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Biomedical subjects

X D Wang

Publications and source records attributed to X D Wang.

At least 127 records · Page 7Linked to original sources
PubMed1991

A factor that positively regulates cell division by activating transcription of the major cluster of essential cell division genes of Escherichia coli.

Cell division in Escherichia coli requires the products of the ftsQ, ftsA and ftsZ genes. It is not known how the cell regulates the cellular concentrations of these essential elements of the division system. We describe here a factor that activates cell division by specifically increasing transcription from one of the two promoters that lie immediately upstream of the ftsQAZ gene cluster. The trans-acting factor is the product of the sdiA gene, which was isolated on the basis of its ability to suppress the division inhibitory effect of the MinC/MinD division inhibitor. In addition, the sdiA gene product suppressed the action of other chromosomally encoded division inhibitors, induced minicell formation in wild type cells, and restored division activity to an ftsZ temperature-sensitive mutant grown under nonpermissive conditions. All of these properties were explained by the ability of the sdiA gene product specifically to increase transcription of the ftsQAZ gene cluster, resulting in an increase in cellular concentration of the FtsZ protein. The sdiA gene product is the first factor thus far identified that specifically regulates expression of this key group of cell division genes.

Amino Acid Sequence↗
PubMed1991

Improvement of the effects of intrasplenic transplantation of hepatocytes after 90% hepatectomy in the rat by cotransplantation with pancreatic islets.

Acute liver failure is associated with high mortality. Whether support with transplanted hepatocytes improves the outcome is not established. We studied the potential beneficial effects of intrasplenic transplantation of hepatocytes in conjunction with islets of Langerhans on 90% hepatectomy-induced acute liver failure in rats. We found that all control rats died within 48 hr following 90% hepatectomy. In contrast, the mortality decreased significantly in rats transplanted with 10(7) hepatocytes into the spleen parenchyma at 1-3 days prior to 90% subtotal hepatectomy, whereas no significant reduction in mortality was seen in rats transplanted with hepatocytes immediately after the operation. However, cotransplantation of hepatocytes and 400 isolated pancreatic islets into the spleen reduced mortality when performed immediately after the 90% hepatectomy. Therefore, hepatocyte transplantation reduces mortality after 90% hepatectomy only if performed prior to the hepatectomy. However, transplantation of hepatocytes in conjunction with pancreatic islets reduces mortality when performed at the same time as 90% hepatectomy. Hence, the combined transplantation of hepatocytes and islets might offer support after liver failure.

Alkaline Phosphatase↗
PubMed1991

Application of pyridostigmine in evaluation of growth hormone reserves in children and adolescents.

There is evidence that the cholinergic system positively modulates growth hormone (GH) secretion. In the present study, we observed the effects of cholinergic enhancement by pyridostigmine (PD), a cholinesterases inhibitor, on GH release in both normal (n = 13) and GH deficient children and adolescents (n = 10). Responses of GH to insulin hypoglycemia (Ins) were also observed. In the normal subjects, PD-induced serum GH peak level was significantly higher than that induced by Ins (P less than 0.01), while the GH level in the patients with pituitary dwarfism showed no increase in both tests. This study indicates that PD test may be considered a sensitive dynamic test in evaluating pituitary function of GH secretion in children and adolescents.

Adolescent↗
PubMed1991

[Molecular recognition between glycophorin A and Plasmodium falciparum merozoites].

By using purified human erythrocyte membrane glycophorin A (GPA) and glycopeptide of GPA, antibodies against GPA and against GPA-glycopeptide, and SPA-colloidal gold, Plasmodium falciparum FCC-1/HN merozoites were immunolabeled. The labeled samples were observed under transmission electron microscope (TEM). The TEM pictures showed that colloidal gold pellets were distributed over all of the merozoite surface. This is the first report on the direct experimental evidence of molecular recognition and combination between GPA (or glycopeptide of GPA) and Plasmodium falciparum merozoites. The results strongly support the hypothesis that GPA is involved as a recognized receptor on erythrocytes for Plasmodium falciparum and the glycopeptide domain of GPA is the receptor site for Plasmodium falciparum.

