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Biomedical subjects

Z Hu

Publications and source records attributed to Z Hu.

At least 271 records · Page 15Linked to original sources
PubMed1997

[Surgical treatment of traumatic facial paralysis].

The paper reviews 27 cases of traumatic facial paralysis undergone surgical treatment. Most of the cases showed injuries to the horizontal and perigeniculate segments of the facial nerve. All cases have been followed up for 6 months to 2 years. Complete recovery occurred in 20 of the cases and partial recovery in 7 cases (II in 2, III in 5). Trans-mastoid/attic approach was used which yielded exposure of the geniculate ganglion and distal part of the labyrinthine segment of the nerve. Indications and surgical approach were discussed.

Adolescent↗
PubMed1997

[Cloning and expression in Escherichia coli of an alkaline and thermostable exolipase from Pseudomonas pseudoalcaligenes].

A gene coding for an alkaline and thermostable exolipase of Pseudomonas pseudoalcaligenes was cloned into Escherichia coli LE392 by inserting Sau3 AI-generated DNA fragments into the BamHI site of pIJ285. Four colonies with esterase and lipase activities on the tributyrin agar plate were isolated by screening the constructed pseudomonas pseudoalcaligenes genomic library. Only one out of the four positive colonies showed lipase activity on the agar plate contatining olive oil and Rhodamine-B. Subclones of the 45 kb insert carrying lipase gene was obtained in E. coli HB101 using pUC118 as a vector, two of which (HB101 (pHZ1402) and HB101 (pHZ1403)), retained lipase activity, but the level seems to be different. They carried 3.0 kb and 2.9 kb inserts with a 2 kb overlapping sequence. The lipase activity of HB101 (pHZ1403) is about 4 times higher than that of HB101 (pHZ1402), as 5 times as that of original strain P. pseudoalcaligenes.

English Abstract↗
PubMed1997

[The stress reaction induced by intensive noise exposure in rats].

To study the effects of sustained intensive noise on rats, fifty SD male rats were randomly divided into: control group and 1 d, 3 d, 7 d and 14 d noise exposure groups (120 dBSPL, broadband noise, 2 h daily). The results showed that after noise exposure, the ACTH level and the corticosterone level in serum increased, but the content of DA in diencephalon decreased, the weight of adrenal gland increased, while that of thymus and spleen decreased. Change of weight of adrenal gland and thymus became maximum after 7d-exposure. The ACTH level in serum and the content of DA in diencephalon decreased and the later reached the lowest value and the weight of adrenal gland and thymus returned to normal level after 14 d exposure. It indicated that the acute response began to decrease after 7d-exposure, and the response turned into a chronic inhibitory state after 14d-exposure.

Adrenal Glands↗
PubMed1997

[Effect of noise in submarine compartment on signal discrimination and arithmetic performance].

To study the effects of noise level in submarine compartment on signal discrimination and arithmetic performance, experiments were carried out on 13 subjects. The results showed that as noise level raised from moderate (73 dBA) to higher levels (85-92 dBA), work efficiency showed a progressive decrease, but when noise level reached 96 dBA the decrease in efficiency reached a steady state. The results indicated that impairment of efficiency apparently occurred at a level of 85 dBA and that the interference effect of noise was more pronounced on task performance with mental strain.

Auditory Perception↗
PubMed1997

[The bred technique of Zaocys dhumnades].

This paper reports the observational data on the laying egg, hatching, life habit, relationship between capacity for eating and growth speed of Zaocys dhumnades bred in enclosure-like garden of snake, summarizes an available breeding technique.

Animal Feed↗
PubMed1997

[Relationship between variations of temperature and humidity with reproduction of medical meloids].

This paper reports the relationship between variations of temperature and humidity with reproduction of two medical meloids (Mylabris phalerata, M. cichorii). The results show: for the copulation of two meloids, the suitable temperature is 22-28 degrees C, humidity 26-90%; for the suitable temperature and humidity of their oviposition, M. phalerata 26-28 degrees C and 60-68%, and M. cichorii 23-26 degrees C and 72-78%, respectively; for incubation, M. phalerata is 26-28 degrees C and 70-75% respectively, and M. cichorii must undergo the high and lower variation of temperature, the efficacious accumulative temperature must get of 1680.85 day. degrees C.

Animals↗
PubMed1997

[Observation on the life habit of Epicata aptera].

Epicata aptera reproduces one generation every year. Adults arise in the last ten-day period of May, mate and lay egg in the first ten-day period of June. They mate and lay egg 1-3 sequence every year, lay egg 108-269 grains every sequence. Period of their laying egg undergoes 48-78 days. Larva have six age period. They take false pupas live through the winter. Complete generations undergo 348-394 days.

