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Biomedical subjects

M Zhu

Publications and source records attributed to M Zhu.

At least 289 records · Page 16Linked to original sources
PubMed1990

High performance isoelectric focusing using capillary electrophoresis instrumentation.

High performance isoelectric focusing in capillaries provides rapid, high resolution separation of proteins based on their isoelectric points. Results can be obtained in a matter of minutes with little or no sample preparation. The technique requires the use of coated capillaries to reduce electroendosmosis so that stable, focused zones can be attained. Once focused, protein zones may be mobilized by the addition of salt to the catholyte or anolyte buffer. On-tube UV monitoring enables direct detection of sample components during mobilization with mass sensitivity equal to that of silver staining. The linear relationship between mobilization time and isoelectric point allows the technique to be used for estimation of protein pI. Demonstrated applications include separation of proteins in biological fluids with possible clinical applications, and characterization of biopharmaceutical proteins and monoclonal antibodies.

Capillary Action↗
PubMed1990

[SEM study of invasive characteristics of colorectal cancer].

This paper reports the results of a study on the invasive characteristics of 22 colorectal cancer by scanning electron microscopy (SEM). The results showed that adenocarcinoma cells stretching polymorphic pseudopodia penetrated into peripheral tissue and adhered to or invaded the vessels, but most of the mucoid carcinoma cells migrated separately into the tissue clefts and invaded the vessels. The invasive mode had dominant differentiation in two typical cancer. The author believes that colorectal cancer possesses two invasive factors: ameboid movement and destroying tissues by lysozyme.

Adenocarcinoma, Mucinous↗
PubMed1990

[A study on the methods for correcting the error in measurement of children blood pressure].

The blood pressures of a group of children was obtained with sphygmomanometer cuffs of varying widths. It was suggested that the cuff width can be effect for accuracy of blood pressure determination, then a correct formula of blood pressure determination using an inadequate cuffs was calculated. The efficacy and feasibility of the formula was tested in another two groups of children. The production of the formula made a possibility for practicing the proposal of American Heart Association in which the width of an adequate cuff was believed to be 40% of the circumference in middle arms. The formula was simple and convenient and should be used in childhood prophylactic medicine, healthy care especially in popularized measurement of children blood pressure and scientific cooperative investigation.

Blood Pressure Determination↗
PubMed1989

Alterations in cellular calcium and magnesium during circulatory/septic shock.

Hepatic cellular and mitochondrial Ca2+ and Mg2+ contents and the role of these ions in cellular dysfunction were studied in rat hemorrhagic and endotoxic models which simulate various facets of human circulatory/septic shock states. Hemorrhagic shock was induced by bleeding rats to a state of vascular decompensation at the mean arterial pressure of 40 mm Hg. Endodotoxic shock was ascertained after observing hypoglycemia, hyperlacticacidemia and hemorrhagic bowel lesions in rats injected with Salmonella enteritidis endotoxin (15-20 mg/kg). In a late stage of hemorrhagic shock, significant changes occurred in mitochondrial ion contents; Ca2+ increased and Mg2+ decreased as compared to controls. These ionic changes were correlated with depressed mitochondrial respiratory functions. Addition of 6 mM Mg2+ to shocked-rat isolated mitochondria significantly restored mitochondrial functions. In endotoxic shock, hepatic Mg2+ content was significantly lower compared to controls. Treatment of rats with the calcium antagonist, diltiazem, several minutes prior to endotoxin injections, resulted in restoration of hepatic cellular Mg2+ to control levels. Studies of hepatic intracellular Ca2+ regulation in endotoxic shock revealed (1) an elevation in free cytosolic Ca2+, (2) a blunting of catecholamine-mediated increase in cytosolic Ca2+ and (3) an inhibition of intracellular messenger-induced Ca2+ release by the endoplasmic reticulum.

Animals↗
PubMed1988

On the generalization of the Weinbaum-Jiji bioheat equation to microvessels of unequal size; the relation between the near field and local average tissue temperatures.

