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Biomedical subjects

S S Chang

Publications and source records attributed to S S Chang.

At least 55 records · Page 3Linked to original sources
PubMed1994

Antihypertensive action of geraniin in rats.

The effects of geraniin, one of the ellagitannins purified from the leaves of Sapium sebiferum, on blood pressure were investigated in the spontaneously hypertensive rat (SHR). A single intravenous bolus injection of geraniin into anaesthetized SHRs lowered the arterial mean blood pressure in a dose-dependent manner without affecting the heart rate. A similar action was also observed in the normotensive (WKY) rat that received this compound at a higher dose. Geraniin did not modify the baroflex sensitivity in the phenylephrine-challenged SHR. This tannin reduced the plasma noradrenaline in a dose-dependent fashion which was not influenced by adrenalectomy. Failure of the antagonists, idazoxan and yohimbine for alpha 2-adrenoceptors as well as haloperidol and domperidone for dopamine receptors, to reverse the antihypertensive actions of geraniin ruled out the possible mediation of these receptors. Moreover, geraniin attenuated the pressor responses to exogenous noradrenaline and Bay K 8644 to a similar degree, indicating the direct effect of this compound on vascular activity in rats. These results suggest that geraniin possesses the ability to lower systemic blood pressure through the reduction of noradrenaline release or by direct vasorelaxation.

Adrenalectomy↗
PubMed1993

Inhibitory effect of xylamine on the uptake of [3H]dopamine into isolated striatal synaptosomes of the rats.

The synaptosomal preparations from Wistar rat striata show a Na(+)-dependent, nomifensine-sensitive uptake of [3H]dopamine([3H]DA). Xylamine, a nitrogen mustard, attenuated this uptake of [3H]DA into the synaptosomes (IC50 = 0.2 microM). The dose-dependent reduction of [3H]DA uptake by xylamine indicated competitive kinetics. Action of xylamine was modified if the active transport inhibitor, ouabain or iodoacetate, was also incubated during the pretreatment period or if the content of Na+ in medium was changed. Also, xylamine displaced the binding of [3H]mazindol in a correlative way with the inhibition of [3H]DA uptake. However, the activity of Na+, K(+)-ATPase in synaptosomes was not modified by xylamine at concentrations sufficient to block the uptake of [3H]DA. These findings suggest that xylamine has the ability to compete with the transport of [3H]DA into striatal synaptosomes through an effect on the carrier instead of an action on enzymatic activity.

Animals↗
PubMed1993

Inhibitory effect of octopamine on the release of endogenous acetylcholine from isolated myenteric synaptosomes of guinea-pig.

1. The effect of octopamine on the release of endogenous acetylcholine (ACh) from isolated ileal synaptosomal preparations of guinea-pigs was examined using high pressure liquid chromatography with electrochemical detection. Release of ACh was induced by substance P or by depolarization with high potassium (50 mmol/L) in medium containing atropine, propranolol and naloxone. 2. Octopamine produced a dose-dependent inhibition of substance P-induced ACh release. A similar inhibitory action of octopamine was found in the samples depolarized by high potassium as a reference. 3. The action of octopamine was not reversed by the dopamine receptor antagonists either for the DA-2 subtype, domperidone, or for the DA-1 subtype, SCH23390, or by haloperidol. However, idazoxan and yohimbine antagonized this octopamine-induced inhibition at concentrations sufficient to abolish the action of clonidine. 4. Failure of guanethidine or nomifensine to inhibit octopamine ruled out mediation by noradrenergic neurotransmitters. 5. Octopamine decreased the influx of [45Ca] stimulated by substance P into synaptosomal preparations and this was reversed by idazoxan or yohimbine at concentrations sufficient to block the action of clonidine. 6. Pertussis toxin abolished the inhibitory action of octopamine at a dose high enough to block the action of clonidine. 7. These results indicate that octopamine suppresses the influx of calcium ions into cholinergic nerve terminals of ileal synaptosomes of guinea-pigs via an activation of alpha 2-adrenoceptors coupled with a pertussis toxin-sensitive GTP-binding protein which results in a decrease of ACh release.

Acetylcholine↗
PubMed1993

Characterization of two full-length cDNA sequences encoding for apoproteins of peridinin-chlorophyll a-protein (PCP) complexes.

