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Biomedical subjects

Y Barak

Publications and source records attributed to Y Barak.

At least 145 records · Page 8Linked to original sources
PubMed1992

Improved fertilization rate in an in vitro fertilization program by egg yolk-treated sperm.

High fertilization and PRs have been achieved by using thawed donor sperm cryopreserved with medium containing EY. The aim of our study was to examine the possible effect of EY on the fertilizing capacity of fresh sperm in an IVF program. Preincubation of spermatozoa in EY for 2 hours at room temperature significantly improved fertilization (P less than 0.001) in couples who had low fertilization rates in previous cycles, whereas no effect was found concerning couples with high fertilization rates.

Egg Proteins↗
PubMed1992

Enhanced response of human circulating erythroid progenitor cells to hGH and to IGF-I in children with insufficient growth hormone secretion.

The response of hematopoietic progenitors to the growth promoting effects of hGH and IGF-I has been documented. In this study, the effects of recombinant hGH and IGF-I on the growth of circulating erythroid burst forming cells (BFU-E) from growth-IGF-I retarded children with insufficient growth hormone secretion (IGHS) were evaluated and compared with values obtained from either children with short stature and normal growth hormone levels (SNGH) or normal donors. Both recombinant hGH and IGF-I had significantly greater stimulatory effects on the growth of BFU-E from the IGHS compared with the SNGH and with the normally growing children. At its optimal concentration of 200 micrograms/L, recombinant hGH had a stimulatory effect on the growth of BFU-E from 11 IGHS children yielding a mean +/- SD value of 2.0 +/- 0.3-fold above the unstimulated controls compared with 1.45 +/- 0.16-fold and 1.36 +/- 0.04-fold stimulation of BFU-E from six SNGH and five normal donors, respectively. Similarly, IGF-I, at its optimal concentration of 0.065 nmol/L (0.5 ng/mL), stimulated IGHS-derived BFU-E growth 1.67 +/- 0.25-fold above unstimulated controls, compared with 1.28 +/- 0.17-fold and 1.3 +/- 0.1-fold stimulation of BFU-E from SNGH and from normal donors, respectively. The hGH- and IGF-I-induced stimulatory effects could be neutralized by their respective specific MAb.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

The effects of halothane, enflurane and isoflurane on the isolated rat heart recovering from cardioplegic arrest.

The direct cardiac effects of volatile anesthetics following cardioplegic ischemia were investigated in isolated, paced rat hearts. In one series of experiments, the hearts were perfused with oxygenated Krebs Henseleit solution for a 15-minute stabilization period and then the effect of the volatile anesthetic was tested. In another series of experiments, after the stabilization period, the hearts were subjected to cardioplegic (KCl 20mEq/L) ischemia at 30 degrees C for 30 minutes and then the effect of the volatile anesthetic was tested. Halothane, enflurane or isoflurane was introduced to the Krebs Henseleit solution at 0.7 and 1.4 minimal alveolar concentration. All the volatile anesthetics decreased myocardial contractility in a dose dependent manner both before and after cardioplegic arrest. Halothane decreased coronary flow, while isoflurane and enflurane increased coronary flow in both the cardioplegic and non-cardioplegic hearts. The influence of the anesthetics was transient and ceased once they were withdrawn. Ischemic cardioplegia did not affect the response to volatile anesthetics.

Animals↗
PubMed1992

Thymic humoral factor-gamma 2, an immunoregulatory peptide, enhances human hematopoietic progenitor cell growth.

