Israel Medical Association Journal

Polyubiquitylation of cellular proteins has long been recognized as a prelude to a degradative fate in proteasomes. In recent years, however, ubiquitin conjugation has emerged as a regulatory strategy of considerable versatility. Most notably, monoubiquitylation is attributed an intimate role in trafficking of membrane proteins between various cellular compartments. Diverse classes of transmembrane proteins from across the eukaryotic spectrum (e.g., epidermal growth factor-receptor and other receptor tyrosine kinases) become modified with monoubiquitin molecules. Monoubiquitylation of substrates, in turn, regulates both their endocytosis at the plasma membrane and sorting in endosomes for delivery to lysosomes or vacuoles. A mechanistic rationale lies in the identification of a growing list of ubiquitin-binding domains carried by a variety of endocytic adaptor proteins. Thus, ubiquitin-conjugated membrane proteins may form extensive contacts with the endocytic machinery. Further, ubiquitin-binding adaptors and other endocytic components are, likewise, often monoubiquitylated. In this case, ubiquitin conjugation may serve to enhance intermolecular avidity in cargo-bound endocytic complexes, or alternatively, to mediate timely inactivation of ubiquitin-binding adaptors. Interestingly, the ubiquitin/endocytosis interface is appropriated by pathogenic organisms, for instance, during budding of viruses from host-infected cells. Moreover, compromised ubiquitin-mediated transport of certain signaling receptors is associated with disease states, including oncogenic transformation.

Diabetic retinopathy is one of the leading causes of blindness worldwide.

Background: Laron Syndrome, first described in Israel, is a form of dwarfism similar to isolated growth hormone deficiency caused by molecular defects in the GH[1] receptor gene.

Objective: To characterize the molecular defects of the GH-R[2] in Laron syndrome patients followed in our clinic.

Methods: Of the 63 patients in the cohort, we investigated 31 patients and 32 relatives belonging to several ethnic origins. Molecular analysis of the GH-R gene was performed using the single strand conformation polymorphism and DNA sequencing techniques.

Results: Eleven molecular defects including a novel mutation were found. Twenty-two patients carried mutations in the extracellular domain, one in the transmembrane domain, and 3 siblings with typical Laron syndrome presented a normal GH-R. Of interest are, on one hand, different mutations within the same ethnic groups: W-15X and 5, 6 exon deletion in Jewish-Iraqis, and E180 splice and 5, 6 exon deletion in Jewish-Moroccans; and on the other hand, identical findings in patients from distinct regions: the 785-1 G to T mutation in an Israeli-Druze and a Peruvian patient. A polymorphism in exon 6, Gly168Gly, was found in 15 probands. One typical Laron patient from Greece was heterozygous for R43X in exon 4 and heterozygous for Gly168Gly. In addition, a novel mutation in exon 5: substitution of T to G replacing tyrosine 86 for aspartic acid (Y86D) is described.

Conclusions: This study demonstrates: a) an increased focal incidence of Laron syndrome in different ethnic groups from our area with a high incidence of consanguinity; and b) a relationship between molecular defects of the GH-R, ethnic group and geographic area.

Background: Drains are inserted in the dissected axilla of most patients during surgery for breast cancer.

Objective: To evaluate the presence and prognostic value of MUC1 and Met-HGF/SF in the axillary drainage of these patients.

Methods: The study group included 40 consecutive patients with invasive ductal carcinoma of the breast who were suitable for breast-conserving treatment; 20 malignant melanoma patients found to have negative axillary sentinel lymph node served as the control group. The output of the drains, which had been placed in the axilla during operation, was collected, and the presence of MUC1, Met-hepatocyte growth factor/scatter factor and b-actin were assessed in the lymphatic fluid by reverse transcription-polymerase chain reaction assays. The data were compared to the pathologic features of the tumor and the axillary lymph nodes, and to the estrogen and progesterone receptors status.

Results: RT-PCR[1] assays of the axillary lymphatic drainage were positive for MUC1 and Met-HGF/SF[2] in 15 (37.5%) and 26 (65%) of the patients, respectively. Patients in whom MUC1 and Met-HGF/SF were not found in the axillary fluid had smaller tumors and less capillary and lymphatic invasion, compared to patients with positive assays (P < 0.02 for all these comparisons). The lymph nodes were negative for metastases in all patients with negative assays (P < 0.001). The presence of MUC1 and Met-HGF/SF showed negative correlations with the estrogen and progesterone receptors (P < 0.05).

Conclusion: MUC1 and Met-HGF/SF can be detected in the axillary fluids of patients with breast cancer. The expression of both tumor markers in the axillary drainage is strongly associated with unfavorable tumor features and can be used as a prognostic factor.

Intestinal adaptation is the term applied to progressive recovery from intestinal failure following a loss of intestinal length. The regulation of intestinal adaptation is maintained through a complex interaction of many different factors. These include nutrients and other luminal constituents, hormones, and peptide growth factors. The current paper discusses the role of peptide growth factors in intestinal adaptation following massive small bowel resection. This review focuses on the mechanisms of action of peptide growth factors in intestinal cell proliferation, and summarizes the effects of these factors on intestinal regrowth in an animal model of short bowel syndrome.

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.
 

