Search PubMed⌕ Search

Biomedical subjects

D Yang

Publications and source records attributed to D Yang.

At least 343 records · Page 19Linked to original sources
PubMed1996

Increased incidence of Clostridium difficile-associated diarrhea following decreased restriction of antibiotic use.

Removal of antimicrobial agents from formulary restriction status at our center was followed by an increase in the incidence of Clostridium difficile-associated diarrhea. The mean monthly incidence of C. difficile diarrhea for the 12-month period before institution of decreased restriction of antibiotic use was 3.4 infections per 1,000 admissions and rose to 6.2 infections per 1,000 admissions during the following 4-month period (P < .05). Patients who developed disease before and after decreased restriction of antibiotics were similar in terms of the mean number of antimicrobial agents administered and mean duration of therapy. The most commonly administered agents whose use preceded the onset of disease were cefazolin, trimethoprim-sulfamethoxazole, ampicillin, ticarcillin/clavulanate, and gentamicin (the latter drug was always used in combination with other agents). Immunoblot typing indicated that there was no association between C. difficile strains and administration of specific agents. There was no coincidental epidemic to account for the increased incidence of infection. The increased incidence of C. difficile disease is a potential problem that may occur following removal of extended-spectrum antimicrobial agents from formulary restriction status.

Adult↗
PubMed1996

Identification of domains in rubella virus genomic RNA and capsid protein necessary for specific interaction.

In rubella virus-infected cells, genomic 40S and subgenomic 24S RNAs are present in the cytoplasm of infected cells. However, encapsidation by rubella virus capsid protein is specific for 40S genomic RNA. As a first step toward understanding the assembly of rubella virus nucleocapsid at the molecular level, the interaction between capsid protein and genomic RNA was studied by Northwestern (RNA-protein) blot analysis. RNA probes prepared by in vitro transcription were used to localize the RNA sequence that participates in binding to the capsid protein. We have identified a 29-nucleotide RNA sequence (nucleotides 347 to 375) that is essential for the binding. By using overlapping synthetic peptides of capsid protein, a peptide domain (residues 28 to 56) that displays specific RNA-binding activity of capsid protein has been located. This result suggests that the specific recognition of viral RNA during rubella virus assembly involves, at least in part, the nucleocapsid protein.

Amino Acid Sequence↗
PubMed1996

Direct interactions of coxsackievirus B3 with immune cells in the splenic compartment of mice susceptible or resistant to myocarditis.

In vitro replication of coxsackievirus B3 (CVB3) in cells of the immune system derived from uninfected adolescent A/J and C57BL/6J mice and replication of CVB3 in and association with immune cells from spleens of infected animals in vivo were assessed. Nonstimulated or mitogen-stimulated spleen cells were minimally permissive for viral replication during an 8-h period. Three days postinfection (p.i.), CVB3 RNA was localized in vivo to B cells and follicular dendritic cells of germinal centers in both A/J and C57BL/6J mice; however, extrafollicular localization was greater in C57BL/6J mice (P = 0.0054). Although the pattern of CVB3 RNA localization was different, the total load of infections virus (PFU per milligram of tissue) was not different. Splenic CVB3 titers (PFU per milligram of tissue) in both strains were maximal at day 3 or 4 p.i. and were back to baseline by day 7 p.i., with most infectious virus being non-cell associated. CVB3 titers (PFU per milligram of tissue) correlated directly with in situ hybridization positivity in splenic follicles and extrafollicular regions in both murine strains; however, follicular hybridization intensity was greater in A/J mice at day 5 p.i. (P = 0.021). Flow cytometric analysis demonstrated that 50.4% of total spleen cells positive for CVB3 antigen were B cells and 69.6% of positive splenic lymphocytes were B cells. Myocardial virus load in C57BL/6J mice was significantly lower than that in A/J mice at days 4 and 5 p.i. These data indicate that CVB3 replicates in murine splenocytes in vitro and in B cells and extrafollicular cells in vivo.

Animals↗
PubMed1996

Insulin-like growth factor II blocks apoptosis of N-myc2-expressing woodchuck liver epithelial cells.

