Search PubMed⌕ Search

Biomedical subjects

J Shen

Publications and source records attributed to J Shen.

At least 415 records · Page 23Linked to original sources
PubMed1995

Expression of the erythrocyte antigen Henshaw (He; MNS6): serological and immunochemical studies.

Production of murine monoclonal antibodies to the low prevalence MNS antigen Henshaw (He; MNS6) has enabled more detailed study of this antigen. Using these directly hemagglutinating anti-He, red blood cells (RBCs) from 1695 people of African origin were screened in the USA and England. The prevalence of He+ samples among these donors was 2.1%. In Natal, blood samples from 1218 black donors were screened with rabbit anti-He. The prevalence of He+ donors in this population was 7.0%. Immunoblotting confirmed that the He antigen is carried on an erythrocyte membrane component with a molecular mass that is indistinguishable from glycophorin B. Hemagglutination and immunoblotting demonstrated that ten of 56 He+ samples tested more extensively had a reduced expression of the He antigen. The majority of He+ RBCs were S+; those He+ RBC samples that were S-s+ more frequently had a weakened expression of He.

Antibodies, Monoclonal↗
PubMed1995

Relationship between colonial morphology and adherence of Streptococcus pneumoniae.

Phase variants in colonial opacity of pneumococci differ in the ability to colonize the nasopharynx of infant rats. To explain this observation at a cellular level, we compared the ability of opacity variants to adhere to buccal epithelial cells, type II pneumocytes, or vascular endothelial cells and to the glycoconjugates that represent the cognate receptors at each of these sites. The transparent phenotype was associated with enhanced adherence to buccal cells (approximately 100%) and their receptor relative to that of the opaque variants. Only modest differences in adherence (< 45%) were demonstrated to resting lung and vascular cells. In contrast, adherence of transparent variants increased by 90% to lung cells stimulated with interleukin-1 and by 130% to endothelial cells stimulated with tumor necrosis factor. In contrast, cytokine stimulation did not influence the adherence of opaque pneumococci. This difference correlated with the unique ability of transparent variants to adhere to immobilized GlcNAc and to cells bearing transfected platelet-activating factor receptors. These results suggest that the mechanism of enhanced colonization of the nasopharynx in vivo by transparent as compared with opaque phase variants involves a greater ability to adhere to both GlcNAc beta 1-3Gal on buccal epithelial cells and GlcNAc and PAF receptors on cytokine-activated, as opposed to resting, lung and endovascular cells.

Bacterial Adhesion↗
PubMed1995

Cell dissociation with papain reduces the density of cGMP-activated channels of the retinal rod.

A proteolytic enzyme, papain, is the enzyme commonly used for dissociation of retinal neurons. To ask whether papain modifies the activity of ion channels, cGMP-activated channels were recorded in inside-out membrane patches excised from the bullfrog rod outer segment, and the activity was compared between cells dissociated using papain and cells dissociated mechanically. While the affinity to cGMP, I-V relation, channel kinetics, and single-channel current amplitude were almost the same in both papain-treated and the control preparations, the total current flowing through the patch membrane of the papain-treated cells was reduced to about 20% of the control, suggesting that papain reduced the density of cGMP-activated channels.

Animals↗
PubMed1995

[A comparative morphologic study of Carabelli cusp between Chinese and Japanese students.].

The study of teeth,dentition and occlusion is helpful to guide oral medical clinic and the study of anthropology.Our department of Osaka Dental University and had many items of research work about teeth,dentition and occlusion between Chinese and Japanese students.This article reports the study of Carabelli cusp.The results revealed:(1)the rate of Carabelli cusp is higher in Japanese than in Chinese and is higher in male than in female.(2)the rate of Carabelli cusp of the first maxillary molar of both side is very high.(3)The rate of Carabelli cusp is related to the height and the type of cusp numbers.These all illustrated the occurence of Carabeiil cusp were influenced by race, individual and the development of teeth.

English Abstract↗
PubMed1995

Dental vacuum system with skirt technology.

A heat-sterilizable vacuum system (Legend) featuring a skirt technology that confines the user's hand to the sterile instruments during initial hose coupling and during patient treatment is described. Because the user does not grasp the non-sterile vacuum hose connector and hose, plastic barriers and mandatory disinfection of the hose connector, hose, and instrument holders after each patient are not necessary. The vacuum system described promotes asepsis by using sterile vacuum instruments, encourages sound asepsis practice, prevents cross-contamination, and is cost-effective.

Dental Equipment↗
PubMed1995

Hypercapnic acidosis and dimethyl amiloride reduce reperfusion induced cell death in ischaemic ventricular myocardium.

