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Biomedical subjects

B Jiang

Publications and source records attributed to B Jiang.

At least 199 records · Page 11Linked to original sources
PubMed1992

The Aeromonas hydrophila exeE gene, required both for protein secretion and normal outer membrane biogenesis, is a member of a general secretion pathway.

The Aeromonas hydrophila Tn5-751 insertion mutant L1.97 is unable to secrete extracellular proteins, and is fragile because of defective assembly of its outer membrane. A KpnI 4.1 kb fragment, which complements this mutant when supplied with an exogenous promoter, was isolated and sequenced. It contains two complete genes, exeE and exeF, plus fragments of two others and may form part of an operon. The exeE and exeF open reading frames encode 501-residue M(r) 55,882 and 388-residue M(r) 43,431 proteins, respectively. These genes were expressed in vitro and their initiation codons verified by deletion analysis. Tn5-751 had inserted near the centre of the exeE gene in the L1.97 strain. Subclones of the KpnI 4.1 kb fragment which contained only the exeE gene fully complemented the mutation, indicating that its function is required both for extracellular secretion and outer membrane assembly. ExeE and ExeF are highly similar to other proteins which have been shown to be involved in extracellular secretion, suggesting that an additional export apparatus beyond that required for inner membrane translocation may be part of the physiology of many Gram-negative bacteria.

Aeromonas hydrophila↗
PubMed1992

Evidence of serologic diversity within group C rotaviruses.

The Cowden strain of porcine group C rotavirus and the Shintoku strain of bovine group C rotavirus were classified as different serotypes by two-way cross-neutralization tests. Two neutralization patterns against the Cowden and Shintoku strains were observed when hyperimmune or convalescent-phase antisera to three noncultivatable porcine group C rotaviruses and a human group C rotavirus were used in one-way cross-neutralization tests. Antisera to two porcine group C rotaviruses and the human group C rotavirus neutralized the Cowden strain at high titers but did not neutralize the Shintoku strain, suggesting that these three strains are serotypically related to the Cowden strain. The remaining antisera to a porcine group C rotavirus (HF strain) reacted with the Cowden and Shintoku group C rotaviruses in cell culture immunofluorescence tests but did not neutralize either virus in one-way cross-neutralization, suggesting that the HF strain belongs to a third serotype. However, confirmation of these findings requires additional analysis by two-way cross-neutralization. Our findings support the existence of at least two distinct serotypes of group C rotaviruses, and possibly a third, among animals and humans. The serotypic similarity observed between the Cowden strain and a human group C rotavirus suggests that the cultivatable Cowden strain and antiserum to this virus may provide important reagents for the diagnosis of group C rotaviruses in humans.

Animals↗
PubMed1992

Detection of group C rotavirus antigens and antibodies in animals and humans by enzyme-linked immunosorbent assays.

Enzyme-linked immunosorbent assays (ELISAs) were developed to detect group (gp) C rotavirus antigens and antibodies. Both assays were confirmed to be specific for gp C rotavirus by using serogroup A, B, and C rotaviruses; hyperimmune antisera to these serogroups of rotaviruses; and paired serum specimens from animals infected with gp C rotaviruses. The ELISA for antigen detection reacted not only with porcine gp C rotaviruses but also with human and bovine gp C rotaviruses. Following experimental challenge of gnotobiotic pigs with porcine gp C rotavirus, the virus was found by ELISA in all diarrheic feces. A high prevalence of antibodies to gp C rotaviruses was detected in sera from adult pigs (93 to 97%) and cattle (47 to 56%) in the United States and Japan. However, no antibody to gp C rotavirus was detected in the sera (n = 20) of adult horses in the United States. In human sera from Hokkaido, Japan, 3% of children and 13% of adults possessed antibody to gp C rotaviruses. These results suggest that the ELISA that we developed may be useful for surveying gp C rotavirus infections in animals and humans. On the basis of serology, gp C rotavirus infections are common in pigs and cattle in the United States and Japan, but they occur at lower levels in humans from the Hokkaido area of Japan.

