• IMA sites
  • IMAJ services
  • IMA journals
  • Follow us
  • Alternate Text Alternate Text
עמוד בית
Thu, 18.07.24

Search results


May 2004
S. Efrat

Type 1 diabetes mellitus is caused by an autoimmune destruction of pancreatic islet beta cells, leading to insulin deficiency. Beta-cell replacement is considered the optimal treatment for type 1 diabetes, however it is severely limited by the shortage of human organ donors. An effective cell replacement strategy depends on the development of an abundant supply of beta cells and their protection from recurring immune destruction. Stem/progenitor cells, which can be expanded in tissue culture and induced to differentiate into multiple cell types, represent an attractive source for generation of cells with beta-cell properties: insulin biosynthesis, storage, and regulated secretion in response to physiologic signals. Embryonic stem cells have been shown to spontaneously differentiate into insulin-producing cells at a low frequency, and this capacity could be further enhanced by tissue culture conditions, soluble agents, and expression of dominant transcription factor genes. Progenitor cells from fetal and adult tissues, such as liver and bone marrow, have also been shown capable of differentiation towards the beta-cell phenotype in vivo, or following expression of dominant transcription factors in vitro. These approaches offer novel ways for generation of cells for transplantation into patients with type 1 diabetes.

November 2003
N. Tweezer-Zaks, E. Shiloach, A. Spivak, M. Rapoport, B. Novis and P. Langevitz
October 2003
A. Figer, T. Friedman, A.E. Manguoglu, D. Flex, A. Vazina, I. Novikov, A. Shtrieker, A.A. Sidi, T. Tichler, E. Even Sapir, J. Baniel and E. Friedman

Background: The precise genes involved in conferring prostate cancer risk in sporadic and familial cases are not fully known.

Objectives: To evlauate the genetic profile within several candidate genes of unselected prostate cancer cases and to correlate this profile with disease parameters.

Methods: Jewish Israeli prostate cancer patients (n=224) were genotyped for polymorphisms within candidate genes: p53, ER, VDR, GSTT1, CYP1A1, GSTP1, GSTM1, EPHX and HPC2/ELAC2, followed by analysis of the genotype with relevant clinical and pathologic parameters.

Results: The EPHX gene His113 allele was detected in 21.4% (33/154) of patients in whom disease was diagnosed above 61 years, compared with 5.7% (4/70) in earlier onset disease (P < 0.001). Within the group of late-onset disease, the same allele was noted in 5.5% (2/36) with grade I tumors compared with 18% (34/188) with grade II and up (P = 0.004). All other tested polymorphisms were not associated with a distinct clinical or pathologic feature in a statistically significant manner.

Conclusions: In Israeli prostate cancer patients, the EPHX His113 allele is seemingly associated with a more advanced, late-onset disease. These preliminary data need to be confirmed by a larger and more ethnically diverse study.

November 2002
Avi Katz, MD, David J. Van-Dijk, MD, Helena Aingorn, PhD, Arie Erman, MD, Malcolm Davies, MD, David Darmon, MD, Hagit Hurvitz, MD and Israel Vlodavsky, PhD

Background: Decreased heparan sulfate proteoglycan content of the glomerular basement membrane has been described in proteinuric patients with diabetic nephropathy. Heparanase is an endo-b-D-glucuronidase that cleaves negatively charged heparan sulfate side chains in the basement membrane and extracellular matrix.

Objectives: To investigate whether urine from type I diabetic patients differs in heparanase activity from control subjects and whether resident glomerular cells could be the source of urinary heparanase.

Methods: Using soluble 35S-HSPG[1] and sulfate-labeled extracellular matrix we assessed heparanase activity in human glomerular epithelial cells, rat mesangial cells, and urine from 73 type I diabetic patients. Heparanase activity resulted in the conversion of a high molecular weight sulfate-labeled HSPG into heparan sulfate degradation fragments as determined by gel filtration analysis.

Results: High heparanase activity was found in lysates of both epithelial and mesangial cells. Immunohistochemical staining localized the heparanase protein to both glomeruli capillaries and tubular epithelium. Heparanase activity was detected in the urine of 16% and 25% of the normoalbuminuric and microalbuminuric diabetic patients, respectively. Urine from 40 healthy individuals did not posses detectable heparanase. Urinary heparanase activity was associated with worse glycemic control.

