[Evaluation of the bacteriostasis and the acute hemolytic activity in vitro of three sorts of resinifying agent.]

The bacteriostatic test for the anaerobic which had a direct bearing on pulpal-periapical infection and oral common aerobic bacteriosia were performed.The results indicated the bacteriosia ability of three sorts of resinify agent is in sequence:FR109>FR>GR.We found that FR and GR had no acute hemolyzation in the hemolytic test in vitro,but RF109 caused hemolysis.

[A preliminary study of HCV infections with hemophilia and their family members]

28 cases of hemophilia were examined for HCV infection status by using the Kehua anti-HCV ELISA kit of second generation. It was found that the infection rate was 78.5% and the infection rate was even higher with patients who had received transfusions or preparations of coagulatory factors. 10 families of 15 patients were also investigated. It was found that of 15 hemophilia patients, 12 showed positive anti-HCV, while none of their 53 family members exhibited any positive anti-HCV. In 8 children of 9 couples no positive anti-HCV was found. Our results revealed that the hemophilia patient may get infected with HCV by receiving multiple transfusions or preparation of coagulatory factors. The risk of getting infected with HCV via daily-life contact including sexual contact is extremely low.

Chemical modification of aminopeptidase isolated from Pronase

Chemical modification of aminopeptidase from pronase has revealed two important histidines in enzyme catalysis. In the absence of metal ions, modification of the readily-modified histidine (pKa 6.9 +/- 0.5) results in a drastic loss of activity, indicating that this residue is indispensible for enzyme activity. In the presence of CaCl2, the modified enzyme still retains approx. 60% of the activity, whereas modification of another histidine (pKa 7.7 +/- 0.2) leads to a dramatic loss of activity. In fact, the enzyme with the first histidine being modified is active only in the presence of metal ions. Moreover, modification of the second histidine is prevented by the presence of Ca(II). These results indicate that the second histidine is serving as a ligand for Ca(II) and the bound Ca(II) is directly involved in enzyme catalysis. The c.d. spectra of the modified and unmodified enzymes in the absence or presence of CaCl2 are all very similar, indicating that no gross conformational changes in protein occur upon modification or by the presence of Ca(II). Modification of both histidines is prevented by the presence of a competitive inhibitor, suggesting that they are located in the active centre. Modification of 11 amino groups, two tyrosines, or four arginines causes no appreciable inactivation of the enzyme, indicating that these residues are not directly involved in enzyme catalysis.

Generality of the shared active site among yeast family site-specific recombinases. The R site-specific recombinase follows the Flp paradigm [corrected]

Mutations of the invariant Int family tetrad residues, the RHR triad, and the active site tyrosine, within the Zygosaccharomyces rouxii site-specific recombinase R cause the same "step-arrest" phenotypes as they do in the Flp recombinase of Saccharomyces cerevisiae. In "half-site" recombinations, the R recombinase exhibits catalytic complementation between an RHR triad mutant and an active site tyrosine mutant. Strand cutting by R follows the "trans" DNA cleavage rule. These results are best explained by the assembly of a functional active site from partial active sites harbored by the ARg monomers. Complementation tests using single and double step-arrest ARg mutants verify critical predictions of the "shared active site" model. A wild type monomer paired with an RHR triad-Tyr358 double mutant is a catalytically inactive combination. Pairwise combinations of a single or a double RHR mutant with R(Y358F) yield comparable levels of catalytic complementation. These results strongly imply conservation of the mechanism of active site assembly and the mode of substrate cleavage within the yeast family site-specific recombinases, and perhaps within the larger Int family recombinases [corrected].

