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Biomedical subjects

J Wan

Publications and source records attributed to J Wan.

13 recordsLinked to original sources
PubMed1992

Brefeldin A enhances receptor-mediated transcytosis of transferrin in filter-grown Madin-Darby canine kidney cells.

The effects of brefeldin A (BFA) on transferrin (Tf) transcellular transport, Tf receptor (TfR) distribution, and TfR-mediated endocytosis in filter-grown Madin-Darby canine kidney (MDCK) cells were studied. BFA (1.6 micrograms/ml) markedly enhanced the transcytosis of 125I-labeled Tf (125I-Tf) in both apical-to-basal and basal-to-apical directions; yet, BFA did not enhance the transcytosis of either native horseradish peroxidase (HRP) or membrane-bound HRP-poly(L-lysine) conjugates. Furthermore, this enhanced transcytosis of 125I-Tf was abolished either by competition with excess unlabeled Tf or by incubation at temperatures less than or equal to 25 degrees C. In addition, BFA treatment to MDCK cells: (a) increased 125I-Tf specific binding to the apical membrane and decreased 125I-Tf specific binding to the basal membrane; (b) decreased TfR recycling at the basolateral membrane; (c) altered the apical/basolateral distribution of TfRs in favor of the apical side; and (d) markedly increased 59Fe extraction, but not transcytosis, from apically endocytosed 59Fe-loaded Tf. These effects are consistent with a model in which BFA alters the traffic pattern of internalized Tf by decreasing basolateral TfR recycling, while diverting the nonrecycled fraction to the apical side of the cell. Our results indicate that, unlike the reported inhibition of polymeric IgA transcytosis (Hunziker, W., Whitney, J. A., and Mellman, I. (1991) Cell 67, 617-627), BFA can enhance the transcytosis of Tf in MDCK cells. Thus, by altering the intracellular traffic of ligand-receptor complexes, BFA can elicit either a decrease or an increase in transcytosis depending on the nature of the intracellular receptor processing.

Animals↗
PubMed1992

CDC14 of Saccharomyces cerevisiae. Cloning, sequence analysis, and transcription during the cell cycle.

We have cloned, mapped and sequenced the complete CDC14 gene of Saccharomyces cerevisiae and characterized its transcription during the cell cycle. CDC14 was found within a 3.5-kilobase pair XhoI-XbaI fragment of chromosome VI. The DNA sequence reveals an open reading frame capable of encoding a 423-amino acid polypeptide. Protein sequence comparisons through the Prosite, GenBank and EMBL databases allowed us to identify a conserved protein tyrosine phosphatase active site in the encoded CDC14 protein beginning at amino acid 153. Disruption demonstrates that CDC14 is an essential gene. The level of the CDC14 transcript appears to be weakly cell cycle-regulated and has a periodicity which lags approximately 15 min behind histone HTB1 mRNA accumulation levels. DNA sequence analysis has identified a region within the CDC14 promoter which bears a striking resemblance (15 out of 21 base pairs identity) to the cell cycle regulation region of the promoter of the histone H2A1-H2B1 (HTA1-HTB1) gene pair. The cell cycle regulation sequence is responsible for the periodic accumulation and hydroxyurea sensitivity of the histone HTA1-HTB1 message. However, unlike histone mRNA, which is repressed upon hydroxyurea arrest, CDC14 mRNA appears to be unaffected. This suggests that CDC14 and histone genes are regulated by different mechanisms during the cell cycle. Furthermore, superhelical density measurements suggest that CDC14 is not involved in nucleosome assembly.

Amino Acid Sequence↗
PubMed1992

The treatment of urinary incontinence in children using glutaraldehyde cross-linked collagen.

Periurethral injection of polytetrafluoroethylene (PolyTef) paste has been used to correct urinary incontinence for 2 decades. The controversy over distant migration of the paste has led to an interest in alternative materials particularly for the pediatric patient. Glutaraldehyde cross-linked collagen, derived from bovine dermal collagen, is effective in treating urinary incontinence in adults. Eight children with structural urinary incontinence underwent glutaraldehyde cross-linked collagen injection. Fluorourodynamic studies preceded and followed the injections. An average of 10.9 cc glutaraldehyde cross-linked collagen was injected per treatment (range 2.5 to 20). The number of injections per child ranged from 1 to 6 (mean 2.1) and followup averaged 13.75 months (range 6 to 33). Overall, 88% of the patients were cured or improved: 5 (63%) became continent, 2 were improved and 1 had no effect.