Conclusion: We suggest that heparanase enzyme participates in the turnover of glomerular HSPG. Hyperglycemia enhances heparanase activity and/or secretion in some diabetic patients, resulting in the loss of albumin permselective properties of the GBM[2].

________________________

[1] HSPG = heparan sulfate proteoglycan

[2] GBM = glomerular basement membrane

Peter C. Harpel, MD and Nasreen S. Haque, PhD

Chemokines and their receptors play regulatory roles in inflammatory reactions. Lipoprotein(a) is an atherogenic lipoprotein, however the mechanisms of its actions are not defined. Our interest in chemokines and their receptors was stimulated by the finding that incubation of Lp(a)[1] with human umbilical vein endothelial cells produced a conditioned medium that was chemotactic for human monocytes. Since infiltration of monocytes into the vessel wall is an early lesion in atherosclerosis, this finding provided a novel mechanism to explain the relationship between Lp(a) and atherosclerosis. The chemoattractant produced by HUVEC[2] was identified as CCL1/I-309, a CC chemokine previously reported to be secreted by stimulated monocytes/macrophages and T lymphocytes. CCR8, the CCL1 receptor, was identified on endothelial cells, and CCL1 was found to be a chemoattractant for these cells. Most recently we demonstrated functional CCR8 on human vascular smooth muscle cells and found that the Lp(a)-HUVEC conditioned medium is a chemoattractant for these cells. CCL1 increased metalloproteinase-2 production by HUVEC, an activity that enables these cells to remodel the vascular matrix. These studies suggest that CCR8 may play an important role in arterial wall pathology.

_________________________

[1] Lp(a) = lipoprotein(a)

[2] HUVEC = human umbilical vein endothelial cells

Tomas Ganz, PhD, MD

Systemic infection or inflammation causes a decrease in intestinal iron absorption and impairs the release of recycled iron from macrophages. Decreased availability of iron may deny this essential element to invading pathogens and may inhibit their multiplication and other metabolic processes but also results in anemia of chronic disease. This article reviews recent discoveries that shed light on the regulation of iron metabolism during infection and iron overload, and point to the central role of a newly discovered peptide, hepcidin. Evidence to date indicates that hepcidin is a negative regulator of intestinal iron absorption, placental iron transport, and the release of iron from macrophages that recycle iron from senescent red cells. It may also be the central mediator of iron sequestration during infections and inflammatory states and the mediator of anemia of chronic disease. Rapid progress in this area is a good example of the beneficial effects of improvements in peptide analysis and chemistry, advances in genomics, and the increasing use of transgenic mice to determine the function of newly discovered genes and proteins.

Pesach. J. Shteper, MSc and Dina Ben-Yehuda, MD
October 2002
Arie Figer, MD, Yael Patael Karasik, MD, Ruth Gershoni Baruch, MD, Angela Chetrit, MSc, Moshe Z. Papa, MD, Revital Bruchim Bar Sade, MSc, Shulamith Riezel, MD and Eitan Friedman, MD, PhD

Background: Genes that confer mild or moderate susceptibility to breast cancer may be involved in the pathogenesis of sporadic breast cancer, modifying the phenotypic expression of mutant BRCA1/BRCA2 alleles. An attractive candidate is the insulin-like growth factor I, a known mitogen to mammary ductal cells in vivo and in vitro, whose serum levels were reportedly elevated in breast cancer patients.

Objective: To evaluate the contribution of the IGF-1 gene polymorphism to breast cancer risk by genotyping for a polymorphic allele size in breast cancer patients and controls.

Methods: We analyzed allele size distribution of the polymorphic CA repeat upstream of the IGF-I gene in 412 Israeli Jewish women: 268 women with breast cancer (212-sporadic and 56 carriers of either a BRCA1:or BRCA2 mutation), and 144 controls. Genotyping was accomplished by radioactive polymerase chain reaction of the relevant genomic region and size fractionation on polyacrylamide gels with subsequent auloradiography,

Results: Among women with breast cancer, with or without BRCA germline mutations, 196 and 198 basepair alleles were present in 4.7% (25/536 alleles), compared with 9% (26/288) controls (P = 0.02). This difference was more pronounced and significant in the non-Ashkenazi population. Conversely, the smaller size allele (176 bp) was present in the breast cancer group only {3/536, 0.6%).

Conclusions: The IGF-I polymorphism may serve as a marker for breast cancer risk in the general Jewish population, in particular non-Ashkenazi Jews, but extension and confirmation of these preliminary data are needed.
 

