Biomedical subjects

J Zhao

Publications and source records attributed to J Zhao.

At least 451 records · Page 25Linked to original sources

PubMed1998

Carteolol is a weak partial agonist on beta 3-adrenergic receptors in brown adipocytes.

The ability of the beta 1/beta 2 partial agonist carteolol to act as an agonist on beta 3-adrenergic receptors was investigated by studying its ability to stimulate thermogenesis (oxygen consumption) in brown fat cells isolated from hamsters. Carteolol was able to induce thermogenesis, with an EC50 of 5 microM, but it was only a partial (40%) agonist. D,L-Propranolol had a pKB of 5.1 as an antagonist against carteolol in this system, indicating that the carteolol effect was probably mediated via beta 3-receptors. Also in mouse and rat cells, carteolol was a partial agonist with EC50 values around 1 microM. Being a partial agonist, carteolol acted as an antagonist against norepinephrine-, BRL-37344-, or CGP-12177-stimulated thermogenesis with a pKB of approximately 5. The partial agonist effects of carteolol are discussed in relation to the absence of agonist effect of this compound on guinea-pig taenia cecum beta 3-receptors and in relation to the possible plurality of beta 3-receptors.

Adipose Tissue, Brown↗

PubMed1998

Nicotine stimulates branching and expression of SP-A and SP-C mRNAs in embryonic mouse lung culture.

Although the effects of maternal smoking on fetal growth and viability are overwhelmingly negative, there is a paradoxical enhancement of lung maturation as evidenced, in part, by a lower incidence of respiratory distress syndrome in infants of smoking mothers. Other epidemiologic and experimental evidence further support the view that a tobacco smoke constituent, possibly nicotine, affects the development of the lung in utero. We are studying the direct effects of nicotine on murine lung development using a serumless organ culture system. We have found that embryonic lungs explanted at 11 days gestation showed a 32% increase in branching after 4 days in culture in the presence of 1 microM nicotine and 7- to 15-fold increases in mRNAs encoding surfactant proteins A and C after 11 days. The effect of nicotine exposure on surfactant gene expression is apparently mediated by nicotinic acetylcholine receptors because it was blocked by D-tubocurarine. The nicotine-induced stimulation of surfactant gene expression could, in part, account for the effect of maternal smoking on the incidence of respiratory distress syndrome.

Animals↗

PubMed1998

Inhibition of vascular and epithelial differentiation in murine nitrofen-induced diaphragmatic hernia.

Neonates with congenital diaphragmatic hernia (DH) die of pulmonary hypoplasia and persistent pulmonary hypertension. We used immunohistochemical localization of alpha-smooth muscle actin (alpha-SMA), platelet endothelial cell adhesion molecule (PECAM)-1, thyroid transcription factor (TTF)-1, surfactant protein (SP) A, SP-C, and competitive RT-PCR quantitation of TTF-1, SP-A, SP-C, and alpha-SMA mRNA expression to characterize the epithelial and vascular phenotype of lungs from ICR fetal mice with a nitrofen-induced DH. Nitrofen (25 mg) was gavage fed to pregnant mice on day 8 of gestation. Fetal mice were delivered on day 17. The diaphragm was examined for a defect, and the lungs were either fixed, sectioned, and immunostained or processed for mRNA isolation. In comparison with control lungs, DH lungs showed increased expression of alpha-SMA mRNA, fewer and more muscular arterioles (alpha-SMA), less well-developed capillary networks (PECAM-1), delayed epithelial development marked by a persistence of TTF-1 in the periphery, and decreased SP-A mRNA and SP-A expression. These data suggest that in the murine nitrofen-induced DH, as in human congenital DH, pulmonary insufficiency is due to an inhibition of peripheral pulmonary development including terminal airway and vascular morphogenesis.

Actins↗

PubMed1998

Apparent thermogenic effect of injected glucagon is not due to a direct effect on brown fat cells.

