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Biomedical subjects

D K Lee

Publications and source records attributed to D K Lee.

At least 163 records · Page 9Linked to original sources
PubMed1987

In vitro isolated tissue studies with atiprosin (AY-28,228): a new antihypertensive compound.

Using in vitro isolated tissue and binding studies we have defined a receptor activity profile for atiprosin. The most prominent action of the compound was significant alpha-adrenoceptor antagonist activity (pA2 = 8.11) that was less potent than prazosin (pA2 = 8.78) but more potent than either ketanserin (pA2 = 7.34) or indoramin (pA2 = 7.85). In addition, atiprosin was selective for alpha 1-adrenoceptors, since the compound was over 100-fold less potent as an antagonist at alpha 2-adrenoceptors (pA2 = 6.04). Atiprosin also displayed selective serotonin 5-HT2-receptor antagonist activity similar to that seen with ketanserin, but with a lesser potency (pA2 atiprosin, 6.87; ketanserin, 8.61). Although atiprosin also displayed significant histamine H1-antagonist activity (pA2 = 7.32), it was less potent as an H1-antagonist than as an alpha 1-adrenoceptor antagonist. In contrast, both indoramin and ketanserin displayed H1-antagonist activity (pA2 8.77 and 8.83, respectively) greater than their respective alpha 1-adrenoceptor antagonist activities. Atiprosin had little or no activity at either beta 1- or beta 2-adrenoceptors, muscarinic or histamine H2-receptors, nor any marked ability to produce smooth muscle relaxation either by a direct effect or via calcium entry blockade.

Adrenergic alpha-Antagonists↗
PubMed1987

Tissue-dependent alpha adrenoceptor activity of buspirone and related compounds.

The present organ chamber and receptor binding studies were designed to evaluate the alpha adrenoceptor subtype (alpha-1 vs. alpha-2) and tissue selectivity of buspirone and the related compounds, gepirone, isapirone and 1-(2-pyrimidinyl)-piperazine (a metabolite of buspirone). Buspirone, gepirone and isapirone were found to possess weak alpha-1 adrenoceptor affinity (relative to prazosin) but significant and selective alpha-1 adrenoceptor intrinsic efficacy (relative to norepinephrine, phenylephrine and ST-587), which was expressed in a tissue- and species-dependent manner. The rank order for alpha-1 adrenoceptor affinity (isapirone greater than buspirone approximately equal to gepirone) was different from the rank order for alpha-1 adrenoceptor intrinsic efficacy (buspirone greater than gepirone greater than isapirone). The tissues that were the most responsive to norepinephrine and ST-587 (i.e., rat and rabbit aorta) were the same tissues in which the intrinsic efficacy of buspirone was expressed. In contrast, 1-(2-pyrimidinyl)-piperazine was inactive at alpha-1 adrenoceptors. Although no alpha-2 adrenoceptor intrinsic efficacy was observed for any of the compounds, isapirone and 1-(2-pyrimidinyl)-piperazine displayed weak alpha-2 adrenoceptor affinity (relative to rauwolscine). Recent studies have shown buspirone to have an effect on central and peripheral monoaminergic mechanisms. The demonstration in the present study that buspirone and related compounds display significant alpha adrenoceptor activity suggests that alpha adrenoceptor involvement should be considered as a potential contributing factor in the central nervous system and/or peripheral activity of this class of compounds.

Animals↗
PubMed1987

Enzyme-linked immunosorbent assay (ELISA) of antibodies to purified protein derivative (PPD) in the diagnosis of active tuberculosis: evaluation of its potential and limitation in a high prevalence area.

