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Biomedical subjects

X M Wang

Publications and source records attributed to X M Wang.

At least 19 recordsLinked to original sources
PubMed1992

The origins of supraspinal projections to the cervical and lumbar spinal cord at different stages of development in the gray short-tailed Brazilian opossum, Monodelphis domestica.

We have used the retrograde transport of Fast blue (FB) to study the origins of supraspinal projections to the lumbar and cervical spinal cord at different stages of development in the Brazilian, short-tailed opossum, Monodelphis domestica. Monodelphis was chosen for study because its young are born in a very immature state, 14-15 days after copulation, making it possible to manipulate its nervous system in an embryonic state without intra-uterine surgery. When injections of FB were made into the lumbar cord at postnatal day (PD) 1, neurons were labeled within several areas of the reticular formation (the retroambiguus nucleus, the ventral and dorsal reticular nuclei of the medulla, the gigantocellular reticular nucleus, the lateral paragigantocellular reticular nucleus, and the pontine reticular nucleus), the presumptive coeruleus complex, and the lateral vestibular nucleus. In many cases, labeled neurons were also found within the caudal raphe and the presumptive interstitial nucleus of the medial longitudinal fasciculus. The results of immunocytochemical studies provided evidence for catecholaminergic and serotoninergic neurons in the brainstem at PD1 and for axons of both phenotypes in the spinal cord. By PD3, labeled neurons were found within the ventral gigantocellular and ventral pontine nuclei of the reticular formation, the spinal trigeminal nucleus, and the presumptive paraventricular nucleus of the hypothalamus. When injections were made at PD4, neurons were also labeled within the medial and inferior vestibular nuclei, the red nucleus, the mesencephalic nucleus of the trigeminal nerve, the presumptive nucleus of Edinger-Westphal and the lateral hypothalamus. By at least PD7, the pattern of supraspinal labeling was similar to that obtained at older ages and in the adult animal. When FB was injected into the cervical cord at PD1, neurons were labeled in all of the areas labeled by lumbar injections at the same age and in larger numbers. In addition, labeled neurons were found within the ventral gigantocellular and spinal trigeminal nuclei. When cervical injections were made at PD15, labeled neurons were found within the deep cerebellar nuclei and amygdala and by PD17 they were also present within the superior colliculus and cerebral cortex. In some cases, cortical labeling was present outside the areas labeled by comparable injections in adult animals.(ABSTRACT TRUNCATED AT 400 WORDS)

Amidines↗
PubMed1992

Profiling human leukocyte antigens in Vogt-Koyanagi-Harada syndrome.

Human leukocyte antigen typing was performed in 32 consecutive Chinese patients with Vogt-Koyanagi-Harada syndrome and 52 unrelated healthy Chinese individuals. Results indicated that HLA-DR4 was identified in 24 of the 32 patients with Vogt-Koyanagi-Harada syndrome (75.0%), but only in 12 (23.1%) of the 52 control subjects (P = .0003; relative risk, 10.0). Human leukocyte antigen-DQw7, also correlated with the disease, was identified in 19 (59.4%) patients, and in 19 control subjects (36.5%; P = .0230). The two-haplotype association detection demonstrated that HLA-DR4 and HLA-DQw7 were related through linkage disequilibrium, suggesting that the disease was primarily associated with only one of the antigens. The comparison between HLA-DR4-positive and HLA-DR4-negative patients with Vogt-Koyanagi-Harada syndrome in regard to clinical manifestations has shown that the HLA-DR4-positive group had a lower visual acuity at the first visit than did the HLA-DR4-negative group. However, both groups responded well to corticosteroid treatment. No other significant correlations between HLA-DR4 positivity and ocular features, including complications or systemic features, were found. Therefore, we concluded that the presence of HLA-DR4 may represent susceptibility to Vogt-Koyanagi-Harada syndrome, but may not represent specific tissue involvement or determine the prognosis. A decreased frequency of HLA-DQw1 in the patient group was also noticed. Further studies showed a higher percentage of HLA-DQw1 in HLA-DR4-positive control subjects than in the HLA-DR4-positive patients (P = .0308), which indicated that HLA-DQw1 was negatively associated with the disease. This protective effect from HLA-DQw1 was also studied.

Adolescent↗
PubMed1992

Role of the deep mesencephalic nucleus in the antinociception induced by stimulation of the anterior pretectal nucleus in rats.

