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Biomedical subjects

M C Lin

Publications and source records attributed to M C Lin.

At least 163 records · Page 9Linked to original sources
PubMed1994

Effects of an oral prostaglandin E1 agonist on blood pressure and its determinants in essential hypertension.

Arachidonic acid metabolites such as prostaglandins of the E series have well-documented effects on blood pressure (BP). Recently, a stable analogue of prostaglandin E1 (misoprostol) became available for oral use in humans, being primarily indicated for prevention of peptic disease induced by cyclo-oxygenase inhibitors. We hypothesised that misoprostol would exert antihypertensive actions and therefore performed a randomised, placebo-controlled clinical trial in 15 essential hypertensives to characterise the effects of a 400 micrograms oral dose of misoprostol on BP and its haemodynamic, autonomic and biochemical determinants. There was a modest (from 105.3 +/- 2.7 to 101.9 +/- 2.7 mmHg, P = 0.006) decrease in mean arterial pressure 20 minutes after the dose, accompanied by a decrease in systemic vascular resistance and a compensatory rise in cardiac output and heart rate. Baroreflex gain was unaltered by misoprostol, as were plasma renin activity, catecholamines and chromogranin A. Even this transient antihypertensive effect was abolished by cyclooxygenase inhibitor pretreatment. We conclude that oral misoprostol exerts a modest but transient antihypertensive effect that is unlikely to be of either therapeutic benefit or concern in essential hypertension.

Administration, Oral↗
PubMed1993

Testosterone down-regulates the levels of androgen receptor mRNA in smooth muscle cells from the rat corpora cavernosa via aromatization to estrogens.

Androgens down-regulate the levels of androgen receptors (AR) and AR mRNA in the penis and prostate of castrated rats, and are assumed to cause their decrease during sexual maturation in the penile smooth muscle of intact rats. In order to determine whether these effects occur directly at the target cell level, and to what extent they are due to testosterone (T) or to their metabolites, we have measured AR mRNA in cultures of smooth muscle cells from the adult rat corpora cavernosa treated in vitro with sex steroids. T at high concentrations (100 nM) acted like dihydrotestosterone (DHT) in increasing moderately the levels of AR mRNA in both proliferating and contact-inhibited cells. However, when conversion of T to DHT was blocked by the 5-alpha reductase inhibitor finasteride, the levels of AR mRNA were considerably down-regulated by T (10-500 nM), particularly in the contact-inhibited cells. Finasteride by itself was inactive. These effects in both types of cultures were inhibited by platelet derived growth factor (PDGF) (20 ng/ml), a growth factor that up-regulates AR mRNA levels, and by fadrozole (100 nM), an aromatase inhibitor of the T/estrogen conversion. Estradiol (50 nM) was even more potent than T in decreasing AR mRNA levels. With the exception of PDGF none of the treatments affected significantly cell growth, as measured by DNA synthesis and content. Our results indicate that it is possible to modulate in vitro AR mRNA levels in the penile smooth muscle cells, and that under normal conditions DHT and T act as moderate up-regulators. When DHT formation is inhibited, the aromatization pathway of T to estradiol will prevail and induce a pronounced down-regulation of AR mRNA levels. We assume that the in vivo AR down-regulation in the penile smooth muscle by androgens is an indirect effect mediated by a paracrine or endocrine mechanism elicited in another tissue.

Animals↗
PubMed1993

Scrotal temperature in spinal cord injury.

Twenty-five spinal cord-injured (SCI) males and 25 normal volunteers were studied for their scrotal and thigh temperatures by using contact liquid crystal thermography. The initial temperature was recorded after transfer and disrobing which took about 2 minutes. Later temperature was recorded 10 minutes after exposing the genitalia to room air (20-22 degrees C). The initial scrotal and thigh temperatures of SCI subjects were significantly higher than those of normal volunteers (32.8 +/- 0.8 degrees C v 31.6 +/- 0.4 degrees C; 32.9 +/- 0.8 degrees C v 31.7 +/- 0.4 degrees C, respectively, P < 0.001), although their rectal temperatures were not different. The scrotal and thigh hyperthermia of SCI subjects disappeared after 10 minutes of exposure to room air. There was no significant difference between scrotal and thigh temperatures in either the SCI subjects or the normal volunteers in the later temperature reading. Sitting in a wheelchair for 2 hours results in an increase of average 0.8 degrees C of scrotal and thigh temperature in five normal volunteers. Our study suggests that scrotal hyperthermia of SCI subjects is mainly the result of local factors such as a prolonged sitting position, adduction of the thighs, the cushion's insulating effect and infrequent movement of the buttocks. Adequate ventilation of the scrotal area can overcome the impaired scrotal heat dissipation of SCI subjects. Liquid crystal thermography is a useful, noninvasive method for detecting hyperthermia in SCI subjects.

