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Biomedical subjects

W Wu

Publications and source records attributed to W Wu.

At least 415 records · Page 23Linked to original sources
PubMed1994

Disruption of fast axonal transport in vivo leads to alterations in Schwann cell gene expression.

Following nerve injury, Schwann cells distal to the site of injury down-regulate genes associated with myelination. We hypothesized that at least some of these alterations were due to the loss of ongoing axon:Schwann cell homeostatic signals, as opposed to loss of physical contact and/or inflammatory responses. To directly test this hypothesis, we perturbed axonal physiology by selectively blocking fast axonal transport via locally cooling the sciatic nerve to 5-8 degrees C (a cold block). Immunostaining with the monoclonal antibody ED1, which recognizes mononuclear phagocytic cells, demonstrated that macrophages did not invade the cold-blocked nerve, indicating the lack of an inflammatory response. Morphological studies demonstrated that the nerve distal to the cold block showed no signs of Wallerian degeneration, with maintenance of normal axon and myelin profiles, and confirmed the absence of invading macrophages. Thus, any effects of a cold-block treatment were not likely due to inflammatory responses or to loss of physical contact between axons and Schwann cells. To determine whether this treatment affected Schwann cell phenotype, we examined expression of the major myelin protein P0, and p75 NGF receptor, both of which are regulated as a function of axon:Schwann cell interactions. Levels of p75 NGF receptor mRNA were unaffected by the cold block, while p75 NGF receptor protein levels were increased in the region of the nerve immediately adjacent to the cold block, presumably reflecting protein accumulation as a consequence of the block to fast axonal transport. In contrast, levels of P0 mRNA were decreased in the distal nerve in a fashion that indicated modulation of Schwann cell phenotype as a function of local axonal microenvironment. These data therefore suggest that P0 and p75 NGF receptor are regulated as a function of two different aspects of Schwann cell:axon communication. Furthermore, these data demonstrate that the presence of axon:Schwann cell contact alone is insufficient to maintain Po gene expression and indicate that at least some myelin-specific Schwann cell responses are dependent upon ongoing biochemical signals generated by the axon and maintained by fast axonal transport.

Animals↗
PubMed1994

Implantation of PNS graft inhibits the induction of neuronal nitric oxide synthase and enhances the survival of spinal motoneurons following root avulsion.

In a spinal root injury model, our previous studies have shown that induction of nitric oxide synthase (NOS) appears only in spinal motoneurons of the root-avulsed segment in which significant motoneuron loss occurs but not in those of the distal root-axotomized segment (root axotomy 5-10 mm from the spinal cord) in which most motoneurons survive the injury. One hypothesis for the different response of motoneurons to root avulsion and distal root axotomy is that neurotrophic factors produced by the remaining peripheral nervous system (PNS) component are available for the distally axotomized motoneurons but are not available following avulsion. This hypothesis is tested in the present study by implantation of a PNS graft following the root avulsion. Results of the present study show that implantation of a PNS graft significantly enhances the survival of motoneurons following avulsion. Expression of NOS due to avulsion injury is completely inhibited in all motoneurons that regrow into the PNS graft. These results indicate that induction of NOS in avulsed motoneurons may result from the deprivation of neurotrophic factors produced by the PNS component, and the survival promoting effects of neurotrophic factors may be achieved by modifying certain cellular molecules such as NOS.

Amino Acid Oxidoreductases↗
PubMed1994

Neuronal nitric oxide synthase is induced in spinal neurons by traumatic injury.

Nitric oxide appears to mediate the immune functions of macrophages, the influence of endothelial cells on blood vessel relaxation, and also to serve as a neurotransmitter in the central and peripheral nervous system. Macrophage nitric oxide synthase is inducible with massive increases in new nitric oxide synthase protein synthesis following immune stimulation of macrophages. By contrast, endothelial nitric oxide synthase and neuronal nitric oxide synthase are thought to be constitutive with activation induced by calcium entry into cells in the absence of new protein synthesis. Developmental studies showing the transient expression of neuronal nitric oxide synthase in embryonic and early postnatal life in rodent spinal motoneurons and cerebral cortical plate neurons (Bredt and Snyder, unpublished observations) implies inducibility of neuronal nitric oxide synthase. Moreover, neuronal nitric oxide synthase expression is greatly enhanced in sensory ganglia following peripheral axotomy. Staining for NADPH diaphorase in spinal motoneurons is greatly increased following ventral root avulsion. In many parts of the Central Nervous System NADPH diaphorase staining reflects nitric oxide synthase. In the present study, we have combined in situ hybridization for neuronal nitric oxide synthase, immunohistochemical staining of neuronal nitric oxide synthase, and NADPH diaphorase staining to establish that neuronal nitric oxide synthase expression is markedly augmented in spinal motoneurons following avulsion. The generality of this effect is evident from augmented staining in nucleus dorsalis following spinal cord transection.