N-myc2 and insulin-like growth factor II (IGF-II) are coordinately overexpressed in the great majority of altered hepatic foci, which are the earliest precancerous lesions observed in the liver of woodchuck hepatitis virus carrier woodchucks, and these genes continue to be overexpressed in hepatocellular carcinomas (HCCs). We have investigated the function of these genes in woodchuck hepatocarcinogenesis by using a woodchuck liver epithelial cell line (WC-3). WC-3 cells react positively with a monoclonal antibody (12.8.5) against woodchuck oval cells, suggesting a lineage relationship with oval cells. Overexpression of N-myc2 in three WC-3 cell lines caused their morphological transformation and increased their growth rate and saturation density in medium containing 10% serum. Removal of serum from the medium increased cell death of the N-myc2-expressing lines, whereas cell death in control lines was minimal. The death of N-myc2-expressing WC-3 cells was accompanied by nucleosomal fragmentation of cellular DNA, and DAPI (4',6-diamidino-2-phenylindole) staining revealed condensation and fragmentation of the nuclei, suggesting that N-myc2-expressing WC-3 cells undergo apoptosis in the absence of serum. In colony regression assays, conducted in the absence of serum, control colonies were stable, while N-myc2-expressing colonies regressed to various degrees. Addition of recombinant human IGF-II to the serum-free medium blocked both cell death and colony regression in all the N-myc2-expressing lines. Therefore, coordinate overexpression of N-myc2 and IGF-II in woodchuck altered hepatic foci may allow cells which otherwise might die to survive and progress to hepatocellular carcinoma.

Animals↗
PubMed1996

Noninvasive probing of citric acid cycle intermediates in primate liver with phenylacetylglutamine.

In human and primate liver, phenylacetate and glutamine form phenylacetylglutamine, which is excreted in urine. Probing noninvasively the labeling pattern of liver citric acid cycle intermediates with phenylacetylglutamine assumes that the labeling pattern of its glutamine moiety reflects that of liver alpha-ketoglutarate. To validate this probe, we infused monkeys with [U-13C3]lactate, [3-13C]lactate, [1, 2-13C2]acetate, [2-13C]acetate, [U-13C3]glycerol, or 2-[3-13C]ketoisocaproate and compared the labeling patterns of urinary phenylacetyl-glutamine with those of glutamate and glutamine in liver, plasma, muscle, and kidney and liver alpha-ketoglutarate. Only with [U-13C3]lactate or [3-13C]lactate does the labeling pattern of phenylacetylglutamine reflect patterns of liver alpha-ketoglutarate and glutamate. With [13C]acetate, muscle and kidney glutamate are more labeled than liver metabolites. This confirms that with [13C]acetate, the labeling pattern of liver metabolites is influenced by 13CO2 and [13C]glutamine made in peripheral tissues. Our data validate the use of phenylacetylglutamine labeled from [3-13C]lactate or [3-13C]pyruvate to probe noninvasively the pyruvate carboxylase-to-pyruvate dehydrogenase flux ratio in human subjects.

Animals↗
PubMed1996

Modification of viral myocarditis in mice by interleukin-6.

Inflammatory cytokines play a key role in the myocardial injury produced by viral myocarditis. Although interleukin-6 (IL-6) reportedly possesses antiviral properties, its effect in viral myocarditis is unclear. To investigate the role of IL-6 in viral myocarditis induced by encephalomyocarditis virus (EMCV) in mice, we evaluated (1) the survival rate following IL-6 administration, (2) the viral titer in the heart, (3) viral replication in the heart by in situ hybridization, (4) histopathological changes using immunohistochemical staining, (5) neutralizing antibody against EMCV, (6) circulating interferon and tumor necrosis factor-alpha (TNF-alpha), (7) viral suppression in vitro by IL-6, and (8) natural killer (NK)-cell activity. Eight-week-old C3H/HeJ mice were injected intraperitoneally with EMCV (day 0) and were also injected subcutaneously twice daily for 4 consecutive days with 10 micrograms/0.1 mL of human IL-6 on day -4 (group A), day 0 (group B), or day +4 (group D) for 4 days. As a control, 0.1 mL PBS instead of IL-6 was injected on day 0 for 4 days (group C). Certain mice were killed on day 4. The myocardial virus titers, viral replication in situ, and NK-cell activity in the spleen were determined. Decreased viral titer and viral replication in the heart reduced the titer of circulating TNF-alpha, and lower NK-cell activity was observed in group B versus group C (control group). The titer of neutralizing antibodies against EMCV was significantly (P < .05) increased in group B compared with group C. The remaining mice were killed on days 10 and 30 after infection. The ratio of heart weight (HW) to body weight (BW) and myocardial injury in group B were reduced versus group C on days 10 and 30. The HW of group B on day 30 did not differ from the normal control group. The ratio of splenic weight to BW and the ratio of thymic weight to BW of group B increased on day 10, with expanded follicles observed in the spleen and enlargement of the medulla observed in the thymus. Immunohistochemical study revealed an increased percentage of macrophages in the heart and spleen of group B. In summary, IL-6 reduces myocardial damage in mice with viral myocarditis. Modification of immune responses together with reduction in viral replication appears to be the mechanism of the IL-6 effect. Although IL-6 is likely important in the process of viral antigen presentation, early activation of immune responses and attenuation of viral replication appear most significant, as reflected in the limited time window during which IL-6 is effective in myocarditis.