The present study showed that the inhibitory effect on the tail-flick reflex (TF) of stimulating the deep mesencephalic nucleus (DpMe) was very similar to that produced by stimulation of the anterior pretectal nucleus (APtN). An electrolytic lesion of the ipsilateral DpMe greatly reduced the inhibitory effect of APtN stimulation on the TF. Furthermore, activating the neuronal cell bodies in DpMe but not the fibers of passage by microinjection of L-glutamate into this area was also shown to elicit inhibition of TF. On the other hand, inhibiting the neuronal cells in DpMe by microinjection of gamma-aminobutyric acid produced a marked reduction in the APtN-induced inhibition of TF, which was comparable to that produced by DpMe lesions. It is suggested that the APtN-induced antinociception is, at least in part, mediated via a relay through the DpMe.

Animals↗
PubMed1992

[Induction of Fos-like protein in the rat spinal cord following electroacupuncture stimulation].

The expression of the c-fos proto-oncogene has been regarded as a marker for noxious stimulation. We now report that electroacupuncture (EA) stimulation (100 Hz, 0.3 ms, 1-2-3 mA, 30 min) delivered into the acupoint Sanyinjiao (SP6) could also induce the c-fos expression in the rat spinal cord as demonstrated by immunohistochemical technique using antibody against the c-fos protein product Fos. In rats receiving EA stimulation, numerous cells with Fos-like immunoreactivity (FLI) were observed in both dorsal and ventral horn of the spinal cord with dense labelling in laminae III and IV of the ipsilateral side. Only scattered FLI cells were found in laminae I and II. In contrast, FLI evoked by noxious stimulation (5% formalin injected at the hindfoot subcutaneously) was shown mainly in laminae I and II, rather than in III and IV. The c-fos expression was very low in control animals receiving neither formalin nor EA administration. The present study indicates that the site specificity of the c-fos expression induced by EA is different from that evoked by noxious stimulation. The possibility that EA-induced Fos protein might participate in acupuncture analgesia is currently under investigation.

Animals↗
PubMed1992

Creatine kinase MB isoforms in patients with skeletal muscle injury: ramifications for early detection of acute myocardial infarction.

We measured total creatine kinase (CK), CK-MB isoenzyme, and the MB isoforms in 202 serum and plasma samples from nine groups of patients and normal individuals: 39 with acute myocardial infarction (MI), divided according to time between the onset of chest pain and blood collection (1-6 h, 7-12 h, and 13-48 h); 26 with chest pain for whom an MI was ruled out, sampled at admission; 17 undergoing bypass surgery or cardiac catheterization, sampled within 6 h after either procedure; 17 with acute skeletal muscle injury, sampled within 8 h after injury; 30 marathon runners immediately after a race; 17 runners and other athletes > 12 h after training or a race; 12 with cerebral injury or seizures, sampled at admission; 8 with closed head injury, sampled at admission; and 38 normal subjects. CK-MB (relative index) and MB isoforms (MB2/MB1) were respectively increased in 15% and 75% of MI patients 1-6 h after onset, 94% and 94% after 7-12 h, and 88% and 8% after 12 h, and in 87% and 82% of cardiac surgery patients. MB isoforms were increased in most patients with acute skeletal muscle trauma and in subjects examined after exercise, but were within normal limits in patients for whom MI was ruled out, patients with cerebral trauma, and normal individuals. The relative index of MB/total CK was normal in essentially all individuals in the last groups, including those with acute skeletal muscle trauma. We concluded that the CK-MB isoform ratio is increased in both acute skeletal muscle injury and MI. The isoform ratio is most useful for distinguishing recent from old (> 12 h) injury.

Adolescent↗
PubMed1992

A new human interferon-gamma mutant harboring EGF receptor-interfering sequence possesses high antiproliferative activity.

An interferon gamma (IFN-gamma) mutant gene harboring an additional epidermal growth factor (EGF) sequence at its 3' terminal was constructed and highly expressed in E. coli by using pBV220 as a vector. The new fusion protein-IFN-gamma-EGF possesses not only high antiviral activity, but also high antiproliferative effect as demonstrated by 3H-TdR incorporation method using CN II cells which are rich in EGF receptors.

Amino Acid Sequence↗
PubMed1992

[A clinical study of the effect of wuzi yanzong solution in retarding aging process].

Eighty men ranging from 60 to 80 years old were selected, in whom no disease was found through a thorough check-up except for some senility manifestation diagnosed as deficiency of the kidney. They were randomly divided into two groups, wuzi yanzong solution (WYS) being administered in 50 cases and placebo in 30. After 5 weeks' treatment, symptoms such as hypomnsis, tinnitus, and aching of the back and legs, dribbling after urinary voiding, and nocturia were remarkably improved in the WYS group, but they remained as before in the placebo group. Before the treatment, plasma lipid peroxide (LPO), erythrocyte superoxide dismutase (SOD), blood glutathione peroxidase (GSH-Px), serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH), plasma testosterone (T) and estradiol (E2) levels were determined. In comparison with the results obtained in 33 young men in their twenties, LPO, FSH, LH level and E2/T ratio in the aged were greatly elevated, and SOD, GSH-Px and T markedly lowered. After the treatment, there was remarkable reduction of LPO and E2/T, and increase of SOD and T in the WYS group, but no significant change in the placebo group. The above results not only indicate the beneficial effect of WYS in retarding the aging process, but also suggest the possible mechanism of reducing the peroxidation of fatty acids by enhancing the antioxidant enzymes to inhibit free radical activity.

