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Biomedical subjects

M Wang

Publications and source records attributed to M Wang.

At least 1,027 records · Page 57Linked to original sources
PubMed1986

The cytomatrix regulates "resolute" transport in erythrophores.

Light microscopic studies have indicated that most microtubule-directed transport is either saltatory or resolute in nature. The latter form of transport is an intriguing phenomenon, because it commonly involves the unidirectional bulk motion of an organelle(s) such as chromosomes in dividing cells or pigment granules in chromatophores. We have investigated the ultrastructural and biochemical basis for the resolute transport of pigment in chromatophores. Light and EM studies of erythrophores in situ have clearly shown that when the microtubules were completely removed with nocodazole, resolute transport continued and was stimulated by aggregating and dispersing agents. Light and electron microscopic studies of cultured erythrophores permeabilized with digitonin indicated that resolute motion was produced by a cytomatrix of 3 to 7 nm filaments. Immunofluorescent analysis with several monoclonal antibodies raised against MAP-2 further demonstrated that MAP-2 was an important component of the contractile cytomatrix that powers pigment aggregation and dispersion. We conclude that a microtubule-associated cytomatrix normally produces resolute pigment transport in chromatophores.

Animals↗
PubMed1986

[Carcinoma of esophagus treated by 8MV X-ray and checked by simulator].

From January 1, 1978 to December 31, 1983, 570 patients with carcinoma of esophagus were treated by 8 MV X-ray and checked by the Philips simulator. In order to assess their value, a series of 3,798 patients reported previously was used for comparison. To further evaluate the effect of 8 MV X-ray and simulator separately, a series of 154 patients was treatment by non-8 MV X-ray during the same period. The results showed that the 1 and 3 year survival rates of 8 MV X-ray series were better than the 3,798 series (P less than 0.01). It means that after the use of simulator and 8 MV X-ray the survival rates were improved. As compared to the radiation other than 8 MV X-ray, there was no difference between 8 MV X-ray and non-8 MV X-ray series, which means that the improvement may have been due to the better localization by the simulator. Having more importance, no radiation myelitis was found after the use of simulator. The sex, age, length, location, X-ray type, NSD and causes of failure were compared in these groups.

Adult↗
PubMed1986

[Superior sulcus cancer of the lung--report on 45 patients].

From 1960 to 1980, 45 patients with superior sulcus cancer of the lung were seen in our hospital. 39 were male and 6 were female. The youngest was 28 years old and the eldest was 75. The presenting symptoms and signs were back and shoulder pain in 32 patients, compression of the brachial plexus in 17, Horner's syndrome in 12, supraclavicular mass in 11, superior cava vena obstruction in 4, shadow in the apex in 45, destruction of the rib in 19 (10 in the second rib), destruction of the adjacent vertebra in 8 (5 in T3) and destruction of the clavicle in 1. In 18 patients proved by pathology and cytology, 8 were adenocarcinoma, 3 squamous cell carcinoma, 3 undifferentiated and 4 unclassified carcinoma. 27 patients were diagnosed by X-ray films. 40 patients were admitted for treatment. 3 recieved chemotherapy alone and all of them died in one year. Of the 6 treated by radiation plus chemotherapy, 3 survived for one year but all died in two years. 2 were treated by radiation plus operation and none survived for more than 3 years. 29 were treated by radiation only. The 1, 3 and 5 year survival rates were 51%, 13.7% and 6.9%. Destruction of the rib or the adjacent vertebral body was irrelative to the prognosis but the presence of supraclavicular mass reduced the survival rate. Cause of death was local recurrence in 48% (13/27) and distant metastasis in 48% (13/27). The authors suggest that radical en bloc resection together with radiation the worth further study.

Adenocarcinoma↗
PubMed1986

Effects of butylated hydroxyanisole on the tumorigenicity and metabolism of N-nitrosodimethylamine and N-nitrosopyrrolidine in A/J mice.

Female A/J mice were maintained on NIH-07 diet or on NIH-07 diet containing butylated hydroxyanisole (BHA, a mixture of 2- and 3-tert-butyl-4-hydroxyanisole), 5 mg/g, for 1 week prior to and during 10 weeks of treatment with N-nitrosodimethylamine (NDMA) or N-nitrosopyrrolidine (NPYR), administered in the drinking water. Twenty weeks after nitrosamine treatment ended, mice were sacrificed and lung adenomas were counted. BHA inhibited NDMA tumorigenesis but enhanced NPYR tumorigenesis. Treatment of A/J mice for three weeks with BHA (5 mg/g) added to semisynthetic diet increased whole lung microsomal alpha-hydroxylation of NDMA and NPYR, as measured by aldehyde production, and increased lung and hepatic glutathione-S-transferase activities. No evidence was found for formation of S-methylglutathione in incubations with NDMA and hepatic supernatants obtained from BHA treated or control mice. Four h after gavage of NDMA, levels of 7-methylguanine in the lung DNA of mice treated with BHA were higher than in the lung DNA of control mice, but levels of O6-methylguanine in the two groups were the same. The results of this study indicate that BHA treatment increases the microsomal metabolic alpha hydroxylation of both NDMA and NPYR, but has differential effects on their tumorigenic activities.