Amino Acid Oxidoreductases↗
PubMed1994

Fabrication and characterization of glucose sensors based on a microarray H2O2 electrode.

A glucose sensor was recently developed by modifying an immobilized GOD (glucose oxidase) membrane and coating Nafion diffusion limiting membrane over an amperometric H2O2 MAE (microarray electrode), which was fabricated by using standard planar processing. The chip of the sensor is 2.5 mm by 15. The MAE is composed of an Ag/AgCl RE (reference electrode), a Pt CE (counter electrode) and two sets of Pt WE (working electrode), each set consists of five bands. Silicon nitride was chosen as the top insulator. Six MAEs different in both width and length of the band were examined and the MAE with the narrowest width (10 microns) of bands exhibits the best electrochemical performances. The glucose sensor based on the MAE B1-2 presents a linear range of 0.5-40 mM glucose at 37 degrees C with a 1/15 M phosphate buffer solution (pH = 7.0) as supporting electrolyte. The sensitivity, background current, response time, CV (coefficient of variation) and long-term stability of the sensor are 7.1 +/- 0.5 nA/mM, 2 +/- 0.5 nA, 30 s, 3.4% and 6 days respectively.

Biosensing Techniques↗
PubMed1994

Increased redness in turkey breast muscle induced by fusarial culture materials.

Short-term feeding trials with experimentally moldy rice (10% of diet) or corn (12.5%) were carried out on turkey poults to screen for toxigenic Fusarium, Penicillium, and Aspergillus, which were recovered from corn or commercial turkey feed. A major finding was that culture materials of some fusaria increased the redness of turkey breast muscle without causing obvious hemorrhages either in the musculature or in the internal organs. Corn culture but not rice culture of Fusarium moniliforme (M-1325) depressed body weight gains, feed utilization, and heart weights (P = .01). The increased redness (reddish discoloration) could lead to the depreciation of fresh turkey muscle product.

Animal Feed↗
PubMed1994

[16S rRNA reverse transcription-polymerase chain reaction of leptospires].

We amplified the leptospiral RNAs of Leptospira interrogans serovar lai strain Lai and L. biflexa serovar patoc strain Patoc I, extracted by the method of SiO2-high concentration salt solution (8 mol/L GuHCl) absorption, with the 16S rRNA gene primers of Leptospira interrogans by reverse transcription-polymerase chain reaction (RT-PCR). It demonstrated that the detecting sensitivity by naked eye after electrophoresis could be 100 times higher when we amplified DNA and RNA of leptospires at the same time by RT-PCR.

Base Sequence↗
PubMed1994

[Correction of severe epicanthus using the square-flap method].

The square-flap method has been adopted gradually in plastic surgery because of lengthening effectively the distance between two points on the skin surface. Good results have been obtained in the treatment of severe epicanthus in 14 cases of 26 eyes by using modified square flap since 1990. This paper describes the operation design, advantages and key points of the surgery.

Adolescent↗
PubMed1994

[Clinical observation on the treatment of 1,627 cases of schistosomiasis haematobia with praziquantel of different dosages].

A total of 1,627 cases of schistosomiasis haematobium had been treated with praziquantel of different dosages by the Chinese Medical Team in Mali. The patients were all confirmed by egg detection in urine examination and were divided into three groups. Group A, 1,187 cases, were each given a single dose of 40 mg/kg of praziquantel. In Group B, 321 cases, were each treated with 10 mg/kg of praziquantel, t.i.d. for two days. In Group C, 119 cases, were each administered with one dose of 50 mg/kg of praziquantel. Three months after treatment, the urine egg negative conversion rates were 88.5%, 96.6% and 89.1%, respectively. It was showed that Group B gave the best efficacy and produced fewer side effects, suggesting that the regime of praziquantel treatment given in divided doses is better than that given at a single dose.

Adolescent↗
PubMed1994

The effect of radix Salviae Miltiorrhizae Composita on peroxidation of low density lipoprotein due to copper dichloride.

