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Biomedical subjects

J Young

Publications and source records attributed to J Young.

At least 307 records · Page 17Linked to original sources
PubMed1995

[Preliminary evaluation of composite materials for the repair of incisional hernias].

Recent investigations have shown that direct exposure of the intestines to currently available absorbable and nonabsorbable biomaterials can result in their adhesion to the bowel. This can then lead to bowel obstruction or migration of the mesh into the intestinal lumen and formation of intestinal fistula. It has been suggested by some authors that an absorbable covering of the peritoneal side of a nonabsorbable mesh would prevent adhesions and biomaterial related intestinal fistula formation. However, the effectiveness of such a combination has not been substantiated by recent experimental and clinical studies. This preliminary report examines the feasibility of combining porous and non-porous biomaterials for the creation of a composite that would incorporate with the abdominal wall without adhering to the intestines.

Animals↗
PubMed1995

History lessons.

Interest in nursing history has grown in North America over the past two decades, in part because of the increase in feminist and nurse historians, but also because of the realization that nursing history can contribute much to the study of health and social issues.

Historiography↗
PubMed1994

Hyperfractionated total lymphoid irradiation and cyclophosphamide for preparation of previously transfused patients undergoing HLA-identical marrow transplantation for severe aplastic anemia.

PURPOSE: To assess the immunosuppressive capacity of hyperfractionated total lymphoid irradiation and cyclophosphamide for transplantation of unmodified allogeneic marrow in sensitized aplastic anemia patients. METHODS AND MATERIALS: From February 1983 to September 1990, 23 multiply transfused aplastic anemia patients underwent unmodified bone marrow transplantation from HLA genotypically identical sibling donors following preparation with 6 Gy hyperfractionated total lymphoid irradiation and 160 mg/kg cyclophosphamide. Graft-versus-host disease prophylaxis included steroids in one patient, methotrexate in four, cyclosporine in seven, and methotrexate/cyclosporine in 12. There were 17 males and 6 females with a median age of 13 (range: 2.5-32). RESULTS: One patient died early before engraftment of bacterial sepsis. Twenty-two patients were evaluable for engraftment. Three experienced graft failure including one primary, and two late graft failures associated with cyclosporine withdrawal. Acute graft-versus-host disease occurred in 7/22 (> or = grade II in 6), and chronic graft-versus-host disease in 3/17 patients. Except for a patient who received total body irradiation for a second transplant, no patient in this series developed interstitial pneumonia. Fifteen patients are alive with follow-up of 38-125 months (median 68). The overall actuarial survival at 5 years is 69%, at 8 years it is 60%, with one late death. The survival of adult patients was similar to that of younger patients (> or = 16 years old: 63%, < 16 years old: 55%). The development of acute graft-versus-host disease adversely influenced survival (88% with Grade 0-I, 17% with grade II-IV; p = 0.002). No hypothyroidism or secondary malignancies have been documented in this series. CONCLUSION: Pretransplant immunosuppression with 6 Gy of hyperfractionated total lymphoid irradiation and 160 mg/kg CY reduces but does not eliminate the incidence of graft failure in sensitized aplastic anemia patients. The dose and the mode of administration of total lymphoid irradiation in this trial may be associated with a lower incidence of late side effects. Survival is comparable to that obtained using preparative regimens without radiation.

Adolescent↗
PubMed1994

Experimental evaluation of a new composite mesh with the selective property of incorporation to the abdominal wall without adhering to the intestines.

This preliminary study examined the possibility of preventing intestinal adhesions to biomaterials while preserving their incorporation with the abdominal wall. White New Zealand rabbits received intraperitoneal implants of different biomaterials for repair of defects created on the abdominal wall. The following biomaterials were used: polypropylene, polyester, expanded polytetraflueroethylene, polypropylene mesh/polypropylene sheeting (polypropylene mesh covered with polypropylene sheeting on the peritoneal side), polypropylene/silastic, polypropylene/polyglactin, polypropylene/polyglycolic acid, and polypropylene/fibrin. All biomaterials evaluated caused adhesions to the intestines except for polypropylene mesh/polypropylene sheeting and polypropylene mesh/silastic composites. Because adhesion of the intestine to the biomaterial is the first stage of biomaterial-related intestinal fistula, its prevention is logical for the elimination of this complication. Composites with the selective property of adhering to the abdominal wall, yet sparing the viscera, would facilitate thoracic and abdominal wall surgeries, as well as intraperitoneal laparoscopic hernioplasties.