Adolescent↗
PubMed1992

Urinary tract status of patients with neurogenic dysfunction presenting with upper tract stone disease.

We treated 71 patients with neurogenic vesical dysfunction between September 1983 and June 1990 for upper tract stones. We studied these patients to determine the time course of stone development and the presence of associated urological abnormalities. There were 44 male and 27 female patients 6 to 72 years old. Lower urinary tract dysfunction resulted from spinal cord injuries in 34 patients (48%), myelodysplasia in 19 (27%), multiple sclerosis in 12 (17%) and other diagnoses in 6 (8%). Of 71 patients 21 (30%) were managed by an ileal loop, 12 (17%) by a Foley catheter, 10 (14%) by a suprapubic tube, 10 (14%) by ureterostomy, 5 (7%) by vesicostomy, 8 (11%) by intermittent catheterization, and 5 (7%) by diaper, Créde's voiding or condom catheterization. Stone disease developed within 1 to 22 years. Patients with an indwelling catheter or supravesical diversion fared worse than those managed by intermittent catheterization or vesicostomy; they had higher rates of renal unit loss, renal parenchymal damage, decreased renal function, hydroureter, and staghorn and bilateral calculi. All of the listed methods of management were contemporaneous, suggesting the continued use of methods proved to be associated with upper tract deterioration.

Adolescent↗
PubMed1992

Retroperitoneal neurogenous choristoma.

A 6-year-old girl with urinary complaints underwent ultrasonography, which revealed a retroperitoneal cystic mass adjacent to the left kidney. Computerized tomography did not demonstrate whether the mass was an adrenal cyst or a duplicated upper pole segment. Exploration revealed a neurogenous choristoma, which is a collection of histologically normal tissue that is ectopically situated. We believe that this is the first report of this rare entity occurring in the retroperitoneum.

Child↗
PubMed1992

Study of radiation dosage in esophageal carcinoma.

A series of 221 esophageal carcinoma patients admitted from 1983 to 1984 for radiotherapy was randomised into two groups. Group A was given 50 Gy/5 wk, 111 patients and Group B 70 Gy/7 wk, 110 patients. Three in group A and 11 in Group B did not complete their treatment due to adverse reactions. The 5-year survival rates of Groups A and B were 16.7% and 17.2% (P greater than 0.5). Because of the absence of excellent results and higher incidence of discontinuation of therapy in the 70 Gy group, the authors believe that the high dose regimen is not warranted in esophageal cancer.

Aged↗
PubMed1991

Flow cytometric measurement of cell cycle kinetics in rat Walker-256 carcinoma following in vivo and in vitro pulse labelling with bromodeoxyuridine.

Flow cytometric measurements of total DNA content, cell cycle distribution, and bromodeoxyuridine (BrdUrd) uptake were made in rat Walker-256 carcinoma cells. After both in vivo and in vitro pulse labelling with BrdUrd, Walker-256 tumor cells were stained with propidium iodide (PI) to estimate the total DNA content and a monoclonal antibody against BrdUrd to estimate the relative amount of cells in S phase. BrdUrd-labelled single cell suspensions were harvested at different time intervals to determine the movement of these cells within the cell cycle. To increase BrdUrd uptake, fluorodeoxyuridine (FDU), a thymidine antagonist, was also applied in vivo and in vitro. The results indicated exponential growth characteristics for this tumor between days 5 and 8 after implantation. Tumor doubling times, derived from changes in tumor volume in vivo and from the increase in cell number in vitro were similar. The mean time for DNA synthesis was estimated from the relative movement of BrdUrd-labelled cells towards G2. The percent of cells labelled with BrdUrd and the DNA synthesis time were similar regardless of the mode of BrdUrd administration. This study demonstrates that BrdUrd labelling of rat Walker-256 carcinoma cells in vitro yields kinetic estimates of tumor proliferation during exponential growth similar to those with the administration of BrdUrd in the intact tumor-bearing rat.

