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Biomedical subjects

F Zhang

Publications and source records attributed to F Zhang.

At least 487 records · Page 27Linked to original sources
PubMed1996

[The changes of vasoactive intestinal peptide somatostatin and pancreatic polypeptide in blood and CSF of acute cerebral infarction patients and the effect of acupuncture on them].

VIP, SS and PP which exist in gastrointestinal tract and CNS might be to play an important role in nervous system as neurotransmitters of neuromediaters. There have been a few of reports about their changes in plasma and CSF in ICVD. The effects of acupuncture, which was used in treatment of ICVD with good efficiency, on VIP, SS and PP have not been known. For researching their changes in ICVD and effects of electro-acupuncture on them, and finding the mechanism of acupuncture in treatment of ICVD, the study was performed. The levels of VIP, SS and PP in 64 patients with acute cerebral infarction were determined. The points of acupuncture were Quchi (LI 12), Waiguan (SJ 5), Huantiao (BG 30), and Zusanli (ST 36). The routine treatment included dextran, nicotinic acid, aspirin, dipyridamole and radix salviae miltiorrhizae composita. The CSF and blood were taken before the begining of treatments and after a course of treatment. The level of VIP, SS and PP were measured by radiommunoassay. Results showed the level of CSF VIP in the patients was significantly lower as compared with controls. The level of plasma SS in the patients was lower, but the difference was not significant as compared with controls, and level of plasma PP in the patients was significantly increased when it was compared with controls. After electro-acupuncture treatment, in patients with good efficiency, CSF VIP recovered to normal level and the levels of plasma and CSF SS were significantly increased, while the level of plasma PP had no significant change. The results suggest that acupuncture might regulate the disturbances of metabolism of VIP and SS in CNS.

Acupuncture Points↗
PubMed1996

[Studies on semen quality in workers exposed to manganese and electric welding].

Three hundred and ten workers were selected to study the effects of manganese and electric welding on male reproductive function, with 211 occupationally exposed to manganess and electric welding fume and 99 controls. Concentrations of manganese and welding fume in the air of the workplace were 0.14-5.5 mg/m3 and 6.5-82.3 mg/m3, respectively. Semen concentrations of manganese, copper, chromium, nickel, and iron in workers employed in electric welding were significantly higher than those in controls. Time from ejaculation to liquefaction of semen in exposed workers was longer than that in controls, and volume of semen, sperm count, viable sperm count and percentage were significantly lower in the exposed workers than in the controls. Stepwise regression analysis suggests a direct toxic effect of manganese on sperm production.

Adult↗
PubMed1996

[Determination of visual function after implantation of intraocular lens].

OBJECTIVE: To understand whether the binocular visual function could be restored after posterior chamber intraocular lens (IOL) implantation. METHODS: The visual function including corrected vision, simultaneous perception, fusion, stereoacuity, aniseikonia and retinal correspondence point were determined for 50 cases (64 eyes) after the surgery. RESULTS: The corrected visual acuities were 0.6 or better. Visual acuities of 1.0 or better were achieved in 65% and 0.6-0.9 in 35% of the eyes. All patients obtained simultaneous perception and fusion function. The near stereoacuity of 50 cases showed foveal stereoacuity < or = 60 seconds in 23 cases (46%), macular stereoacuity 80-200 seconds 10 cases (20%) and peripheral stereoacuity 400 seconds 17 cases (34%). The far stereoacuity of 50 cases comprised 34 cases of foveal stereoacuity (68%), 9 cases of macular stereoacuity (18%) and 7 cases of peripheral stereoacuity (14%). The postoperative retinal correspondence points were normal. There was no aniseikonia in 35 cases, except 15 cases of aniseikonia which was within normal tolerable limits. CONCLUSION: When binocular corrected vision is > or = 0.4 with ocular alignment, the binocular visual function could be restored for varying degrees.

Adolescent↗
PubMed1996

[The relationship of function and pathology of submandibular gland with sialolithiasis].

Submandibular glands with sialolithiasis are analysed histopathologically. The formation of the calculi of the submandibular glands may be related to the sialoadentitis and to the changes of saliva composition. Mineralization of the organic matrix may be one of the cause of calculus formation. By comparison of the glandular function with the pathology of the gland, it shows that the reduction of glandular function is associated with the severity of grandular inflammation. When function index is normal, grandular inflammation is in the Stage I or II, while it decreases or zero, grandular inflammation is in the Stage III or IV. Glandular function index may predict the severity of grandular inflammation.

Adult↗
PubMed1996

[Analysis of short-term effects of short-course intermittent chemotherapies of the World Bank Loaned Project].

