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Biomedical subjects

Z Pan

Publications and source records attributed to Z Pan.

At least 127 records · Page 7Linked to original sources
PubMed1995

Intermittent treatment of prostaglandin E2 with risedronate is more anabolic than prostaglandin E2 alone in the proximal tibial metaphysis of ovariectomized rats.

This study is designed to test how intermittent application of prostaglandin E2 (PGE2) and risedronate (Ris) alone or in combination acts on the cancellous bone mass in estrogen-deficient rats. Sprague-Dawley rats were ovariectomized (ovx) or sham-ovx'd at 6 months of age. PGE2 (6mg/kg/d), Ris (5 micrograms/kg/twice a week) or PGE2 plus Ris were given for 60 days to ovx rats immediately after operation and followed by 60 days without treatment. The drugs were then reapplied for another 60 days. Static histomorphometry was performed on the secondary spongiosa of proximal tibial metaphysis (PTM). Sixty days of ovx lost trabecular bone and number, Ris prevented ovx-induced bone loss. PGE2 added 48% extra cancellous bone, but the new bone was completely lost after 60 days of withdrawal. Another 60 days of PGE2 treatment only partially restored the trabecular bone, the bone mass was still -42% lower than that of sham-ovx controls. Co-treatment of PGE2 with Ris added the same amount of bone as PGE2 alone after the first 60 days treatment period, but differed from PGE2 alone in that the new bone lost less during the 60 days withdrawal period. Re-application of co-treatment for another 60 days added more extra bone. We concluded that intermittent co-treatment with anabolic and anti-resorptive agents is more effective than anabolic agent alone in long-term therapy of cancellous bone in estrogen-deficient rats.

Analysis of Variance↗
PubMed1995

Intermittent treatments of prostaglandin E2 plus risedronate and prostaglandin E2 alone are equally anabolic on tibial shaft of ovariectomized rats.

Effects of intermittent administration of prostaglandin E2 (PGE2), risedronate (Ris) and their combination on bone mass were studied on the cortical bone of tibial shafts of ovariectomized (ovx) rats. Six month old ovx rats were treated immediately after operation with subcutaneous injections of 6 mg PGE2/kg/d, 5 micrograms Ris/kg/2x/wk or their combination for 60 days each of an on/off/on cycle. PGE2 alone and in combination with Ris added the same amount of new bone in the first 60 days on period. During the 60 days off period, newly added endocortical and marrow trabecular bone disappeared in PGE2 alone treatment groups. In co-treatment group, the marrow trabeculae were only partly lost. There was no difference in total bone area between co-treatment and PGE2 alone groups after another 60 days on treatment. Our findings indicate that co-treatment was better in the maintenance of newly added endocortical and marrow trabecular bone during the off period; however, it formed less bone than PGE2 alone during the second treatment period, and ended up with the same amount of bone with both treatments.

Animals↗
PubMed1995

Risedronate plus prostaglandin E2 is superior to prostaglandin E2 alone in maintaining the added bone after withdrawal in a non-growing bone site in ovariectomized rats.

Effects of risedronate and prostaglandin E2 (PGE2) alone or in combination on the distal tibia, a non-growing bone site with closed epiphysis at 3 months of age, were studied in ovariectomized (ovx) rats. Six-month-old Sprague-Dawley female rats were either ovx or sham-ovx. Rats were treated immediately after operation either with risedronate (5 micrograms/kg/2x/wk), PGE2 (6 mg/kg/d), or risedronate+PGE2 for 60 days (on-groups) and followed by 60 days without treatment (off-groups). Trabecular area, width and numbers were determined in metaphyseal cancellous bone of the distal tibia. No significant bone loss or structural changes were observed in the distal tibial metaphysis after 120 days of ovx. Risedronate alone did not produce any effect on bone mass during the treatment and the withdrawal periods. PGE2 alone increased the trabecular bone mass associated with thickened trabeculae and increased trabecular numbers. However, some of the newly formed bone was lost at the end of 60 days withdrawal. Combination of risedronate and PGE2 treatment added the same amount of bone mass as PGE2 alone, and the added new bone was maintained during the 60 days withdrawal. These results indicate that treatment with risedronate and PGE2 can preserve the anabolic effect of PGE2 on bone mass for at least 60 days after treatment.

Analysis of Variance↗
PubMed1995

[Routine use of electronic portal imaging. Positioning verification in 922 successive pelvic fields].