Thymus humoral factor-gamma 2 (THF gamma 2), an octapeptide important for T-lymphocyte regulation, was assessed for its effect on the in vitro growth of human hematopoietic progenitor cells. This was achieved using a recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF)-stimulated myeloid cell colony formation (granulocyte-macrophage colony-forming cells, GM-CFC) assay as well as a recombinant erythropoietin (rEpo)-stimulated erythroid burst formation (erythroid burst-forming units, BFU-E) assay. Cells were obtained from bone marrow (BM) and peripheral blood (PB) of normal healthy donors and from patients with suppressed bone marrows. The latter group included aplastic anemia, leukemia, and lymphoma patients and patients with solid tumors who responded to intensive chemotherapy with significant pancytopenia. THF gamma 2 significantly enhanced normal BM and PB GM-CFC and PB BFU-E by 2- to 2.5-fold. This effect was totally dependent on the presence of the respective growth factors, that is, rGM-CSF or rEpo, and was specifically reversed by an anti-THF gamma 2 antiserum. Furthermore, although THF gamma 2-induced enhancement of GM-CFC colony formation was not affected by lymphocyte or monocyte depletion, the augmenting effect of the peptide on BFU-E was completely abrogated in the absence of lymphocytes. THF gamma 2-induced augmented growth of progenitor cells derived from severely suppressed marrows was minimal. However, cells from moderately neutropenic patients with leukemia in remission or with lymphoma under chemotherapy responded to the peptide similarly to cells from normal donors. These results suggest a stimulatory role for THF gamma 2 on human myeloid and erythroid hematopoietic progenitor cells. They also suggest the lymphocyte dependence of BFU-E enhancement and lymphocyte independence of GM-CFC stimulation by THF gamma 2. In the former case the thymus-derived peptide may act through the induction of certain erythroid-enhancing lymphokines.

Adjuvants, Immunologic↗
PubMed1991

The efficiency of cryopreserved semen versus fresh semen for in vitro fertilization/embryo transfer.

The efficiency of cryopreserved donor semen versus fresh donor semen in an in vitro fertilization/embryo transfer programme was evaluated. Thirty-nine in vitro fertilization/embryo transfer cycles were performed using fresh donor semen (group A) and 74 cycles were carried out using cryopreserved semen (group B). All patients underwent a uniform controlled ovarian hyperstimulation using high doses of human menopausal gonadotropins. Oocytes were retrieved transvaginally under ultrasound imaging. Semen (fresh or frozen-thawed) were prepared for insemination by a washing technique. Each ovum was inseminated with 500,000-600,000 motile spermatozoa. No significant difference was noted between the two groups regarding female age, duration of infertility, and number of ova retrieved per aspiration. Even though the fertilization rate in group B was significantly lower than in group A (55.5 +/- 3.8 vs 70.4 +/- 3.5, P = 0.008), pregnancy rates per embryo transfer were similar--39.3 and 38.5%, respectively.

Adult↗
PubMed1991

Nose tapping test inducing a generalized flexor spasm: a hallmark of hyperexplexia.

The present report describes a benign disorder of neonates or young infants presenting with generalized hypertonicity accompanied by brisk muscle stretch reflexes, intermittent clonus, and exaggerated startle response. This condition is termed hyperexplexia, and may be either familial or sporadic. Two affected families are reported: Two sisters and their mother are involved in the first family; in the second family, where the parents are asymptomatic first degree cousins, all three siblings suffer from hyperexplexia of various severity. Nose tapping in infants of affected families induced a uniform reaction of facial twitching accompanied by head extension, and a generalized flexor spasm, all of which may be a hallmark of hyperexplexia. Severely hypertonic infants were treated with small doses of benzodiazepines and improved markedly, all becoming asymptomatic by two years of age. Unnecessary investigation and treatment may be avoided by sufficient awareness of possible hyperexplexia.

Child, Preschool↗
PubMed1991

Human growth hormone and insulin-like growth factor-1 enhance the proliferation of human leukemic blasts.