OBJECTIVE: To explore the characteristic features of sputum conversion during short-course intermittent chemotherapies and the measures of keeping high cure rates. METHODS: 1,350 smear positive pulmonary tuberculosis cases in the ten research pilot counties of Liaoning province from 1992 to 1993 were selected to receive short-course intermittent chemotherapies under full-course supervision. The project was supported by the World Bank. The sputum specimens of the cases were regularly examined. The effects of the chemotherapies and the measures of keeping high cure rate were evaluated according to the situation of sputum conversion. RESULTS: The cure rates of initial and relapse smear positive cases were 92.5% and 74.6% respectively. It is also found that the therapeutic effects were affected by the situation of sputum conversion at the end of intensive phase. The cure rate of the cases who failed in initial treatment and continued retreatment was only 54%, which was obviously lower than that of the other retreatment cases. CONCLUSION: Strengthening the treatment and management at the intensive phase can increase the cure rate. It is recommended that more rational regimens should be studied and provided to those who fail in initial treatment to improve the therapeutic effects.

Antibiotics, Antitubercular↗
PubMed1995

Molecular cloning of a novel high molecular weight mucin (MG1) from human sublingual gland.

A human sublingual gland cDNA library was screened with a polyclonal antiserum against deglycosylated MG1 and a positive clone, pSM2-1, was isolated which codes for 196 amino acids in the carboxyl-terminal region of this mucin. This region is cysteine-rich and contains a C2-like domain upstream of the extreme carboxyl-terminal domain in which the arrangement of cysteines is nearly identical to that in human von Willebrand factor, human intestinal mucin MUC2, human tracheobronchial mucin MUC5 and porcine and bovine submaxillary gland mucins. Northern analyses with pSM2-1 showed MG1 transcripts are abundant in sublingual gland and barely detectable in submandibular gland. This study provides the first primary sequence data on human salivary mucin MG1 and the significance of the results is discussed with respect to the biosynthesis and differential expression of MG1 in human salivary glands.

Amino Acid Sequence↗
PubMed1995

Two highly specialized histone H1 proteins are the major chromosomal proteins of the sperm of the sea anemone Urticina (Tealia) crassicornis.

The sperm nuclear basic proteins (SNBPs) from a sea anemone (Urticina crassicornis) have been isolated and characterized for the first time. They consist of two sperm-specific members of the histone H1 family with Mr 22,700 and 24,600. They amount to about 60--70% of the total chromosomal sperm proteins. Their amino acid composition and the primary structure of their trypsin-resistant core indicate a strong relation to histone H5 from the nucleated erythrocytes of birds and amphibians as well as to other high sperm-specific H1-like (PL-I) proteins from phylogenetically distant groups. The major presence of histone H1-like protein in the sperm of an organism belonging to such a low phylogenetic group provides experimental support to the hypothesis that SNBPs may all have evolved from a primitive histone precursor.

Amino Acid Sequence↗
PubMed1995

Lateral mobility of Fc gamma RIIa is reduced by protein kinase C activation.

The lateral mobility of membrane proteins can reflect the extent of various protein-protein interactions. Using the fluorescence recovery after photobleaching technique, we have studied the lateral mobility of human Fc gamma RIIa and some Fc gamma RIIa mutants expressed in either P388D1 cells, a mouse macrophage-like cell line, or in Chinese hamster ovary (CHO) cells [1]. After treatment with phorbol myristate acetate (PMA), only the Fc gamma RIIa molecules capable of mediating rapid endocytosis of immune complexes exhibited a reduced lateral diffusion coefficient with respect to untreated controls. Wild type Fc gamma RIIa expressed in CHO cells, and nonfunctional Fc gamma RIIa mutants expressed in P388D1 cells did not show any differences upon PMA treatment. This finding suggests that protein kinase C activation evokes additional protein-protein interactions with the cytoplasmic domain of functional Fc gamma RIIa, which reduced receptor lateral mobility. The identity of these putative interacting proteins and the nature of the interactions remain to be elucidated.

Animals↗
PubMed1995

Hyperosmolarity stimulates prostaglandin synthesis and cyclooxygenase-2 expression in activated rat liver macrophages.

