Search PubMed⌕ Search

Biomedical subjects

N Zhang

Publications and source records attributed to N Zhang.

At least 181 records · Page 10Linked to original sources
PubMed1995

Guinea pig serum L-asparaginase: purification, and immunological relationship to liver L-asparaginase and serum L-asparaginases in other mammals.

L-asparaginase, an enzyme used in the treatment of acute lymphocytic leukemia, is found in the serum of only a few mammalian groups, including the guinea pig and its close relatives in the superfamily Cavioidea. This report describes the purification and characterization of L-asparaginase from guinea pig serum. Antiserum against the purified enzyme cross-reacted with sera from other Cavioidean species but not with mouse serum. Relatively weak cross-reaction with unpurified L-asparaginase in guinea pig liver indicates a significant degree of evolutionary divergence.

Animals↗
PubMed1995

The effect of retrograde cerebral perfusion after particulate embolization to the brain.

Neurologic injury as a consequence of cerebral embolism of either air or atherosclerotic debris during cardiac or aortic surgery is still a major cause of postoperative morbidity and mortality. While exploring various means of improving cerebral protection during complex cardiothoracic procedures, we have developed a chronic porcine model to study retrograde cerebral perfusion. We have previously demonstrated that retrograde perfusion results in a small amount of nutritive flow and provides cerebral protection that appears to be superior to simple prolonged hypothermic circulatory arrest. The current study was designed to evaluate the efficacy of retrograde cerebral perfusion in mitigating the effects of particulate cerebral embolism occurring during cardiac surgery. Four groups of pigs (19 to 28 kg) underwent cardiopulmonary bypass with deep hypothermia at an esophageal temperature of 20 degrees C: an antegrade control group (AC, n = 5), an antegrade embolism group (AE, n = 10), a retrograde control group (RC, n = 5), and a retrograde embolism group (RE, n = 10). In addition, because of extreme heterogeneity in outcome in the initial RE group, an additional group of 10 animals underwent embolism and retrograde perfusion at a later time. Embolization was accomplished by injection of 200 mg of polystyrene microspheres (250 to 750 micrograms in diameter) via the aortic cannula into an isolated aortic arch preparation in the AE and RE groups; the control groups received injections of 10 ml of saline solution. After infusion of the microspheres or saline solution, conventional perfusion, with the aortic arch pressure maintained at 50 mm Hg, was continued for a total of 30 minutes in the antegrade groups; in the retrograde groups, retrograde flow was initiated via a cannula positioned in the superior vena cava, and was continued for 25 minutes. Superior vena caval flow was regulated to maintain a sagittal sinus pressure of approximately 30 mm Hg in the retrograde groups, and blood returning to the isolated aortic arch was collected and measured. All animals were allowed to recover and were evaluated daily according to a quantitative behavioral score in which 9 indicates apparently complete normalcy, with lower numbers indicating various degrees of cerebral injury. At the time of planned death on day 6, half of the brain was used for recovery of embolized microspheres after digestion with 10N sodium hydroxide. The other half was submitted for histologic study. Neurologic recovery in both the antegrade and retrograde control groups appeared to be complete, although mild evidence of histologic damage was present in some animals in the retrograde control group.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

HIV type 1 protease activation of NF-kappa B within T lymphoid cells.

NF-kappa B is a nuclear protein of the rel oncogene family capable of enhancing transcription of several cellular genes, including IL-2 and the IL-2 receptor, and viral genes transcribed from the HIV-1 LTR. It has been reported that HIV-1 protease may cleave the NF-kappa B precursor to its active form in vitro. In this study the effects of HIV protease on NF-kappa B precursor activation were examined in Jurkat T cells by introducing a protease expression vector into the cells. Increased NF-kappa B activity was observed and this increased activity was blocked by a specific inhibitor of the viral protease. Viral transcription, as measured using LTR-CAT assays, was only slightly enhanced in the HIV-protease expressing cells, while secretion of IL-2 and expression of the IL-2 receptor were not affected. The limited activation of NF-kappa B by HIV protease appears unlikely to have a significant effect on virus expression or T cell function.

