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Biomedical subjects

Z H Zheng

Publications and source records attributed to Z H Zheng.

At least 19 recordsLinked to original sources
PubMed2004

Dewetting of conducting polymer inkjet droplets on patterned surfaces.

The manufacture of high-performance electronic devices with micrometre or even submicrometre dimensions by solution processing and direct printing, requires the ability to control accurately the flow and spread of functional liquid inks on surfaces. This can be achieved with the help of surface-energy patterns causing inks to be repelled and dewetted from pre-defined regions of the substrate. To exploit this principle for the fabrication of submicrometre device structures, a detailed understanding of the factors causing ink droplets to dewet on patterned surfaces is required. Here, we use hydrophobic surface-energy barriers of different geometries to study the influence of solution viscosity, ink volume, and contact angle on the process of dewetting of inkjet-printed droplets of a water-based conducting polymer. We demonstrate polymer field-effect transistor devices with channel length of 500 nm fabricated by surface-energy-assisted inkjet printing.

Hydrophobic and Hydrophilic Interactions↗
PubMed2001

Acute effects of peritoneal dialysis solutions on appetite in non-uremic rats.

BACKGROUND: Standard peritoneal dialysis (PD) solutions may contribute to anorexia in PD patients due to the peritoneal absorption of glucose from the dialysate, abdominal discomfort and other factors. New PD solutions containing alternative osmotic agents, neutral pH and bicarbonate as buffer were recently developed. To test the effect of these solutions on appetite, we investigated how intraoral (IO) intake of sucrose via an IO cannula was influenced by intraperitoneal (IP) infusion of different PD solutions in an appetite model in rats. METHODS: The IO intake was measured in male Wistar rats after an IP dwell of 30 and 120 minutes with the following PD solutions: 1.36%, 2.27% and 3.86% glucose based and lactate buffered solutions (D); 1.36%, 2.27% and 3.86% glucose based and bicarbonate/lactate buffered solutions (P); 7.5% icodextrin based solution (E); 1.1% amino acid-based solution (N); and, 2.5% glucose-based lactate-buffered solution (GB), using sham injection (injection without infusion) as control. Prior to the tests, rats were provided with an IO cannula, and were trained for two weeks until the rate of IO intake had stabilized. RESULTS: The D and N solutions inhibited IO intake. For the D solutions, the degree of appetite suppression was higher with the higher concentration of glucose. P 3.86%, but not P 1.36% and P 2.27% solutions, inhibited the IO intake. However, a comparison of the degree of appetite inhibition between D and P showed less inhibition with P 1.36%, 2.27% and 3.86% solutions than with corresponding D solutions. The E solution did not seem to suppress appetite. Finally, no significant difference in IO intake was found between rats given GB 2.5% and D 2.27%. CONCLUSIONS: In this appetite model in rats, the measurement of IO intake after the IP infusion of different dialysis solutions showed that (1) N and D solutions may reduce appetite, and for the D solutions the degree of appetite inhibition was related to the dialysate concentrations of glucose; (2) the P solutions had less impact on appetite than the D solutions; (3) the E solution had no impact on appetite during the short dwells of 30 and 120 minutes. The demonstrated differences between the different solutions appear to be due to different concentrations, and type, of nutrients used as osmotic agent (glucose, amino acids, icodextrin) or buffer (lactate), although differences in dialysate pH, tonicity and concentration of glucose degradation products also may be important. The present studies suggest a possible positive effect on appetite by using bicarbonate/lactate buffered solutions instead of lactate buffered solutions.

Administration, Oral↗
PubMed2000

Effect of dialysate composition on the apoptosis and proliferation of human peritoneal mesothelial cells and protein expression of Fas and c-Myc.