Aged↗
PubMed1991

Phosphatidylethanolamine synthesis by castor bean endosperm. Intracellular distribution and characteristics of CTP:ethanolaminephosphate cytidylyltransferase.

The intracellular distribution and catalytic properties of CTP: ethanolaminephosphate cytidylyltransferase from endosperm of castor bean (Ricinus communis L. var. Hale) have been studied. This enzyme was confined to membranes, with about 80% of the activity occurring in mitochondria and the rest in endoplasmic reticulum (ER) following sucrose density gradient centrifugation. The mitochondrial location of this enzyme was supported by further purifying mitochondria on Percoll density gradients. The mitochondrial cytidylyltransferase was detected largely in outer membrane fractions, and lost its activity after trypsin treatment, indicating that the active sites are exposed to the cytoplasm. Both mitochondrial and ER cytidylyltransferase required cations for activity; Mg2+ was preferred over Mn2+ and Ca2+. The pH optima both were 6.5. The apparent Km values for ethanolamine phosphate were 143 and 83 microM and those for CTP were 125 and 1010 microM, respectively, for the mitochondrial and ER activities. The mitochondrial cytidylyltransferase reached a maximal velocity of 3.0 nmol/min/mg protein, whereas ER cytidylyltransferase was 0.424 nmol/min/mg protein. These findings reveal that the majority of the cytidylyltransferase activity in castor bean endosperm is not closely associated with ethanolaminephosphotransferase (predominantly in ER) which catalyzes the subsequent reaction in the synthesis of phosphatidyl-ethanolamine by a nucleotide pathway. The possible roles of these enzymes in phosphatidylethanolamine synthesis in plants are discussed.

Catalysis↗
PubMed1991

Ethanol reduces vasopressin release by inhibiting calcium currents in nerve terminals.

Ingestion of ethanol (EtOH) is known to result in a reduction of plasma arginine-vasopressin (AVP) levels in mammals. We examined the basis for this effect using a combination of biochemical and electrophysiological techniques. Release of AVP from nerve terminals isolated from the rat neurohypophysis was very sensitive to EtOH, with significant reductions in AVP release evident in 10 mM EtOH. However, EtOH did not affect the release of AVP from terminals which had been permeabilized with digitonin, suggesting that voltage-gated calcium channels might be the target of EtOH's actions. Patch clamping of these terminals indicated that both inactivating and long-lasting calcium currents were reduced in EtOH, but the long-lasting currents were more sensitive (significant reductions in 10 mM EtOH). EtOH-induced decreases in plasma AVP levels can be explained by EtOH's inhibition of calcium currents in the nerve terminals.

Animals↗
PubMed1991

Direct identification of individual vasopressin-containing nerve terminals of the rat neurohypophysis after 'whole-cell' patch-clamp recordings.

The membrane currents in rat neurophypophysial nerve terminals, which contain either vasopressin or oxytocin, have been previously recorded using the 'whole-cell' patch-clamp technique. Interpretation of the electrophysiological data would be significantly strengthened by the ability to correlate them with knowledge of the peptide contents of the terminals being studied. Here, a novel method for detection of the peptide hormone, arginine vasopressin, in those individual isolated terminals is described. The unique aspect of this procedure is that the contents of the terminal are aspirated into the recording electrode after 'whole-cell' patch-clamp recording, and then a highly sensitive dot immunobinding assay allows identification of the peptide contents in the terminals.

Animals↗
PubMed1991

A fast, transient K+ current in neurohypophysial nerve terminals of the rat.

