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Biomedical subjects

G Wu

Publications and source records attributed to G Wu.

At least 451 records · Page 25Linked to original sources
PubMed1996

The cytochrome bc1 complex but not CycM is necessary for symbiotic nitrogen fixation by Rhizobium leguminosarum.

Following Tn5 mutagenesis of Rhizobium leguminosarum biovar viciae, two mutants in one complementation group were identified as being unable to fix nitrogen in pea nodules. Spectroscopic analysis revealed that the mutants had lowered levels of c-type cytochromes and cytochromes aa3, but increased levels of cytochrome d. Cells of the mutants were greatly reduced in their ability to oxidize the artificial electron donor N,N,N',N'-tetramethyl-p-phenylenediamine but membranes prepared from them had increased levels of succinate- and NADH-dependent respiration. NADH oxidation by the mutants was insensitive to the respiratory inhibitor antimycin A, that targets the cytochrome bc1 complex. Molecular analysis of the mutants revealed that they were affected in the cytochrome bc1 complex. One of the mutants contained Tn5 in a gene homologous to that encoding cytochrome c1, and in the other the Tn5 was in DNA homologous to that encoding the cytochrome b component of the cytochrome bc1 complex. Haem staining revealed that haem proteins of M(r)31,000 and M(r)23,000 were absent from membranes from the mutants whereas an additional soluble c-type cytochrome protein of M(r)23,000 was present. We conclude that the larger of these two haem proteins corresponds to cytochrome c1 and, in its absence, the protein of M(r)23,000 does not remain associated with the membrane. Formation of this M(r)23,000 component was specifically blocked in a third respiratory-defective mutant which contained Tn5 in a region of DNA showing homology to a Bradyrhizobium Japonicum gene previously shown to encode the membrane-bound c-type cytochrome CycM. Although the cytochrome bc1 complex is essential for symbiotic nitrogen fixation, the other membrane-bound c-type cytochrome (CycM) is not.

Amino Acid Sequence↗
PubMed1996

The study of kinematic transients in locomotion using the integrated kinematic sensor.

A system based on the integrated kinematic sensor (IKS) was used to study the three-dimensional (3-D) kinematics of human lower limb during walking and running. The linear displacement, angular velocity, and linear acceleration of the foot, shank, and thigh segments were directly measured using three IKS's. The results clearly showed the heel strike impact in both walking and running, illustrating the high frequency components that exist in those activities. This paper illustrates the limitations of standard position measurements to capture transients associated with phase transitions, not only in acceleration estimates, but also in the determination of segmental angular velocities. An error analysis was conducted to determine the relative contribution of the accelerometer and the angular rate sensor to the determination of the segmental center of mass (COM) acceleration. The results suggest that in practical kinesiological applications, adding either an accelerometer or an angular rate sensor can remarkably increase the accuracy of segmental COM acceleration estimates.

Acceleration↗
PubMed1996

An important role for endogenous synthesis of arginine in maintaining arginine homeostasis in neonatal pigs.

This study was designed to test the hypothesis that endogenous arginine synthesis plays an important role in maintaining arginine homeostasis in neonatal pigs. Gabaculine was used as a suicide inhibitor of ornithine aminotransferase to decrease the intestinal conversion of glutamine-derived pyrroline-5-carboxylate (P-5-C) into ornithine, the precursor of both citrulline and arginine. Four-day-old suckling pigs received oral administration of 0.0 or 0.83 mg gabaculine/kg body wt every 4 h during a 12-h period from 6 A.M. to 6 P.M. Blood was collected from piglet's jugular vein at 6 A.M. and 6 P.M. after a 2-h isolation from sows. Gabaculine treatment decreased plasma concentrations of ornithine, citrulline, and arginine by 59, 52, and 76%, respectively, and increased those of glutamine and proline by 74 and 220%, respectively. The gabaculine treatment also increased plasma concentrations of leucine, taurine, and ammonia by 29, 42, and 20%, respectively. There were no differences in intramuscular concentrations of amino acids between control and gabaculine-treated pigs. Because P-5-C synthase (the enzyme required for synthesis of P-5-C from glutamate) was almost exclusively located in enterocytes of 4-day-old pigs, our data suggest that the intestinal production of citrulline plays an important role in endogenous synthesis of arginine and its homeostasis in neonatal pigs.