As the number of long-term survivors of childhood leukemia increases, growth retardation has emerged as a significant complication. Treatment of these children with growth hormone (GH) has been suggested and sporadically implemented. We, therefore, studied the effect of human GH (hGH) and its by-product insulin-like growth factor-1 (IGF-1) on the growth of leukemic cells in vitro. Under serum-free conditions hGH and IGF-1 induced a significant dose-dependent proliferative effect on promyelocytic leukemia (HL60) and Burkitt's lymphoma (Daudi) cell lines. Anti-hGH antibodies negated the stimulatory effect of hGH and anti-IGF-1 serum abrogated the growth-promoting effect enhanced by IGF-1. Similar statistically significant stimulatory properties were found when freshly obtained marrow cells from four of five acute lymphoblastic leukemia (ALL) of childhood and four acute myelogenous leukemia (AML) patients were studied in ALL and AML blast-cell clonogenic assays. ALL colonies increased numerically by 72% (P less than .025) and AML colonies by 92% (P less than .01) in the presence of hGH at concentrations of 2.5 x 10(2) and 3.0 x 10(2) ng/mL, respectively. IGF-1 stimulated ALL and AML blast-colony growth at concentrations ranging from 0.05 to 0.5 ng/mL by up to 105% (P less than .025) and 65% (P less than .03), respectively. Our in vitro data suggest that circulating hGH and IGF-1 may promote leukemic blast cell replication in vivo, and the supplemental administration of hGH to leukemia patients in remission must be carefully monitored for early relapse.

Bone Marrow↗
PubMed1991

Ciprofloxacin inhibits human hematopoietic cell growth: synergism with tumor necrosis factor and interferon.

The cytokines tumor necrosis factor (TNF) and interferon (IFN) induce antiproliferative and cytotoxic activity in a variety of cell types. Ciprofloxacin (CFN)--a new fluoroquinolone antibiotic--has also been described, at high concentrations, to suppress hematopoietic cell growth and to affect cytokine production. This study examines the possible relationship between TNF alpha and IFN gamma, as components of host defense mechanisms, and CFN. To investigate the effect of CFN, either alone or combined with TNF or IFN, on normal human hematopoiesis, we examined in vitro changes in hematopoietic progenitor cell growth. We also studied the effect of CFN on human cytokine production by determining TNF, IFN, and colony-stimulating factor (CSF) production by human mononuclear leukocytes (MNC). Granulocyte and monocyte colony formation (granulocyte-macrophage colony-forming cells, GM-CFC) as well as erythroid burst formation (erythroid burst-forming units, BFU-E) were inhibited only by high nontherapeutic levels of CFN. Lower CFN concentrations, however, were inhibitory in the presence of low, noninhibitory concentrations of human recombinant (r)IFN gamma or rTNF alpha. CFN induced a striking dose-dependent increase in IFN gamma production and a decrease in CSF production by mitogen-stimulated MNC. No effect was observed, however, on TNF production by stimulated MNC. The synergistic inhibition of hematopoietic progenitor cell proliferation, achieved by combining low doses of CFN and of antiproliferative cytokines, may explain the occasional case of leukopenia or anemia observed in infected patients receiving CFN. This effect may also indicate the applicability of such a combination against malignant cell growth.

Cell Division↗
PubMed1990

[Israel national childhood acute lymphoblastic leukemia study].