Animals↗
PubMed1996

[Solitary plasmacytomas of bone and extramedullary plasmacytomas].

Among plasma cell disorders, solitary plasmacytoma (solitary plasmacytoma of bone, SPB and extramedullary plasmacytoma, EMP) is rare as compared with multiple myeloma (MM). Furthermore, the relationship between solitary plasmacytoma and MM remains unclear. Between 1960 and 1994, 24 patients with SPB and 20 with EMP were treated. The criteria for diagnosis were: (1) no evidence of other lesions based on clinical and radiologic examinations; (2) biopsy evidence of a plasma cell neoplasm; (3) bone marrow biopsy specimen with negative findings (less than 10% plasma cells); (4) no anemia, hypercalcemia or renal involvement. The average follow-up period was 112 months (from 6 to 360 months). Fifty-four percent of patients with SBP and 40% of patients with EMP developed MM, however, there was no significant statistical difference between SPB and EMP (P > 0.05). We suggested that solitary plasmacytomas be classified as two types, latent and aggressive. The former was histologically well-differentiated plasmacytoma. The latter was poorly differentiated tumors which easily progress to MM. The treatment of choice is wide excision or thorough curettage, by cryogenic necrosis with liquid nitrogen or cautery of the bony wall with phenol and the cavity filled with bone grafts or cementation. All patients with apparently isolated plasmacytoma should receive local radiotherapy after operation. Adjuvant chemotherapy should be given if the tumour turns out to be poorly differentiated, in order to delay their progression to MM.

Adult↗
PubMed1996

In vitro evaluation of polymeric matrix and porous biodegradable reservoir devices for slow-release drug delivery.

BACKGROUND AND OBJECTIVE: Biodegradable polymeric devices were evaluated in vitro for intravitreal drug delivery. MATERIALS AND METHODS: The matrix (short-term drug delivery) and the porous (longer-term drug delivery) reservoir devices were made from polycaprolactone of two molecular weights (30,000 and 56,000). Matrix devices were loaded with 5-fluorouracil or ganciclovir. Porous reservoirs were loaded with 5-fluorouracil, ganciclovir, 5-carboxyfluorescein, or foscarnet. The release was monitored in phosphate-buffered solution using ultraviolet spectrophotometry. RESULTS: Release from the matrix devices was characterized by an initial burst, followed by a nonlinear release. The porous reservoirs demonstrated zero order linear release of drugs, sustained up to 250 days in this experiment. CONCLUSIONS: The matrix device is capable of sustained release over several months; the porous reservoir can deliver drugs for over 1 year. Further studies are needed to evaluate in vivo biodegradation behavior and toxicity of drugs used for sustained release.

Antiviral Agents↗
PubMed1996

[Normal distribution of CBF with advancing age measured by HMPAO SPECT].

SPECT with Tc-99m HMPAO was used to determine global and regional cerebral blood flow (CBF) in 52 healthy subjects ranging from 2 to 85 years old. These subjects were divided into six groups according to age. SPECT images were obtained using a three-headed gamma camera system equipped with low-energy ultra-high-resolution fan beam collimators (LEUHR-FAN). Absolute CBF values were estimated in 21 of 52 subjects using a Patlak plot technique. The SPECT images were obtained 5-10 minutes after the injection of 740MBq of Tc-99m HMPAO. A supercomputer system was used to reconstruct transverse section images at levels of 8, 32, 44 and 67 mm above the orbitomeatal line (2.7 mm thickness), and oblique transverse section images parallel to the temporal lobe (1.56 mm thickness). Lassen's linearization correction was applied. The average counts of four or five ROIs in eight regions were calculated. The cerebral to cerebellar activity ratio (C/C ratio) was estimated by dividing counts in the cerebral regions by those in the cerebellum. The interhemispheric differences in C/C ratios in the eight regions of all the groups were not significant. In elderly subjects there was a tendency for C/C ratios to decrease except in the thalamus and basal ganglia. Mean global CBF in 21 of 52 subjects was 49.3 +/- 10 ml/100g/min. A significant negative correlation was found between global CBF and advancing age (p < 0.05), particularly in males (p < 0.01).

