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M Amit

Publications and source records attributed to M Amit.

At least 19 recordsLinked to original sources
PubMed2004

Derivation of a diploid human embryonic stem cell line from a mononuclear zygote.

BACKGROUND: IVF occasionally produces aneuploid zygotes with one or three pronuclei (PN). Routinely, these zygotes are discarded. The aim of this work was to establish human embryonic stem cell (hESC) lines from blastocysts resulting from abnormal fertilization. METHODS: Abnormally fertilized zygotes were cultured to the blastocyst stage and, following zona pellucida digestion, zona-free blastocysts were placed on a mouse feeder layer. Culture of hESCs was carried out as described earlier. RESULTS: Six out of the nine developing blastocysts attached to the feeder layer. One hESC line, originating from a mononuclear zygote following ICSI, was successfully derived. This line displayed typical phenotype and embryonic surface markers, and exhibited the potential to develop into all three embryonic germ layers both in vitro (by embryoid body formation) and in vivo (teratoma generation). Genetic examination revealed normal diploid karyotype and heterozygotic appearance for metachromatic leukodystrophy (MLD). CONCLUSION: This method, which requires neither immuno nor mechanical removal of the trophectoderm, may facilitate the derivation of hESC lines in general, and those from abnormal embryos in particular. Furthermore, it is shown that aneuploid zygotes can be used as a source for normal hESC derivation and hold the potential to generate aneuploid hESC lines for research purposes.

Animals↗
PubMed2004

The effect of spironolactone, cilazapril and their combination on albuminuria in patients with hypertension and diabetic nephropathy is independent of blood pressure reduction: a randomized controlled study.

OBJECTIVE: The effect of spironolactone, cilazapril and their combination on albuminuria was examined in a randomized prospective study in female patients with diabetes and hypertension. PATIENTS AND METHODS: Sixty female diabetic patients aged 45-70 years with blood pressure (BP) 140-180/90-110 mmHg, serum creatinine (sCr) < or = 160 micro mol/l, HbA(1c) < or = 10%, and albuminuria were treated by atenolol 12.5-75 mg/d and hydrochlorothiazide 6.25-25 mg/d. Titration-to-target helped to reach BP values < or = 135/85 mmHg in 46 patients after 12 weeks. These patients were randomized to spironolactone 100 mg/d or cilazapril 5 mg/d for 24 weeks. Then both groups received spironolactone 50 mg/d and cilazapril 2.5 mg/d for 24 weeks. BP was stabilized by tapering the dose of the initial agents. Urinary albumin/creatinine ratio (ACR), BP, K(+). sCr and HbA(1c) were assessed at baseline and at weeks 12, 16, 36 and 60. RESULTS: The average BP at week 12 was 128 +/- 4/81 +/- 3 mmHg and remained constant, in both groups, throughout the study. ACR declined on spironolactone from a median value (range) of 452 (124-1571) to 216 (64-875) mg/g (P = 0.001), and on cilazapril to 302 (90-975) mg/g (P = 0.001). The difference between spironolactone and cilazapril was significant (P = 0.002). Combined treatment resulted in a further modest decline in ACR. Serum creatinine was unaltered by spironolactone and rose slightly (121 to 126 micro mol/l, P = 0.02) on cilazapril. CONCLUSION: At the doses tested, spironolactone was superior to cilazapril in reducing albuminuria. Combined administration was more effective than either drug alone. These effects were independent of BP values. Hyperkalaemia was the main side-effect.

Aged↗
PubMed2003

Feeder layer- and serum-free culture of human embryonic stem cells.

In addition to their contribution to the research on early human development, human embryonic stem (hES) cells may also be used for cell-based therapies. Traditionally, these cells have been cultured on mouse embryonic fibroblast feeder layers, which allow their continuous growth in an undifferentiated state. However, the use of hES cells in human therapy requires an animal-free culture system, in which exposure to mouse retroviruses is avoided. In this study we present a novel feeder layer-free culture system for hES cells, based on medium supplemented with 15% serum replacement, a combination of growth factors including transforming growth factor beta1 (TGFbeta1), leukemia inhibitory factor, basic fibroblast growth factor, and fibronectin matrix. Human ES cells grown in these conditions maintain all ES cell features after prolonged culture, including the developmental potential to differentiate into representative tissues of the three embryonic germ layers, unlimited and undifferentiated proliferative ability, and maintenance of normal karyotype. The culture system presented here has two major advantages: 1) application of a well-defined culture system for hES cells and 2) reduced exposure of hES cells to animal pathogens. The feeder layer-free culture system reported here aims at facilitating research practices and providing a safer alternative for future clinical applications of hES cells.