Animals↗
PubMed1986

Intramucosal gastric carcinoma in a patient with familial polyposis coli.

Upper gastrointestinal polyps commonly occur in patients with familial polyposis coli; but the occurrence of gastric carcinoma is very rare in this disorder. We report a case of intramucosal gastric carcinoma in a patient with familial polyposis coli and multiple gastrointestinal adenomatous polyps.

Adenocarcinoma↗
PubMed1985

EEG effects of subcutaneous and intracerebroventricular injections of arginine vasopressin in the rat.

Several studies have suggested that arginine vasopressin (AVP) may act centrally as a neurohormone or neuromodulator to produce electrophysiological and behavioral effects. However, there are few reports of EEG effects of AVP in unanesthetized, behaving animals. In the present study the EEG effects of "behaviorally relevant" subcutaneous (SC) doses of AVP (6 micrograms/kg) known to raise blood pressure were compared to "behaviorally relevant" intracerebroventricular (ICV) doses (0.1-1.0 ng) and multiple "toxic" ICV doses (1.0 microgram) of AVP. Central injections of toxic doses of AVP produced behavioral arrest, bodily barrel rolling, and EEG slowing, but did not induce electrographic signs of seizure activity. Comparison of the spectral characteristics of the EEG revealed some similarities in the distribution of power between SC and the 1.0 ng ICV dose; whereas ICV doses of 0.1 and 0.5 ng produced power distributions that were different from those seen following saline or SC doses of AVP. The similarities in EEG activity between SC injections and the 1.0 ng ICV dose suggest a common brain state may be induced by the two routes of administration in those dose ranges.

Animals↗
PubMed1985

cAMP induces a transient elevation of cGMP levels during early culmination of Dictyostelium minutum.

Oscillatory cAMP signals very likely organize the cell movement which leads to fruiting body construction in Dictyostelium minutum [Schaap, P., Konijn, T.M. and Van Haastert, P.J.M.: Proc. Natl. Acad. Sci. USA 81, 2122-2126 (1984)]. Stimulation with cAMP induces a transient elevation of cGMP in cells at the early culmination stage, which peaks at 12-18 s. A half maximal cGMP response is induced by 10(-7) M cAMP and saturation of the response is reached at 10(-5) M cAMP. No cGMP accumulation was induced by stimulation of vegetative or aggregative cells of D. minutum by cAMP. Since the transient increase of cGMP is most likely involved in the transduction of chemotactic signals, our results indicate that cAMP signals organize fruiting body formation by inducing chemotaxis inside the aggregate.

Chemotaxis↗
PubMed1985

Endoscopic sclerotherapy for bleeding rectal varices: a case report.

Rectal varices are not hemorrhoids and they are dilated submucosal veins connecting the middle and inferior hemorrhoidal veins. These rectal varices may occur in patients with portal hypertension because of the formation of portosystemic shunts. Like esophageal varices, the rectal varices may also bleed massively. Herein we report a case of such bleeding which was successfully controlled with endoscopic sclerotherapy to the rectal varices.

Endoscopy↗
PubMed1985

Merkel cell tumor with liver metastases: presentation as fulminant hepatic failure.

This report demonstrates that hepatic metastases can present with fulminant hepatic failure and that liver enzyme abnormalities may not become prominent until there has been massive replacement of the liver. The CT scan of liver may not demonstrate diffuse liver metastases as seen in this patient. Merkel cell tumor or trabecular neuroendocrine skin tumor is a previously unreported cause for the development of the syndrome of hepatic failure due to liver metastases.

Adenocarcinoma↗
PubMed1985

De novo carcinoma of the rectum: a case report.

There is strong evidence in the literature to suggest that most of the colorectal carcinomas arise from adenomatous polyps. Yet, rare carcinomas may arise de novo and we are reporting such a case of intramucosal rectal carcinoma occurring in a 47-year-old healthy man.

Adenocarcinoma↗
PubMed1984

Synaptic connections from large muscle afferents to the motoneurons of various leg muscles in man.

