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Biomedical subjects

L Feldman

Publications and source records attributed to L Feldman.

At least 19 recordsLinked to original sources
PubMed2001

Extracellular matrix remodeling in the vascular wall.

The extracellular matrix provides a structural framework essential for the functional properties of vessel walls. The three dimensional organization of the extracellular matrix molecules--elastin, collagens, proteoglycans and structural glycoproteins--synthesized during fetal development--is optimal for these functions. Early in life, the vessel wall is subjected to injury: lipid deposition, hypoxia, enzyme secretion and reactive oxygen species production during inflammatory processes, and the extracellular matrix molecules are hydrolyzed by proteases--matrix metalloproteinases, leukocyte elastase, etc. In uninjured arteries and veins, some proteases are constitutively expressed, but through the control of their activation and/or their inhibition by inhibitors, these proteases have a very low activity. During the occurrence of vascular pathologies--atherosclerosis, hypertension, varicosis, restenosis, etc.--the balance between proteases and their inhibitors is temporally destroyed through the induction of matrix metalloproteinase gene expression or the secretion of enzymes by inflammatory cells. Smooth muscle cells, the most numerous cells in vascular walls, have a high ability to respond to injury through their ability to synthesize extracellular matrix molecules and protease inhibitors. However, the three dimensional organization of the newly synthesized extracellular matrix is never functionally optimal. In some other pathologies--aneurysm--the injury overcomes the responsive capacity of smooth muscle cells and the quantity of extracellular matrix decreases. In conclusion, care should be taken to maintain the vascular extracellular matrix reserve and any therapeutic manipulation of the protease/inhibitor balance must be perfectly controlled, because an accumulation of abnormal extracellular matrix may have unforeseen adverse effects.

Aneurysm↗
PubMed2000

The natural history of incidental renal artery stenosis in patients with aortoiliac vascular disease.

PURPOSE: To examine the association between incidentally discovered renal artery stenosis and deterioration of renal function as determined by the change in serum creatinine concentration over time. SUBJECTS AND METHODS: We performed a retrospective review of consecutive patients who underwent aortography for aortoiliac vascular disease. Angiograms were reviewed for renal artery stenosis, defined as a narrowing of at least 20% compared with adjacent normal renal artery. For patients with at least 180 days of subsequent follow-up, the change in serum creatinine concentration per year was compared in patients who had or did not have renal artery stenosis. RESULTS: Of the 201 patients, 96 (48%) had some degree of renal artery stenosis in one or both renal arteries, including 53 (26%) who had at least one stenosis > or= 50% and 40 (20%) who had bilateral stenoses. The only clinical predictor of renal artery stenosis was a history of coronary artery disease (odds ratio = 2.0, 95% confidence interval: 1.2 to 3.8, P = 0.001). Among the 174 patients with > or =180 days of follow-up, there was no statistically significant difference (P = 0.88) in the mean change in serum creatinine concentration per year in the 78 patients with renal artery stenosis (0.06+/-0.33 mg/dL per year) as compared with the 96 patients without renal artery stenosis (0.06+/-0.22 mg/dL per year). Grouping the patients by the maximal percentage of stenosis did not reveal any difference in the mean changes in serum creatinine concentration per year. CONCLUSIONS: Although renal artery stenosis is a common incidental finding in patients with atherosclerotic vascular disease, it is an uncommon cause of progressive renal disease.

Aged↗
PubMed2000

Cigarette smoking in multicultural, urban high school students.

PURPOSE: To profile patterns of cigarette use among a multiethnic population of high school students, and identify important factors associated with cigarette use by ethnicity, in order to plan effective health promotion strategies. METHODS: This cross-sectional study involved the completion of a lifestyle questionnaire by 1236 Grade 9-13 students (86% response rate) from 62 randomly selected classrooms in three urban high schools in Toronto. Chi-square analysis of the association between tobacco use and other variables took account of the clustered sample using CSAMPLE in Epi Info. RESULTS: The students self-identified their ethnicity as follows: 388 Canadian, 269 European, 171 East Indian, 137 Asian, 76 West Indian, and 194 "other." Students who identified themselves as Canadians were significantly more likely to be current smokers (29%) than students reporting other ethnicities (13%). There was no apparent increase in smoking rates for immigrants after 2 or more years in Canada. Current drinking, sexual activity, and especially friends smoking was most strongly associated with current smoking for most ethnic groups, although the relative importance of these variables was not identical for all groups. CONCLUSIONS: Prevention programs may benefit from a focus on the influence of peer smoking and on the grouping together of lifestyle factors associated with smoking for students in all ethnic groups in this multicultural city.