Adolescent↗
PubMed1996

Molcecular cloning of human antizyme cDNA.

We have cloned the cDNA encoding the human ornithine decarboxylase antizyme from a 5'-stretch cDNA library of human B-cell lymphoma Daudi. The cloned human antizyme cDNA fragment consists of 1063 bp, has 80% homology to the rat antizyme cDNA, but shows almost no homology to the E. coli antizyme gene. Northern hybridization analysis shows that this gene is expressed in a number of human cell lines with an estimated mRNA transcript size of about 1.1 kb. The size of the mRNA suggests that the cloned cDNA fragment probably represents the full length of human antizyme mRNA transcript. Comparison of the human and rat antizymes demonstrates that they are highly conserved at both nucleotide and peptide levels.

Amino Acid Sequence↗
PubMed1996

Immunohistochemical detection and significance of hepatitis C virus antigen.

OBJECTIVE: To study the expression and clinical significance of hepatitis C virus (HCV) antigens in liver tissues of patients with liver disease. PATIENTS AND METHODS: Hepatitis C virus antigen in paraffin-embedded liver tissues was detected by immunohistochemical method using polyclonal anti-HCV and monoclonal anti-HCV NS3. RESULTS: Among the 252 liver tissues, 25 (9.92%) were positive for HCAg (detected with polyclonal anti-HCV), and 19 (7.74%) were positive for HCV-NS3 (detected with monoclonal anti-HCV-NS3). All of the 19 HCV NS3 positive tissues were also positive for HCAg. Their distribution in liver tissue was similar, locating in the cytoplasm of liver cells. In most tissues, the positive cells scattered in liver lobulus, without obvious approach to the necrosis and infiltration aggregation; while a few samples showed positive cells clustered or diffused, with some necrosis or/and inflammatory infiltration. Of the 252 sera samples, 71 had HCV antibody or/and HCV RNA, showing a good correlation between HCV antigen in liver tissues and HCV marker in sera, but the detection rate of HCV antigen in liver tissues was much lower than that of HCV markers in sera. Two cases had HCV antigen in their liver with no HCV markers in their sera. CONCLUSION: Stored paraffin-embedded liver tissue can be used in the study of the immunopathology of HCV: no definite relationship between the expression of HCV antigens and liver damage has been found. Further study of the pathogenesis of HCV is needed.

Hepacivirus↗
PubMed1996

[Expression of thyrotropin receptor gene in autoimmune thyroid disease and the relation to expression of HLA genes].

OBJECTIVE: To investigate the expression of TSH receptor in autoimmune thyroid disease (AITD) and the relation to expression of HLA I and II genes. METHODS: The TSH receptor transcript levels were examined in 10 human thyroid fragments by Northern blot analysis. Graves' disease 7, Hashimoto's disease 2, and 1 healthy thyroid gland. RESULTS: TSH receptor transcript levels were higher in Graves' disease than in Hashimoto's disease and healthy control. CONCLUSION: TSH receptor expression was inversely related to HLA I and II expression and lymphocyte infiltration.

Gene Expression↗
PubMed1996

[Operative treatment of the endobronchial tuberculosis with cicatricial bronchiarctia].

OBJECTIVE: The experience of surgical treatment in 32 patients with cicatricial brochiarctia by endobronchial tuberculosis was reported. METHOD: The modes of surgical treatment in the series include: sleeve resection was done in 19 cases, lobectomy in 4 cases, pneumonectomy in 7, and left principal bronchial reconstruction in 2 cases. RESULTS: The results were excellent and without operative death. Serious postoperative complication was bronchopleural fistula in one case. The patient was treated by surgical repair of the bronchial stump and buttressed with vascularized pedicle flaps of omentum in the second operation. 2 cases of 32 patients were affected with mild stenosis of bronchial anestomosis after a follow-up of 12 to 18 months. CONCLUSIONS: It was suggested that when the patient developed the endobronchial tuberculosis with cicatricial bronchiarctia, corrective operation should be performed as early as possible, and the sleeve resection should be the first choice.

