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Biomedical subjects

Z Ni

Publications and source records attributed to Z Ni.

At least 73 records · Page 4Linked to original sources
PubMed1996

Elevation of cytosolic calcium of rat cardiac myocytes in phosphate depletion.

Phosphate depletion is associated with a rise in cytosolic calcium ([Ca2+]i) of cells and such a derangement is responsible in major part for organ dysfunction in phosphate depletion (PD). Cardiac function is impaired in PD, and it is possible that PD is also associated with rise in [Ca2+]i of cardiac myocytes. The present study examined the effect of PD on [Ca2+]i of cardiac myocytes and explored the mechanisms that may lead to the rise in their [Ca2+]i. The [Ca2+]i of cardiac myocytes began to rise and ATP content began to fall at the third week of PD. After six weeks of PD, the values of [Ca2+]i were significantly higher (P < 0.01) and those of ATP content were significantly lower (P < 0.01) than in control (PW) rats. The Vmax of Ca2(+)-ATPase and Na+,K(+)-ATPase as well as the Na(+)-Ca2+ exchange were significantly lower (P < 0.01) in PD than in PW animals. The data of the present study are consistent with the notion that the rise in [Ca2+]i of cardiac myocytes of PD rats is due to a decrease in calcium efflux out of them.

Adenosine Triphosphate↗
PubMed1996

Research into analgesia by inhaling analgesic.

This article deals with analgesia by inhaling analgesic. According to Chinese medical theories, TCM analgesics were chosen from the literature and folk prescriptions screened and proved by analgesic tests on animals. A reasonable prescription was made up and the drug inhaled. Its analgesic effect was superior to that of dolantin injection (3 mg/kg body weight, intraperitoneal injection). Clinical trials showed its analgesic effect in 3-10 minutes and it lasted for more than 2 hours in over 70% of the cases for a total effective rate of 94.6%. The drug is absorbed quickly and acts directly on the nerve center. Its use is not addictive.

Administration, Inhalation↗
PubMed1996

[Histopathological classification of 3,510 cases with eyelid tumor].

OBJECTIVE: To study the histopathological classification of eyelid tumor. METHOD: The pathological specimens of 3,510 cases with eyelid tumor examined between 1953-1992 were retrospectively analyzed. RESULTS The 5 leading malignant lid tumors were basal cell carcinomas (430 cases, 37.6%), meibomian gland carcinomas (363, 31.7%), squamous cell carcinomas (216 cases, 18.9%), melanomas (56 cases, 4.9%) and malignant lymphomas (21 cases, 1.8%). The 5 leading benign lid tumors including papillomas (658 cases, 27.9%), pigmented nevi (578 cases, 24.4%), cysts (427 cases, 18.1%), angiomas (222 cases, 9.4% including 10 lymphangiomas) and verrucae (212 cases, 9.0%). Rare tumors of the eyelid included one case of each of the following tumors: reticulum cell sarcoma, adenocystic carcinoma, malignant mesenchymoma, mucinous adenocarcinoma, Bowen's disease, basosquamous carcinoma, basosebacious carcinoma, teratoma, granular cell tumor (myoblastoma), angiolymphoid hyperplasia with eosinophilia, osteoma, etc. CONCLUSION: The classification and differentiation in type of eyelid tumor are beneficial to the histopathological diagnosis.

Basal Cell Carcinoma↗
PubMed1995

Elevated cytosolic calcium of adipocytes in chronic renal failure.

Chronic renal failure (CRF) is associated with increased calcium content of, and impaired lipase release from lipid cells. This has been attributed to a rise in the cytosolic calcium ([Ca2+]i) of these cells. However, data on [Ca2+]i of lipid cells in CRF and on the mechanisms responsible for such an abnormality are lacking. To study this issue we examined the [Ca2+]i and ATP content of lipid cells and Vmax of Na(+)-K(+)-ATPase and Ca2+ ATPase of membrane preparation and Na(+)-Ca2+ exchange of membrane vesicles of adipocytes from normal rats, 6 week CRF, CRF normocalcemic parathyroidectomized (CRF-PTX) and CRF, and normal rats treated with verpamil (CRF-V, normal-V). [Ca2+]i in adipocytes of CRF rats was higher (199 +/- 8.5 nM) and ATP lower (2.9 +/- 0.31 nmol/10(6) cells) than in normal (120 +/- 4.3 nM; 5.7 +/- 0.27 nmol/10(6) cells), CRF-PTX (128 +/- 4.7 nM; 5.8 +/- 0.39 nmol/10(6) cells), normal-V (121 +/- 3.2 nM; 5.3 +/- 0.36 nmol/10(6) cells), CRF-V (123 +/- 7.4 nM; 5.5 +/- 0.30 mmol/10(6) cells). Vmax Ca2+ ATPase and the activity of Na(+)-K(+)-ATPase and of Na(+)-Ca2+ exchanger were reduced in CRF rats as compared to the other four groups of rats. The values in normal, CRF-PTX, CRF-V and normal-V rats were not different.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1995