Sera from patients with active tuberculosis were assayed for IgG antibodies to purified protein derivative (PPD) by an enzyme-linked immunosorbent assay (ELISA) technique. Eighty seven of the 112 patients (78%) with sputum culture-positive, and 57 of 78 patients (73%) with sputum culture-negative, pulmonary tuberculosis had positive serology. Seventeen of 19 patients (89%) with renal tuberculosis (demonstrable lesion on intravenous pyelography) had antibody to PPD, whereas only 3 of 9 patients (33%) with urinary tuberculosis (positive urine culture only, without abnormality on intravenous pyelography) and 8 of 21 patients (38%) with tuberculous cervical lymphadenitis had positive serology. Seropositivity rate in paediatric patients was also low, only 2 out of 8 patients gave positive serology. Thus, the diagnostic value of this test is limited as a positive result is obtained only when the disease is relatively long-standing or extensive.

Adult↗
PubMed1986

Clostridium difficile toxin in chronic idiopathic colitis.

Clostridium difficile toxin was isolated from the stools of three patients with chronic idiopathic colitis. Two patients were known to have chronic idiopathic colitis before Cl difficile toxin was isolated. The third patient was subsequently found to have ulcerative colitis after presentation with Cl difficile toxin in the stool. Two patients were on sulphasalazine at the time of diagnosis of Cl difficile infection and one had taken sulphasalazine two months previously. Only one patients had antibiotic exposure and that was at least three months before presentation. In each patient, treatment with vancomycin was accompanied by symptomatic improvement and disappearance of the toxin. The underlying colitis remained unaffected. In patients with inflammatory bowel disease in relapse, the presence of Cl difficile toxin should be sought as this may be a factor in the relapse. In any patient presenting with diarrhoea, the presence of Cl difficile toxin may obscure the presence of underlying inflammatory bowel disease.

Adult↗
PubMed1986

In vitro characterization of the adrenoceptor activity of AY-28,925.

The adrenoceptor activity of AY-28,925 (5-[1-hydroxy-2-[(1-methyl-3-phenylpropyl)amino]ethyl]-1 H-indole-7-carboxamide) was evaluated on various isolated vascular and nonvascular tissues. Based upon pA2 values derived from either the antagonism of the effect of isoproterenol on paced guinea pig left atria (pA2 = 7.3), spontaneously beating guinea pig right atria (pA2 = 7.4) or canine saphenous vein (pA2 = 7.3), AY-28,925 demonstrated nonselective beta adrenoceptor antagonist activity. Studies using the spontaneously beating guinea pig right atria and the prostaglandin F2 alpha-contracted canine saphenous vein indicated that AY-28,925 also possessed nonselective beta-adrenoceptor intrinsic efficacy. AY-28,925 was shown to be a selective alpha-1 adrenoceptor antagonist with a pA2 value which was greater against phenylephrine in the rabbit aorta (pA2 = 6.6) than against clonidine in the rat vas deferens (pA2 = 5.4) or B-HT 920 in the canine saphenous vein (pA2 = 5.3). Only in concentrations greater than 2000 times those required for adrenergic activity was AY-28,925 able to inhibit potassium chloride- or prostaglandin F2 alpha-induced contractions of the rabbit aorta. The compound had no significant negative intropic activity. These experiments indicate that AY-28,925 possesses, in decreasing orders of activity: nonselective beta-adrenoceptor properties; a selective alpha-1 adrenoceptor inhibitory effect; and a nonspecific direct relaxing action on vascular smooth muscle.

Adrenergic beta-Antagonists↗
PubMed1986

A subchronic study of the effect of etodolac on the gastric mucosal prostaglandin levels in the rat.

The effect of 7 consecutive days dosing with anti-inflammatory drugs on rat gastric mucosal PGE2 and 6-keto-PGF1 alpha concentrations were studied. Normal adult rats were given daily, single oral doses of etodolac (3 or 8 mg/kg/day), naproxen (3 mg/kg/day), or aspirin (300 mg/kg/day). Two hours after administration of the last dose, the animals were killed and the gastric mucosal PGE2 and 6-keto-PGF1 alpha were extracted and measured by radioimmunoassay. At equieffective anti-inflammatory doses in the rat, etodolac (3 mg/kg/day) did not significantly lower the concentrations of either PGE2 or 6-keto-PGF1 alpha, whereas both 3 mg/kg/day of naproxen and 300 mg/kg/day of aspirin significantly lowered the concentrations of both prostaglandins. The effects of naproxen and aspirin on the 6-keto-PGF1 alpha concentrations were also significantly different from that of etodolac at 3 mg/kg/day. At a higher dose of 8 mg/kg/day, etodolac did significantly lower the concentrations of PGE2 (by 33%) but not of 6-keto-PGF1 alpha. Our present data thus supports the hypothesis that the relatively weak inhibiting effect of etodolac on the gastric mucosal prostaglandin concentrations may contribute to its excellent GI profile observed in man.

