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Biomedical subjects

D Zhao

Publications and source records attributed to D Zhao.

At least 181 records · Page 10Linked to original sources
PubMed1993

Selective sympathectomy of the liver: a comparison of orthotopic liver transplantation and intraportal 6-hydroxydopamine injection.

1. Tissue noradrenaline (NA) levels correlate well with the extent of sympathetic innervation of that tissue. 2. In this study the distribution of NA throughout the different lobes of the rat liver was studied. The extent of sympathectomy by means of either orthotopic liver transplantation (OLT) (n = 7) or chemical denervation by intraportal administration of 6-hydroxydopamine (6-OH-DA) (n = 8) was examined. 3. In the normally innervated rat liver, NA was homogeneously distributed throughout the organ. Tissue NA was decreased both by OLT (> 99%) and 6-OH-DA (93%) (both P < 0.001 versus control). 4. Samples of the renal cortex and left ventricle were taken as reference tissues. OLT did not result in any change in reference tissue NA, however, 6-OH-DA decreased renal cortex NA by 93% and ventricular NA by 76%, respectively (both P < 0.01 versus OLT). 5. We conclude that OLT causes selective and complete hepatic sympathectomy but that 6-OH-DA causes incomplete denervation of the liver and significant denervation of other organs.

Animals↗
PubMed1993

Metabolism of a long-chain diacylglycerol by permeabilized A10 smooth muscle cells.

The regulatory effects of diacylglycerol (DAG) second messengers will be terminated by metabolism. A long-chain DAG, 1-palmitoyl-2-[1-14C]oleoyl-sn-glycerol (2-[14C]POG), was metabolized by cultured A10 smooth muscle cells after permeabilization by preincubation with 340 U/ml alpha-toxin from Staphylococcus aureus. In contrast to results with the cell-permeable DAG analogue, dioctanoyl-glycerol ([3H]diC8), no appreciable 2-[14C]POG degradation could be detected in control A10 cells not treated with alpha-toxin. With permeabilized A10 cells, 2-[14C]POG was mainly converted into lipolytic products of a lipase pathway, monoacylglycerol (MG) and fatty acid (FA); very little radioactivity was incorporated into triacylglycerol (TG) or phospholipid (PL) via reactions catalyzed by either DAG acyltransferase, cholinephosphotransferase, or DAG kinase. Similar results were obtained in experiments with 1-stearoyl-2-[1-14C]arachidonoyl-sn-glycerol. The conversion of 2-[14C]POG into PL and TG was not enhanced by the addition of 1 mM ATP-MgCl2, 1 mM CDP-choline, or 1 mM oleoyl-CoA to the alpha-toxin-treated A10 cells. The formation of FA and MG by permeabilized A10 cells was inhibited by DAG lipase inhibitors, U-57,908 (50 microM) and tetrahydrolipstatin (1-25 nM). The predominant contribution of the lipase pathway to the metabolism of a long-chain DAG, 2-[14C]POG, by alpha-toxin-treated A10 cells is similar to results for the degradation of [3H]diC8 by intact A10 cells.

Animals↗
PubMed1993

Orthotopic liver transplantation in the rat: comparison of models with and without rearterialization of the graft.

A total of 112 orthotopic liver transplants with (AOLT) and without (NOLT) rearterialization were performed in 2 series using male Lewis rats as donors and recipients. In the first series, the 2-week survival rates were 5/11 (45.5%) in the NOLT group and 22/31 (71%) in the AOLT group. The difference in survival was due to operative experience, as the NOLT transplants were performed before the AOLT transplants. In the second series, the NOLT (n = 30) and AOLT transplants (n = 40) were performed in random order. No differences in 2-week survival rates were found [NOLT, 29/30 (96.7%); AOLT, 37/40 (92.5%)]. Recovery of pre-operative body weight was, however, faster in the AOLT (7 days) than in the NOLT group (14 days). In the NOLT group, elevation of serum levels of GOT (p < 0.05 vs. AOLT at 3 days) and alkaline phosphatase (p < 0.01 vs. AOLT at 3 days and 1 week; p < 0.05 at 4 weeks) were found. We conclude from our results that in OLT without prolonged graft storage, survival is a sensitive marker of operative success only in the training phase. Once operative technique has been mastered, a success rate of greater than 90% should be achieved before inclusion of the animals in further scientific studies. As the AOLT animals recover body weight faster and have less evidence of liver injury up to 4 weeks post-transplantation, one is led to the conclusion that AOLT in the rat may be a better model for use in all liver transplantation research.

