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Biomedical subjects

S Lin

Publications and source records attributed to S Lin.

At least 379 records · Page 21Linked to original sources
PubMed1997

[Changes of 5-HT2A receptor binding on platelet of patients with CAD and the effects of exercise test].

It is known both 5-HT2A receptors of platelet and vascular smooth muscle regulate vascular constriction and platelet aggregation to 5-HT challenge. And that 5-HT-induced hypperreactivity of vascular smooth muscle and platelet were noted in patients with coronary artery disease (CAD). In order to investigate the mechanism of platelet hyperreactivity in cardiovascular disease. Platelet 5-HT2A receptor were measured by specific binding of 3H-ketanserin in patients with CAD (CAD group) and patients with chest pain but without CAD as well as healthy subjects (control group) before and after submaximal treadmill exercise. At the same time the levels of plasma 5-HT were also measured. The results showed: (1) In the resting state, 3H-ketanserin exhibited saturable binding with Bmax of 71.1 +/- 10.1 fmol/mg protein, Kd 1.35 +/- 0.20 nmol/L in control group (n = 8) and with Bmax of 102.1 +/- 22.2 fmol/mg protein, Kd 2.44 +/- 0.66 nmol/L in CAD group (n = 10). Between two groups had no significant difference (P > 0.05). And the specific binding of 2.0 nmol/L 3H-ketanserin and the level of plasma 5-HT in CAD group were higher than those in control group (P < 0.05). (2) After exercise all of the specific binding of 2.0 nmol/L 3H-ketanserin, Bmax of receptor binding and the level of plasma 5-HT were significantly increased in CAD group but not in control group. The above results suggested that the up-regulation of platelet 5-HT2A receptor was involved in the platelet hyperreactivity in CAD. The submaximal treadmill exercise had no significant effect on platelet function in control group, but it could lead to platelet 5-HT2A receptor increment and platelet activation in CAD group. Therefore, these changes of platelet might play a role in the acute myocardial ischemia induced by exercise.

Adult↗
PubMed1997

[The comparison of conventional open cholecystectomy, laparoscopic cholecystectomy and minor-incision cholecystectomy].

To study the clinical value of minor incision for cholecystectomy, compared conventional open cholecystectomy (300 patients, group A), alparoscopic cholecytectomy (300 patients, group B), and minor-incision cholecystectomy (300 patients, group C) with regard to duration (day) of operation, amount of intraoperative bleeding, complications, time (day) of gastrointestinal function recovery, intravenous infusion, and expense and time (day) of hospitalization. The results showed that the operating time, amount of bleeding, duration of intravenous infusion, time of gastrointestinal function recovery and hospitalization in group A were significantly different from those in group B and C (P < 0.05), but the incidence in group A was lower than that in group B. The operating time, amount of intraoperative bleeding, and the time of gastrointestinal function recovery and intravenous infusion in group B were similar to those in group C, but there was a high rate of intraoperative and postoperative complication in group B (1.66%). There was no complication in group C (P < 0.05). Comparison of the effects among group A, B and C showed that it was superior in group C to those in group A and B.

Adolescent↗
PubMed1997

[Detection of antigen specificities of HLA-A, B loci in perennial allergic rhinitis].

In order to elucidate whether there are any features of HLA haplotype in perennial allergic rhinitis and the essentials of its genetic background, the antigen specificities of HLA-A, B loci in 31 non-kindred adult cases of southern Chinese of Han nationality were detected and calculated the antigen frequency, gene frequency and relative risk value of different alleles evaluated by serological methods. The results were compared with 78 healthy adult individuals of Guizhou Han (control group) and revealed that RR (relative risk) of HLA-B27 was as high as 8.25, RR of A31 (2.68), A28 (2.57), B12 (2.57) and A33 (2.27) were also higher than the control group. It is suggested that the presence of the above mentioned antigens are positively associated with the genetic liability of the patients. The RR of A9, B60, A24, B22, B51, B15, B16, B48, B46, B7, A11 and A2 were all lower than 1 representing the genetic stability to allergic rhinitis. The antigen frequency of B27 and A9 were significantly different from that of the control group.

