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Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 1,315 records · Page 73Linked to original sources
PubMed1994

Influence of gender on renal thiazide diuretic receptor density and response.

The influence of gender and gonadectomy on (1) the density of the renal thiazide-sensitive ion transporter, as quantitated by the ability of renal membranes to bind (3H)metolazone, and (2) the changes in the urinary excretion of electrolytes caused by maximal bendroflumethiazide (BFTZ) in Sprague-Dawley rats was determined. The density of the thiazide receptor was twofold higher (P < 0.001) in females than in males. Orchiectomy increased thiazide receptor significantly in one of two studies (P < 0.01). Ovariectomy decreased thiazide receptor by more than 20% (P < 0.01) in both studies. The rates of the urinary excretion of sodium and chloride after BFTZ and the increases in the urinary excretion of sodium, chloride, and ammonium caused by BFTZ were greater in intact females than in intact males; BFTZ decreased the urinary excretion of calcium 50% in intact females, but not in intact males. Regression analysis of the thiazide receptor (in intact and gonadectomized animals) versus the urinary excretion of electrolytes before and after BFTZ yielded a model in which one-third of the variation in thiazide receptor could be related to the change in the excretion of calcium and ammonium produced by BFTZ, raising the possibility that the density of the thiazide receptor might be related to calcium or acid-base homeostasis. It was concluded that the renal excretion of sodium, chloride, calcium, and ammonium are, in part, controlled by gender and sex hormones via their regulation of the renal density of the thiazide diuretic receptor.

Animals↗
PubMed1994

Adrenocortical steroids increase renal thiazide diuretic receptor density and response.

The density of the rat renal pharmacologic receptor for thiazide-type diuretics, as quantitated by the maximal specific binding of (3H)metolazone, decreased to one-third normal after adrenalectomy. Selective glucocorticoid (dexamethasone or RU-28362) replacement increased thiazide receptor density to or above the normal level over the dose range of steroid that decreased thymus weight, which served as a bioassay for glucocorticoid activity. Mineralocorticoid (fludrocortisone or aldosterone), in doses that did not decrease thymus weight, also increased thiazide diuretic receptor density to or above normal. The addition of glucocorticoid (RU-28362) to maximal aldosterone increased thiazide receptor above that produced by aldosterone alone and to threefold normal. Similarly, the addition of aldosterone to high-dose RU-28362 also increased thiazide receptor density above that produced by the glucocorticoid alone and to threefold normal. Hence, the effects of glucocorticoids and mineralocorticoids appeared to be additive. The increase in renal thiazide receptor density produced by fludrocortisone, at a dose that elicited both mineralocorticoid and glucocorticoid effects, was unrelated to the basal (prethiazide) renal excretion of sodium, potassium, chloride, or calcium. However, fludrocortisone-pretreated animals responded to bendroflumethiazide with a greater natriuresis than did controls. In addition, the magnitudes of the thiazide-elicited natriuresis and chloriuresis correlated significantly with thiazide receptor. It was concluded that both the density of the renal thiazide receptor and the quantity of sodium and chloride reabsorbed by the thiazide-sensitive Na-Cl cotransporter in the kidney are under adrenocortical regulation.

Adrenalectomy↗
PubMed1994

A discussion of the comprehensive index of women's status.

"As a complex system with multiple indexes, women's status must be evaluated by the use of comprehensive indexes and systematic analysis.... An evaluation of Chinese women's status in 1990 was carried out using the comprehensive index established in this article and data from the 1990 census and the Survey of Chinese Women's Social Status...."

Asia↗
PubMed1994

AML-1 gene rearrangement and AML-1-ETO gene expression as molecular markers of acute myeloblastic leukemia with t(8;21).

Rearrangements of the AML-1 gene on chromosome 21 as well as transcriptional expression of AML-1-ETO fusion gene were studied in 35 leukemic patients with t(8;21)(q22;q22). A panel of probes generated from the AML-1 gene regions flanking the breakpoint on chromosome 21 allowed us to detect the rearrangement in 24 out of 29 patients. A specific nested reverse transcriptase/polymerase chain reaction (RT/PCR) was developed to detect the t(8;21), either at diagnosis or as minimal residual disease. PCR amplification products were obtained in ten out of 11 patients investigated, and the sensitivity of the reaction was estimated to be between 1 x 10(4) and 1 x 10(-5) cell. An AML-1 rearrangement was also detected in one patient with 8q- and only one chromosome 21, but without 21q+. This indicated that the molecular rearrangement of the der(8) chromosome is more important than the reciprocal one in the malignant process.