Ghrelin, a 28 amino acid acylated peptide predominantly produced by the stomach, displays strong growth hormone-releasing activity mediated by the hypothalamus-pituitary GH[1] secretagogue receptors that were found to be specific for a family of synthetic, orally active GH secretagogues. The discovery of ghrelin brings us to a new understanding of the regulation of GH secretion. However, ghrelin is much more than simply a natural GH secretagogue. It also acts on other central and peripheral receptors and exhibits other actions, including stimulation of lactotroph and corticotroph secretion, orexigenia, influences gastroenteropancreatic functions, and has metabolic, cardiovascular and anti-proliferative effects. Knowledge of the whole spectrum of biologic activities of this new hormone will provide new understanding of some critical aspects of neuroscience, metabolism and internal medicine. In fact, GHS[2] were born more than 20 years ago as synthetic molecules, eliciting the hope that orally active GHS could be used to treat GH deficiency as an alternative to recombinant human GH. However, the dream did not become reality and the usefulness of GHS as an anabolic anti-aging intervention restoring the GH/IGF-I[3] axis in somatopause is still unclear. Instead, we now face the theoretic possibility that GHS analogues acting as agonists or antagonists could become candidate drugs for the treatment of pathophysiologic conditions in internal medicine totally unrelated to disorders of GH secretion. 

Background: Previous studies have demonstrated myocardial salvage by basic fibroblast growth factor administration following chronic myocardial ischemia or acute myocardial infarction.

Objectives: To study the effect of bFGF[1] on left ventricular morphometry following coronary occlusion and reperfusion episode in rats.

Methods: bFGF (0.5 mg) or placebo was continuously administered for a period of one week using an implanted osmotic pump. Animals were sacrificed 6 weeks after surgery and myocardial cross-sections were stained with Masson-trichrome and with anti-proliferating cell nuclear antigen antibody.

Results: LV[2] area, LV cavity diameter, LV cavity/wall thickness ratio, and injury size were unchanged compared with control animals. Proliferating endothelial cells were significantly more abundant in injured compared with normal myocardium, but with no differences between animals treated or not treated with bFGF.

Conclusions: One week of systemic bFGF administration following coronary occlusion and reperfusion had no additional effect on LV geometry or cellular proliferation in rats.

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[1] bFGF = basic fibroblast growth factor

[2] LV = left ventricular

Background: Low birth weight has been shown to be strongly related to hypertension in adult life.

Objective: To determine whether blood pressure is higher in children with intruterine growth retardation than in control subjects.

Methods: Blood pressure was measured in 58 children aged 4-6 years with IUGR and in 58 age-matched controls. The control children, whose birth weight was appropriate for gestational age, were also matched for gestational age.

Results: The children with IUGR had significantly higher mean values of systolic (p<0.05) and diastolic blood pressures (p<0.05) and mean arterial pressure (p<0.05). Significant differences in blood pressure values were found between preterm IUGR (n=21) and preterm controls (p<0.05).

Conclusion: These data indicate that children with IUGR may be at higher risk of hypertension already in childhood.

Trophic factors such as nerve and fibroblast growth factors are important modulators of 13 cell physiology. These two factors induce the extension of neurite-Iike processes in primary cultures of adult rat 13 cells. Moreover, both NGF and FGF enhance glucose-induced insulin secretion. Since â cells synthesize NGF and pancreatic islet cells produce FGFs, it is possible that autocrine/paracrine interactions may be major regulators of insulin secretion, and impairment of these interactions could lead to pathological states such as diabetes mellitus.

Background: Growth retardation in childhood was only recently recognized as a prominent feature of Gaucher disease type 1, but there are few data on both the pubertal development and the final outcome of growth and sexual maturation.

Objective: To investigate the natural pattern of growth and puberty in patients with Gaucher disease type 1 and the effect of splenectomy and enzyme replacement therapy.

Methods: We retrospectively analyzed growth and puberty in 57 patients with Gaucher disease type 1; 52 were followed since childhood and/or prepuberty and 42 have reached sexual maturity and final height. In the analysis we considered severity of disease, time of splenectomy, and start of enzyme replacement therapy.

Results: Deceleration of growth at age 3–5 years was observed in 30 of 57 patients followed since early childhood while untreated: height-SDS decreased from -0.34±0.42 at age 0–3 years to -1.93±0.95 (P<0.01) at age 7–10 years and was more pronounced with severe disease. A high prevalence (59.6%) of delayed puberty, which was more frequent with severe disease, was observed in 47 patients followed before and throughout puberty. No primary endocrine pathology was found. All patients, untreated as well as treated, with growth and pubertal delay had a spontaneous catch-up, achieved full sexual maturation, and most (83.3%) reached a final height within the range of parental height–standard deviation score. Splenectomy (partial and/or total) performed in 20 patients while still growing had a beneficial effect on growth, which was temporary in some and did not affect puberty. ERT improved growth in 11 patients who started therapy before puberty, as evidenced by a progressive increase in the height-SDS, and seemed to normalize the onset of puberty.

Conclusions: Growth retardation in childhood and delay of puberty are characteristic of Gaucher disease type 1 and are more frequent with severe disease. There is a spontaneous catch-up later in life and most patients reach a final height within their genetic growth potential. Enzyme replacement therapy apparently normalizes growth and possibly also the onset of puberty.

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ERT = enzyme replacement therapy

SDS = standard deviation score