Biomedical subjects

R Wang

Publications and source records attributed to R Wang.

At least 613 records · Page 34Linked to original sources

PubMed1993

Separation of CD4+ functional responses by peptide dose in Th1 and Th2 subsets expressing the same transgenic antigen receptor.

CD4+ T cells from alpha beta-TCR transgenic mice were used to explore the effect of antigen dose on various functional activities. This transgenic system provides for a source of antigen-specific T cells with the same TCR which can develop into Th1 and Th2 phenotypes under controlled conditions. Of particular interest was to determine if detachment of adherent targets from their substrate could be separated from other functional activities by either antigen dose or functional subset. Using this model, we have found that (a) Th1 and Th2 phenotypes exhibit a similar peptide dose-dependent pattern of detachment and lysis, although Th2 are generally less lytic on both fibroblast and lymphoma targets; (b) detachment and lysis can be dissociated from cytokine production by low peptide doses; (c) detachment and lysis can be physiologically as well as temporally and pharmacologically uncoupled as most targets recovered after detachment by Th2 effectors retain their capacity to proliferate.

Animals↗

PubMed1993

Penile erections induced by vasoactive intestinal peptide and sodium nitroprusside.

The use of vasoactive intestinal peptide (VIP), sodium nitroprusside (SNP), and the reference combination of papaverine, prostaglandin E1, and phentolamine was studied in 22 adult cats. The maximal erectile response (intracavernous pressure, penile length, and rigidity) was produced by intracavernous injection of a combination of 1.65 mg papaverine, 0.5 micrograms PGE1, and 25 micrograms phentolamine. This combination was considered as "control" in order to compare the effect of other agents. VIP and SNP increased the intracavernous pressure and caused erection in a dose-dependent manner with a maximal response obtained with 5 micrograms VIP or 10 micrograms SNP. The duration of peak erection and the total duration of drug effect were significantly shorter with VIP and SNP than with the reference combination (P < 0.01). Epinephrine (30 micrograms) reversed the effects of SNP and significantly shortened the duration of peak action and total effect (P < 0.05). This study supports the use of an in vivo feline model for the evaluation of vasoactive agents and demonstrates that the intracavernous injection of either VIP or SNP can induce penile erection in the adult cat.

Alprostadil↗

PubMed1993

The changes in contractile status of single vascular smooth muscle cells and ventricular cells induced by bPTH-(1-34).

Single smooth muscle cells from rat tail artery and ventricular myocytes from neonatal rat were isolated by repeated enzyme digestion. The change in cell area as determined photographically was used as an index of cell contraction. The photographic areas of single smooth muscle cells bathed in normal Tyrode solution were 403 +/- 22 (n = 13) square micra. Exposure of smooth muscle cells to a modified Tyrode solution containing 60 mM KCl induced cell contraction. This contraction was inhibited by bPTH-(1-34) at a concentration of 1 microM. The inhibitory effect of bPTH-(1-34) was time-dependent with maximum inhibition at 5 min after administration. The photographic areas of ventricular myocytes bathed in the culture medium without fetal calf serum were 516 +/- 47 (n = 29) square micra. At a concentration of 1 microM, bPTH-(1-34) produced a time-dependent contraction in ventricular myocytes as shown by the decrease in the photographic cell area (88 +/- 2% of the control value at 15 min, n = 9, p < 0.01). Furthermore, 1 microM nifedipine inhibited the effect of bPTH-(1-34) on the contraction of ventricular myocytes, indicating that bPTH-(1-34) might exert its action via a calcium channel related mechanism. In addition, bPTH-(1-34) increased the contraction frequency of single ventricular cells, which could also be inhibited by nifedipine. The present study suggests that bPTH-(1-34) directly relaxes precontracted single vascular smooth muscle cells and contracts single ventricular myocytes.

Analysis of Variance↗

PubMed1993

Herpesviruses in chronic encephalitis associated with intractable childhood epilepsy.