Characterizations are presented for RNA, 2 cDNA libraries, and 2 full-length cDNA sequences encoding for photosynthetic light-harvesting peridinin-chlorophyll a-protein (PCP) in the dinoflagellate Heterocapsa pygmaea. Subsequent analyses of the PCP system also indicate that (1) it is represented by multiple nuclear encoded genes, (2) a subset of mRNAs encoding for PCP apoproteins are regulated by growth irradiance, (3) PCP preproteins are larger than the mature apoproteins, and (4) PCP cDNA clones sequenced thus far contain a conserved region but are not identical. Results are discussed in the context of photoadaptation in dinoflagellates.

Amino Acid Sequence↗
PubMed1992

Diagnosis of venous leakage by 133Xe corporeal clearance after intracavernous injection of prostaglandin E1 in poorly responding patients.

133Xe corporeal clearance after intracavernous (IC) prostaglandin E1 (PGE-1) injection was assessed in detecting venous leakage (VL) in a group of impotent patients with poor clinical response to PGE-1 injection. 133Xe corporeal washouts were done in the flaccid state and at full erection or at 20 min after the IC injection of 20 micrograms PGE-1 in cases where no full erection occurred in sequence on two separate days. In each case, data were acquired in frame mode after intracorporeal injection on one side of the midline just behind the glans of 0.1 ml, namely, 1-2 mCi (34-74 MBq) 133Xe in saline for 20 min. A time-activity curve was generated from the region of interest (ROI) at the site of injection and a computer routine was used to calculate clearance half-time (T1/2) in min and flow rate (Q) in ml per 100 g tissue per min. The data of 20 patients with equivocal response to IC PGE-1 were analysed. Of them, 14 had venous leakage and six had no vascular impairment (NVI). Venous leakage was proved by Doppler analysis, cavernosography after PGE-1, and/or selective arteriography. Twelve of 14 patients with VL had enhanced 133Xe corporeal clearance after PGE-1 with a significant decrease in T1/2 (mean +/- S.D.) from 115.9 +/- 196.0 to 13.3 +/- 13.4 (P less than 0.05) and increase in Q from 2.1 +/- 2.2 to 7.5 +/- 5.6 (P less than 0.01). In contrast, all six patients with NVI had decreased 133Xe corporeal clearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

A comparison of diagnostic criteria for neuroleptic malignant syndrome.

BACKGROUND: A variety of diagnostic criteria for neuroleptic malignant syndrome (NMS) have been used in clinical studies of this disorder, but it is not known if different criteria consistently identify NMS. This study examines agreement between three frequently used sets of diagnostic criteria in a series of possible NMS episodes. METHOD: All clinically suspected NMS episodes occurring at a large tertiary psychiatric facility during a 6-year period were evaluated by three different sets of diagnostic criteria. Agreement among these criteria was quantified statistically by means of the kappa and intraclass correlation coefficients. RESULTS: The NMS diagnostic criteria examined generally demonstrated only fair agreement with one another in the diagnosis of NMS. Agreement was best among these criteria when the "probable" category was employed. A complex interaction involving both definition and structure of individual diagnostic criteria and designation of criteria as major or minor appears to contribute to these findings. CONCLUSION: The published diagnostic criteria used in this study do not consistently identify NMS episodes and demonstrate different thresholds for assigning this diagnosis. These differences are not due solely to different definitions of individual criteria (e.g., fever). Possible implications of these findings for clinical practice and research are discussed.

Adult↗
PubMed1992

Osteopetrosis.

Explore the source record for details and available documents.

Bone Marrow Transplantation↗
PubMed1991

Reduction of calcium excretion in the stone-forming kidney in unilateral ureteral obstruction.

Thirteen urolithiasis patients with unilateral obstructive uropathy were treated with percutaneous nephrostomy (PCN) either for urinary diversion, endopyelotomy, nephrolithtotmy or chemolysis. After percutaneous nephrostomy, the individual urine volume, creatinine clearance (Ccr), urinary absolute and fractional excretions of sodium, potassium, calcium, magnesium and inorganic phosphate were measured separately in timed urine collections from a pigtail catheter and from the urethra. The data showed that Ccr and the absolute urinary excretions of sodium, potassium, calcium, magnesium and inorganic phosphate were significantly lower in the PCN kidney immediately or 2 days after relief of obstruction. The ratio of total urinary calcium excretion to urinary creatinine excretion in the obstructed kidney was significantly greater than that in the contralateral kidney. The fractional excretions of calcium and magnesium increased as renal function decreased. The results showed that when the total Ccr is below normal, the apparent excretion of urinary calcium will be underestimated. However, when the total Ccr of patients is within normal range, hypercalciuria may be detected adequately and thus favors early implementation of an appropriate therapeutic strategy.

