PubMed Health⌕ Search

Biomedical subjects

C R Yang

Publications and source records attributed to C R Yang.

At least 109 records · Page 6Linked to original sources
PubMed1992

Triterpenoidal saponins from Madhuca butyracea.

Two new triterpenoidal saponins, butyrosides A and B, were isolated from the seeds of Madhuca butyracea, along with two known saponins, Mi-saponin A and 16 alpha-hydroxy Mi-saponin A. On the basis of chemical and spectroscopic evidence, the structures of butyrosides A and B were established to be 3-O-beta-D-glucopyranosyl protobassic acid 28-O-beta-D-apiofuranosyl(1----3)-beta-D-xylopyranosyl (----4)-alpha-L-rhamnopyranosyl(1----2)-alpha-L-arabinopyranoside and 3-O-beta-D-glucopyranosyl 16 alpha-hydroxy protobassic acid 28-O-beta-D-apiofuranosyl(1----3)-beta-D-xylopyranosyl (1----4)-alpha-L-rhamnopyranosyl(1----2)-alpha-L-arabinopyranoside , respectively.

Carbohydrate Sequence↗
PubMed1992

Steroid saponins from Polygonatum kingianum.

Four new steroid saponins, kingianosides A-D, were isolated from the rhizome of Polygonatum kingianum, together with two known steroid saponins. On the basis of chemical and spectral evidence, the structures of kingianosides A-D were established as gentrogenin 3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside, gentrogenin 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-fucopyranoside, 26-O-beta-D-glucopyranosyl-22-hydroxy-25(R)-furost-5-en-12-on-3 beta, 22-diol 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside and 26-O-beta-D-glucopyranosyl-22-hydroxy-25(R)-furost-5-en-12-on-3 beta,22-diol 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-fucopyranoside, respectively.

Carbohydrate Sequence↗
PubMed1992

Comparison of effects following the intracorporeal injection of papaverine and prostaglandin E1.

A study group of 240 impotent men receiving intracorporeal injections were divided into 2 groups: the first group received papaverine (60 mg) and the second prostaglandin E1 (PGE1 20 micrograms). The effect of the drugs was evaluated according to the onset of erection, rigidity and the duration of erection; 136 patients were treated with papaverine and 104 with PGE1. The onset of action in these groups was 6.42 +/- 5.39 vs 10.14 +/- 5.41 min; the rigidity score was 3.37 +/- 0.89 vs 3.60 +/- 1.10 and the duration of erection was 49.56 +/- 62.56 vs 63.60 +/- 44.57 min respectively. There was a significant difference in the onset of action (PGE1 was slower than papaverine) and maintenance of erection (longer with PGE1 than with papaverine). Another group of 17 patients received both papaverine and PGE1. The effects of papaverine were better in 4 cases, worse in 5 and equal to PGE1 in 8. This study indicates that compared with papaverine, treatment with PGE1 produces a slower onset of action, a longer duration of erection and fewer side effects.

Adult↗
PubMed1992

Angiotensin II receptor activation depolarizes rat supraoptic neurons in vitro.

Functional studies indicate that hypothalamic magnocellular neurosecretory neurons are a target for angiotensin. The present investigation used intracellular recordings to characterize the nature and type of angiotensin II receptors on rat supraoptic nucleus neurons maintained in superfused hypothalamic explants. Of 68 cells transiently exposed to either Val5- or Ile5-angiotensin II (maximum peak concentration 1-25 microM), 34 responded with a gradual membrane depolarization (1-15 mV) that peaked in 2.2 +/- 0.4 (SD) min and was accompanied by a 17.6 +/- 4.8% reduction of input resistance. Responses persisted (and were actually enhanced) in media containing tetrodotoxin (0.5-1.0 microM) and/or nominally zero calcium, indicating a direct postsynaptic action. In 19 responsive cells, the mean reversal potential for the angiotensin-induced response was -26.4 +/- 2 mV. Bath application of the nonpeptide type-1 angiotensin receptor antagonist DuP753 (5-20 microM) reversibly blocked the angiotensin-induced depolarization in all of 11 cells tested. By contrast, equimolar applications of the type-2 antagonist PD123177 were ineffective in all seven angiotensin-responsive cells tested. These observations provide novel evidence for the existence of functional type-1 receptors on rat supraoptic nucleus neurons. The reversal potential for the angiotensin-induced response suggests mediation through a nonselective cationic conductance.