Cross-correlations between stimuli delivered to peripheral nerves and the discharges of single, voluntarily activated, motor units can provide information about facilitatory and inhibitory projections to single spinal motoneurons in man. The projection frequency, under the given circumstances, of a facilitatory or inhibitory pathway can be obtained from the proportion of the sampled motor units of a given muscle showing the facilitatory or inhibitory effect. Deductions about the shape and relative amplitude of the underlying post-synaptic potentials can be made from the profile of the changes in firing probability. This technique has been used to explore the projections of low threshold muscle afferents to motoneurons of various leg muscles in man. Homonymous facilitation was demonstrated to all the sampled motor units of soleus (SOL), medial gastrocnemius (MG), tibialis anterior (TA) and vastus medialis (VM) and is presumed to represent the effects of the composite muscle spindle group Ia EPSP. Heteronymous facilitation was demonstrated between certain synergists. The projection frequency was less and the magnitude of the change in firing probability was smaller than for homonymous facilitation. SOL motoneurons, however, were not facilitated from low threshold afferents in the medial gastrocnemius nerve. Reciprocal inhibition was demonstrated between certain antagonists. The majority of the sampled motor units of SOL, however, were facilitated from low threshold afferents in the common peroneal nerve. The threshold for this facilitation was higher than for the homonymous facilitation elicited from this nerve and thus a different class of afferents and/or intercalated interneurons may be involved. There are projections across the knee joint in man. Motor units in vastus medialis (VM) were facilitated from low threshold afferents in the common peroneal nerve. It is likely that these reflex connections, which differ from those in other species, reflect the functional relationships between various lower limb muscles in man.

Adult↗
PubMed1984

GTP cyclohydrolase I deficiency, a new enzyme defect causing hyperphenylalaninemia with neopterin, biopterin, dopamine, and serotonin deficiencies and muscular hypotonia.

A 4-year-old patient is described with hyperphenylalaninemia, severe retardation in development, severe muscular hypotonia of the trunk and hypertonia of the extremities, convulsions, and frequent episodes of hyperthermia without infections. Urinary excretion of neopterin, biopterin, pterin, isoxanthopterin, dopamine, and serotonin was very low, although the relative proportions of pterins were normal. In lumbar cerebrospinal fluid, homovanillic acid, 5-hydroxyindoleacetic acid, neopterin and biopterin were low. Oral administration of L-erythro tetrahydrobiopterin normalized the elevated serum phenylalanine within 4 h, serum tyrosine was increased briefly and serum alanine and glutamic acid for a longer time. Urinary dopamine and serotonin excretion were also increased. Administration of an equivalent dose of D-erythro tetrahydroneopterin was ineffective and demonstrated that this compound is not a cofactor in vivo and cannot be transformed into an active cofactor. GTP cyclohydrolase I activity was not detectable in liver biopsies from the patient. The presence of an endogenous inhibitor in the patient's liver was excluded. This is the first case of a new variant of hyperphenylalaninemia in which the formation of dihydroneopterin triphosphate and its pterin metabolites in liver is markedly diminished. Normal activities of xanthine oxidase and sulfite oxidase were apparent since uric acid levels were normal and no increase in hypoxanthine, xanthine, and S-sulfocysteine concentrations could be observed in urine. It is concluded that the molybdenum cofactor of these enzymes may not be derived from dihydroneopterin triphosphate in man. Also, since no gross abnormalities in the patient's immune system could be found, it seems unlikely that dihydroneopterin triphosphate metabolites, such as neopterin, participate actively in immunological processes, as postulated by others. See Note added in proof.

Adolescent↗
PubMed1984

The possible involvement of oscillatory cAMP signaling in multicellular morphogenesis of the cellular slime molds.

The involvement of pulsatile chemoattractant emission and signal relay in aggregation and multicellular morphogenesis of a variety of cellular slime mold species was investigated. The species differ from each other in the developmental stage when pulsatile signaling first becomes evident. In D. discoideum, D. mucoroides, and D. purpureum pulsatile signal emission starts in the preaggregative field. In D. vinaceo-fuscum, D. mexicanum, P. violaceum, and P. pallidum the aggregation centers shifts from continuous to pulsatile secretion of chemoattractant during the aggregation process. In D. minutum pulsatile signaling starts after the completion of aggregation and slightly before the onset of culmination. Tip formation is a consequence of continued attraction of amoebae inside the aggregate to the center of signal emission. The occurrence of pulsatile signaling at an early stage of development is correlated with the capacity of the tip (signaling center) to organize a relatively large number of cells into a single fruiting body. Several lines of evidence suggest that cAMP is probably involved in the coordination of morphogenetic movement in the multicellular stage of all investigated species.

Cell Membrane↗
PubMed1984

Microtubule polarity and the direction of pigment transport reverse simultaneously in surgically severed melanophore arms.

The transport of pigment through the long cytoplasmic extensions (arms) of teleost melanophores is a microtubule-dependent event. We have severed the arms from melanophores to test whether microtubules isolated from the centrosome maintain their original polarity and disposition. In addition, we have tested whether arms containing microtubules of mixed polarities alter the direction of pigment transport. We find that microtubules within severed arms eventually change their polarity and reorganize from the arm center as if to form a new minicell. Concomitant with this change is a reversal in the direction of pigment transport.

Animals↗