To examine the significance of brown adipose tissue for the thermogenic response to glucagon, we injected glucagon intraperitoneally into rats (that have glucagon-sensitive brown fat cells) and into hamsters (that have glucagon-insensitive brown fat cells). Although a thermogenic response to glucagon injection was apparently observed in rats, this response was not augmented by cold acclimation and was not dose dependent. Similar observations were made in hamsters. The thermogenic response could be fully blocked by prior injection of the beta-adrenergic blocker propranolol. Thus no direct thermogenic response to injected glucagon could be demonstrated, and the thermogenic response observed was fully due to vehicle injection. However, glucagon injection was able to unmask mitochondrial [3H]GDP binding. As expected, isolated brown fat cells from rats and mice responded thermogenically to glucagon but brown fat cells from hamsters were unresponsive. The EC50 of the rat brown fat cells was high (5 nM); these cells also responded to secretin, with an EC50 of 22 nM. It was concluded that, in contrast to earlier observations, no thermogenic response to injected glucagon could be observed; this may be related to differences in glucagon preparations. Brown fat cells from certain species are, however, glucagon sensitive. It is uncertain whether glucagon is the endogenous agonist for these receptors, but the presence of the glucagon-responsive receptor indicates alternative means to norepinephrine for stimulation of brown adipose tissue thermogenesis and, probably, of recruitment.

Adipose Tissue, Brown↗

PubMed1998

Thermogenesis is beta3- but not beta1-adrenergically mediated in rat brown fat cells, even after cold acclimation.

To examine if acclimation of rats to cold led to alterations in the coupling between different beta-receptor subtypes and thermogenesis in brown fat cells, we investigated the adrenergic response patterns in brown fat cells isolated from warm-acclimated (28 degreesC) and cold-acclimated (4 degreesC) rats. In the cells from warm-acclimated rats, the relative affinities (EC50) for different agonists (isoprenaline, BRL-37344, norepinephrine, CGP-12177, dobutamine, and salbutamol) were those expected from their interaction with a beta3-receptor. The response to norepinephrine was competitively inhibited by propranolol with a pA2 of approximately 6, implying interaction at the beta3-receptor. No evidence for a beta1-receptor-mediated response to the beta1-selective agonist dobutamine could be obtained; the low-affinity response observed was most likely through the beta3-receptor. The beta1-antagonist ICI-89406 could not inhibit a specific fraction of the thermogenic response to norepinephrine. Thus beta3-receptors were the only beta-receptors involved in the control of thermogenesis in brown fat cells from warm-acclimated rats. A modified method of preparation was developed to isolate functional cells from cold-acclimated animals. Also in these cells, the beta-receptor coupled to thermogenesis was the beta3-receptor, although the response was desensitized with an approximately sevenfold shift in EC50 values. The pA2 for propranolol inhibition of norepinephrine-induced thermogenesis was also 6 here, and that for ICI-89406 was 5.5, also implying interaction at the beta3-receptor. Thus acclimation to cold did not alter the beta-adrenergic receptor subtype (beta3) involved in the control of thermogenesis.

Acclimatization↗

PubMed1998

The Shc 66 and 46 kD isoforms are differentially downregulated at parturition in the fetal mouse lung.

Many of the signaling pathways regulating fetal lung mesenchymal cell proliferation are mediated by the Shc intracellular signaling proteins. Shc is expressed as three isoforms: 52 kD and 46 kD proteins (Shc 52 and Shc 46, respectively) translated from the same mRNA, and a 66 kD form (Shc 66) translated from a separate mRNA. Shc 52 is an activator of Ras and mitogen-activated protein kinase, whereas Shc 66 antagonizes Ras activation. The function of Shc 46 is unclear. We hypothesized that the Shc isoforms are differentially regulated during fetal mouse lung morphogenesis. Relative Shc 66 and Shc 46 protein expression are high until parturition (term = 18.5 d), when a dramatic decrease begins; by postconceptual d 20, relative Shc 66 and Shc 46 expression have fallen by 75 and 69%, respectively. A similar pattern of decreasing Shc 66 mRNA expression in the peripartum period was detected by reverse transcription and competitive polymerase chain reaction during the same period. By isoform-specific immunohistochemistry, Shc 66 is widely distributed in the embryonic lung but becomes restricted to the bronchial smooth muscle and overlying epithelia, periarterial smooth muscle, and the interlobar pleura late in gestation. After parturition, Shc 66 is virtually absent from the lung. All three Shc isoforms are phosphorylated by epidermal growth factor stimulation in fetal lung mesenchymal cells, indicating that Shc 66 is functional in these cells. These data indicate that Shc isoforms are differentially regulated during lung development.

3T3 Cells↗

PubMed1998

Megalin (gp330): a putative endocytic receptor for thyroglobulin (Tg).

