Reduction of GABA-mediated inhibitory postsynaptic potentials in hippocampal CA1 pyramidal neurons following oral flurazepam administration

Oral administration of the benzodiazepine, flurazepam, for one week results in tolerance in vivo and in vitro and in a reduction in recurrent and feedforward inhibition in vitro in the CA1 pyramidal cell region of hippocampus. In the present study CA1 pyramidal cells were examined intracellularly in vitro in rat hippocampal slices (500 microns) from rats sacrificed two or seven days after cessation of oral flurazepam treatment. Following drug treatment, the membrane characteristics of CA1 pyramidal cells were not significantly different from control neurons. GABAA-mediated, early inhibitory postsynaptic potentials were significantly reduced in amplitude (60%) in pyramidal neurons from rats killed two days, but not in those killed seven days, after the end of drug administration. The decrease in early inhibitory postsynaptic potential amplitude was observed using just-subthreshold, threshold and supramaximal orthodromic stimulation as well as following antidromic activation. The magnitude of the decrease in the early inhibitory postsynaptic potential amplitude was similar in the presence of the GABAB antagonist, CGP 35348, and could not be attributed to differences in the strength of afferent stimulation between flurazepam-treated and control groups. The size of the GABAB-mediated, late inhibitory postsynaptic potentials was also significantly decreased (45%) in comparison to control cells. Reversal potentials for both the early (-72 mV) and late (-92 mV) hyperpolarizations were not significantly different between groups. Following high intensity orthodromic stimulation, in the presence of an intracellular sodium channel blocker (QX-314) which also blocks the GABAB-mediated late hyperpolarization, a bicuculline-sensitive late depolarizing potential was unmasked in neurons from FZP-treated rats, but never from control cells. Excitatory postsynaptic potential amplitude was significantly increased in flurazepam-treated neurons and the threshold for the synaptically-evoked action potential was significantly increased. Following depolarizing current injection, the duration and frequency of pyramidal cell discharges and the action potential threshold were not altered by oral flurazepam treatment. The amplitude of the fast afterhyperpolarization was also not changed. Overall, the findings indicate an impairment of transmission at GABAergic synapses onto hippocampal CA1 pyramidal cell neurons after chronic benzodiazepine treatment at a time when rats are tolerant to the anticonvulsant effects of the benzodiazepines in vivo.

[Experimental comparison of the analgesic action of Aconitum and its processed products]

This paper deals with the effects of crude Aconitum and Aconitum processed by a new method of moistening and steaming, and by method of pharmacopoeial stipulation on the analgesic action with writhing test and hot plate test in mice. The result shows that the Aconitum processed by new method No 1, which applies moistening in water for 48h and then heating with high pressure steam (68.65kPa, 115 degrees C) for 2h has an advantage over that processed according to pharmacopoeial routine (P < 0.05).

Impairment of feedforward inhibition in CA1 region of hippocampus after chronic benzodiazepine treatment

The strength of feedforward inhibition was assessed in the CA1 region of in vitro hippocampus of benzodiazepine tolerant rats 2 and 7 days after 1 week oral flurazepam (FZP) administration. Feedforward inhibition was activated with a Schaffer collateral stimulation just-subthreshold for a population spike followed at intervals of 10-100 ms by test population spikes elicited from the subicular side of the recording electrode. The amplitude of test spike was reduced to a lesser degree 2 days, but not 7 days, after FZP treatment, suggesting a decrease feedforward inhibition in treated rats coinciding with the time course for reversal of anticonvulsant tolerance in vivo.

The recombination signal sequence-binding protein RBP-2N functions as a transcriptional repressor

We have identified a cellular protein, RBP-2N, a presumed recombinase, as a repressor of transcription. Inhibition of transcription by RBP-2N was dependent on its DNA recognition site and was demonstrated in vitro and in vivo. This repression appears to be general, as transcription mediated by SP1 and Gal4/VP16 was inhibited by RBP-2N. The protein was purified to near homogeneity from human cells on the basis of its binding to a site present in the promoter of the adenovirus pIX gene. The DNA recognition sequence is 5'-TGGGAAAGAA, which is markedly different from the recombination signal sequence originally identified as the target site for this protein. The sequence of the purified protein is 97% identical with that published for the mouse RBP-2N protein. The reported homolog in Drosophila is Suppressor of Hairless. RBP-2N binding sites are present in a number of cellular and viral promoters, so RBP-2N may have a general role in transcriptional repression.

[Spiral shaped bacteria in the human gastric biopsy]

Biopsy specimens from the gastric mucosa of 149 patients who underwent gastroduodenal endoscopy for upper gastrointestinal complaints were studied by light microscopy and culture. Spiral shaped bacteria were detected in four of the specimens by smears with Gram stain. The positive rate was 2.68%, but these bacteria and HP did not grow in culture. The characteristic helical morphology of the bacteria appears to be similar to that of the bacteria found in the stomach of cats and dogs. And what of significance in these cases is the presence of spiral shaped bacteria in association with chronic gastritis.