Adolescent↗
PubMed2000

Cold agglutinin disease in a patient with uterine sarcoma.

Cold agglutinin disease is a rare clinical scenario. It is usually associated with infection, drug reaction, and hematologic malignancy, such as non-Hodgkin lymphoma or lymphocytic leukemia. We report a case of cold agglutinin disease in a patient with solid-tumor uterine sarcoma. Immunological dysregulation has been proposed as the pathogenesis for this disease. We also summarize recently reported cases of cold agglutinin disease, the underlying conditions, and advances in the management of cold agglutinin disease.

Adrenal Cortex Hormones↗
PubMed1999

Isolation of differentially expressed genes by cloning transcriptionally active DNA fragments.

During studies of erythroid cell growth and differentiation induced by erythropoietin (Epo), we developed a method that allows the identification and isolation of genes based upon their transcriptional activity. Transcriptionally active genomic DNA fragments from Epo-treated cells and control cells are purified from inactive chromatin using mercury affinity chromatography, based on the mechanism that the thiol groups of histone H3 on transcriptionally active chromatin are exposed to the solvent and therefore are easily accessible. Using the purified genomic DNA fragments from the two populations of cells, a subtractive hybridization strategy is used to isolate and clone genes that are differentially expressed in the absence or in the presence of Epo.

Animals↗
PubMed1999

Defective expression of the SHP-1 phosphatase in polycythemia vera.

The SHP-1 phosphatase associates with the receptors for erythropoietin, stem cell factor, and interleukin-3, and negatively regulates the mitogenic signals generated during engagement by their respective ligands. The erythroid progenitors of patients with polycythemia vera are hypersensitive to the mitogenic effects of these growth factors despite the fact that the numbers and binding affinities for their receptors are not increased. To determine whether post-receptor signaling defects may account for growth factor-hypersensitivity in polycythemia vera, we determined the expression of SHP-1 in highly purified erythroid progenitors from polycythemia vera patients. Our data demonstrate that in approximately 60% of the patients, expression of SHP-1 in the colony forming unit-erythroid population is diminished. The decreased expression of the protein may result from a transcriptional defect, as suggested by the diminished SHP-1 mRNA expression in the erythroid progenitors of these patients. Studies to determine the level of maturation of polycythemia vera and normal cells indicated that there was no difference between the two at early colony forming unit-erythroid stage of differentiation although polycythemia vera cells showed retarded differentiation kinetics at late colony forming unit-erythroid stage of differentiation. Furthermore, SHP-1 expression in normal colony forming unit-erythroid demonstrated downregulation of mRNA and protein levels during terminal differentiation, suggesting that its function is required for growth control during the early stages of erythropoiesis. These results indicate an important role for SHP-1 in the regulation of normal human erythroid progenitors and suggest that defective expression of the protein may contribute to the pathogenesis of polycythemia vera.

Cell Differentiation↗
PubMed1999

Effects of a self-management educational program for the control of childhood asthma.

The objective of the present study was to evaluate the effects of a self-management educational program on 29 children between 6 and 14 years old and their parents implemented in an office setting in Venezuela. Children were randomly assigned to experimental and control group. Children's asthma knowledge, self-management abilities, index morbidity, parents' asthma knowledge and management abilities were measured. The program consisted of six sessions of information giving and cognitive-behavioral strategies for the children, and two talks and an informative brochure for the parents. Results of t tests indicate that the experimental group experienced a statistical significant effects on children's asthma knowledge (P < 0.001) and practice of self-management abilities (P < 0.000) and in parents' knowledge (P < 0.008) compared to the control group. The educational Self-management program had a significant impact on the Morbidity Index of the study group at post-test (P < 0.05). Younger children benefited more from the program compared to older ones (P < 0.09). Children's age is highlighted as a critical variable in designing asthma educational programs. Results suggest the effectiveness on these programs independently of the cultural context.

Adolescent↗
PubMed1999

Alcohol use beliefs and behaviors among high school students.