Angiotensin II↗
PubMed1992

Use of indomethacin in the prophylaxis of ureteral colic following extracorporeal shock wave lithotripsy.

Ureteral obstruction leading to pain seems to be related to an increase of renal prostaglandins (PG). We designed a prospective double-blind, placebo controlled protocol for evaluating the effect of indomethacin, a PG-synthetase inhibitor, in the prophylaxis of ureteral colic following extracorporeal shock wave lithotripsy (ESWL). Sixty patients undergoing ESWL were randomized into two groups, group 1 (study group) received 50 mg indomethacin capsule three times daily and group 2 (control group) received multiple-vitamin tablet three times daily. Twenty-four hours urine samples were collected before and three days after ESWL was performed for PGE2 (predominant renal PG) determination. Subjective pain after ESWL was recorded with pain score (0-10 degrees). Oral codein or pethidine injection were available for relieving pain following ESWL. The pain score, analgesic requirement and urinary PGE2 in pre- and post-ESWL were used to compare the two groups. The pain score was 4.00 +/- 0.25 and 3.00 +/- 0.25 in the control and study groups respectively; it had a statistically significant difference (p < 0.01). In control group, 12 and 14 patients required 23 doses of codein and 18 doses of pethidine. In the study group, three and four patients required five doses of codein and eight doses of pethidine. The difference was statistically significant (p < 0.05). In the control group, the mean pre- and post-ESWL urinary PGE2 was 305 +/- 65.8 and 474 +/- 101 micrograms/24-hr respectively. In the study group, the mean pre- and post-ESWL urinary PGE2 was 289 +/- 60.7 and 186 +/- 26.5 micrograms/24-hr respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Clinical study of Urocit-K: a slow releasing potassium citrate].

Citrate is recognized as one of the inhibitors of urinary stone formation. If the urinary citrate and pH could be elevated by the supply of potassium citrate, the recurrence of stone formation would hopefully be prevented. Urocit-K is a kind of slow releasing preparation of potassium citrate. The pharmacokinetics of Urocit-K is investigated in this study, which included two groups: 1) the hypocitraturia group consisting of twenty patients and 2) the normal volunteer group consisting of ten persons. Urokit-K was administered to patients in 10 mEq doses, t.i.d. for 2 weeks. Comparison of urinary biochemistry was done prior to, and one week after administration of the Urocit-K. In the normal volunteer group, the pharmacokinetics of Urocit-K was determined by urinary pH, K, and citrate. Determinations were made six times a day (every 2-hours for first 8 hours, 7- and 9- hours for the last 16 hours) with Urocit-K for comparison. This study indicated that Urocit-K increases urinary pH, K, and citrate in hypocitraturic patients. In the normal volunteer group, Urocit-K deserves its slow-releasing property shown by a constant increase of urinary pH and K for the first 8 hours; and urinary citrate for almost 24 hours. No apparent complications, such as gastrointestinal upset or cardiopulmonary discomfort were observed. In conclusion, Urocit-K is an excellent preparation of potassium citrate and a good choice for prevention of stone recurrence.

Citrates↗
PubMed1992

[A comparison of transrectal fine needle aspiration and biopsy of prostatic lesion].

