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Y Ni

Publications and source records attributed to Y Ni.

At least 109 records · Page 6Linked to original sources
PubMed1992

Strain-specific selection of genome segments in avian reovirus coinfections.

To determine whether selection of genome segments in coinfections is strain-specific, chicken embryo fibroblasts were coinfected with avian reovirus strain 883 and one of three other avian reovirus strains (176, S1133 and 81-5). Viral progeny from each coinfection (883 x 176, 883 x S1133 or 883 x 81-5) was serially passaged at a low m.o.i. The electropherotypes of the coinfection progeny and those of the plaque-derived clones obtained from passages 1 and 20 were analysed. Two 883 segments (M2 and S2) were found to be selected in the 883 x 176 coinfection, three 883 segments (M2, M3 and S2) in the 883 x S1133 coinfection, and only one 883 segment (M3) in the 883 x 81-5 coinfection, i.e. different 883 genome segments were selected in the three coinfections. It was, therefore, concluded that selection of genome segments in a coinfection of a given cell line is virus strain-specific. The selection of genome segments in coinfections was shown to be due to enhanced infectivity of the reassortants that were formed in the coinfections. In addition, defective interfering particles that lack the S1 segment were identified in the 883 x 81-5 coinfection progeny following serial passage. Selection of genome segment(s) in coinfections as described herein may have potential importance on the effect and production of divalent or multivalent vaccines.

Animals↗
PubMed1992

The thermostable direct hemolysin of Vibrio parahaemolyticus is a pore-forming toxin.

The hemolytic mechanism of thermostable direct hemolysin (TDH), a possible virulence factor of Vibrio parahaemolyticus, was studied. We demonstrated that TDH acts as a "pore-forming toxin" in temperature-dependent and -independent steps. The first temperature-dependent step requires only about 1-2 min incubation at 37 degrees C and makes a "pore" with a functional diameter of approximately 2 nm. The pore size was deduced from the molecular diameter of the colloidal inhibitory polysaccharides. The formation of the pores on TDH-treated erythrocyte membranes was also demonstrated by electron microscopic examination. The second step, which is a temperature-independent lytic step, causes the erythrocytes to swell owing to a colloidal osmotic influx of water via the "pores" into cells, resulting in erythrocyte lysis (or rupture) owing to increased intracellular pressure.

Erythrocytes↗
PubMed1992

Drop size stability assessment of fluorocarbon emulsions.

The aging of fluorocarbon emulsions prepared with natural egg yolk phospholipids (EYP) has been studied and a linear variation (r2 greater than 0.95) of the mean average volume of the droplets with time has been observed. The slope of the experimental lines, called "Stability Parameter, S" can thus be taken as a representation of the rate of aging of the emulsions. Examples are given of use of parameter S to assess the effect of formulation and processing parameters on the stability of diverse fluorocarbon emulsions. S is a useful tool to compare emulsions and ascertain any factors of stabilization/destabilization.

Blood Substitutes↗
PubMed1990

Futility of pericardiectomy for postirradiation constrictive pericarditis?

Two patients underwent pericardiectomy for postirradiation constrictive pericarditis. Both had received radiotherapy (more than 6,000 rads) for treatment of Hodgkin's disease 17 (patient 2) and 20 years (patient 1) earlier. At the time of operation, the patients were in New York Heart Association functional class III-IV or IV. Preoperative catheterization showed the following pressures for patients 1 and 2, respectively: right atrial, 30 and 14 mm Hg; right ventricular end-diastolic, 28 and 14 mm Hg; wedge, 29 and 13 mm Hg; and left ventricular end-diastolic, 27 and 14 mm Hg. Complete epicardiectomy and pericardiectomy was attempted in both patients. However, hospital mortality was 100%; patient 1 died of multiorgan failure after six days, and patient 2 died of biventricular failure after 3 months. A review of the literature revealed 44 cases of pericardiectomy for postirradiation constrictive pericarditis and a late survival rate of less than 50%. The poor results in these patients compared with patients having pericardiectomy for other reasons seem to be due mainly to the various kinds of radiation-induced damage to the heart as a whole, including untimely coronary artery disease, myocardial fibrosis, atrioventricular conduction disturbances, and valve dysfunction, with the result that complete relief by epicardiectomy and pericardiectomy may not be technically feasible.

Adult↗
PubMed1989

Purification of a TDH-related hemolysin produced by a Kanagawa phenomenon-negative clinical isolate of Vibrio parahaemolyticus 06: K46.

A hemolysin produced by a clinical isolate of Kanagawa phenomenon-negative Vibrio parahaemolyticus 06: K46 was purified by 55% ammonium sulfate fractionation and successive column chromatographies on DEAE-cellulose, hydroxyapatite, Sepharose 4B and Mono Q. The purified hemolysin was physicochemically and immunologically identical with the Vp-TRH (V. parahaemolyticus thermostable direct hemolysin related hemolysin) recently described in V. parahaemolyticus 03: K6 (Honda et al. Infect. Immun. 56: 961-965, 1988). This indicates that V. parahaemolyticus of Kanagawa-negative clinical isolates possessing not only 03: K6 but also different serotypes such as 06: K46 produce Vp-TRH. Production of Vp-TRH by most clinical isolates of Kanagawa-negative V. parahaemolyticus was also demonstrated. These results suggest the importance of Vp-TRH among clinical isolates of Kanagawa-negative V. parahaemolyticus.

Diarrhea↗
PubMed1989

Production of monoclonal antibodies against thermostable direct hemolysin of Vibrio parahaemolyticus and application of the antibodies for enzyme-linked immunosorbent assay.