Animals↗
PubMed1990

Human urate oxidase gene: cloning and partial sequence analysis reveal a stop codon within the fifth exon.

Using the cDNA and selected genomic probes of rat urate oxidase, we have screened the human genomic library and isolated seven clones; one clone (clone 13) contained exonic regions which correspond to the exons 5, 6, and 7 of rat urate oxidase gene. The nucleotide sequence was determined for these three exons and exon/intron junctions, and compared with the sequence from the rat gene. A mutation resulting in a stop codon TGA was found in the fifth exon of the human urate oxidase gene. Sequence analysis of the polymerase chain reaction amplified DNA, corresponding to the fifth exon of urate oxidase from DNA samples from four different individuals, confirmed the same TGA stop codon in all. This single stop codon mutation and/or other mutation(s) in this gene may be responsible for the lack of urate oxidase activity in the human.

Amino Acid Sequence↗
PubMed1990

[Effects of ketotifen on rabbit platelet aggregation and platelet activating factor formation from rat neutrophils].

The effects of ketotifen (Ket) on rabbit platelet aggregation induced by platelet activating factor (PAF), ADP and arachidonic acid (AA) and PAF formation from A-23187-stimulated rat neutrophils in vitro were studied. PAF (15-100 pmol/L) induced rabbit platelet aggregations, with an EC50 of 33 pmol/L. Ket shifted the PAF dose-dependent platelet aggregation curve to the right in a parallel fashion with no depression of the maximal response and reversed the secondary aggregation phase, suggesting that Ket had competitive antagonistic activity against PAF-induced platelet aggregation. It also showed inhibitory effects on platelet aggregations induced by ADP 10 mumol/L and AA 50 mumol/L, the IC50 were 94.5 and 143.5 mumol/L respectively. However, it failed to influence PAF formation from rat neutrophils stimulated by A-23187 2.5 mumol/L in vitro. The inhibitory effects of Ket on platelet activation, particularly PAF-induced platelet aggregation, may contribute to its anti-asthmatic properties.

Animals↗
PubMed1990

Chinese patients with transient ischemic attacks.

In 123 cases of transient ischemic attacks, 72 were followed up for 22 years. The percentage of complete stroke was 46.5% and the fatality rate 47.9%. Causes of death, survival rate by life table, limitation of indication of neurovascular surgical operation and rehabilitation of survived patients were studied. The causes of death were mainly cerebral strokes. The long-term follow-up showed that the range for neurovascular surgical operation was limited to only 17.9%. The 95% confidence interval of the 20-year survival rate was 17.7-53.6%. Ninety-four, 48 and 44 cases were examined by B-mode Doppler tomography, cerebral CT scanning and echocardiography, respectively.

Adult↗
PubMed1989

Structural parts involved in activation and inactivation of the sodium channel.

Structure-function relationships of the sodium channel expressed in Xenopus oocytes have been investigated by the combined use of site-directed mutagenesis and patch-clamp recording. This study provides evidence that the positive charges in segment S4 are involved in the voltage-sensing mechanism for activation of the channel and that the region between repeats III and IV is important for its inactivation.

Action Potentials↗
PubMed1989

The nucleotide sequence of a full length cDNA clone encoding rat liver urate oxidase.

Recently we reported the sequence of a cDNA clone (pUOX-1), isolated from a lambda gt11 cDNA library, which encoded for rat liver urate oxidase (EC 1.7.3.3), but this clone lacked the nucleotide sequences encoding the N-terminal region for this enzyme. Using the cDNA insert from the pUOX-1 clone as a probe, we have now isolated a full length cDNA clone, pUOX-2, from a lambda gt10 library by plaque hybridization. Nucleotide sequence analysis of the pUOX-2 clone showed that it has 1379 base pairs with an open reading frame coding for 303 amino acid residues corresponding to a molecular mass of 34,931 daltons. In addition to the open reading frame the pUOX-2 contains 439 bp of 3'-untranslated and 41 bp of 5'-untranslated sequences. The consensus polyadenylation signal AATAAA precedes a stretch of poly(A)+ residues at the 3' end.