Impaired agonist-induced calcium signaling in hepatocytes from chronic renal failure rats.

Some hormones exert their action by inducing a rise in cytosolic calcium [Ca2+]i (calcium signal), and therefore, a blunting in hormone-induced calcium signal would engender resistance to the action of the hormone. Chronic renal failure (CRF) is associated with resistance to the action of a variety of hormones, a rise in [Ca2+]i and decrease in the amount of mRNA of one hormone receptor, the PTH-PTHrP receptor. We examined the calcium-signal induced by PTH, angiotensin II, vasopressin and glucagon in hepatocytes from CRF animals, evaluated the effect of the basal level [Ca2+]i on the calcium signal and explored the effect of [Ca2+]i on the mRNA of the receptors of these agonists. Hepatocytes from CRF rats have elevated basal levels of [Ca2+]i and display significantly reduced calcium signals induced by all these hormones, while the calcium signals were normal in PTX-CRF animals and those treated with verapamil both of which have normal levels of [Ca2+]i despite CRF. The calcium signals induced by dibutyryl cyclic AMP and G protein activator (GTP gamma S) were normal in hepatocytes from CRF animals despite the high levels of [Ca2+]i. Northern blotting experiments revealed that the levels of the mRNA of the receptors of PTH-PTHrP, angiotensin II and vasopressin were significantly reduced in hepatocytes from CRF animals but PTX-CRF rats and those treated with verapamil had either significantly greater or even normal amounts of the mRNA of these receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Function and metabolism of brain synaptosomes in chronic renal failure.

Patients with advanced renal failure have derangements in the function of their nervous system. The available clinical and experimental data indicate that the state of the secondary hyperparathyroidism of renal failure plays a major role in the genesis of the nervous system dysfunction. The excess parathyroid hormone (PTH) mediates its deleterious effect by causing an elevation in cytosolic calcium of brain cells. This report reviews the evidence leading to the conclusion that PTH is a major uremic toxin.

Acetylcholine↗
PubMed1995

[Establishment and characteristics of a model of nude mouse xenograft of human retinoblastoma].

The authors reported the establishment and biological characteristics of a model of nude mouse xenograft of human retinoblastoma (RB). Immediately after the enucleation of the human globe with RB, the tumor tissue was transplanted subcutaneously into a nude mouse. The tumor grew constantly and was passaged serially for 14 passages till now. The results of the following examinations of the xenograft and primary tumor were compared: light and electron microscopy, immunohistochemistry, flow cytometry and chromosome analysis. The comparisons reveal that the main biological characteristics of the xenograft model are consistent with those of the primary tumor and also maintain throughout the serial passages. The model can be used for further laboratory studies.

Animals↗
PubMed1994

Altered cytosolic calcium homeostasis in rat cardiac myocytes in CRF.

Chronic renal failure (CRF) is associated with an increase in calcium content of heart. This was attributed to the secondary hyperparathyroidism of CRF, since PTH augments entry of calcium into cardiac myocytes. At present, it is not known whether the increase in calcium content of heart reflects a rise in basal levels of cytosolic calcium ([Ca2+]) of cardiac myocytes. Further, in order for the PTH-induced entry of calcium into cardiac myocytes to raise their basal levels of [Ca2+]i, calcium extrusion out of these cells should be impaired as well. The present study examined the effect of CRF with and without excess PTH (PTX) and of the treatment of CRF rats with verapamil on basal levels of [Ca2+]i and ATP content of cardiac myocytes and on the activities of the pumps that are directly (Ca(2+)-ATPase and Na(+)-Ca2+ exchanger) and indirectly (Na(+)-K+ ATPase) responsible for calcium extrusion out of these cells. The basal levels of [Ca2+]i of cardiac myocytes increased (P < 0.01) and their ATP content decreased (P < 0.01) as the duration of CRF advanced. CRF was associated with significant decrement in Vmax of Ca2+ ATPase and Na(+)-K+ ATPase and in Na(+)-Ca2+ exchange. These derangements were prevented by prior PTX of the CRF rats or by their treatment with verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1994

Sequence of appearance of the metabolic derangements in rat brain synaptosomes during phosphate depletion.

