chromatid exchanges in hamster cells.     

Mutagenic and cytotoxic activities of benfuracarb insecticide

Benfuracarb is a carbamate insecticide used to control insect pests in vegetables and it has anti-acetylcholinesterase activity lower than other carbamates. Cytotoxic effects of benfuracarb were evaluated by using root growth inhibition (EC₅₀), mitotic index (MI), and mitotic phase determinations on the root meristem cells of Allium cepa and mutagenic effects were determined in Salmonella typhymurium Ames test by TA98 and TA100 strains with and without metabolic activation. In Allium test, 1 % DMSO was used as negative control group and 10 ppm MMS was used as positive control group. 75 ppm concentration of benfuracarb was found as EC₅₀. In MI and mitotic phases determination study, 37.5, 75 and 150 ppm doses of benfuracarb were used. Dose-dependent cytotoxic activity was found by root growth inhibition and MI studies. It was identified that mitotic inhibition activity of benfuracarb was higher than 10 ppm MMS. In Ames test, mutagenic activity was not observed and over 200 µg/plate of benfuracarb was determined as cytotoxic to S. typhymurium strains. Benfuracarb can be called as “mitotic inhibitor” but not called as mutagen.     

Protein phosphatase inhibitory activity of tautomycin photoaffinity probes evaluated at femto-molar level

Herein we describe the further improvement of our in-house developed firefly bioluminescence assay system for the determination of inhibition of protein phosphatase (PP). The advantage with the new system is higher sensitivity as well as being time and sample efficient. The inhibition activity of tautomycin with PP1gamma was determined using the upgraded test system and Ki was found to be 4.5 nM, which compare favorably with the activity reported previously by others using different methods. The test system was then used in order to determine the activity of nine tautomycin (TTM) photoaffinity probes. One of the TTM photoaffinity probes (anti-10) was found to possess higher activity than the natural product itself with a Ki of 3.4 nM, while the remaining photoaffinity probes were found to possess Ki in the range of 8.0-213 nM.     

Use of the indirect hemagglutination inhibition reaction for evaluating the specific activity of allergens

To evaluate the specific activity of house-dust allergen, the passive hemagglutination inhibition test was used. Nine commercial batches of house-dust allergen were studied by means of this test. The results of the determination of the activity of house-dust allergen in the passive hemagglutination inhibition test, the skin tests and the indirect mast-cell degranulation test were in good correlation.     

Evaluation of Rosette Inhibition Test in Renal Transplantation

Serial rosette inhibition tests were performed on 11 renal transplant patients in an attempt to predict graft rejection. The rosette inhibition titre was higher in immunosuppressed patients than in normal subjects. The test was of predictive value in only two out of 12 rejection episodes, where a fall in titre to normal levels occurred 48 hours and 24 hours, respectively, before biochemical evidence of rejection. In two further rejection episodes the titre fell at the time of rejection. The titre changes in all tests were small and there were frequent inconsistencies in the results of individual tests. A study of the variables was undertaken, with standardization of the technique, and improvements were made in reading the test. Despite these changes the test was still not sufficiently accurate or reliable to be used as the basis of treatment of rejection episodes.