Megalin (gp330) is a large glycoprotein receptor found mainly on a group of absorptive epithelial cells, including renal proximal tubule, epididymal and thyroid cells. Megalin has been shown to bind multiple, unrelated ligands, mainly in vitro, and to mediate endocytosis of ligandsin cultured cells. However, physiologic ligands of megalin are largely unknown. In the present study we have demonstrated that purified rat megalin binds rat thyroglobulin (Tg) in solid phase assays, with anestimated Kd of 9.2+/-0.6 nM. Binding was calcium dependent and was almost completely inhibited by excess Tg, by three megalin ligands - lactoferrin, lipoprotein lipase and apolipoprotein J- and by the receptor associated protein (RAP), which inhibits binding of all megalin ligands. Three anti-megalin antibodies partially inhibited Tg binding to megalin. 125I labeled Tg bound to megalin was released by EDTA and heparin; the released product was shown by SDS-PAGE and autoradiography to be 660 kD (dimeric) Tg. However, an immunoblotting experiment showed binding of megalin both to monomeric (330 kD) and dimeric Tg. We propose that megalin, which is known to mediate ligand endocytosis and is found on the apical surface of thyrocytes, may participate in the endocytosis of Tg from the colloid, a process that is required for hormone release from Tg.

Animals↗

PubMed1998

Trabecular bone mineral and calculated structure of human bone specimens scanned by peripheral quantitative computed tomography: relation to biomechanical properties.

The relationship of cortical bone mineral density (BMD), and geometry to bone strength has been well documented. In this study, we used peripheral quantitative computerized tomography (pQCT) to acquire trabecular BMD and high-resolution images of trabeculae from specimens to determine their relationship with biomechanical properties. Fifty-eight human cubic trabecular bone specimens, including 26 from the vertebral bodies, were scanned in water and air. Trabecular structure was quantitated using software developed with Advanced Visual Systems interfaced on a Sun/Sparc Workstation. BMD was also obtained using a whole-body computerized tomography scanner (QCT). Nondestructive testing of the specimens was performed to assess their elastic modulus. QCT and pQCT measurements of BMD of specimens in water were strongly correlated (r2 = 0.95, p < 0.0001), with a slope (0.96) statistically not significantly different from 1. Strong correlations were found between pQCT measurements of specimens in water and in air, for BMD (r2 = 0.96, p < 0.0001), and for apparent trabecular structural parameters (r2 = 0.89-0.93, p < 0.0001). Correlations were moderate between BMD and apparent trabecular structural parameters (r2 = 0.37-0.64, p < 0.0001). Precision as coefficient of variation (CV) and standardized coefficient of variation (SCV) for these measurements was < 5%. For the vertebral specimens, the correlation was higher between elastic modulus and BMD (r2 = 0.76,p < 0.0001) than between elastic modulus and apparent trabecular structural parameters (r2 = 0.58-0.72, p < 0.0001), while the addition of apparent trabecular nodes and branches to BMD in a multivariate regression model significantly increased the correlation with the elastic modulus (r2 = 0.86, p < 0.01). Thus, pQCT can comparably and reproducibly measure trabecular bone mineral in water or air, and trabecular structure can be quantitated from pQCT images. The combination of volumetric BMD with trabecular structural parameters rather than either alone improves the prediction of biomechanical properties. Such a noninvasive approach may be useful for the preclinical study of osteoporosis.

Adult↗

PubMed1998

[Verification and epidemiological study on endemic iodide-induced goiter in Jiangsu Old Yellow River flooded plain].

To verify the existence and reveal the epidemiological characteristics of endemic iodide-induced goiter in Jiangsu Old Yellow River flooded plain, 12 spots were selected in this survey. The results showed that the total goiter rate of 22.18% by palpation and 12.83% by B-ultrasound which surpassed the 5%-cutpoint-recommended jointly by WHO/UNICEF/ICCIDD. The urinary iodine median was 962 micrograms/L in 607 samples. The average 24 hours I31iodine-emissivity ratio was 4.6 +/- 0.3% with most of the serum TSH, T4, T3 within normal ranges. Of 1049 water samples in 65 towns, 771 had iodine content over 300 micrograms/L with water iodine concentration over 300 micrograms/L in 52 towns. These findings suggested that goiter in this plain had been endemic which related to excessive iodine in shallow well water. Heavy load of iodine over general population was noticed.

Child↗

PubMed1998

[Changes in trace elements contents of renal cells in cadmium poisoning].

