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Biomedical subjects

M Tang

Publications and source records attributed to M Tang.

At least 145 records · Page 8Linked to original sources
PubMed1992

Prior exposure to a running wheel and scheduled food attenuates polydipsia acquisition.

Groups of rats were given different histories before exposure to daily, 2-h fixed-interval (FI) 1-min food-schedule sessions with water available. In a previous study, a group with a history of chronic exposure to FI 1-min sessions without water subsequently had a reduced rate of acquisition and final level of schedule-induced polydipsia compared to a control group lacking this history. In the present study, groups with histories of chronic exposure to FI 1-min sessions and a concurrent running wheel were even more attenuated in their subsequent acquisition of polydipsia. Substitution of 5% ethanol for session water in the final phase produced a convergence in group intakes, except for a group which continued to have access to the running wheel. The ethanol intake of this group was relatively suppressed.

Animals↗
PubMed1991

CD4 cells in HIV-1 infected hemophiliacs: effect of factor VIII concentrates.

The goal of this study was to determine the long-term clinical outcome of Human Immunodeficiency Virus (HIV) infection in a group of HIV-seropositive hemophiliacs for whom the dates of seroconversion were known and to investigate whether the use of monoclonal antibody purified factor (high purity) concentrate and treatment with zidovudine may alter the effect of HIV infection in seropositive hemophiliacs. Twenty-eight hemophiliacs were followed for up to 9 years after seroconversion. In addition, 13 seropositive patients who elected to receive (high purity) factor VIII concentrate for up to 1.5 years were compared to a contemporaneous concurrent control group of 8 seropositive patients treated with intermediate purity factor VIII concentrate, and then both groups were followed for an additional 1.5 years while receiving zidovudine. The acquired immunodeficiency syndrome (AIDS) developed in 9 of 28 patients (33%) from 1 to 9 years following seroconversion. CD4 cell count declined at a rate of 13.5% per year for the cohort but for persons 25 years and above the rate was significantly higher (17.5 +/- 9.2% per year vs. 9.5 +/- 4.7%, mean +/- SD, p less than 0.05) than in those under 25. All three patients who had undergone splenectomy developed AIDS. Subjects treated with high purity concentrates, with the exception of one patient who developed the nephrotic syndrome secondary to amyloidosis, had stable CD4 cell counts. On the other hand, all patients receiving intermediate purity concentrates had a decline in CD4 cells, and the difference from initial levels was highly significant (p = 0.01). The CD4 cell concentrations in these patients were stable after treatment with zidovudine.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

Midazolam withdrawal and discriminative motor control: effects of FG 7142 and Ro 15-1788.

Rats chronically drank either water or midazolam solution (0.1 mg/ml) in daily, 3-h schedule-induced polydipsia sessions and were evaluated in daily motor control sessions after polydipsia when midazolam metabolite levels had fallen to zero (withdrawal). Under midazolam polydipsia, animals orally self-administered between 21 and 38 mg/kg daily. The effect of acute drug administration [midazolam (0.75-3 mg/kg, SC), FG 7142 (1-8 mg/kg, IP), Ro 15-1788 (10-20 mg/kg, IP)] on motor control performance was similar after either chronic water or midazolam polydipsia. Thus chronic, oral midazolam self-administration did not lead to tolerance to the motor impairment produced by SC midazolam, nor did the daily discontinuation lead to impaired motor performance, nor had these performances, which occurred after daily elevated midazolam metabolite levels had reached zero (withdrawal), become sensitized to the effects of either the benzodiazepine inverse agonist FG 7142 or the agonist Ro 15-1788.

Animals↗
PubMed1991

Behavioral tolerance to flurazepam.

Rats were trained to earn 180 food pellets in daily, fixed-interval 1-min sessions. When performance had stabilized, a Before group was given a weekly 16 mg/kg flurazepam injection IP for 3 weeks immediately before the sessions, while an After group received their weekly injections immediately after the sessions. Then, the After group received 3 such weekly injections before the sessions. Behavioral tolerance developed by the 2nd flurazepam injection for the Before group, but for the After group, the 3 postsession flurazepam injections resulted in subsequent tolerance to presession flurazepam injection for session lever presses, but not for the time taken to earn 180 pellets. Dispositional tolerance to the serum elimination rate of flurazepam did not develop over the course of 3 injections. Behavioral suppression still evident in the initial portion of sessions with the 2nd and 3rd presession injection coincided with the duration of rising and high levels of serum flurazepam.

Animals↗
PubMed1991

Mosaic partial trisomy 17q2.

Examination of an infant born after prenatal diagnosis of mosaic partial trisomy 17q2 showed the unique phenotypic features of this chromosomal abnormality, that is, frontal bossing, large mouth, brachyrhizomelia, and hexadactyly. Amniocentesis was performed because of polyhydramnios and ultrasound diagnosis of fetal craniofacial dysmorphology and rhizomelic shortening of the limbs. Chromosomal mosaicism was restricted to fetal tissue and amniotic fluid cells. The placental chromosomal complement was normal, suggesting that the abnormality developed after differentiation of embryonic and trophoblastic cells. This emphasises the usefulness of cytogenetic evaluation of placental, fetal, and amniotic fluid cells in delineating the pathogenesis of congenital abnormalities.

