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Biomedical subjects

N Zhang

Publications and source records attributed to N Zhang.

At least 217 records · Page 12Linked to original sources
PubMed1992

Wheat vegetative nitrogen compositional changes in response to reduced reproductive sink strength.

N redistribution patterns and the N composition of vegetative tissues above the peduncle node of wheat (Triticum aestivum L.) plants with altered reproductive sink strength were evaluated to determine the role of vegetative storage proteins in the temporary storage of excess N destined for export. The degree of leaf senescence symptoms (loss of chlorophyll, total N, and ribulose-1,5-bisphosphate carboxylase/oxygenase) were initially reduced, but the complete senescence of vegetative tissues proceeded even for plants completely lacking reproductive sinks. Plants with 50% less sink strength than control plants with intact spikes redistributed vegetative N to the spike almost as effectively as the control plants. Plants without reproductive sinks exported less N from the flag leaf and had flag leaf blades and peduncle tissues with higher soluble protein and alpha-NH(2) amino acid levels than control plants. An abundant accumulation of polypeptides in the soluble protein profiles of vegetative tissues was not evident in plants with reduced sink strength. Storage of amino acids apparently accommodates any excess N accumulated by vegetative tissues during tissue reproductive growth. Any significant role of vegetative storage proteins in the N economy of wheat is unlikely.

Journal Article↗
PubMed1992

Angiotensin II receptors in the solitary-vagal area of hypertensive rats.

Angiotensin II (Ang II) has been proposed to be an endogenous neuromodulator of the baroreceptor reflex at the level of the brain stem solitary-vagal area. Elevated activity of the brain Ang II system has been implicated in the development and maintenance of hypertension in spontaneously hypertensive rats and deoxycorticosterone acetate-salt hypertensive rats. In the present study, we sought to determine if Ang II receptors in the solitary-vagal area exhibited altered binding kinetics in spontaneously hypertensive rats or deoxycorticosterone-salt hypertensive rats. Ang II receptors were examined by quantitative autoradiographic analysis of iodine-125-labeled [Sar1,Ile8]Ang II binding in the solitary-vagal area in six groups of animals: 1) spontaneously hypertensive rats, 2) normotensive Wistar-Kyoto rats, 3) uninephrectomized rats, 4) uninephrectomized rats with a 1% solution of saline for drinking water, 5) uninephrectomized and deoxycorticosterone-treated rats, and 6) uninephrectomized and deoxycorticosterone-treated rats given a 1% solution of saline for drinking water. Blood pressure was significantly elevated in the spontaneously hypertensive rats and deoxycorticosterone-salt rats relative to control animals. There was a significant decrease in the binding affinity (increased KD) for 125I-[Sar1,Ile8]Ang II and a significant increase in the maximum binding density for 125I-[Sar1,Ile8]Ang II in the solitary-vagal area of spontaneously hypertensive rats relative to Wistar-Kyoto rats. Deoxycorticosterone-salt rats also exhibited significantly higher KD and maximum binding density values compared with controls. These results indicate that Ang II receptor binding is altered in the solitary-vagal area of two different models of experimental hypertension and suggest that these changes could contribute to the expression of the hypertensive state.

Angiotensin II↗
PubMed1992

Genomic organization of the putative human homeobox proto-oncogene HOX-11 (TCL-3) and its endogenous expression in T cells.

The HOX-11 (TCL-3) gene, which is abnormally expressed in the leukemic cells of some patients with T-cell acute lymphoblastic leukemia, is a new member of the homeobox gene family. It is structurally altered by the t(10;14) chromosomal translocation, resulting in head-to-tail juxtaposition of HOX-11 with the T-cell receptor delta-chain gene. In order to understand the normal functions of HOX-11 and its role in T-cell leukemia, we have determined the exon-intron structure of the HOX-11 gene. By using oligonucleotide primers flanking an intron of the HOX-11 gene, we have developed a quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay for the expression of HOX-11. We detected HOX-11 expression in multiple cell lineages including normal T cells and two T-cell lines in which the HOX-11 gene appeared to be unaltered in structure. Our results suggest that deregulation of the endogenous expression of HOX-11 in normal T cells represents an essential step towards the formation of this type of T-cell leukemia.