Adolescent↗
PubMed1994

[Superinfection of hepatitis viruses].

Using ELISA method, anti-HAV-IgM and anti-HCV were determined in 493 blood donors and 192 patients with HBV infection. The positive rate of anti-HCV in blood donors was 1.62%. The superinfection rates of HBV and HAV, HBV and HCV, HBV, HAV and HCV in patients with HBV infection were 16.7%, 3.13% and 0.52%, respectively. The incidence of hepatitis B viral replication marker was found to be lower in patients with superinfection of types A and B and/or C hepatitis viruses than in those with HBV infection alone. The prolonged course was found to be longer and the degree severer in patients with superinfection of types A and B and/or C hepatitis viruses than in those with HAV or HBV or HCV infection alone. The results suggest that those patients with superinfection of types A and B and/or C hepatitis viruses showed poor prognosis and prolonged course, and many patients with chronic Type A hepatitis resulted from superinfection HBV and/or HCV.

Adolescent↗
PubMed1994

Papillomaviruses as targets for cancer gene therapy.

Gene therapy of human cancer is likely to be most effective when it is directed at targets that are expressed in cancer cells but are lacking from other cells. Human papillomaviruses can provide such targets, since these viruses are present in many cervical and oral cancers, and are likely to be etiological agents of the tumor. Continued expression of human papillomavirus genes is probably necessary for the growth of these cancers, and effective gene therapy could consist of antisense or ribozyme molecules directed against these genes. Some human papillomavirus gene products are antigenic, and immunotherapy based upon these antigens might prove clinically beneficial. Human papillomaviruses have specific promoters, are linked to toxin genes, the toxin may be selectively expressed by tumor cells where the virus genes are active. Thus, there are several approaches for the development of specific gene therapy for human cancers that contain human papillomaviruses.

Adult↗
PubMed1994

Induction, modification, and perception of the salicylic acid signal in plant defence.

Endogenous salicylic acid (SA) levels increase and several families of pathogenesis-related genes (including PR-1 and PR-2) are induced during the resistance response of tobacco to tobacco mosaic virus (TMV) infection. We have found that at a temperature (32 degrees C) that prevents the induction of PR genes and resistance, the increases in SA levels were eliminated. However, when the resistance response was restored by shifting inoculated plants to lower temperatures, SA levels increased dramatically and preceded PR-1 gene expression and necrotic lesion formation associated with resistance. SA was also found in a conjugated form whose levels increased in parallel with the free SA levels. This SA beta-glucoside (SAG) was as active as SA in inducing PR-1 gene expression. PR-1 gene induction by SAG was preceded by a transient release of SA. The existence of a mechanism that releases SA from SAG suggests a possible role for SAG in the maintenance of systemic acquired resistance. Previously, we identified a soluble salicylic acid-binding protein (SABP) in tobacco whose properties suggest that it may play a role in transmitting the SA signal during plant defence responses. This SABP has been purified 250-fold by sequential chromatography on DEAE-Sephacel, Sephacryl S-300, Blue Dextran-Agarose and Superose 6. Several monoclonal antibodies (mAbs) raised against the highly purified SABP immunoprecipitated the SA-binding activity and a 280 kDa protein. This 280 kDa protein also co-purified with the SA-binding activity during the various chromatography steps, suggesting that it was responsible for binding SA. Immunoblot analysis with the SABP-specific mAbs also detected the 280 kDa protein in highly purified preparations of SABP. However, in crude homogenates these mAbs only recognized a 57 kDa protein. These and other results suggest that SABP is a multimeric complex which contains, at least, a 57 kDa protein and whose components are readily cross-linked during purification.

Carrier Proteins↗
PubMed1994

Retinoic acid and acute promyelocytic leukemia: a model of targetting treatment for human cancer.

