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Biomedical subjects

Y S Zhang

Publications and source records attributed to Y S Zhang.

At least 19 recordsLinked to original sources
PubMed1995

Expression of hepatic metallothionein messenger RNA in feral and caged fish species correlates with muscle mercury levels.

Metallothioneins (MTs) are low-molecular-weight cytosolic proteins that are induced by cellular stress as well as exposure to various heavy metals including mercury. Excessive residues of mercury have recently been identified in various fish species of the lower Ouachita River system in Arkansas. Fillets of mature largemouth bass (Micropterus salmoides) collected from Woodard Lake, an ox-bow lake of the Ouachita River, possessed muscle residues of mercury ranging from 0.3 to 1.0 ppm (micrograms/g). To assess the usefulness of using MT expression as a biomarker of mercury exposure, livers and fillets were obtained from feral bass of Woodard Lake. Ouachita served as a control site having mercury residues below detection. Analyses using a ribonuclease protection assay with winter flounder MT cDNA revealed that bass had significantly elevated levels of MT mRNA which correlated (r2 = 0.756) with the levels of mercury in muscle fillets. To further explore the water quality of Woodard Lake, 10 juvenile channel catfish were housed in cages and placed where feral collections were made in both sites for 2 weeks. Mercury was not detected in muscle or liver and no significant difference in hepatic MT mRNA was observed. These data demonstrate that MT mRNA expression can be used as a tool to assess exposure to heavy metals and suggest that the elevated levels of mercury in large predatory fish may be due to trophic magnification rather than a single point-source exposure.

Animals↗
PubMed1995

Recombinant A17 Lys human insulin: purification and characterization.

Recombinant A17 Lys human insulin precursor expressed in yeast cells was isolated from the culture medium. After purification, the precursor was converted into A17 Lys human insulin. A17 Lys human insulin can be crystallized but has much lower receptor-binding and biological activities than porcine or human insulin where A17 is Glu. It is proposed that the A17 Glu residue may be involved in the receptor-binding or the active site of human insulin.

Amino Acids↗
PubMed1994

Effect of the extracts of pumpkin seeds on the urodynamics of rabbits: an experimental study.

Pumpkin seeds were prepared into oil n-butyle alcohol and ether extracts. The effects of the three extracts on the urodynamics of rabbits were observed. It was concluded that the oil preparation could remarkably reduce the bladder pressure, increase the bladder compliance, reduce the urethral pressure. Other two kinds of preparations had no effect in this experimental. The mechanisms of the effect of oil preparation on the urodynamics and the prospect of clinical use was discussed.

Animals↗
PubMed1992

Inhibitory effect of fluoride on renal stone formation in rats.

The effect of fluorine (F) on stone formation induced by ethylene glycol (EG) was studied in rats. For different groups, the drinking water was supplemented with EG, sodium fluoride (NaF), EG+NaF, or nothing as control. An isotope-tracing method was used to evaluate experimental stone formation in the kidneys by introducing 45Ca intraperitoneally into rats and then measuring the radioactivity of the kidney. At the end of the 4-week experiment, rats of the EG+NaF group showed a significantly lower incidence of gross urinary stones and lower 45Ca activity in their kidneys compared to the EG group of rats. Both the EG group and EG+NaF group had markedly increased urinary oxalate excretion, with the latter significantly lower than the former (p less than 0.05). Urinary oxalate excretion was relatively lower in the NaF group than in the control group. This study indicates that NaF can inhibit renal stone formation induced by EG by decreasing oxalate synthesis and urinary oxalate excretion, and suggests a possible clinical therapeutic value of NaF in the prevention of oxalate kidney stones.

Animals↗
PubMed1991

Initial purification and characterization of hepatic microsomal cytochrome P-450 from BNF-treated perch (Perca fluviatilis).