Adolescent↗
PubMed1997

[The development of a CPU controlled COPD recovery training ventilator].

A COPD recovery training ventilator controlled by micro-computer is described. The paper include the design principles of emphasizing on the expiration help and reducing the FRC, stimulating phrenic nerve to strengthen inspiration and to lay up strength, stimulating abdominal muscle or pressing on abdomen to enhance expiration and make diaphragm relaxing thoroughly, four period synchronizing control mode and the hard and soft construction.

Animals↗
PubMed1997

[Measurement and evaluation of radiation dose distribution of gamma-ray altimeter in static test for recovery capsule during simulated landing].

The gamma-ray altimeter, containing a gamma-radioactive source 137Cs with activity of 2.96 x 10(10) Bq, was used to detect the height of the spacecraft recovery capsule during landing. To measure the gamma-dose distribution near to the guidance section, especially at position where the useful load is located in recovery capsule, gamma-dose field at the test-site for one machine test was measured by means of a gamma-dose rate meter FJ-317C and a gamma-dose meter ANRI-01-02. The result showed that the absorbed dose rate at 5 meters from gamma-source on the ground is as low as the radiation protection limit when the altimeter is down to 0.16 m from the ground. The ground reflection effect for gamma-ray decreases as height of the recovery capsule increases. Therefore, the gamma-dose level at useful load in the recovery capsule will meet the requirements of flight safety.

Altitude↗
PubMed1997

[Improvement of product technology on prepared soypean].

This paper reports the new prepared method of Prepared Soypean by purebred culture of Aspergillus niger. The technology condition is that temperture is 28 +/- 2 degrees C and comparative humidity is 95%, time of fermented culture is 15-20 days. After improvement, polluttion of other bacteria is easily avoided.

Aspergillus niger↗
PubMed1997

gamma-Glutamyl hydrolase and folylpolyglutamate synthetase activities predict polyglutamylation of methotrexate in acute leukemias.

Decreased methotrexate (MTX) long-chain polyglutamate formation is associated with MTX resistance whereas high levels of MTX polyglutamate accumulation are found in the blasts of leukemia patients who respond to therapy and have improved outcome. The steady-state level of long-chain MTX polyglutamates depends on the balance of activities of two enzymes: folylpolyglutamate synthetase (FPGS), which adds glutamates to MTX in a gamma-carboxyl linkage, and gamma-glutamyl hydrolase (GGH) or conjugase, which sequentially removes the terminal glutamate residue of MTX polyglutamates. FPGS and GGH activities as well as the formation of total and long-chain MTX polyglutamates were measured after incubation with [3H]MTX in 15 blast samples from patients with acute leukemias (myeloid and lymphoid). The ratio between GGH and FPGS activities was better at predicting the amount of polyglutamate accumulated in the 24-h [3H]MTX assay compared to the determination of either activity alone. The linear regression curve relating the relative levels of long-chain polyglutamates/total polyglutamates with the ratio of GGH/FPGS showed an r value of 0.81 (P < 0.001). These data suggest that the evaluation of both these enzymes at diagnosis may be used as a predictor of MTX polyglutamylation and therefore for response to MTX therapy and outcome.

Acute Disease↗
PubMed1997

The effects of low pH and CO2 on bovine corneal lactate production.

PURPOSE: Hypoxic corneal swelling in human subjects is reduced by CO2 induced corneal acidosis. We investigated whether this effect could be explained by a reduction in lactate production under acidic conditions. METHODS: Lactate production from isolated bovine corneas was assayed under normoxic and hypoxic conditions at normal pH (7.5) and low pH (7.05). Low pH was achieved using a CO2/HCO3- Ringer or a HEPES buffered Ringer. RESULTS: Normoxic corneas produced significantly less (approximately 25%) lactate under all acidic conditions. In contrast, hypoxic corneas produced the same or slightly less lactate under acidic conditions (weighted average of all conditions = 6% less lactate). CONCLUSIONS: From these results, we concluded that pH can have a substantial effect on lactate production, but its influence on glycolytic activity during hypoxia is suppressed and may be negligible.

