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Biomedical subjects

J Wu

Publications and source records attributed to J Wu.

At least 1,441 records · Page 80Linked to original sources
PubMed1991

Transforming growth factor-beta (TGF-beta) isoforms in rat liver regeneration: messenger RNA expression and activation of latent TGF-beta.

Expression of transforming growth factor-beta s (TGF-beta s) 1-3 was studied in normal liver and during liver regeneration after partial hepatectomy in the rat to determine whether each of these isoforms might be involved in hepatocyte growth in vivo. Expression of the mRNAs for all three TGF-beta isoforms increases in the regenerating liver. In addition, the levels of expression of the mRNAs for several extracellular matrix proteins, including fibronectin, vitronectin, laminin, and collagen, also increase in the regenerating liver. Immunohistochemical staining analysis shows a similar distribution of all three TGF-beta s in normal and regenerating liver; however, in both tissues, the level of expression of TGF-beta 1 is 8- to 10-fold higher than that of TGF-beta 2 as determined by sandwich enzyme-linked immunosorbent assay. Expression of all three TGF-beta mRNAs is restricted to liver nonparenchymal cells. Although hepatocytes from normal and regenerating livers do not synthesize TGF-beta, they are sensitive to inhibition of growth by all three TGF-beta isoforms. Hepatocytes from regenerating livers are capable of activating latent TGF-beta 1 complexes in vitro, whereas normal hepatocytes are not. The different TGF-beta isoforms may function in an inhibitory paracrine mechanism that is activated during liver regeneration and may also regulate the synthesis of extracellular matrix components in the regenerating liver.

Animals↗
PubMed1991

Blood pressure lowering in elderly subjects: a double-blind crossover study of omega-3 and omega-6 fatty acids.

In 46 elderly (aged greater than or equal to 60 y) hypertensive subjects with entry systolic blood pressure (SBP) greater than or equal to 160 or diastolic blood pressure (DBP) greater than or equal to 90 mm Hg, our specific aim in a randomized, double-blind, crossover study (two 8-wk treatment periods separated by a 3-wk washout) was to compare blood pressure-lowering effects of 9 g fish oil/d [omega-3 (n-3) fatty acid] vs 9 g corn oil/d [omega-6 (n-6) fatty acid]. After a 4-wk baseline period, 22 subjects were randomly assigned to receive fish oil and 24 to receive corn oil. For both 8-wk treatments there were no between-group differences in the change in blood pressure. There was a treatment difference for standing DBP when baseline values were compared with those after treatment 2; DBP decreased by 5.1 mm Hg in the fish-oil group vs 0.72 mm Hg in the corn-oil group (P = 0.024). Within groups during the first treatment, both fish oil and corn oil lowered all four blood pressure measures (P less than 0.05); blood pressures were not further lowered during the second treatment compared with the washout period. There were no significant between-group differences in laboratory safety tests or categorical side effects. Fish oil lowered triglycerides by 0.47 mmol/L (P less than 0.001). In elderly subjects, diet plus both omega-3 and omega-6 supplements (9 g/d) safely and effectively lower SBP and DBP.

Aged↗
PubMed1991

Photosynthetic and photorespiratory characteristics of flaveria species.