Base Sequence↗
PubMed1995

[Tuberculous lymphadenitis: a sarcoidosis-like variation].

By means of polymerase chain reaction technique to amplify DNA sequence specific for mycobacterium tuberculosis (M. TB-PCR), BCG immunohistochemistry (BCG-IHC) as well as acid fast stain (AF), mycobacterium other than tuberculosis (MOTT) and mycobacterium tuberculosis (M. TB) were detected in paraffin blocks from 12 cases diagnosed by consultant pathologists as lymph node "sarcoidosis". Of the 5 cases which consulting pathologists unanimously agreed to the lymph node "sarcoidosis" diagnosis, 1 case showed BCG-IHC (+) and M. TB-PCR (+); Of the 7 cases which most of the consulting pathologists agreed to be "sarcoidosis", 1 case showed AF (+), BCG-IHC (+) and M. TB-PCR (+). The results suggest: (1) some tuberculous lymphadenitis cases may present as "sarcoidosis"-like lesions; (2) lymph node sarcoidosis may be related to MOTT and M. TB infection.

Adult↗
PubMed1995

[Rheumatic diseases in China].

To determine the prevalence of rheumatic diseases in Chinese of Han nationality in the north and the south of China, samples of 4,192 adults in Beijing (north) and 5,057 in Shantou (south) area were studied. The same questionnaire was administered to each subject surveyed. Physical examinations were done in all who gave positive answers. For those who gave positive response to certain set of questions, blood antinuclear antibody and rheumatoid factor tests and radiographs of hand and/or sacroiliac joint were done. The prevalence of definite rheumatoid arthritis (RA) was 0.34% in the north (95% confidence interval 0.20-0.51) and 0.32% (0.95% CI 0.16-0.47) in the south and ankylosing spondilitis was noted in 0.26% of both samples (95% confidence interval in the north 0.11-0.42 and in the south 0.14-0.40). Only 3 cases of systemic lupus erythematosus in the north and one in the south were identified. General rheumatic pain was reported more frequently in the north. Lumbar problems were recorded on examinations 5 times more commonly in the north than in the south (men 25.0% vs 5.3%, women 38.0% vs 6.5%) and knee problems 10 times (men 24.0% vs 1.8%, women 36.0% vs 3.4%) more commonly in the north; the difference was greatest in the age of 55-64. A further study in the south is planned to assess the contribution of inter-observer error and/or difference in cultural response to the north/south difference observed in the prevalence of general rheumatic symptoms and back pain. A search for environmental risk factors such as climate, diet, degeneration or overuse would then be indicated to explain these differences.

Adult↗
PubMed1995

[An epidemiological study of knee osteoarthritis].

2,063 adult people of a Beijing suburban village were surveyed for osteoarthritis of the knees. Questionnaire was completed in all. 799 (38.7%) responded to have knee joint pain. 311 with knee joint pain and 212 without knee joint pain were selected randomly for X-ray films of the knees. In the former group, 79 showed osteoarthritic X-ray changes and were thus diagnosed as such, accounting 24.7% of those with knee pain. In the latter group, all were not diagnosed as clinical osteoarthritis, yet 54 (25.5%) showed also X-ray osteoarthritic changes. In both groups the X-ray osteoarthritic changes increased in parallel with increase of age, reaching 78% in those aged 60 and more in the former group and 67% in the latter group. 100 retired cadres were similarly surveyed but all had X-ray films of the knees taken. 51 of 100 responded knee pain, out of whom 49 (95.9%) showed X-ray osteoarthritic changes and were thus diagnosed as such. The overall prevalence rate of osteoarthritis of knee in rural population as judged by the 523 who had taken X-ray films (people with and without knee pain are not entirely proportional) is about 9.6% and that of 100 aged retired cadres is 49%. Those with X-ray knee osteoarthritic changes but without knee pain were not categorized as clinical osteoarthritic cases.