To investigate the effect of dialysate composition on apoptosis and proliferation of human peritoneal mesothelial cells (HPMCs) in vitro, HPMCs were cultured from human omental tissue. The cells were exposed for three days to culture medium containing: (1) 3.86% glucose, (2) 1.36% glucose, (3) 1.75 mmol/L Ca++, (4) 1.25 mmol/L Ca++, or (5) no additions (control). Apoptosis and proliferative cell nuclear antigen (PCNA) were measured by terminal deoxynucleotidyl transferase (TdT)-mediated in situ end-labelling and immunohistochemistry. Protein expression of Fas and of c-Myc were measured by flow cytometry. Apoptotic cells were significantly increased in the high glucose group compared to control (137 +/- 47 cells per field unit vs 63 +/- 30 cells per field unit, p < 0.01), but did not vary in the low glucose and low calcium groups versus control (76 +/- 25 cells per field unit and 77 +/- 31 cells per field unit, respectively, vs 63 +/- 30 cells per field unit, p > 0.05). Cells with positive expression of PCNA were increased in the high calcium group versus control (366 +/- 101 cells per field unit vs 186 +/- 76 cells per field unit, p < 0.01). However, the expression of PCNA was significantly more inhibited in the high glucose group than in the control group (158 +/- 52 cells per field unit vs 186 +/- 76 cells per field unit, p < 0.05). Expression of Fas was stimulated by high glucose (41% +/- 16% vs 25% +/- 8% in the control group, p < 0.05). High glucose and high calcium also up-regulated the expression of c-Myc, but only the high glucose group showed significant difference from control (39% +/- 10% vs 24% +/- 8%, p < 0.05). Our data suggest that: (1) Peritoneal dialysate could induce apoptosis of HPMCs in vitro, the degree of apoptosis depending on concentration of glucose. (2) High calcium stimulates PCNA expression by HPMCs and high glucose inhibits expression of PCNA. (3) Genes associated with apoptosis (Fas, c-Myc) might play an important role in triggering apoptosis of HPMCs.

Apoptosis↗
PubMed1999

Ethanol and lactation: effects of milk lipids and serum constituents.

To determine how chronic alcohol administration during lactation affects milk composition and the nutritional status of the dam, EtOH (3 g/kg) as a 20% solution was administered by intubation to Sprague-Dawley rats from days 2 through 15 of lactation. Control dams were pair fed to account for the reduction in food intake observed in the alcohol group, while another control group maintained ad lib food intake. Dams and their litters were weighed daily throughout the study. On day 16, dams were sacrificed and samples taken for further analysis. Blood alcohol levels as well as serum levels of calcium, cholesterol, glucose, iron, lipids, phosphorous, and triglycerides were measured. Liver lipid levels and the total composition and fatty acid profile of the phospholipids in milk were also measured. Results indicate that EtOH administration and pair feeding reduced dam body weight, but not litter growth. Serum iron levels was increased in both EtOH-exposed and pair-fed controls, whereas serum cholesterol was elevated only in EtOH-exposed dams. Finally, of the phospholipids in milk, only one, phosphatidylserine, was slightly but significantly increased by EtOH. If and how these changes impact the development of the offspring remain to be studied.

Animals↗
PubMed1999

[A study of a derivative of Taq DNA polymerase].

Using the method of double primer oligonucleotide-mediated mutagenesis, the high expression plasmid of TaqND236, a derivative of Taq DNA polymerase, was constructed. To determine the frameshift mutation frequency of the in vitro DNA synthesis, we constructed a Gapped-DNA system using the pFDPM118 (a mutant of pUC118 with a -1 frameshift mutation on the lacZ gene) as template. By calculating the ratio of blue and white colonies on the X-gal plate after transforming E. coli TG1, the frameshift mutation frequency of Taq and TaqND236 was measured. It was found that the replication fidelity of the deleted Taq-TaqND236 increased more than 10 folds.

DNA Replication↗
PubMed1999

[Correlation analysis of (G + C)% of coding sequence and thermostability of xylose isomerase of thermophiles].