OBJECTIVE: The aim was to investigate the effects of slowing the recovery of ischaemia induced intracellular acidosis with hypercapnic acidosis or dimethyl amiloride (DMA) on the extent of reperfusion induced cell death. METHODS: Isolated arterially perfused rabbit papillary muscles and septa were suspended in a controlled atmosphere and perfused with a modified Tyrode solution containing erythrocytes and trypan blue (500 microM). Ischaemia was produced by arrest of perfusion and withdrawal of atmospheric O2. Extracellular pH of the muscle during reperfusion was controlled by adjusting the pH of the perfusate (pH 6.6 or pH 7.6 with and without DMA 20 microM) and changing the PCO2 of the chamber atmosphere. After 30 min of reperfusion following 30 min (group A) or 60 min (group B) of ischaemia, papillary muscles were fixed with paraformaldehyde. Cell death was assessed by trypan blue staining of nuclei in histological sections of the papillary muscles. RESULTS: The magnitude of cell death was greatest after reperfusion with pH 7.6 as measured by the percentage of nuclei staining with trypan blue (15.1% in group A; 41.8% in group B). By contrast, reperfusion at pH 6.6 reduced cell killing (group A, 3.6%; group B, 7.2%). Reperfusion at pH 7.6 with DMA (20 microM) also reduced trypan blue uptake (group A, 2.8%; group B, 3.8%). Despite the attenuation of cell death afforded by acidosis or Na+/H+ exchange inhibition, significant swelling of the extracellular space and microvascular injury was noted. CONCLUSIONS: Hypercapnic acidosis and Na+/H+ exchange inhibition during reperfusion attenuate lethal reperfusion injury to ventricular myocardium and extend to the intact myocardium the concept of the "pH paradox" in which recovery of intracellular pH after reperfusion is a precipitating factor in lethal cell injury.

Acidosis↗
PubMed1995

Adherence status regulates the primary cellular activation responses to the flavivirus West Nile.

Increases in cell-surface intercellular adhesion molecule-1 (ICAM-1; CD54) and major histocompatibility complex antigen class I (MHC-I) and class II (MHC-II) expression during flavivirus infection of murine macrophages was strongly dependent on adherence status. CD54 and MHC expression was significantly increased during infection with the flavivirus West Nile (WNV) on adherent, but not on non-adherent, macrophages. In contrast, increased CD54 and MHC-I expression was induced by interferon-gamma (IFN-gamma) in both cultures but was significantly greater on adherent cells than non-adherent cells. Adherent status was also important in human embryonic fibroblasts (HEF), adherent cells of non-immune origin. Similar to macrophages, WNV induced increased CD54 or MHC-I expression on adherent but not non-adherent HEF. Again, induction of these antigens by IFN-gamma occurred in both cultures but was significantly greater on adherent cells than non-adherent cells. Macrophages or HEF that aggregated when cultured at high density under non-adherent conditions, responded to WNV and IFN-gamma in a manner similar to adherent cells. Unresponsive non-adherent cells infected with WNV or treated with IFN-gamma under non-adherent conditions for 24 or 48 hr recovered if transferred to adherent culture conditions for 24 or 48 hr. Moreover, these cells expressed significantly higher cell-surface CD54 and MHC-I concentrations, compared to similarly treated HEF cultured under adherent conditions during the entire culture period. WNV infection also induced significant nitric oxide production in macrophages, and adherence status was similarly important in this response, with adherent cells producing higher amounts of nitrite/nitrate than non-adherent cells. These results suggest that adherent status may be critical for effective antiviral immune responses involving macrophages.

Animals↗
PubMed1995

[Evaluation of segregation ratio and hereditability of esophageal cancer--a comparative epidemiologic study in Huai'an County].

A genetic epidemiologic case-control study including 407 pedigrees (249 cases and 158 controls) was carried out to estimate the segregation ratio and the hereditability (h2) of esophageal cancer by using the method of Li-Mantel-Gart and Falconer, respectively, and to compare the genetic epidemiologic features from the other cancers. The results showed that the segregation ratio of esophageal cancer was 0.1347, significantly less than 0.25 and the genetic model belonged to polygenetics. The h2 of esophageal cancer was 21.41%, 20.23% for female and 13.57% for male. It is concluded that genetic factor is one of the risk factors for esophageal cancer and specially of importance for female, but it is not a main risk factor for esophageal cancer. The results of comparative epidemiologic study among the cancers of lung, stomach, liver and large bowel showed that the segregation ratios of the cancers (except stomach, no data) were all less than 0.25, and the h2 of gastric and liver cancers were higher, which were 52.40% and 51.85%, respectively.