Influence of muscle activity on the actions of chloride channel blockers in the mouse skeletal muscle

The purpose of this work was to investigate the effect of channel blockers in the presence and absence of nerve and/or muscle activity. 9-Anthracenecarboxylic acid (0.03 mM), a chloride channel blocker, increased both the amplitude and duration of the contractile response to direct stimulation in the mouse soleus muscle in either low Ca2+ Krebs (0.25 mM) or normal Ca2+ Krebs (2.5 mM) containing 0.1 mM 4-aminopyridine (potassium channel blocker). In addition, spontaneous contractions were induced by 9-anthracenecarboxylic acid in low Ca2+ Krebs. On the other hand, the combination of two potassium channel blockers, 4-aminopyridine (0.3 mM) plus tetraethylammonium ion (10 mM), increased the twitch amplitude but only slightly increased the contractile duration in the mouse soleus muscle in normal Krebs. The contraction-potentiating actions of 9-anthracenecarboxylic acid were inhibited by denervation, while those of 4-aminopyridine plus tetraethylammonium were not. Chronic exposure to the sciatic nerve to a lidocaine-cuff, but not to a colchicine-cuff, exhibited similar effects as denervation. Direct electrical stimulations were applied for 2 days to the soleus muscle through implanted teflon-coated multistranded electrodes in vivo, beginning immediately after denervation or cuff treatments. The contraction-potentiating effects of 4-aminopyridine plus 9-anthracenecarboxylic acid or 9-anthracenecarboxylic acid in low Ca2+ Krebs were restored in the denervated or lidocaine-cuff-treated soleus muscle by chronic direct stimulations. The membrane potential and input resistance of muscle fibres and the effects of 9-anthracenecarboxylic acid, which were altered by denervation or cuff treatment, were also partially restored by this measure. When sciatic nerves had been treated with lidocaine-cuff for 4 days and the cuff was then removed for 7 days, the contraction-potentiating effects of 9-anthracenecarboxylic acid were also restored. Four days after Achilles tenotomy, the contraction-potentiating effects of 9-anthracenecarboxylic acid were markedly inhibited. It was concluded that muscle activity controls the properties of chloride channels and that neural activity may affect the properties of chloride channels via enhancement of the muscle contraction.

Tests for the fractional active-site model in Flp site-specific recombination. Assembly of a functional recombination complex in half-site and full-site strand transfer

The Arg191-His305-Arg308 (the RHR triad) and Tyr343 of Flp site-specific recombinase correspond to the invariant tetrad residues of the integrase family of proteins. Flp mutants altered at these positions are blocked at the strand cleavage or the strand exchange step of recombination. Hybrid half-site-recombinase complexes formed by step-arrest mutants of Flp have revealed that an Flp monomer occupying a half-site does not cleave that half-site but rather cleaves a half-site occupied by a second Flp monomer. This trans-DNA cleavage is neatly accommodated by a model in which an Flp active site is assembled by contribution of amino acid residues from at least two protein monomers. Using a combination of wild type Flp, single, double, and triple step-arrest Flp mutants, critical predictions of the fractional active-site model have been verified. First, a wild type monomer paired with an RHR triad-Tyr343 double mutant is a catalytically inactive combination. Second, each pairwise combination of a single, double, or triple RHR mutant with Flp (Y343F) yields approximately equivalent levels of catalytic complementation. Half-site to half-site and half-site to full-site crosses suggest that execution of a strand transfer event within a half-site and between a half-site and a full site requires dimeric and tetrameric Flp configurations, respectively.

Dual control of heat shock response: involvement of a constitutive heat shock element-binding factor

Heat shock factor (HSF) has been implicated as the key regulatory protein in the heat shock response. Our studies on the response of rodent cells to heat shock or sodium arsenite indicate that a high level of HSF-DNA-binding activity, by itself, is not sufficient for the induction of hsp70 mRNA synthesis; furthermore, a high level of HSF binding is also not necessary for this induction. Analysis of the binding of protein factors to the heat shock element (HSE) in extracts of stressed rodent cells indicates that the regulation of heat shock response involves the heat-inducible HSF and a constitutive HSE-binding factor. Our results also suggest that overexpression of human hsp70 may decrease the level of heat-induced HSF-HSE-binding activity in rat cells.