Adolescent↗
PubMed1995

[Effect of tripchlorolide (T4) of Tripterygium wilfordii Hook on the production of endothelin-1 by endothelial cells of human umbilical vein].

Tripchlorolide (T4), a single active ingredient of Tripterygium wilfordii Hook was shown to possess both anti-inflammatory and immunosuppressive actions in experimental animals. The paper reports the effect of T4 on the production of endothelin-1 (ET-1) by endothelial cells of human umbilical vein. The cells were incubated with different doses of T4 (2.5, 5, 10 and 20 ng/ml) for 24 hours. By radioimmunoassay the results showed that T4 at concentration of 5 ng/ml significantly inhibited the production of ET-1 by endothelial cell in a dose dependent trend. The significance of T4 action was discussed.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1995

[Experimental steroid osteonecrosis in rabbits and pathologic findings].

Osteonecrosis of femoral head was experimentally induced in adult rabbits by employing a combined protocol of hypersensitive vasculitis and administration of high dose corticosteroids. By using India ink introartery infusion microangiography and pathologic examination, we found that the damage of terminal arterioles and interruption of blood supply of terminal arteriole was causative pathogenesis. In the early phase, the haemopoietic necrosis and enlargement of fat cell in the bone marrow occurred. The perfused arterioles decreased, especially in the subchondrol bone. In the later phase, the osteocytes showed necrotic fibrosis in bone marrow. The perfused arterioles increased gradually and repairtive changes began.

Animals↗
PubMed1995

[The role of endothelin-1 and tumor necrosis factor-alpha in the development of asthma sarcoidosis].

In order to investigate the interaction of endothelin-1 (ET-1) and tumor necrosis factor-alpha (TNF-alpha) and their activity in the pathogenesis of asthma, ET-1 plasma and BALF levels were measured, and the amount of TNF-alpha released from alveolar macrophage (AM) was also tested. As in vitro the airway smooth muscle cells were stimulated with TNF-Alpha, the release of ET-1 was also observed. The results showed that the amount of ET-1, TNF-alpha were both increased than in the control group, at the same time, TNF-alpha could stimulate smooth muscle cells to secrete ET-1. We concluded that the release of ET-1 induced by TNF-alpha might play a certain role in development of airway hyperresponsiveness and airway remodeling.

Animals↗
PubMed1994

Syntenic assignment of human chromosome 1 homologous loci in the bovine.

Three mouse chromosomes (MMU 1, 3, and 4) carry homologs of human chromosome 1 (HSA 1) genes. A similar situation is found in the bovine, where five bovine chromosomes (BTA 2, 3, 5, 16, and unassigned syntenic group U25) contain homologs of HSA 1 loci. To evaluate further the syntenic relationship of HSA 1 homologs in cattle, 10 loci have been physically mapped through segregation analysis in bovine-rodent hybrid somatic cells. These loci, chosen for their location on HSA 1, are antithrombin 3 (AT3), renin (REN), complement component receptor 2 (CR2), phosphofructokinase muscle type (PFKM), Gardner-Rasheed feline sarcoma viral (v-fgr) oncogene homolog (FGR), alpha fucosidase (FUCA1), G-protein beta 1 subunit (GNB1), alpha 1A amylase, (AMY1), the neuroblastoma RAS viral (v-ras) oncogene homolog (NRAS), and alpha skeletal actin (ACTA1). AT3, REN, CR2, and GNB1 mapped to BTA 16, PFKM to BTA 5, AMY1A and NRAS to BTA 3, FGR and FUCA1 to BTA 2, and ACTA1 to BTA 28.

Animals↗
PubMed1994

A genetic linkage map of the bovine genome.

A cattle genetic linkage map was constructed which marks about 90% of the expected length of the cattle genome. Over 200 DNA polymorphisms were genotyped in cattle families which comprise 295 individuals in full sibling pedigrees. One hundred and seventy-one loci were found linked to one other locus. Twenty nine of the 30 chromosome pairs are represented by at least one of the 36 linkage groups. Less than a 50 cM difference was found in the male and female genetic maps. The conserved loci on this map show as many differences in gene order compared to humans as is found between humans and mice. The conservation is consistent with the patterns of karyotypic evolution found in the rodents, primates and artiodactyls. This map will be important for localizing quantitative trait loci and provides a basis for further mapping.