Animals↗
PubMed1997

[Advances in research of hydrophobic interaction chromatographic packings].

Hydrophobic interaction chromatography (HIC) is an attractive method for protein purification. The paper gives a review on the characteristics of HIC packings, including matrices and hydrophobic ligands. The efficiencies for protein separations were compared for different HIC packings. The present situation and the developing trends of the preparative HIC packings were described.

Animals↗
PubMed1997

[Gas chromatographic analysis of fatty acids in phosphatidylglycerol from needles of two crosses of Chinese Fir].

This paper reports a method for determination of fatty acids in phosphatidylglycerol from needles of two crosses of Chinese Fir with different cold-resistance. Some simplifications and improvements for analytical method of DEAE CL-6B column chromatography and of silica thin layer chromatography were also discussed. After being extracted with chloroform and methanol, phosphatidylglycerol was isolated from the general lipid extract by using DEAE CL-6B IEC and Silica TLC. Quantitative analysis was conducted by gas chromatography on a DB-FFAP (30m x 0.32mm i.d.) column. The results showed that there was a difference in the ratio of fatty acid (18:1+18:2+18:3)/[16:0+16:1(3t)] between the two crosses of Chinese Fir with different cold-resistance, 1.12 for that with higher cold-resistance and 1.25 for that with lower cold-resistance. A special fatty acid 16:1(3t) was found in both of the two crosses.

Chromatography, Gas↗
PubMed1997

[Cloning and squencing of human thrombopoietin (hTPO) cDNA and it's expression in COS-7 cells].

Two hTPO cDNA segments (N-terminal and C-terminal) were amplified from human fetal liver mRNA by using separate reverse-transcription PCR reactions, and cloned into pUC19. Their sequences were identical with that previously reported. Then the full length cDNA of hTPO was obtained from the two cDNA fragments, cloned into the shuttle vector pSVK3 and transiently expressed in COS-7 cells. The activity of the expression product was demonstrated with the stimulation of CFU-Meg.

Animals↗
PubMed1997

[Changes of early renal function before and after using mannitol in patients with cerebral apoplexy].

The alteration of renal function after initiation of mannitol infusion were monitored in 20 patients with cerebrovascular accident to evaluate whether mannitol has nephrotoxicity effects. Serum creatinine and urea nitrogen were increased after initiation of mannitol infusion, but hadn't reached stagistical significance. Urinary and serum alpha 1-microglobulin, beta 2-microglobulin and urinary NAG, gamma-GT were significantly increased after 5-10 days successive infusion of mannitol (P < 0.05). The results suggest that the acute nephrotoxicity effect of mannitol should not be ignored.

Adult↗
PubMed1996

Purification and characterization of cytosolic pyruvate kinase from leaves of the castor oil plant.

Cytosolic pyruvate kinase (PKc) from leaves of the castor oil plant (Ricinus communis L.) has been purified 3900-fold to apparent homogeneity and a final specific activity of 51 mumol of pyruvate produced/min/mg protein. PAGE, immunoblot, and gel filtration analyses of the final preparation indicated that this enzyme is an alpha 2 beta 2 heterotetramer of about 250 kDa that is composed of an equivalent ratio of 57- and 56-kDa subunits. The enzyme was relatively heat-stable and displayed a broad pH optimum of approximately 6.5. However, optimal efficiency in substrate utilization [in terms of Vmax/Km for phosphoenolpyruvate (PEP) or ADP] occurred at pH 7.5. Enzyme activity was absolutely dependent upon the simultaneous presence of bivalent and a univalent metal cation, with Mg2+ and K+ fulfilling this requirement. Hyperbolic saturation kinetics were observed with PEP, ADP, and K+, whereas Mg2+ binding exhibited positive cooperativity. Mg2 citrate, oxalate, and glutamate were the most effective inhibitors at pH 7.5. Inhibition by these compounds was more pronounced at pH 7.5 than at pH 6.5 and they yielded additive inhibition when tested in pairs. Aspartate functioned as an activator by facilitating the binding of PEP and relieving the inhibition of PKc by glutamate. The in vivo activity of leaf PKc is probably regulated by the relative cytosolic levels of citrate, glutamate, and aspartate. This provides a possible rationale for the known activation of leaf PKc that occurs during periods of enhanced ammonia assimilation. Together with our previous studies, the results also indicate that castor oil plant PKc exists as tissue-specific isoforms that demonstrate substantial differences in their respective physical and/or kinetic and regulatory properties.

Animals↗
PubMed1996

Characterization of expression of phosphofructokinase isoforms in isolated rat pancreatic islets and purified beta cells and cloning and expression of the rat phosphofructokinase-A isoform.