Calcium↗
PubMed1991

Maintenance lithium levels could be lowered: based on Taiwanese and Danish studies.

Twenty-two patients, 8 males and 14 females, who had been lithium-free for at least 1 week were included in this study. All patients took 900 mg of Lithonate at 8:00 a.m. while in a fasting state. A 5 ml blood sample was taken at 9:00 a.m., 10 a.m., 12 noon, 3 p.m., 5 p.m., 11 p.m., and at 9 a.m. and 3 p.m. on the next day. Plasma was separated immediately, and the lithium level was measured by atomic absorption spectrophotometry. The pharmacokinetic parameters were as follows: K12 (microconstant) = 0.3455 +/- 0.5345 (mean +/- SD) h-1; K21 (microconstant) = 0.1691 +/- 0.1242 h-1; K10 (microconstant) = 0.1320 +/- 0.1112 h-1; Vl (volume of distribution of central compartment) = 16.9057 +/- 5.9384 1; Vss (volume of distribution at steady state) = 38.8917 +/- 11.4540 1; V-beta (volume of distribution of elimination phase) = 46.3809 +/- 13.8742 1; alpha (distribution rate constant) = 0.5932 +/- 0.7090; and beta (excretion rate constant) = 0.0361 +/- 0.0141. The mean elimination half-life, AUC (the area under the curve) and clearance were 22.5 +/- 9.9 h (range from 9.6 to 50.4 h), 16.33 +/- 5.52 mmoll-1h (8.69 to 31.81 mmoll-1 h), and 1.65 +/- 0.53 1h-1 (0.76 to 2.28 1h-1) or 28.59 +/- 9.58 ml/kg-1 h-1, respectively. There were no statistically significant differences in beta, AUC and clearance between Taiwanese/Chinese and Danish results. The possibility of lowering the traditional prophylactic therapeutic range of lithium to around 0.5-0.8 mmol/L is supported by the results of this study.

Bipolar Disorder↗
PubMed1991

Experience with Lithostar shock wave lithotripsy for the treatment of upper urinary tract stone.

The experiment of Lithostar, an electromagnetic generator of the second-generation extracorporeal shock wave lithotriptor is presented. From August 2, 1988 to April 4, 1989, 387 treatments in 333 cases were conducted by Lithostar. Among all patients, the overall stone-free rate is 71.9% in which the ureteral stone-free rate (87.7%) is higher than the renal (66.3%) and 19.5% of the patients need additional procedures. This Lithostar proves to be easy in operation, bathless, requires less anesthesia, and may be used in combination with other procedures. It can also make higher average shock number than Dornier HM-3 lithotriptor because of its milder shock wave pressure.

Adolescent↗
PubMed1991

Radionuclide imaging clinical study. Corporeal 133Xe washout for detecting venous leakage in impotence.

A quantitative test, corporeal 133Xe washout, was developed to detect venogenic impotence. Data were acquired in frame mode after intracorporeal injection of 0.1 ml (1-2 mCi or 37-74 MBq) of 133Xe in saline on one side of the midline just behind the glans in the flaccid state for 20 min. A time-activity curve (TAC) was generated from the region of interest (ROI) at the site of injection and a computer routine was then used to calculate clearance half-time (T1/2) in minutes and flow rate (Q) in ml/100 g tissue/min from corporeal 133Xe clearance. The data from 12 controls and 21 patients with venous leakage were analysed. In patients with venogenic impotence, T1/2 (mean +/- S.D.) was greatly increased (24.4 +/- 10.7 min vs 10.7 +/- 4.6 min in controls, P less than 0.005) whereas Q markedly decreased (2.4 +/- 1.3 ml/100 g tissue/min vs 5.4 +/- 2.3 ml/100 g tissue/min in controls, P less than 0.005). The sensitivity and specificity for detecting venous leakage at the optimal threshold of T1/2 equal to 13 min and Q equal to 3.7 ml/100 g tissue/min were 95 and 75%, respectively. The corporeal 133Xe clearance half-time and flow rate are two simple and clinically useful indices for detecting venous leakage.

Adult↗
PubMed1990

Long-term reno-cardiovascular effects of orally administered aconiti tuber in humans.

The reno-cardiovascular effects of Aconiti Tuber were studied. In a controlled, double-blind, and randomized clinical trial, it was found that in 9 months, Aconiti Tuber, after preparation (120 degrees C, 40 min), (1) had no apparent adverse effects, (2) showed positive inotropic, positive chronotropic, and vasodilator effects, (3) increased renal blood flow, and glomerular filtration rate, Na+/Cl-/K+ excretions. The renal function test results could be interpreted as secondary to hemodynamic changes. We conclude that specially prepared Aconiti Tuber may be a promising cardiotonic agent.