Potentiation of miniature endplate potential frequency by ATP in Xenopus tadpoles

1. Extracellular application of ATP (1 mM), a substance co-stored and co-released with acetylcholine in peripheral nervous systems, potentiated the spontaneous secretion of acetylcholine (ACh) but had no effect on the amplitude and decay time constant of miniature endplate potentials (m.e.p.ps) at neuromuscular synapses in Xenopus tadpoles. 2. alpha,beta-Methylene ATP (0.3 mM) and GTP (1 mM) were also effective in increasing m.e.p.p. frequency. On the other hand, ADP, AMP and adenosine (all at 1 mM) decreased m.e.p.p. frequency. 3. Unlike the transient effect of ATP analogue and GTP on m.e.p.p. frequency, the phorbol ester TPA (2 microM) which is a protein kinase C activator, increased m.e.p.p. frequency consistently and the effects lasted as long as the presence of TPA. 4. Staurosporine (0.5 microM) and H-7 (10 microM), which are protein kinase C inhibitors, each decreased the basal level of m.e.p.p. frequency and markedly inhibited the effects of both ATP and TPA. 5. These results suggest that there is a basal activity of cytosolic protein kinases in the nerve terminals of Xenopus tadpoles and the effect of ATP is probably mediated by the binding of membrane surface purinoceptors which in turn activates cytosolic protein kinases and increases ACh release.

Protection by moxibustion against experimental hyperbilirubinemia and cholangitis in rats

The effects of moxibustion on experimental hyperbilirubinemia and cholangitis were studied in male rats (n = 33). The experimental group were treated with moxibustion, 18, 12 and 6 hours prior to and 6, 12 and 18 hours after challenge with oral alpha-naphthylisothiocyanate (ANIT, 100 mg per kg). Rats were sacrificed 48 hours after challenge. Serum and liver samples were taken for biochemical and histological analysis, respectively. The results revealed that rats treated with ANIT exhibited elevations in bilirubin, SGOT and SGPT as well as cholangitis. In rats receiving moxibustion and ANIT, biochemical and morphological parameters of liver injury were significantly reduced. Thus, this study shows that moxibustion therapy may be able to prevent ANIT-induced hyperbilirubinemia and cholangitis.

Functional analysis of Box II mutations in yeast site-specific recombinases Flp and R. Significance of amino acid conservation within the Int family and the yeast sub-family

The site-specific recombinases Flp and R from Saccharomyces cerevisiae and Zygosaccharomyces rouxii, respectively, are related proteins that share approximately 30% amino acid matches. They exhibit a common reaction mechanism that appears to be conserved within the larger Integrase family of site-specific recombinases. Two regions of the proteins, designated as Box I and Box II, harbor, in addition to amino acid conservation, a significantly high degree of nucleotide sequence homology within their coding segments. Box II also contains two amino acids, a histidine and an arginine, that are invariant throughout the Int family. We have performed functional analysis of Flp and R variants carrying point mutations within the Box II segment. Several positions within Box II can tolerate substitutions with no effect, or only modest effects on recombination. Alterations of the Int family residues, His305 and Arg308, in the R protein lead to the arrest of recombination at the strand cleavage or the strand exchange step. This is very similar to previously observed "step-arrest" phenotypes in Flp variants altered at these positions and has strong implications for the catalytic mechanism of recombination. Flp and R variants at His305 and His309 can be complemented in half-site strand transfer by a corresponding Tyr343 to phenylalanine variant. In contrast to Arg308 Flp variants, which are efficiently complemented in half-site strand transfer by Flp(Y343F), no strong complementation has been observed between Arg308 variants of R and R (Y343F).

Glycan components in the glycoinositol phospholipid anchor of human erythrocyte acetylcholinesterase. Novel fragments produced by trifluoroacetic acid