Amino Acid Sequence↗
PubMed1991

Anti-PPD antibodies in Chinese Behçet's disease.

Anti-PPD antibody determinations were carried out by the ELISA method using extracted PPD of tubercle bacillus H37RV as the target antigen. The positive rates of anti-PPD antibodies in patients with active tuberculosis, inactive tuberculosis, Behçet's disease, or non-tubercular disease and in a village population were 97.5%, 77.4%, 48.9%, 33.6% and 13.9%, respectively. Although the average titer of anti-PPD antibodies in Behçet's disease was lower (2.168 +/- 0.854) than that in active tuberculosis (3.126 +/- 1.182), it was about the same as that in inactive tuberculosis (2.336 +/- 1.250). In comparison with the village community population surveyed, the average titer of anti-PPD antibodies in Behçet's disease patients was distinctly higher (P less than 0.001). These results indicate that tuberculosis may be etiologically related to Behçet's disease.

Antibodies, Bacterial↗
PubMed1991

[The role of nucleus tractus solitarii (NTS) in acupuncture inhibition of visceral-somatic reflex (VSR)].

Experiments were carried out on 164 rabbits. The transmission of abdominal vagal impulses and the mechanism of inhibitory effect by acupuncture systematically were investigated. 1) Electrical stimulation (single pulse of 20 V, 0.5 ms) of abdominal vagus nerve (AVN) produced two kinds of potential on cervical vagus nerve: the fast wave (10.4-24.4 M/sec) and the slow wave (0.9-1.7 M/sec), the later was more stable. 2) In dorsal medulla oblongata the 'M' shaped evoked potentials with long duration (100 ms or so) were recorded. The results suggest that afferents from AVN are mainly transmitted through the small fibres and multi-synaptic connections in Medulla. 3) Out of 301 response units, 281 units (93.6%) concentrated in NTS and adjacent regions. This result was also confirmed by injection of Horseradish Peroxidase (HRP) in the trunk of AVN. 4) On 24 awake rabbits the VSR were elicited by strong stimulation of AVN. Electroacupuncture (EA) on "Zusanli" points inhibited VSR, an effect lasted over 20 min. This inhibitory effect of EA was reversed partly by Naloxone (0.5 mg/kg iv) and was attenuated after lesion (DC 0.5 mA, 1 min.) of NTS. In conclusion, NTS plays an important role in suppression of VSR by EA (P less than 0.01).

Abdominal Pain↗
PubMed1991

[Management of postoperative arrhythmia after open heart surgery in complex congenital heart disease].

The incidence of postoperative arrhythmia was 35.2% in 264 cases with complex congenital heart diseases underwent open heart surgery between Feb, 1988 and Aug, 1989. Postoperative arrhythmia was closely related to preoperative hematocrit, cardiomegaly, prolonged aortic occlusion, ratio of RV/LV systolic pressure greater than 0.75, hypokalemia and low cardiac output syndrome. Infusion of colloid solution and both potassium and magnesium as well as successful surgery and the preventive administration of antiarrhythmic agent played an important role in the prevention and treatment of postoperative arrhythmia.

Adolescent↗
PubMed1990

Suramin prevents binding of interleukin 2 to its cell surface receptor: a possible mechanism for immunosuppression.