Chronic phosphate depletion (PD) causes a rise in basal level of cytosolic calcium ([Ca2+]i) in rat brain synaptosomes, a decrease in their ATP content and a reduction in Vmax of their Ca2+ ATPase and Na(+)-K+ ATPase. The chronology of the events that lead to these derangements is not elucidated. The present study examined this issue by evaluating the changes in rat in these parameters in brain synaptosomes during the evolution of PD over a period of 6 weeks. The results show that the initial derangement is a rise in the Vmax of Ca2+ ATPase during the first 2 weeks of PD. This is followed by a rise in [Ca2+]i, a fall in ATP content and decrease in the Vmax of Ca2+ ATPase and Na(+)-K+ ATPase by the end of the 3 week and most of these derangement worsened during the 4th to 6th weeks of PD. Taken together our data are consistent with the notion that PD is associated with an initial increase in calcium influx into the synaptosomes. This is followed by a modest but significant rise in [Ca2+]i which in turn would inhibit mitochondrial oxidation and ATP generation leading to a decrease in ATP content. The latter compromises the activity of Ca2+ ATPase and Na(+)-K+ ATPase which are involved, directly or indirectly, in calcium extrusion out of the synaptosomes. The increased entry of calcium combined with decreased calcium extrusion are followed by a further rise in basal levels of [Ca2+]i.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1994

Effects of parathyroid hormone on cytosolic calcium of rat adipocytes.

Available data indicate that adipocytes are targets for PTH action, and chronic excess of PTH increases calcium burden of fat tissue, suggesting that PTH increases entry of calcium into adipocytes. The present study examined the effects of PTH-(1-84) and its amino-terminal fragment, PTH-(1-34), on cytosolic calcium ([Ca2+]i) of adipocytes and evaluated the cellular pathways that mediate the potential effect of PTH on [Ca2+]i of these cells. PTH-(1-84) but not PTH-(1-34) produced a dose-dependent rise in [Ca2+]i of adipocytes. This effect occurred in the presence or absence of calcium in the media, but the magnitude of the rise in [Ca2+]i was significantly greater when calcium was present in the media. The PTH antagonist [Nle8,18Tyr34]bPTH(7-34)NH2, verapamil, and nifedipine blocked to variable degrees the PTH-induced rise in [Ca2+]i. The phorbol ester 12-O-tetradecanoyl phorbol-13-acetate, and the GTP-binding protein (G protein) GTP gamma S also produced a dose-dependent rise in [Ca2+]i of adipocytes. These effects were inhibited by staurosporine and the G protein inhibitor guanosine 5'-O-1(2-thiodiphosphate), respectively. Similary, staurosporine, calphostin C, guanosine 5'-O-1(2-thiodiphosphate), and pertussis toxin inhibited the effect of PTH on [Ca2+]i of adipocytes. (Bu)2cAMP also increased [Ca2+]i of adipocytes, but PTH did not stimulate cAMP production by adipocytes, and N-[2(p-bromocin-namylamino)ethyl]5-isoquinoline-sulfonamide, an inhibitor of protein kinase A, did not affect the PTH-induced rise in [Ca2+]i of adipocytes. The data indicate that: 1) PTH-(1-84) increases [Ca2+]i of adipocytes; 2) this action of the hormone is receptor mediated; 3) the hormone uses a G protein activation of calcium channels and the phospholipase C pathway in mediating its action on [Ca2+]i; and 4) the rise in [Ca2+]i is due to both increased calcium influx into the adipocytes and mobilization of calcium from intracellular stores.

Adipocytes↗
PubMed1994

[Computer assisted studies on the structural requirements for the mutagenicity in Salmonella reversion assay for organophosphorus pesticides].