Administration, Oral↗
PubMed1996

Tissue-specific expression of the human brain natriuretic peptide gene in cardiac myocytes.

Brain natriuretic peptide (BNP) is a cardiac hormone constitutively expressed in the adult heart. To identify the cis-acting elements involved in regulation of the human BNP gene, we subcloned the full-length promoter (-1818 to +100) and deletions thereof upstream from a luciferase reporter gene and transiently transfected them into primary cultures of neonatal rat atrial and ventricular myocytes and myocardial fibroblasts. Luciferase activity of the full-length construct was higher in ventricular (39064 +/- 8488 relative light units, N=11) and atrial (11225 +/- 1907, N=17) myocytes than myocardial fibroblasts (329 +/- 113, n=5). Maximal promoter activity in ventricular and atrial myocytes was maintained by sequences positioned between -1818 and -1283 relative to the transcription start site. Deletion to -1175 resulted in a decrease, whereas further deletion to -500 effected an increase in reporter activity in both cell types. In ventricular and atrial myocytes, deletion from -500 to -40 reduced luciferase activity 20-fold and 2-fold, respectively, whereas in myocardial fibroblasts, deletion to -40 upregulated the BNP promoter 2-fold. Of note, deleting 16 bp between -127 and -111 reduced luciferase activity 7-fold and 4-fold in ventricular and atrial myocytes, respectively, but had essentially no effect on luciferase activity in fibroblasts. Placement of sequences lying between -127 and -40 upstream from a heterologous thymidine kinase promoter resulted in reporter expression that was 7.4-fold greater than the vector alone in ventricular myocytes, approximately 2-fold greater in atrial myocytes, and equivalent to the vector alone in fibroblasts. For study of activity of the human BNP promoter in adult myocytes, either 408 or 97 bp of 5' flanking sequence coupled to the luciferase reporter gene was injected into the apex of adult male Sprague-Dawley rat hearts. After 7 days, luciferase activity in the injected myocardium was 9.8-fold higher for the longer construct (70683 +/- 14744 versus 7223 +/- 3920, n=4, P < .01), consistent with our in vitro data. These data indicate that (1) the full-length human BNP promoter is more active in ventricular versus atrial myocytes and essentially inactive in fibroblasts, (2) the distal BNP promoter contains both positive and negative regulatory elements, (3) a region of the proximal BNP promoter located between -127 and -40 confers tissue specificity, and (4) the BNP promoter is active after injection into the adult rat heart.

Animals↗
PubMed1996

Foot function in diabetic patients after partial amputation.

The function of partially amputated feet in 10 patients with diabetes mellitus was studied. First-step bilateral barefoot plantar pressure distribution and three-dimensional kinematic data were collected using a Novel EMED platform and three video cameras. Analysis of the plantar pressure data revealed a significantly greater mean peak plantar pressure in the feet with transmetatarsal amputation (TMA) than in the intact feet of the same patients. The heels of the amputated feet had significantly lower mean peak plantar pressures than all the forefoot regions. A significantly greater maximum dynamic dorsiflexion range of motion was seen in the intact compared with the TMA feet. However, no difference was noted in the static dorsiflexion range of motion between the two feet and there was, therefore, a trend for the TMA feet to use less of the available range of motion. Given the altered kinematics and elevated plantar pressures noted in this study, careful postsurgical footwear management of feet with TMA would appear to be essential if ulceration is to be prevented.

Aged↗
PubMed1996

Notch4/int-3, a mammary proto-oncogene, is an endothelial cell-specific mammalian Notch gene.

The int-3 oncogene was identified as a frequent target in Mouse Mammary Tumor Virus (MMTV)-induced mammary carcinomas and encodes the intracellular domain of a novel mouse Notch gene. To investigate the role of the int-3 proto-oncogene in mouse development and carcinogenesis, we isolated cDNA clones corresponding to the entire coding potential of the int-3 proto-oncogene. We propose to name this gene Notch4 and reserve the int-3 nomenclature for references to the oncogenic form. The deduced amino acid sequence of Notch4 contains conserved motifs found in Notch proteins; however Notch4 has fewer epidermal growth factor (EGF)-like repeats and a shorter intracellular domain than other mouse Notch homologues. Comparison of the coding potential of the int-3 gene to that of Notch4 suggests that loss of the extracellular domain of Notch4 leads to constitutive activation of this murine Notch protein. In situ hybridization revealed that Notch4 transcripts are primarily restricted to endothelial cells in embryonic and adult life. Truncated Notch4 transcripts were detected in post-meiotic male germ cells. The distinct Notch4 protein features and its restricted expression pattern suggests a specific role for Notch4 during development of vertebrate endothelium.

