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Biomedical subjects

C F Chen

Publications and source records attributed to C F Chen.

At least 325 records · Page 18Linked to original sources
PubMed1987

An instrument using variation of resistance to aid in needle tip insertion in epidural block in monkeys.

A new method is proposed to detect the entrance of a needle into the epidural space. Measuring the changes in electric resistance during the insertion of the needle through different tissues in the interspinal space can help anesthesiologists judge whether and when the needle has entered the epidural space. This preliminary, animal study showed that the proposed method performed quite satisfactorily. The electric resistance of the tissues in the interspinal space varied from 1.57 +/- 1.22 k omega to 2.93 +/- 1.14 k omega, and the resistance of the epidural space varied from 9.00 +/- 1.12 k omega to 14.64 +/- 1.25 k omega. The difference was statistically significant (p less than 0.001). This difference in the resistance can be used to verify placement of the tip of the needle in the epidural space and help anesthesiologists administer epidural anesthesia.

Anesthesia, Epidural↗
PubMed1987

Renal functions following hyperbaric oxygen toxicity in conscious rats.

The after-effects of renal function were studied in rats exposed to hyperbaric oxygen (HBO) at either 4.8 ATA for 60 min or 6.8 ATA until the onset of convulsions. Only the rats which suffered from HBO convulsions were found to have alterations in renal function. It was observed that 4 hr after convulsions, there was a decrease in urinary excretion of urea and creatinine, which resulted in an elevation of blood urea nitrogen (BUN) and creatinine. Clearances of inulin and p-aminohippuric acid showed a decrease in the glomerular filtration rate and effective renal blood flow 4 hr after HBO convulsions. These parameters nearly returned to normal in 24 hr after convulsions. The renal handling of a large volume of infused saline was also retarded 4 hr after HBO convulsions, but by the end of 24 hr after HBO convulsions, it was much improved. Therefore, it was concluded that the renal function was altered after HBO convulsions, but nearly recovered in 24 hr.

Animals↗
PubMed1987

Regional differences of effects of ethanol on canine blood vessels.

In vitro effects of ethanol (0.1-2.0%,v/v) on canine vasculer smooth muscle were studied. Ethanol dose-dependently produced inhibition in both the amplitude and frequency of the spontaneous rhythmic activity of the canine hepatic portal vein, and at concentration of 1.0 +/- 0.2% completely abolished the spontaneous activity. Ethanol evoked dose-dependent constriction, rather than dilatation, in all vascular smooth muscles tested, including femoral, renal, common carotid, and pulmonary arteries, and external jugular, splenic, pulmonary, femoral, renal, and hepatic portal veins. The vasoconstriction effect of ethanol was much stronger on arteries than on the corresponding veins. Based on the contractile tension developed by ethanol, the femoral artery or the external jugular vein appeared to be most sensitive to ethanol among the arteries or veins preparations tested. The present results suggested that ethanol, depending on concentration, may either enhance or decrease excitability of vascular smooth muscles. There were also regional differences of effects of ethanol on canine blood vessels.

Animals↗
PubMed1986

Turnover of central biogenic amines in two-kidney, one-clip renal hypertensive rats.

Turnover rates, as estimated from the accumulation of the intermediates dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) following decarboxylase inhibition, were used to investigate the relationship between central catecholaminergic and serotonergic neurons and the development of hypertension in 2-kidney, 1-clip renal hypertensive rats. Results indicated that at one week following clipping, DOPA accumulation was increased in the midbrain-pons. At 5 weeks no changes were observed. At 20 weeks a lower accumulation of both DOPA and 5-HTP was observed in the posterior hypothalamus while in the medulla oblongata DOPA accumulation was lower and in the midbrain-pons 5-HTP accumulation was reduced.

5-Hydroxytryptophan↗
PubMed1986

The amino acid sequence of kinetensin, a novel peptide isolated from pepsin-treated human plasma: homology with human serum albumin, neurotensin and angiotensin.