A national childhood acute lymphoblastic leukemia (ALL) study was initiated in Israel in 1984 with the aim of improving results in difficult aspects of treatment including: high-risk groups, the problems of late relapses, and the effect of cranial irradiation for CNS prophylaxis in leading to late neuropsychiatric sequelae and secondary tumors. Induction of chemotherapy with a combination of 6 drugs (vincristine, cyclophosphamide, cytosine arabinoside, adriamycin, prednisone and L-asparaginase), followed by intensification with methotrexate and L-asparaginase, was introduced in both the usual and the high-risk groups. In a selected group with better prognostic factors, therapy was reduced. In an attempt to minimize the sequelae of CNS prophylactic therapy, cranial irradiation was omitted in half the patients and intrathecal (IT) triple therapy was given instead. Following 2 years of unsatisfactory preliminary results in a very high-risk group (VHR; non-T- and T-cell leukemia with WBC counts of greater than 100,000 and greater than 20,000, respectively), treatment was modified and intensified. Between Nov. 1984 and Feb. 1989, 143 patients were enrolled from 10 hospitals. During follow-up of a median of 2.5 years, there were 32 failures (2 failed remissions, 27 relapsed and 3 died of bleeding and sepsis). 107 patients are alive in first remission and an additional 8 in second and third remissions. By Kaplan-Meier life table analysis, the rates of leukemia-free interval (LFI) and event-free interval (EFI) for 4 years were 60% and 57%, respectively. Improved LFI results of 71% for 4 years were achieved in a group with non-T-cell ALL with WBC less than 100,000 (the largest group, 65% of the patients). In the small "good risk" group (10% of patients), and the T-cell group with WBC less than 100,000, LFI for 4 years were 56% and 54%, respectively. In the VHR group, modification seemed to have improved results: LFI of 41% for 3 years. CNS prophylaxis with IT triple therapy was as effective as cranial irradiation in the standard risk group. In 1 out of 33 children on this protocol a single CNS relapse occurred, as compared to 2 out of 35 matched controls with cranial irradiation. These results warrant extension of IT triple therapy to higher risk groups of childhood ALL. As for systemic treatment, increased up-front high-dose intensive therapy is recommended for all groups with ALL, but with reduction of cumulative dose to minimize late effects.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

[Blood culture for diagnosing juvenile chronic myeloid leukemia; relationship to neurofibromatosis].

During the past 12 years we studied children with unexplained chronic leukocytosis and other findings suggestive of acute or chronic myeloid leukemia (AML; CML). We used cultures in soft agar of peripheral blood for granulocyte-macrophage colony-forming cell (GM-CFC) analysis. Colonies were counted, examined morphologically and cytochemically and the findings in patients were compared with those in normal children and patients with leukemoid reactions. 2 children with confirmed CML and neurofibromatosis (NF) were similarly evaluated. Additional studies in 1 of them and in his mother who had NF, included establishment of fibroblast and blood cultures from affected skin and tumor, and stimulation of normal bone marrow-derived GM-CFC by these fibroblasts and the conditioned medium (CM) from these cultures. Growth of GM-CFC from blood cultures of CML and AML patients was significantly enhanced in comparison with blood cultures from normal donors, or patients with other myeloproliferative disorders or leukemoid reactions. Enhanced GM-CFC growth-supportive activity was obtained from CML-NF skin and tumor culture CM in comparison with CM from normal fibroblasts. These results indicate the diagnostic value of blood culture GM-CFC in juvenile CML, and its usefulness in differentiating between CML and other disorders involving leukocytosis. They suggest a possible connection between NF foci and the enhanced proliferation of blood GM-CFC in CML.

Child↗
PubMed1990

The establishment of an ovum donation program using a simple fixed-dose estrogen-progesterone replacement regimen.

Most ovum donation (OD) programs involve cycle synchronization between recipient and donor for normally cycling recipients and a complex estrogen-progesterone replacement regimen for recipients with ovarian failure. In 1987, Serhal and Craft (1) suggested the use of a fixed-dose estrogen-progesterone regimen for recipients who were normally ovulatory and to those with ovarian failure. Following this protocol, and simplifying it still, the authors administered 6 mg estradiol valerate (E2) daily orally starting on day 2-6 of induced withdrawal bleeding, augmented with 100 mg progesterone in ethyl oleate (P) intramuscularly daily, starting any time between 4 days prior to and the day of oocyte pickup. All recipients underwent embryo transfer at a 2-pronuclei (2PN)-10-cell stage. A group of 21 patients underwent 26 treatment cycles, resulting in 16 pregnancies. Twelve of the patients gave birth, one to triplets, two to twins, and nine to singletons. Four patients miscarried in the first trimester of pregnancy.

Adult↗
PubMed1990

Once-daily intramuscular ceftriaxone in the outpatient treatment of severe community-acquired pneumonia in children.