Case-Control Studies↗
PubMed1995

[Patella resurfacing and patellofemoral resurfacing].

Since 1983 isolated polyethylene patellar prosthesis was used for patella resurfacing of 19 patients with patellofemoral osteoarthritis. After an average of 44.9 months follow-up, the treatment was found to be not as satisfactory as earlier trials. The main reason was the wide erosion of femoral condyle caused by the polyethylene patella. To overcome this shortness, a new type of patellofemoral prosthesis was designed by the authors, which was named Y-L-Q. From January, 1991 to November, 1993, this prosthesis was used to treat 16 knees of 13 patients with patellofemoral osteoarthritis. Most of those patients improved both symptomatically and functionally. The good to excellent results rate was 87.5% (14/16 knees) at the time of an average 10 month follow-up. The early results of our experience with patellofemoral resurfacing are encouraging, and extended follow-ups are in progress.

Aged↗
PubMed1995

Changes of nitric oxide and protective effects of nitric oxide inhibitors in newborn rats with sepsis.

In a newborn rat model of sepsis, the changes of nitric oxide and the protective effects of methylene blue or/and dexamethason were investigated. The results revealed that plasma nitric oxide levels were elevated at 6 h and peaked at 12 h after bacterial challenge. The treatment with methylene or/and dexamethasone was found to blunt hypoglycemia and hyperlacticemia, to reduce the occurrence rate of loss of response to pain, and to prolong the survival time. Moreover, therapy by dexamethasone was shown to decrease the 24 h mortality. The results suggested that nitric oxide play an important role during the course of fatal P. aeruginosa sepsis, but it is clear that the clinical value of nitric oxide and its inhibitors need to be further studied.

Animals↗
PubMed1995

[Surgical treatment of obstructive jaundice caused by hepatocellular carcinoma].

Between Jan. 1991 and Dec. 1993, 7 patients with obstructive jaundice caused by hepatocellular carcinoma underwent transcholedochal cancerous embolectomy plus T-tube drainage of the biliary tract, in 5 patients with hepatectomy. Detailed discussion was made an the operative procedure and the operative results. The authors indicated that intensive surgical operation is effective in relieving symptoms and prolonging life-span.

Adult↗
PubMed1995

[Serogroups, virulence and hemolytic activity of Aeromon as hydrophila which caused fish bacterial septicaemia].

A new infected disease called bacterial septicaemia occurred in cyprinid fish throughout China during 1989-1992. A. hydrophila was known as the most important pathogen of this harmful disease. Thirty-three strains of A. hydrophila, most isolated from moribund fishes, were serogrouped by tube-agglutination with rabbit antisera. Most of the isolates could be grouped into two serotypes, TPS-30 and PBJS-76. These two groups could be found not only in Zhejiang province but in other province in south China. It can be concluded that the two serogroups were the main Aeromonas groups caused this fish disease. These isolates were virulent to Carassius auratus, with LD50 values of 10(4) to 10(6). The hemolytic activity ranged from titers of 1/8 to 1/16. No relationship were observed with the hemolytic activity and virulence.

Aeromonas hydrophila↗
PubMed1995

[Surgical treatment of spinal tumors: a report of 30 cases].

With the advance of spinal surgery in the last decade, surgical treatment of spinal tumors has been no longer limited to sole laminectomy. The principles of surgical treatment of spinal tumors include: (1) anterior approach for the anterior lesion and posterior approach for the posterior lesion, (2) combined anterior and posterior approach for extensive lesions and (3) internal fixation for spinal stability. 30 cases of spinal tumors were treated on the basis of the above guiding principles and 83.3% (25 of 30 cases) showed excellent or good outcomes.

Adult↗
PubMed1994

Persistent increase of hippocampal presynaptic axon excitability after repetitive electrical stimulation: dependence on N-methyl-D-aspartate receptor activity, nitric-oxide synthase, and temperature.

The electrical excitability of Schaffer collateral axons and/or terminals was studied in hippocampal slices by monitoring single, CA3 pyramidal neurons activated antidromically from CA1 stratum radiatum. At 22 degrees C, weak, repetitive stimulation with as few as 10 impulses at 2 Hz led to a robust lowering of the antidromic activation threshold that lasted > 30 min. The effect was completely absent at 32 degrees C and was blocked by both the N-methyl-D-aspartate receptor antagonist, 2-amino-5-phosphonovalerate and the inhibitor of nitric-oxide synthase, L-nitro-arginine methyl ester. Such threshold lowering would alter the variance of synaptic responses from axons stimulated in the variable excitation region of their input-output functions. These results thus raise important doubts about the interpretation of experiments in which the so-called minimal-stimulation method has been used at reduced temperature to infer changes in quantal transmission during hippocampal long-term potentiation. In the present experiments, no changes were observed in the estimate of excitatory postsynaptic potential quantal content in long-term potentiation experiments at either temperature, which could not be accounted for by an artificial, temperature-dependent change in the responsiveness of presynaptic axons.