OBJECTIVE: To understand the possible role of trace elements in renal damage caused by cadmium poisoning and its mechanism. METHODS: An experimental animal model with renal damage caused by cadmium poisoning was prepared, and trace elements contents in subcellular components in renal cells, lipid peroxidation reaction, renal function and its ultrastructural changes were determined. RESULTS: Uptake of cadmium could cause transfer of copper, zinc and manganese mainly distributed in the mitochondrion to cell nuclei and cytoplasm, and content of selenium and activity of glutathione-peroxidase (GSH-px) in cytosol declined and content of propandiolal increased. CONCLUSION: It suggests that changes in trace elements contents, especially in selenium content, during renal damage caused by cadmium poisoning, could correlate with the increase of lipid peroxidation, and abnormal subcellular distribution of trace elements was one of the important roles in renal damage caused by cadmium poisoning.

Animals↗

PubMed1998

A clinical trial of tang shen ning for treatment of diabetic nephropathy.

This paper reports the clinical trial of Tang Shen Ning ([symbol: see text], TSN) for treating diabetic nephropathy (incipient and clinical, as divided by Mogensen). The results showed that the total effective rate in treatment group (TSN + western medicine) was 90.0%, and that in the control group (simply with western medicine), 56.7%. TSN plays important roles in decreasing proteinuria and improving renal functions.

Adult↗

PubMed1998

Effects of some factors on callus growth and flavonoids formation in callus cultures of Saussurea medusa.

The effects of some physical and chemical factors on callus growth and flavonoids formation in callus cultures of Saussurea medusa Maxim were studied. The optimal temperature for callus growth and flavonoids formation were 25 degrees C. Flavonoids formation were greatly inhibited under dark condition, and stimulated by white light. Callus growth was promoted when 1 mg/L NAA and 0.2 mg/L KT were added to the media. The combination of 5% sucrose and 1% glucose was useful for callus growth and flavonoids formation. A fine callus strain of S.medusa was selected through irradiation with 4000 Gy of gamma-ray. The growth rate and flavonoids content of the callus strain were high and stable. Sensitive and rapid methods of high-performance liquid chromatography as well as UV spectrophotometry were developed for detecting the flavonoids in cultured cells. The results revealed that the content of total flavonoids in dry cells under white light condition was 3.2%, 4.4 times more than under dark condition and the control of flavonoids in dry cell culture at 25 degrees C was 2.02% which was 5 and 3.2 times more than those cultured at 20 degrees C and 35 degrees C respectively.

Carbon↗

PubMed1998

[Investigation of intrauterine microbes after intrauterine operation].

OBJECTIVE: To explore the postoperative changes in the cultures of ureaplasma urealyticum (UU), mycoplasma hominis (Mh), L-form bacteria (L-form), anaerobic bacteria (Ana) and chlamydia trochomatis (CT) after intrauterine operation. METHODS: Four groups of patients were set up: group 1, induced abortion; group 2, intrauterine device (IUD) insertion; group 3, penicillin i.m. after IUD insertion; group 4, oral lincomycin after IUD insertion. Intrauterine secretion were aspirated to identify the above microbes before operation and within 1 week of ending of menstrual bleeding for 4 consecutive postoperative cycles. Bacteria-carrier was defined as at least one of the 5 microbes detected. RESULTS: No difference was shown in the incidence of bacteria-carrier (IBC) among the 4 groups preoperation. The IBC tended to be the highest in the first menstrual cycle postsurgery in all the 4 groups, then decreased. Compared with preoperation, there were significantly higher IBC in the 3 IUD groups (P < 0.05) except group 1. CONCLUSION: IUD is a major factor for intrauterine microbes existing after operation, and the natural body defense system can help to get rid of the organism by time. Small doses and short period of penicillin or lincomycin administration proved not effective in clearing the intrauterine microbes after IUD insertion.

Abortion, Induced↗

PubMed1998

[The LDL receptor activity of hepatocytes during cholesterol gallstone formation in rabbits].

In order to study the mechanism of cholesterol gallstone formation through rabbit model which was induced by high cholesterol diet, we investigated the LDL receptor activity of hepatocytes binding to 125I-LDL in different phases, namely 1, 2, 3 week group and 4 week, and in a control group besides. In this animal experiment, cholesterol gallstones were induced at 2 week, 3 week and 4 week groups in 4/10, 6/10, and 7/10 cases respectively. The Bmax values of LDL receptor of hepatocytes binding to 125I-LDL decreased significantly in 3 week and 4 week groups (vs 1 week and control groups, P < 0.05). The kd values became increased in 3 week and 4 week groups (vs 1 week and control group, P < 0.05), which suggested that the activity of LDL receptor decreased gradually. In conclusions owing to the intake of high cholesterol diet with the passage of time, the decreased activity of LDL receptor of hepatocytes would reduce the synthesis of bile acid.

