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Biomedical subjects

W Dai

Publications and source records attributed to W Dai.

104 records · Page 6Linked to original sources
PubMed1992

Anatomical mapping of functional activation in stereotactic coordinate space.

Numerous applications have been reported for the stereotactic mapping of focal changes in cerebral blood flow during sensory and cognitive activation as measured with positron emission tomography (PET) subtraction images. Since these images lack significant anatomical information, analysis of these kinds of data has been restricted to an automated search for peaks in the PET subtraction dataset and localization of the peak coordinates within a standardized stereotactic atlas. This method is designed to identify isolated foci with dimensions smaller than the image resolution. Details of activation patterns that may extend over finite distances, following the underlying anatomical structures, will not be apparent. We describe the combined mapping into stereotactic coordinate space of magnetic resonance imaging (MRI) and PET information from each of a set of subjects such that the major features of the activation pattern, particularly extended tracts of increased blood flow, can be immediately assessed within their true anatomical context as opposed to that presumed using a standard atlas alone. Near areas of high anatomical variability, e.g., central sulcus, or of sharp curvature, e.g., frontal and temporal poles, this information can be essential to the localization of a focus to the correct gyrus or for the rejection of extracerebral peaks. It also allows for the removal from further analysis of data from cognitively-normal subjects with abnormal anatomy such as enlarged ventricles. In patients with neuropathology, e.g., Alzheimer's disease, arteriovenous malformation, stroke, or neoplasm, the use of correlated MRI is mandatory for correct localization of functional activation.

Adult↗
PubMed1992

[Distribution of silver staining-nucleolar organizer regions (Ag-NOR) in nasopharyngeal carcinoma].

Using silver staining technique, nucleolar organizer regions (Ag-NOR) were studied in paraffin section of 20 nasopharyngeal carcinoma (NPC), 10 chronic nasopharyngitis and 10 benign hyperplasia of mucosal epithelial. The results suggested that Ag-NOR showed clear black dots in nuclei. Malignancy lesion possessed much more Ag-NOR per nucleus than the other benign. In NPC a mean value of 5.95 (s1.78) Ag-NOR per nucleus was found, chronic nasopharyngitis was 1.31 (s0.14) and benign hyperplasia of mucosal epithelial was 2.16 (s0.34). This content of Ag-NOR per nucleus has a distinct difference in between NPC and benign lesion. We thought that the Ag-NOR technique would have an important value for differential diagnosis of benign and malignancy in nasopharyngeal lesion.

Adolescent↗
PubMed1991

Analysis of interferon-gamma resistant mutants that are possibly defective in their signaling mechanism.

Our previous observations indicated that mutants partially resistant to IFN-gamma cytotoxicity were defective in the induction of indoleamine 2,3-dioxygenase, (IDO). Two mutants highly resistant to IFN-gamma were isolated following a second round of mutagenesis. The resistance to IFN-gamma was inversely correlated with the inducibility of IDO in these mutants. Moreover, several other IFN-gamma responsive genes, including those encoding 2-5A synthetase, GTP cyclohydrolase and HLA-DR alpha, were also differentially altered in their expression upon INF-gamma treatment. IFN-gamma receptor gene expression was not changed nor was the binding of the receptor to IFN-gamma. Southern blot analysis failed to reveal any significant abnormality in the IDO gene structure in these mutants. We therefore suggest that these mutants are defective in the IFN-gamma signaling pathway and will be useful in further analysis of the biochemical mechanism of IFN-gamma activated gene expression in target cells.

Blotting, Northern↗
PubMed1990

Regulation of indoleamine 2,3-dioxygenase gene expression in human fibroblasts by interferon-gamma. Upstream control region discriminates between interferon-gamma and interferon-alpha.

