Biomedical subjects

S Zhu

Publications and source records attributed to S Zhu.

At least 217 records · Page 12Linked to original sources

PubMed1997

Medical electronic link (MEL): providing telemedicine on the World Wide Web.

Many tertiary care centers in the USA have attempted to implement interactive television (IATV) or dynamic telemedicine systems. The advantage these systems provide is real-time interaction. The biggest disadvantage is cost: expensive hardware, band-width and personnel. An alternative to IATV is Medical Electronic Link (MEL); a low cost, store-forward, internet-based physician consultation system. MEL allows physicians in remote locations to consult physicians at the Dartmouth Hitchcock Medical Center in Lebanon, New Hampshire by using the World Wide Web. The Benefits of MEL are low hardware and band-width costs, accessibility, a self-explanatory interface, convenience, and its use of the case record. This system has been implemented at a family practice clinic in Manchester, NH and at the Tribhuvan University Teaching Hospital in Kathmandu, Nepal.

Computer Communication Networks↗

PubMed1997

[Pathological features of hepatocellular carcinoma carrying hepatitis C virus antigen].

OBJECTIVE: To analyze the pathological features of hepatocellular carcinomas (HCCs) carrying different hepatitis virus antigens histopathologically and systematically. METHODS: PAP and ABC kits were used in the immunohistochemical study, and CAS-200 System was applied in the image cytometry. RESULTS: As compared with HCCs carrying HBV marker(s), the HCCs carrying HCV marker showed more cases of clear cell type (7/9 vs 4/33), better differentiation of cancers, less necrosis of hepatocytes, milder lymphocyte infiltration in the hepatic sinuses or periportal areas (P < 0.01), higher incidence of bile ductule damages, and bore a close relation to the formation of lymphoid follicle in the surrounding tissues (P < 0.05). These patients were elder, with lower grade of symptoms and better prognosis after operation. CONCLUSION: HCCs carrying only HCAg have different pathological features and clinical characteristics from which carrying HBV marker(s). The results of image cytometry are in accordance with the biological behaviour of HCC.

Adult↗

PubMed1997

[Topographical evaluation of centration of excimer laser photorefractive keratectomy].

OBJECTIVE: To evaluate the situation of centrality of excimer laser photorefractive keratectomy (PRK). METHODS: Eyesys Corneal Analysis System was used for the computer-assisted analysis of corneal differential topographical maps gained preoperatively and 10 days postoperatively in 158 eyes of 98 patients with at least six months of follow-up to determine the direction and the distance of the center of ablation zone relative to the center of the entrance pupil, and a comparison in decentration difference was made between one-zone ablated eyes and multi-zone ablated eyes. RESULTS: Concerning the centration of ablated zone relative to the center of entrance pupil: 100 eyes (63.3%) were centered within 0.50 mm, 55 eyes (34.8%) were decentered more than 0.50 mm with 3 eyes (1.9%) being decentered more than 1 mm, and the mean decentration amount was 0.45 mm. 38 eyes were performed by multi-zone ablation and 120 eyes by one-zone ablation, their mean amount of decentration was 0.55 mm and 0.44 mm respectively, the difference being significant (P < 0.05). 4 eyes with decentration greater than 0.50 mm lost one to two lines of their best corrected visual acuity postoperatively due to the decentered ablation. CONCLUSION: Many factors contribute to decentration of the ablated zone. Great decentration will affect the recovery of the postoperative visual acuity. The Passive Eye Tracking System (PET) will contribute to precise centration and reduction of displacement.

Adolescent↗

PubMed1997

[The toxicity of gentamicin on corneal cells in culture].

OBJECTIVE: To determine the safe local concentration of gentamicin. METHODS: The authors studied the toxicity of gentamicin (no preservative) on 3 types of human corneal cell in culture with different concentrations. RESULTS: There was no toxic effect on the corneal epithelium, stroma and endothelium with gentamicin 1 mg. per milliliter in 48 h. in vitro, while the concentration was up to 2 mg. or 4 mg. per milliliter, all types of corneal cells appeared cytopathic effect (CPE), the toxicity of gentamicin to the corneal cells is in direct proportion to its concentration and time term of incubation, and the toxicity was the greatest on endothelium, slightest on stroma: CONCLUSION: It is suggested that the safe dosage of local concentration of gentamicin be 1 mg. per milliliter in human eyes.