Transrectal fine needle aspiration and biopsy were performed on 100 patients with suspicious prostatic lesions using 22 gauge aspiration needles and 18 gauge biopsy needles. These collections were made from January 1990 to June 1991. Sufficient prostate tissue for cytological and histological diagnosis were obtained in 97% (97/100) and 99% (99/100), respectively. Thirty-nine patients (39%) were diagnosed having cancer with an accuracy rate of 89.7% (35/39) by histology and 69.2% (27/39) by cytology. One patient with a normal cytological aspiration was found to have an atypical biopsy, therefore, the biopsy was repeated and the prostate showed adenocarcinoma. Our results indicate that the needle aspiration cytology has a less accurate diagnosis rate than the needle biopsy histology. Fine needle aspiration is a safe and effective outpatient procedure but there is a definite learning curve before its use can be fully exploited. It is important to have experienced urologists and pathologists to perform these aspirations until sufficient experience is accumulated.

Aged↗
PubMed1991

The contribution of basal forebrain to limbic-motor integration and the mediation of motivation to action.

The contribution of hippocampal glutamatergic and VTA dopaminergic inputs to the nucleus accumbens and the role of accumbens--ventral and subpallidal GABAergic pathway in integrating the limbic signals into motor responses via pedunculopontine nucleus were examined with electrophysiological and behavioural techniques. Stimulation of hippocampal input to the accumbens activates GABAergic output to the subpallidal area which leads to suppression of spontaneous firing of subpallidal neurons, while activation of dopamine receptors in the accumbens suppresses GABAergic output to subpallidal area and thus increases the firing of picrotoxin-sensitive ventral pallidal neurons. However, both treatments induced hypermotility suggesting the functional heterogeneity of the ventral and subpallidal areas in "limbic-motor integration". Furthermore, both hippocampal output signals and dopaminergic input to the accumbens descend via ventral and subpallidal areas serially to the pedunculopontine nucleus, the region of the mesencephalic locomotor region. In addition, a parallel ascending pathway from the subpallidal area to the mediodorsal nucleus, and subsequently to the medial prefrontal cortex, probably mediates behaviour, e.g. food hoarding, that requires higher cognitive processing.

Animals↗
PubMed1991

Triterpenes from Mucuna birdwoodiana.

Methanolic extracts of the stalks of Mucuna birdwoodiana on acid hydrolysis and subsequent methylation with diazomethane provided four triterpene sapogenols. On the other hand, investigation of glycosides after methylation of the same extract led to the isolation of four triterpene glycosides. On the basis of chemical and spectral evidence, their structures were characterized as methyl asiatate, methyl maslinate, two new sapogenols, methyl 1 beta,2 alpha,3 beta,23-tetrahydroxyolean-12-en 28-oate (mucunagenin a), its urs-12-en isomer (mucunagenin b), 3-O-(6-O-methyl-beta-D-glucuronopyranosyl) methyl asiatate 3-O-[alpha-L-arabinopyranosyl(1----2)]-6-O-methyl-beta-D-glucur onopyranosyl methyl maslinate, 3-O-[alpha-L-arabinopyranosyl(1----2)]-6-O-methyl-beta-D-glucur onopyranosyl methyl asiatate and 3-O-(6-O-methyl-beta-D-glucuronopyranosyl) asiatic acid 28-O-beta-D-glucopyranoside.

Carbohydrate Sequence↗
PubMed1991

Brandioside, a phenylpropanoid glycoside from Brandisia hancei.

A new phenylpropanoid glycoside, brandioside, was isolated from Brandisia hancei. Its structure, [beta-(3',4'-dihydroxylphenyl)-ethyl]-(2-O-acetyl)-(3,6-O-di-alpha -L-rhamnopyranosyl)-(4-O-caffeoyl)-beta-D-glucopyranoside, was established by chemical and spectroscopic methods.

Acetylation↗
PubMed1991

Evaluation of penile dorsal arteries and deep arteries in arteriogenic impotence.