1. A procedure was developed for isolating and purifying cytochrome P-450 from hepatic microsomes of BNF-treated perch, using modified versions of the methods of Williams and Buhler (1982. Biochim. biophys. Acta 717, 398-404) and Goksøyr (1985. Biochim. biophys. Acta 850, 409-417). 2. Following chromatography on phenyl-Sepharose CL 4B and DEAE-Sepharose CL-6B, the major peaks, fractions b and c, were resolved into five fractions, possibly representing different isoenzymes, by a FPLC with a strong anion exchange column (Mono Q). 3. These fractions have been characterized on the basis of their spectral, electrophoretic and immunological properties. 4. The purified form of cytochrome P-450 in fraction V from perch liver showed a number of similarities to cytochrome P-450c, the major BNF-inducible cytochrome P-450 in cod liver. 5. Therefore we suggest that this purified form of cytochrome P-450 is a BNF-induced form in perch and that it is closely related to the gene subfamily cytochrome P-450 IA1.

Animals↗
PubMed1991

Clinical disease, drug susceptibility, and biochemical patterns of the unnamed third biovariant complex of Mycobacterium fortuitum.

Previous studies of Mycobacterium fortuitum identified isolates that did not fit its two recognized biovariants. Eighty-five clinical isolates of this group, the "third biovariant complex", were evaluated. They represented 16% of 410 isolates of M. fortuitum submitted to a Texas laboratory and 22% of 45 isolates in Queensland, Australia. Most infections (76%) involved skin, soft tissue, or bone and occurred after metal puncture wounds or open fractures. Isolates differed from biovar fortuitum in resistance to pipemidic acid and use of mannitol and inositol as carbon sources. Two subgroups were present, and examples were deposited in the American Type Culture Collection. Isolates were resistant to doxycycline and one-third were resistant to cefoxitin. All were susceptible to amikacin, ciprofloxacin, sulfamethoxazole, and imipenem. Surgical debridement combined with drug therapy based on in vitro susceptibilities resulted in cures of cutaneous disease or osteomyelitis. DNA homology studies are needed to determine the taxonomic status of these organisms.

Bacterial Typing Techniques↗
PubMed1991

Nosocomial outbreak of respiratory tract colonization with Mycobacterium fortuitum: demonstration of the usefulness of pulsed-field gel electrophoresis in an epidemiologic investigation.

Between August 1989 and January 1990, 16 patients on an alcoholism rehabilitation ward (ARW) developed positive sputum cultures for Mycobacterium fortuitum. During a 2-wk surveillance period, six of 43 ARW patients but none of 20 staff members had positive sputum cultures. In addition, none of 54 patients and staff on an adjacent ward sharing the same ice machine and water supply had positive cultures, and none of 92 acid-fast bacilli cultures performed on all sputum specimens from all other inpatient sources during the same 2-wk period were positive. The only exposure factor common to all cases was the use of one or both of the ward showers. Compared with 36 ARW control patients, cases were more likely to report clinical criteria for chronic bronchitis (odds ratio, 6.6; 95% confidence interval, 1.5 to 28.6; p = 0.02). Using phenotype analysis, plasmid profiles, and pulsed-field gel electrophoresis of large genomic DNA restriction enzyme fragments, the 16 case isolates were found to be identical. This strain of M. fortuitum was also cultured from a tap connected to the water line supplying the ARW showers, but not from the showers themselves. No further cases were identified after the showers were disconnected and decontaminated. To our knowledge, this is the first clinical use of pulsed-field gel electrophoresis for genetic comparison of mycobacterial strains. It demonstrates the important potential of this technique for studying the epidemiology of mycobacterial infections. Showers should be considered a possible source of nosocomial respiratory tract colonization with M. fortuitum.

Case-Control Studies↗
PubMed1991

[Studies on water soluble polysaccharides isolated from Tribulus terrestris L--purification and preliminary structural determination of heteropolysaccharide H].

Crude polysaccharides extracted from the stem and leaf of Tribulus terristris L after the removal of crude saponins are a mixture of heteropolysaccharides composed of Ara, Rha, Xyl, GalA, Gal, Glc and Man in molar ratios of 6.0:2.1:1:3.6:3.4:7.7:2.9. A homogeneous polysaccharide H obtained by gradation and purification contains Ara, Rha, Xyl, GalA. Gal and Glc. in molar ratios of 1.6:2.4:0.1:3.5:1.3:1. Its molecular weight was found to be 1 x 10(5). By means of pectinase and beta-D-galactosidase enzymolysis, periodate oxidation, Smith degradation, partial hydrolysis with acid, methylation, GC and GC-MS, the H contains alpha-D-GalA (1-4) and L-Rha (1-2) probably linked alternately as main chain with some L-Rha (1-2) side chains.