Animals↗
PubMed1992

Ventral horn cell responses to spaceflight and hindlimb suspension.

Spaceflight or hindlimb suspension results in a loss of mass and alterations of the metabolic and contractile protein profiles of skeletal muscles toward that resembling faster muscles. Given the influence of motoneurons on muscle properties, ventral horn cells of the lumbosacral enlargement of the spinal cord were studied to determine whether similar adaptations were present. Three groups of rats (5 per group) were studied: control, 14-day spaceflight, and 14-day hindlimb suspension. Spinal cords were quick-frozen, and the succinate dehydrogenase (SDH) activity and cross-sectional area of the soma of ventral horn cells were measured using a computer-enhanced image-processing system. Briefly, the optical density for SDH activity was determined after 8 min of incubation in a medium that gave a steady-state enzymatic reaction. Soma sizes were determined in cells with a visible nucleus. Although there were no significant differences among the three groups in mean cross-sectional area and SDH activity, the population distributions of both variables shifted significantly. In the flight rats, there was a shift toward smaller cells. Compared with control, the population distribution of SDH activities in the flight rats shifted toward higher activities, whereas the distribution shifted toward lower activities in the suspended rats. When considering the interactive effects within individual cells, there was a higher percentage of small cells with high SDH activities in the flight than in the control or suspended rats. These contrasting effects of spaceflight and hindlimb suspension suggest that the changes observed in ventral horn cells were due to factors other than simply the absence of weight support.

Animals↗
PubMed1992

Rat soleus muscle fiber responses to 14 days of spaceflight and hindlimb suspension.

Morphological and enzymatic responses in fibers expressing fast, slow, or both types of myosin heavy chain (MHC) were studied in rats after 14 days of spaceflight (COSMOS 2044) or hindlimb suspension. Although the percentage of slow-twitch fibers was unchanged, a higher percentage of fibers that expressed both slow and fast MHC was observed in flight and suspended rats than in synchronous ground-based controls. The soleus was 25 and 34% smaller than control after 14 days of flight and suspension, with the reduction in fiber cross-sectional area (CSA) being greater in slow- than in fast-twitch fibers in both experimental groups. The activities of succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (GPD) were not significantly affected by flight or suspension. The total SDH activity (i.e., SDH activity x CSA) decreased significantly in the slow-twitch fibers of the flight and the fast-twitch fibers of the suspended rats, in large part due to fiber atrophy. A shift in MHC expression in 14 and 9% of the fibers in flight and suspended rats occurred without a change in myosin adenosinetriphosphatase activity. The SDH and GPD activities of the fibers that expressed both slow and fast MHC were slightly higher than the slow-twitch fibers and slightly lower than the fast-twitch fibers. These data indicate that events were initiated within 14 days of spaceflight or suspension that began to reconfigure the protein profiles of 9-14% of the slow-twitch fibers from typical slow-twitch toward those of fast-twitch fibers, while all fibers were dramatically losing total protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1992

Adaptation of fibers in fast-twitch muscles of rats to spaceflight and hindlimb suspension.

The adaptation of single fibers in medial gastrocnemius (MG), a fast-twitch extensor, and tibialis anterior (TA), a fast-twitch flexor, was studied after 14 days of spaceflight (COSMOS 2044) or hindlimb suspension. Cross-sectional area (CSA) and succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar adenosinetriphosphatase (ATPase) activities were determined in fibers identified in frozen serial cross sections. Fibers were categorized as light, dark, or intermediate on the basis of myosin ATPase staining and alkaline preincubation and immunohistochemically as reacting with slow, fast, or both slow and fast myosin heavy chain monoclonal antibodies. Because there was a close relationship between these two means of categorizing fibers, all fibers were categorized on the basis of the immunohistochemical reaction. The percentage of slow- and fast-twitch fibers of the MG and TA were unchanged in either group. Mean fiber size of all fibers, irrespective of type, was unaffected in either muscle after flight or suspension. The fibers that expressed both fast and slow myosin heavy chains were smaller than control in the MG of both experimental groups. Compared with control, the SDH and total SDH activities in the MG were significantly less in suspended rats, with the fast-twitch fibers showing the largest difference. The ATPase activity in the MG was higher in flight than in control or suspended rats. There were no significant effects of flight on fibers of the TA. In contrast, the TA in suspended rats had higher GPD activities than either control or flight rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1992

Cardiac cycle length variability in ponies at rest and during exercise.