The dorsal and deep arteries are the 2 main blood supplies to the penis. High resolution ultrasonography was used to evaluate the role of these 2 sets of arteries in erection. A total of 44 impotent patients entered this study. We used duplex ultrasonography (Diasonic DRF/400) to assess the role of the dorsal and deep arteries in arteriogenic and nonarteriogenic impotent patients. Vascular velocity, as well as the change in diameter, was recorded before and after an intracavernous injection of 60 mg. papaverine. In the arteriogenic impotence group (28 patients, 63.6%), the velocity increments were 37.1 +/- 23.6 (right side) and 35.4 +/- 17.5 (left side) cm. per second in the dorsal arteries, and 8.3 +/- 5.9 (right side) and 12.6 +/- 5.6 (left side) cm. per second in the deep arteries. In the nonarteriogenic group (16 patients, 36.4%) the velocity increments were 46.5 +/- 25.2 and 41.1 +/- 22.4, respectively, in the dorsal arteries, and 37.3 +/- 16.5 and 37.5 +/- 15.8, respectively, in the deep arteries. Comparison of the velocity increments between the arteriogenic and nonarteriogenic groups revealed no difference in the dorsal arteries (p greater than 0.1) but a significant difference was noted in the deep arteries (p less than 0.01). Similar findings were also encountered when the velocities and diameter increments were compared. This study indicates that the deep arteries have an important role in erectile response, while the dorsal arteries are less important.

Adult↗
PubMed1991

Dopamine D2 receptor activation depolarizes rat supraoptic neurones in hypothalamic explants.

1. Intracellular current and voltage clamp recordings were obtained from rat supraoptic nucleus neurones in superfused hypothalamic explants in order to evaluate their response to dopamine and to D1 and D2 agonists. 2. With one exception, exposure to dopamine (10-200 microM) depolarized supraoptic neurones. When tested for an effect on twenty-one spontaneously active supraoptic neurones, dopamine enhanced the firing of all eleven continuous-firing (possibly oxytocin-secreting) neurones and prolonged the burst in all ten phasic-firing (vasopressin-secreting) neurones. 3. In sixty-seven of sixty-eight neurones where current injection was used to maintain membrane potential below threshold for action potential generation, current clamp data revealed that exposure to dopamine (10-200 microM) was followed in 10-17 s by a gradual 3-7 mV membrane depolarization that lasted for 4-15 min and was accompanied by a 12-23% reduction in input resistance. Exposure to quinpirole, a D2 agonist (10-200 microM), induced a similar response with comparable onset, duration and change in input resistance. In contrast, tests on sixteen cells indicated little or no response to a D1 agonist SKF38393. 4. Under voltage clamp, dopamine was noted to induce an inward current, accompanied by a 7.5-40% increase in membrane conductance over the corresponding time course. 5. Voltage-current plots for dopamine-induced depolarizations were linear in the range -50 to -110 mV. Dopamine and quinpirole depolarizations had extrapolated mean reversal potentials of -25 +/- 10 mV (mean +/- S.D.) and -20 +/- 15 mV respectively. This approximated the mean reversal potential of -20 +/- 8 mV measured from the dopamine-induced inward current using single-electrode voltage clamp. 6. The actions of dopamine were selectively antagonized by two D2 receptor antagonists, sulpiride and spiperone, but neither influenced membrane depolarizations induced by equimolar concentrations of noradrenaline. Dopamine-induced depolarizations also persisted following selective blockade of alpha 1-adrenergic receptors by prazosin; under these conditions, noradrenaline induced membrane hyperpolarization. 7. Following complete substitution of external Na+ with Tris, the reversal potential for the dopamine-induced response was shifted to -70 +/- 9.8 mV. This value was consistently less negative than the estimated potassium equilibrium potential. 8. The depolarization action of dopamine persisted in media containing tetrodotoxin and with an external calcium concentration ([Ca2+]o) of 0 mM-Ca2+ with 6 mM-Mg2+ or Mn2+, but was abolished following intracellular injection of [1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a Ca2+ chelator.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Histopathological change of corpora cavernosa after long-term intracavernous injection.