The genus Flaveria shows evidence of evolution in the mechanism of photosynthesis as its 21 species include C(3), C(3)-C(4), C(4)-like, and C(4) plants. In this study, several physiological and biochemical parameters of photosynthesis and photorespiration were measured in 18 Flaveria species representing all the photosynthetic types. The 10 species classified as C(3)-C(4) intermediates showed an inverse continuum in level of photorespiration and development of the C(4) syndrome. This ranges from F. sonorensis with relatively high apparent photorespiration and lacking C(4) photosynthesis to F. Among the intermediates, the photosynthetic CO(2) compensation points at 30 degrees C and 1150 micromoles quanta per square meter per second varied from 9 to 29 microbars. The values for the three C(4)-like species varied from 3 to 6 microbars, similar to those measured for the C(4) species. The activities of the photorespiratory enzymes glycolate oxidase, hydroxypyruvate reductase, and serine hydroxymethyltransferase decreased progressively from C(3) to C(3)-C(4) to C(4)-like and C(4) species. On the other hand, most intermediates had higher levels of phosphenolpyruvate carboxylase and NADP-malic enzyme than C(3) species, but generally lower activities compared to C(4)-like and C(4) species. The levels of these C(4) enzymes are correlated with the degree of C(4) photosynthesis, based on the initial products of photosynthesis. Another indication of development of the C(4) syndrome in C(3)-C(4)Flaveria species was their intermediate chlorophyll a/b ratios. The chlorophyll a/b ratios of the various Flaveria species are highly correlated with the degree of C(4) photosynthesis suggesting that the photochemical machinery is progressively altered during evolution in order to meet the specific energy requirements for operating the C(4) pathway. In the progression from C(3) to C(4) species in Flaveria, the CO(2) compensation point decreased more rapidly than did the decrease in O(2) inhibition of photosynthesis or the increase in the degree of C(4) photosynthesis. These results suggest that the reduction in photorespiration during evolution occurred initially by refixation of photorespired CO(2) and prior to substantive reduction in O(2) inhibition and development of the C(4) syndrome. However, further reduction in O(2) inhibition in some intermediates and C(4)-like species is considered primarily due to the development of the C(4) syndrome. Thus, the evolution of C(3)-C(4) intermediate photosynthesis likely occurred in response to environmental conditions which limit the intercellular CO(2) concentration first via refixation of photorespired CO(2), followed by development of the C(4) syndrome.

Journal Article↗
PubMed1991

The ArsR protein is a trans-acting regulatory protein.

The arsR gene encodes the regulatory protein of the plasmid-encoded arsenical resistance operon. A series of in-frame fusions was constructed between the C-terminally truncated arsR gene and the coding region for the mature form of beta-lactamase (blaM). Fusions containing most of the arsR gene were still inducible by arsenicals. Fusions containing less than 102 residues of the 117-residue ArsR protein were constitutive. When a wild-type arsR gene was placed in trans, the constitutive constructs were again inducible. The results demonstrate that the ArsR protein is a trans-acting regulatory protein which controls its own expression.

Adenosine Triphosphatases↗
PubMed1991

Two divergently transcribed genes, soxR and soxS, control a superoxide response regulon of Escherichia coli.

soxR governs a superoxide response regulon that contains the genes for endonuclease IV, Mn2(+)-superoxide dismutase, and glucose 6-phosphate dehydrogenase. The soxR gene encodes a 17-kDa protein; some mutations of this gene cause constitutive overexpression of the regulon. Induction by paraquat (methyl viologen) requires both soxR and a new gene, soxS. soxS is adjacent to soxR, it encodes a 13-kDa protein, and it is required for paraquat resistance. These functions were revealed by studies in which the sequence of the 1.1-kb soxR-soxS region was determined, the 5' ends of the mRNAs were mapped, and complementation tests were performed with soxRS plasmids containing deletions of known sequence. The two genes are divergently transcribed, and the transcripts overlap. The soxS promoter is within the 85-nucleotide intergenic region, whereas the soxR promoter is within soxS. soxS mRNA increases after induction. Both protein products have possible DNA-binding (helix-turn-helix) domains. SoxR contains four cysteines (CX2CXCX5C) that might be part of a sensor region. SoxS shows 17 to 31% homology to the C-terminal portions of members of the AraC family of positive regulators.

Amino Acid Sequence↗
PubMed1991

The cytoprotective effects of bilirubin and biliverdin on rat hepatocytes and human erythrocytes and the impact of albumin.