Alkaline Phosphatase↗
PubMed1993

Bilateral renal lymphosarcoma in a dog.

A lymphosarcoma originating from kidneys, which metastasized to the ovaries, oviducts, heart and pancreas, was pathologically diagnosed in a 3-year-old female Japanese dog (Shiba dog). Clinically, the dog exhibited vomiting, diarrhea, oliguria and abdominal enlargement, associated with hypoglycemia. Grossly, the kidneys were enlarged and neoplastic masses were also seen in the ovaries and heart. Histologically, a majority of glomeruli and renal tubules were obliterated due to diffuse invasion by tumor cells. There were no metastatic lesions in the mesenteric and tracheobronchial lymph nodes, spleen and bone marrow. Most of the tumor cells were small- to medium-sized lymphoid cells with a large nucleus and scanty cytoplasm.

Animals↗
PubMed1993

[Diagnosis and treatment of cysticercosis of cerebral ventricles].

31 patients with cysticercosis of cerebral ventricles verified by operation or pathological investigation were reported. All patients were between 7 and 64 years of age and 14 were females. All had a single cyst. Since 29 patients (94%) were without a history of intestinal taeniasis, it was proposed that most patients of cysticercosis of cerebral ventricles were caused by hetero-infection and the entrance of Cysticercus into brain ventricle was through choroid plexus along the cerebrospinal fluid. This is probably the reason why it occurs mostly in the 4th ventricle. The clinical manifestation of cysticercosis of cerebral ventricles were paroxysmal headache and vomiting caused by increased intracranial pressure. Ventriculography and CT scanning have considerable diagnostic value. Removal of Cysticercus by surgical operation is successful (Figs. 1-8).

Adolescent↗
PubMed1993

[A preliminary study of insulin resistance in essential hypertension, simple obesity and acromegaly].

Plasma glucose and serum insulin during OGTT were measured in 33 patients with essential hypertension, 17 patients with simple obesity, 19 patients with acromegaly and 10 normal adults. Compared with control, serum insulin concentration increased in 33 patients with essential hypertension at 3 hour postload (P < 0.05) and in 17 patients with simple obesity at 1 hour postload (P < 0.05) during OGTT, 19 patients with acromegaly also had their insulin concentration increased at 1.3 hour postload (P < 0.05) during OGTT. The correlationships between diastolic blood pressure and integrated area under the curve for serum insulin concentration (r = 0.3838, P < 0.05) were observed in 33 patients with essential hypertension. Serum insulin concentration decreased in 10 patients with essential hypertension at 1 and 2 hour postload during OGTT after antihypertensive treatment with captopril or captopril plus hydrochlorothiazide. The results indicated that the patients with essential hypertension, simple obesity and acromegaly are insulin resistant and hyperinsulinemic after an oral glucose load.

Acromegaly↗
PubMed1993

Morphometry of the liver after liver transplantation in the rat: significance of an intact arterial supply.

Two models of orthotopic liver transplantation in the rat currently used are with and without reconstruction of the hepatic artery. The aim of this study was to assess the importance of the arterial blood supply to liver structure after orthotopic liver transplantation with advanced morphometric methods. Orthotopic liver transplantation was performed in male Lewis rats, of which 11 underwent reconstruction of the hepatic artery and 11 did not. A group of untreated controls (n = 5) and a group of animals with hepatic artery ligation (n = 4) were included. Eight weeks after surgery liver tissue was harvested and subjected to systematic random sampling. A point-counting method was used, volume fractions of tissue components were determined. Liver samples from rats that underwent hepatic artery reconstruction had preserved lobular architecture, and estimated bile duct (0.71% +/- 0.33% [S.D.]) and connective tissue (1.89% +/- 0.52%) volumes were not significantly different from those of controls (bile duct, 0.34% +/- 0.17%; connective tissue, 0.70% +/- 0.07%). In contrast, liver samples from rats that did not undergo hepatic artery reconstruction showed bile duct proliferation (7.19% +/- 4.83%; p < 0.05) and an increase in connective tissue volume (7.54% +/- 3.68%; p < 0.05) associated with a decrease in hepatocyte volume (controls, 87.3% +/- 0.3%; rats that underwent arterialization, 85.5% +/- 1.0%; rats that did not undergo arterialization, 73.2% +/- 8.2% [p < 0.05]). Interestingly, hepatic artery ligation had no significant effect on any parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Ultrastructural study of moniliformin induced lesions of myocardium in rats and mice.