The extensive series of experiments reported in Lemons et al. [1] show that measureable local tissue temperature fluctuations are observed primarily in the vicinity of the 100-500 micron countercurrent vessels of the microcirculation and thus strongly support the basic hypothesis in the new bioheat equation of Weinbaum and Jiji [2] that these countercurrent microvessels are the principal determinants of local blood-tissue heat transfer. However, the detailed temperature profiles in the vicinity of these vessels indicate that large asymmetries in the local temperature field can result from the significant differences in size between the countercurrent artery and vein. Using the superposition techniques of Baish et al. [9], the paper first presents a solution to the classic problem of an unequal countercurrent heat exchanger with heat loss to the far field. This solution is then used to generalize the Weinbaum-Jiji bioheat equation and the conductivity tensor that appears in this equation to vessels of unequal size. An asymptotic analysis has also been developed to elucidate the relationship between the near field temperature of the artery-vein pair and the local average tissue temperature. This analysis is used to rigorously prove the closure approximation relating the local arterial-venous temperature difference and the mean tissue temperature gradient which had been derived in [2] using a more heuristic approach.

Arterioles↗
PubMed1986

Microskin grafting. I. Animal experiments.

This article reports a new grafting technique--microskin grafting. These experiments were carried out in rabbits, and used a small amount of autograft minced into tiny pieces and then spread on a piece of homograft. The combined autograft plus homograft was then transplanted onto the wound of a rabbit. In 12 rabbits, the microskin grafts took well and covered the wound completely in 8 rabbits. The expansion ratios of the micrografts were from 7:1 to 15:1. The healing time of the wound was from 19 to 35 days. The operation failed in 4 rabbits because of the homograft moving. Histological sections revealed that microskin grafts orientated upwards can grow well and those orientated in a lateral or downward direction can grow too. This technique is an effective procedure for repairing extensive wounds with smaller donor sites.

Animals↗
PubMedDate not supplied

A DNA hybridization assay for use in drug sensitivity tests in vitro for Plasmodium falciparum under field conditions.

A deoxyribonucleic acid (DNA) hybridization technique was applied to in vitro drug sensitivity testing of P. falciparum using a synthetic 21-mer oligonucleotide coupled to alkaline phosphatase (PFR1-AP) to monitor development of parasite stages in culture. The density of the coloured spot clearly distinguished schizonts from ring forms. This assay system was applied in the field on Hainan Island, China. Blood samples obtained from patients were cultivated in the presence of antimalarial drugs and the minimum drug concentration required to inhibit development of parasites was determined by the DNA hybridization assay and by microscopical observation of Giemsa-stained blood smears. The 2 methods yielded identical results, indicating that the DNA hybridization assay can be used for in vitro drug sensitivity testing under field conditions.

Animals↗
PubMedDate not supplied

Recombinant human Fab antibody fragments to HIV-1 Rev and Tat regulatory proteins: direct selection from a combinatorial phage display library.

A human Fab phage display library has been produced from peripheral blood lymphocytes of an individual who was asymptomatic after 10 years of infection with human immunodeficiency virus type-1 (HIV-1). The library was panned against the HIV-1 Rev and Tat regulatory proteins and several clones, producing Fab binding to these proteins, were isolated (3 to Rev and 4 to Tat) with binding constants varying from 10(-6)M to 10(-8)M. DNA sequencing demonstrated two unique anti-Rev Fab clones, but the four anti-Tat Fab comprised only two unique IgG1 heavy chain Fd fragments, illustrating redundancy of light chains. Peptide mapping of the epitopes recognized by these Fab indicated that three of the anti-Tat Fab were directed to the functional domain between amino acid residues 22-33 of the Tat molecule, and that binding was inhibited by reduction of this cysteine-rich region with dithiothreitol. The anti-Rev Fab were directed to sites adjacent to the Rev basic nucleolar localization sequence (residues 52-64) and to the Rev activation domain (residues 75-88). Binding constants were of a similar order to that of an anti-Rev single-chain Fv fragment (SFv) used successfully for intracellular immunization, and as such intracellular effects with the human anti-Tat and anti-Rev Fab are not precluded. These newly described human antibody fragments to HIV-1 regulatory proteins may be critical moieties for gene therapeutic protocols, to control HIV-1 replication in human cells.