The hypothesis that unconjugated bilirubin and biliverdin are cytoprotective antioxidants has been examined for the first time in systems containing cells. In primary rat hepatocytes exposed to xanthine oxidase and hypoxanthine, bilirubin (0-60 microM) failed to prolong cell survival. In contrast, biliverdin (20-100 microM) markedly delayed hepatocyte necrosis in a concentration-dependent manner. When 0.3 mM of albumin was present, bilirubin (0-50 microM) became protective of hepatocytes, while biliverdin was less dramatically enhanced in its cytoprotective effect. In human erythrocytes exposed to peroxyl radicals, bilirubin and biliverdin inhibited 50% cell lysis at lower concentrations than Trolox and ascorbate, respectively. Albumin alone appeared less cytoprotective in red cells than in hepatocytes, but its presence enhanced the effects of both pigments on erythrocytes. Of probable physiologic relevance, bilirubin with albumin present or biliverdin alone protected hepatocytes substantially (and to a lesser extent red cells) at the normal blood levels of bilirubin (3.4-26 microM). Moreover, the fact that the pigments are cytoprotective at higher bilirubin levels (e.g., 50-100 microM) tempts the speculation that they may be circulating cytoprotectors of overlooked importance in jaundice.

Animals↗
PubMed1991

Molecular basis of an autoantibody-associated restriction fragment length polymorphism that confers susceptibility to autoimmune diseases.

Recently, combined serological and molecular studies of autoantibodies have revealed that these antibodies play an important role in the normal function of the immune system and in the development of the B cell repertoire. Accordingly, we hypothesized that a homozygous deletion of a critical autoantibody-associated Ig variable (V) gene may alter the immune system and thus predispose the host to autoimmune disorders. Initial experiments revealed several restriction fragment length polymorphisms (RFLP) of the Humhv3005 gene, that is likely to encode heavy chains of rheumatoid factors, and the closely related 1.9III gene. By probing EcoR1-digested DNA with the Humhv3005/P1 probe, we found that one of the four major hybridizing bands was missing in approximately 20% of patients with either rheumatoid arthritis or systemic lupus erythematosus, but only 2% of normal subjects. To delineate the genetic basis of this polymorphism, we have now employed the PCR to amplify and analyze hv3005, 1.9III, and homologous genes in individuals with characteristic RFLP genotypes. Our results indicate that the human Vh gene repertoire contains several hv3005- and 1.9III-like genes, and that a complete deletion of the hv3005-like genes is relatively restricted to a subset of autoimmune patients. These findings provide initial evidence for deletion of developmentally regulated autoreactive V genes in autoimmune diseases.

Amino Acid Sequence↗
PubMed1991

Positron-emission tomographic studies of the relationship of cerebral glucose metabolism and the magnitude of anxiety and hostility experienced during dreaming and waking.

The authors examined correlations between anxiety and hostility levels experienced during wakefulness, rapid eye movement (REM) dreaming, nonrapid eye movement (NREM) mentation (as assessed by the Gottschalk-Gleser Content Analysis Scales), and cerebral glucose metabolism as measured by positron-emission tomography (PET) in 30 normal volunteers. Different cerebral areas showed significant correlations for anxiety and six anxiety subscales, hostility outward, hostility inward, and ambivalent hostility, as assessed by the patterns of significant positive or negative correlations found with the activation of these emotions. Significant correlations occurred more often in waking and REM dreaming subjects than NREM subjects and were more common in the frontal, parietal, and temporal lobes than in the occipital lobe. Correlations tended to be positive for waking subjects and negative for REM subjects.

Adult↗
PubMed1991

Research note: utility of the thiobarbituric acid test in the determination of the quality of fats and oils in feeds.

The TBA test is a rapid and simple method for determining the extent that a fat has degraded to non-metabolizable aldehydes, such as malondialdehyde. A fat that has a high peroxide number or high value in the TBA test would not be suitable for use in feeds because it would contain a high peroxide or aldehyde content. The digestibility of corn oil, poultry fat, and a commercial animal-vegetable blend incorporated into a basal diet were 91.0, 88.3, and 69.7% with metabolizable energy of 9.664, 9.020, and 5.961 kcal/g and transit times in the digestive tract of 173, 167, and 140 min, respectively. The commercial blend had the highest value in the TBA test and also had the highest level of lipid hydroperoxides and the lowest content of total fatty acids. In contrast, the corn oil had the lowest value in the TBA test, the lowest peroxide number, and the highest content of total fatty acids. The data suggest that the TBA test may be useful as an indication of the quality of fats and oils for use in feeds.