Amino Acid Sequence↗
PubMed1996

Immunity and morbidity in schistosomiasis japonicum infection.

Schistosomiasis japonica differs significantly from Schistosoma mansoni infection in several epidemiologic, immunologic, and operational characteristics for control. Because of numerous nonhuman hosts, transmission remains high despite aggressive case finding and treatment of human cases. Diagnosis of infection using the Kato-Katz stool technique is less sensitive and specific in this than in other species of human schistosomes, making case finding and treatment a less effective approach to control. Clinically, morbidity induced by S. japonicum appears unrelated to intensity of infection, and is more severe than that of S. mansoni in terms of liver pathology and stunting of child growth and development. Both hepatic enlargement and fibrosis appear to be reversible and preventable with aggressive treatment but several operational characteristics for control of infection due to S. japonicum make the community impact of case-finding and treatment with praziquantel less pronounced than would have been predicted by the analysis of individual cases. In the Philippines, rebound morbidity following reinfection mandates short treatment intervals between screening and treatment to have a significant impact on morbidity, while in China inapparent infection (infection not diagnosed by a single stool examination) appears to be a common cause for persistent hepatic pathology. The authors conclude that for S. japonicum, mass treatment or targeted mass treatment is a more cost-effective approach than case-finding and treatment for control.

Animals↗
PubMed1996

A systematic study of hypothermic lung preservation solutions: Euro-Collins solution.

BACKGROUND: Testing lung function after preservation is difficult because a suitable model is still lacking; thus, the effectiveness of different solutions for lung preservation has not been confirmed. This study tested the effectiveness of Euro-Collins solution alone for hypothermic preservation of rat lungs. METHODS: A living rat perfusion model was used, which allowed more than 5 hours of continuous perfusion for isolated lung function studies. Group 1 lungs (control, n = 8) were tested without preservation. In groups 2 through 6 (n = 8 lungs each), the lungs were flushed with 4 degrees C Euro-Collins solution and preserved for 4, 6, 8, 12, and 24 hours, respectively. Lung function studies were carried out after preservation. RESULTS: In groups 1 and 2, pulmonary arterial blood flow and pulmonary venous oxygen tension were higher and pulmonary resistance was lower than in the other groups. Airway pressure and resistance were lowest in group 1. Lungs in groups 5 and 6 demonstrated the worst function, but the lung tissue wet to dry ratio was higher only in group 6. CONCLUSIONS: At 4 degrees C, Euro-Collins solution can effectively preserve rat lungs for 4 hours. Six to 8 hours of preservation resulted in depressed lung function. More than 12 hours of preservation resulted in uniformly deficient lung function, rendering the lungs unsuitable for transplantation.

Airway Resistance↗
PubMed1996

[An experimental study on effects of form deprivation on development of myopia].

OBJECTIVE: The study was designed to approach the pathogenesis of myopia. METHOD: Haisaik chickens were used to establish the animal models of myopia and form deprivation method was applied. Monocular eyelids were sutured for form deprivation on the 5th day after chicken birth. RESULTS: Form deprivation leads to myopic refractive abnormality (P < 0.001). The ocular anteroposterior axis (P < 0.005), transverse and vertical diameters lengthen (P < 0.05). In the mean time, obvious pathologic changes were found. The cartilaginous cell layer of the sclera became thicker, the numbers of chondrocytes and binucleate cells were greater, and the fibrous layer of the sclera was thinner. CONCLUSION: Form deprivation is the main cause of the development of myopia.

Animals↗
PubMed1996

Ground reaction forces during locomotion in simulated microgravity.

