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Biomedical subjects

A Katz

Publications and source records attributed to A Katz.

At least 145 records · Page 8Linked to original sources
PubMed1997

General anaesthesia may improve the success rate of hydrostatic reductions of intussusception.

Intussusception is the most common cause of intestinal obstruction in young children. Hydrostatic enemas result in a successful reduction of intussusception in 50% to 80% of patients. Failure to achieve reduction with hydrostatic enema results in laparotomy, although a frequent finding upon exploration is complete reduction of the intussusception, presumably due to induction of general anaesthesia. Recent paediatric literature suggests that induction of general anaesthesia may improve the success rate of therapeutic hydrostatic enema. We report a difficult case of recurrent intussusception where the induction of general anaesthesia alone did not result in reduction of intussusception, but successful reduction by enema was achieved while the patient was anaesthetized.

Anesthesia, General↗
PubMed1997

Peripartum cardiomyopathy occurring in a patient previously treated with doxorubicin.

We present a 28-year-old primigravida woman in whom congestive heart failure developed 3 months after delivery of a neonate. The patient underwent doxorubicin treatment 10 years previously. The combined cardiotoxicity of prior doxorubicin treatment and pregnancy is considered, and the importance of careful follow-up of cardiac function during pregnancy and postpartum in patients previously treated with doxorubicin is stressed.

Adult↗
PubMed1997

Atrial fibrillation/flutter induced by implantable ventricular defibrillator shocks: difference between epicardial and endocardial energy delivery.

INTRODUCTION: We evaluated the incidence and energy dependence of atrial fibrillation/flutter (AF) induced by implantable ventricular defibrillator shocks in 63 patients tested in the operating room or electrophysiology laboratory. METHODS AND RESULTS: Defibrillator shocks were epicardial monophasic in 32 patients, and through an Endotak lead endocardial monophasic in 19 and biphasic in 12 patients. The epicardial and endocardial patient groups had similar clinical characteristics. A total of 517 defibrillator shocks were given. The epicardial group received 336 total defibrillator shocks and 10 +/- 6 shocks (mean +/- SD) per patient compared with the endocardial group, which received 181 total shocks and 6 +/- 4 defibrillator shocks per patient (P = 0.004). In the epicardial group, AF occurred in 13 (41%) patients and in 17 (5%) of the 336 shocks. No AF was induced with endocardial defibrillator shocks. The epicardial mean energy was 16 +/- 9 J, lower than the endocardial mean energy of 20 +/- 9 J (P < 0.004). In the epicardial monophasic group, energy correlated with AF induction. Each patient received 7 +/- 6 defibrillator shocks < 15 J and 4 +/- 2 shocks > or = 15 J, yet AF occurred in only 2.3% versus 9.6% (P < 0.05) of defibrillator shocks < 15 J and > or = 15 J, respectively. Of note, AF was not induced with energy < 4 J or > 31 J. CONCLUSIONS: In the epicardial configuration, AF induction is energy dependent, with an apparent lower and upper limit of vulnerability. AF induction by defibrillator shocks delivered through an Endotak lead is very rare, possibly related to an apparent upper limit of vulnerability of less energy, avoidance of thoracotomy, or different energy field distribution.

Adult↗
PubMed1997

Differential responses of glycogen synthase to ischaemia and ischaemic contraction in human skeletal muscle.

The importance of metabolic changes associated with contraction in the activation of glycogen synthase (GS) during recovery from exercise in human skeletal muscle has been investigated. Subjects underwent two experimental treatments: 15 s of ischaemic isometric contraction at 66% of maximal force, and 40 min circulatory occlusion. Biopsies were taken from the quadriceps femoris muscle at rest, at the end of each treatment, and 5 min post-treatment. The decreases in phosphocreatine (approximately 50%), and increases in glucose 6-phosphate (approximately 3-fold) and lactate (approximately 8-fold) were similar during contraction and occlusion, indicating similar degrees of anaerobic ATP turnover and glycogen breakdown. Glycogen breakdown during each treatment was estimated to correspond to < 5% of the basal muscle glycogen content. GS fractional activity decreased approximately 10% after contraction and approximately 30% after occlusion (P < 0.05 vs. contraction). During recovery from contraction, GS fractional activity increased to 20% above the rest value, whereas no further change occurred during recovery from occlusion (P < 0.001 vs. recovery from contraction). These data demonstrate that the increase in GS fractional activity during recovery from isometric contraction does not require significant glycogen breakdown during the contraction, and is not a consequence of the measured metabolic changes associated with the contraction.