Effects of moniliformin on the ultrastructure of the myocardium of mice and rats were studied. Mice were given moniliformin orally at a dose of 29.46 mg.kg-1 the LD50. One h after dosing, lesions of the mitochondria of the myocardial cells were found which became more severe in 2 and 3 h. Ultrastructural lesions were also observed in the myofibrils and sarcolemma. Rats were given moniliformin orally at the dosage of 6 mg.kg-1 once daily for 56 d. Lesions of mitochondria and myofibrils were relatively mild. In the myocardiac specimens taken from the 21d post-toxin administration, lesions of the sarcolemma became more obvious. These moniliformin-induced lesions were similar to the ultrastructural changes in the myocardium of patients with Keshan disease. Our findings indicate that there may be a close and important relationship between moniliformin intoxication and Keshan disease.

Animals↗
PubMed1993

[The epidemiology of coronary heart disease (CHD) in 16 provinces of China. Multi-province Cooperative Group of Cardiovascular Disease Surveillance (MONICA Project)].

This paper presents the cross-section results of epidemiological survey for acute CHD event in sixteen provinces of China, using the data of Multi-province Cooperative Surveillance Study on Cardiovascular Disease (MONICA Project), 1987-1989. The results showed that there were significant differences in geographical distribution of the morbidity and of the mortality of CHD event. The northern provinces had higher rates than southern provinces. There was a positive correlation between the morbidity of CHD and the geographical altitudes. The coefficients of correlation were 0.5 and 0.57 for male and female, respectively (P < 0.05). Male had higher morbidity and mortality than female. The average sex ratio (male/female) for the morbidity was 2.20. There were higher rates in urban areas as compared with those in rural areas. There were higher case fatality rates in most provinces. The average percentage for the death out-of-hospital was 43.91% of the total number of CHD death. The percentage of death within 1 hour after onset accounted for 35.13% of the total number of CHD death. The duration from onset to death was less than 24 hours in 72.96% of the total number of CHD death. The results are of important values for the prevention, treatment and the etiologic study of CHD.

Adult↗
PubMed1992

Isolation and characterization of cDNAs encoding the rat pituitary gonadotropin-releasing hormone receptor.

Rat pituitary cDNAs encoding the full peptide coding sequence of the rat gonadotropin-releasing hormone receptor were isolated and characterized. The deduced amino acid sequence encodes a protein of 327 residues with seven putative transmembrane domains characteristic of the family of G-protein coupled receptors. It is 95% identical at the amino acid level with the mouse gonadotropin-releasing hormone receptor. An mRNA of 4.5 Kb was identified in the rat pituitary, ovary, and testis, and in murine alpha T3 cells. In addition, a larger mRNA species of 5.0-5.5 Kb was present in these rat tissues, and a smaller mRNA species of 1.8 Kb was present in the rat pituitary and ovary, and in alpha T3 cells. The receptor mRNA levels were increased in the female rat pituitary after ovariectomy compared to levels in intact female rats.

Amino Acid Sequence↗
PubMed1992

Comparison of an endogenous protein kinase C substrate in rat aorta with rat brain MARCKS.