Repeated intracavernous injections in healthy monkeys with 2 kinds of vasoactive agents [papaverine and prostaglandin E1 (PGE1) 3 monkeys each] and normal saline (2 monkeys) were conducted in this study. The purpose was to observe the effect of long-term injection on histopathological changes of the cavernous tissue, as well as the change in drug sensitivity (dosage dependence). Different dosages of the same volume (double, single and half dose) of these 3 agents were injected, twice weekly, 10 times alternatively, with rigidity and maintenance of erection recorded. After long-term injection (papaverine group: 37, 60, 60 times; PGE1 group: 26, 60, 60 times; normal saline group: 60, 60 times), all monkeys were sacrificed and the penises were collected for light-microscopic (LM) and electron-microscopic (EM) examinations. Dose-dependent response with reversed drug sensitivity was found in the papaverine group, but only elongation to tumescence was found in the PGE1 group, even with double dosage (probably because of scarce PGE1 receptors in monkey's penile tissue). Histopathologically, mild to moderate fibrotic changes and distortion of normal architecture were predominant findings in LM while aggregation of mitochondria, irregular shape or atrophy of cells were obvious in EM observation in the papaverine group. On the other hand, limited fibrosis with preservation of corpora cavernosa and hypertrophy of smooth muscle were noted in the PGE1 group. This study indicated that less histopathological change occurred in the PGE1 group after long-term intracavernous injection.

Alprostadil↗
PubMed1991

Renal angiomyolipoma: experience of 23 patients.

We reported 29 kidneys with angiomyolipoma in 23 patients (14 women and 9 men). One of these cases was associated with tuberous sclerosis. Their age ranged from 20 to 82 years (mean 48.9). Six patients had bilateral renal involvement and 7 had multiple lesions in one kidney. Synchronous renal tumors were noted in three patients. One patient was associated with renal cell carcinoma, and the other two patients with transitional cell carcinoma. Nineteen tumors in 16 patients were larger than 4 cm. Among them 93.8% (15/16 patients) were symptomatic and tumor hemorrhage was found in 57.9% (11/19 kidneys). Of these patients, 17 renal units underwent surgical intervention (including 8 total nephrectomy, 7 partial nephrectomy and 2 enucleation of tumor). Preoperative diagnosis was made in 82.4% (14/17) with combined imaging of sonogram and CT scan. One patient received embolization only. There were two mortalities: one patient with tumor rupture who received emergent nephrectomy but died of irreversible hypovolemic shock, and the other with tuberous sclerosis and pulmonary fibrosis who received embolization for spontaneous rupture of tumor but expired due to respiratory failure. Among nine patients receiving renal preserving operation, the post-operative effective renal plasma flow of the affected kidneys ranged from 96 to 184 ml/min (mean 131.7 ml/min). There was no evidence of recurrence during a mean followup of 2.6 years. Eight asymptomatic patients with 9 renal masses had incidental angiomyolipoma and did not undergo exploration. We did not note any progression of the lesions in the cases under observation for a mean followup of 2.6 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Quantification of acetabular coverage in normal adult].

Quantification of acetabular coverage is important and can be expressed by superimposition of cartilage tracings on the maximum cross-sectional area of the femoral head. A practical Autolisp program on PC AutoCAD has been developed by us to quantify the acetabular coverage through numerical expression of the images of computed tomography. Thirty adults (60 hips) with normal center-edge angle and acetabular index in plain X ray were randomly selected for serial drops. These slices were prepared with a fixed coordination and in continuous sections of 5 mm in thickness. The contours of the cartilage of each section were digitized into a PC computer and processed by AutoCAD programs to quantify and characterize the acetabular coverage of normal and dysplastic adult hips. We found that a total coverage ratio of greater than 80%, an anterior coverage ratio of greater than 75% and a posterior coverage ratio of greater than 80% can be categorized in a normal group. Polar edge distance is a good indicator for the evaluation of preoperative and postoperative coverage conditions. For standardization and evaluation of acetabular coverage, the most suitable parameters are the total coverage ratio, anterior coverage ratio, posterior coverage ratio and polar edge distance. However, medial coverage and lateral coverage ratios are indispensable in cases of dysplastic hip because variations between them are so great that acetabuloplasty may be impossible. This program can also be used to classify precisely the type of dysplastic hip.

Acetabulum↗