Animals↗
PubMed2003

Human feeder layers for human embryonic stem cells.

Human embryonic stem (hES) cells hold great promise for future use in various research areas, such as human developmental biology and cell-based therapies. Traditionally, these cells have been cultured on mouse embryonic fibroblast (MEF) feeder layers, which permit continuous growth in an undifferentiated stage. To use these unique cells in human therapy, an animal-free culture system must be used, which will prevent exposure to mouse retroviruses. Animal-free culture systems for hES cells enjoy three major advantages in the basic culture conditions: 1). the ability to grow these cells under serum-free conditions, 2). maintenance of the cells in an undifferentiated state on Matrigel matrix with 100% MEF-conditioned medium, and 3). the use of either human embryonic fibroblasts or adult fallopian tube epithelial cells as feeder layers. In the present study, we describe an additional animal-free culture system for hES cells, based on a feeder layer derived from foreskin and a serum-free medium. In this culture condition, hES cells maintain all embryonic stem cell features (i.e., pluripotency, immortality, unlimited undifferentiated proliferation capability, and maintenance of normal karyotypes) after prolonged culture of 70 passages (>250 doublings). The major advantage of foreskin feeders is their ability to be continuously cultured for more than 42 passages, thus enabling proper analysis for foreign agents, genetic modification such as antibiotic resistance, and reduction of the enormous workload involved in the continuous preparation of new feeder lines.

Cell Differentiation↗
PubMed2001

Human embryonic stem cells can differentiate into myocytes with structural and functional properties of cardiomyocytes.

The study of human cardiac tissue development is hampered by the lack of a suitable in vitro model. We describe the phenotypic properties of cardiomyocytes derived from human embryonic stem (ES) cells. Human ES cells were cultivated in suspension and plated to form aggregates termed embryoid bodies (EBs). Spontaneously contracting areas appeared in 8.1% of the EBs. Cells from the spontaneously contracting areas within EBs were stained positively with anti-cardiac myosin heavy chain, anti--alpha-actinin, anti-desmin, anti--cardiac troponin I (anti-cTnI), and anti-ANP antibodies. Electron microscopy revealed varying degrees of myofibrillar organization, consistent with early-stage cardiomyocytes. RT-PCR studies demonstrated the expression of several cardiac-specific genes and transcription factors. Extracellular electrograms were characterized by a sharp component lasting 30 +/- 25 milliseconds, followed by a slow component of 347 +/- 120 milliseconds. Intracellular Ca(2+) transients displayed a sharp rise lasting 130 +/- 27 milliseconds and a relaxation component lasting 200--300 milliseconds. Positive and negative chronotropic effects were induced by application of isoproterenol and carbamylcholine, respectively. In conclusion, the human ES cell--derived cardiomyocytes displayed structural and functional properties of early-stage cardiomyocytes. Establishment of this unique differentiation system may have significant impact on the study of early human cardiac differentiation, functional genomics, pharmacological testing, cell therapy, and tissue engineering.

Actinin↗
PubMed2001

Insulin production by human embryonic stem cells.

Type 1 diabetes generally results from autoimmune destruction of pancreatic islet beta-cells, with consequent absolute insulin deficiency and complete dependence on exogenous insulin treatment. The relative paucity of donations for pancreas or islet allograft transplantation has prompted the search for alternative sources for beta-cell replacement therapy. In the current study, we used pluripotent undifferentiated human embryonic stem (hES) cells as a model system for lineage-specific differentiation. Using hES cells in both adherent and suspension culture conditions, we observed spontaneous in vitro differentiation that included the generation of cells with characteristics of insulin-producing beta-cells. Immunohistochemical staining for insulin was observed in a surprisingly high percentage of cells. Secretion of insulin into the medium was observed in a differentiation-dependent manner and was associated with the appearance of other beta-cell markers. These findings validate the hES cell model system as a potential basis for enrichment of human beta-cells or their precursors, as a possible future source for cell replacement therapy in diabetes.