Inositol glycans were prepared from reductively radiomethylated human erythrocyte acetylcholinesterase by sequential treatment with Proteinase K, methanolic KOH, and phosphatidylinositol-specific phospholipase C. Four glycans denoted alpha-delta were resolved by anion exchange high performance liquid chromatography (HPLC). Each glycan was subjected to hydrolysis in 4 M trifluoroacetic acid, and their hexose and hexose phosphate compositions were determined by anion exchange HPLC. The predominant glycan alpha showed a relative stoichiometry of 2 mannoses, 1 mannose 6-phosphate, 1 radiomethylated glucosamine, 1 radiomethylated ethanolamine, and 1 inositol. In contrast, the stoichiometry of glycan beta was 1 mannose, 2 mannose 6-phosphates, 1 radiomethylated glucosamine, 2 radiomethylated ethanolamines, and 1 inositol. Glycans alpha and beta were analyzed by electrospray ionization-mass spectrometry, and respective parent ions of m/z 1266 and 1417 were observed. The fragmentation pattern produced by collision-induced dissociation mass spectrometry of these parent ions was consistent with a common linear core glycan sequence prior to radiomethylation of ethanolamine-phosphate-mannose - mannose - mannose - glucosamine - inositol. Glycan alpha contained a single additional radiomethylated phosphoethanolamine branching from the mannose adjacent to glucosamine, whereas glycan beta contained two additional radiomethylated phosphoethanolamines, one branching from each of the mannoses nearest to glucosamine. Trifluoroacetic acid hydrolysis did not cleave within the N,N-dimethylglucosamine-inositol-phosphate moiety in these glycans, and this component was resolved by anion exchange HPLC and structurally confirmed by mass spectrometry. Dephosphorylation of this component by treatment with 50% HF produced N,N-dimethylglucosamine-inositol, and this conjugate was shown to have a characteristic elution time on cation exchange chromatography in an amino acid analyzer. Both of these fragments involving an intact radiomethylated glucosamine-inositol bond are proposed as new diagnostic indicators in the search for minor glycoinositol phospholipids in cells and tissues.

Functional analysis of box I mutations in yeast site-specific recombinases Flp and R: pairwise complementation with recombinase variants lacking the active-site tyrosine

The site-specific recombinases Flp and R from Saccharomyces cerevisiae and Zygosaccharomyces rouxii, respectively, are related proteins that belong to the yeast family of site-specific recombinases. They share approximately 30% amino acid matches and exhibit a common reaction mechanism that appears to be conserved within the larger integrase family of site-specific recombinases. Two regions of the proteins, designated box I and box II, also harbor a significantly high degree of homology at the nucleotide sequence level. We have analyzed the properties of Flp and R variants carrying point mutations within the box I segment in substrate-binding, DNA cleavage, and full-site and half-site strand transfer reactions. All mutations abolish or seriously diminish recombinase function either at the substrate-binding step or at the catalytic steps of strand cleavage or strand transfer. Of particular interest are mutations of Arg-191 of Flp and R, residues which correspond to one of the two invariant arginine residues of the integrase family. These variant proteins bind substrate with affinities comparable to those of the corresponding wild-type recombinases. Among the binding-competent variants, only Flp(R191K) is capable of efficient substrate cleavage in a full recombination target. However, this protein does not cleave a half recombination site and fails to complete strand exchange in a full site. Strikingly, the Arg-191 mutants of Flp and R can be rescued in half-site strand transfer reactions by a second point mutant of the corresponding recombinase that lacks its active-site tyrosine (Tyr-343). Similarly, Flp and R variants of Cys-189 and Flp variants at Asp-194 and Asp-199 can also be complemented by the corresponding Tyr-343-to-phenylalanine recombinase mutant.

Glucocorticoids exacerbate hypoxic and hypoglycemic hippocampal injury in vitro: biochemical correlates and a role for astrocytes

The acute secretion of glucocorticoids is critical for responding to physiological stress. Under normal circumstances these hormones do not cause acute neuronal injury, but they have been shown to enhance ischemic and seizure-induced neuronal injury in the rat brain. Using fetal rat hippocampal cultures, we asked whether hypoxic and hypoglycemic cell damage in vitro could be exacerbated by direct exposure to corticosterone (CORT). Each of these insults alone damaged neuronal cells, whereas 4-6 h of hypoxic treatment could damage age-matched astrocytes if glucose was reduced or omitted. Ischemic-like injury to both cell types could be attenuated by pretreatment with high (30 mM) glucose. Exposure to 100 nM CORT did not affect cell viability under control conditions but enhanced both hypoxic and hypoglycemic neuronal injury. In both cases, pretreatment with high glucose abolished this CORT-mediated synergy. In astrocyte cultures, CORT exacerbated both hypoxic and hypoglycemic injury and this effect was also attenuated by high-glucose pretreatment. Identical 24-h CORT treatment caused a 13% reduction in glucose uptake in astrocytes and a 38% reduction in glycogen content, without affecting the level of intracellular glucose. Thus, CORT could endanger both neurons and astrocytes in mixed hippocampal cultures and this effect emerged only under conditions of substrate depletion. The metabolic disruption in astrocytes by CORT further suggests that the ability of CORT to exacerbate neuronal injury may be due in part to impaired glial cell function.