Adult↗
PubMed1997

Increased tetanic force and reduced myoplasmic [P(i)] following a brief series of tetani in mouse soleus muscle.

Muscle performance is improved after a brief period of exercise (warm-up). One factor that is known to strongly affect force production is the myoplasmic concentration of inorganic phosphate ([P(i)]). Improved performance after warm-up may therefore be due to a reduction of [P(i)]. Herein, we show that after a warm-up protocol (15 tetani at 2-s intervals), tetanic force is increased by approximately 6% (P < 0.05) and [P(i)] is almost halved (P < 0.05) in isolated mouse soleus muscle. A warm-up protocol with longer intervals (15 tetani at 5-s intervals) reduced tetanic force and did not alter [P(i)]. We conclude that a reduction of [P(i)] contributes to the force-potentiating effect of warm-up.

Animals↗
PubMed1997

C-peptide does not alter carbohydrate metabolism in isolated mouse muscle.

The effects of C-peptide on carbohydrate metabolism in isolated mouse soleus muscle were studied. C-peptide, at concentrations up to 1,000 nM, had no effect on [14C]glucose incorporation into glycogen, glycogen synthase activity, or 2-deoxyglucose uptake. These data demonstrate that C-peptide has no direct effect on the measured parameters of carbohydrate metabolism in isolated mouse muscle.

Animals↗
PubMed1997

Nifedipine GITS replacing nifedipine SR: ambulatory blood pressure assessment of efficacy.

The relative efficacy of two formulations of nifedipine, slow release (SR) and gastrointestinal therapeutic system (GITS), to lower blood pressure in hypertensive patients was evaluated in a prospective study. Nifedipine GITS 30 mg/day replaced nifedipine SR, 20 mg b.i.d. in 38 patients, 23 monitored by routine blood pressure measurements and 15 by ambulatory monitoring. Nifedipine GITS achieved a marked reduction in blood pressure with a smaller dose than nifedipine SR: 30 versus 40 mg/day, respectively. It is concluded that patients with hypertension controlled on a twice-daily dose of nifedipine prolonged action can be converted to a lower once-daily dose of nifedipine GITS without experiencing any increase in blood pressure. Tolerability and compliance improved when switching to the GITS formulation.

Adult↗
PubMed1997

Antiproliferative activity to glomerular mesangial cells and receptor binding of a heparin-mimicking polyaromatic anionic compound.

Proliferation of mesangial cells (MC) is a key feature in the pathogenesis of numerous renal diseases involving the glomerulus. Heparin, one of several compounds capable of suppressing MC proliferation, did not prove beneficial in the treatment of human glomerular diseases. In a search for a superior antiproliferative agent, a synthetic polyaromatic "heparin mimicking" compound (RG-13577, polymer of 4-hydroxyphenoxy acetic acid, M(r) approximately 5800), previously reported to inhibit the proliferation of vascular smooth muscle cells, was applied. RG-13577 exhibits approximately 1% of the anticoagulant activity of heparin and is nontoxic in animal experiments. Proliferation of primary rat MC was almost completely inhibited in the presence of 10 to 25 micrograms/ml RG-13577, and 50% inhibition was obtained at 1 to 5 micrograms/ml RG-13577. The cells resumed their normal growth rate after removal of RG-13577 from the culture medium. Under the same conditions, heparin exerted only a small inhibitors effect. RG-13577 inhibited signaling (i.e., tyrosine phosphorylation) and MC proliferation induced by both basic fibroblast growth factor and platelet-derived growth factor. RG-13577 binds to a naturally produced extracellular matrix, and the bound molecule retained its antiproliferative effect toward MC. 14C-Labeled RG-13577 also binds to cultured MC in a specific and saturable manner. Binding of 14C-RG-13577 was reduced by 80 to 90% in the presence of excess unlabeled RG-13577, apolipoprotein E, or lactoferrin, but there was no effect with heparin. Furthermore, the antiproliferative effect of RG-13577 was abolished in the presence of lactoferrin. It is proposed that compound RG-13577 inhibits MC proliferation through neutralization of growth-promoting factors, primarily heparin-binding growth factors, and possibly through binding to specific cell surface receptors, most likely the LDL receptor-related protein. RG-13577 and related polyanionic compounds may be applied to inhibit MC proliferation in glomerular diseases.