Amino Acid Sequence↗
PubMed1989

Structural characterization of the bovine CYP17 (17 alpha-hydroxylase) gene.

The complete exonic and partial intronic sequence of the bovine CYP17 (P45017 alpha) gene has been determined. The gene contains eight exons with exon/intron boundaries which are identical to those determined previously for the human CYP17 gene. The site of initiation of transcription of this gene is located within a 6-base sequence 52 bp from the initiation of translation. Considerable sequence homology (58.7%) is found when approximately 500 bp of the 5'-flanking sequences of the bovine and human CYP17 genes are compared. A computer-based search of this region of bovine CYP17 for consensus sequences associated with binding of transcription factors (i.e., GR, PR, CREB/ATF, AP1, AP2, AP3, AP4, AP5, OTF, CTF/NF1, SP1) shows only the consensus CREB/ATF sequence TGACGT which is also found to be at approximately the same position in the human CYP17 gene. In bovine adrenal cortex, transcription of the CYP17 gene is regulated by the peptide hormone adrenocorticotropin via cAMP. Whether the consensus CREB/ATF sequence is associated with the cAMP-mediated transcription of the CYP17 gene remains to be elucidated.

Adrenal Cortex↗
PubMed1989

Hydroxyl radical "footprinting" of RNA: application to pre-mRNA splicing complexes.

We present an adaptation of the hydroxyl radical DNA "footprinting" technique that permits high-resolution mapping of protected regions of RNA. Hydroxyl radical cleaves RNA independently of base sequence and secondary structure of the RNAs examined and allows resolution of protected regions at the single nucleotide level. By using this technique, we show that several regions of the 3' splice site of mRNA precursors are protected during the formation of splicing-specific ribonucleoprotein complexes in an in vitro splicing system. These regions include the 3' intron/exon junction and a portion of the adjacent exon, the polypyrimidine tract, and the site of branch formation. These protections appear to be due to splicing specific complexes since their formation is sensitive to point mutations at crucial residues and requires ATP and incubation. The formation of these protected regions is independent of the presence of a 5' splice site.

Animals↗
PubMed1989

Study on atherosclerosis of extracranial portion of carotid artery system in healthy persons.

This paper reports the real time B-mode Doppler scanning findings of the extracranial portion of carotid arterial system (CAS) in 182 healthy persons (119 males and 63 females). The results showed that the diameter of the lumen of common carotid artery (CCA), bifurcation of common carotid artery (BCCA) and internal carotid artery (ICA) was larger in males than in females; there was no relationship between the diameter of the lumen of CCA, BCCA and ICA and body height; the diameter of lumen of CCA increased with age; 29 cases of atherosclerosis of the arterial wall (11 lesions with thickening of intima, 16 with hard plaque, one with soft plaque and 5 with stenosis) were observed; and the incidence of positive findings of atherosclerotic lesion of extracranial portion of CAS in the 40-49 age group and 50-59 age group was only 4.2% and 4.8% respectively, while the incidence in those aged over 60 increased markedly to 26.5-41.7%. These suggested that incidence of atherosclerosis in extracranial portion of CAS was not low in healthy persons without any evidence of stroke. As atheromatous lesions may be related to the consequent onset of stroke in the future, follow-up study and repeated Doppler scanning are necessary so as to observe the relationship between the location and severity of the lesion and the occurrence of cerebrovasculor disease. They may be helpful in determining the indication for carotid artery operation and also play a role in the prevention and treatment of CVD.

Adult↗
PubMed1989

[A further study and discussion on mirror writing and the development of the Chinese written language].