The interferon (IFN)-gamma-mediated induction of indoleamine 2,3-dioxygenase (IDO) enzyme, which converts tryptophan into N-formylkynurenine, has been implicated in the inhibition of intracellular pathogens, e.g. Toxoplasma gondii and Chlamydia psittaci, and in the antiproliferative effect of IFN-gamma on tumor cells. The IDO activity is induced strongly in many cell types by IFN-gamma but rather poorly by IFN-alpha or -beta. A genomic DNA clone containing part of the transcribed region of the IDO gene and approximately 13 kilobases (kb) of the 5'-upstream DNA sequence was isolated and analyzed. An approximately 1.4-kb fragment of this clone, containing 329 nucleotides of the transcribed sequence and approximately 1.1 kb of the 5'-upstream sequence, when ligated to chloramphenicol acetyltransferase (CAT) structural gene made its expression inducible by IFN-gamma, but this construct responded poorly, if at all, to IFN-alpha 2. Deletion constructs derived from this plasmid narrowed down the IFN-gamma-responsive region to a 151-nucleotide segment (-495/-344) which also contained a 14-nucleotide sequence (GGTTTCAGTTTTCC) highly homologous to the IFN(alpha)-stimulated response element (ISRE) that has been found so far in all cellular genes inducible with IFN-alpha or -beta. Expression of CAT activity was stimulated by IFN-gamma more effectively than by IFN-alpha 2 when a 155-nucleotide fragment (-495/-340) containing the 151-nucleotide segment required for IFN-gamma response was inserted before herpes simplex virus thymidine kinase promoter linked to CAT structural gene. The results indicate that despite the presence of an ISRE, the control region of the IDO gene can distinguish between IFN-gamma and IFN-alpha. This may account for the differential activation of IDO gene expression by IFN-gamma as against IFN-alpha or -beta in intact cells, and suggests that the response of ISRE to IFN-alpha or -beta may be governed by other features in the upstream control region of this gene.

Base Sequence↗
PubMed1990

Molecular cloning, sequencing and expression of human interferon-gamma-inducible indoleamine 2,3-dioxygenase cDNA.

The antiproliferative action of human interferon (HuIFN)-gamma on human cells and the inhibition of intracellular pathogens, e.g. Toxoplasma gondii and Chlamydia psittaci, is at least in part due to an induction of indoleamine 2,3-dioxygenase (IDO) enzyme which degrades tryptophan, an essential amino acid. A cDNA clone (called C42) was isolated from a cDNA library made from poly(A)+ RNA obtained from HuIFN-gamma-treated human fibroblasts. Its nucleotide sequence revealed an open reading frame coding for a polypeptide of 403 amino acids, but no homology with any known gene in GenBank database was found. Evidence was obtained indicating that this cDNA codes for IDO: (i) Hybrid selected C42 specific poly(A)+ RNA from IFN-gamma-treated human cells coded for a polypeptide in vitro of approximately 42 kD (reported size of IDO, approximately 40 kD) which was immunoprecipitated by monoclonal anti-IDO antibody but not by a control antibody; and (ii) transfection of human fibroblasts with an expression plasmid containing C42 cDNA transcribed from chicken beta-actin promoter led to constitutive expression of C42 specific RNA as well as IDO activity. This cDNA clone will be useful in studying the role of IDO in the biological effects of IFN-gamma, and the regulation of IDO gene by IFN-gamma.

Amino Acid Sequence↗
PubMed1990

[The effect of three kinds of thyroid hormone preparations on serum thyroid hormone and TSH in primary hypothyroidism].

Thirty-eight cases of primary hypothyroidism were treated prospectively with three kinds of thyroid hormone preparations, including Levothyroxine, L-triiodothyronine and dry thyroid preparation. A protocol of different dosages with same biologic effects was followed: 100 micrograms Levothyroxine approximately 40-60 mg dry thyroid preparation approximately 30-40 micrograms L-triiodothyronine. During drug replacement treatment, the change serum T3 and TSH is more sensitive than that of serum T4 and reverse T3. Both of serum T3 and T4 can directly inhibit the secretion of pituitary TSH, but serum T4 is more closely related to TSH than is T3. In judging the overdose, the level of serum T4 is a superior indicator to the level of T3. The best time to take thyroid hormone preparations is at bedtime.