Adolescent↗
PubMed1993

Timed photoaffinity labeling and characterization of bile acid binding and transport proteins in rat ileum.

Rat ileal enterocytes were radiolabeled by flash photolysis with a photolabile derivative of taurocholate (7,7-azo-[3H]TC) and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Maximal labeling of the bile acid binding proteins (BABPs) was achieved between 15 and 90 s. When enterocytes were pulsed with 7,7-azo-[3H]TC for 2 min, and then 0.5 mM TC was added to chase the radiolabel, the radioactivity in the BABPs was displaced by 50% after 2 min. The 99-kDa brush-border membrane (BBM) protein had the highest initial labeling rate, followed by 43-kDa actin, 35- and 14-kDa cytosolic proteins, 54-kDa basolateral membrane (BLM) protein, 59-kDa BLM-associated protein, and 20-kDa microsomal protein. When a mixed microsomal and cytosolic fraction was photolabeled with 7,7-azo-[3H]TC and then separated, the 20-kDa microsomal protein was labeled. However, if the microsomal fraction alone was photolabeled, the 20-kDa protein was not labeled, suggesting this protein required a cytosolic cofactor for labeling. Using Triton X-114 phase separation and EDTA extraction, the BABPs were separated into amphiphilic integral membrane proteins (99- and 54-kDa proteins) and hydrophilic proteins (14-, 35-, 43-, and 59-kDa proteins). From these data, a model is proposed for transcellular bile acid transport in rat ileal enterocytes.

Affinity Labels↗
PubMed1993

Acute urinary retention in two patients with imperforate hymen.

Acute urinary retention in two adolescent girls with hematometrocolpos caused by imperforate hymen are reported. The accumulation of the menstrual blood in the vagina and uterus may form a mechanical effect on the urethra and bladder and lead to the obstructive urinary symptoms. Hymenotomy created individually by CO2 laser and cruciate incision was performed. The two patients were discharged on the same day after operation and made an uneventful recovery.

Acute Disease↗
PubMed1992

Clinical analysis of surgical treatment for tuboovarian abscess.

The role of copious irrigation and drainage in the treatment of tuboovarian abscess (TOA) is crucial, especially for the patients who want to remain fertile. Some have used vaginal drainage via posterior colpotomy for patients with TOA, whereas others preferred irrigation using large-bore drains. In this study, we reported 31 cases of TOA. We found that for women who want to conceive again the best method of treatment is conservative surgery plus low pressure sump tube drainage.

Abscess↗
PubMed1992

Measurement of viscosity of human semen with a rotational viscometer.

The viscosity of 130 human seminal plasma samples was studied with a rotational viscometer instead of by the traditional subjective rating method. The average seminal viscosity one hour after ejaculation was 9.35 +/- 0.99 centipoise (cps), which was statistically identical to that in the third hour (8.63 +/- 0.77 cps). Seminal viscosity showed a significant negative correlation with the percentage of motile sperm (p < 0.05); however, no significant correlation between seminal viscosity and sperm concentration could be found (r = -0.15, p = 0.098). The seminal viscosity of the oligoasthenospermic group was significantly higher than that of the normospermic group (p < 0.01); there was also a trend towards higher viscosity in the semen of asthenospermia and oligospermia when compared with the normospermic group. It is concluded that seminal viscosity may be higher in cases of poor-quality semen; however, sperm motility and concentration are not the sole determinants of viscosity. Determining the seminal viscosity with this rapid, objective and quantitative method is valuable in identifying and treating the subgroup of infertile men with viscid semen.

Humans↗
PubMed1992

Neurenteric cyst at craniocervical junction: report of a case.

The authors report a rare case of neurenteric cyst at the foramen magnum presenting with a central cord syndrome and dysfunction of the lower cranial nerves. A magnetic resonance imaging study showed a cystic lesion over the lower medulla oblongata and C1-2 spinal cord. Differentiation between a neurenteric cyst and an epidermoid cyst was difficult. Successful total removal of the cyst was performed. The lesion consisted of an enteric cyst lined with a mucus-secreting columnar epithelium, containing highly proteinaceous supernatant and thick mucus deposit. The patient recovered dramatically after surgery.

Adult↗
PubMed1991

Effect of antiserum to a 99 kDa polypeptide on the uptake of taurocholic acid by rat ileal brush border membrane vesicles.

