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Biomedical subjects

H Luo

Publications and source records attributed to H Luo.

At least 289 records · Page 16Linked to original sources
PubMed1991

[Central cardiovascular and renal effects of atrial natriuretic peptide].

In 54 anesthetized rats, the changes in arterial blood pressure, heart rate and/or urine volume, urinary sodium excretion were observed following intracarotid, intrathecal and intracerebroventricular (ICV) injection of atrial natriuretic peptide (ANP). The effects of ANP on the central actions of angiotensin II (AG II) were also examined. The results were as follows: (1) In the cross-circulation preparation of rat head, MAP of the recipient was unchanged and that of the donor was decreased in response to the administration of alpha-hANP (15 micrograms/kg) into the carotid artery of the recipient. (2) By injecting AP III (5 micrograms/kg) intrathecally, MAP, HR and urine volume (V) of the rats (n = 7) showed no change. (3) The ICV injection of AP III (20 micrograms/kg) did not result in changes in MAP, HR, and urinary sodium excretion (UNaV), but there was a transient and significant increase in V. (4) ICV injection of AG II (1 microgram/kg) resulted in an increase of MAP by 1.3 +/- 0.17 kPa (10 +/- 1.3 mmHg, n = 10, P less than 0.001), V by 106% (n = 6, P less than 0.01) and UNaV by 642% (P less than 0.01). (5) ICV injection of AP III 2 min prior to the injection of AG II by the same route, the central hypertensive effect induced by AG II was not affected, while the increments in V and UNaV were decreased significantly (P less than 0.05). The results indicate that (1) ANP is incapable of penetrating the blood-brain barrier owing to its large molecular size and therefore, the central mechanism is not involved in the hypotensive effect induced by intravenous injection of ANF and (2) the central diuretic and natriuretic actions of AG II may be markedly inhibited by ICV injection of ANP, thus indicating the existence of some central antagonistic interactions between AG II and ANP.

Angiotensin II↗
PubMed1990

Solubilization of thiazide diuretic receptors from rat kidney membranes.

Thiazide-type diuretics act at receptors to inhibit NaCl transport in the renal distal tubule. We solubilized high-affinity [3H]metolazone binding sites from rat kidney membranes with Triton X-100, which was more effective than several other detergents. Phosphatidylcholine and a mixture of proteinase inhibitors were needed to stabilize binding so that 57% of solubilized binding remained after 72 h at 4 degrees C. The affinities of solubilized (Kd = 11.4 +/- 0.5 nM) and membrane-bound receptors (Kd = 12.0 +/- 1.7 nM) were similar. The maximal number of binding sites/mg protein of solubilized receptors was 46 +/- 3% (n = 5) of membrane-bound receptors. Diuretics with a wide range of affinities had similar affinities for the solubilized and membrane-bound sites. Chloride inhibited and sodium stimulated the binding of [3H]metolazone to solubilized receptors, as they do with membrane-bound receptors. These studies demonstrate that, as judged by ligand binding, thiazide receptors can be solubilized in an active conformation and provide the basis for future purification and reconstitution.

Animals↗
PubMed1990

[Hemodilution in the treatment of acute cerebral thrombosis].

11 cases of acute cerebral thrombosis were treated with a combination of venesection (400-800 ml of blood being let out at a time) and administration of an equal volume of low-molecular weight dextran solution Thereafter 500 ml of the dextran solution was given to each patient every day for 15 days. A comparison was made between this group and another group of patients who received just dextran. In the venesection group the mean value of hemoglobin was reduced from 15 g% to 13 g%, that of hematocrit from 44.6% to 40%, and that of the whole blood viscosity from 5.15 to 4.40. The neurological scores showed marked changes after three days of venesection. On the 21st day the scores in the venesection group increased by 31.6% (20.1 points) and that in the control group increased by 12.6% (7.7 points). Evidently the venesection group resulted in much better recovery (P less than 0.001).

Blood Viscosity↗
PubMed1990

[Experimental infection index of Anopheles sinensis and melanization of periodic Brugia malayi larvae].