Adolescent↗
PubMed1996

[Immunohistochemical study of endothelin-1 in adrenal tumors].

10 cases of aldosteronoma, 10 cases of pheochromocytoma and 10 cases of adrenocortical adenoma and hyperplasia were studied by using immunohistochemical staining for ET-1. All of the tumors were stained positivily for ET-1, ranging from weak diffuse (+) staining to moderate staining (++). In aldosteronomas ET-1 receptro may be down-regulated and ET-1 may play a paracrine role in regulating catecholamine in pheochromocytoma.

Adolescent↗
PubMed1996

[Surgical treatment of pulmonary metastasis from renal cancer: analysis of 9 cases].

Nine patients with pulmonary metastasis from renal cancer were subjected to surgical treatment which included wedge resection (2 cases) and lobectomy (9). One case of multiple lesions in bilateral lungs was treated in the same time by cryosurgery and fulguration. The survival time after operation ranged from 5 to 90 months. In this series, four cases are still alive, others survived for 13 months, 20 months, 34 months, and 90 months, respectively. We suggest that the more active attitude should be taken for the surgical treatment of pulmonary metastasis.

Adenocarcinoma, Clear Cell↗
PubMed1996

[An experimental study on immune mechanism after alkali burn in the anterior segment of rabbit eye].

OBJECTIVE: To study the immunologic mechanism of corneal ulceration after alkali burn. METHODS: 55 rabbits with alkali burn in right eye were randomly divided into two groups. In group I (31 animals), the level of circulating immune complex (CIC), the rate of red blood cell C3b receptor complex rosette (RBC-C3bRR) and immune complex rosette (RBC-ICR) were measured respectively at 7, 14, 21, 35, 49 days after alkali burn. In Group 2 (24 animals), the immune complex was detected by means of immunofluorescence (IF) and immunogold-silver staining (IGSS) in burned tissues at 21 days after burn. Histopathologic changes were also observed under light microscope. RESULTS: CIC, the rate of RBC-C3bRR and RBC-ICR were markedly increased 14 to 21 days after burn. In the mean time, the deposition of immune complex was found in burned tissues and the accumulation of polymorphonuclear leukocyte (PMN) was observed at the base of corneal ulcer. CONCLUSIONS: The immune mechanism indeed participates in the pathogenesis of corneal ulceration and also aggravates the progress of ulceration on the base of chemical injury.

Animals↗
PubMed1995

Structure and isomerization of an intrastrand cisplatin-cross-linked octamer DNA duplex by NMR analysis.

The anticancer platinum compound cis-Pt(NH3)2Cl2 (cisplatin) forms covalent cross-linked adducts with DNA, with the intrastrand didentate adduct between two adjacent guanines being the major product. The platinum atom is coordinated at the N7 positions of adjacent guanines. The duplex consisting of d(CCTG*G*TCC) and its complement d(GGACCAGG), where G*G* stands for the cisplatin cross-linked lesion site, has been analyzed by 1D- and 2D-NMR spectroscopy and its structure solved by the NOE-restrained refinement procedure with the aim to understand the structural distortion associated with the lesion. The refined duplex is unwound (approximately -21 degrees) and kinked (approximately 58 degrees) toward the major groove at the G*G* site, and the minor groove is significantly widened. The deoxyriboses of the G4* and G5* nucleotides are of the N-type (C3'-endo) and S-type (C2'-endo) conformations, respectively. The two guanine bases adopt the R-configuration (the alpha/beta angles being 112 degrees/290 degrees, respectively), such that the G5*H8 proton (upfield at 8.19 ppm) senses the ring current shielding effect of the G4* base (G4*H8 at 8.76 ppm). The G4*.C13 base pair is perturbed significantly, consistent with the lack of detection of its imino proton. The intrastrand Pt-G*pG* cross-link is metastable in the present DNA duplex. The molecule is slowly converted into a more stable interstrand didentate adduct (between G4 and G9) promoted by the presence of the nucleophilic chloride ion.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