Cells, Cultured↗

PubMed1997

Study on enzyme electrode biosensor of choline.

Choline oxidase was immobilized at a hydrogen peroxide electrode and the enzyme electrode was used for the amperometric determination of choline. The linear range is 0-200 mg/L with a response time of 40 seconds and a 25-microliter sample injection. The relative standard deviation (RSD) is less than 1.5% in 20 assays. The enzyme membrane can be used continuously at 25 degrees C for 60 days. The recovery rate of this method is 100.3-102.3%.

Alcohol Oxidoreductases↗

PubMed1997

Immunomodulatory role of opioids in the central nervous system.

Endogenous opioid peptides play a variety of roles in the central nervous system (CNS) from development to immune modulation. These functions are mediated mostly via specific opioid receptors uniquely localized in different brain regions and cells. Exogenous opioids can influence and modulate neuronal and glial cell function via an opioid receptor mediated mechanism, leading to either protection or damage of the brain. Mechanisms underlying CNS opioid effects may be mediated via immune mediators, such as cytokines, beta-chemokines, and free radicals (i.e. reactive oxygen intermediates (ROI) and nitric oxide (NO)) produced by activated glial cells (microglia and astrocytes). In the pathogenesis of HIV-1 infection in drug addicts, opiates such as morphine have been postulated to promote the progression of this virus and the development of secondary opportunistic infections. Kappa opioid receptor (KOR) ligands, on the other hand, may play a neuroprotective role. Differences in species, age, sex, cell culture system, stimuli, opioid administration route, concentrations used, strain of infectious agents, and treatment regimes have contributed to many conflicting results in the field of opioid research. More studies are needed to delineate how opioids exert their effects on glial cells as well as neurons with the goal of finding new therapeutic approaches for neurodegenerative diseases, such as AIDS dementia.

Adjuvants, Immunologic↗

PubMed1997

Magnesium status and risk of coronary artery disease in rural and urban populations with variable magnesium consumption.

This survey was conducted to determine the association between amount of magnesium intake and prevalence of coronary artery disease (CAD) and coronary risk factors in north India. There were 3575 subjects aged 25-64 years including 1769 rural (894 men, 875 women) and 1806 urban (904 men, 902 women) subjects. The survey methods were questionnaires for 7-day food intake record, physical examination and electrocardiography using World Health Organization criteria. The overall prevalence of CAD was three-fold greater in urban compared to rural subjects (9.0 vs 3.3 per cent, p < 0.001). The prevalence of CAD was significantly higher among subjects consuming lower dietary magnesium. Lower magnesium status was inversely associated with risk of CAD in both rural and urban subjects in both sexes. Among subjects with low magnesium status, there was a higher prevalence of hypertension, hypercholesterolemia and diabetes mellitus showing a significant increasing trend with decrease in magnesium status. Multivariate logistic regression analysis after pooling of data from rural and urban subjects and after adjustment of age showed that magnesium intake had an inverse association with prevalence of CAD. Serum magnesium (odds ratio: men 1.14, women 1.05), dietary magnesium (men 1.21, women 1.12), serum cholesterol (men 1.15, women 1.15), blood pressure (1.26 men, women 1.21), diabetes mellitus (men 1.20, women 1.18) in both sexes and smoking in men (1.05) were significant risk factors of CAD. Lower consumption of dietary magnesium and low serum Mg level in north India have a higher prevalence of CAD and of the coronary risk factors hypertension, hypercholesterolemia and diabetes mellitus. It is possible that increased intake of magnesium to about 500 mg/day may be of benefit in the prevention of CAD.

Adult↗

PubMed1997

Transfer of a branch of the anterior interosseus nerve to the motor branch of the median nerve and ulnar nerve.