It is well known that plasma lipoprotein, particularly oxidized LDL, plays an important role in the pathogenesis of atherosclerosis and atherosclerotic diseases. We used oxidized LDL generated by incubating LDL from healthy persons with copper dichloride as a model to investigate the antioxidate property of Radix Salviae Miltiorrhizae Composita (RSMC). On photos, the spot X1 and the spot X2 were clearly found in the control group after the dialysis into copper dichloride for 24 and 48 hours, but they could not found in the RSMC group. The analysis of the constituents of lipids in LDL (by charring method) showed that after dialysis the percentages of the spot X1 and the spot X2 in the RSMC group were significantly lower than those in the control group (P < 0.01). The results suggest that RSMC plays a potential role in antioxidation of lipids or LDL.

Adult↗
PubMed1994

[The causes of necrosis of arteriovenous flap and its modification].

Arteriovenous flaps have been developed for more than ten years, however the cause of necrosis of the flap remains obscure. We observed the changes in the microcirculation of the flap, and it was revealed that most of capillaries were occluded in the early arterialized stage, and the capillary patency was only 10%-20%. The latter was increased to 80%-90% three days later. All these changes were due to the damage of endothelial cells by arterial blood, because of high pressure and oxygen tension, resulting if cell swelling, fissuring, exfoliation and finally thrombosis. As a consequence, the effective microcirculation volume became decreased. As venous endothelial cells required time to adapt arterial blood, and expansion of skin could increase tissue capillaries in number, the arteriovenous flap was modified by skin expansion before arterialization. This method improved the survival rate remarkably.

Animals↗
PubMed1994

Experimental study on ischemia and reperfusion injury of rat liver and effects of ligustrazine and salvia compound.

The present study was to investigate changes of free radicals in the whole rat liver, changes of ATP levels of hepatic cells, ultrastructural changes in hepatic tissue during ischemia and reperfusion in rats and the effects of ligustrazine and salvia compound. The results indicated that: 1) the free radical levels increased by 8.3-fold and 9.0-fold in the groups with 30 and 60 min ischemia after 40 min reperfusion, as compared with the group with ischemia only (P < 0.01, P < 0.01, respectively). 2) The levels of ATP returned to normal in the group with 30 min ischemia after reperfusion for 40 min and 3 d, remained low in the group with 90 min ischemia and fell again after a mild increase in the group with 60 min ischemia. 3) The hepatic and endothelial cell damage after ischemia became more severe after reperfusion, as revealed by electron microscopy. The present study also showed that ligustrazine and salvia compound have protective effects against reperfusion injury. They can be used to scavenge free radicals, improve hepatic microcirculation and alleviate hepatic and endothelial cell damage.

Adenosine Triphosphate↗
PubMed1994

The effect of radix salviae miltiorrhizae composita and ligustrazine on lipid peroxidation in low density lipoprotein due to copper dichloride.

It is well known that lipid peroxide in low density lipoprotein (LDL) plays an important role in atherosclerosis and atherosclerotic diseases. We used oxidized LDL generated by incubating LDL from healthy persons with copper dichloride as a model to investigate the anti-lipid-peroxide property of Radix Salviae Miltiorrhizae Composita (RSMC) and ligustrazine. The changes in concentrations of lipid peroxide and lipids in LDL due to Cu++ were studied, and the effects of RSMC and ligustrazine on the changes were studied. The results in our study indicate that RSMC has a potential role on anti-lipid-peroxidation, but it was not found that ligustrazine has similar anti-peroxidation action.

Adult↗
PubMed1994

[Analysis on early serum samples from patients with leptospirosis by polymerase chain reaction].

Fifty-five serum samples from patients with leptospirosis treated by the method of high SiO2 concentration salt solution absorption were analysed with the variable sequences of the 16S rRNA genes of Leptospria interrogans as primers. It is shown that the 16S rRNA gene primer is useful for the clinical detection and the epidemic investigation of leptospirosis, and the detecting effect by PCR is superior to that by the blood culture and MAT (P < 0.01).

Genes, Bacterial↗
PubMed1994

Comparison of cardiac electrophysiologic effects of experimental hypothyroidism and chronic oral amiodarone administration in dogs.