Suramin, a polysulfonic naphthalene antihelminthic drug, inhibits proliferation of a variety of T-cell lines in vitro and induces immunosuppression in some human patients and thymic atrophy and splenic depletion in mice. Recent clinical trials indicate that suramin has activity against human tumors, indicating that it will be necessary to understand the mechanism by which suramin induces immunosuppression. The T-cell growth factor, interleukin 2 (IL2), is the major growth factor involved in regulating lymphoid differentiation and proliferation and thus regulates, to a major degree, the magnitude and duration of the immune response. We demonstrate herein that suramin induces a concentration-dependent decrease in binding of 125I-labeled IL2 to its receptor complex on human and murine T-lymphocytes. Binding of 125I-labeled IL2 to both Mr 75,000 and 55,000 IL2 binding molecules was inhibited by suramin. Similar concentrations of suramin were required to inhibit binding of 125I-labeled IL2, IL2-induced tyrosine phosphorylation, and IL2-induced proliferation, suggesting that these processes may be linked. With murine cells, suramin-induced growth inhibition could be overcome completely by increasing the concentration of IL2, suggesting that suramin inhibited growth by competing for the IL2 receptor. With human cells, growth inhibition by suramin could only be partially overcome by increasing the concentration of IL2, suggesting that an additional growth-inhibiting mechanism is present. The ability of suramin to prevent binding of IL2 to its receptor was used to confirm that prolonged interaction of IL2 with its receptor is required to induce cell proliferation. Since IL2 plays a role in lymphocyte proliferation and differentiation, the ability of suramin to inhibit binding of IL2 to its receptor may explain, in part, the in vivo immunosuppressive activities of suramin.

Animals↗
PubMed1990

Distribution of glutamate-like immunoreactivity in excitatory hippocampal pathways: a semiquantitative electron microscopic study in rats.

A semiquantitative electron microscopic immunocytochemical procedure was used to study the cellular and subcellular distribution of glutaraldehyde-fixed glutamate in rat hippocampal formation. Ultrathin plastic-embedded sections were incubated with a primary glutamate antiserum followed by a secondary antibody coupled to colloidal gold particles. A computer-assisted assessment of gold particle densities revealed that the axon terminals of all of the main excitatory pathways in the hippocampus were enriched with glutamate-like immunoreactivity relative to other tissue elements, including the parent cell bodies (granule and pyramidal cells). The different excitatory pathways showed slightly different labelling intensities: boutons in the termination zone of the lateral perforant path were covered by higher gold particle densities than boutons situated in the termination zones of the medial perforant path, the Schaffer collateral/commissural pathway and the hilar associational/commissural pathway. The mossy fibre terminals were significantly less enriched in immunoreactivity than terminals of the lateral perforant path and the Schaffer collateral/commissural pathway. Within the terminals, glutamate-like immunoreactivity was concentrated over synaptic vesicles and mitochondria. Terminals establishing symmetric junctions with cell bodies or dendritic stems displayed low particle densities, as did glial cell processes. These findings support the idea that glutamate is a major excitatory neurotransmitter in hippocampal excitatory synapses. Our observations are also in line with biochemical data pointing to the existence of a considerable neuronal and a smaller glial, metabolic pool of glutamate.

Animals↗
PubMed1990

Aspartate-like and glutamate-like immunoreactivities in the inferior olive and climbing fibre system: a light microscopic and semiquantitative electron microscopic study in rat and baboon (Papio anubis).

A post-embedding immunogold procedure was used to analyse, in a semiquantitative manner, the distributions of aspartate-like and glutamate-like immunoreactivities in the inferior olive and climbing fibre system in rats and baboons. The neurons in the inferior olive were uniformly labelled for aspartate as well as glutamate, indicating a 100% co-localization of these two amino acids in the cell bodies. The level of glutamate-like immunoreactivity in the climbing fibre terminals was similar to that in the parent cell bodies, as judged by a computer-assisted calculation of gold particle densities. In contrast, the level of aspartate-like immunoreactivity in the climbing fibre terminals was only one-seventh of that of the olivary neurons. No differences were found between the hemispheres and vermis. Nerve terminals in the inferior olive were generally moderately labelled with the aspartate antiserum, as were cell bodies of astrocytes. With a few exceptions, the results obtained in baboons were similar to those in rats. Notably, no evidence was found of an enrichment of aspartate-like immunoreactivity in climbing fibres. The present results do not support previous data suggesting that aspartate is the transmitter of the climbing fibres but indicate that glutamate or another excitatory compound should be considered as candidate for this role. Our findings show that the presence of aspartate-like immunoreactivity in cell bodies is an unreliable indicator of transmitter identity.