Phosphofructokinase (PFK) plays a key role in regulating glycolytic flux, and the mammalian enzyme is a tetramer. Three monomeric isoforms are encoded by separate genes, are differentially expressed in specific tissues, and are designated by tissues in which they are most abundant (A, muscle; B, liver; and C, brain). Glucose-induced insulin secretion from pancreatic islets requires glucose transport into islet beta-cells and glycolytic metabolism. Little is known about islet PFK isozymes, but the possibility that PFK-A is expressed in beta-cells is of interest because that isoform is thought to govern glycolytic oscillations and to interact with a metabolically activated beta-cell phospholipase A2 enzyme. Using as probe a PCR product generated from rat islet RNA with primers designed from the human PFK-A sequence, we have cloned a full-length PFK-A cDNA from a rat islet cDNA library. The rat PFK-A deduced amino-acid sequence is 96% identical to that of human PFK-A, and all residues thought to participate in substrate or allosteric effector binding are conserved between the two sequences. The rat PFK-A amino-acid sequence is 69% and 68% identical to those for rat PFK-B and rat PFK-C, respectively, and differences in residues involved in binding of allosteric effectors were observed among the three isoforms. Rat PFK-A expressed as a glutathione-S-transferase fusion protein was recognized by antibodies raised against a peptide in the PFK-A sequence. Expression of PFK isoform mRNA species was examined by RT-PCR in rat islets, in purified populations of beta-cells prepared by fluorescence-activated cell sorting (FACS), and in RIN-m5F insulinoma cells, all of which expressed mRNA species for PFK-A, -B, and -C isoforms. PFK-A mRNA was expressed at much lower levels in an islet alpha-cell-enriched population. Interleukin-1 impairs islet glucose metabolism and insulin secretion and was found to induce a specific decline in islet expression of PFK-A mRNA. These findings establish the sequence of rat PFK-A, demonstrate that it is expressed in FACS-purified islet beta-cells, and suggest that its expression is regulated by a cytokine which influences insulin secretion.

Amino Acid Sequence↗
PubMed1996

The alteration of glucocorticoid receptor-immunoreactivity in the rat forebrain following short-term and long-term adrenalectomy.

To examine the effect of short-term and long-term adrenalectomy (ADX) on the glucocorticoid receptor (GR) expression, we performed an immunohistochemical study on the rat forebrain. One day after ADX, the GR-immunoreactivity significantly decreased or disappeared in most forebrain structures, while relatively strong GR-immunoreactivity was still found within the hypothalamus especially in the arcuate nucleus (ARC) and the parvocellular paraventricular nucleus (PVN). Two weeks following ADX, GR-immunoreactive cells disappeared in many structures of the forebrain including most parts of hypothalamus while moderate GR-immunoreactivity was still observable in the ARC and PVN. More than 3 months after ADX, the rats still survived when they received replacement of corticosterone during the first 2 weeks following the operation. Moderate GR-immunoreactivity in the ARC and PVN of the hypothalamus was exhibited whereas no immunoreactive cells remained in the cerebral cortex, thalamus and other forebrain structures when these animals showed obvious cell death in the granule cells of the dentate gyrus, identified with the silver impregnation method for degenerating cells. Massive cell loss in this hippocampal region is an indicator of a complete ADX, in addition to the blood corticosterone level. These results demonstrate topographic differences of GR expression in the rat forebrain after ADX with only continuous immunoreactivity in the ARC and PVN of the hypothalamus, suggesting that some neurons in the ARC and PVN could keep active GR probably in order to maintain their survival after removing the adrenal gland.

Adrenalectomy↗
PubMed1996

GDNF-induced activation of the ret protein tyrosine kinase is mediated by GDNFR-alpha, a novel receptor for GDNF.

We report the expression cloning and characterization of GDNFR-alpha, a novel glycosylphosphatidylinositol-linked cell surface receptor for glial cell line-derived neurotrophic factor (GDNF). GDNFR-alpha binds GDNF specifically and mediates activation of the Ret protein-tyrosine kinase (PTK). Treatment of Neuro-2a cells expressing GDNFR-alpha with GDNF rapidly stimulates Ret autophosphorylation. Ret is also activated by treatment with a combination of GDNF and soluble GDNFR-alpha in cells lacking GDNFR-alpha, and this effect is blocked by a soluble Ret-Fc fusion protein. Ret activation by GDNF was also observed in cultured embryonic rat spinal cord motor neurons, a cell type that responds to GDNF in vivo. A model for the stepwise formation of a GDNF signal-transducing complex including GDNF, GDNFR-alpha, and the Ret PTK is proposed.

Amino Acid Sequence↗