Acute promyelocytic leukemia (APL) is the first example among the human malignancies that responds to differentiation therapy, in that complete remission (CR) can be achieved in up to 90% of patients by using a differentiation inducer, all-trans retinoic acid (ATRA). The specific chromosomal translocation t(15;17) in APL has been shown to fuse the gene for the retinoic acid receptor alpha (RAR alpha) with a chromosome 15q locus, PML. Alterations to the RAR alpha and the PML gene structures in the t(15;17) have been characterized and used as specific molecular marker for diagnosis of the disease. PML/RAR alpha antagonizes wild-type PML and RXR and could block the differentiation pathways mediated by these two regulators. A variant translocation t(11;17) has also been discovered in a subset of APL which fuses RAR alpha to a new gene, PLZF on chromosome 11q23. Both PML/RAR alpha and PLZF/RAR alpha display the "dominant negative" effect on the wild-type RAR/RXR. However, t(11;17) APL patients differ from t(15;17) APL in that they respond poorly to ATRA. Morphologically defined APL cases which however do not have PML/RAR alpha generally show no response to ATRA. Recently it has been shown that PML/RAR alpha can be modulated directly by ATRA. All these data support the idea that PML/RAR alpha is a specific target of ATRA which can overcome the differentiation block imposed by PML/RAR alpha. The ATRA treatment of APL thus further reinforces the concept of differentiation therapy.

Gene Targeting↗
PubMed1994

[Epidemiology and control of hookworm infection in Fujian province].

Fujian province has been known to be endemic for mixed hookworm infection with Ancylostoma duodenale as the predominant species. The infection rate was 50% before 1980. As a result of mass treatment starting from 1980, the infection rate was decreased in most areas. And, infection foci were changed from sweet potato fields to the banana, sweatcane and asparagus fields where the infection rate tended to increase. It is stressed that the current endemic characteristics of hookworm infection should be paid more attention in implementing the control programme of hookworm infection.

Adolescent↗
PubMed1994

[Influence of cooling motor cortex on the inhibitory effect of stimulation of SII on nociceptive responses in ILN neurons].

Fibers from the cortical somatosensory area II (SII) or motor cortex (MCtx) to intralaminar nuclei (ILN) have been proven to exist, and SII was found to be connected with MCtx by cortico-cortical fibers. The present work was undertaken to study whether MCtx participated in SII producing descending modulation of ILN. All experiments were performed on sodium pentobarbitone anaesthetised cats. Single unit activities of ILN neurons were extracellularly recorded by glass microelectrodes. The effects of stimulating SII on nociceptive responses of ILN neurons were observed before and after cooling MCtx. The nociceptive responses of ILN neurons were attenuated by stimulating SII. There was a statistically significant difference at 0'-2' after the stimulation (n = 14, P < 0.05). The inhibitory effect of stimulating SII was reduced after cooling MCtx (19 degrees C-20 degrees C) in 8 neurons, and abolished in other neurons when the temperature was below 18 degrees C. MCtx was involved in SII producing descending modulation of ILN.

Animals↗
PubMed1994

[Experimental study of mechanism of survival of venous flaps].

The mechanism of survival of venous flaps was studied by observations employed in the study of microcirculation and blood vessel perfusion in rabbits. Initially, the flap was nourished by venous blood (within 72 hours): venous blood flowed slowly from the principal vein to its tributary veins, and then through the venous anastomoses (including small venous anastomoses, venular anastomoses and terminal venule anastomoses), reaching other tributary veins. No backflow from venules into capillaries was seen. The second stage was arterial nourishing and vessel reconstructive period (72 hours to 6 weeks): new vessels began to grow into the flaps at 72 hours postoperatively. 4 days postoperation, arterial flow with low velocity appeared in the primary flap arteries and the backflow of venous blood disappeared. 7 days postoperation, the abnormal, flow in 'unphysiologic' channels was replaced by the normal flow in 'physiologic' channels completely. 6 weeks postoperation, the vessel structure of venous flaps was the same as that of normal skin. These results suggested that rich venous network in venous flaps and early invasion of new blood vessels are the mainstay of venous flaps survival.

Animals↗
PubMed1994

[Experimental study of carbohydrate metabolism of venous flaps].

In this experimental study, three sorts of grafts (venous flap, composite graft and axial flap) were created. According to the results of relative contents of LD1, and LD5 in these grafts, the conclusion was drawn: Oxyhemoglobin remaining in the grafts maintained normal carbohydrate metabolism within 24 hours postoperatively. 48 hours later, aerobic oxidation of carbohydrate abated but kept in a considerable level in venous flaps due to the existence of venous blood. 72 hours after the operation, aerobic oxidation of carbohydrate in venous flaps reached its lowest point. At this point, the venous flaps would necrose gradually unless a new nourishing source be obtained. From the 4th postoperative day, aerobic oxidation of carbohydrate of venous flaps began to increase. By the 7th day, aerobic oxidation of carbohydrate of venous flabs returned to normal.