Herpesviruses (especially cytomegalovirus [CMV] and Epstein-Barr virus [EBV]) have been implicated in the pathogenesis of chronic (Rasmussen) encephalitis associated with epilepsy. To assess the presence of herpesvirus genes in brain tissue from epileptic children with chronic (usually Rasmussen type) encephalitis, DNA was extracted from surgically resected brain tissue and studied by the polymerase chain reaction using primers specific for CMV, varicella zoster virus, herpes simplex virus, EBV, and human herpesvirus 6 genes. By this technique evidence for the presence of low levels of CMV and EBV genes was detected in most brain specimens from encephalitis patients and in several brain specimens from patients without encephalitis (eg, cortical dysplasia, gliosis, or encephalomalacia) who also had intractable epilepsy. Occasionally, both EBV and CMV genes were found in the same brain. Signal strength for both CMV and EBV was much lower in epileptic brains than in the brains of acquired immunodeficiency syndrome patients with CMV encephalitis or brain lymphoma. We found evidence for infection of the brain by human herpesvirus 6 in only one patient with encephalitis. Polymerase chain reaction technology applied to resected brain tissue from epileptic patients may provide evidence for or against viral-mediated pathogenesis of Rasmussen encephalitis or other types of encephalitis. The small amounts of EBV and CMV genes found suggest that herpesvirus infection of the brain does not directly cause Rasmussen encephalitis.

Autoradiography↗

PubMed1993

Spinal cord edema following freezing injury in the rat: relationship between tissue water content and spinal cord blood flow.

A spinal cord edema model was developed in the rat by inflicting a freezing injury at -40 degrees C for 3 minutes. Regional spinal cord blood flow, tissue water content, and histology were examined. White matter edema had extended several segments by 8 hours after the injury. Tissue water content increased by 20.6% at 24 hours. Spinal cord blood flow in surrounding tissues decreased by more than 25% 4 hours after the injury. The progression of spinal cord edema following freezing injury appeared to be due to disruption of the blood-spinal cord barrier.

Animals↗

PubMed1993

Carotid endarterectomy with an occluded contralateral carotid artery.

Five hundred twenty-six patients who underwent carotid endarterectomy were separated by reviewing those 81 (15%) patients with an occluded contralateral carotid artery and those 445 (85%) with nonocclusion. The population characteristics and surgical indications were similar between the occluded and nonoccluded groups. Ipsilateral plus contralateral perioperative stroke occurred during 11 of 445 operations (2.5%) in which the contralateral carotid was patent, and during which no patient was hemorrhagic. Those patients with contralateral artery occlusion had ipsilateral plus contralateral stroke in 4 of 81 cases of (4.9%) (NS). Intracerebral hemorrhage was responsible for two of four strokes after carotid endarterectomy with contralateral occlusion (p = 0.001). Restenosis to greater than 50% by duplex scanning was more rapid in the occluded group with primary closure (no patch) (p = 0.025) and for men (p = 0.025). Although perioperative safety is comparable, patients with contralateral carotid occlusion may have a greater risk of intracranial hemorrhage and a more rapid rate of restenosis in some subgroups.

Aged↗

PubMed1993

Platelet activating factor and pentoxifylline as human sperm cryoprotectants.