Drugs, Chinese Herbal↗
PubMed1991

[Role of the nucleus vestibularis medialis in vestibulo-sympathetic response in rats].

Experiments were performed on rats anesthetized with alpha-chloralose and urethane. The sympathetic response evoked by stimulation of the vestibular nerve root at its entrance to brain-stem was recorded from the ipsi-splanchnic nerve. Electrical stimulation of the vestibular nerve elecited a distinct averaged response in the ipsilateral splanchnic nerve. The mean latency of response was 45.8 +/- 6.98 ms with a duration of 55.21 +/- 5.35 ms. With increasing the strength of stimulation, the amplitude of response was increased, but the latency was unchanged. By monitoring the lamellar field potentials in NVM and choosing the locus of phase-reversal of field potential as the stimulating site, an averaged response in ipsi-splanchnic nerve with a latency of 32 ms was obtained, while the recorded splanchnic nerve response had a latency of 43 ms, when the vestibular nerve was stimulated. After electrolytic lesion of the rostral part of ipsi-NVM, the vestibulo-sympathetic response was significantly reduced. When a second lesion was placed in the caudal NVM, the response disappeared. Lesion in Deiters' nucleus had no effect on the vestibulo-sympathetic response. The results suggest that NVM is a critical relay station in vestibulo-sympathetic response recorded in the splanchnic nerve.

Animals↗
PubMed1990

Cefotaxime-resistant Nocardia asteroides strains are isolates of the controversial species Nocardia farcinica.

A recent study of Nocardia asteroides revealed that 95% of clinical strains had one of five antibiotic resistance patterns. We found the pattern of resistance to cefotaxime and cefamandole in 19% of 200 clinical N. asteroides isolates. Isolates with this drug resistance pattern were from numerous geographic sources and were associated with significant clinical disease (56% of patients had disseminated infections). Phenotypic studies revealed that these isolates were relatively homogeneous and matched previous descriptions and reference strains of the controversial species N. farcinica. Growth at 45 degrees C, acid production from rhamnose, ability to utilize acetamide as a nitrogen and carbon source, and resistance to tobramycin and cefamandole were features of N. farcinica that could be tested in the clinical laboratory and allowed their distinction from N. asteroides. The serious nature of disease due to N. farcinica and its resistance to the newer cephalosporins suggest a clinical need for laboratory identification of this species. (Current tests used in clinical laboratories do not distinguish N. farcinica from N. asteroides.) This is the first recognition that N. farcinica has a specific drug resistance pattern and confirms the previously described concept that drug resistance patterns of N. asteroides may be associated with specific taxonomic groups.

Cefotaxime↗
PubMed1990

Preliminary crystallographic analysis of deshexapeptide (B25-B30) insulin.

Satisfactory single crystals of deshexapeptide (B25-B30) insulin for X-ray crystal structure analysis have been grown in citrate buffer by the method of hanging-drop gas phase diffusion. The crystal belongs to the monoclinic system with space group C2. The unit cell constants are a = 42.6 A, b = 37.9 A, c = 27.2 A, beta = 125.4 degrees and there is only one molecule of deshexapeptide insulin in an asymmetric unit.

Crystallography↗
PubMed1989

Antimutagenic effect of garlic (Allium sativum L.) on 4NQO-induced mutagenesis in Escherichia coli WP2.

Aqueous extract prepared from garlic bulbs markedly suppressed the mutagenesis in both E. coli WP2 trp- and E. coli WP2 trp- uvrA- induced by 4-nitroquinoline 1-oxide (4NQO), but not that induced by UV. Cellular toxicity, inhibition of the expression of the Trp+ phenotype and delay of the first cell division after 4NQO treatment were not observed in the presence of the extract. Since the extract showed identical antimutagenic effects against 4NQO in both test strains but no effect on the mutagenesis of UV, it seems that the extract might act by inactivating the electrophilic group(s) of 4NQO or inhibiting its metabolic activation.

4-Nitroquinoline-1-oxide↗
PubMed1989

Primary structure of two neuropeptide hormones with adipokinetic and hypotrehalosemic activity isolated from the corpora cardiaca of horse flies (Diptera).