We evaluated cardiac cycle length variability in ponies at rest and during strenuous exercise with and without premedication with atropine. In the absence of premedication, cardiac cycle length at rest was 1,112 +/- 53 ms, the individual cardiac cycle length standard deviation (SDCL) was 75 +/- 23 ms, and the individual cycle length coefficient of variation (CVCL) was 6.32 +/- 1.62. Exercise significantly decreased (P < 0.05) all three indexes (290 +/- 9 ms, 5 +/- 1 ms, and 1.65 +/- 0.20, respectively). Atropine premedication significantly reduced resting cardiac cycle length (685 +/- 46 ms), SDCL (10 +/- 2 ms), and CVCL (1.45 +/- 0.19) compared with nonpremedicated values. Cardiac cycle length was significantly decreased by exercise after atropine premedication, but no statistically significant changes occurred in SDCL or CVCL. Thus, although considerable cardiac cycle length variability exists in nonpremedicated ponies at rest, it is nearly completely abolished by strenuous exercise. The absence of significant differences between the indexes of variability during exercise without premedication, at rest after atropine, and during exercise after atropine indicates that cardiac cycle length variability in the pony is mediated primarily through activity of the parasympathetic system.

Animals↗
PubMed1992

[Clinical analysis of 60 cases of pregnancy with thrombocytopenia].

Sixty cases of pregnancy with thrombocytopenia were analyzed. Bleeding syndrome was found in 36 patients during pregnancy, with 7 cases suffering from massive hemorrhage during delivery and a postpartum hemorrhage rate of 11.7%. There was a negative correlation between the platelet level and the amount of bleeding during gestation and delivery. We suggest that cortico steroid is necessary with a platelet count less than 50 x 10(9)/L in the middle or late trimester of pregnancy to reduce the bleeding tendency during delivery, as well as the incidence of thrombocytopenia in the newborn infant use of excessive platelet transfusion is not encouraged, since it implicates an increase in antibody-induction (PAIG) and probability of C type hepatitis in the recipient. Platelet transfusion should be reserved only for the treatment of serious hemorrhage. There were 53 newborn infants, 7 of whom (13.2%) suffered from thrombocytopenia, with a mortality of 1.9% (7/53) during the perinatal.

Adult↗
PubMed1992

Reversal of doxorubicin resistance by tetrandrine in Chinese hamster ovary cell line.

Tetrandrine (Tet) 0.5 microgram.ml-1 and 1 microgram.ml-1 potentiated 2.88- and 4.3-fold growth-inhibitory effects of doxorubicin (Dox) in Chinese hamster ovary cell line (CHO), respectively, while Tet 1 microgram.ml-1 and 2.5 micrograms.ml-1 potentiated 7.3- and 8.4-fold in its resistant cell line (CHO/Dox), respectively. The colony-forming efficiencies were reduced in CHO and CHO/Dox when the cells were treated with noncytotoxic doses of Tet 2.5 micrograms.ml-1 and 5 micrograms.ml-1 in combination with different concentration of Dox. Increase in accumulation of Dox in CHO/Dox cells was shown by fluorometry. The result indicated that Tet reversed the resistance to Dox in CHO/Dox cells.

Alkaloids↗
PubMed1992

[Effects of imipramine on isolated rabbit basilar artery].