Abnormalities, Multiple↗
PubMed1991

Are demented patients with Parkinson's disease accurately reflected in prevalence surveys? A survival analysis.

We re-reviewed 257 patient records previously reviewed for an incidence study of dementia in Parkinson's disease (PD) to determine the frequency, date of death, and cause of death. We posited that if disease duration is shortened when dementia occurs, then dementia may be far more common than reflected in prevalence studies. There were 17 deaths among 65 demented patients and 28 deaths among 168 nondemented patients. When we matched a subset of the nondemented patients to the demented patients by age and disease duration distributions, the demented subjects had significantly more deaths (p less than 0.02), and survival among demented subjects was decreased (p less than 0.05). Dementia was a significant predictor of death in this sample. We conclude that dementia reduces survival in patients with PD. Incidence is a much better measure of dementia in PD than prevalence because shortened duration makes it less likely to detect dementia in prevalence surveys.

Aged↗
PubMed1991

[Studies on chemical constituents of Fritillaria in Hubei. XIII. Isolation and structure elucidation of hupehemonoside].

A new D/E cis-5-cevanine alkaloidal glucoside, C33H53NO8, mp 206-208 degrees C, named hupehemonoside, was isolated together with three known alkaloids, peimine, peiminine and ebeiensine from the fresh bulb of Fritillaria hupehensis Hsiao et K. C. Hsia. On the basis of the IR, 1H-NMR, 13C-MNR, FAB-MS and EI-MS of hupehemonoside, it has been established as 5 alpha, 14 alpha, 17 beta, 22 beta-cevanine-20 beta-hydroxyl-3 beta-O-beta-D-glucoside (IV).

Antitussive Agents↗
PubMed1990

Distinct functional roles of the two intracellular phosphatase like domains of the receptor-linked protein tyrosine phosphatases LCA and LAR.

Protein tyrosine phosphorylation is regulated by both protein tyrosine kinases and protein tyrosine phosphatases (PTPases). Recently, the structures of a family of PTPases have been described. In order to study the structure-function relationships of receptor-linked PTPases, we analyzed the effects of deletion and point mutations within the cytoplasmic region of the receptor-linked PTPases, LCA and LAR. We show that the first of the two domains has enzyme activity by itself, and that one cysteine residue in the first domain of both LCA and LAR is absolutely required for activity. The second PTPase like domains do not have detectable catalytic activity using a variety of substrates, but sequences within the second domains influence substrate specificity. The functional significance of a stretch of 10 highly conserved amino acid residues surrounding the critical cysteine residue located in the first domain of LAR was assessed. At most positions, any substitution severely reduced enzyme activity, while missense mutations at the other positions tested could be tolerated to varying degrees depending on the amino acid substitution. It is suggested that this stretch of amino acids may be part of the catalytic center of PTPases.

Amino Acid Sequence↗
PubMed1990

Simultaneous pulsed Doppler velocimetry of fetal aorta and inferior vena cava. Diagnosis of fetal congenital heart block; two case reports.

A simple technique for the diagnosis of fetal congenital heart block by simultaneous Doppler blood-flow velocimetry of the fetal abdominal aorta and inferior vena cava is described. Furthermore, a simple method of monitoring the fetal atrial reactivity during the antenatal period; and simultaneous recording of atrial and ventricular rates during labour are also described. These simple techniques can be applied for the diagnosis and monitoring of the fetus in other types of cardiac arrhythmias.

Adult↗
PubMed1990

Motor performance decrement by midazolam: antagonism by Ro 15-1788 and CGS 8216.

Rats were trained in a fine motor control performance that required operation by a paw of a force transducer so that it remained between upper and lower limits of a force band for a continuous 1.5-sec period to deliver each food pellet. Acute doses of midazolam (0.75-3.0 mg/kg, SC) impaired indices of motor performance in a graded, dose-related fashion. When administered alone, Ro 15-1788 (0.1-5.0 mg/kg, SC) had no effect on motor behavior while CGS 8216 (0.5 and 1.0 mg/kg, IP) alone had small effects. In general, the motor performance decrements produced by midazolam were antagonized in a dose-related fashion by both Ro 15-1788 and CGS 8216.

Animals↗
PubMed1990

Diazepam and discriminative motor control: acute, chronic and withdrawal effects.