The effect of aniso-osmotic exposure on the level of inducible cyclooxygenase (Cox-2) and on prostanoid synthesis was studied in cultured rat liver macrophages (Kupffer cells). In lipopolysaccharide (LPS)- or phorbol 12-myristate 13-acetate-stimulated Kupffer cells, hyperosmotic (355 mosmol/l) exposure, due to addition of NaCl or impermeant sugars, markedly increased prostaglandin (PG) E2, D2 and thromboxane B2 synthesis in a time- and osmolarity-dependent manner. Increased prostanoid production was observed about 8 h after exposure to LPS in hyperosmotic medium compared to Kupffer cells treated with LPS under normotonic (305 mosmol/l) conditions. A similar stimulatory effect of hyperosmolarity on PGE2 production was also seen when arachidonate was added exogenously. Hyperosmotic stimulation of PGE2 production was accompanied by a strong induction of Cox-2 mRNA levels and an increase in immunoreactive Cox-2, whereas the levels of immunoreactive phospholipase A2 and cyclooxygenase-1 did not change significantly. Dexamethasone, indomethacin and the selective Cox-2 inhibitor, NS-398, abolished the hypertonicity-induced stimulation of PGE2 formation; dexamethasone also prevented the increase in Cox-2 mRNA and protein. The increase of immunoreactive Cox-2 lasted for about 24 h and was also blocked by actinomycin D or cycloheximide, but not by brefeldin A. Tunicamycin or treatment with endoglucosidase H reduced the molecular mass of hypertonicity-induced Cox-2 by 5 kDa. Tunicamycin treatment also suppressed the hypertonicity-induced stimulation of PGE2 production. The hyperosmolarity/LPS-induced stimulation of prostaglandin formation was partly sensitive to protein kinase C inhibition but was not accompanied by an increase in the cytosolic free Ca2+ concentration. The data suggest that osmolarity may be a critical factor in the regulation of Cox-2 expression and prostanoid production in activated rat liver macrophages.

Adenosine Triphosphate↗
PubMed1995

Fatty acid flip-flop in phospholipid bilayers is extremely fast.

The rate of movement of fatty acids (FA) across phospholipid bilayers is an important consideration for their mechanism of transport across cell membranes but has not yet been measured. When FA move undirectionally across phospholipid bilayers, the rapid movement of un-ionized FA compared to ionized FA results in transport of protons. We have previously used this property to show that FA move spontaneously ("flip-flop") across the bilayer of small unilamellar vesicles within approximately 1 s (Kamp & Hamilton, 1992, 1993). This work extends the time resolution of this assay into the millisecond time range by use of stopped flow fluorometry. In small unilamellar vesicles (diameter, approximately 25 nm) at neutral pH, flip-flop of all fatty acids studied (lauric, myristic, palmitic, oleic, and stearic) was > or = 80% complete within 5-10 ms. In large unilamellar vesicles (diameter, approximately 100 nm), the same fatty acids exhibited fast flip-flop but with a measureable rate (t 1/2 = 23 +/- 12 ms). The calculated pseudounimolecular rate constant of the un-ionized FA (kFAH) approximately 15 s-1. There was no dependence of the flip-flop rate on the fatty acid chain length or structure. We also monitored the rate of desorption and transbilayer movement of (anthroyloxy)stearic acid in small unilamellar vesicles. Whereas previous studies suggested slow flip-flop of this FA analogue, the present studies suggest that (anthroyloxy)stearic acid flip-flops rapidly and that earlier studies did not truly measure the transbilayer movement step. These findings further support the view that proteins are not required for translocation of FA across cell membranes.

Arylsulfonates↗
PubMed1995

Structural analysis and comparison of the C-terminal transport signal domains of hemolysin A and leukotoxin A.

NMR spectroscopy was used to study the structure of the C-terminal signal sequences of the bacterial toxins, hemolysin A(HlyA) and leukotoxin A (LktA). The two signals share little sequence homology; however, both can direct toxin transport with equal efficiency. We report here that in a membrane mimetic environment both peptides form two short non-interacting alpha-helices separated by a short loop. This higher order structure may be a common feature of C-terminal signals and may be required for interaction with the membrane associated transporter complex.

Amino Acid Sequence↗
PubMed1995

Decrease of zif-268 and c-fos and increase of c-jun mRNA in the cat areas 17, 18 and 19 following complete visual deafferentation.

We used in situ hybridization to investigate the effect of complete visual deafferentation on immediate early gene expression in adult cat visual cortex. Deafferentation was obtained by unilateral section of the optic tract and sections of both the corpus callosum and anterior commissure. In this model, one hemisphere served as control for the other within the same animal. A decrease in zinc finger protein (zif)-268 and c-fos mRNA was observed in the superficial and deep layers of areas 17 and 18, and all layers of area 19 in the deafferented hemisphere. This decrease, present 3 days after surgery, was maximal after 30 days. An increase of c-jun mRNA was observed in the deep layers of areas 17, 18 and 19 in the deafferented hemisphere 3, 10 and 30 days after surgery. These results suggest that visual input activates zif-268 and c-fos expression and tonically depresses c-jun expression in the primary visual complex yielding similar levels of c-jun and c-fos expression in normal conditions.

Animals↗
PubMed1995

Translational suppression by trinucleotide repeat expansion at FMR1.