This paper deals with the infection index of Anopheles sinensis infected with the blood meals of 9 different microfilarial densities (5-300 mf/10 microliters) of periodic Brugia malayi. The results indicated that the mean number of microfilariae (mf) ingested by mosquitoes increased with the mf-density of the blood meal. The infection rates of vectors were 30, 65, 93 and 100%, when mf-densities were 5, 10, 20 and 50 mf/10 microliters respectively. Although the infection rate was 100% when mf-densities were larger than 50 (100, 150, 200, 250, 300) mf/10 microliters, the infection intensities were gradually increased from 17.2 to 51.4 and the host efficiencies were decreased from 0.4135 to 0.2328. The infection intensities and host efficiencies of low mf-densities (5, 10, 20, 50 mf/10 microliters) were 1.22-8.40 and 0.5669-0.6356 respectively. Under the condition of 27.5 +/- 0.5 degrees C, RH 75 +/- 5%, the developmental period from mf to third stage larva was 8 days and numerous infective larvae could be harvested when mf-density was 200 mf/10 microliters. The relationship between mf-density and host efficiency, number of melanized larvae and susceptibility of vector, experimental infection indices of Kartman and of Wharton were discussed.

Animals↗
PubMed1990

[Preparation of inside-out vesicles from red blood cell membranes and measurement for its Ca2+ uptake].

Sealed, inside-out red cell membrane vesicles (IOV) from rats were prepared by a modified method of Steck (1974). The preparation contained 70% of IOV. In the presence of ATP and Mg2+, these vesicles actively took up Ca2+ with a high efficiency and reproducibility. The intraassay coefficient of variance (C.V.) was 3.6% and the interassay C.V. was 13.58%. The active Ca2+ transport reached the maximal level in 10 minutes of incubation, and linearly correlated with the IOV concentration. The Ca2+ uptake rate in Wistar rats was 9.39 +/- 1.28 nmol/mg IOV protein/min. IOV rapidly lost Ca2+ when A23187 was added. The active transport was stimulated by calmodulin, and inhibited by trifluoperazine.

Adenosine Triphosphate↗
PubMed1990

[Left ventricle diastolic function in hypertensive patients and responses to captopril].

The LV diastolic function of 37 cases with primary hypertension were studied by measuring the diastolic filling blood stream at mitral orifice using pulsed Doppler echocardiography. 30/37 (81%) patients were found to have impaired LV diastolic function as compared with 30 normals of a group at similar age. After 4 weeks of oral captopril treatment in 20/37 patients, BP dropped in 19/20; LV diastolic function improved in 75-80%; left ventricular mass also regressed in 16/20 captopril treated patients (210 +/- 62 vs 171 +/- 46 g, P less than 0.01). It showed that captopril is not only effective in lowering blood pressure but also in improving the impaired LV diastolic function.

Adult↗
PubMed1989

IgE synthesis by chronic lymphocytic leukemia cells.

The present results indicate that B cells isolated from chronic lymphocytic leukemia (B-CLL) from 11 of 14 patients are capable of specifically producing IgE upon costimulation with IL-4 and hydrocortisone (HC). IgE is detected by intracytoplasmic fluorescence staining and by RIA. Clinical, hematological, and immunological parameters (including Rai stage, WBC, Lc, sIg kappa/lambda, CD5, and CD23 expression) cannot distinguish the IgE responder from the nonresponder patients. IL-4 alone is a potent inducer of human IgE synthesis by normal PBMC and we show here that its effect is strikingly enhanced by HC. The IgE produced by B-CLLs are monoclonal since they display the same L chain type as the freshly isolated CD5+ B-CLLs. We, therefore, conclude that the combination of IL-4 and HC can abrogate the maturation arrest of CD5+ B-CLLs by inducing their differentiation into IgE-producing cells. The present data provide a unique model to study the isotype switching to IgE and the regulation of human IgE synthesis by monoclonal human B cells.

Antigens, Differentiation↗
PubMed1989

Effect of ligustrazine on Ca2+ uptake by inside-out red cell membrane vesicles from renal hypertensive rats.

The effect of ligustrazine (Lig) on blood pressure and Ca2+ uptake by inside-out red cell membrane vesicles (IOV) was investigated in renal hypertensive rats (RHR). After oral administration of Lig (30 mg/kg body weight/day) for 10 days, the blood pressure of RHR was not significantly changed (before vs after experiment: 147.50 +/- 2.50 vs 150.00 +/- 13.42 mmHg). The active Ca2+ uptake rate of IOVs from RHR was 5.03 +/- 1.15 nmol/ng IOV protein/min, and this was lower than that of IOVs from normotensive Wistar rats (8.95 +/- 1.08 nmol/ng IOV protein/min, P less than 0.01). In RHR, no change in IOV Ca2+ uptake capacity was observed after administration of Lig in vivo. Experiments in vitro showed that Lig markedly reduced Ca2+ uptake by IOVs from both RHR and control rats. The results indicate that the active Ca2+ transport capacity of red cell membranes is decreased in RHR and not significantly affected by oral administration of Lig; this drug, however, exerts an inhibitory effect on the transport process in vitro.

Animals↗