OBJECTIVE: To explore whether the addition of platelet-activating factor (PAF) or pentoxifylline before cryopreservation improves the recovery of motile viable sperm and what role cyclic adenosine monophosphate (cAMP) plays in this recovery. DESIGN: Washed sperm was cryopreserved in the absence of and in the presence of PAF and pentoxifylline. After 2 weeks these samples were quick-thawed and evaluated before and after washing for sperm motility and other motion characteristics. Sperm viability and cAMP concentration were determined to compare the effects of these cryoprotectants. RESULTS: When sperm samples were cryopreserved in the presence of PAF or pentoxifylline, an improvement in the recovery of motile sperm in unwashed and washed post-thaw samples was observed. There were 38% more motile sperm recovered with PAF and 15% more with pentoxifylline when compared with untreated samples. In comparison with the unwashed samples, sperm motility in post-thaw samples was lowered by the washing procedure. When PAF was used as a cryoprotectant, a significant improvement in the linearity and straight line velocity of the post-thaw sperm was observed. When pentoxifylline was used as a cryoprotectant, lateral head displacement was significantly improved in the post-thaw samples than in the control group. Both PAF-and pentoxifylline-treated samples contained a greater number of viable sperm than the control. The cAMP concentrations in post-thaw samples were 12-fold higher in pentoxifylline-treated samples and 4-fold higher in PAF-treated samples when compared with the untreated control. A 4-fold decrease in cAMP concentration was observed in post-thaw control samples compared with fresh-washed sperm. CONCLUSIONS: The results of this study suggest that both PAF and pentoxifylline are useful cryoprotectants for the increased recovery of motile, viable sperm. Although increased recovery of motile sperm in pentoxifylline-treated samples is related to higher cAMP levels, the cryoprotective effect of PAF does not appear to be due to increased cAMP.

Cell Survival↗

PubMed1993

Diterpenoid Alkaloids from Delphinium caeruleum.

A new minor diterpenoid alkaloid, caeruline, was isolated from DELPHINIUM CAERULEUM Jacq. ex Camb. Its structure was elucidated as 1 on the basis of spectral evidence. Along with this new compound, three known diterpenoid alkaloids were also isolated from this plant and identified as tatsiensine, delcosine, and lycoctonine which had not been found in this herb previously.

Journal Article↗

PubMed1993

Trinitrophenyl-ATP blocks colonic Cl- channels in planar phospholipid bilayers. Evidence for two nucleotide binding sites.

Outwardly rectifying 30-50-pS Cl- channels mediate cell volume regulation and transepithelial transport. Several recent reports indicate that rectifying Cl- channels are blocked after addition of ATP to the extracellular bath (Alton, E. W. F. W., S. D. Manning, P. J. Schlatter, D. M. Geddes, and A. J. Williams. 1991. Journal of Physiology. 443:137-159; Paulmichl, M., Y. Li, K. Wickman, M. Ackerman, E. Peralta, and D. Clapham. 1992. Nature. 356:238-241). Therefore, we decided to conduct a more detailed study of the ATP binding site using a higher affinity probe. We tested the ATP derivative, 2',3',O-(2,4,6-trinitrocyclohexadienylidene) adenosine 5'-triphosphate (TNP-ATP), which has a high affinity for certain nucleotide binding sites. Here we report that TNP-ATP blocked colonic Cl- channels when added to either bath and that blockade was consistent with the closed-open-blocked kinetic model. The TNP-ATP concentration required for a 50% decrease in open probability was 0.27 microM from the extracellular (cis) side and 20 microM from the cytoplasmic (trans) side. Comparison of the off rate constants revealed that TNP-ATP remained bound 28 times longer when added to the extracellular side compared with the cytoplasmic side. We performed competition studies to determine if TNP-ATP binds to the same sites as ATP. Addition of ATP to the same bath containing TNP-ATP reduced channel amplitude and increased the time the channel spent in the open and fast-blocked states (i.e., burst duration). This is the result expected if TNP-ATP and ATP compete for block, presumably by binding to common sites. In contrast, addition of ATP to the bath opposite to the side containing TNP-ATP reduced amplitude but did not alter burst duration. This is the result expected if opposite-sided TNP-ATP and ATP bind to different sites. In summary, we have identified an ATP derivative that has a nearly 10-fold higher affinity for reconstituted rectifying colonic Cl- channels than any previously reported blocker (Singh, A. K., G. B. Afink, C. J. Venglarik, R. Wang, and R. J. Bridges. 1991. American Journal of Physiology. 260 [Cell Physiology. 30]:C51-C63). Thus, TNP-ATP should be useful in future studies of ion channel nucleotide binding sites and possibly in preliminary steps of ion channel protein purification. In addition, we have obtained good evidence that there are at least two nucleotide binding sites located on opposite sides of the colonic Cl- channel and that occupancy of either site produces a blocked state.