Statistical analysis about amino acids and coding sequence of xylose isomerase were performed in a number of thermophiles and mesophiles. It was found that there are correlations between the (G + C)% of the coding sequence and that of 1st, 2nd and 3rd position of the code of amino acids. There were also positive (for hydrophobic amino acids) and negative (for hydrophilic amino acids) correlation between the content of individual amino acids in the enzyme protein and the (G + C)% of their respective coding sequence. It speaks for the notion that high content of (G + C) in the coding sequence tends to increase the thermostability of the corresponding protein. The results in the statistical analysis of amino acid substitutions leading to change in thermostability of the protein may also be interpreted in the same way. An increase in the (G + C)% of DNA of a bacterium can therefore not only increase the thermostability of DNA itself but its proteins as well. Evolutionary consequence concerning thermophily and coding system are discussed.

Aldose-Ketose Isomerases↗
PubMed1993

[Effects of scorpion injection on interleukin 1 and pathology in experimental glomerulonephritis in situ].

UNLABELLED: The model of experimental glomerulonephritis in situ in rats was established by administration of C-BSA. 24 male Wistar rats were randomly assigned to three groups: C-BSA, control and C-BSA+scorpion (scorpion injection, ip, 1.0 g/kg, once/day). At the end of 4th week, the bioactivity of serum IL-1 was assayed by thymocyte proliferation method and the renal pathology was checked up. Urine sample was collected for 24 hour once/week for protein determination. RESULT: Quantity of proteinuria in scorpion group was reduced significantly in comparing with C-BSA group. Level of IL-1 was significantly lower in scorpion group than that in C-BSA group. Injury of renal tissue also was mild in the treated group. These results suggested that scorpion injection could suppress the activities of IL-1 and ameliorate the pathological injury in this experimental glomerulonephritis in situ.

Animals↗
PubMed1991

Distribution of synapses on fast and slow pyramidal tract neurons in the cat. An electron microscopic study.

Distributions of synapses on various portions of fast and slow pyramidal tract neurons (PTNs) in cat motor cortex were studied with electron microscopy. PTNs were identified by their antidromic invasion following stimulation of the medullary pyramid and were classified into fast and slow PTNs according to conduction velocities of their axons. Two fast and two slow PTNs were intracellularly labeled and, by systematic sampling, electron micrographs from various portions of these neurons were examined to compare the distributions of different types of synapses. It was found that most synapses formed on apical and basal dendrites of fast PTNs were with the dendritic shafts. In slow PTNs, while synapses on apical dendrites were mostly axospinous, about 70% of the sampled synapses on basal dendrites of slow PTNs were established with the dendritic shafts. Virtually all synapses on apical dendrites of slow PTNs belonged to asymmetrical type and most of the synapses sampled from basal dendrites of fast PTNs were also asymmetrical. On the other hand, about 29% of the synapses found on apical dendrites of fast PTNs were symmetrical and a trend was observed for this type of synapses to increase their number with increasing proximity to the cell body. Over 28% of the synapses on basal dendrites of slow PTNs were also symmetrical and seemed to be mainly distributed in layer VI. All synapses formed on the soma were symmetrical both for the fast and slow PTNs.

Animals↗
PubMed1991

Distribution of synapses on an intracellularly labeled small pyramidal neuron in the cat motor cortex.

The morphological characteristics and distribution of synapses on a small pyramidal neuron in layer III of the cat motor cortex have been studied by combining intracellular HRP staining and electron microscopic examination. The stained neuron showed spiny apical and basal dendritic profiles under the light microscope, and exhibited the morphological features of a pyramidal neuron. Ultrastructural analysis indicated that about 80% of the presynaptic terminals formed asymmetrical synapses with spines of distal apical and basal dendrites. On proximal apical dendrites, 64% of the synapses were found to make contact with spines, and 16.7% of the synapses were of symmetrical type and formed with dendritic shafts. Two types of terminal could be identified on the soma; they were alternately located and established symmetrical and asymmetrical synaptic contacts respectively. Possible functional implications are discussed.

Animals↗
PubMed1989

Metabolic derangement of glucose, bile acid and amino acids after portasystemic shunts in cirrhotic rats.