OBJECTIVE: To explore the applied microsurgical anatomy of the intrinsic hand muscles and related nerves after nerve injuries in the wrist region and to report the results of new technique for the restoration of motor functions of the injured nerves. METHODS: Seven fresh forearm amputation specimens were employed for studying the anatomical and microsurgical characteristics of the relevant tissues. Transfer of the pronator quadratus branch of the anterior interosseous nerve (PBAN) to the recurrent branch of the median nerve (RBMN) and the deep branch of the ulnar nerve (DBUN) to restore the functions of the intrinsic hand muscles was performed on 20 patients from April 1979 to January 1994. Fourteen patients were followed up for 3-9 years with an average of 5 years and 8 months. RESULTS: The RBMN, DBUN and PBAN had approximately the same lengths of diameter and similar amounts of fascicles and nerve fibers so that after nerve transfer, the possibilities of misdirected connections were greatly reduced. In the latest follow-up, normal muscle strength was regained in 3 patients, grade VI strength in 6, grade III strength in 3 and grade II strength in 2. CONCLUSION: This new technique is able to restore the intrinsic hand muscular functions after median or ulnar nerve injuries in the wrist region or distal forearm.

Adolescent↗

PubMed1997

[Changes of concentrations of umbilical blood monoamines in low birth weight infant and their clinical significance].

OBJECTIVE: To investigate the changes of concentrations of umbilical blood monoamines in low birth weight (LBW) infants and their clinical significance. METHODS: By fluorescence spectrophotometry, the concentrations of umbilical plasma norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in 18 LBW before and after delivery were measured and compared with 20 normal birth weight (NBW) infants. RESULTS: The concentration of all monoamines, especially of the 2 catecholamines, i.e. NE and DA, were markedly lower in LBW than that in NBW (P < 0.05-0.01), regardless of prepartus or postpartus; the concentrations of all monoamines in postpartal umbilical plasma in both of LBW and NBW were higher than those in prepartal, and the increase of NE in NBW showed significant difference (P < 0.05). CONCLUSIONS: The decrease of all monoamines, especially of catecholamines in LBW could be one of the reasons causing the increase of mortality and the decrease of mental and physical development in LBW.

Dopamine↗

PubMed1997

[Genetic analysis of familial hypertension].

In order to study the genetic mode of familial hepertension, 63 pedigreses, including 140 nuclear pedigrees, of familial hypertension were investigated by means of pedigreed analysis and segregative analysis. Pedigreed analysis revealed that there is an evident phenomenon of vertical transmission in familial hypertension. It is hypothesed that there is a segregative ratio of dominant inheritance in A x U and A x A marital types, which is supported by segregative analysis. The data obtained suggest that the familial hypertension is an autosomal dominant hereditary disease. It is suggested that the genetic modes of familial hypertension could be different according to the different marital types of the patients. This finding suggests that the disease has a genetic heterogeneity. The research results will provide the reference evidence for the prevention, treatment and diagnosis of familial hypertension.

Adolescent↗

PubMed1997

[Studies on teratogenic effects of aluminum on intra uterine fetal development in mice].

Effects of oral administration of different doses of aluminum during pregnancy on intra uterine fetal development in mice were studied with experimental teratological methods. Results showed that over-intake of aluminum could lead obvious teratogenic and toxic effects on fetal development in mice. It could cause formation of encephalocele and dysostosis, intra uterine fetal growth retardation, and increase of embryo death rate, with a obvious dose-dependent relation. It suggests that excessive ingestion of aluminum may be one of the risk factors contributing to congenital neural tube defects, intra uterine fetal growth retardation and perinatal deaths.

Aluminum↗

PubMed1997

[Study of the relationship between the control of environmental microorganism and infection of patients with leukemia after trasplantation of bone marrow].

After the transplantation of bone marrow, patients with leukemia are easily infected by kinds of microorganism and die. In this paper, F-mice with the 60Co-gamma irradiation (maximum lethal dose) were transplanted bone marrow, then control the microorganism in the environment. Morever the laminar flow wards for the leukemia patient of bone marrow transplantation were designed according to the data combined with the clinic condition. There is no any infection in twelve patients with bone marrow transplantation from 1989 to 1993.

Animals↗

PubMed1997

[Clinical use of bilateral cervico-thoracic skin flaps].

In order to study the clinical efficacy of bilateral cervico-thoracic skin flap on repairing the contracture of the burn scar of the neck, 66 flaps were used in 33 patients from 1983 to 1995. The size of the flap ranged from 5 cm x 6 cm to 8.5 cm x 15 cm. The donor site was covered with split skin graft. The ratio between the length and the width of the flaps should not exceed 3:1. Fifty-nine flaps survived completely, but 7 had necrosis of small area which was healed without any influence on the function and appearance. The operative technique of the bilateral cervico-thoracic skin flaps were reported. The advantages of this type of skin flap and its applied anatomy and the postoperative care were discussed. In the repair of the cicatritial contracture deformity of the neck, it was important to define whether the skin defect was located in the submandibular, anterior cervical or anterior thoracic region, thus appropriate type of repair could then be given accordingly.