Treatment reproducibility is a major criterion of quality assurance in radiation therapy. During each course, the same dose should be delivered in the same volume of irradiation. Today, portal imaging devices can be used routinely to check and correct patient positioning before much of the daily irradiation has been delivered. In this study we used the Portal Vision Varian (PVV) system during pelvic irradiation in 16 patients. This device can automatically acquire portal images in the first seconds of each course. Observed discrepancies are directly classified by the radiation oncologist according to their type (cranio-caudal, lateral, antero-posterior) and severity (correction of patient positioning is necessary or not). In case of error, patient positioning is corrected before the end of irradiation. Of the 922 portals analysed with PVV, 901 could be analysed (97%). Two hundred and ninety-nine positioning discrepancies were observed (33%) with 59 of them leading to correction (6%). Most of the time, these errors concerned antero-posterior portals. Finally, each patient had an average of 18 to 19 discrepancies which were mainly of no importance for treatment quality. Nevertheless, real errors leading to correction were observed in 14 patients (88%) with an average of four per patient. In some patients many errors occurred, while in others only a few. These shifts were not related to patient weight and thickness but probably a portal dimension. In summary, we think that during pelvic irradiation a portal imaging device should be used daily to improve treatment quality. This system can help the radiation oncologist to discover many positioning errors (an average of four) in the majority of patients (88%) and to correct them before the end of irradiation.

Humans↗
PubMed1995

Immunization with vesicular stomatitis virus nucleocapsid protein induces autoantibodies to the 60 kD Ro ribonucleoprotein particle.

BACKGROUND: Systemic lupus erythematosus (SLE) is an autoimmune disorder of unknown etiology that is characterized by antibodies binding ribonucleoprotein complexes. The epitopes of SLE associated 60 kd Ro (or SSA) autoantigen share sequence with vesicular stomatitis virus (VSV) nucleocapsid (N) protein and SLE patients with anti-Ro are more likely to bind the N-protein than anti-Ro negative patients. METHOD: We immunized New Zealand white (NZW) rabbits with purified VSV N-protein to examine the relationship between the immune response to N-protein and anti-Ro. RESULTS: After multiple immunizations with VSV N-protein, NZW rabbits produced not only IgG antibodies to VSV N-protein but also an autoimmune response to Ro antigen. The IgG fraction of the rabbit immune serum precipitates 60 kd Ro protein as well as its associated Y RNAs. Antibodies elicited by 10 immunizations of VSV N-protein bind to at least 20 linear epitope groups on VSV N-protein and over 25 linear epitope groups on 60 kd Ro protein. These antibodies also bound 5 of the 6 shared sequences between 60 kd Ro protein and VSV N-protein. CONCLUSIONS: Our data demonstrate that an immune response initiated towards a foreign antigen, selected on the basis of sharing short sequence similarity with the autoantigenic epitopes of an autoantigen, can lead to an autoimmune response.

Animals↗
PubMed1994

Neurotrophin regulation of energy homeostasis in the central nervous system.

Our hypothesis is that one cause of neuronal cell death and shrinkage in the aged central nervous system is an inability of neurons to maintain oxidant homeostasis in the face of increased levels of reactive oxygen species, decreased endogenous antioxidants, and impaired energy metabolism associated with physiological senescence, Alzheimer's, and Parkinson's diseases. Since treatment with nerve growth factor (NGF) reverses behavioral impairments in aged rats and stimulates cholinergic activity in the basal forebrain, while brain-derived neurotrophic factor appears to play a similar role in the striatum, we propose that neurotrophin-mediated cell-sparing reflects effects on oxidant homeostasis. Neurotrophins may play a similar cell-sparing role in hypoxic/ischemic injury to the nervous system, which also is mediated in part by reactive oxygen species. The degradation of one such species, H2O2, is catalyzed by catalase and glutathione peroxidase (GSH Px). The activity of the latter enzyme is dependent on glutathione reductase and the availability of NADPH for regeneration of reduced GSH. The GSH redox cycle is also regulated by enzymes of the hexose monophosphate shunt. NGF protects PC12 cells from H2O2 injury by stimulating the synthesis of antioxidant enzymes including catalase, GSH Px, glucose-6-phosphate dehydrogenase, and gamma-glutamylcysteine synthetase, the rate-limiting enzyme for glutathione synthesis. NGF also enhances recovery from the NAD+ losses occurring as a consequence of H2O2 treatment.

Animals↗
PubMed1994

[Several blood group antigens expressions in laryngeal cancer tissue and their clinical significance].

In this study we used the method of immunohistochemistry (ABC method) to examine antigen A, B, H and T expression in laryngeal cancer tissue and their clinical significance. Results showed that disappearance of antigen A, B, H was related to patient's prognosis and cancer cell differentiation. Antigen T revealed powerful expression in patients with cervical lymph node metastases. This index can help diagnosing subclinical metastases of the cervical lymph node.