Adult↗
PubMed1990

MAO inhibition and clinical response in depressed patients treated with phenelzine.

The authors studied clinical response in 47 depressed inpatients treated with the monoamine oxidase (MAO) inhibitor phenelzine. Improvement on ratings for depression at Week 2 of treatment was correlated with percent MAO inhibition at Week 2 (r = .35, p less than .03), and the modest positive correlation that was found remained after the authors adjusted for the effects of baseline scores on the Hamilton Rating Scale for Depression, dose (mg/kg), and psychosis (partial correlation = .49, p less than .002). Further, the 23 patients ultimately classified as responders had a significantly greater percent MAO inhibition at Week 2 than did the 24 nonresponders (t = 3.02, p less than .005). Thus, the rate of MAO inhibition at Week 2 was significantly correlated with clinical improvement at Week 2 and final response status. These findings could not be explained by other potentially moderating variables such as sex, age, endogenicity, recurrence, and incapacitation.

Adult↗
PubMed1989

The molluscan neuropeptide FMRFamide stimulates the release of [14C]acetylcholine from isolated ileal synaptosomal preparations of guinea-pig.

FMRFamide stimulated, in a dose-dependent manner, the efflux of [14C]acetylcholine (ACh) from isolated synaptosomes of guinea-pig ileum preloaded with labelled choline. Participation of the cholinergic mechanism and/or substance P was ruled out by the finding that antagonists failed to affect the FMRFamide-induced release of ACh. The ACh-releasing action of FMRFamide was negated by the deletion of calcium ion from the bathing medium and it was also abolished by tetrodotoxin. The results obtained suggest that FMRFamide possesses the ability to induce the release of ACh from enteric synaptosomes of guinea-pig.

Acetylcholine↗
PubMed1989

Familial bone marrow monosomy 7. Evidence that the predisposing locus is not on the long arm of chromosome 7.

Loss of expression of a tumor-suppressing gene is an attractive model to explain the cytogenetic and epidemiologic features of cases of myelodysplasia and acute myelogenous leukemia (AML) associated with bone marrow monosomy 7 or partial deletion of the long arm (7q-). We used probes from within the breakpoint region on 7q-chromosomes (7q22-34) that detect restriction fragment length polymorphisms (RFLPs) to investigate three families in which two siblings developed myelodysplasia with monosomy 7. In the first family, probes from the proximal part of this region identified DNA derived from the same maternal chromosome in both leukemias. The RFLPs in these siblings diverged at the more distal J3.11 marker due to a mitotic recombination in one patient, a result that suggested a critical region on 7q proximal to probe J3.11. Detailed RFLP mapping of the implicated region was then performed in two additional unrelated pairs of affected siblings. In these families, DNA derived from different parental chromosome 7s was retained in the leukemic bone marrows of the siblings. We conclude that the familial predisposition to myelodysplasia is not located within a consistently deleted segment on the long arm of chromosome 7. These data provide evidence implicating multiple genetic events in the pathogenesis of myelodysplasia seen in association with bone marrow monosomy 7 or 7q-.

Adolescent↗
PubMed1988

Cerebrospinal fluid and urinary biogenic amines in depressed patients and healthy controls.

The National Institute of Mental Health-Clinical Research Branch Collaborative Study investigated 132 drug-free, severely depressed patients and 80 healthy controls. Forty-five percent of the depressed patients excreted markedly elevated levels of urinary epinephrine (E) and metanephrine (MET), while only 5% of healthy controls did so. Using gaussian mixture distributions, we identified two subgroups of depressed patients: one excreting normal levels and the other excreting high levels of urinary E, MET, norepinephrine, and normetanephrine. Cerebrospinal fluid homovanillic acid levels were low in a subgroup of depressed patients. When analyzed by subgroup, the elevated E + MET group had markedly lower cerebrospinal fluid homovanillic acid levels than controls, whereas depressed patients with normal catecholamine levels did not. Since it has been postulated that there are two subgroups of depressed patients, those with low 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and normal 5-hydroxyindoleacetic acid (5-HIAA) levels and those with normal MHPG levels and low 5-HIAA levels, several analyses were performed to see if such a group could be identified. Our analysis failed to find evidence of a subgroup of depressives with low MHPG and normal 5-HIAA levels or normal MHPG and low 5-HIAA levels.

Biogenic Amines↗