Amino Acid Sequence↗
PubMedDate not supplied

Multiplanar variations in the structural characteristics of cancellous bone.

A quantitative serial sectioning technique and a video-imaging procedure were used to obtain precise (20-microns voxels, in a 5 mm x 6 mm x 7 mm test volume) digital images of lumbar vertebral cancellous bone specimens. Conventional stereological image analyses were performed on this data to determine multiplanar (bulk) and surface planar variations in cancellous structural properties. Based upon an error analysis of subgroups of the complete serial planar images, our findings suggest that, for a plane resolution of 20 microns, sectioning at an increment < or = 100 microns along an axis is necessary to obtain accurate data of bulk structural properties of cancellous bone. Planar structural variations obtained from the serial sections of cancellous bone revealed a high degree of complexity and heterogeneity of the bone architecture. Bone area centers deviated from the section centroid and showed a helical variation along the primary or superior--inferior loading axis of samples. In comparison with the base planes (perpendicular to the superior-inferior axis), the lateral planes (parallel to the superior-inferior axis) of spine samples showed smaller mean values of structural indices and a more oriented structure. This structural anisotropy may be related to the functional mechanical anisotropy of the samples.

Adult↗
PubMedDate not supplied

A mechanistic assessment of 1,3-butadiene diepoxide-induced inhibition of uterine deciduoma proliferation in pseudopregnant rats.

Butadiene diepoxide (BDE), a reactive metabolite of 1,3-butadiene that is an important industrial chemical used in synthetic rubber production causes a dose-dependent inhibition of deciduoma development in pseudopregnant Sprague-Dawley rats. This study used 4 daily i.p. BDE doses of 0.20, 0.25, 0.30, 0.35, or 0.40 to characterize mechanisms that may be responsible for the antideciduoma effect. Pseudopregnant rats were treated either before (pseudopregnancy [PPG] days 1-4) or after (PPG days 5-9) deciduoma induction by endometrial trauma with a blunt needle. Animals were killed on PPG day 9 and evaluated for serum progesterone and endometrial protein and DNA. RT-PCR was used to measure message for estrogen receptor (ER) alpha and pituitary adenylate cyclase-activating polypeptide (PACAP). Substrate zymography and Western blotting were used respectively to measure matrix metalloproteinase (MMP)-9 and inducible nitric oxide synthase. The antideciduoma effects of BDE were associated with decreases in endometrial weight, protein, and DNA, with decreases in serum progesterone, and with decreases in PACAP message and MMP-9. A reduction in NOS was identified at the highest dose of BDE. Message for estrogen receptor (ER) alpha was not affected at any dose. We conclude that the reduction in decidual proliferation was direct and appeared to be associated with either 1) a decrease in the effectiveness of the deciduogenic stimulation and/or a weakened endometrial sensitivity to the stimulus; or 2) an effect on deciduoma development. Molecular mechanisms that apparently contributed to BDE inhibition of decidual metabolism included the synthesis of protein and DNA involved in decidual growth, the synthesis and activation of a matrix metalloproteinase for degradation of the extracellular matrix that is essential for tissue remodeling during deciduoma development, and the nitric oxide/nitric oxide synthase and pituitary adenylate cyclase-activating peptide systems that are involved in promoting vasodilation and increased vascular permeability to enhance the availability of substrates for maximal deciduoma growth. The ovotoxicity of BDE, which has previously been established, may indirectly affect decidual proliferation by reducing progesterone, the preeminent endocrine regulator of deciduoma development. The findings also suggest that BDE may possess no estrogenic action since it was associated with endometrial weight loss and unaltered levels of the estrogen receptor alpha mRNA expression.

Animals↗