Animals↗
PubMed1994

[Involvement of glutamate in corticofugal modulation of intralaminar nuclei from SII via motor cortex in acupuncture analgesia].

The present experiments were designed to study the effect of glutamate on cortical somatosensory area II (S II) producing descending modulation of intralaminar nuclei (ILN) via the motor cortex (MCtx) in acupuncture analgesia. The glutamate antagonist glutamate diethylester (GDEE) or saline was topically applied at MCtx in 17 cats. Single unit activities of ILN neurons were extracellularly recorded. The results were as follows: 1. The nociceptive responses of ILN neurons were attenuated by stimulating S II after topical administration of saline at MCtx. However, the inhibitory effect of stimulating S II in the same neurons was reduced after application of GDEE. There was a significant difference at 0'-1' after the stimulation between the two groups (n = 10, P < 0.05). 2. The inhibitory effect of electroacupuncture (EA) on nociceptive responses was reduced after topical application of GDEE, while marked inhibition was shown at 0'-10' after cessation of EA in the saline control group (n = 11, P < 0.05). The results, together with the finding that the majority of S II neurons could be activated by EA, showed that glutamate released from S II to MCtx might be involved in corticofugal modulation of ILN from S II via MCtx in acupuncture analgesia.

Acupuncture Analgesia↗
PubMed1994

[Iontophoretic atropine attenuates the inhibitory effect of stimulating SmI on nociceptive responses of pf neurons].

Using the techniques of multimicropipette and iontophoresis, we observed whether ACh was involved in the cortical descending modulation of Pf neurons in rats. It was shown that the inhibition elicited by stimulation of the sensorimotor area (SmI) was attenuated after microiontophoretic atropine and that the nociceptive responses of Pf neurons were obviously reduced by microiontophoretic ACh. Therefore, it suggests that ACh may be considered as one of the neurotransmitters involved in the descending modulation of pain.

Acetylcholine↗
PubMed1994

[A study on body fat in children aged 7-12].

Three and sixty healthy children aged 7-12 with normal development and better-nourishment were selected by stratification according to their height and weight. Body density was measured with hydrostatic weighing technique. Body fat proportion was calculated with Brozek formula. Skinfolds of the four parts of the body (triceps, subscapular, etc.) were measured by Harpenden skinfolds caliper. Results showed body fat proportion in children aged 7-12 averaged 15.12% for male and 17.15% for female, with no significant difference. Body fat proportion was analyzed by stepwise regression on height, weight, skinfolds, and upper arm circumstance. Body fat proportion highly correlated to skinfolds with an r = 0.6664 and P < 0.01. A regression equation of body fat on skinfolds was developed, and laws for the development and changes of body fat discussed in the paper.

Adipose Tissue↗
PubMed1994

[A simplified method for preparation of DOCA-salt hypertension model in rats by subcutaneous implantation of DOCA silastic tube].

To study a simplified method for preparation of DOCA-Salt hypertension model in rat. 45 male SD rats (140 +/- 9 g) were used in this study. A silastic tube (length 25 mm; external diameter 4 mm; internal diameter 2.5 mm; 10-14 about 300 microns micropores on the wall) filled 100 mg DOCA in was implanted subcutaneously at the belly of the rat and followed by uninephrectomy. After operation the rat only received 1% salt solution in stead of drinking water. Hypertension developed within 3 weeks. At the 8th week after operation, systolic blood pressure (SBP) of rats was elevated to 23.3 +/- 0.37 kPa. If DOCA (10 mg/rat, weekly) was given subcutaneously, however, from control level of 16 +/- 0.16 kPa hypertension did not occur until the 5th week after injection. At the 13th week, SBP was elevated to 23.3 +/- 0.66 kPa. Difference of regression coefficients (1.295, 0.692) of SBP curves between two experimental groups was very significant (P < 0.001). Compared with subcutaneous injection, there are two advantages for method of subcutaneous implantation: (1) The rate of SBP elevation is faster and amplitude higher. (2) This method is simple and well reproducible.

Animals↗