Adolescent↗

PubMed1997

[Anatomical study and clinical application of transfer of pronator quadratus branch of anterior interosseous nerve in the repair of thenar branch of median nerve and deep branch of ulnar nerve].

In order to obtain the anatomical basis of transferring the anterior interosseous nerve to repair the injury of thenar or ulnar nerve at the wrist level, ten fresh cadaveric forearms were dissected. The pronator quadratus branch of the median nerve was (1.5 +/- 0.4) mm in diameter with (866 +/- 144) nerve fibers. The recurrent branch of median nerve was (1.7 +/- 0.3) mm in diameter with (1,120 +/- 97) nerve fibers. The deep branch of ulnar nerve was (2.1 +/- 0.4) mm in diameter with (1,318 +/- 120) nerve fibers. To repair the thenar recurrent branch, nerve graft should be used to bridge between the distal end of the anterior interosseous nerve and the origination of the recurrent branch. The deep branch of the ulnar nerve could be repaired by direct suture after being dissected proximally. In patients, the technique was applied to repair 17 cases of injury of thenar branch and 3 cases of injury of deep branch of ulnar nerve. Among them, seventeen cases were followed up from 2 to 7 years. On electromyogram it was normal in 10. The myodynamia was restored in different degree: M2 in 2, M3 in 5, M4 in 7, M5 in 3. The procedure of the operation and the matters needed attention during the operation were discussed.

Adolescent↗

PubMed1996

Identification of nitration sites on surfactant protein A by tandem electrospray mass spectrometry.

Previous studies have shown that exposure of human surfactant protein A (SP-A) to nitrating agents [peroxynitrite (ONOO-); tetranitromethane (TNM; pH 8)] leads to nitrotyrosine formation. However, specific sites of nitration have not been identified. Herein, human SP-A, dissolved in Hepes buffer, was incubated with two boluses each of 0.5 mM ONOO- (pH 7.4) or 0.5 mM TNM (pH 8.0) for 15 min. After 30 min, SP-A samples were reduced, alkylated, and trypsin digested. The nitrated peptides and sites of amino acid nitration on the protein were identified by capillary high-performance liquid chromatography-coupled electrospray ionization tandem mass spectrometry (LC-ESMS/MS). The major nitrated peptide on both TNM- and (ONOO-)-exposed SP-A was the tryptic fragment Tyr161-Arg179 (YNTYAYVGLTEGPSPGDFR), located in the SP-A carbohydrate recognition domain. Sequencing of this nitrated peptide by LC-ESMS/MS demonstrated that the nitration was equally distributed on Tyr164 and Tyr166. A second lesser nitrated peptide corresponding to tryptic fragment Asn217-Arg222 (NCLYSR) was also found on TNM- and (ONOO-)-modified SP-A. No other nitrated amino acid was detected. Nitrated SP-A exhibited decreased ability to aggregate surfactant lipids in the presence of Ca2+. These data demonstrate that nitration of a specific tyrosine decreased an important protein function.

Amino Acid Sequence↗

PubMed1996

Histidyl-tRNA synthetase-related sequences in GCN2 protein kinase regulate in vitro phosphorylation of eIF-2.

In yeast, starvation for amino acids stimulates GCN2 phosphorylation of the alpha subunit of eukaryotic initiation factor-2 (eIF-2). Phosphorylation of eIF-2alpha induces the translational expression of GCN4, a transcriptional activator of the general amino acid control pathway. It has been proposed that GCN2 sequences containing homology to histidyl-tRNA synthetases (HisRS) bind uncharged tRNA that accumulate during amino acid limitation and stimulate the activity of GCN2 kinase. In this report we address whether the HisRS-related sequences are required for GCN2 phosphorylation of eIF-2alpha in an in vitro assay. To measure the activity of GCN2 kinase in cellular extracts, we expressed and purified a truncated form of yeast eIF-2alpha. Phosphorylation of the recombinant eIF-2alpha substrate was dependent on both GCN2 kinase activity and the eIF-2alpha phosphorylation site, serine 51. Mutations in the HisRS-related domain of GCN2, which have been shown to block phosphorylation of eIF-2alpha in vivo and the subsequent stimulation of the general control pathway, also greatly reduced eIF-2alpha phosphorylation in the in vitro assay. These results indicate that the HisRS-related sequences are required for activation of GCN2 kinase function.