Animals↗

PubMed1998

[Expression of P62c-myc protein in breast cancer and its clinical significance].

The objective of this study was to determine the clinical significance of P62c-myc protein expression in breast cancer. P62c-myc protein was detected in 107 patients with breast cancer by immunohistochemical techniques (LSAB). The results showed that the positive rate of P62c-myc protein expression was 63.55% (68/107). The overexpression of P62c-myc protein related negatively with survival. 94.00% of the cases with overexpression of P62c-myc protein survived < or = 5 years, 65.00% survived > 5 years-< 10 years, and 21.62% survived > or = 10 years. There were significant associations of P62c-myc expression with advance clinical stage, high histological grade, and positive axillary node status in breast cancers. All of these findings suggested that overexpression of P62c-myc might be an important prognostic factor, and the detection of P62c-myc protein might be arranged as a regular pathological examination in the cases of breast cancer.

Adolescent↗

PubMed1998

[The analysis of the causes of postoperative deaths in intracranial meningiomas in the elderly department of neurosurgery].

OBJECTIVE: Analysis the postoperative death reason of elderly patients with meningioma. METHOD: We analysised the death reason of 18 elderly patients with meningioma who died after operation in recent 16 years, Reviewing of document is also included in this review study. RESULT: 7 patients died of postoperative cerebral infarction (3 cases sufferd heamorrage of gastric-instinal tract). 3 cases died of cardiac infarction. 2 cases renal failure and 2 cases preoperative cerebral hernia. 1 case inhalant pneumonia, 1 case postoperative cerebral hematoma, 1 case hypothamamus injury and 1 case respiration failure. CONCLUSION: Operation is not prompt to patients whose KS scale is less than 50.

Acute Kidney Injury↗

PubMed1998

[Direct surgical clipping the carotid-ophthalmic aneurysms through a extradural-intradural approach].

OBJECTIVES: To exlore the approach for treating carotid-ophthalmic aneurysms and introduce experience in reducing postoperative complications. METHODS: We treated 31 patients with carotid-ophthalmic aneurysms, which accounted for 8.3% of all intracranial aneurysms we encountered in 1994 and 1997, by direct surgical clipping. RESULTS: No operative death occurred and the rate of postoperative complications was 19%. All aneurysms were occluded and later confirmed by angiography. CONCLUSION: The direct clipping of aneurysms involving the carotid-ophthalmic artery is best treated by the extradural-intradural approach.

Adolescent↗

PubMed1998

[Expression of integrin alpha 5, beta 1 subunit and fibronectin mRNAs in human hepatocellular carcinoma].

OBJECTIVE: To study the biologic significance of the expression of integrin alpha 5, beta 1 subunit and fibronectin (FN) mRNAs in hepatocellular carcinoma (HCC). METHODS: Integrin alpha 5, beta 1 subunit and FN mRNAs were detected by using Northern blot (alpha-32P-labeled cDNA probes) and in situ hybridization (Dig-labeled cDNA probes) in 15 cases of HCC, 5 cases of paracancerous cirrhotic liver and 3 cases of normal liver tissue. RESULTS: In well-differentiated HCC, the level of integrin alpha 5, beta 1 or FN mRNA expression was similar to those in normal liver and paracancerous cirrhotic liver tissues, but was markedly decreased, even absent in the poorly- and moderately-differentiated HCC tissues (P < 0.01, respectively). The expression of integrin alpha 5 and FN mRNAs was mainly detected in the cytoplasm of HCC cells. In all the HCC cases tested, the expression of integrin alpha 5, beta 1 and FN mRNAs was lower in 8 cases of HCC with focal invasion and/or intrahepatic metastasis than that in the others without invasion or metastasis(P < 0.05). In addition, the heterogeneous expression of FN mRNA was found in 5 cases of HCC with intrahepatic metastasis. CONCLUSIONS: Combined with the immunohistochemical observation before, it might be deduced that the changes of integrin alpha 5 beta 1 and FN protein expression in HCC tissues are because of changing of the mRNA levels related, which might deeply influence the cell differentiation, tumor invasion and metastasis of HCC. The appearance of the heterogeneous FN mRNA and its encoded FN protein might be associated with the development of HCC metastasis.

Carcinoma, Hepatocellular↗