A novel nonapeptide with neurotensin-like immunoreactivity was isolated from pepsin-treated human plasma by dialysis, ion-exchange chromatography and high performance reversed-phase liquid chromatography. The amino acid sequence was determined by automated gas-phase sequence analysis as Ile-Ala-Arg-Arg-His-Pro-Tyr-Phe-Leu. Sequence homology with human serum albumin and with the biologically active peptides neurotensin and angiotensin is demonstrated. The name proposed for this peptide is kinetensin.

Amino Acid Sequence↗
PubMed1986

Inhibitory effect in vitro of PR toxin, a mycotoxin from Penicillium roqueforti, on the mitochondrial HCO-3-ATPase of the rat brain, heart and kidney.

The effects of PR toxin, a mycotoxin from Penicillium roqueforti, on the mitochondrial HCO3- -ATPase activity of the brain, heart and kidney from male Sprague-Dawley rats were determined by measuring colorimetrically the inorganic phosphate liberated by the ATPase in the presence or absence of bicarbonate ion. The IC50 (the concentration at which 50% of the enzyme activity is inhibited) of PR toxin on the mitochondrial HCO3- -ATPase from brain, heart and kidney were 12.7, 9.2 and 14.8 microM, respectively. The Michaelis-Menten constants (Km) of the enzyme from brain (1.1 mM), heart (1.5 mM) and kidney (2.3 mM) were not changed by PR toxin. Neither neutral nor anionic detergent increased the inhibitory potency of the toxin. It was concluded that of the three tissues tested, HCO3- -ATPase of the heart mitochondria was most sensitive to PR toxin, and that the toxin inhibited the HCO3- -ATPase in a non-competitive and irreversible manner.

Adenosine Triphosphatases↗
PubMed1986

Effect of ethanol on human umbilical artery and vein in vitro.

In vitro effects of ethanol on human umbilical artery and vein were studied. Ethanol (0.5-2.0%) elicited a dose-dependent contractile response both in the umbilical arterial and venous strips in Krebs' and Ca2+-free Krebs' solution. In umbilical artery, but not in vein, ethanol shifted the CaCl2-induced dose-response curves to the right in a parallel manner along with a significant reduction in K+-depolarized maximal tension. These result demonstrate that ethanol can elicit a potent contractile response both in human umbilical arteries and veins and could aid in explaining why ethanol can induce the fetal alcohol syndrome.

Adult↗
PubMed1986

Retinoic acid enhances cell responses to epidermal growth factor in mouse mammary gland in culture.

Addition of epidermal growth factor (EGF) at up to 100 ng/ml to the medium of cultured explants of mouse mammary gland increased thymidine incorporation into DNA dose dependently. Addition of retinoic acid alone at 10 micrograms/ml to the medium had no significant effect on DNA synthesis, but addition of EGF with retinoic acid enhanced the EGF-stimulated DNA synthesis. Furthermore, pretreatment of mammary explants with retinoic acid enhanced the effect of EGF plus retinoic acid on cell growth. EGF inhibited the synthesis of casein and decreased alpha-lactalbumin activity of mammary explants in culture in the presence of insulin, cortisol, and PRL. Retinoic acid alone had no significant effect on the synthesis of casein, but suppressed alpha-lactalbumin activity dose dependently. Concomitant addition of retinoic acid with EGF had no significant effect on EGF-induced inhibition of casein synthesis, but enhanced EGF-induced inhibition of alpha-lactalbumin activity dose dependently. Measurement of specific binding of [125I]EGF to mouse mammary glands in culture demonstrated that pretreatment of the explants with retinoic acid slightly, but significantly, enhanced the specific binding of EGF to its cellular receptors.

Animals↗
PubMed1986

A new antitumor antibiotic, chounghwamycin A. I. Taxonomy, isolation and characterization.

Chounghwamycin A, a new antitumor antibiotic produced by a strain of Streptomyces sp. No. PL-D-5, was isolated and characterized. It appeared to belong to the actinomycin group of antibiotics from physico-chemical studies and has an empirical formula of C63H88N11O21. The antibiotic is extractable into an organic solvent from the fermentation broth, possessing potent antileukemic activity against P388 mouse leukemia in mice and antimicrobial activity against Gram-positive bacteria with MIC values about 0.1-0.4 microgram/ml, but showed no activity on Gram-negative bacteria, yeast and fungi tested.

Animals↗