1. Nerve terminals of the rat posterior pituitary were acutely dissociated and identified using a combination of morphological and immunohistochemical techniques. Macroscopic terminal membrane currents and voltages were studied using the whole-cell patch clamp technique. 2. In physiological solutions, depolarizing voltage clamp steps, from a holding potential (-80 mV) similar to the normal terminal resting potential, elicited a fast, inward followed by a fast, transient, outward current. 3. The threshold of activation for the outward current was -60 mV. The outward current quickly reached a peak and then decayed more slowly. The decay was fitted by two exponentials with time constants of 21 +/- 2.9 and 143 +/- 36 ms. These decay constants did not show a dependence on voltage. The time to peak of the outward current decreased and the amplitude increased with increasingly depolarized potential steps. 4. The outward current was blocked by the substitution of K+ with Cs+ and its reversal potential was consistent with a potassium current. 5. The transient outward current showed steady-state inactivation at more depolarized (than -80 mV) holding potentials with 50% inactivation occurring at -47.9 mV. The time course of recovery from inactivation was complex with full recovery taking greater than 16 s. 6. 4-Aminopyridine (4-AP) blocked the transient outward current in a dose-dependent manner (approximately IC50 = 3 mM), while charybdotoxin (4 micrograms/ml) and tetraethylammonium (100 mM) had no effect on the current amplitude. 7. Lowering external [Ca2+] had no effect on the fast, transient outward current nor did the calcium channel blocker Cd2+ (2 mM). 8. The neurohypophysial outward current reported here corresponds most closely to IA, and not to the delayed rectifier or Ca2(+)-activated K+ currents. Neurohypophysial IA, however, appears to be different from the outward currents found in the cell bodies in the hypothalamus which project their axons to the posterior pituitary. 9. Under current clamp, evoked action potential duration increased (122%) upon application of 5 mM-4-AP, indicating that IA is involved in neurohypophysial spike repolarization. 10. The existence of this current could help explain why maximal peptide release only occurs in response to bursts of electrical activity invading the nerve terminals.

4-Aminopyridine↗
PubMed1991

O6-methylguanine-DNA methyltransferase and human cancer chemotherapy.

Two kinds of human tumor cell strains having different activity of O6-methylguanine-DNA methyltransferase (O6-MT) were transplanted into nude mice. Then the mice were injected intraperitoneally with bifunctional alkylating agent 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU). The tumors with low O6-MT activity were quickly suppressed or cured. The result suggests that some tumors, if provisionally determined with low O6-MT activity, might be efficiently cured by treatment with ACNU. This probably opens a new way for human cancer chemotherapy.

Animals↗
PubMed1991

Calcium currents and peptide release from neurohypophysial terminals are inhibited by ethanol.

The effects of EtOH on peptide release and on high-threshold, voltage-activated calcium (Ca++) channels were examined in acutely dissociated rat neurohypophysial terminals. These terminals release the peptide hormones, arginine vasopressin (AVP) and oxytocin. Release of AVP from isolated intact neurohypophyses, induced by either electrical stimulation or elevated potassium, was inhibited by clinically relevant concentrations of EtOH. "Whole-cell" patch-clamp recording methods were used to study the effects of EtOH on voltage-activated Ca++ currents (ICa) in the peptidergic nerve terminals. Amplitudes of both fast-inactivating ICa and long-lasting ICa were reduced in EtOH, and the reduction in ICa did not result from a shift in its current-voltage or steady-state inactivation relationships. Only the fast-inactivating component recovered after removal of EtOH. The effects of EtOH on ICa could not be attributed to changes in osmolarity. In contrast to ICa, the fast, transient K+ current was insensitive to EtOH. These results suggest that EtOH-induced reduction of ICa in the peptidergic nerve terminals produces a decrease in AVP release, resulting in lowered plasma AVP levels.

Animals↗
PubMed1990

Expression of the acetylcholine receptor delta-subunit gene in differentiating chick muscle cells is activated by an element that contains two 16 bp copies of a segment of the alpha-subunit enhancer.

The acetylcholine receptor is a multimeric membrane protein whose expression is activated during muscle differentiation and upon denervation of adult muscle. To gain insight into the coordinate expression of receptor subunits during myogenesis we have analyzed the chick muscle receptor delta-subunit gene upstream region. The delta-subunit gene lacks canonical promoter elements (CCAAT and TATA boxes). Nuclease protection and primer extension analysis revealed that transcription starts at six major and several minor sites between -110 and -30 upstream of the translational initiation site; two sites, at positions -77 and -66, give rise to approximately 50% of all transcripts. Using nested deletions of the proximal 960 bp of the 5' flanking region of this gene we have identified a 62 bp sequence (-207 to -146) that activates transcription in a position independent manner. This enhancer-like element is activated during myotube formation; it contains two distinct functional moieties, each resembling the same 16 bp portion of the stage and tissue specific alpha-subunit gene enhancer which we have characterized previously [Wang et al. (1988) Neuron, 1, 527-534]. This common element, which also comprises several previously proposed skeletal muscle specific motifs [Buskin, J. N. and Hauschka, S. D. (1989) Mol. Cell Biol., 9, 2627-2640; Mar, J. H. and Ordahl, C. P. (1988) Proc. Natl. Acad. Sci. USA, 85, 6404-6408], may account for the coordinate expression of the two subunits. The cell specificity of the delta-subunit gene 5' flanking region is partly due to the enhancer, partly to an inhibitory element upstream of -207.

Animals↗