Animals↗
PubMed2001

A pilot study of a long acting somatostatin analogue for the treatment of refractory rheumatoid arthritis.

OBJECTIVE: To evaluate the efficacy and safety of a long acting somatostatin analogue in a subset of patients with refractory rheumatoid arthritis (RA). METHODS: Ten patients with active, refractory RA, who had failed to respond to at least four disease modifying antirheumatic drugs (DMARDs), were treated with monthly intramuscular injections of 20 mg of a long acting preparation of octreotide (Sandostatin-LAR) for three months. They were evaluated every two weeks in an open label pilot study. The primary measure of clinical response was the American College of Rheumatology criteria for a 20% improvement in measures of disease activity (ACR 20). RESULTS: Eight patients completed the 14 week trial, while two patients received only one or two doses of the somatostatin analogue, but were eligible for evaluation. On an intention to treat basis 6/10 patients responded: four patients met the ACR 20 criteria at weeks 6-10, while two patients continued to improve with time, and met the ACR 50 and 70 criteria respectively, at week 14. On evaluation of the 10 patients as a group, a significant improvement (p<0.05) was noted in the mean visual analogue scales of pain, doctor's and patient's global assessment of disease activity, and in the mean number of swollen joints. Adverse effects were minor: transient bloating and loose stools, an urticarial rash (n=1), and a transient increase of liver enzymes (n=1). CONCLUSION: Treatment with a long acting somatostatin analogue led to significant clinical improvement in a subset of patients with active, refractory RA. The treatment was relatively safe and well tolerated. Further large, placebo controlled studies are required to evaluate this drug as a potential DMARD for patients with RA.

Adult↗
PubMed2000

Clonally derived human embryonic stem cell lines maintain pluripotency and proliferative potential for prolonged periods of culture.

Embryonic stem (ES) cell lines derived from human blastocysts have the developmental potential to form derivatives of all three embryonic germ layers even after prolonged culture. Here we describe the clonal derivation of two human ES cell lines, H9.1 and H9.2. At the time of the clonal derivation of the H9.1 and H9.2 ES cell lines, the parental ES cell line, H9, had already been continuously cultured for 6 months. After an additional 8 months of culture, H9.1 and H9.2 ES cell lines continued to: (1) actively proliferate, (2) express high levels of telomerase, and (3) retain normal karyotypes. Telomere lengths, while somewhat variable, were maintained between 8 and 12 kb in high-passage H9.1 and H9.2 cells. High-passage H9.1 and H9.2 cells both formed teratomas in SCID-beige mice that included differentiated derivatives of all three embryonic germ layers. These results demonstrate the pluripotency of single human ES cells, the maintenance of pluripotency during an extended period of culture, and the long-term self-renewing properties of cultured human ES cells. The remarkable developmental potential, proliferative capacity, and karyotypic stability of human ES cells distinguish them from adult cells.

Adult↗
PubMed2000

Inactive systemic lupus erythematosus id associated with a normal stimulated Th(1)/Th(2) cytokine secretory pattern.

OBJECTIVES: To determine the Th(1)/Th(2)balance in systemic lupus erythematosus (SLE) patients with inactive disease. METHODS: A comprehensive analysis of peak secretion, overall cytokine production and secretory pattern of Th(1)and Th(2)cytokines from stimulated PBMC of 10 SLE patients with inactive disease and 10 age- and sex-matched controls. RESULTS: No significant differences were found in the peak and total secretion of all cytokines, as well as in the Th(1)and Th(2)secretory patterns and proliferative response between the two groups. CONCLUSION: Th(1)and Th(2) balance in inactive SLE is normal.

Adult↗
PubMed2000

Differentiation of human embryonic stem cells into embryoid bodies compromising the three embryonic germ layers.