Amino Acid Oxidoreductases↗
PubMed1994

Na(+)-dependent high affinity uptake of L-glutamate in primary cultures of human fibroblasts isolated from three different types of tissue.

Cultured human fibroblasts isolated from embryonic muscle, skin and peripheral nerve tissues were found to accumulate [3H]L-glutamate by a Na(+)-dependent uptake process strongly inhibited by several glutamate/aspartate analogues including D- and L-aspartate, D- and L-threo-3-hydroxyaspartate and L-trans-pyrrolidine-2,4-dicarboxylate but not D-glutamate. It was also reduced by elevated concentrations of K+, Rb+ and Cs+. The values of Km's were 5-20 microM, well within the 'high affinity' region. Variations in the capacity (Vmax) of [3H]L-glutamate uptake did not correlate with the origin (muscle, skin or nerve tissue) of the fibroblasts. The uptake characteristics suggest that it is mediated by a transport system similar to that commonly observed only in brain tissue.

Aspartic Acid↗
PubMed1994

The fern Polypodium decumanum, used in the treatment of psoriasis, and its fatty acid constituents as inhibitors of leukotriene B4 formation.

The fern Polypodium decumanum, commonly called Calaguala, has a clinically documented use in South America and Spain in the treatment of psoriasis. One of the inflammatory mediators isolated in abnormally high quantities in the psoriatic skin is leukotriene B4 (LTB4). Calaguala was tested in an in vitro model using human leukocytes for its ability to inhibit the LTB4 formation. The inhibition was found to be caused by the polyunsaturated fatty acids (PUFAs) linoleic, linolenic and arachidonic acid. IC50 values were determined for the isolated acids and compared to a group of closely related acids also commonly found in nature. The IC50 values for most acids tested were of the same magnitude (20-60 microM) except for arachidonic acid which showed stimulatory activity and 8(R) hydroxylinoleic acid which gave 30% inhibition with the highest dose tested (120 microM). The amounts of PUFAs in different Calaguala extracts were quantitatively analysed and it is concluded that the fatty acid constituents of Calaguala may contribute to the clinical effects of the extract.

Chromatography, High Pressure Liquid↗
PubMed1994

Ultraviolet solid-state laser (213-nm) photorefractive keratectomy. In vivo study.

BACKGROUND: The pulsed ultraviolet 213-nm solid-state laser has been demonstrated as an alternative to the gas argon-fluoride 193-nm excimer laser for photorefractive keratectomy (PRK). The authors studied the clinical course and histopathologic changes occurring in rabbit corneas after PRK with a 213-nm solid-state laser. METHODS: The 213-nm output of neodymium:YAG frequency-quintupled laser was used to create 5-mm optical zone ablations in seven pigmented rabbit corneas. The radiant exposure was 250 mJ/cm2 delivered through a computer-controlled scanning delivery system with a spot size of 0.5 mm. The target ablation was 4.0 diopters with an estimated ablation depth of 40 microns. A clinical estimate of corneal epithelial healing and stromal haze was made at intervals over the 3-month study period. Animals were killed immediately after ablation, or at 10 days, 1 month, or 3 months after ablation. Corneal tissue was preserved for light microscopy and transmission electron microscopy at each study interval. RESULTS: All corneas re-epithelialized within 10 days postoperatively. Anterior stromal haze was clinically visible at 3 days, increased until approximately 1 month, and then gradually decreased over the succeeding 2 months. Residual subepithelial haze was visible at 3 months. Results of histopathologic study documented normal epithelium healing over time; the basement membrane retained its regular thickness and hemidesmosomes were abundant at 3 months. The anterior stroma had an increased number of fibroblasts at 10 days, many of which remained until 1 month. A mild, transient, cellular reaction occurred throughout the thickness of the stroma and the endothelium. CONCLUSION: Using the 213-nm ultraviolet solid-state laser with a scanning delivery system, PRK shows a similar clinical course and histopathologic findings to the 193-nm excimer PRK study in rabbits. It is a clinically viable procedure for refractive surgery and requires further human clinical trails to determine its efficacy.

Animals↗