Humans↗
PubMed1990

[Expression of MG7 corresponding antigen in gastric polyp and its relation to gastric carcinoma].

Forty-nine cases of gastric polyp (GP) were studied by histologic classification and immunohistochemical localization of monoclonal antibody MG 7 against gastric carcinoma. There were 12 cases (24.5%) of inflammatory polyp; 19 cases (38.8%) of hyperplastic polyp and 18 cases (36.7%) of adenomatous polyp. 3 cases (6.1%) of GP were malignant, among which 2 (11.1%) were adenomatous polyp and 1 (5.3%) was hyperplastic polyp. Seventeen cases (34.7%) of GP were MG 7 positive by ABC method, including 7 (36.8%) of hyperplastic polyp and 10 (55.5%) of adenomatous polyp. The inflammatory polyps were negative, and all of the cases with malignancy were strongly positive. The results showed that both GP and gastric carcinoma express MG 7 related antigen. These suggest that adenomatous polyp and hyperplastic polyp are closely related with gastric carcinogenesis.

Antibodies, Monoclonal↗
PubMed1990

[Microsurgery to treat lesions in or near the eyeball wall].

Four sub-retinal cysticerci and 12 cases of nonmagnetic intraocular foreign bodies near the eyeball wall were first localized with indirect ophthalmoscopy and then removed successfully under surgical microscopy. Three layers, ie white sclera, black supra-choroid pigment and light brown choroidal tissue with white vascular pattern were encountered before reaching the sub-retinal larval. The ischemic appearance of the choroid probably was caused by compression of the larval underneath it. Intraocular foreign bodies usually appeared in the wound accompanied by liquified vitreous as soon as the incision was made. If intraocular inflammation exist, foreign body can be found within the pus or dense exudates.

Adult↗
PubMed1986

Respiratory dysfunction in patients with common variable hypogammaglobulinemia.

Patients with common variable hypogammaglobulinemia (CVH) are susceptible to recurrent respiratory infections. We studied the prevalence and severity of respiratory dysfunction in 32 patients with CVH by measuring routine pulmonary function tests (PFT) and interpreting chest radiographs using a quantitative score system. Pulmonary symptoms were determined by patient interview and standard questionnaire. The mean age of 29 living patients was 28 +/- 2.2 yr; there were 22 males and 10 females. The mean age at diagnosis was 17.3 +/- 2.4 yr. Sinopulmonary symptoms were present in all 32 patients and included chronic sinusitis, otitis, bronchitis, recurrent pneumonia, and bronchiectasis. Complete PFT in 25 patients revealed restrictive, obstructive, and normal patterns in 10, 6, and 9 patients, respectively. Nine patients had dyspnea on exertion. Recent chest radiographs in 32 patients showed evidence of recurrent pulmonary infection, including air trapping, linear markings, and pleural abnormalities. Panlobular emphysema, documented in one case at autopsy, was suggested in 5 other patients by the presence of lower lobe bullous lesions and marked lower lobe hyperlucency on chest radiographs. The forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) had remained stable in 19 adults (18 receiving adequate immunoglobulin replacement therapy) for 6.9 +/- 0.7 yr. The expected increase of the FEV1 and FVC with growth was normal in 6 of 8 children (all 8 receiving adequate therapy). Chest radiograph scores deteriorated only slightly from 20.3 +/- 0.6 to 18.4 +/- 0.8 (25 = normal) during the 6.9 +/- 0.7 yr in 30 patients (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Soluble peptidoglycan fragments stimulate antibacterial protein synthesis by fat body from larvae of Manduca sexta.