Rats were trained to hold a force transducer operated with a paw so that it remained between upper and lower limits of a force band for a continuous 1.5-sec period to deliver each food pellet. Acute doses of diazepam impaired measures of this performance. Separate groups received chronic diazepam injections (6 mg/kg, IP) either presession (Before Group) or postsession (After Group), or presession vehicle (Vehicle Group). The After and Vehicle Groups demonstrated that neither chronic postsession diazepam, nor time alone, altered motor performance. The performance of the Before Group was affected by the daily diazepam, and although tolerance to the impairment developed, it was incomplete. Late in the chronic-administration phase (after 75 days) a toxic effect of the suspending agent became evident in all groups as a decrease in work rate, although the other performance indices were not affected. The withdrawal of diazepam from the Before Group led to improved performance which returned to the original baseline level.

Animals↗
PubMed1990

Schedule-induced cocaine drinking: choice between cocaine and vehicle.

Rats were exposed to daily 3-hr schedule-induced polydipsia sessions (fixed-time 1-min food-pellet delivery) with two drinking fluids available: cocaine solution and water. Fluid position was alternated daily. Polydipsia occurred mostly from a preferred-side spout (position preference) until cocaine solution concentration was increased to between 0.52 and 1.04 mg/ml and animals drank mostly water. Within a lower concentration range (0.28-0.6 mg/ml) maximum session cocaine intakes ranged from 54.3 to 120.1 mg/kg. Postsession serum cocaine levels were about 200 ng/ml. At individually chosen cocaine solution concentrations, the addition of saccharin to the solution did not increase cocaine intake, but a compound solution (saccharin plus glucose) did. With progressive dilution of the compound vehicle, an almost complete preference for cocaine solution was maintained. But with a return to water as the vehicle, animals reverted to a position preference after a few sessions, although one maintained a clear cocaine preference. Schedule-induced polydipsia produced chronic, oral self-administration of cocaine resulting in pharmacologically significant intakes and serum levels.

Animals↗
PubMed1990

Schedule-induced oral self-administration of cocaine and ethanol solutions: lack of effect of chronic desipramine.

Groups of rats drinking either solutions of cocaine HCl (0.16 mg/ml), ethanol (2.5% v/v), or water, drank excessive, equivalent volumes in daily, 3-h sessions of food-pellet delivery under a fixed-time 1-min (FT 1-min) schedule. During single-session exposures to pellet-delivery schedules using longer inter-pellet values (FT 3- or 5-min probe sessions), the cocaine and ethanol groups, but not the water group, drank greater ml/pellet amounts, confirming previous research. Inasmuch as enhanced ml/pellet intake during the greater FT probes correlated with the abuse potential of the drinking solution in previous research, the effect of chronic desipramine HCl (2 mg/kg, i.p. daily) on this enhanced intake response was determined. For all groups, chronic desipramine treatment (2 mg/kg was judged to be the maximum dose free of non-specific, suppressive effects) affected neither FT 1-min schedule-induced polydipsia nor did it affect the enhanced ingestional response to the greater FT probes for the cocaine and ethanol groups. Chronic administration of desipramine may have therapeutic efficacy in treating cocaine abuse only in subjects attempting to refrain from cocaine who are aided in their passage through a withdrawal phase by desipramine.

Alcohol Drinking↗
PubMed1990

Prenatal diagnosis of congenital fetal arrhythmias by simultaneous pulsed Doppler velocimetry of the fetal abdominal aorta and inferior vena cava.

Various methods have been used for the diagnosis of congenital fetal arrhythmias. Currently, M-mode echocardiography is the most widely used method. However, good tracings are often difficult to obtain because of unfavorable fetal positions, resulting in long durations of examination. In early gestation, the fetal heart is often too small for clear M-mode echocardiography. Doppler velocity waveforms of the fetal inferior vena cava represent the right atrial activity, whereas those of the aorta reflect ventricular contraction. Because of the proximity of the vessels, it is easy to obtain simultaneous recording in opposite channels of Doppler waveforms from both vessels. A visual relationship between the atrial and ventricular contractions may be clearly established and a diagnosis may be made. The findings of simultaneous pulsed Doppler velocimetry of the fetal aorta and inferior vena cava were assessed in different types of congenital fetal arrhythmia: congenital heart block, premature atrial ectopic contractions, premature ventricular ectopic contractions, and supraventricular tachycardia. The correct diagnosis was made as early as 13 weeks' gestation, showing the application of this method in early pregnancy.

Aorta, Abdominal↗
PubMed1990

Surgical treatment for recurrent ovarian malignancies.

Eighty-nine cases of recurrent ovarian malignancies which had undergone surgical treatment were studied. Debulking surgery is of great value in the treatment of primary ovarian carcinoma, but for recurrent carcinomas success depends upon the pathological type. The 5-year survival rate was 75% for patients with immature teratomas, but only 6.1% for those with epithelial ovarian carcinomas and 3.6% with endodermal sinus tumors. Two cases of recurrent dysgerminoma were both alive and well more than 10 years after treatment. So repeated debulking is worthwhile for recurrent immature teratoma and dysgerminoma, while in cases of epithelial type or endodermal sinus tumors successful debulking surgery should be followed by some new kinds of adjuvant therapy, otherwise only failure will result.

Carcinoma↗