Imipramine (Imi) inhibited the contractile response to BAY k 8644 (IC50 = 2.39 +/- 0.33 mumol.L-1), KCl (IC50 = 1.00 +/- 0.09 mumol.L-1), in rabbit basilar artery rings. Imi was more effective in suppressing the contractile response evoked by KCl, CaCl2, and 5-HT in basilar artery rings than in mesenteric artery rings. The effect of Imi was the same as that of diltiazem (Dil). There was no difference between the inhibitory response of Imi on contraction induced by KCl in basilar artery rings with or without endothelium. The results suggest that Imi may block the calcium channel and inhibit the rabbit basilar artery selectively, and the effect is endothelium-independent.

Animals↗
PubMed1992

[Effects of trihexyphenidyl on slow action potentials in guinea pig papillary muscles].

Effects of trihexyphenidyl (THP) were examined on the slow action potentials (SAP) induced by isoproterenol (Iso), histamine (His), Bay k 8644 or tetrodotoxin (TTX), in guinea pig papillary muscles. THP 10, 50, and 100 mumol.L-1 depressed the maximal upstroke velocity (Vmax) and the action potential amplitude (APA) of SAP. These effects were reversed partially by the elevation of the concentration of calcium from 2.0 to 5.6 mmol.L-1. The results suggest that THP can inhibit calcium inflow in myocardium.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

DNA content and its relationship with pathology and prognosis of colorectal carcinoma.

The DNA content of 181 colorectal cancers was investigated by flow cytometry on paraffin-embedded specimen. The relationship of flow cytometric DNA patterns of colorectal cancer to Dukes's stage, histological type and grade, tumor size and patient's prognosis were analysed. The DNA aneuploid carcinomas were found in 53.04% of the patients (hypodiploid 22.10%, hyperdiploid 20.99%, polyploid 9.94%). Diploidy was found in 46.96% of the patients with colorectal cancer. The proportions of aneuploidy were significantly lower in the patients with Dukes' stage A (25.00%) and B (47.14%) than those with Dukes' stage C (64.71%) and D (68.42%). Aneuploid frequency was higher in the patients with poorly differentiated adenocarcinoma (84.62%), mucinous adenocarcinoma (62.50%) and tubular adenocarcinoma (52.75%) than those with villous adenocarcinoma (22.86%). The proportion of aneuploidy was significantly higher in the patients with poorly differentiated tumor (71.79%) than in those with moderately (50.00%) and well differentiated tumors (44.83%). Five-year survival rate of the patients with DNA aneuploid tumors was 33.80% compared with 66.67% of those with diploid tumors. Analysis of Cox regression revealed that DNA ploidy and Dukes' stage significantly influenced the patient's prognosis. It is suggested that DNA ploidy might be an important prognostic factor in colorectal cancer.

Adenocarcinoma↗
PubMed1992

[Role of catecholamines in action of nicotine on slow action potentials in guinea pig papillary muscles].

The action potential duration (APD) of histamine-induced slow action potentials (SAP) and force of contraction (FC) were potentiated by nicotine (0.6-1.0 mmol.L-1) on guinea pig papillary muscles in a concentration-dependent manner. In the presence of atropine, nicotine concentration dependently suppressed the action potential amplitude (APA), APD, the maximal upstroke velocity (Vmax), and FC in catecholamine-depleted (reserpine 2.5 mg.kg-1 ip, 15 h prior to the experiment) muscles. Nicotine (0.6 mmol.L-1) itself induced SAP and enhanced FC. These 2 effects were antagonized by verapamil. A linear relationship existed between APA of nicotine-induced SAP and 1g [Ca2+]0 with a slope of 23.2 mV for a 10-fold change in [Ca2+]0. These results suggested that the effects of nicotine on enhancing Isi were mediated by the release of catecholamines in myocardium.

Action Potentials↗
PubMed1992

Mathematical modelling of post-exercise heart rate recovery in ponies.