Abdominal Muscles↗
PubMed1994

Recombinant protein expression in a Drosophila cell line: comparison with the baculovirus system.

In this report, we compare two different expression systems: baculovirus/Sf9 and stable recombinant Drosophila Schneider 2 (S2) cell lines. The construction of a recombinant S2 cell line is simple and quick, and in batch fermentations the cells have a doubling time of 20 hours until reaching a plateau density of 20 million cells/ml. Protein expression is driven by the Drosophila Metallothionein promoter which is tightly regulated. When expressed in S2 cells, the extracellular domain of human VCAM, an adhesion molecule, is indistinguishable from the same protein produced by baculovirus-infected Sf9 cells. Additionally, we present data on the expression of a seven trans-membrane protein, the dopamine D4 receptor, which has been successfully expressed in both systems. The receptor integrates correctly in the S2 membrane, binds [3H]spiperone with high affinity and exhibits pharmacological characteristics identical to that of the receptor expressed in Sf9 and mammalian cells. The general implications for large scale production of recombinant proteins are discussed.

Animals↗
PubMed1994

Loss of heterozygosity on the long arm of chromosome 11 in colorectal tumours.

We have examined a series of human colorectal adenomas, carcinomas and cell lines derived from human colorectal cancer for loss of heterozygosity (LOH) on chromosome 11q22-23 by polymerase chain reaction (PCR) amplification of a microsatellite polymorphism of the dopamine D2 receptor (DRD2) locus. LOH was demonstrated in 5/30 (16.7%) adenomas and 23/68 (33.8%) carcinomas. Only 2/20 (10%) cell lines showed homozygosity which could potentially be as a consequence of LOH. This moderate level of loss in the tumour samples was probably not an underestimation as a result of excessive stromal contamination because high rates (68-77%) have been detected in the same samples on chromosomes 17 and 18. In contrast to a previous report, LOH in carcinomas at 11q22-23 occurred at a lower frequency and was not associated with Dukes' stage, degree of differentiation, mucin production or the location of the cancer. However, a significant association was found between LOH on chromosome 11 and chromosome 14. Thus, inactivation of any putative tumour-suppressor gene at 11q22-23 by LOH is not a very common event in the development of colorectal tumours, but may be biologically significant if accompanied by chromosome 14 deletions.

Adenoma↗
PubMed1994

Primary adrenal and thyroid insufficiencies associated with hypopituitarism: a diagnostic challenge.

Polyglandular syndromes have been described for many years but only one case of panhypopituitarism with adrenal and thyroid insufficiencies has been documented. We present a 69-year-old woman with the initial diagnosis of idiopathic primary hypopituitarism. An associated primary adrenal disease was suspected on low plasma aldosterone and increased plasma renin values during unjustified withdrawal of treatment. The complete absence of cortisol response to long-term ACTH administration confirmed the diagnosis. In addition, primary hypothyroidism was demonstrated by the absence of radioiodine uptake by the thyroid gland and the inability to increase T4 secretion after repeated TSH injections. The pattern of hypopituitarism and the coexistence of both adrenal and thyroid deficiencies provide strong evidence for the diagnosis of autoimmune polyglandular syndrome with hypophysitis.

Adrenal Cortex Function Tests↗
PubMed1994

Plasma 3 beta-hydroxy-delta 5-steroids in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