6-Ketoprostaglandin F1 alpha↗
PubMed1979

Cigarette smoke inhalation decreases alpha 1-antitrypsin activity in rat lung.

Brief inhalation exposure of rats to three or six puffs of cigarette smoke significantly decreases elastase inhibitory capacity per milligram of alpha 1-antitrypsin in lung lavage fluid. This effect is not observed in ozone-tolerant rats and can be reversed by treating the lung lavage fluid from smoke-exposed rats with reducing agents. Samples of human serum obtained immediately after smoking also show decreased elastase inhibitory capacity per milligram of alpha 1-antitrypsin. Again, elastase inhibitory capacity can be restored by treatment with a reducing agent. Cigarette smoking may cause emphysema by inactivating alpha 1-antitrypsin through oxidation.

Animals↗
PubMed1976

Cytoplasmic glucocorticoid receptors in the developing small intestine of the rabbit fetus.

Glucocorticoid binding and alkaline phosphatase activity in the small intestine of the fetal rabbit were studied to investigate the relationship of glucocorticoid receptors and the development of the tissue. In the cytosol fraction, the binding of (3H)dexamethasone involves a macromolecule with high affinity (Kd = nM) for the hormone and a limited number of binding sites (saturable at a hormone concentration of 10 nM). That the binding reaction involves a protein and sulfhydryl groups was demonstrated by the absence of binding of the steroid in the presence of Pronase and sulfhydryl blocking reagents. In sucrose density gradients, the complexes have sedimentation coefficients of about 4S and 7S at low ionic strength, but only 4S at high ionic strength (0.4m KCl). The binding protein is thermolabile, and is stabilized by complexing with the hormone. The ability of different steroids to compete with (3H)dexamethasone for the binding sites correlates well with their glucocorticoid potency. During development of the fetal rabbit small intestine, the total number of glucocorticoid-binding sites in the cytosol increases in parallel with the increases in the tissue weight until term. However, the concentration of the binding sites (pmol/mg cytosol protein) is maximum at day 25 of gestation, followed by a decrease to the adult level within a few days after birth. Alkaline phosphatase activity is first detectable on day 25 of gestation and increases rapidly thereafter. These observations suggest that there may be a temporal relatioship between the development of the fetal rabbit small intestine, as reflected in the alkaline phosphatase and the levels of glucocorticoid receptors in the cytosol.

Alkaline Phosphatase↗
PubMed1975

In vivo metabolism of 3H-testosterone in adult male rats: effects of estrogen administration.

The metabolism of testosterone (T) was studied in normal adult male rats using a constant infusion of trace amounts of the 3H-steroid into a tail vein for 3 h in order to attain a state of equilibrium. Samples of plasma, liver, kidney, prostate, seminal vesicles and muscle were analysed for 3H-testosterone, 3H-5alpha-dihydrotestosterone (5alphaDHT) and 3H-5alpha-androstanediol (Adiol). When compared to the 3H-T level in plasma there were high levels of 3H-T in kidney and of 3H-5alphaDHT in prostate and seminal vesicles. Intraperitoneal estradiol valerate administration (100 mug/day) for 4 days decreased and 3H-5alphaDHT levels in the prostate and seminal vesicles. The estrogen administration increased the T metabolic clearance rate from 17.5 1/24 h/100 g body wt to 22.6 1/24 h/100 g body wt.

Androstane-3,17-diol↗