Carbon tetrachloride was used to induce cirrhosis in 81 Wistar rats. The animals were divided into three groups to receive end-to-side mesocaval shunt (MCS), end-to-side portacaval shunt (PCS) and Sham operation as control, respectively. Dynamic values of blood glucose and hormones for regulating glucose metabolism, SGPT, serum glycine conjugated cholic acid (CCA) and free serum amino acids were determined and compared with those obtained from 10 normal rats. The determinations suggested that the insulin level depended on the severity of hepatocellular damage with hyperglucagonemia after portasystemic shunt, and CCA was markedly elevated in MCS rats after interruption of the enterohepatic circulation. Changes of CCA were also influenced by hyperglucagonemia and poor liver function in PCS rats. Increase in the aromatic amino acids (AAA) level was related to the impaired hepatic function and hyperglucagonemia. However, decrease in the branched-chain amino acids (BCAA) level was not likely in response to the serum insulin level. Therefore, it is concluded that imbalance of serum amino acids has partial relationship with the derangement of glucose metabolic hormones.

Amino Acids↗
PubMed1986

Thalamic projection to motor area and area 3a of the cat cerebral cortex.

The distributions of thalamic neurons projecting to the motor cortex and cortical area 3a were studied in cat by means of the retrograde double-labeling technique using Nuclear Yellow (NY) and Fast Blue (FB) as tracers. Following injection of NY and FB into the motor cortex and area 3a respectively, the NY-labeled neurons were found to be mainly located in ventrolateral (VL) nucleus and FB-labeled neurons in ventro-posterolateral nucleus (VPL). However, these two kinds of neurons were intermingled with each other in the border area between VL and VPL. A small number of neurons were double-labeled by both NY and FB. They were also distributed in the border area. Some of them could often be found in centromedian and parafascicular nuclei.

Animals↗
PubMed1986

Direct synaptic linkage of ventrolateral nucleus of thalamus terminal with cat fast pyramidal tract neuron.

An electron microscopic study on the synaptic connections between neurons of ventrolateral nucleus of thalamus (VL) and pyramidal tract neurons (PTNs) in cat motor cortex was conducted by means of the anterograde degenerating procedure coupled with horseradish peroxidase (HRP) intracellular staining. Following VL lesions, a large majority of the degenerating terminals were found to terminate on dendritic spines and a few on the dendritic shaft. An asymmetric type synapse formed by a VL degenerating terminal and the dendritic shaft of a branch of apical dendrite of a labeled fast pyramidal tract neuron was demonstrated.

Animals↗
PubMed1984

Are hypothalamo-cerebellar fibers collaterals from the hypothalamo-spinal projection?

Retrograde transport of fluorescent tracer molecules (Fast Blue and Nuclear Yellow) was used to restudy the feline hypothalamo-cerebellar and hypothalamo-spinal projections in order to decide whether hypothalamo-cerebellar and hypothalamo-spinal fibers are branches of the same axons. The finding of a significant hypothalamo-cerebellar projection from lateral, dorsal and posterior hypothalamic areas is confirmed. Scattered hypothalamo-cerebellar fibers were found to come from the supraoptic, dorsomedial, periventricular, infundibular and paraventricular nuclei, tuber cinereum and the anterior hypothalamic area. A topographical organization is proposed for the hypothalamo-cerebellar projection; the cerebellar anterior lobe receives fibers mainly from the rostral (anterior) hypothalamus while the posterior lobe receives fibers mainly from its caudal (posterior) part. The hypothalamo-spinal pathway originates principally within the dorsal, posterior and lateral hypothalamic areas, but receives small contributions also from the periventricular and paraventricular nuclei, tuber cinereum and the anterior hypothalamic area. Hypothalamic neurons retrogradely labeled from the spinal cord and from cerebellum were often located adjacent to each other, but only few double labeled neurons were found. This indicates that spinal and cerebellar projecting cells are mainly two different populations.

Animals↗