ABO Blood-Group System↗
PubMed1993

Role of nerve growth factor in oxidant homeostasis: glutathione metabolism.

Free radicals are generated in the CNS by ongoing oxygen metabolism and biological events associated with injury and inflammation. Increased free radical levels may also persist in some chronic neurological diseases and in the aged. Nerve growth factor (NGF) is a member of the neurotrophin family of proteins that can regulate neuronal development, maintenance, and recovery from injury. NGF protected rat pheochromocytoma PC12 cells, an adrenal chromaffin-like NGF-responsive cell line, from the oxidant stress accompanying hydrogen peroxide treatment by stimulating GSH levels and enzymes in the GSH metabolism cycle and in the GSH/GSH peroxidase antioxidant redox system, a ubiquitous cellular antioxidant system. Specifically, NGF increased gamma-glutamylcysteine synthetase (GCS) activity, the rate-limiting enzyme for GSH synthesis, by 50% after 9 h and GSH levels by 100% after 24 h of treatment. NGF stimulated GSH peroxidase by 30% after 3 days and glucose 6-phosphate dehydrogenase by 50% after 2 days. Treatment with NGF and cycloheximide, or actinomycin D, which inhibit protein and RNA synthesis, respectively, blocked the NGF stimulation of GCS and glucose 6-phosphate dehydrogenase. Increased GSH levels due to NGF treatment were responsible for the significant protection of PC12 cells from hydrogen peroxide-induced stress. Pretreatment of PC12 cells with NGF for 24 h rescued cells from the toxic effects of the extracellular hydrogen peroxide generated by the glucose/glucose oxidase system but did not rescue cells that were subjected to GSH deprivation due to treatment with 10 microM L-buthionine-(S,R)-sulfoximine, an inhibitor of GCS.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Production of hybrid bispecific antibody recognizing human colorectal carcinoma and CD3 antigen.

The present study reports on the use of gene transfer by vector DNA in the generation of hybrid hybridoma, the quadroma secreting the hybrid bispecific antibody. A quadroma B72.3neo/OKT3gpt was simply derived from the fusion of two hybridoma cell lines, B72.3 and OKT3, tagged with vector DNA mpSV2neo and mpSV2gpt, respectively, and selected in the media containing both G418 and mycophenolic acid. The hybrid bispecific antibody B72.3/OKT3 was purified from the quadroma ascites by the use of hydroxylapatite column on high-pressure liquid chromatography. This bispecific antibody contained one binding site for the TAG72 antigen on OVCAR3 tumor cells and the other binding site for the CD3 molecule on human T cells. It was able to target human T lymphocytes to significantly lyse the human ovarian cancer cells and may therefore be useful in immunotherapy of cancer.

Antibodies, Monoclonal↗
PubMed1991

[The determination and evaluation of the plasma amino acid in respiratory failure].

The measurement of the plasma amino acid was made in 15 patients with chronic respiratory failure and 15 persons of control. The results showed: (1) The plasma acid model changed. Lysine increases and arginine decreases, due to hypothermia. Hypercapnia imbalance of acid and alkali and changes of hepatic dysfunction etc. (2) The prognosis of respiratory failure as well as its severity was judged according to the decreasing extent of arginine and BCAA. The more worse the condition of the disease, the more lowering of the level of arginine and BCAA. (3) The changes of blood gas analysis and hepatic dysfunction may effect on the metabolism of plasma amino acid in some degree. (4) Hypoxemia in infected patients with respiratory failure may cause peripheral deficit of energy. We suggested that patients should be given BCAA and arginine for more energy as anti-infection and oxygen therapy were used.

Adult↗
PubMed1989

[Effects of stenosis on blood flow in the coronary artery of dogs].

The effects of stenosis on coronary blood flow (CBF) were studied in 22 open-chest mongrel dogs. A progressive stenosis was produced by a micrometer constrictor on the left circumflex coronary artery. Mean aortic pressure (Pa), distal coronary pressure (Pc) and stenotic segment pressure drop (delta P) were measured. Curve of CBF versus % stenosis showed that CBF was relatively constant with stenosis less than 85%, CBF rapidly decreased with stenosis of 85-95%, and then slowly reduced as stenosis was further increased. The change in CBF versus % stenosis was expressed as follows: CBF = 1.48 X 10(10) theta -27.6 A (where A = % stenosis in lumen area). With progressive coronary artery stenosis (greater than 75%), the change in percent stenosis and Pc showed a negative correlation: Pc = 159.1-1.36A (r = -0.73, P less than 0.01); the change in Pc and CBF showed a positive correlation: Pc = 16.9 + 1.3 CBF (r = 0.74, P less than 0.01).

Animals↗