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Biomedical subjects

W K Ho

Publications and source records attributed to W K Ho.

At least 127 records · Page 7Linked to original sources
PubMed1982

Binding of homologous versus heterologous low density lipoproteins by different tissues of the rat.

1. The ability of five different tissues of the rat to bind homologous and heterologous (human) low density lipoprotein (LDL) was compared. 2. Human LDL was as effective as rat LDL in displacing rat [125I]LDL from the plasma membrane fraction of rat skeletal muscle. 3. Membranes from rat liver appeared to have no affinity for homologous LDL, while human LDL was slightly more effective in displacing labeled rat LDL from this tissue. 4. A similar pattern of displacement was observed in membranes derived from rat heart. 5. In contrast, membranes from both the aorta and adrenal glands of the rat displayed a significantly greater affinity for binding LDL of homologous origin. 6. These results suggest that lipoprotein receptors analogous to those described for cultured human cells may exist in the rat and that individual tissues exhibit distinctly different affinities for binding LDL of both homologous and human origin.

Adrenal Glands↗
PubMed1980

The inhibitory action of two thrombin inhibitors (TI-189 and TI-233) on the contractile responses to 5-hydroxytryptamine and prostaglandin endoperoxide analogue (U-44069) in isolated vascular strips.

1. Two arginine derivatives that were developed as thrombin inhibitors (TI-189 and TI-233) selectively inhibited the 5-hydroxytryptamine (5-HT)-induced contraction of rabbit aortic strips in a competitive manner. The PA2 values of TI-189 and TI-233 were 5.24 +/- 0.21 and 6.23 +/- 0.32 respectively. 2. Even at 10(-4) M they had no inhibitory effect on the contractile response to noradrenaline (NA), histamine, prostaglandin E2 (PGE2), PGF2 alpha, arachidonic acid or potassium in rabbit aortic strips. 3. In dog basilar and coronary arterial strips and also in rat fundus, both agents inhibited the 5-HT response in a non-competitive manner. 4. At 10(-5) M, TI-233 but not TI-189 antagonized effects of NA and KCl in the dog basilar and coronary arteries. 5. These arginine derivatives decreased the contractile responses induced by a prostaglandin endoperoxide analogue (U-44069) in rabbit aorta and in dog basilar and coronary arteries but there was no evidence for competitive antagonism. 6. These results indicate that the arginine derivatives are competitive antagonists selective for 5-HT receptors in rabbit aorta.

Animals↗
PubMed1980

Possible generation of potent vasocontracting substance from prostaglandin endoperoxide analogs, human platelets mixture.

The mixture of human platelets and prostaglandin (PG) endoperoxide analogs (U46619 and U44069) at threshold concentrations caused a marked enhanced vasocontraction of rabbit aortae and bovine coronary arteries. THe configuration of the mixture-induced contraction was a sustained and tonic form. On the other hand, the thromboxane A2-like substance which was generated during the incubation of arachidonic acid with human platelets caused a transient and phasic contraction, and the amplitude of this contraction was much less than that of the mixture. Even after exposure to high temperature for various time periods, the mixture was still able to cause the enhanced vasocontraction. However, this mixture lost the activity of vasocontraction after an incubation in strong acid (pH 1) or alkali (pH 12) for 10 min. Serotonin and alpha adrenoceptor antagonists had no effect on the mixture-induced contraction. When tissues were incubated in Ca-free medium for a few minutes, the mixture failed to cause vasocontraction, whereas the contractile responses to histamine, norepinephrine and serotonin were not affected. When tissues were pretreated with imidazole (10(-5) M), which is a thromboxane synthetase inhibitor, the vasocontration induced by the mixture was potentiated rather than inhibited, whereas the thromboxane A2-like substance-induced contraction was inhibited. When either the tissue was pretreated with or platelets were incubated with indomethacin, the mixture failed to cause the enhanced vasocontraction. The new synthetic arginine derivatives (T1189 and T1233) nearly abolished the vasocontractile response to the mixture. However, both derivatives failed to inhibit the vasocontractions of PGE2 and PGF2 alpha, arachidonic acid and KCl. These results suggest the possibility that during the incubation of endoperoxides with human platelets a potent vasocontractile substance could be generated and such a substance does not resemble thromboxane A2 or any of the PGs tested.

Adult↗
PubMed1979

Changes in adrenocorticotropic hormone (ACTH) and cortisol levels in drug addicts treated by a new and rapid detoxification procedure using acupuncture and naloxone.

Plasma ACTH, cortisol, and cyclic-AMP levels of eleven heroin addicts were dertermined before and after treatment with a fast detoxification procedure using acupuncture and electrical stimulation (AES) together with the administration of limited doses of naloxone. At the end of the treatment period, the average plasma ACTH, cortisol, and cyclic-AMP level rose 130,83, and 24 percent, respectively. In view of the appearance of mild withdrawal signs during this method of treatment, the observed increases in ACTH and cortisol levels probably reflect the inability of AES to suppress withdrawal symptoms induced by naloxone completely. The mechanism underlying this new method of treatment is discussed in relation to AES's ability to stimulate the secretion of endorphins.

Acupuncture Therapy↗
PubMed1979

The influence of electro-acupuncture on naloxone-induced morphine withdrawal. II. Elevation of immunoassayable beta-endorphin activity in the brain but not the blood.

The effect of electro-acupuncture in the treatment of naloxone precipitated morphine withdrawal in mice was studied. Thirty minutes of acupuncture was enough to suppress withdrawal behaviors by more than 60%. Concomitant to the decrease of withdrawal behavior, there was a significant increase of brain beta-endorphin level in the acupunctured animals. Plasma beta-endorphin level of the treated and untreated group was not significantly different.

Acupuncture Therapy↗
PubMed1978

Reduction of adrenocorticotropic hormone (ACTH) and cortisol in drug addicts treated by acupuncture and electrical stimulation (AES).

Forty-two heroin addicts and 31 normal persons were examined for the effect of acupuncture and electrical stimulation (AES) on plasma ACTH, cortisol and cyclic-AMP levels. Both ACTH and cortisol levels were reduced significantly in the addicts after treatment whereas no such significant reduction was observed in the normals. Plasma cyclic-AMP level was not affected in either group. Taken together, results from the present study suggest that the mechanism of AES in the treatment of addiction may have a neuroendocrinological basis. This hypothesis is particularly attractive in view of the isolation of opiate-like peptides from the brain.

Acupuncture Therapy↗
PubMed1977

Comparison of plasma hormonal levels between heroin-addicted and normal subjects.

The serum concentrations of ACTH, cortisol, aldosterone, thyroxine, cyclic AMP and cholesterol were compared between normal and heroin-addicted subjects. Significantly lower ACTH, cyclic AMP and cholesterol levels were observed to be associated with the heroin addicts, but their plasma thyroxine level was significantly elevated. The possible physiopsychological effect resulting from these changes is discussed.

Adolescent↗