Adenosine Triphosphate↗

PubMed1993

The vasorelaxant effect of deuterium oxide is secondary to calcium-induced liberation of nitric oxide by endothelial cells.

OBJECTIVE: To test the hypothesis that deuterium oxide (D2O) might induce endothelium-dependent and nitric oxide-mediated vasodilation by altering intracellular calcium concentration ([Ca2+]i) in vascular endothelial cells. DESIGN: The endothelium-dependent and nitric oxide-mediated regulation of vascular tone by D2O was first examined in perfused rat mesenteric arterial beds. Direct effects of D2O on [Ca2+]i in cultured vascular endothelial cells were then examined in order to elucidate a cellular mechanism for D2O-induced vasodilation. METHODS: Vascular reactivity was assayed by measuring the perfusion pressure of isolated rat mesenteric arterial beds. [Ca2+]i in cultured bovine and rat vascular endothelial cells was measured with the fura-2 fluorescence technique. RESULTS: D2O relaxed precontracted rat mesenteric arterial beds with an intact endothelium. This effect of D2O was either inhibited by N omega-nitro-L- arginine (a nitric oxide synthase inhibitor) or eliminated by the removal of endothelium. In cultured bovine aortic, rat aortic, and rat tail artery endothelial cells, D2O induced a biphasic increase in [Ca2+]i, with a characteristic initial transient increase followed by various patterns of sustained [Ca2+]i increase. The sustained phase was entirely dependent on the extracellular calcium entry. CONCLUSIONS: A direct effect of D2O on [Ca2+]i in vascular endothelial cells may be responsible for the endothelium-dependent, presumably nitric oxide-mediated, vasodilation induced by D2O in precontracted vessels. From these results new mechanisms can be explored for the antihypertensive effect of D2O and new avenues can be developed to study the functional integrity of the endothelium-dependent regulation of the vascular tone.

Animals↗

PubMed1993

Neural effects of parathyroid hormone: modulation of the calcium channel current and metabolism of monoamines in identified Helisoma snail neurons.

Neuronal effects of parathyroid hormone (PTH) have been reported in vertebrates. The effect of PTH on invertebrate central neurons within the buccal ganglion of Helisoma trivolvis snails was examined in the present study. By using a vibrating probe, PTH was found to induce a transient calcium-dependent inward current in intact buccal ganglia. Intracellular microelectrode recording revealed that PTH broadened the spontaneous action potential in buccal B5 neurons in situ. By using the whole-cell configuration of the patch-clamp technique, PTH was demonstrated to increase the N-like calcium channel currents in isolated B5 neurons in a concentration-dependent manner. This effect of PTH on the N-like calcium channel currents depended on the activation of a G protein insensitive to pertussis toxin, but was unlikely to be mediated by the cyclic AMP dependent protein kinase. Furthermore, the release of gamma-glutamyl conjugate of dopamine from buccal ganglia was selectively increased in the presence of PTH. These results represent the first demonstration that a vertebrate peptide hormone, PTH, selectively modulates the N-like voltage-dependent calcium channel currents in identified invertebrate neurons. Therefore, a novel role of PTH in the regulation of invertebrate central neural functions is indicated.

Action Potentials↗

PubMed1993

Effects of E. coli sepsis and myocardial depressant factor on interval-force relations in dog ventricle.

We examined whether depressed left ventricular (LV) contractility during Escherichia coli sepsis in dogs was due to a decrease in the fractional release of calcium from the sarcoplasmic reticulum (SR) or a reduction in calcium content in this organelle. To indirectly assess SR calcium availability in a right ventricular (RV) trabecular muscle preparation, we utilized functional indexes of cellular myocardial calcium metabolism, which included rapid-cooling contracture (RCC), an indicator of SR calcium content, and postrest contraction (PRC), an index of calcium availability from the release compartment of the SR. Measurements were made during steady-state stimulation at 0.5 and 1.5 Hz, during which time rest intervals of 30-240 s were periodically imposed. SR calcium availability was measured in RV trabeculae of dogs subjected to 4 h of E. coli sepsis and was compared with calcium availability measured in nonseptic dogs. We further characterized a filterable cardiodepressant substance (FCS), which has been previously shown to be associated with LV depression in this model, to determine whether it produced changes in calcium metabolism similar to those found in sepsis. The results showed that calcium availability from the SR of septic dogs was not impaired. Furthermore, FCS was found in the 10,000- to 30,000-mol wt fraction of plasma and produced changes in PRC in canine trabeculae that were similar to those produced during sepsis. We conclude that, as assessed by PRC and RCC, SR calcium content and release are not impaired in sepsis.