A 99 kDa polypeptide in rat ileal brush border membrane (BBM), regarded as a component of the active bile acid transport system on account of photoaffinity labeling, has been purified by affinity chromatography and preparative gel electrophoresis and utilized as an immunogen for raising polyclonal antibody. Immune serum, but not preimmune serum, specifically recognized a single band of 99 kDa protein on immunoblots of ileal and renal BBM. In contrast, no reactivity was observed with proteins in jejunal BBM. This polyclonal antibody, compared with preimmune serum and anticytosolic bile acid binding protein (14 kDa) serum, significantly inhibited the Na+ dependent uptake of [3H] taurocholate by BBM vesicles (p less than 0.01). [14C] D-glucose uptake by BBM vesicles was not influenced by the immune serum (p less than 0.01). Thus, these studies provide further support for the specific role of a 99 kDa protein in ileal BBM bile acid transport.

Animals↗
PubMed1991

Characterization of a novel 14 kDa bile acid-binding protein from rat ileal cytosol.

A 14 kDa polypeptide in rat ileal cytosol has been identified as the major intestinal cytosolic bile acid-binding protein (I-BABP) by photoaffinity labeling with the radiolabeled 7,7-azo derivative of taurocholate (7,7-azo-TC). To further characterize I-BABP, the protein was purified by lysylglycocholate Sepharose 4B affinity and DE-52 anion-exchange chromatography. The purified I-BABP contained a single 14 kDa band on SDS-PAGE. The 14 kDa protein showed a 26-fold increase in binding affinity for [3H]7,7-azo-TC compared to cytosolic protein. Immunoblotting of protein fractions separated by affinity chromatography showed that neither liver fatty acid binding protein (L-FABP) nor intestinal fatty acid binding protein (I-FABP) bind to the affinity column and that the 14 kDa protein which bound to the column and was subsequently eluted with detergent did not cross-react with anti-L-FABP or anti-I-FABP. The 14 kDa protein labeled with [3H]7,7-azo-TC was radioimmunoprecipitated from cytosol by rabbit antiserum raised against purified I-BABP. I-BABP was shown to have a blocked N-terminus; however, its mixed internal sequence generated from cyanogen bromide-cleaved protein and amino acid composition indicated that it was related to (although clearly distinct from) both I-FABP and L-FABP. These studies have isolated a 14 kDa bile acid-binding protein from rat ileal cytosol which is immunologically and biochemically distinct from I-FABP and L-FABP.

Amino Acid Sequence↗
PubMed1991

Identification of the 14 kDa bile acid transport protein of rat ileal cytosol as gastrotropin.

The 14 kDa bile acid binding protein of rat ileal cytosol (I-BABP), previously shown to be the major intracellular transporter of bile acids in enterocytes, was purified by affinity chromatography and gel electrophoresis. Enzymatic digestion of I-BABP which had been electroblotted to nitrocellulose led to the recovery and sequence analysis of four peptides representing 47 residues of sequence (approximately 35% of the full sequence). All the peptide sequences displayed high levels of identity (greater than 60%) and homology (greater than 80%) to the sequences of porcine and canine gastrotropin. This high level of homology together with other features of I-BABP identify it as rat gastrotropin, establishing gastrotropin as the major intracellular bile acid carrier of rat enterocytes.

Amino Acid Sequence↗
PubMed1991

Heat treatment induces an increase in intracellular cyclic AMP content in human epidermoid A-431 cells.

The basal level of intracellular cyclic AMP (cAMPi) in A-431 cells incubated at 37 degrees C in Na(+)-containing Hanks solution is 2086 +/- 139 fmol/10(6) cells. When cells are exposed to 45 degrees C for 10 min, cAMPi increases by 40 +/- 4%, and then returns to basal levels within 30 min. Incubating cells in Ca(2+)-free or Mg(2+)-free Hanks solution has no effect on the heat-induced increase in cAMPi, but the increase is inhibited by acid-loading cells to intracellular pH 7.0 or 6.8. In unheated cells, cAMPi increases by 16 +/- 8%, 53 +/- 7%, or 39 +/- 8%, when incubated with isobutyl-1-methylxanthine (1 mM), Ro 20-1724 (0.5 mM), or theophylline (1 mM) respectively. However, heat treatment further elevates cAMPi in cells treated with phosphodiesterase inhibitors, indicating that heat treatment and phosphodiesterase inhibitors elevate cAMPi by a different pathway(s). Heat treatment increases adenylate cyclase activity 2.5-fold. When forskolin (150 microM), an adenylate cyclase stimulator, is applied to cells, the basal cAMPi increases 28 +/- 6-fold compared with controls. Subsequent heating of these cells lowers cAMPi levels to 7.0 +/- 0.5 times that in control cells. This decrease is prevented by pretreatment with pertussis toxin (30 ng/ml, 24 h), suggesting that G-proteins are involved in the process of heat-induced cAMPi increase. 2-Deoxy-D-glucose (10 mM), NaN3 (10 mM) and 2,4-dinitrophenol (1 mM) also increase cAMPi in A-431 cells. However, application of these metabolic inhibitors to cells before heat treatment does not result in cAMPi levels greater than that observed in cells with heat alone. Similar observations are obtained in heat-treated cells previously exposed to adenosine, but not to AMP or ADP. These data are the first to suggest that thermally induced increase in cAMPi is due to a combination of activation of adenylate cyclase and G-proteins, and an increase in adenosine owing to ATP breakdown caused by hyperthermia.