Glucocorticoids inhibit glucose transport and glutamate uptake in hippocampal astrocytes: implications for glucocorticoid neurotoxicity

Glucocorticoids (GCs), the adrenal steroid hormones secreted during stress, can damage the hippocampus and impair its capacity to survive coincident neurological insults. This GC endangerment of the hippocampus is energetic in nature, as it can be prevented when neurons are supplemented with additional energy substrates. This energetic endangerment might arise from the ability of GCs to inhibit glucose transport into both hippocampal neurons and astrocytes. The present study explores the GC inhibition in astrocytes. (1) GCs inhibited glucose transport approximately 15-30% in both primary and secondary hippocampal astrocyte cultures. (2) The parameters of inhibition agreed with the mechanisms of GC inhibition of glucose transport in peripheral tissues: A minimum of 4 h of GC exposure were required, and the effect was steroid specific (i.e., it was not triggered by estrogen, progesterone, or testosterone) and tissue specific (i.e., it was not triggered by GCs in cerebellar or cortical cultures). (3) Similar GC treatment caused a decrease in astrocyte survival during hypoglycemia and a decrease in the affinity of glutamate uptake. This latter observation suggests that GCs might impair the ability of astrocytes to aid neurons during times of neurologic crisis (i.e., by impairing their ability to remove damaging glutamate from the synapse).

Domain of a yeast site-specific recombinase (Flp) that recognizes its target site

Binding of a partial proteolytic digest by V8 enzyme of the yeast site-specific recombinase Flp to its target site gives rise to DNA-protein complexes that are smaller than those produced by the full-sized protein. The smallest of these complexes (occupancy of one peptide monomer per site) contains either one of two polypeptides (32 and 28 kDa) of the V8 digestion mixture. The amino termini of both polypeptides map to Ser-129 of Flp, corresponding to V8 cleavage at Glu-128. The relative mobilities of the complexes formed by the V8 peptides indicate that they lack the sharp substrate bend that is characteristic of Flp-derived complexes. A hybrid protein consisting of the amino-terminal one-third of the R recombinase (from Zygosaccharomyces rouxii) and the carboxyl-terminal two-thirds of Flp recognizes the Flp target site.

Cytogenetic study of twenty-two intracranial tumors

G-banded chromosomal analysis was performed on primary cultures of 22 intracranial tumors, including eight astrocytomas, nine meningiomas, two dermoid cysts, one acoustic neuroma, one pineal teratoma and one eosinophilic granuloma. One or more chromosomally abnormal clones were observed in 6 (75%) gliomas and 5 (56%) meningiomas. There was no chromosomal abnormality found in one of the dermoid cysts, the acoustic neuroma or the eosinophilic granuloma. A teratoma and a grade IV glioma had heterogeneous hyperdiploid karyotypes. Furthermore, astrocytomas displayed nonrandom loss of chromosomes #19, #21, #22 and Y. In meningiomas, characteristic changes involving chromosome 22 were found in 5 tumors. One meningioma had a ring chromosome in addition to chromosomal loss. With our culture and harvesting techniques, cytogenetic studies can be successfully performed on nearly all intracranial tumor explants, including those derived from small biopsy specimens. Also, in our study, specific nonrandom chromosomal anomalies were found.