Animals↗
PubMed1991

Racial differences in social support and mental health in men with HIV infection: a pilot study.

The mediating role of social support in the mental health and behaviours of persons coping with life-threatening chronic illness is of potentially great importance in determining the quality of life of persons with HIV infection (PWHs). As part of a biracial pilot study of the ways black and white men manage the stresses of sexually acquired HIV infection, we have examined the relationship between social support and mental health and behaviours. Forty homosexual/bisexual men (20 white and 20 black) attending a Detroit hospital-based HIV outpatient clinic were recruited for the study and underwent physical and mental health (HSCL-59 and NIMH DIS interview), behavioural and psychosocial evaluations, and a neuropsychologic screening test battery. The black and white men did not differ in terms of age, education, sexual behaviours, physical or mental health status. However, the black men were less likely to be open about their sexuality to their primary social support network, and to report that their social support was less affirmative than did the white men. When correlations between the six-dimensional social support measures (Wortman & O'Brien, 1987) and HSC-L distress scores were examined, both availability of material social support and affirmation were correlated negatively with distress among the white men but positively among the black men. Similarly, the previously observed positive relationship between perceived adequacy of social support and adoption of safer sexual practices was observed among white but not black participants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Psychological↗
PubMed1991

Accelerated hyperfractionation radiotherapy in esophageal cancer. An analysis of 172 cases.

Between February 1989 and May 1983, 172 patients with esophageal carcinoma were given radiotherapy. They were randomly assigned to an accelerated hyperfractionation group and routine fractionation group. There was no statistically significant length of survival difference between these two groups at 1, 3 and 5 years. Therefore accelerated hyperfractionation is useful for its economy of duration and cost.

Adult↗
PubMed1990

A comparison between umbilical artery velocimetry and standard antepartum surveillance in hospitalized high-risk patients.

One hundred forty-six women admitted to the high-risk obstetric unit between November 1987 and December 1988 participated in a study designed to compare Doppler umbilical artery flow studies with standard antepartum testing in the prediction of adverse fetal outcome. A Doppler ultrasound examination was considered abnormal when the average systolic/diastolic ratio was greater than or equal to 4. The antepartum testing consisted of a combined use of nonstress testing and contraction stress testing. If both the Doppler systolic/diastolic ratio and the antepartum testing were abnormal, there was a significantly increased incidence of intrauterine growth retardation (47%), fetal distress necessitating cesarean section (67%), and admission to neonatal intensive care (86%). Doppler umbilical artery flow studies are an important adjunct to antepartum fetal surveillance in high-risk patients but should not determine clinical management when standard antepartum surveillance remains normal.

Blood Flow Velocity↗
PubMed1989

Bladder carcinoma in patients age 40 years or younger.

The records of 26 men and nine women aged 40 years or younger, with transitional cell carcinoma of the bladder, were reviewed. Twenty-eight of the patients presented with gross painless hematuria, and 30 were regular smokers. Twenty-two patients presented with noninvasive disease, five with superficial invasion and eight with deep invasion. The risk of the disease progressing to invasion increased with the grade of the tumor, rising from 24% with Grade 1 to 75% with Grade 3. The patients younger than 30 years presented with a lower grade and a lower stage disease than those older than age 30. Transitional cell carcinoma of the bladder in young adults has a natural history similar to that seen in older patients.

Adolescent↗
PubMed1989

A method for comparing semi-parametric models with parametric models in competing risks analysis.

In survival analysis, Cox's regression model is often used to assess the effect of covariates on the time of failure. This semi-parametric model has been extended to the situation where more than one cause of failure is of interest. In this paper, two semi-parametric models for the analysis of competing risks with covariates in the presence of independent random censoring are considered. Particular attention is devoted to the comparison between the two models. A method using a measure derived from the generalized variance is proposed. This method is illustrated with an example in a cancer clinical trial. A FORTRAN program for the computer implementation of the method is also discussed.

Carcinoma, Squamous Cell↗