There is little information about the plasma concentrations of 3 beta-hydroxy-delta 5-steroids (delta 5-steroids) in untreated patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. To further study the delta 5 pathway, we measured plasma levels of delta 5- and delta 4-steroids in 21 adult patients with different degrees of 21-hydroxylase deficiency (11 salt-wasters, 5 simple virilizers, and 5 patients with the nonclassical form of the disease). In all patients, investigations were performed after withdrawal of steroid treatment for at least 10 days. In addition, catheterization of gonadal and adrenal veins was performed in two salt-wasting male patients displaying bilateral testicular tumors to study adrenal secretion of delta 5- and delta 4-steroids. In one of them, surgical resection of the intratesticular adrenal rests gave the opportunity to measure 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) activity. In all untreated patients, an increase in plasma delta 4-steroids was observed. In contrast, although plasma levels of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) were not significantly modified in simple virilizers, a paradoxical decrease in all delta 5-steroids was observed in salt-wasters. Catheterization of the adrenal veins confirmed the decrease in delta 5-steroids, particularly DHEA and DHEAS. The androstenedione/DHEA ratio was increased in all patients proportionally to the severity of the disease, suggesting an increase in adrenal 3 beta HSD. In vitro analysis of 3 beta HSD activity showed a 4-fold increase in intratesticular adrenal tissue compared to that in normal adrenals. A positive correlation between the androstenedione/DHEA ratio and plasma ACTH levels was observed, suggesting a long term stimulatory effect of ACTH on 3 beta HSD. Angiotensin-II could have an additive effect on ACTH-induced 3 beta HSD activity.

Adrenal Hyperplasia, Congenital↗
PubMed1994

A divine mission: Elizabeth McMaster and the Hospital for Sick Children, Toronto, 1875-92.

Elizabeth McMaster was born in Toronto in 1847. Like certain women of her class she sought meaningful volunteer work outside the home and, in 1875, with great drive, determination, and religious zeal led a committee of women who founded the Hospital for Sick Children, Toronto (HSC). The Ladies Committee managed HSC for 17 years but, when the hospital expanded in 1892, transferred control to a Board of Trustees. McMaster completed a nurse training program in 1891 and then assumed the position of Lady Superintendent. It was through the newly legitimized nursing profession that she sought to maintain her influence in the hospital. However, her career as Lady Suerintendent was short-lived due to irreconcilable differences with John Ross Robertson, Chairman of the Board of Trustees. This preliminary study, based on minutes of the Ladies Committee and HSC annual reports, describes McMaster's role in the early development of HSC. It provides a case study illustrating the active role of women in the late nineteenth-century humanitarian movement and information concerning developments in the hospital care of the sick poor.

Canada↗
PubMed1994

Association of the SS genotype of the L-myc gene and loss of 18q sequences with a worse clinical prognosis in colorectal cancers.

L-myc is a nuclear oncogene which is sometimes activated late in tumourigenesis. Digestion of DNA with EcoRI reveals a simple restriction fragment length polymorphism (RFLP) located in the second intron of L-myc, with allele sizes 10 kb (L-allele) and 6.6 kb (S-allele). Some studies have suggested that the presence of the S-allele in the constitutional DNA of a patient with cancer is associated with a higher risk of metastasis in lung, breast and renal cell carcinomas. The aims of this study were to determine if the S-allele was significantly associated with metastasis and also with inactivation of tumour suppressor genes in colorectal cancer. One hundred and twenty-four Caucasian colorectal cancer patients were studied for L-myc genotype, and a subgroup of these (108) had their tumours examined for allele loss at multiple loci on nine chromosomal arms (1p, 1q, 5q, 8p, 14q, 17p, 17q, 18q, 22q) and for mutations in the 12th codon of K-ras. The percentage of individuals with the SS genotype was 19% (4/21) Dukes Stage A, 19% (10/54) Dukes B, 25% (8/32) Dukes C and 40% (8/20) Dukes D. The trend observed here is significant (P < 0.05, Wilcoxon Rank Sum Test). Also, the SS genotype was significantly more common in individuals whose tumours showed allelic loss on 18q (P < 0.01, Fishers Exact Test). This work suggests that the S-allele of L-myc, or a gene in linkage disequilibrium with it, may modify the development of colorectal cancer.

Adult↗
PubMed1993

Regulation of selective protein degradation in the endoplasmic reticulum by redox potential.