BACKGROUND: Embryonic stem (ES) cells are lines of cells that are isolated from blastocysts. The murine ES cells were demonstrated to be true pluripotent cells as they differentiate into all embryonic lineages. Yet, in vitro differentiation of rhesus ES cells was somewhat inconsistent and disorganized. The recent isolation of human ES cells calls for exploring their pluripotential nature. MATERIALS AND METHODS: Human ES cells were grown in suspension to induce their differentiation into embryoid bodies (EBs). The differentiation status of the human ES cells and EBs was analyzed by following the expression pattern of several lineage-specific molecular markers using reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization. RESULTS: Here we report the induction in vitro of cystic embryoid bodies from human ES cells. Our findings demonstrate induction of expression of cell-specific genes during differentiation of the human ES cells into EBs. In the human EBs, we could show a characteristic regional expression of embryonic markers specific to different cellular lineages, namely, zeta-globin (mesoderm), neurofilament 68Kd (ectoderm), and alpha-fetoprotein (endoderm). Moreover, we present a synchronously pulsing embryoid body that expresses the myocardium marker alpha-cardiac actin. In addition, dissociating the embryoid bodies and plating the cells as monolayers results in multiple morphologies, among them cells with neuronal appearance that express neurofilament 68Kd chain. CONCLUSION: Human ES cells can reproducibly differentiate in vitro into EBs comprising the three embryonic germ layers. The ability to induce formation of human embryoid bodies that contain cells of neuronal, hematopoietic and cardiac origins will be useful in studying early human embryonic development as well as in transplantation medicine.

Animals↗
PubMed1999

Decreased expression of the p21ras stimulatory factor hSOS in PBMC from inactive SLE patients.

Expression of the p21 ras protooncogene is reported to be increased in animal models and in patients with SLE. However, the expression of p21ras regulatory elements has not been determined. We determined the expression of p21ras, and its regulatory elements p120-ras-GAP and hSOS, in PBMC of 10 patients with inactive SLE (mean SLEDAI score 1.8+/-0.53) and 10 age- and sex-matched healthy controls. No difference was found between the two groups in the levels of p21 ras (3760+/-513 and 3367+/-335, P=0.25) and ras-GAP (1048+/-261 and 1534+/-247, P=0.11) in patients and controls, respectively. In contrast, levels of hSOS were significantly decreased in patients as compared to controls: 955+/-218 and 2306+/-327, P = 0.002, respectively. The mitogen-induced proliferative response was comparable in the two groups: SI 20.8+/-4.2 and 15.03+/-4.9, P=0.135, in patients and controls, respectively. Taken together, our data demonstrate that nonactive SLE patients are characterized by reduced hSOS expression and underscore the need for a comprehensive evaluation of p21ras pathway in these patients.

Adult↗
PubMed1998

Treatment of staphylococcal septic arthritis in rabbits by systemic antibiotics and intra-articular corticosteroids.

OBJECTIVE: To assess the effect of intra-articular corticosteroids added to systemic antibiotics in experimental septic arthritis. METHODS: Rabbits were injected intra-articularly by Staphylococcus epidermidis. Rabbits received no additional treatment and served as control (group 1), were treated with systemic antibiotics (group 2), or treated with systemic antibiotics and intra-articular corticosteroids (group 3). After 15 days animals were killed and joint histopathological-histochemical parameters were assessed. RESULTS: All rabbits survived the experiment. The treated groups (2-3) had lower histological-histochemical scores in comparison with the untreated group (1). Group 3 had significantly lower scores in joint sections in comparison with group 2: (mean (SD) 6.5 (1.4) v 4.0 (1.0), p = 0.001 and 7.4 (2.6) v 4.2 (2.2), p = 0.01), because of lower damage expressed in clustering of chondrocytes, pannus formation, proteoglycan depletion, and synovitis. CONCLUSION: Addition of local corticosteroids to systemic antibiotics in septic arthritis seems to be harmless, and improves joint histological-histochemical parameters in this experimental setting.

Administration, Topical↗
PubMed1998

Mode of presentation and multisystem involvement in Behçet's disease: the influence of sex and age of disease onset.