Acidosis↗
PubMed1997

The biochemical status of the DNA synthesome can distinguish between permanent and temporary cell growth arrest.

We previously identified and characterized the human leukemia (HL-60) cell DNA synthetic machinery as a multiprotein form of DNA polymerase, which was designated the DNA synthesome. This multiprotein replication complex contains DNA polymerases alpha and delta, primase, replication factor C, replication protein A, helicase, poly(ADPribose) polymerase, proliferating cell nuclear antigen, DNA ligase I, and topoisomerases I and II. Recently, the HeLa cell-derived DNA synthesome was identified as a discrete high molecular weight protein band in native polyacrylamide gels. Here, we report our findings regarding the change in the organizational status of the DNA synthesome when HL-60 cells undergo either terminal differentiation or temporary G1 growth arrest. We observed that the HL-60 cell DNA synthesome also migrates as a discrete high molecular weight protein band in nondenaturing polyacrylamide gels. This high molecular weight protein band was present in nuclei derived from both actively cycling cells and aphidicolin-arrested cells but was absent in TPA-induced terminally differentiated cells. We also found that DNA polymerase delta, replication factor C, and proliferating cell nuclear antigen are absent in cells that are induced to differentiate in response to 12-O-tetradecanoyl phorbol-13-acetate treatment but are present in actively cycling cells. The level of replication protein A in differentiated cells was similar to that of cycling cells, whereas the level of annexin I, a cytoskeleton protein, is higher in differentiated cells than it is in actively cycling cells. We conclude that the DNA synthesome remains integrated and inactive in temporarily growth-arrested cells but is disassembled in differentiated cells. Furthermore, we conclude that disassembly of the organized replication complex is a specific cellular event in the process of permanent cell cycle exit and that the process leading to disassembly may be regulated, in part, at the level of gene transcription.

Aphidicolin↗
PubMed1997

Existence of an abnormal nitric oxide metabolism seen in glomeruli and inner medullary collecting duct in diabetic rat.

OBJECTIVE: To investigate the nitric oxide (NO)-dependent 3', 5'-cyclic guanosine monophosphate (cGMP) stimulation or inhibition in isolated glomeruli and inner medullary collecting duct (IMCD) cells from normal and diabetic rats for elucidating the probable role of NO in diabetic nephropathy. METHODS: Glomeruli and IMCD cells were obtained from anesthetized diabetic rats, 2 weeks after streptozotocin-induction, and normal rats, and incubated for 10 minutes under basal state or adding different drugs. cGMP was measured by radioimmunoassay. RESULTS: Diabetic glomeruli had a higher generation of cGMP under basal state but failed to further response of L-arginine, which was contrary to the glomeruli from normal rats. NG-monomethyl-L-arginine prevented the elevation of cGMP after L-arginine stimulation in normal rats but not in diabetic rats. Acetylcholine produced a concentration-dependent of cGMP accumulation in the glomeruli of both groups, but the extent was relatively smaller in diabetic than in normal. A similar tendency was also observed in sodium nitroprusside treated glomeruli. However the cGMP increment in response to atrial natriuretic peptide was identical in the two groups. For the IMCD cells, neither the difference of basal cGMP nor those responses related to acetylcholine or sodium nitroprusside could be observed. But the attenuated response to L-arginine also existed in diabetic IMCD cells. CONCLUSION: Both diabetic glomeruli and IMCD cells have an abnormal NO metabolism, which may account in part for the disturbance of renal hemodynamics.

Animals↗
PubMed1997

[Endometrial cytology in normal postmenopausal women and during hormone replacement therapy].