Computer assisted molecular fragment evaluation (CAMFE) program has been established and applied to the data set analysis of the mutagenicity of 59 organophosphorus pesticides (OPPs) in Salmonella reversion assay. The results favour the hypothesis that the mutagenic properties of OPPs lie in their alkylation to DNA mainly by the molecular fragments containing methyl groups rather than those containing ethyl groups. Oxygen atom in phosphoryl group may prompt the mutagenic ability induced by OPPs; However, the mutagenic ability may be decreased by sulfur atom, the substitute of oxygen atom at the same site in PPs structure. It was suggested that, among the most relevant fragments, the methoxyphosphinyl group appears as the common structural subunit responsible for the activities detected in the Salmonella reversion assay, while the ethyl thionophosphinyl group appears as the descriptor of negative results.

Insecticides↗
PubMed1993

Derangements in acetylcholine metabolism in brain synaptosomes in chronic renal failure.

Chronic renal failure causes abnormalities in the central nervous system function and in norepinephrine metabolism of brain synaptosomes. The present study examined the effect of renal failure on the metabolism of another neurotransmitter, acetylcholine, which is involved in the modulation of behavioral and motor function. We measured acetylcholine content and release, choline content, uptake and release and activity of choline kinase in synaptosomes from rats with renal failure with various duration, renal failure-parathyroid-ectomized rats maintained normocalcemic, renal failure and normal rats treated with verapamil. Acetylcholine content increased while choline content decreased proportionally and significantly (P < 0.01) with the duration of renal failure; choline kinase activity was reduced (P < 0.01). These derangements were prevented by parathyroidectomy of renal failure rats or by their treatment with verapamil. Choline uptake and release were elevated in renal failure and these abnormalities were not corrected by parathyroidectomy or verapamil therapy. Acetylcholine release was elevated in renal failure and parathyroidectomy prevented this derangement. Verapamil reduced acetylcholine release in both normal and renal failure rats. The data show that: (a) renal failure causes significant derangements in acetylcholine metabolism leading to its accumulation in and an increase in its release from brain synaptosomes; (b) this is mainly due to reduced activity of choline kinase, most likely, mediated by the state of secondary hyperparathyroidism of renal failure; (c) blocking the parathyroid hormone-induced calcium influx into synaptosomes by verapamil prevented the abnormalities in acetylcholine metabolism; and (d) the derangement in choline uptake and release in CRF is not related to excess parathyroid hormone since parathyroidectomy or verapamil treatment did not correct them.

Acetylcholine↗
PubMed1993

[Production of transgenic rabbits by micro injection].

The feasibility of using whole animal instead of bioreactor in genetic engineering has been investigated with transgenic domestic rabbits. The gene chosen is the surface gene (S gene) of hepatitis B virus. Two plasmids were specifically constructed for this purpose, pHBV3.0 contains the promoter pre S gene and a part of c gene of the virus; while MT-SA, the S gene and mouse MT promotor. These plasmids were made linear by suitable restriction endonuclease before they were transferred into maleprounclei by means of microinjection. From 757 microinjected and transplanted fertilized eggs 101 rabbits were obtained. 57% of these animals were found with integrated microinjected genes. 28 of the transgenic animals were tested for the presence of the surface antigen of the virus in the serum by ELISA method. 8 animals were found positive, approximately 30% of the tested transgenic animals. The second generation transgenics were obtained either by first generation ransgenics crossed with non-trans-genics or transgenics. Among them 73% contained the transgene and 15% had the surface antigen in the serum. Some experiments were also carried out with human growth hormone gene.

Animals↗
PubMed1993

[Induction of micronucleus by organophosphorus pesticides both in vivo and in vitro].

A total of 22 organophosphorus pesticides (OPPs), including 8 ethyl-, 9 methyl-, and 5 other OPPs, were tested for mutagenicity in micronucleus assay system both in 615 mouse marrow cells in vivo with multi-intraperitoneal administrations and in cultured Chinese hamster lung (CHL) cells in vitro; and structure-mutagenicity relationship of OPPs was analyzed. Among the OPPs tested in vivo, 5 ethyl-(diazinon, chlorpyrifos, disulfoton, ethion, and parathion), and only 1 methyl-(dimethoate) were found mutagenic, while the other OPPs were negative. Six ethyl- (azinphos ethyl, chlorpyrifos, ethion, parathion, phosaione, and quinaphos), 8 methyl- (azinophos methyl, chlorpyrifos methyl, dichlorvos, dimethoate, fenitrothion, malathion, parathion methyl, and trimethyl phosphate), and 2 other OPPs (EII and MIA), however, induced micronucleus in CHL cells in vitro. The results indicated that most of the ethyl-OPPs tested showed the ability to induce micronucleus both in vivo and in vitro, and that most of the methyl-OPPs were positive only in vitro. The mechanism for the adversity of mutagenic activity in micronucleus assay in vivo and in vitro produced by different kinds of OPPs was also discussed.

