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Biomedical subjects

L Chiang

Publications and source records attributed to L Chiang.

27 records · Page 2Linked to original sources
PubMed1984

The nature of the increased sensitivity to injected GTP of the sodium efflux in barnacle muscle fibers pre-exposed to aldosterone.

A study has been made of the increased sensitivity to injected GTP of the sodium efflux in barnacle muscle fibers pre-exposed to aldosterone and of the problem whether or not aldosterone acts by raising the internal ATP level. The results indicate that increased sensitivity to injected GTP develops fully some 8 hr following external application of 10(-6) M aldosterone. Neither actinomycin D nor cycloheximide abolishes this extrasensitivity. This is also true of colchicine and cytochalasin B. The magnitude of the sustained response to injected "dialyzed" cholera toxin or cAMP-protein kinase catalytic subunit is practically the same as that of unexposed fibers. Internal ATP levels in pre-exposed fibers are higher than in unexposed fibers, even in the presence of cycloheximide. Injection of ADP (0.1 M) raises the ATP levels and reduces the ArP levels, more so in unexposed fibers. The suggestion is made that extrasensitivity of pre-exposed fibers to injected guanine nucleotides represents a post-translational phenomenon which might involve delay in the reassociation of R2 with C (of cAMP-PK).

Aldosterone↗
PubMed1983

Some quantitative aspects of myoplasmic ATPMg and total internal ATP and ArP levels in resting barnacle muscle fibres.

1. Flash height recorded following the injection of firefly into the external calibration medium depends on the concentration of K-glutamate used, e.g. 120 mM K glutamate reduces flash height by approximately 20 percent. 2. Suspending the fibre in air instead of artificial sea water (ASW) or replacement of NaCl in the bathing medium with Na-glutamate fails to alter flash height. 3. Firefly preparations from DuPont, Packard and SAI give similar myoplasmic ATPMg values viz. 1.1 mM. 4. Analysis of 36 fibres shows the following: myoplasmic ATP = 1.03 +/- 0.06 mM; total ATP (firefly method) = 5.26 +/- 0.12 mmol/kg water; total ATP (enzymic fluorimetry) = 6.27 +/- 0.13 mmol/kg water and ArP = 20.76 +/- 0.59 mmol/kg water. 5. Measurement of ATPMg in samples of myoplasmic aspirate gives a value that is greater than that obtained in situ. 6. Iodoacetate, whether applied externally or internally, reduces resting luminescence in a dose-dependent manner. It also reduces myoplasmic ATP and total ATP. 7. 2-Deoxy-d-glucose fails to reduce myoplasmic ATP but reduces total ATP. 8. Diethylpyrocarbonate, whether applied externally or internally, reduces myoplasmic ATP. It also causes a slow decline in ArP but little change in total ATP. 9. Injection of L-arginine causes a fall in resting luminescence in some fibres while in others it causes a prompt transitory rise. Injection of L-arginine also causes a fall in total ATP. 10. Collectively, these results suggest that the immediate buffering system in the myoplasm is ArP and that ATP supplied by glycolysis lies in a compartment, presumably the interfibrillar space, which is inaccessible to injected firefly.

Adenosine Triphosphate↗
PubMed1982

Gastricsin and cathepsin D in normal and hypertrophic human prostates.

The relative contents of gastricsinogen, the inactive zymogen precursor of gastric gastricsin (EC 3.4.23.3), and cathepsin D (EC 3.4.23.5) in normal and benign hyperplasia of the prostate gland have been determined. Gastricsinogen levels are significantly lower (0.116 +/- 0.02 U/gm. wet tissue) in the hyperplastic than in normal prostates (0.65 +/- 0.06 U/gm.). Conversely, cathepsin D levels are higher in the diseased (0.705 +/- 0.17 U/gm.) as opposed to normal prostatic tissue (0.39 +/- 0.12 U/gm.). The average gastricsin-cathepsin D differences between the 2 tissues (0.26 +/- 0.025 for normal prostates and -0.59 +/- 0.057 SEM for hyperplastic tissue) are also significantly different (p less than 0.001). It is suggested that the simple determination of these 2 acid proteinases in prostate homogenates could be used as alternative and complementary marker enzymes for the study of the physiopathologic status of the prostate gland.

Acid Phosphatase↗
PubMed1978

Partial characterization of pepsins and gastricsins and their zymogens from human and toad gastric mucosae.

1. Three zymogens have been isolated from human gastric mucosae and two from the stomachs of the toad Caudiverbera caudiverbera. 2. Human zymogens I and III were immunologically related and cross-reacted with antisera prepared against porcine pepsinogen. The third, (II), showed no cross-reactivity. 3. Human zymogens I and III and toad zymogen ZII gave rise to two human pepsins and to a pepsin-like enzyme, respectively. 4. Human zymogen II (gastricsinogen) and toad zymogen ZI gave rise to human gastricsin and to a gastricsin-like enzyme respectively. 5. The toad enzymes showed much greater stability at neutral and alkaline pH values than the human enzymes.

Animals↗
PubMedDate not supplied

Predictors of medication prescription in nursing homes.

OBJECTIVES: To identify patient characteristics associated with higher numbers of prescribed drugs or risk of receiving one or more inappropriate medications. DESIGN: A cross-sectional survey using chart reviews. PARTICIPANTS: A total of 414 long-stay residents of 20 nursing homes in three states MEASUREMENTS: Current medication orders, sociodemographic information, and diagnoses and health status information as indicated by the MDS. The number of routine, total, and inappropriate medications were tabulated. RESULTS: Higher numbers of medications were associated with higher total numbers of diseases. In addition, several diseases (congestive heart failure, hypertension, depression, anxiety, and diabetes) were associated with higher numbers of medications even after controlling for total disease burden. Cognitive impairment was associated with fewer medications after controlling for total number of diseases. Advanced age also attenuated the effect of disease burden on the number of total and routine medications. The only independent predictor of more inappropriate medications was higher numbers of routine medications. CONCLUSION: Several specific disease states predispose patients to prescription of higher numbers of medication, and, these patients must be managed more carefully to prevent adverse drug-drug or drug-disease interactions. Why patients with compromised cognitive status receive fewer medications requires further study.

Journal Article↗