Using a recently developed nonlinear algorithm which identifies reference points on left ventricular pressure waveforms and other waveforms, we analyzed heart rate recovery in ponies after strenuous treadmill exercise. Each pony performed exercise tests with and without premedication with atropine methyl nitrate. Resting and exercise heart rates were 54 +/- 3 and 209 +/- 6 beats/min, respectively, without premedication and 85 +/- 8 and 212 +/- 5 beats/min, respectively, following atropine premedication. Post-exercise heart rate recovery without premedication was best described by a biexponential curve with a rapid initial period (duration = 55 +/- 6 sec, Tl/e = 15 +/- 2 sec) and a slower secondary period (duration = 267 +/- 5 sec, Tl/e = 455 +/- 78 sec). After atropine premedication, heart rate recovery followed a monoexponential curve (Tl/e = 174 +/- 46 sec) in 4 ponies, but remained biexponential (Part 1 duration = 74 sec, Tl/e = 20 sec; Part 2 duration = 243 sec, Tl/e = 342 sec) in the other ponies. The calculated time required for heart rate to return to resting levels after atropine premedication was 11.3 +/- 2.2 min, compared to 26.3 +/- 3.9 min without premedication. However, without premedication, only 6.6 +/- 1.6 min were required to reach the post-atropine resting heart rate, indicating that the time difference was due to the higher resting heart rate after atropine premedication. Thus, heart rate recovery in the non-premedicated pony follows a biexponential curve similar to that observed in other species.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1991

Calcium reveals different mechanisms of guanylate cyclase activation by atrial natriuretic factor and ATP in rat lung membranes.

CaCl2 inhibited ATP-stimulated guanylate cyclase activity, but had little effect on basal and atrial natriuretic factor-stimulated guanylate cyclase activity in rat lung membranes. LaCl3 had similar effects as CaCl2 on basal and stimulated guanylate cyclase activity. LiCl and other monovalent salts inhibited ATP-stimulated guanylate cyclase activity more than basal enzyme activity. However, atrial natriuretic factor somehow stabilized the enzyme against the inhibitory effect of LiCl. These results suggest that ATP and atrial natriuretic factor activate the enzyme through different mechanisms. Since the effect of calcium on guanylate cyclase activity is different from that of monovalent salts and can be mimicked by lanthanum, it may be mediated by a specific calcium binding site or binding protein.

Adenosine Triphosphate↗
PubMed1991

Comparison of human and porcine group C rotaviruses by northern blot hybridization analysis.

The genetic relationship between human and porcine Gp C rotaviruses and between Gp C and Gp A or B rotaviruses was examined by Northern blot hybridization. Cross-hybridization studies using radiolabeled ssRNA transcript probes demonstrated that the human and porcine Gp C rotaviruses shared a high degree of nucleotide sequence homology in most of the eleven gene segments; the greatest sequence divergence was observed in gene 7. Neither the human nor the porcine Gp C probe hybridized strongly with gene segments from Gp A reference strains or a Gp B bovine rotavirus. These data indicate that genetically, porcine and human Gp C rotaviruses are closely related, whereas they are quite distinct from Gp A or B suggesting that porcine and human Gp C rotaviruses may have evolved from a common ancestral source.

Animals↗
PubMed1991

[The study of Bacillus sphaericus Ts-1 protoplast-plasmid transformation of electroporation].

This report gave the best conditions of Bacillus sphaericus Ts-1 protoplast-plasmid pHV33 electroporation. The highest transformation frequency and transformation efficiency induced by three pulse of 21 KV/cm and 10 microseconds duration applied at an interval of one sec., was 2.44 x 10(2) transformants/micrograms DNA and 3.16 x 10(-6) respectively. The saturated concentration of DNA absorbed by the protoplast was 5 micrograms DNA/10(9) cells/ml. By means of this method, pJB417, a recombinant mosquito larvicide clone, was introduced into B. subtilis 168M and B. sphaericus Ts-1. The transformants of B. subtilis 168M with biocide activity were obtained, but the toxicity of B. sphaericus Ts-1 was not increased.

Animals↗