Animals↗
PubMed1991

Design and compliance of HBV vaccination trial on newborns to prevent hepatocellular carcinoma and 5-year results of its pilot study.

A large-scale, controlled study of universal immunization of newborns against HBV infection has been conducted in the high incidence area of hepatocellular carcinoma, Qidong County of China. This area has a stable population, standardized cancer registration system, and an epidemiological base for measurements of liver cancer prevention by vaccine. Randomization was done on the community level. The vaccination and the control group each will consist of 38,000 children by the end of 1990. It is anticipated that the design will provide high statistical power to detect 50% reduction in the prevalence rate of chronic hepatitis among the vaccinees vs. the controls at 6 to 10 years of age, and 50% reduction in the incidence rate of hepatocellular carcinoma at 35 to 40 years of age. The vaccine used is Hep-B Vax, donated by Merck and Co. through WHO. The vaccine was administered at 0, 1, and 6 months after birth, the dosage of 5 or 2.5 micrograms in the pilot study as used before 1985 and of 5 micrograms dose level during the main study starting from January 1, 1985. About 85% of the cohorts have now entered the protocol. The vaccination coverage during 1984 to 1989 was 98.0% (35,064/35,789). Follow-up of the vaccinees and the age-matched controls at 5 years has exceeded 97%. The cumulative mortality in the vaccinated group up to 1988 was 1.29% (354/27,450). No single death nor serious adverse reaction was found that was associated with vaccination. The use of HBV vaccine at a reduced dose was especially important for the developing countries at the present time in order to achieve widespread immunization. Five-year results of the pilot study of this vaccination project showed that significant protection against HBV infection was achieved with the 5 or 2.5 micrograms per dose regimen plus a booster of 5 micrograms given at 3.5 to 4 years of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Hepatocellular↗
PubMed1991

Cytosolic calcium is normally distributed in brain synaptosomes of normal and chronic renal failure rats.

Available data indicate that the basal levels of cytosolic calcium ([Ca2+]i) varies widely in polymorphonuclear leukocytes and in thymocytes. The present study examined whether a similar phenomenon exists in other cells. We measured the basal level of [Ca2+]i in brain synaptosomes of normal and chronic renal failure (CRF) rats. We find these levels (278-439 mM) vary widely in both normal rats and in CRF animals (350-495 mM) as well. However, despite these wide variations, the values followed normal distribution in both groups of animals. The data are consistent with the proposition that the values of [Ca2+]i in many cells display wide variations among a particular species and the levels are most likely predetermined genetically for each animal.

Animals↗
PubMed1990

Prevalence survey of cytomegalovirus infection in children in Chengdu.

Cytomegalovirus (CMV) is a common worldwide perinatal infection. Although usually asymptomatic, it may cause deafness in up to 15% of these infants. A cross-sectional study was performed to determine the age-specific prevalence of CMV seropositivity in Chinese children and to determine if any risk factors for infection could be identified. In a two-stage sampling procedure, nine districts were randomly selected from 70 citizenship districts in Chengdu, Sichuan Province, People's Republic of China. Then, 1,950 households were randomly selected from 11,886 households and interviewed. Blood was obtained from all children aged less than seven years and assayed using an enzyme-linked immunosorbent assay method. A subgroup of sera was retested at the research laboratory and also sent to the National Reference Laboratory in Beijing. Kappa values for the test agreement with the reference laboratory and retesting within the study laboratory were 0.94 and 0.86, respectively. Seropositivity averaged 52% in those aged less than one year and 60% in those between four and seven years. A higher rate of seropositivity was observed in urban versus rural children (odds ratio (OR) = 2.55), breast feeding in urban areas only (OR = 1.87), and day care versus home care setting (OR = 1.59). High CMV seroprevalence, even in the first year of life, was observed in this population of well children in Chengdu, China. An association was observed between seroprevalence and residence, method of feeding, and day care attendance.

Bottle Feeding↗