PURPOSE: To identify specific alcohol use beliefs and behaviors among local high school students; to determine whether relationships exist between alcohol use and various sociodemographic and lifestyle behaviors; and to assist in the development and implementation of alcohol abuse prevention programs. METHODS: This cross-sectional study involved the completion of a questionnaire by 1236 Grade 9-13 students (86% response rate) from 62 randomly selected classrooms in three Canadian urban schools. Data analyzed here are part of a larger lifestyle survey. RESULTS: A total of 24% of students reported never having tasted alcohol, 22% have tasted alcohol but do not currently drink, 39% are current moderate drinkers, 11% are current heavy drinkers (five or more drinks on one occasion at least once a month), and 5% did not answer. Reasons stated most often for not drinking were "bad for health" and "upbringing," while reasons stated most often for drinking were "enjoy it" and "to get in a party mood." Student drinking patterns were significantly related to gender, ethnicity, grade, and the reported drinking habits of parents and friends. Older male adolescents who describe their ethnicity as Canadian are at higher risk for heavy drinking than students who are younger or female, or identify their ethnicity as European or Asian. Current heavy drinkers are at higher risk than other students for engaging in other high-risk behaviors such as drinking and driving, being a passenger in a car when the driver is intoxicated, and daily smoking. CONCLUSIONS: Heavy alcohol use in adolescents remains an important community health concern. Older self-described Canadian and Canadian-born male adolescents are at higher risk for heavy drinking. Current and heavy drinking rises significantly between Grades 9 and 12. Students who drink heavily are more likely to drink and drive, to smoke daily, and to have friends and parents who drink alcohol.

Adolescent↗
PubMed1999

Reactivation of chronic Chagas' disease following allogeneic bone marrow transplantation and successful pre-emptive therapy with benznidazole.

This report shows the early detection of reactivation of chronic Chagas' disease (CCd) in a 27-year-old man with chronic myelogenous leukemia undergoing allogeneic bone marrow transplantation (ABMT). Pre-emptive therapy with benznidazole during a period of 7 weeks led to a rapid recovery of the patient, who remains free of parasitemia 2 years after the bone marrow transplantation.

Adult↗
PubMed1999

Escherichia coli O157:H7 outbreak associated with an improperly chlorinated swimming pool.

A cluster of gastrointestinal illnesses, including one case of hemolytic-uremic syndrome and one culture-confirmed Escherichia coli O157:H7 infection, followed a trailer park pool party. We interviewed a cohort of party attendees and park residents. A primary case was defined as the first gastrointestinal illness within a household between 5 July and 20 July in which the titer of IgG antibody to E. coli O157 (if determined) was elevated. Of 51 party attendees and trailer park residents, 18 developed a gastrointestinal illness, including 10 who met the definition of a primary case. Swimming in the pool significantly increased the risk of primary illness (relative risk = 6.3; 95% confidence interval = 1.8-18.9). No other exposure was significantly associated with primary illness, after pool exposure was controlled for. The implicated pool had little to no chlorine added during the period of 4-10 July. This outbreak provides new evidence of the importance of proper pool maintenance in controlling the spread of E. coli O157:H7.

Chlorides↗
PubMed1998

Expansion of clonotypic T-cell populations in the peripheral blood of asymptomatic Gran Chaco Amerindians infected with HTLV-IIB.

Peripheral blood mononuclear cells from asymptomatic HTLV-II-infected and uninfected Gran Chaco Amerindians were analyzed using polymerase chain reaction (PCR) for expansions of T-cell receptor (TCR) V-beta gene clonotypes. Analyses were performed using primer pairs designed to identify expanded T-cell familial clonotypes based on their unique TCR beta gene rearrangements. Of the 30 HTLV-IIB-positive samples tested, five showed evidence of V-beta clonotypic T-cell expansion. Of the five expansions, two were monoclonotypic and the remaining three were oligoclonotypic. In comparison, 30 HTLV-II-negative Amerindians showed no evidence of clonotypic T-cell expansion. Amplified DNA from one of the monoclonotypic samples was subsequently cloned and sequenced and was found to have uniform variable/ diversity/joining sequences confirming its unique monoclonal T-cell expansion. This method of detecting clonal TCR beta gene rearrangements has the advantage over traditional Southern blot techniques of being more sensitive and specific even with suboptimal specimens. The prognostic significance of clonotypic T-cell expansion in a group such as the HTLV-II-infected Gran Chaco Amerindians remains to be determined.

Argentina↗