Ceftriaxone, a broad spectrum third-generation cephalosporin with a half-life of six to eight hours, was evaluated prospectively in 147 children with severe community-acquired bacterial pneumonia during the period 11/15/88-5/15/89. Thirty-nine of the children had been unsuccessfully treated with vanous oral antibiotics prior to admission [corrected]. All the patients were initially hospitalized and started on once a day intramuscular ceftriaxone. Mean duration of ceftriaxone therapy was five days. Pathogens were recovered from blood cultures of 17 (11.6%) patients and included S. pneumoniae (13 patients), H. influenzae (three, all resistant to ampicillin) and S. viridans (1) [corrected]. All isolates were sensitive to ceftriaxone. An additional patient had L. pneumophila diagnosed by serology. Cure was achieved in 142 (96.6%) patients; improvement was usually observed within 24-48 hours. After 48 hours, 121 (82.2%) children could be discharged and continued the therapy on ambulatory basis. Based on previous experience we estimated that 383 hospitalization days were saved. No serious side effects were observed. Five patients were considered therapeutic failures; two of them developed empyema and one of them required repeated drainage procedures. A third patient experienced a relapse of pneumonia shortly after completion of therapy. The other two remained febrile for more than seven days; their subsequent improvement was unrelated to the antibiotic therapy, suggesting a viral or mycoplasmal syndrome. Our data suggest that once daily intramuscular ceftriaxone can be successfully used for the outpatient treatment of most community-acquired severe bacterial pneumonias in children. In our opinion it represents the treatment of choice for patients who failed treatment with other antimicrobials and are clinically stable enough not to require hospitalization.

Adolescent↗
PubMed1989

Bovine olfactory cilia preparation: thiol-modulated odorant-sensitive adenylyl cyclase.

We have characterized the adenylyl cyclase activity in a newly developed preparation of isolated olfactory cilia from the bovine chemosensory neuroepithelium. Like its counterparts from frog and rat, the ciliary enzyme was stimulated by guanine nucleotides, by forskolin, and by a variety of odorants in the presence of GTP. The main difference between the bovine olfactory cilia preparation and the frog and rat olfactory cilia preparation is that odorant stimulation of the bovine olfactory adenylyl cyclase is strongly inhibited by submillimolar concentrations of dithiothreitol. This inhibition is a consequence of a concomitant increase in the GTP-stimulated level and the decrease of the odorant stimulation of the enzyme. Nasal respiratory cilia have a much lower level of adenylyl cyclase activity and show no odorant stimulation. Owing to the large quantities of material available, the bovine olfactory cilia preparation is advantageous for studies of the proteins involved in chemosensory transduction.

Adenylyl Cyclases↗
PubMed1989

Congenital dysgranulopoietic neutropenia in two siblings: clinical, ultrastructural, and in vitro bone marrow culture studies.

Two siblings with congenital neutropenia are reported. The first patient, female, died after Pseudomonas sepsis. The second patient male, suffered from recurrent pyogenic infections, with a more benign course. Bone Marrow (BM) and Peripheral Blood (PB) analysis in the second patient revealed a reduced number of granules and myelin bodies in the PB neutrophils, suggesting a developmental defect of primary and secondary granules. BM promyelocytes were almost normal, but the myelocytes and metamyelocytes showed defective granulogenesis. The BM in vitro granulocyte-macrophage-colony-forming cell (GM-CFC) growth and the PB white blood cells (WBC) granulocyte-macrophage-colony-stimulating factor (GM-CSF) production, which were analyzed in the second patient, showed normal numbers of GM-CFC, with differentiation mostly toward monocytes and a defect in the GM-CSF production capacity. The second patient's PB mononuclear cells or serum did not inhibit normal GM-CFC when added to control BM cells. We suggest that in this specific form of congenital neutropenia, which is probably an autosomal recessive disorder, the abnormal neutrophil granule production and the defective provision of GM-CSF by PB WBC are unique pathognomonic characteristics, possibly associated with the overt neutropenia.

Agranulocytosis↗