OBJECTIVE: To explore the possibility of endometrial cyopathologic examination as a method of monitoring endometrium during hormone replacement therapy (HRT) in postmenopausal women. METHODS: Endometrial cells were taken via tubal aspiration in 60 normal postmenopausal women (non-HRT group) and 41 with HRT for 3-18 months (HRT group). Their morphologic changes were observed and compared by cytopathologist. RESULTS: Atrophic endometrium was found in 51.7% of the non-HRT group. Its proportion increased with age and the time after menopause. Macrophages were seen in 68.3% of this group. However, in the HRT group the occurrence of atrophic type and macrophage (12.2%, 7.0% respectively) was significantly lower than that in the non HRT group (P < 0.05). Heterogeneity of endometrial cell type was shown both in non-HRT (38.3%) and HRT (65.8%) groups. CONCLUSIONS: Endometrial cells of postmenopausal women are not always atrophic in appearance. They change significantly during HRT. Endometrial cytological examination may be useful for monitoring during HRT.

Endometrium↗
PubMed1997

[The shrinkage of ovarian and uterine size and the decline of serum estradiol level in post-menopausal women].

OBJECTIVE: To investigate the shrinkage of ovarian and uterine size, and the decline of serum estradiol (E2) level in normal women. METHODS: Ovarian and uterine area of 92 perimenopausal and 292 postmenopausal women, measured by transvaginal ultrasonography, were analysed retrospectively and were compared with those of the controls consisting of 41 normal women in midfollicular phase, so did the serum E2 levels. RESULTS: As compared with the control group, ovarian area and endometrium thickness shrunk on an average of 30%, 2% and 56%, 48% in early perimenopausal and postmenopausal groups respectively. Serum E2 level and uterine area increased by 11% and 38% in early perimenopausal group, but decreased by 67% and 21% in postmenopausal groups respectively. No obviously further decline of serum E2 level was found 1 year after menopause, and of ovarian, uterine area 3-5 years after menopause. CONCLUSION: These data represent a normal profile of ovarian and uterine shrinkage and decline of serum E2 levels related to the time of menopause.

Adult↗
PubMed1996

Ligand stabilization of the beta 2 adrenergic receptor: effect of DTT on receptor conformation monitored by circular dichroism and fluorescence spectroscopy.

Treatment of the beta 2 adrenergic receptor with the reducing agent dithiothreitol (DTT) is known to abolish ligand binding to the receptor. Interestingly, the loss of binding can be prevented by preoccupation of the receptor with ligand. It is unclear, however, whether the ligand blocks access of DTT to the receptor, or the ligand stabilizes the receptor structure. In the present study, we have utilized circular dichroism (CD) and intrinsic tryptophan fluorescence to directly probe structural changes in the beta 2 adrenergic receptor in response to DTT treatment. Analysis of CD spectra of purified beta 2 receptor in the detergent micelle indicated that the receptor has an alpha-helix content of 60%, which is substantially more than what would be attributed to the seven transmembrane domains. The alpha-helix content was unchanged in the presence of DTT, suggesting that DTT treatment does not alter the secondary structure of the receptor. In contrast, the tryptophan fluorescence spectra demonstrated that DTT induces a reversible conformational change of the beta 2 receptor. Thus, DTT caused a red-shift in the maximum emission wavelength of the intrinsic tryptophan fluorescence. The change in emission spectrum correlated with a loss in the ability of the receptor to bind antagonist. Both changes in receptor binding and fluorescence emission were reversible, as removal of DTT allowed the receptor to restore 70% of ligand binding and return to the initial emission spectrum. Furthermore, we found adrenergic antagonists were able to slow the rate of the conformational change induced by DTT but not the rate of disulfide reduction, suggesting that the antagonists stabilize the structure of the reduced receptor.

Amino Acid Sequence↗
PubMed1996

Localization of leptin receptor mRNA expression in mouse brain.

The distribution of the leptin receptor in the brain of C57 mice was investigated using a non-radioactive in situ hybridization method. Leptin receptor mRNA expression was highest in the arcuate nucleus and median eminence of the hypothalamus, but it was also abundant in hippocampus, primarily in the dentate gyrus and CA1, and was detected at low levels in piriform cortex and the medial margin of the medial habenular nucleus. The localization of leptin receptor-containing neurones in the present study indicates the possibility that the leptin receptor is expressed on neuropeptide Y-containing neurones.

Animals↗