Fragile X syndrome is the result of the unstable expansion of a trinucleotide repeat in the 5'-untranslated region of the FMR1 gene. Fibroblast subclones from a mildly affected patient, each containing stable FMR1 alleles with 57 to 285 CGG repeats, were shown to exhibit normal steady-state levels of FMR1 messenger RNA. However, FMR protein was markedly diminished from transcript with more than 200 repeats. Such transcripts were associated with stalled 40S ribosomal subunits. These results suggest that a structural RNA transition beyond 200 repeats impedes the linear 40S migration along the 5'-untranslated region. This results in translational inhibition by trinucleotide repeat expansion.

Centrifugation, Density Gradient↗
PubMed1995

Secretion and circular dichroism analysis of the C-terminal signal peptides of HlyA and LktA.

The secretion of the 107 kDa hemolysin A (HlyA) from Escherichia coli is mediated by membrane proteins hemolysin B (HlyB) and hemolysin D (HlyD). The signal for transport has been mapped to the C-terminal 60 amino acids of the HylA molecule. We have shown previously that the C-terminal 70 amino acids of leukotoxin (LktA) from Pasteurella hemolytica can substitute functionally for the HlyA signal sequence. This 70 amino acid peptide contains little primary sequence similarity to the HlyA signal sequence, and we have hypothesized that these signal sequences assume a similar higher-order structure which is recognized by the HlyB/D transporter. In the present study, we have expressed and purified small peptides containing the C-terminal 61 amino acids of HlyA and the C-terminal 70 amino acids of LktA. We show that these signal peptides are sufficient for secretion from E. coli in a HlyB/D dependent manner. Circular dichroism analyses show that both molecules exhibit common biophysical properties. In aqueous solution, they appear to be mainly unstructured, but in a membrane mimetic environment they assume a helical secondary structure. The conformational change observed for both peptides going from an aqueous to a membrane mimetic environment may be an important feature of these signal sequences necessary for their recognition and transport.

Bacterial Proteins↗
PubMed1995

Activity of the MAP kinase ERK2 is controlled by a flexible surface loop.

BACKGROUND: The mitogen-activated protein (MAP) kinase, ERK2, is a tightly regulated enzyme in the ubiquitous Ras-activated protein kinase cascade. ERK2 is activated by phosphorylation at two sites, Y185 and T183, that lie in the phosphorylation lip at the mouth of the catalytic site. To ascertain the role of these two residues in securing the low-activity conformation of the enzymes we have carried out crystallographic analyses and assays of phosphorylation-site mutants of ERK2. RESULTS: The crystal structures of four mutants, T183E (threonine at residue 183 is replaced by glutamate), Y185E, Y185F and the double mutant T183E/Y185E, were determined. When T183 is replaced by glutamate, few conformational changes are observed. By contrast, when Y185 is replaced by glutamate, 19 residues become disordered, including the entire phosphorylation lip and an adjacent loop. The conservative substitution of phenylalanine for Y185 also induces relatively large conformational changes. A binding site for phosphotyrosine in the active enzyme is putatively identified on the basis of the high-resolution refinement of the structure of wild-type ERK2. CONCLUSIONS: The remarkable disorder observed throughout the phosphorylation lip when Y185 is mutated shows that the stability of the phosphorylation lip is rather low. Therefore, only modest amounts of binding energy will be required to dislodge the lip for phosphorylation, and it is likely that these residues will be involved in conformational changes associated with both with binding to kinases and phosphatases and with activation. Furthermore, the low-activity structure is specifically dependent on Y185, whereas there is no such dependency on T183. Both residues, however, participate in forming the active enzyme, contributing to its tight control.

Amino Acid Sequence↗
PubMed1995

CNTF or (-)-deprenyl in immature rats: survival of axotomized facial motoneurons and weight loss.

The application of ciliary neurotrophic factor (CNTF) to the cut ends of transected facial nerves in newborn rats has been reported to reduce the death of facial motoneurons (FMns) axotomized by the transection. Systemically delivered CNTF has been found to cause cachexia in adult mice. We compared the influence of dosage of CNTF and (-)-deprenyl on FMn death, weight loss, and animal survival in rat pups that underwent facial nerve transection at the 14th postnatal day (P14). CNTF was administered by osmotic mini-pumps connected to tubing ending either intrathecally or extrathecally near the craniocervical junction. CNTF caused weight loss and animal death that was similar to the cachexia reported in mice if administered in amounts of 1.1 microgram/day or greater. At the same doses, intrathecal CNTF was more effective than extrathecal CNTF in inducing the cachexia. (-)-Deprenyl did not alter animal survival or weight gain, even at high doses (10 mg/kg every 2 days). Intrathecal CNTF and intraperitoneal (-)-deprenyl, but not extrathecal CNTF, significantly increased the survival of the axotomized FMns. (-)-Deprenyl administered twice daily at 0.01 mg/kg was considerably more effective than CNTF in increasing FMn survival due to the limitation on CNTF dosage caused by the animal death.

Animals↗