Recent studies show that the endoplasmic reticulum (ER) contains proteases, but it is not understood how these enzymes are regulated. In this report we study the selective ER degradation of the subunits (alpha beta gamma delta epsilon zeta) of the T-cell antigen receptor (TCR). When analyzed in vivo, unassembled subunits of the TCR fail to reach the Golgi apparatus and show a differential sensitivity to degradation after synthesis. The alpha, beta, and delta subunits are degraded rapidly, while gamma, epsilon, and zeta are stable. To study the regulation of proteolysis in more detail, beta, gamma, delta, and epsilon subunits were expressed alone in fibroblasts and their selective degradation analyzed in vitro. The beta and delta chains were degraded in the complete absence of vesicular transport, indicating their degradation in the ER membrane compartment. Proteolysis was unaffected by GTP gamma S (guanosine 5'-O-(thiotriphosphate)), EDTA, or depletion of ATP. The gamma and epsilon subunits were stable under the same in vitro conditions, indicating that the assay reconstituted selective protein degradation within the ER. Furthermore, the results showed that the gamma and epsilon subunits did not escape degradation by being transported from the ER to pre-Golgi, or cis-Golgi, membrane compartments. Structural determinants of ER degradation contained within the membrane anchor of the TCR beta subunit were only active in permeabilized cells when reducing agents were added to the assay. Surprisingly, reducing conditions disrupted the regulation of ER proteolysis and induced rapid ER degradation of the stable CD3 gamma subunit and of a control interleukin 2 receptor chimera. Taken together, the results indicated that the ER membrane compartment regulates the selective degradation of newly synthesized proteins. Importantly, the stability of proteins retained in the ER was highly sensitive to redox conditions. It is possible that the redox buffer within the ER lumen may regulate ER protein degradation in vivo.

Amino Acid Sequence↗
PubMed1993

Phosphorylation of recombinant tau by cAMP-dependent protein kinase. Identification of phosphorylation sites and effect on microtubule assembly.

Tau protein is an integral component of paired helical filaments, a pathological feature of Alzheimer's disease. tau extracted from these filaments displays decreased electrophoretic mobility due to aberrant phosphorylation. Here we show that recombinant human tau can be phosphorylated by cAMP-dependent protein kinase resulting in decreased electrophoretic mobility. Phosphorylation of tau by cAMP-dependent protein kinase caused a 92% decrease in the maximum rate of tau-induced microtubule assembly. The sites of phosphorylation were identified by digesting phosphorylated tau with proteases, separating the peptides by reversed-phase HPLC, and analyzing the isolated peptides by liquid-secondary ion mass spectrometry and solid-phase N-terminal sequencing. Five phosphorylation sites were identified, two of which were located within microtubule binding domains. One site was previously shown to be the sole phosphorylation site for CaM kinase II; phosphorylation at this site by CaM kinase II was sufficient to cause decreased electrophoretic mobility (Steiner, B., Mandelkow, E. M., Biernat, J., Gustke, N., Meyer, H. E., Schmidt, B., Mieskes, G., Soling, H. D., Drechsel, D., Kirschner, M. W., Goedert, M., and Mandelkow, E. (1990) EMBO J. 9, 3539-3544). Thus two different second messenger-dependent protein kinases can phosphorylate tau at the same site and induce a shift in tau mobility like that seen in Alzheimer's disease.

Adenosine Triphosphate↗
PubMed1993

Genomic instability occurs in colorectal carcinomas but not in adenomas.

Genomic instability, as demonstrated by the presence of additional alleles at short tandemly repeated (STR) loci, has recently been observed in colorectal tumours from individuals with hereditary nonpolyposis colorectal cancer (HNPCC), and in some sporadic tumours. These neoplasms have been called replication error positive (RER+). In this study, we confirm the presence of genomic instability in a proportion of unselected colorectal carcinomas but find no evidence of instability in adenomas. We further report replication errors in a tetranucleotide sequence, and in STRs within two tumour suppressor genes. 108 colorectal adenocarcinomas and 46 adenomas were analysed for the presence of variant bands at 4-15 microsatellite markers. Seven (6.5%) of carcinomas were RER+, four of which originated from the proximal colon. Analysis of the adenomas and of matched adenoma-carcinoma and carcinoma-metastatic samples from four patients suggests that the replication errors may occur during the development of carcinomas but are rare in adenomas.

Adenocarcinoma↗