Animals↗
PubMed1994

High efficiency retroviral-mediated gene transduction into CD34+ cells purified from peripheral blood of breast cancer patients primed with chemotherapy and granulocyte-macrophage colony-stimulating factor.

The hematopoietic system has been one of the major targets for designing human gene therapy protocols. In the present system, we have transduced LNL6, one of the most commonly used retroviral vectors in gene therapy, into purified CD34+ cells from peripheral blood of patients primed with chemotherapy and granulocyte-macrophage colony-stimulating factor (GM-CSF). Purification of CD34+ cells was achieved by incubation with a murine anti-CD34 monoclonal antibody (9C5), and subsequently with paramagnetic microspheres (Dynal) coated with sheep anti-mouse IgG1 (Fc). The CD34+ cells were released from the beads by treatment with chymopapain. Flow cytometry analysis using the anti-CD34 antibody HPCA-2-FITC targeted at another epitope of CD34 showed that 78-97.5% of the cells thus purified were CD34+. After retroviral-mediated gene transfer, polymerase chain reaction (PCR) analysis revealed that 67-100% of the hematopoietic colonies contained the marker gene neo, indicating that CD34+ cells purified by immunomagnetic microsphere method from peripheral mononuclear cells primed with hematopoietic growth factors are highly susceptible to retroviral-mediated gene transfer. The expression of neo as determined by reverse transcription (RT)-PCR appeared to be unstable and not persistent. Taken together, our data suggest that LNL6 is a suitable vector for gene marking of hematopoietic progenitors but not for gene therapy protocols based on persistent gene expression.

Antigens, CD↗
PubMed1994

Effect of time of carbohydrate ingestion on muscle glycogen resynthesis after exhaustive exercise in rats.

We studied the optimal time of carbohydrate ingestion required to restore muscle glycogen storage after exhaustive exercise in rats. The animals were divided into 4 groups (IN0, IN30, IN60 and IN120), each receiving 30% glucose solution (30 g/kg body weight) through a stomach tube 0, 30, 60 or 120 minutes after exercise. Six hours after administration of glucose, the glycogen concentration in the m. extensor digitorum longus returned to the baseline in the IN0 group, while reaching only 77%, 80% and 73% of the baseline in the IN30, IN60 and IN120 groups, respectively. There was a significant difference in this variable between the IN0 group and any of the three other groups. On the other hand, the glycogen concentration in the m. soleus returned to the baseline in all groups with no difference. These findings suggest that muscle glycogen may be most efficiently resynthesized if carbohydrate is given immediately after exercise, and that muscle glycogen resynthesis may vary with the type of muscle.

Animals↗
PubMed1994

[Effects of tripchlorolide (T4) of Tripterygium wilfordii Hook on the proliferation of peripheral blood mononuclear cells of rheumatoid arthritis patients].

Tripchlorolide (T4) is a single active ingredient recently isolated from Tripterygium wilfordii Hook. The effects of T4 on the proliferation of peripheral blood mononuclear cells (PBMC) of rheumatoid arthritis (RA) patients and normal subjects were studied, RA patients and sex- and age-matched normal subjects (each 8 cases) were selected. PBMC were incubated with T4 of various doses (10, 20, 30 and 40 ng/ml) in the presence or absence of PHA for 72 hours. The results were as follows: T4 remarkably inhibited the proliferation of both PHA-stimulated and unstimulated PBMC of normal subjects and PHA-stimulated PBMC of RA patients as measured by MTT colormetric method. However, T4 showed a biphasic reaction in unstimulated PBMC of 3 RA patients. These results indicates that T4 would be useful in the therapy of RA. The significance of biphasic reaction occurring in RA patients needs to be further investigated.

Adult↗