Mirror image writing was done in 72 preschool children, 40 school children, 40 normal adults and 37 stroke patients with or without aphasia. The results showed that total mirror image writing was demonstrated in only one case and partial mirror image writing in 62 (32.8%). The cases of mirror image writing with the left hand in the preschool children, school children, normal adults and patients with stroke were found in 45.8%, 10.0%, 2.5% and 24.3% respectively. The relationship between mirror image writing and left or right hand disorientation and that between mirror image writing and visual aid were observed.

Adult↗
PubMed1988

Comparative study of affective disorders in three Asian countries. I. Differences in diagnostic classification.

A study aimed at the standardization of symptom evaluation of patients with depression was carried out as the first step in an extensive collaborative study on affective disorders between centers in Nagasaki, Shanghai and Seoul. This study was initiated in order to clarify the factors affecting the low reported prevalence rates of depressive disorders in Asia. No significant difference in evaluation of psychiatric symptoms was observed between the 3 centers. Nevertheless, the diagnoses given by ICD-9 showed very interesting differences. For any given case, Nagasaki tended to make a diagnosis of an affective psychosis depression, while Shanghai made a diagnosis of neurotic disorder. No significant tendency was observed in the Seoul center. These findings are discussed in terms of their importance for future international collaborative studies.

Affective Disorders, Psychotic↗
PubMed1988

Who seeks mental health care in China? Diagnoses of Chinese outpatients according to DSM-III criteria and the Chinese classification system.

The authors gave DSM-III diagnoses to 116 Chinese psychiatric outpatients in Shanghai and compared them with the diagnoses of the same patients made by a Chinese psychiatrist according to Chinese criteria. Affective disorders were the most common DSM-III diagnoses, accounting for 26.7% of the sample. A full range of psychopathology, including schizophrenia, organic mental disorders, adjustment disorders, anxiety disorders, and paranoid disorders, was seen. Some consistent differences in diagnosis by Chinese and Western standards, especially in the area of major depression, were found. The authors discuss the implications for interpreting psychiatric studies from China and for future cross-cultural research comparing U.S. and Chinese diagnoses.

Adult↗
PubMed1988

The gut: a central organ after surgical stress.

The intestinal tract plays a central role in the protein catabolic response after injury and infection. The mucosa utilizes glutamine and thus spares glucose--presumably sparing this essential fuel source for tissues with an obligate glucose requirement. With inadequate nutritional support or prolonged stress, glutamine levels decrease in both the plasma and the tissue pools, which suggests that glutamine deficiency occurs. This is associated in time with atrophy of the gastrointestinal mucosa. This provision of dietary glutamine results in correction of the abnormally low glutamine concentrations and increased cellularity of the gut mucosa. The derangements in the intestinal mucosa associated with starvation, injury, infection, immunosuppression, chemotherapy, lack of enteral feedings, and other stresses are associated with a breakdown in the barrier function of the gut. Both bacteria and their toxins may enter the host from the intestinal lumen. Through interaction with the reticuloendothelial system, cytokines are produced, which stimulate the pituitary-adrenal axis and thus contribute to the stress response. The elaboration of glucocorticoids facilitates proteolysis, thus increasing glutamine release from skeletal muscle for gut repair. Although this homeostatic mechanism appears to aid mucosal repair and support immunologic responses, severe injury or prolonged glutamine deficits do not adequately support intestinal recovery and allow this cycle to become self-perpetuating (Fig 3). Adequate enteral feedings initiated early in the course of a disease appear to maintain adequate gut barrier function. In the frequent circumstance when feeding by this route is inadequate or impossible, glutamine-containing parenteral feedings offer an appropriate alternative therapy for bowel and immunologic support. Glutamine-containing parenteral feedings are associated with increased mucosal cellularity and improved survival after gut injury. Specific hormones also stimulate mucosal growth, and it is anticipated that a combination of hormones and specific nutrients will provide optimal support of the gut mucosa in the severely ill patient.

Animals↗