Eukaryotic Initiation Factor-2↗

PubMed1996

Targeted disruption of guanosine diphosphate-dissociation inhibitor for Rho-related proteins, GDID4: normal hematopoietic differentiation but subtle defect in superoxide production by macrophages derived from in vitro embryonal stem cell differentiation.

The Rho subfamily of small guanosine triphosphate (GTP)-binding proteins, through their role in cytoskeletal organization, is involved in diverse cellular functions, including cell motility and morphologic changes during differentiation. Rac also has a special role in the production of superoxide, a key component in phagocytic antimicrobial function. Guanosine diphosphate (GDP)-dissociation inhibitors (GDIs) belong to one of three classes of proteins that regulate the critical cycling of GTP-binding proteins between the inactive and active states. Two homologous GDIs for the Rho subfamily have been identified. GDID4 is preferentially expressed in hematopoietic cells, while RhoGDI is ubiquitously expressed. Whether different physiologic functions are subserved by the two GDIs is unknown. We have derived embryonal stem (ES) cells with targeted disruption of both alleles of the GDID4 gene and examined hematopoiesis and phagocytic functions of macrophages derived from in vitro ES-cell differentiation. GDID4-/- ES cells develop like wild-type cells into colonies that contain heterogeneous populations of progenitor cells and differentiated erythromyeloid cells. GDID4-/- cells express no GDID4 protein, but have normal levels of RhoGDI. GDID4-/- macrophages phagocytose yeasts and antibody-opsonized erythrocytes as effectively as wild-type macrophages. However, a slight but consistent reduction in their capacity to generate superoxide was observed, which suggests new insight into the cellular role of GDID4. The minimal phenotypic effect of a loss of function of GDID4 also indicates a significant redundancy of function between GDID4 and RhoGDI. Their functional repertoire may be better revealed by a disruption of both genes. The use of hematopoietic cells derived in vitro from genotypically altered ES cells avoids the difficulties inherent in generating knockout animals and is a useful complementary approach for evaluating the gene function.

Animals↗

PubMed1996

Nitration of surfactant protein A (SP-A) tyrosine residues results in decreased mannose binding ability.

Nitric oxide (.NO) is a signal transducing free radical which can modify oxidant stress by limiting superoxide (O2.-)-mediated injury. However, the product of .NO reaction with O2.-, peroxynitrite (ONOO-), is a potent oxidizing and nitrating agent. Exposure of a mixture containing phosphatidylcholine liposomes and surfactant apoprotein A (SP-A; 10% by weight) to increasing concentrations of .NO, generated by spermine NONOate, and constant O2.- levels, produced by the action of xanthine oxidase on lumazine, suppressed O2.(-)-induced lipid peroxidation in the presence of Fe3(+)- EDTA. On the other hand, an increase in the .NO/O2.- value resulted in nitration of SP-A tyrosine residues, located in the carbohydrate recognition domain (CRD), and decreased the ability of SP-A to aggregate lipids and bind mannose, two functions that require an intact CRD. SP-A was also nitrated to a large extent following exposure to 3-morpholinosydnonimine (SIN-1) or tetranitromethane at pH 8. In each case, increased nitrotyrosine content correlated in a monotonic fashion with inhibition of lipid aggregation and mannose binding, correlated with the extent of functional inhibition. Superoxide dismutase (2400 U/ml) and urate (100 microM; nonspecific scavenger of both ONOO- and hydroxyl radical), but not mannitol (50 mM; hydroxyl radical scavenger), prevented the SIN-1-induced injury to SP-A. In contrast, spermine NON-Oate or xanthine oxidase plus lumazine alone neither inhibited SP-A function nor nitrated the protein. These results indicate that at high concentrations, .NO inhibit O2.-induced lipid peroxidation. However, ONOO., formed by the reaction of .NO and O2.-, nitrates SP-A leading to decreased ability to aggregate lipids and bind mannose.

Animals↗