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Biomedical subjects

C Zhang

Publications and source records attributed to C Zhang.

At least 775 records · Page 43Linked to original sources
PubMed1985

Changes in myocardial oxygen demand and instantaneous ventricular vascular volume during prolonged cross-clamping and reperfusion of the abdominal aorta.

In 47 animals (rats, rabbits) the cardiac side effects of prolonged (3 to 6 hours) abdominal aortic cross-clamping and unclamping (3 to 6 hours) were investigated. The relative instantaneous ventricular vascular volume (IVVV), a factor reflecting myocardial blood supply and the rate pressure product (RPP) representing myocardial oxygen demand were used as parameters. Following cross-clamping the IVVV showed an initial decrease while the myocardial oxygen demand revealed a sudden increase. After unclamping, the myocardial oxygen demand decreased and IVVV improved. Minimal levels of both IVVV and RPP occurred at 6 hours following unclamping. This may be an effect of a myocardial inhibiting substance, released by ischemia and necrosis of the lower extremity.

Animals↗
PubMed1983

The results of radiation therapy in advanced carcinoma of the lung in the Beijing region of China.

From 1958 to 1973, 682 patients with lung cancer were treated by radiation therapy in the Cancer Institute, Chinese Academy of Medical Sciences, Beijing, China. The clinical presentation, sex, age, histology and stage and palliative effects of radiation therapy were reported. The 1-, 3- and 5-year survival rates were 40.62, 8.94 and 3.81%, respectively. The prognostic factors such as staging, histology, combination with chemotherapy and response of tumours are discussed. The causes of failure are also analysed. It is suggested that improving the local control rate of squamous cell carcinoma would increase the survival rate.

Adenocarcinoma↗
PubMedDate not supplied

Constitutive Alzheimer's-type tau epitopes in a neuritogenic rat CNS cell line.

Paired helical filaments (PHFs) of Alzheimer's disease (AD) largely comprise hyperphosphorylated forms of the cytoskeletal protein tau. AD-type tau phosphoepitopes, detected by various monoclonal antibodies, are absent from normal adult neurons, but recent studies have shown that their expression may contribute to neuritogenesis and axon differentiation in the developing nervous system. Therefore, we have examined a brain nerve cell line that is spontaneously neuritogenic for possible expression of AD-type tau epitopes. The neuritogenic rat brain cell line B103 was found to constitutively produce two-AD related epitopes of tau, detected by cellular immunofluorescence studies with the PHF-1 and Alz-50 monoclonal antibodies. Biochemical studies showed that the antibodies bound to proteins within the molecular, weight range expected for phosphorylated tau isoforms. Further verification was established by use of tau antisense oligomers, which eliminated cellular immunofluorescence due to the AD-related monoclonals and polyclonal anti-tau but did not eliminate fluorescence due to anti-tubulin. Cells treated with tau antisense were not neurite-free. Neurites that remained, however, were abnormal, generally short and wavy in appearance. Cellular distribution of the tau epitopes was found to be particularly interesting. Alz-50 recognized only cytoplasmic tau whereas PHF-1 recognized nuclear tau as well as cytoplasmic. Thus, the two epitopes, are morphologically segregated within the cell. Because subcellular segregation of tau is compromised in Alzheimer's disease, mechanisms that segregate AD-type phosphotau epitopes in B103 cells may have relevance to this neurodegenerative disorder.

Alzheimer Disease↗
PubMedDate not supplied

Vitamin D receptor and nuclear receptor coactivators: crucial interactions in vitamin D-mediated transcription.

The nuclear actions of 1,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)] are mediated by the vitamin D receptor (VDR). Binding of ligand induces conformational changes in the VDR which promote heterodimerization with retinoid X receptor (RXR) and recruitment of a number of nuclear receptor coactivator proteins including the steroid receptor coactivator (SRC) family members, select SMAD proteins, a novel coactivator complex referred to as DRIP, and a variety of other putative factors. We recently described a novel nuclear receptor coactivator termed NCoA-62 that interacts with the VDR to enhance 1alpha,25(OH)(2)D(3)-activated transcription. NCoA-62 is unrelated to the SRC family, the DRIP complex, as well as other nuclear receptor coactivators described thus far. The molecular mechanisms involved in NCoA-62 coactivator function are poorly understood, but protein-protein interactions are likely to play an important role. The purpose of this paper is to briefly review salient features of the coactivators involved in VDR-activated transcription and to focus on our current understanding of NCoA-62 and its interplay with other nuclear receptor coactivator proteins. It is clear from the studies described here that a concerted series of interactions with multiple coactivator proteins are essential for high order transactivation by 1alpha,25(OH)(2)D(3) and the VDR.

Animals↗
PubMedDate not supplied

Mitochondrial DNA deletions parallel age-linked decline in rat sensory nerve function.

In rats, the function of sensory nerves in the hind limb declines significantly with age. Normally aging rats and rats treated neonatally with capsaicin were studied here. Quantification of vascular response and substance P in young (3 months) and old (24 months) rats showed additive effects of age and capsaicin treatment. The levels in dorsal root ganglion of a particular deletion in mitochondrial DNA (mtDNA(4834)) were about 300-fold higher in old compared to young rats. Capsaicin treatment had no significant effect on mtDNA(4834) abundance. Dorsal root ganglia of old (but not young) rats were found to contain a spectrum of multiple deletions. The abundance of mtDNA(4834) in dorsal root ganglia from individual rats correlated strongly with their decline in vascular function, even where vascular responses were systematically depressed due to prior capsaicin treatment. One possibility is that mitochondrial DNA mutations directly lead to functional decline at mitochondrial and tissue levels. Alternatively, loss of mitochondrial DNA integrity and physiological decline may be consequences of the same factor, such as oxidative stress.

Aging↗
PubMedDate not supplied

The organization of human leucocyte antigen class I epitopes in HIV genome products: implications for HIV evolution and vaccine design.

Knowledge of human leucocyte antigen (HLA) peptide binding motifs permits rapid selection of candidate viral protein fragments for induction of T cell-mediated immunity. A search for HLA class I peptide binding motifs in structural proteins of human immunodeficiency virus (HIV) of different genetic lineages provides a map of the genetic organization of potential T cell antigenic sites, and at the same time identifies all motifs in highly conserved regions of HIV-1 env, gag and pol. The density of motifs is anomalous at both the high and low end of the spectrum: local organization is characterized by clustering in relatively short regions, while large scale organization is characterized by anomalously long runs between motifs. The former is expected simply due to the fact that motifs often have overlapping anchor residue sets. A detailed statistical analysis of the latter, however, shows that the length of the runs cannot be accounted for by chance alone. Although motif clusters show no preference to be in either conserved or variable regions, low motif density stretches occur preferentially in variable portions of the protein sequence, which suggests that the virus may be mutating to evade the cellular arm of the immune system.

AIDS Vaccines↗