Afferent Pathways↗
PubMed1990

[The change of ACh metabolism in the dorsal horn of spinal cord and spinal ganglia during electroacupuncture analgesia (EAA)].

In this paper a preliminary study was made about the relationship between ACh and the primary input of acupuncture sensation based on the changes of content of ACh, its synthetic enzyme (choline acetylase, or ChAC) and its degradation enzyme (acetylcholinesterase, or AChE) in the dorsal horn of the spinal cord and spinal ganglia. The results were found that: 1) EA at "huantiao" exerted a marked analgesia effect, the acupuncture analgesia was inhibited when the lateral dorsal root was cut off. 2) The content of ACh of the EA group were slightly lower than those of the control group. 3) AChE activity in the spinal ganglia and the dorsal horn increased markedly under electroacupuncture stimulation. 4) The activity of ChAC in the dorsal horn of rats under acupuncture stimulation was significantly higher than those of the control group. 5) ACh content in the spinal ganglia increased obviously when the degradation of peripheral ACh was inhibited by prostigmine. 6) With the lumber dorsal roots excised, AChE activity of the operative side were much lower than those of the intact side during EA stimulation. It suggest that the metabolism of ACh in the dorsal horn of the spinal cord and spinal ganglia change during the course of EAA, and only when signals produced at the acupoints are delivered to the spinal cord via ACh-containing primary somatosensory nerves, can they exert analgesic and therapeutic effect of acupuncture.

Acetylcholine↗
PubMed1990

[Sampling survey of mentally deficient people in Sichuan].

From first April to 15th May 1987, 145,201 people were investigated by using the ways of layer, equal probability and mass sampling. Two thousand three hundred and forty two of them were confirmed to be mentally deficient. The incidence was 16.13%. It was estimated that 1,665,000 people have mental deficiency in Sichuan. The estimated range of reliability of 95% was 1,528,000-1,801,000. One million and three hundred ninety three thousand of them only had mental deficiency, while 272,000 had other organic deficiency. Male:female ratio was 101.4:100. The incidence of 6-14 year-old was 38.14%, which was 3 times higher than that of other age groups. Mild mental deficiency was 16.4 times more than severe mental deficiency. The most common causes were hereditary diseases, encephalitis, malnutrition, cerebral trauma, pregnant diseases, etc. All of the causes belonged to preventable diseases.

Adolescent↗
PubMed1990

[Vimentin and tumor diagnosis].

Vimentin was isolated and purified from the pig eye lens by homogenization, ultracentrifugation, extraction in urea buffer and preparative electrophoresis. It was identified with SDS-PAGE and rabbit anti-vimentin was raised against the purified vimentin. The specificity of anti-vimentin was examined with immunohistochemical technique and double immune diffusion. Results showed that the vimentin antibody possessed good specificity for mesenchyme-derived cells. Tumor tissue sections from 151 cases were stained with anti-vimentin, anti-keratin, anti-desmin, anti-S-100 protein, anti-Factor-FVIII released antigen, and anti-lysozyme. Positive staining was obtained in mesenchyme-derived cells, while the epithelial tumor cells did not react with anti-vimentin. It indicated that vimentin antibody is effective for tumor differential diagnosis in surgical pathology.

Diagnosis, Differential↗
PubMed1990

[Treatment of rheumatoid arthritis with low doses of multi-glycosides of Tripterygium wilfordii].

Thirty two cases of rheumatoid arthritis were treated with multi-glycosides of Tripterygium wilfordii (T2) in a dosage of 30 mg daily for 12 weeks. Significant improvements in clinical and laboratory variables were observed. In comparison with the results of routine dose of T2 (60 mg per day) treatment, there was no significant difference to be seen between the two treatment plans. Meanwhile, symptom of rash and slightly alimentary canal lower incidences and milder manifestations of side effects of T2 were found in the patients of low dose group than in that of routine dose group. It is suggested that it is reasonable to choose the dose of 30 mg daily as the routine treatment for rheumatoid arthritis patients.

Adult↗