Animal Feed↗
PubMed1991

[Application of polymerase chain reaction in amplification of human cytomegalovirus B gene code region].

A nucleic acid amplification procedure, the polymerase chain reaction (PCR), has been used to amplify the human cytomegalovirus (HCMV) B gene code region, and its glycoprotein 52 kd antigenic domain. The primers used in the PCR assay were based on a conserved region of the HCMV B gene sequence. By using primer 1 (5'-AAAGAATTCATGGAATCCAGGATCTG-3', upstream nucleotides 157 to 2877), primer 2 (5'-AAAGAATTCATGAACGTGAAGGAATCG-3', upstream nucleotides 1846 to 2877), and primer 4(5'-ATAAAGCTTAATCAGACGTTCTCTTCTTC-3', downstream nucleotides 157 to 2877 and 1846 to 2877), the HCMV B gene code region sequence and its glycoprotein 52 kd antigenic domain sequence were amplified from the recombinant plasmid pBH1 DNA containing the HCMV B gene. Amplification cycles consisted of denaturation at 92 degrees C for 1 min, annealing at 55 degrees C for 1 min, and extension at 72 degrees C for 1.5 min. The cycles were carried out 30 times in three different water baths, respectively. After the last extension, 10 microliter of each reaction mixture was removed and subjected to electrophoresis on 1.2% agarose gel. Ten microgram of PCR products were obtained from 0.2 microgram of template DNA after the 30 times cycles, and were enough for being used in the restriction site analysis and the construction of clones.

Base Sequence↗
PubMed1991

[Studies on the quality of fructus Cnidii--comparison of antibacterial action].

Comparative studies on antibacterial and antifungal action of the fruits of C. monnieri from four habitats and two other species of Cnidium showed they had inhibitory potency to some bacterial and fungi in vitro. C. monnieri and C. salium were more effective than C. dahuricum in antibacterial activities. C. monnieri had higher antifungal effect than C. salium and C. dahuricum.

Bacteria↗
PubMed1991

[The value of spectral mapping of electrocardiograms with Fourier transform in detecting late potentials].

The results of spectral mapping of the electrocardiogram (ECG) with Fourier transform of multi-segments (Blackman-Harris window, size 80 ms, 40 segments, time shift 2 ms) were studied in 7 patients with recurrent sustained ventricular tachycardia (VT, group 1), 16 patients with a history of myocardial infarction without VT (group 2) and 30 healthy volunteers (group 3). The 3-dimensional spectral plots in group 1 were characterized by the discrete high amplitude multi-peaks and increased high-frequency components at the end of QRS complex and early ST segment. The spectral-peak amplitude in group 1 (13.14 +/- 6.54 db) was significantly higher than that in group 2 and group 3 (P less than 0.05 and P less than 0.01), and the spectral-peak amplitude in group 2 (6.25 +/- 3.19 db) also higher than that in group 3 (4.30 +/- 2.00 db, P less than 0.05). The frequency spectra of late potentials mainly ranged from 40 to 100 Hz. The spectral peaks due to noises were present in all segments and irrespective of segment choice. The preliminary observation suggested that multi-segments spectral mapping of the ECG with Fourier transform offers a new analytic method for better identification of patients prone to sustained ventricular tachycardia.

Adult↗
PubMed1991

Recombinant human granulocyte macrophage colony-stimulating factor (rhGM-CSF) induces human macrophage production of transforming growth factor-alpha.

Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) is known as an inducer of proliferation and functional activation of myeloid cells. This study was carried out to characterize the effect of purified recombinant human GM-CSF (rhGM-CSF) on induction of TGF-alpha in macrophages. Using Northern blot analysis and immunoassays, we show here that rhGM-CSF markedly stimulates production of TGF-alpha messenger RNA and protein in normal tonsil macrophages. The findings are consistent with macrophages being a normal inducible source of TGF-alpha which may be an important mediator of various activities of GM-CSF both in hematopoietic and non-hematopoietic cells.

Animals↗