The primary structures of two neuropeptides, Tabanus atratus adipokinetic hormone (Taa-AKH) and Tabanus atratus hypotrehalosemic hormone (Taa-HoTH), from the corpora cardiaca of horse flies (Diptera: Tabanidae) have been determined. Amino acid sequences of Taa-AKH (less than Glu-Leu-Thr-Phe-Thr-Pro-Gly-Trp-NH2) and Taa-HoTH (less than Glu-Leu-Thr-Phe-Thr-Pro-Gly-Trp-Gly-Tyr-NH2) (where less than Glu = pyroglutamic acid) were determined by automated gas-phase Edman degradation of the peptides deblocked by pyroglutamate aminopeptidase and by fast atom bombardment mass spectrometry. The hormones were synthesized, and the natural and synthetic peptides exhibited identical chromatographic, spectroscopic, and biological properties. When assayed in adult face fly males, Taa-AKH and Taa-HoTH demonstrated hyperlipemic activity, in addition, Taa-HoTH also demonstrated a significant hypotrehalosemic activity.

Amino Acid Sequence↗
PubMed1989

Structure and activity of the B-chain of insulin.

Despentapeptide (B26-30)-insulinamide (B25) prepared by a semisynthetic procedure was found to have about 65% of the hypoglycaemic activity of natural insulin. In contrast, the binding of the modified insulin analogue to insulin specific receptors was markedly increased. The discrepancy between the loss of biological potency and the apparent increase in binding affinity for membrane receptors reveals that not all of the biological activity of insulin is regulated by the receptor-binding system. The tetrapeptidamide of the B-chain of insulin (Arg-Gly-Phe-Phe-NH2) was clearly shown to have both insulin-like and insulin-potentiating actions in vivo although it had no effect on insulin receptor function in vitro. Evidence suggests that the small peptide fragment of insulin may be internalized and acts at the post-binding site(s) of the glucose metabolic pathway in target tissues. The present data support the general concept that insulin may exert its complex molecular actions through internalized hormonal fragment as well as the transmembrane mediators generated from receptor binding.

Adipose Tissue↗
PubMed1989

[Tuberculous meningitis with hydrocephalus: a clinical and CT study].

Fourteen cases of tuberculous meningitis complicated by moderate or severe hydrocephalus identified by CT are reported. The accumulation and blockage of tuberculous exudate in the basic cisterns and ependymitis in the cerebrospinal drainage pathway are the important pathological features of this disease. There may be a correlation of hydrocephalus with hyponatraemia. Headache, vomiting, and impaired consciousness are common symptoms, although a few cases did not show obvious symptoms of raised intracranial tension. The study suggests a relation between the degree of hydrocephalus and the pressure on lumber puncture. If patients with impaired consciousness, especially in the chronic stage show no improvement during medical treatment, ventricular shunt may bring about remarkable improvement.

Adolescent↗
PubMed1989

[Investigation on the composition and structure of 400 urinary calculi].

400 urinary calculi have been analyzed by chemical and physical methods, namely chemical qualitative analysis, metallic elements spectrometry, X-ray diffraction, infrared spectroscopy, thermographimetric analysis, polarizing microscopy, scanning electron microscopy, etc. Further understanding of the correlation between the structure and the composition of calculi was achieved, which may be helpful in inquiring the formation of urinary calculi.

Calcium↗
PubMed1988

Isolation and primary structure of a neuropeptide hormone from Heliothis zea with hypertrehalosemic and adipokinetic activities.

A neuropeptide was isolated from the corpora cardiaca of the corn earworm moth Heliothis zea, and purified by sequential gradient elution in three reversed phase-high performance liquid chromatographic steps. The primary structure, pGlu-Leu-Thr-Phe-Ser-Ser-Gly-Trp-Gly-Asn-NH2 was determined by automated gas-phase Edman degradation of the peptide deblocked with pyroglutamate aminopeptidase, and confirmed by fast atom bombardment mass spectrometry. The hormone was synthesized and the natural and synthetic peptides had identical chromatographic and spectroscopic properties. Both natural and synthetic hormones caused the elevation of trehalose and lipid levels in the hemolymph of adult H. zea males.

Amino Acid Sequence↗