Both hemocytes and fat body from larvae of Manduca sexta, which have been injected with inducers of antibacterial protein synthesis, contain immunoreactive lysozyme. However, fat body is a richer source and has been demonstrated to synthesize and release lysozyme and cecropin-like peptides (bactericidins) in vitro. Fat body secretion of lysozyme and bactericidins is stimulated by addition of soluble peptidoglycan fragments to culture medium. The rate of lysozyme secretion by fat body varies as a function of peptidoglycan inducer concentration. These data are consistent with the hypothesis that, in vivo, bacteria must be phagocytized and partially degraded (processed) by hemocytes to generate a signal (peptidoglycan) that subsequently induces antibacterial protein synthesis by fat body.

Animals↗
PubMed1981

Plasma testosterone, high density lipoprotein cholesterol and other lipoprotein fractions.

High density lipoprotein (HDL) cholesterol levels are strongly related to risk of heart attack. Identification of determinants of high density lipoprotein cholesterol may provide important information concerning the cause of heart disease. The relation between one possible determinant, testosterone, and high density lipoprotein cholesterol and other lipoprotein fractions was evaluated in 247 middle-aged men. The results indicate that testosterone levels (both free and total) were positively correlated with high density lipoprotein cholesterol (r = +0.24, p less than 0.01) and negatively correlated with triglycerides and very low density lipoprotein cholesterol. The association between testosterone and high density lipoprotein cholesterol could not be explained by intake of alcohol, obesity, age, smoking or physical activity. Furthermore, the relation of testosterone to HDL cholesterol was independent of the relation of testosterone to very low density lipoprotein (VLDL) cholesterol or triglycerides.

Age Factors↗
PubMed1981

The relationship between alcohol consumption, liver enzymes and high-density lipoprotein cholesterol.

High-density lipoprotein (HDL) cholesterol concentrations are inversely related to risk of heart attack. Alcohol consumption is a primary factor related to increased HDL concentrations. We investigated HDL cholesterol before and after cessation of high alcohol consumption in alcoholics. Men admitted to an alcohol detoxification hospital had a mean HDL cholesterol level of 85 mg/dl, which is almost twice that found in the general population. After 4 days of treatment, HDL cholesterol levels decreased an average of 12.5 mg/dl. The decrease was directly correlated with the initial HDL cholesterol levels and inversely correlated with the change in triglyceride levels. Alcoholics who abstained for at least 1 month had HDL cholesterol concentrations similar to those of the general population. The increased HDL cholesterol levels in the alcoholics were highly correlated with liver enzyme concentrations, especially SGOT. The results suggest that alcohol increases HDL cholesterol concentrations through hepatic microsomal enzyme induction.

Adult↗
PubMedDate not supplied

A new antigen retrieval method using citraconic anhydride for immunoelectron microscopy: localization of surfactant pro-protein C (proSP-C) in the type II alveolar epithelial cells.

In the attempt to develop a pre-embedding immunoelectron microscopic method with improved ultrastructral morphology, we examined an antigen retrieval (AR) method using citraconic anhydride, and compared the effects of glutaraldehyde fixation with routine paraformaldehyde fixation in the pre-embedding immunoelectron microscopic method with reference to the localization of surfactant-associated pro-protein C (proSP-C) in the lung. The glutaraldehyde-fixed tissues were immunostained after AR in 0.05% citraconic anhydride solution, pH 7.4, at 98 degrees C for 60 min. In routine pre-embedding immunoelectron microscopic method using paraformaldehyde fixation, proSP-C positive products were distributed sporadically in the type II alveolar epithelial cells. In glutaraldehyde-fixed tissues without the AR method, proSP-C products were not detected, however after AR in citraconic anhydride proSP-C positive products were distributed specifically, in rough endoplasmic reticulum membranes, Golgi complex membranes, multivesicular bodies and osmiophilic lamellar bodies. The positive proSP-C products also showed lattice-like structures in the alveoli. Thus, the present AR method provides successful pre-embedding immunoelectron microscopy of glutaraldehyde-fixed tissues.

Animals↗