We have compared the properties of a rat aorta-derived protein kinase C substrate (p75) with those of 80 kDa kinase C substrates from rat brain (MARCKS) and rabbit aorta (p80). Rat aortic p75 appeared to be closely related to rat brain MARCKS on the basis of: solubility in perchloric acid and trichloroacetic acid, heat stability, isoelectric point (pI approximately 4.2), overall V8 protease phosphopeptide map, and immunocrossreactivity with an antibody directed against the N-terminal domain of MARCKS. However, p75 could be distinguished from rat brain MARCKS and from the rabbit aorta-derived p80 on the basis of its consistently more rapid electrophoretic mobility in SDS-containing gels, and in terms of a unique proteolytic phosphopeptide found in MARCKS but not in aortic p75. We conclude that p75 probably belongs to the family of protein kinase C substrates represented by MARCKS, and that differences in post-translational processing (glycosylation) or mRNA processing may account for the unique properties of the p75 protein in rat aortic tissue.

Animals↗
PubMed1992

Hippocampal kindling induced paired-pulse depression in the dentate gyrus and paired-pulse facilitation in CA3.

Rats received high frequency (100 Hz, 1 s) hippocampal stimulations that evoked afterdischarges (ADs) in a partial kindling model of epilepsy. Kindled rats were given 15 ADs over 3 days. Control rats received the same stimulation pulses at 0.17 Hz (low frequency stimulation, LFSs). Subsequent to in vivo stimulations, hippocampal slices were obtained from the rats and extracellular field responses were recorded in the CA3 cell layer following CA1 stratum radiatum stimulation, and in the granule cell layer of the dentate gyrus (DG) following perforant path stimulation. At the DG, the paired-pulse facilitation of the population spike was depressed in the kindled than the control group, on 1 day or 23 days post ADs/LFSs. The excitatory postsynaptic potential (EPSP) responses in DG following single or paired pulses were not different between kindled and control slices. At CA3, paired-pulse facilitation of both the population spike and the population EPSP was increased in the kindled compared to the control group.

Animals↗
PubMed1992

A systematic comparison of three structure determination methods from NMR data: dependence upon quality and quantity of data.

We have systematically examined how the quality of NMR protein structures depends on (1) the number of NOE distance constraints, (2) their assumed precision, (3) the method of structure calculation and (4) the size of the protein. The test sets of distance constraints have been derived from the crystal structures of crambin (5 kDa) and staphylococcal nuclease (17 kDa). Three methods of structure calculation have been compared: Distance Geometry (DGEOM), Restrained Molecular Dynamics (XPLOR) and the Double Iterated Kalman Filter (DIKF). All three methods can reproduce the general features of the starting structure under all conditions tested. In many instances the apparent precision of the calculated structure (as measured by the RMS dispersion from the average) is greater than its accuracy (as measured by the RMS deviation of the average structure from the starting crystal structure). The global RMS deviations from the reference structures decrease exponentially as the number of constraints is increased, and after using about 30% of all potential constraints, the errors asymptotically approach a limiting value. Increasing the assumed precision of the constraints has the same qualitative effect as increasing the number of constraints. For comparable numbers of constraints/residue, the precision of the calculated structure is less for the larger than for the smaller protein, regardless of the method of calculation. The accuracy of the average structure calculated by Restrained Molecular Dynamics is greater than that of structures obtained by purely geometric methods (DGEOM and DIKF).

Magnetic Resonance Spectroscopy↗
PubMed1992

Phase aberration correction using echo signals from moving targets. I: Description and theory.

Inhomogeneous acoustic velocity in human tissue introduces phase aberration in ultrasonic imaging systems and degrades image quality. A novel technique that employs echo signals from moving diffuse targets, such as flowing blood, as an image quality factor to compensate for phase aberration is described. Such signals can be obtained by subtracting the images of two consecutive target interrogations. The fundamental statistics of the quality factor and other related parameters are developed to provide a theoretical basis for the technique.

Algorithms↗
PubMed1992

Phase aberration correction using echo signals from moving targets. II: Experimental system and results.

A method for correcting errors due to near-field tissue inhomogeneities in phased array ultrasound images is evaluated experimentally. The method uses the brightness of a moving speckle-generating target, such as blood, as a quality factor to correct for unknown phase aberrations. A real time experimental system utilizing the technique has been constructed and is described. Initial results from in vitro studies using a flow phantom are compared to theoretical predictions. The results indicate that the technique can provide significant improvements in image quality when imaging through aberrating media, and may find application in clinical imaging through skull and fatty layers.

Algorithms↗