A comparative study on ventricular electrophysiologic effects of experimental hypothyroidism and chronic oral amiodarone administration was made in canine models, with the application of electrical stimulation and monophasic action potential recording. The results showed similar effects possessed by hypothyroidism and amiodarone, which included prolongations in ventricular repolarization and refractoriness, an increase in ventricular fibrillation threshold, and a decrease in the incidence of reperfusion ventricular fibrillation. The differences were that hypothyroidism primarily lengthened phase 2 repolarization and had no effects on intraventricular conduction time, whereas amiodarone lengthened both phase 2 and phase 3 repolarization and suppressed myocardial conduction velocity.

Amiodarone↗
PubMed1994

The T alpha 1 alpha-tubulin promoter specifies gene expression as a function of neuronal growth and regeneration in transgenic mice.

We have previously demonstrated that one member of the alpha-tubulin multigene family, termed T alpha 1 in rats, is regulated as a function of neuronal growth and regeneration. To elucidate the molecular mechanisms responsible for coupling gene expression to morphological differentiation, we have isolated the T alpha 1 gene, have fused 1.1 kb of the 5' flanking region to a nuclear lacZ reporter gene, and have generated transgenic mice. Analysis of these transgenic mice demonstrated that marker gene expression was specific to the CNS and PNS, with expression in vivo at embryonic day 13.5 being similar to expression of the endogenous gene. Moreover, the induction of transgene expression was correlated temporally with neuronal commitment in developing neural crest-derived peripheral neurons and in the developing retina. Immunocytochemical analysis of mixed primary embryonic brain cultures confirmed that transgene expression was specific to neurons, with the majority of neurons, but not astrocytes or oligodendrocytes, expressing beta-galactosidase. Transgene expression in vivo was maintained in developing neurons until early in postnatal life, subsequent to which its expression decreased coincident with neuronal maturation. The transgene was then reinduced in regenerating facial motoneurons following unilateral axotomy of the facial nerve. Thus, 1.1 kb of 5' flanking sequence from the T alpha 1 gene contains the sequence elements responsible for specifying gene expression to embryonic neurons and for subsequently regulating gene expression in both developing and mature neurons as a function of morphological growth.

Animals↗
PubMed1994

Alterations of pulmonary gas exchange after superimposed carbon monoxide poisoning in acute lung injury.

BACKGROUND: Smoke inhalation injury produces substantial morbidity and mortality caused both by immediate catastrophic pulmonary failure and by the subsequent development of pneumonia. Although carbon monoxide (CO) poisoning is present to a degree in nearly all instances of smoke inhalation, the importance of CO in the pathogenesis of smoke inhalation injury remains controversial because smoke contains numerous other potential pulmonary toxins such as aldehydes, chlorine gas, and hydrochloric acid. This study was performed to determine whether CO poisoning acts as a cofactor in the evolution of inhalation injury. METHODS: Four groups of anesthetized dogs received ventilation with 1% CO in room air alone, intratracheal instillation of 2.0 ml/kg 0.1 N hydrochloric acid (HCl) alone, or acid either immediately or 30 minutes before CO. Ventilation/perfusion relationships were measured for 4 hours thereafter with the multiple inert gas elimination technique. RESULTS: Acid instillation established 30 minutes before CO poisoning resulted in significantly decreased carboxyhemoglobin concentrations after ventilation with 1% CO in air for 10 minutes. However, CO elimination was markedly delayed in both acid-challenged groups ventilated with CO. Moreover, acid instillation immediately before CO poisoning significantly exacerbated the development of ventilation/perfusion inequality caused by the acid, because the development of shunt was accelerated. CONCLUSIONS: CO poisoning is an important cofactor in the development of inhalation injury by acceleration of the development of ventilation/perfusion inequality after inhalation.

Animals↗
PubMed1993

Pre-pro-somatostatin mRNA in the developing rat spinal cord with special reference to ventral horn motoneurons.

The expression of pre-pro-somatostatin (ppSOM) mRNA in the spinal cord of the developing rat was determined by in situ hybridization. Expression of ppSOM mRNA was detected in cells in the gray matter of the dorsal and ventral horns at day E15, the earliest stage examined in this study. Expression of ppSOM mRNA persisted during development and into adulthood in the dorsal horn. In contrast, ppSOM mRNA expression in presumptive ventral horn motoneurons was apparent during pre- and perinatal periods, but it was not observed in adult rats. These findings are consistent with the hypothesis that ppSOM is transiently expressed by motoneurons and that a peptide derived from it may serve a role in the development of the neuromuscular junction.

Aging↗