Far-field distribution of double-heterostructure diode laser beams

Previous analytical solutions for the far-field of a double-heterostructure diode laser have been restricted in scope because of several ad hoc assumptions, which were incorporated at rather early stages of the analysis. Based on a rigorous solution of the Helmholtz equation, it is shown that the commonly used assumption of separability of the field distributions along the two transverse axes of a diode may be misleading under certain conditions. Furthermore, the theoretical upper limit on the F.W.H.M. divergence angle is shown to be 65.5°, which is more realistic than the previous estimate of this parameter.

GCR1, a transcriptional activator in Saccharomyces cerevisiae, complexes with RAP1 and can function without its DNA binding domain

In Saccharomyces cerevisiae, efficient expression of glycolytic and translational component genes requires two DNA binding proteins, RAP1 (which binds to UASRPG) and GCR1 (which binds to the CT box). We generated deletions in GCR1 to test the validity of several different models for GCR1 function. We report here that the C-terminal half of GCR1, which includes the domain required for DNA binding to the CT box in vitro, can be removed without affecting GCR1-dependent transcription of either the glycolytic gene ADH1 or the translational component genes TEF1 and TEF2. We have also identified an activation domain within a segment of the GCR1 protein (the N-terminal third) that is essential for in vivo function. RAP1 and GCR1 can be co-immunoprecipitated from whole cell extracts, suggesting that they form a complex in vivo. The data are most consistent with a model in which GCR1 is attracted to DNA through contact with RAP1.

Role of cysteines in the activation and inactivation of brewers' yeast pyruvate decarboxylase investigated with a PDC1-PDC6 fusion protein

Possible roles of the Cys side chains in the activation and inactivation mechanisms of brewers' yeast pyruvate decarboxylase were investigated by comparing the behavior of the tetrameric enzyme pdc1 containing four cysteines/subunit (positions 69, 152, 221, and 222) with that of a fusion enzyme (pdc1-6, a result of spontaneous gene fusion between PDC1 and PDC6 genes) that is 84% identical in sequence with pdc1 and has only Cys221 (the other three Cys being replaced by aliphatic side chains). The two forms of the enzyme are rather similar so far as steady-state kinetic parameters and substrate activation are considered, as tested for activation by the substrate surrogate pyruvamide. Therefore, if a cysteine is responsible for substrate activation, it must be Cys221. The inactivation of the two enzymes was tested with several inhibitors. Methylmethanethiol sulfonate, a broad spectrum sulfhydryl reagent, could substantially inactivate both enzymes, but was slightly less effective toward the fusion enzyme. (p-Nitrobenzoyl)formic acid is an excellent alternate substrate, whose decarboxylation product p-nitrobenzaldehyde inhibited both enzymes possibly at a Cys221, the only one still present in the fusion enzyme. Exposure of the fusion enzyme, just as of pdc1, to (E)-2-oxo-4-phenyl-3-butenoic acid type inhibitors/alternate substrates enabled detection of the enzyme-bound enamine intermediate at 440 nm. However, unlike pdc1, the fusion enzyme was not irreversibly inactivated by these substrates. These substrates are now known to cause inactivation of pdc1 with concomitant modification of one Cys of the four [Zeng, X.; Chung, A.; Haran, M.; Jordan, F. (1991) J. Am. Chem. Soc. 113, 5842-49].(ABSTRACT TRUNCATED AT 250 WORDS)

[Antisteatotic effects of four kinds of dietary fibers in rats fed on high cholesterol diet: a preliminary morphometric analysis]

The hypolipidaemic and antisteatotic effects of the Konnyaku Powder (KP) have been reported before. In order to evaluate further the antisteatotic role played by KP, the effects of KP on the levels of liver lipid and on the hepatic histopathology and morphometry in comparison with those of pectin, algin and agar were studied. Sixty Wistar strain rats were divided into 6 groups: a normal diet group, a high cholesterol diet group (HC), and 4 test groups, in which the animals were fed on a diet similar to that of the high cholesterol diet group with addition of KP, pectin, algin or agar at a dosage of 5%, respectively. All the animals were killed at the end of the diet treatment for 9 weeks. The results showed that relative liver weights were lower in four experimental groups than in the HC group. The levels of total and free cholesterol, and triglyceride in the liver were lower in KP group than in HC group and in the other three experimental groups. Hepatic histopathology and morphometric examination indicated that antisteatotic effects of KP appeared to be much more significant than those of the other fibers.