Animals↗

PubMed1993

Alterations in membrane potential after axotomy at different distances from the soma of an identified neuron and the effect of depolarization on neurite outgrowth and calcium channel expression.

1. Intracellular recordings were made from the soma of an identified neuron B5 within the buccal ganglion of the mollusc, Helisoma trivolvis, during axotomy induced by crushing or cutting the esophageal nerve. Axotomy was associated with a rapid depolarization and occasionally a burst of action potentials (injury discharge). The magnitude of the membrane depolarization in the soma in response to axotomy decayed exponentially when the distance between the soma and site of injury was increased. Input resistance measurements taken during axotomy showed that a barrier to current flow formed rapidly and gradually recovered within 2 h. A barrier to the diffusion of intracellularly injected carboxyfluorescein formed at the site of injury within 15 min of axotomy. 2. To examine the effect of chronic depolarization on neurite outgrowth, the extracellular potassium ion concentration [K+]o was manipulated. The membrane potential of neurons B5 exhibited a 51.8 mV/decade potassium dependence between 20 and 150 mM [K+]o. The initiation of neurite outgrowth from axons crushed 800 microns from the soma and bathed in different concentrations of [K+]o was examined by fluorescence microscopy after filling neurons with Lucifer yellow. We compared the percentage of axons with sprouts 9 and 24 h after organ culture in saline containing [K+]o ranging from 0.1 to 50 mM. Sprouting occurred from 33% of neurons B5 in normal saline (1.7 mM [K+]o) after 9 h and from 100% of neurons after 24 h. No sprouting was observed from neurons B5 9 or 24 h after axotomy when bathed in saline containing reduced or elevated concentrations of [K+]o. 3. To examine the effects of chronic depolarizatin on neurite outgrowth over several days, neurons B5 were axotomized close to the soma and maintained in organ culture in Liebovitz medium (defined medium or medium conditioned with central ganglia). Neurite outgrowth was ranked from 0 to 5 after filling neurons with Lucifer yellow, and our analysis indicated that a small increase in neurite outgrowth occurred in medium supplemented with 10 mM potassium. 4. Elevated potassium did not trigger neurite outgrowth from isolated neurons B5 in cell culture within defined medium, but whole-cell patch-clamp analysis revealed that chronic depolarization associated with elevated potassium altered the expression of calcium currents. Low-voltage-activated (LVA) and high-voltage-activated (HVA) calcium currents were detected in acutely isolated neurons B5.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1993

Hepatitis B control in China: knowledge and practices among village doctors.

OBJECTIVES: To guide development of a hepatitis B control program in China, we investigated village doctors' sterilization practices, injection use, vaccination levels, and knowledge and counseling skills. METHODS: The head doctor from each village health station in a rural county (n = 260) completed a self-administered questionnaire. RESULTS: Of the respondents, 94.2% reported adequate sterilization of needles; however, inadequate sterilization of syringes and acupuncture needles was common. Injections were found to be frequent and profitable. Of head doctors, 16.2% reported that most infants in their villages are vaccinated against hepatitis B. There was very high knowledge of modes of hepatitis B transmission, but it was not used to formulate advice for a hypothetical carrier. Knowledge of the consequences, prevalence, and use of condoms to prevent sexual transmission was lower. CONCLUSIONS: The sterilization of acupuncture needles, reuse of syringes, and frequent injections are practices that may transmit the hepatitis B virus. Research into issues of vaccine acceptance is needed to expand immunization. A review of treatment practices and better training in counseling for village doctors is suggested.