OBJECTIVE: To evaluate the correlation between the age at onset of Behcet's disease (BD) and sex distribution, mode of disease appearance, and number of organs involved during the disease. METHODS: BD was defined according to the International Study Group criteria. Data from medical files and from patient interviews were collected. Results were analyzed for children and adults, according to age at disease onset. A systemic involvement index was calculated as the sum of visceral organ systems involved. RESULTS: Fifty-nine patients with BD were studied, 26 male and 33 female. The mean age at disease onset was 8.4 +/- 4.5 years in children and 29.8 +/- 7.9 years in adults. The age of onset was significantly lower in male versus female patients. BD presented in children almost entirely as recurrent aphthous stomatitis, while in adults, less than one-third of patients presented first with oral ulcers. The mean age at disease onset of patients who presented first with oral ulcers was significantly lower than the age of patients presenting first with non-oral aphthosis. The mean systemic involvement index was higher in adult onset than in juvenile onset disease. A significant linear correlation was found between age of disease onset and total number of visceral organ systems involved. CONCLUSION: BD was observed to occur earlier in males than in females. The first manifestation of BD in children is almost exclusively in the form of oral ulcers, while older patients have a large proportion of non-oral aphthosis as their first disease manifestation. Disease onset at an older age is positively correlated with increased disease spectrum.

Adult↗
PubMed1997

Seasonal variations in manifestations and activity of systemic lupus erythematosus.

The purpose of the present study was to investigate a possible seasonal pattern in various clinical and laboratory manifestations in a group of systemic lupus erythamatosus (SLE) patients. One hundred and five SLE patients were followed up during a 4 yr period. Data on each of the clinical and laboratory variables examined, as well as the results of the disease activity index (SLEDAI), were plotted against the month during which they were obtained. Photosensitivity was the only variable to show a seasonal pattern, having higher scores during the summer months (1.04 +/- 0.16 in July vs 0.58 +/- 0.12 in December). We were unable to show seasonal patterns in any of the other variables examined. As a group, SLE patients do not show any significant seasonal pattern in disease manifestations and activity, except for photosensitivity. However, such a pattern may exist for the individual patient.

Adolescent↗
PubMed1996

Expression of rheumatoid arthritis in two ethnic Jewish Israeli groups.

OBJECTIVE: To investigate the expression of rheumatoid arthritis (RA) in Jewish Israeli patients according to ethnic origin. METHODS: RA patients who were seen in a primary public rheumatology clinic were divided into two groups according to ethnic origin (Sepharadic or Askenazi) and subjected to a cross sectional study. The two groups were compared for history, physical status, and radiographic and laboratory variables. The entire study population was again divided into two groups according to formal educational level, and these were also compared for the same variables as above. RESULTS: The patients of Sepharadic origin had significantly more pathological recordings of pain and fatigue, and greater Ritchie scores than those of Askenazi origin. The Sepharadic group patients were younger, had a lower educational level, and were predominantly female. The more educated group recorded significantly less pathological pain and fatigue, and had smaller Ritchie scores. Functional capacity and global disease severity, assessed by physician and patient, were also reduced in the more educated group. On multiple regression analysis, ethnic origin was found to be independently related to functional class. Education was found to be independently related to the Ritchie score. CONCLUSIONS: Disease manifestations in Jewish RA patients of Sepharadic origin are more serious compared with those in patients of Askenazi origin. In addition, low educational level is related to more severe disease manifestations in Israeli RA patients.

Adult↗
PubMed1994

Bacteremia in patients without known underlying disorders.

Of 2030 consecutive patients with bacteremia, only 102 were free from underlying disorders. 43 were males, and the median age was 66 years. The sources of infection were the urinary tract (in 48%), lower respiratory tract (13%), endocarditis (7%), biliary tract (6%) and the meninges (5%). The most common pathogens were Escherichia coli (in 45% of patients), Streptococcus pneumoniae (21%), Staphylococcus aureus (9%) and hemolytic streptococci (9%). Overall mortality rate was 13%, 4% in patients with urinary tract infection and 19% in patients with other sources. Half of the deaths occurred within 2 days of hospitalization, and 75% of them within 4 days. All patients with septic shock and all patients with meningitis died. Other factors related to mortality were residence in a nursing home, low functional capacity, advanced age, high blood urea nitrogen and creatinine and low albumin, and infections caused by Staphylococcus aureus, Neisseria meningitidis and polymicrobial infections. A protective effect of appropriate antimicrobial antibiotic therapy could not be demonstrated. In conclusion, bacteremic patients with no known underlying disorder and source of their infection other than the urinary tract should be given maximum supportive treatment and should be closely watched.

Adult↗