[Observation of T cells and T-cell subsets in mycosis fungoides]

Skin lesions from 14 patients with mycosis fungoides (MF) were studied immunohistochemically with monoclonal antibodies that identify pan T (Leu4), T-helper/inducer (TH), T-suppressor/cytotoxic (Ts) (Leu3a, Leu2a) and pan B (Leu12) cells. Lymphoid cell reactivity was diverse among these cases. Among 12 cases of MF, TH cells were predominant over Ts cells, and one case featured nonreactive Ts cells in the dermis. In one case of MF, Ts cells were predominant. One case of MF showed strong reactivity for both T cell subset markers. The intraepidermal lymphoid cellularity was Leu4-reactive in 14 cases of MF. Among these 14 cases, the intraepidermal cellularity was Leu3a-reactive in 11 and Leu2a-reactive in 4. The use of such studies of T cell subsets may demonstrate a correlation of MF with cytomorphology, clinical stage, and disease prognosis.

Regulation of 5-Aminolevulinic Acid Synthesis in Developing Chloroplasts : IV. An Endogenous Inhibitor from the Thylakoid Membranes

5-Aminolevulinic acid synthesis in isolated, intact, developing chloroplasts from greening cucumber (Cucumis sativus) cotyledons was inhibited by broken chloroplast fragments. It was shown that the inhibitory constituent was associated with the thylakoid membrane system. The inhibitor was resistant to boiling, was not a form of ribonuclease, and did not inhibit Mg-chelatase, indicating that massive organelle destruction was not involved. The inhibitor was also found in etioplast and mature chloroplasts; and it was found in barley as well as cucumber. 5-Aminolevulinate synthesis in the dark with exogenous ATP and NADPH, or in the light without added cofactors, were inhibited approximately equally. In the dark, 5-aminolevulinate synthesis and protochlorophyllide synthesis from glutamate were inhibited to about equal extent. The inhibition was decreased when the membranes were washed with aqueous acetone prior to incubation. The inhibition by the unknown factor was compared to the inhibition by gabaculine, 4-amino-5-hexynoic acid, protoheme, and glutathione. The unknown inhibitor appeared to have a number of similarities with protoheme.

[Prophylactic effect of refined amorphophallus konjac on MNNG-induced lung cancers in mice]

Three hundred and seventy LACA mice of seven weeks old were used in 2 batches for studying the prophylactic effect of Konjaku powder on MNNG-induced lung cancers. These mice (within each batch) were randomly allocated to four groups, namely positive control (MNNG), refined Amorphophallus Konjac (R.A.K.), complex (MNNG + R.A.K.), and blank control (C). In MNNG group, MNNG (250 micrograms) was injected intravenously once five days for seven times in each mouse, the total dosage of MNNG was 1.75 mg. In R.A.K. group, according to w/w, 8% R.A.K. was well mixed into 92% common diet for long-term term breeding. In complex group, MNNG was given as that in MNNG group and the mice were reared as those in R.A.K. group. The mice in MNNG group and in C group were all reared by common diet. The results of experiments showed different degrees of preventive effect of R.A.K. on MNNG-induced lung cancers in LACA mice. R.A.K. not only exerted effect on the number of induced cancer, causing a drop of the cancerous rate from 79.75% to 20.00% and the mean number of cancer in each animal, but also prolonged the survival time of animals. At the same time, the constituent ratio of the kinds of tumor denoted a decrease in malignancy (adenoma with malignant change), an absence of adenocarcinoma and relative increase in benign adenoma. The results of experiments also exhibited good duplication as well as absence of adverse reactions to Konjaku powder.

[Small-airway lesions induced by inhalation of asbestos dust in dogs--pathological and aetiological studies]

This paper presents the pathological changes of the small airways of dogs inhaling asbestos dust in the workshop of Xin Kong Asbestos Mine for 1 to 3 years. Dogs of the experimental group showed that variable degrees of dust deposition and fibrous tissue reaction were found in all the three types of the small airways-respiratory bronchioles, alveolar ducts and membranous bronchioles of both lungs. The lesions in the lung increased with the duration of exposure. These changes in the canine small airways resulting from asbestos dust were very much similar to those of the humans. In addition, deposited dust collected from the workshop of the asbestos mine, and 50 dust particles selected randomly in foci were identified in situ by energy dispersive X-ray analysis. Findings demonstrated that the majority of the dust particles in the foci was principally mixed silicate dust. Among them asbestos dust predominated absolutely, and there were more amphiboles than chrysotiles. Therefore, it is concluded that the small airway lesions induced in the dogs are mainly due to mixed asbestos dust, and that there appears to exist a dose-response relationship.

[Chemical constituents of Osbeckia chinensis L]

Five constituents, 2-furoic acid, succinic acid, ursolic acid, quercetin and daucosterol were isolated and identified from Osbeckia chinensis. All of them are reported to have been found from this plant for the first time.