Acupuncture Therapy↗

PubMed1993

[Transformation of recombinant plasmid pRK 41 and amplification of full-length coding region of human brain myelin basic protein cDNA].

Transformation of the recombinant plasmid pRK41 containing 2.15 kd human brain myelin basic protein MBP)-coding sequence and 3' untranslated region (1.2 kb) into the E. coli JM109 was made by using Hanahan's method. Positive colonies were screened with digoxigenin oligo labelled rat brain MBP cDNA fragment (1.2 kb). To remove 3' untranslated region and obtain the full-length coding sequence of MBP cDNA, a pair of specific DNA primers was designed and synthesized. A 600 bp fragment was amplified from the recombinant plasmid, extracted from the positive colony by using polymerase chain reaction (PCR). The PCR fragment was isolated, and then digested with BamH I, Kpn I and BamH I + Kpn I. The results of restriction analysis indicate that the PCR amplified fragment is desirable and can be used directly to constract expression vectors.

Base Sequence↗

PubMed1993

[The epidemiological study of subtype risk factors of gastric cancer].

On the basis of understanding multistage pattern of the development of gastric cancer, we designed and carried out a new case-control study. The methods of analysis was multigroup logistic regression analysis. The studied objects were 4 groups of cases and 1 group of control. They were gastric Cancer group, severe dysplasia group, chronic atrophic gastritis accompanied by intestinal metaplasia group, ulcer group and control group, respectively. The control group was confirmed by pathology which showed that the gastric mucosa was normal or had only mild chronic superficial gastritis. The results showed that the risk factors of gastric cancer were living in high incidence area for a long period, low economic income, low animal protein intake, high sweet potato and inkfish intake, eating and drinking too much at one meal and mental injuring. The risk factors of severe dysplasia were low intake of protein, intake of non-fresh fish, large intake of inkfish and salted meat, a family history of gastric cancer.

Adolescent↗

PubMed1993

[PCR amplification of nerve growth factor (beta-NGF) gene in human brain].

Nerve growth factor, an important nutrition factor for neuronal survival, growth, development and maintenance of neuronal functions, consists of three kinds of subunit (alpha 2, beta and gamma 2), but only the subunit beta-NGF has the biological activity. beta-NGF coding sequence is located in a single exon of NGF gene. In our study, a pair of specific primers (29 mers) has been designed and synthesized with ABI 318 A DNA synthesizer. The upstream primer includes an initiation codon and the 1st to 20th base of the exon. The downstream primer includes the complementary sequence of 334 to 354 base of the exon and a stop codon. The full-length DNA fragment of beta-NGF gene has been successfully obtained from human brain cDNA library in lambda ZAPII/EcoRI and human brain genomic DNA respectively by using polymerase chain reaction. The reaction program consists of denaturing at 93 degrees C for 1 min, annealing at 55 degrees C for 1 min, and extending at 72 degrees C for 2 min. Both amplified products of 350 bp in length coincide with the exon coding sequence and are enough for the analysis of restriction mapping, DNA sequencing and construction of expression vector.

Brain↗

PubMed1993

A study on the clinical effect and immunological mechanism in the treatment of Hashimoto's thyroiditis by moxibustion.

71 cases of Hashimoto's thyroiditis were treated by moxibustion and their immune function and thyroid function were observed. It was found that moxibustion was able to reduce the thyroid antibodies in the peripheral blood of the patients with hypothyroidism and to recover their thyroid function. It was also found that moxibustion could lower the thyroid antibody secretory levels and ADCC (antibody-dependent cell-mediated cytotoxicity) activities of the lymphocytes. In addition, the action of moxibustion in reducing the secretion of thyroid antibodies was related to its action of regulating the proportions of T lymphocyte subsets. The results indicate that the treatment of Hashimoto's thyroiditis by moxibustion is probably accomplished through its effect in regulating the relationship among the T lymphocyte subsets.

Adult↗