BACKGROUND: Significant losses in bone density and mineral, primarily in the lower extremities, have been reported following exposure to weightlessness. Recent investigations suggest that mechanical influences such as bone deformation and strain rate may be critically important in stimulating new bone formation. HYPOTHESIS: It was hypothesized that velocity, cadence, and harness design would significantly affect lower limb impact forces during treadmill exercise in simulated zero-gravity (0G). METHODS: A ground-based hypogravity simulator was used to investigate which factors affect limb loading during tethered treadmill exercise. A fractional factorial design was used and 12 subjects were studied. RESULTS: The results showed that running on active and passive treadmills in the simulator with a tethering force close to the maximum comfortable level produced similar magnitudes for the peak ground reaction force. It was also found that these maximum forces were significantly lower than those obtained during overground trials, even when the speeds of locomotion in the simulator were 66% greater than those in 1G. Cadence had no effect on any of the response variables. The maximum rate of force application (DFDTmax) was similar for overground running and exercise in simulated 0G, provided the "weightless" subjects ran on a motorized treadmill. CONCLUSIONS: These findings have implications for the use of treadmill exercise as a countermeasure for hypokinetic osteoporosis. As the relationship between mechanical factors and osteogenesis becomes better understood, results from human experiments in 0G simulators will help to design in-flight exercise programs that are more closely targeted to generate appropriate mechanical stimuli.

Adult↗
PubMed1996

Prediction of blood cyclosporine concentrations in haematological patients with multidrug resistance by means of total, lean and different adipose factors dosing body weight using Bayesian and non-linear least squares methods.

In the present work, we have studied the prediction of blood cyclosporine (CsA) concentrations in haematological patients with multidrug resistance by means of total body weight, 25, 50 and 75 adipose factor dosing body weight, and lean body weight using the Bayesian method (BM) and non-linear least squares method (NLLSM) during the second course of CsA treatment. The results showed that both BM and NLLSM can minimize the prediction difference among different dosing body weight parameter types. The results also slightly favour the predictions with lean body weight.

Adult↗
PubMed1996

[Role of Leptotrombidium (L.) scutellare in transmission of human diseases].

A series of cases of hemorrhagic fever with renal syndrome (HFRS) in Shaanxi province and autumn-type tsutsugamushi disease in Jiangsu province were studied during 1988 to 1990 and 1986 to 1993 to explore the role of Leptotrombidium (L.) scutellare in transmission of these diseases. Results showed that L. (L.) scutellare is a dominant strain of mites inhabiting in rats and its seasonal fluctuation conformed to the seasonal distribution of these diseases. L. (L.) scutellare could naturally infect with HFRS virus and Rickettsia tsutsugamushi and transmit them by stinging and transovarial route. It indicated that L. (L.) scutellare could be a vector in transmission of HFRS and autumntype tsutsugamushi disease.

Animals↗
PubMed1996

The role of Leptotrombidium scutellare in the transmission of human diseases.

OBJECTIVE: To investigate the role of Leptotrombidium (L.) scutellare in the transmission of hemorrhagic fever with renal syndrome (HFRS) and tsutsugamushi disease of autumn-type. MATERIALS AND METHODS: Four criteria were used to ascertain this mite as transmitting vector of disease: (1) epidemiological evidence; (2) natural infection of pathogen; (3) ability to transmit pathogen via biting; (4) ability to transfer pathogen via transovarian route. RESULTS: The results indicated that L. scutellare was the dominant species of chigger mite on rats. Its seasonal distribution was correlated with the incidence of these two diseases. This mite could be naturally infected by HFRS virus (HFRSV) and Rickettsia tsutsugamushi (Rt) and the mite could transmit HFRSV and Rt to vertebrates by biting and to its offspring via transovarian transmission. CONCLUSIONS: These results have proved that L. scutellare can be a transmitting vector of HFRS and tsutsugamushi disease of autumn-type.

Animals↗
PubMed1996

[Construction of Chinese genomic cosmid library].

A Chinese genomic library has been constructed using SuperCos1 cosmid vector. 6.09 x 10(5) clones were obtained with an everage insert size of 40 kb ranging from 32 to 45 kb, which cover approximately 8.12 fold human genomic DNA. DNA pools prepared from the total library were screened with 6 known markers distributed on different chromosomes, which all were tested positive.

Asian People↗