Abraham Benshushan, MD, Avi Tsafrir, MD, Revital Arbel, MD, Galia Rahav, MD, Ilana Ariel, MD and Nathan Rojansky, MD

Background: Although Listeria monocytogenes is widely distributed in nature, it rarely causes clinical infection in previously healthy people. This microorganism. however, may cause severe invasive disease in pregnant women and newborns.

Objectives: To investigate – in our pregnant population – the impact, severity and outcome of listeriosis on both mother and fetus.

Method: The study was carried out at a level III, university two-hospital complex, In a retrospective chart review of 65,022 parturients during a 10 year period (1990-1999), we identified and: evaluated 11 pregnant patients and their offspring with Listeria infection;

Results: Chorioamnionitis with multiple. placental abscesses were observed in all five placentae examined. Clinically 4 of 11 parturients had a cesarean section for fetal distress (36.3%), as compared to the 14% mean CS rate in our general population. Two of 11 had a fate abortion (18.1%), as compared with the 4% rate in our hospital. Four of 11 had premature labor (36%), which was about four times the rate in our population. Finally, although no intrauterine feta1 death was recorded in our series, there was one neonatal death of a term infant. (1/11, 9%), which is about 10 times higher than our corrected perinatal mortality rate.

Conclusions: If not promptly and adequately treated, listeriosis in pregnancy may present serious hazards to the fetus and newborn through direct infection-of the placenta and chorioamnionitis.
 

Hannah Tamary, MD, Raanan Bar-Yam, BSc, Michal Zemach, MD, Orly Dgany, PhD, Lea Shalmon, MSc and Isaac Yaniv, MD

Fanconi anemia is a rare autosomal recessive disorder characterized clinically by congenital abnormalities, progressive bone marrow failure, and a predisposition to malignancy. FA cells are sensitive to DNA cross-linking agents. Complementation analysis of FA cells using somatic cell fusion has facilitated the identification of eight complementation groups, suggesting that FA is a genetically heterogeneous disorder. Six genes (FANCA, FANCC, FANCD2, FANCE, FANGF, FANCG) have been cloned so far. The majority of affected patients belong to FA group A. Of the 32 unrelated Israeli patients with FA that we studied, 6 carried the FANCC mutations and 15 the FANCA mutations. Among the Jewish patients, ethnic-related mutations were common. Recent cumulative evidence suggests that the FA proteins are repair proteins. FANCC, FANCA and FANCG bind and interact in a protein complex found in the cytoplasm and nucleus of normal cells. FANCD2 exists in two isoforms; the long active form, FANCD2-L, is absent from FA cells of all complementation groups. FANCD2 co-localized with BRCA1 in unclear foci, probably as part of a large genomic surveillance complex. Studies using FANCA and FANCC knockout mice suggest that bone marrow precursors express interferon-g hypersensitivity and show progressive apoptosis. The definition of the molecular basis of FA in many affected families now enables prenatal diagnosis.

April 2002
Rosalia Smolyakov, MD, Klaris Riesenberg, MD, Francisc Schlaeffer, MD, Abraham Borer, MD, Jacob Gilad, MD, Nechama Peled, MSc and Michael Alkan, MD
March 2002
Anna Villa, MD, Christina Sobacchi, PhD and Paulo Vezzoni, MD, PhD

Severe combined immunodeficiencies represent a heterogeneous group of hereditary defects of the immune system that affect both T and B cells and whose etiology has only recently begun to be understood. A portion of these SCID patients bear a defect in either of the two recombination-activating genes, Rag-1 or Rag-2, while others have mutations in a newly identified gene, Artemis. Omenn syndrome is an unusual severe immunodeficiency with T cells but no B cells, and peculiar features also due to a defect in Rag-1 or Rag-2 genes. All these three forms are characterized by an impairment of the VDJ recombination, the process that insures the somatic diversification of immunoglobulin and T cell receptor-encoding genes. Recent findings have enabled us to better understand the pathophysiology of these three immunodeficiencies, which affect the V(D)J recombination process to a different extent and in different ways.

Legal Disclaimer: The information contained in this website is provided for informational purposes only, and should not be construed as legal or medical advice on any matter.
The IMA is not responsible for and expressly disclaims liability for damages of any kind arising from the use of or reliance on information contained within the site.
© All rights to information on this site are reserved and are the property of the Israeli Medical Association. Privacy policy

2 Twin Towers, 35 Jabotinsky, POB 4292, Ramat Gan 5251108 Israel