Adenosine Triphosphate↗
PubMed1991

The relationship between systolic anterior motion of the mitral valve and the left ventricular outflow tract Doppler in hypertrophic cardiomyopathy.

In an attempt to investigate the role of left ventricular blood outflow in the generation of systolic anterior motion (SAM) of the mitral valve in patients with hypertrophic cardiomyopathy, we precisely analyzed the temporal relation of SAM and the left ventricular outflow tract (LVOT) systolic Doppler events obtained at the maximal mitral-septal apposition or equivalent area in eight patients with severe SAM, in five patients with mild/moderate SAM, and in seven patients with no SAM, using M-mode and pulsed Doppler echocardiography; the results were compared with those in 10 normal subjects. In all 13 patients with SAM, the timing of SAM generation corresponded to the LVOT Doppler events either between the onset of SAM and the onset of Doppler (r = 0.834, p less than 0.0001) or between the peak of SAM and the peak of Doppler (r = 0.836, p less than 0.0001). The excursion rate of the development of SAM showed a correlation with the LVOT blood outflow acceleration (r = 0.828, p less than 0.0001). The timing of SAM resolution also correlated with the Doppler events, either between the offset of SAM and the offset of Doppler (r = 0.795, p less than 0.001) or the end of SAM and the end of Doppler (r = 0.859, p less than 0.0001). The LVOT blood outflow deceleration showed a correlation with the regression rate of SAM (r = 0.668, p less than 0.013). The LVOT blood outflow acceleration was significantly higher in patients with severe SAM than in patients with mild/moderate SAM or no SAM. This study suggests that the high LVOT blood outflow acceleration in early systole possibly plays an important part in the generation of the Bernoulli pressure drop and results in anterior motion of the mitral valve. At mid-systole, a drag force and/or suction effect of pressure drop produced by continuous outflow blood may sustain the anterior motion of the mitral valve. At late systole, as the blood flow decelerates, the regression of SAM then occurs.

Cardiomyopathy, Hypertrophic↗
PubMed1991

Potential diagnosis of hemodynamic abnormalities in patent ductus arteriosus by cine magnetic resonance imaging.

Cine magnetic resonance imaging was performed in 11 patients with communication between systemic and pulmonary circulation. In five patients with uncomplicated patent ductus arteriosus (PDA), ductus arteriosus was delineated by a persistent band of low signal intensity, whereas in two patients who also had severe pulmonary hypertension the signal intensity was varied. Two separate low signal intensities in the main pulmonary artery and the descending aorta were each uniformly recorded in the five patients with uncomplicated PDA, consistent with continuous left-to-right shunt and turbulent flow acceleration, respectively. In one of the patients with severe pulmonary hypertension but not Eisenmenger's syndrome, the areas of low signal intensity from left-to-right shunt and turbulent flow acceleration diminished. In the patient with Eisenmenger's PDA the right-to-left shunt was also characterized by an area of low signal intensity but with a reversal in direction. Cine MR imaging has the potential to be a noninvasive and supplemental method for evaluating PDA.

Adolescent↗
PubMed1991

Hepatic coccidiosis in the goat.

Coccidial oocysts were seen in the bile from five goats infected with coccidia either naturally or artificially. The oocysts measured on average 21.3 by 18.3 microns and resembled those of Eimeria ninakohlyakimovae. Livers and gall bladders of infected animals showed various degrees of histopathological changes. In the worst case, bile had a thick consistency and contained blood and necrotic debris. Apart from those in the bile, oocysts were seen in liver smears and in the centrilobular vein in two histological sections. Forms resembling meronts and measuring on average 200 by 147 microns were seen in sections of bile duct.

Animals↗
PubMed1991

Effects on renal excretion in rats after injection of bile extracts from some fresh-water fish.

Bile acid extracts were prepared from grass carp, bighead, common carp, milk fish and tilapia. Injection of the fish bile extracts (3.6 mg/kg, i.v.) into rats increased renal excretion of water, sodium and potassium; decreased blood pressure; and hemolyzed RBCs. The diuretic, natriuretic, hypotensive and hemolytic actions of the bile extracts were stronger in grass carp, bighead and common carp, moderate in milk fish, and weakest in tilapia.

Animals↗