A total nine hybridoma cell lines that produced monoclonal antibodies against thermostable direct hemolysin (Vp-TDH), a possible pathogenic toxin, of Kanagawa phenomenon-positive Vibrio parahaemolyticus was isolated and characterized. These monoclonal antibodies (mAbs) were divided into a minimum of five different specificity groups, including mAbs specific to Vp-TDH and common to Vp-TDH and Vp-TRH, a Vp-TDH-related hemolysin produced by Kanagawa phenomenon-negative V. parahaemolyticus. An enzyme-linked immunosorbent assay (ELISA) using mAb-1-D, a mAb specific for Vp-TDH, was developed for specific detection of Vp-TDH. On the other hand, the ELISA using mAb-9-D, and mAb common to both Vp-TDH and Vp-TRH, could be used for detection of both Vp-TDH and Vp-TRH. Thus, by combining these two ELISAs differential detection of Vp-TDH and Vp-TRH can be performed. Hence, the two ELISAs were applied for various strains of V. parahaemolyticus and it was found that most Kanagawa phenomenon-positive and -negative clinical isolates produced Vp-TDH and Vp-TRH, respectively, but all environmental strains, that were Kanagawa phenomenon-negative, produced neither toxin.

Animals↗
PubMed1989

Biological function of the rotavirus protein VP4: observations on porcine isolates from China.

Rotaviruses isolated from pigs in China were grown in MA104 cells. One tissue-culture-adapted isolate consisted of two subpopulations (variants), the RNA profiles of which differed in the relative migration of RNA segment 4 only. The variants were separated by plaque purification and by recovery from limiting dilutions and remained genetically stable. The variant possessing the slower migrating RNA segment 4, called 4S, grew faster and formed large plaques after 4-6 days incubation, whereas the variant possessing the faster migrating RNA segment 4, called 4F, grew more slowly and formed only microscopic plaques after 10-14 days incubation. The protein product of the 4F RNA occurred in much lower concentration in infected cells than the product of the 4S RNA. The RNA segments 4 of the two variants were found to be closely related when tested by dot hybridization under stringent conditions. The 4S RNA is more resistant to denaturation with methyl mercuric hydroxide than is the 4F RNA. The relevance of these findings to the biological functions of rotaviruses is discussed.

Animals↗
PubMedDate not supplied

Prolonged positive contrast enhancement with Gd-EOB-DTPA in experimental liver tumors: potential value in tissue characterization.

To evaluate the potential of the hepatobiliary magnetic resonance (MR) imaging contrast agent gadolinium EOB-DTPA (ethoxybenzyl diethylenetriaminepentaacetic acid) for the characterization of hepatic tumors, 79 primary and six implanted hepatomas in 38 rats were studied. MR imaging findings after administration of Gd-DTPA (0.3 mmol/kg) and Gd-EOB-DTPA (30 mumol/kg) were correlated with microangiographic and histologic findings. Gd-EOB-DTPA produced a strong liver enhancement, which caused prompt negative contrast enhancement (CE) in all implanted hepatomas and in 77 of 79 primary hepatomas. A positive CE that lasted up to 2 hours was found in two of 79 primary hepatomas, both of which were highly differentiated (grade I) hepatocellular carcinomas (HCCs). The rest were moderately differentiated to undifferentiated HCCs (grades II-IV). Rim enhancement, which corresponded histologically to peritumoral malignant infiltration sequestering normal hepatocytes, was seen around all implanted and some primary hepatomas. Positive tumor CE after administration of Gd-EOB-DTPA in this study is much less frequent but much more specific in comparison with the results of previous studies with manganese-DPDP (N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis[phosphate]). These findings may help further discriminate hepatic tumors.

Animals↗
PubMedDate not supplied

A tissue culture model for studying ethanol toxicity on embryonic heart cells.

A tissue system in which fibroblasts and myocytes from chick embryonic hearts were separately maintained was used to study the toxicity of ethanol. To reproduce the teratogenic effects of acute, high concentrations of ethanol typical of "binge" drinking, an open tissue culture system was employed. With open cultures, the cells were initially exposed to peak alcohol levels for approximately 6 hr and were exposed to decreasing concentrations of ethanol for the remainder of each 24 hr period. After the first day of ethanol exposure, there was substantial cell loss in both fibroblast and myocyte cultures. Alcohol-induced cell loss was dose-dependent. Despite decreased cell density after the first day of ethanol exposure, the surviving cells differentiated into monolayers of fibroblasts or beating cardiac muscle fibers. However, both ethanol-exposed fibroblasts and myocytes appeared atrophic, that is, smaller and shrunken. Electrophoretic analysis or these ethanol-exposed fibroblast and myocyte cultures revealed specific reduction in the cellular contents of alpha-actinin, myosin, and actin. These decreases in cytoskeletal proteins may be responsible for the morphological abnormalities noted in these cells.

Animals↗
PubMedDate not supplied

A review of the general aspects of radiofrequency ablation.

As an alternative to standard surgical resection for the treatment of malignant tumors, radiofrequency ablation (RFA) has rapidly evolved into the most popular minimally invasive therapy. To help readers gain the relevant background knowledge and to better understand the other reviews in this Feature Section on the clinical applications of RFA in different abdominal organs, the present report covers the general aspects of RFA. After an introduction, we present a simple definition of the energy applied during RFA, a brief historical review of its technical evolution, and an explanation of the mechanism of action of RFA. These basic discussions are substantiated with descriptions of RFA equipment including those commercially available and those under preclinical development. The size and geometry of induced lesions in relation to RFA efficacy and side effects are discussed. The unique pathophysiologic process of thermal tissue damage and the corresponding histomorphologic manifestations after RFA are detailed and cross-referenced with the findings in the current literature. The crucial role of imaging technology during and after RFA is also addressed, including some promising new developments. This report finishes with a summary of the key messages and a perspective on further technologic refinements and identifies some specific priorities.

Abdominal Neoplasms↗