An interactive computer graphics system for the design of molded and orthopedic shoe lasts

The Department of Computer Science at North Carolina State University, with support from the Department of Veterans Affairs and National Aeronautics and Space Administration (NASA) Langley Research Center, has developed an interactive graphics program for the development of shoe lasts from digitized images of feet or digitized images of commercial shoe lasts. The program runs on a Sun 3/260 computer with a TAAC-1 graphics accelerator. The program contains operations for region addition and deletion, techniques for narrowing the ankle area, methods for toe extension, operations to allow for shoe inserts, etc. Once the operations by the user are complete, the program will resample the resulting last in a 512 x 512 array. The user is then allowed to select an error tolerance which will guide a data reduction program to represent the last as Coons patches. These patches are then transmitted to a milling machine which will cut the last.

Hemorrhagic fever with renal syndrome. Separation of human peripheral blood T and B cells and detection of viral antigen

In this study, total blood lymphocytes were prepared from patients with hemorrhagic fever with renal syndrome (HFRS) by a density gradient on Ficoll-Hypaque. T and B cells were then purified by passing the total lymphocytes over a nylon wool column. The purities of total lymphocytes, T cells and B cells were 97.8 +/- 2.3%, 91.6 +/- 4.5% and 74.2 +/- 12.1%, respectively. Also, after modification of cell fixation and smear drying, the number of cells were increased and the time needed for slide preparation was shortened. Detection of viral antigen by immunofluorescence assay using monoclonal antibodies to Hantavirus (HTNV) showed that the total lymphocytes. T cells and B cells were infected by HTNV during the early stages of HFRS and no specific fluorescence was seen in the cells from the late diuretic phase to convalescent phase. The results suggest that virus replication in blood lymphocytes may partly contribute in the early stages to the impairment of cell immune response and in vivo spread of HTNV to its target sites.

[Preparative separation of borneol and isoborneol in bingpian by dry-column chromatography]

Borneol (I) and isoborneol (II) in synthetic Bingpian are separated by means of dry-column chromatography (DCC). The sample mixed with a small amount of adsorbent is transferred to the top of the column (50 x 4 cm i.d.) packed with silica gel (200 mesh) and developed with petroleum ether-ethyl acetate-chloroform (20:2: 6) until the solvent has spread from the top to the bottom of column. The zones of I and II can be located by the corresponding Rf of TLC. They are then eluted separately with absolute alcohol. After the concentration of the eluent by vacuum distillation, the crystals of I and II are isolated from the residual solution on standing. The purities of I and II are tested with known specimens by TLC.

[Evaluation of 3 chest leads CM5, CC5, and CL5 and factors which influence the results]

In recent few years, many authors had discussed the possibilities of using bipolar precordial leads to replace lead V5 in diagnosing anterior wall myocardial ischemia. But there still remains some problems to be solved: (1) Are there any difference between bipolar precordial leads and lead V5 in wave forms? (2) What kind of factors influence the ST deviation? 36 patients were studied by comparing unipolar lead V5 with respect to three different bipolar chest leads CM5, CC5, CL5 both in lying and sitting positions. We found that: (1) The differences is least significant between bipolar CC5 and lead V5 while it is most significant between bipolar lead CM5 and lead V5. (2) The deviation of ST segment in bipolar leads is affected both by potential at negative electrode as well as potential at positive electrode. Statistical analysis revealed that ST segment is positively related to the potential on positive electrode and negatively related to the potential on negative electrode. For this reason, therefore, in the view point of most comparable ST deviation with lead V5 for monitoring of myocardial ischemia, it is advisable to locate the negative electrode at the site on chest with least potential. Usually we place the negative electrode on V6R to compose a bipolar lead CC5.

Improvement in hearing among otherwise normal schoolchildren in iodine-deficient areas of Guizhou, China, following use of iodized salt

According to a survey in Guizhou province of China, the average hearing level of otherwise normal schoolchildren in an area of endemic iodine-deficient goitre and cretinism was significantly poorer than in a non-endemic control area. After iodine prophylaxis for three years, audiometric tests showed that the average hearing level had improved and approached that of the non-endemic controls. In addition, mean values for thyroid function tests were restored to within the normal range. It is suggested that the most likely cause of the poorer hearing level among the ostensibly normal schoolchildren in endemic areas is subclinical hypothyroidism due to prolonged severe iodine deficiency.