Animals↗
PubMed1997

Thrombotic microangiopathy in renal transplant recipients treated with cyclosporin A.

Thrombotic microangiopathy is an uncommon but well described complication of renal transplantation. This study is a review of the case records of 18 patients with biopsy proven post transplant thrombotic microangiopathy, without cellular rejection. There was no single characteristic underlying cause of renal failure in native kidneys. Although only two (11%) patients had undergone previous transplantation, 16 (89%) had panel reactive antibodies (PRA). All patients received prophylactic antilymphocyte globulin, a single patient had cyclosporin A (CSA) at the time of transplant and in 16 patients CSA was introduced when graft function was established. On this protocol 16 (89%) patients had early graft function. All patients developed acute renal failure and 16 (89%) required dialysis. Nine (50%) patients developed hematological abnormalities. All patients were treated aggressively with anti-rejection therapy, CSA was temporarily withdrawn, and 2 (11%) patients received plasmapheresis. Seven (39%) patients lost their grafts. Renal function in the remaining patients recovered to serum creatinine levels ranging from 104 mumol/l to 430 mumol/l (1.2 mg% to 4.8 mg%). All patients with surviving grafts had CSA successfully reintroduced. This study indicates that there is an association between patients who develop posttransplant thrombotic microangiopathy after CSA administration and high PRA levels. The condition appears to respond to anti-rejection therapy and stopping CSA in the majority of cases. The safe reintroduction of CSA suggests that endothelial cell damage in the posttransplant period may be multifactorial and not solely due to CSA therapy.

Adolescent↗
PubMed1997

[Superior vena cava and right atrium thrombosis successfully treated with streptokinase].

The case of a 56 year-old male with acute lymphoid leukemia and no signs of activity for the last four months is reported. He presented with superior vena cava thrombosis caused by a Hickman catheter, and had positive blood cultures for Candida albicans and Staphylococcus epidermidis. Despite adequate antimicrobial therapy, the fever persisted, and the patient was submitted to surgical thrombectomy. One week following the procedure, the fever returned, and thrombosis of the superior vena cava extending to the right atrium was identified by transesophageal echocardiography (TEE). The patient underwent thrombolytic therapy with streptokinase, and no thrombus could be identified in the control TEE. No hemorrhagic or thromboembolic complication occurred. The patient was discharged with oral anticoagulation.

Catheters, Indwelling↗
PubMed1997

Ovarian abscess 15 months after vaginal hysterectomy. A case report.

BACKGROUND: Ovarian abscess is a primary infection of ovarian parenchyma. Since 1869, only 44 cases after vaginal hysterectomy have been reported in the medical literature. The pathophysiology of bacterial infection in these cases is different from the traditional ascending mechanism. CASE: A 28-year-old woman presented with complaints of lower abdominal pain and fever 15 months after transvaginal hysterectomy. Her white blood cell count was 22,700/mm3, with 90% neutrophils. Bimanual examination revealed a tender mass in the cul-de-sac, and computed tomography showed a large, multiloculated pelvic mass. Laparotomy, pathologic examination and microbiologic study confirmed the diagnosis of ovarian abscess. CONCLUSION: Our case represents another rare posthysterectomy ovarian abscess. Most of these cases were managed by surgery and antibiotic treatment.

Abscess↗
PubMed1996

Loss of primitive hematopoietic progenitors in patients with human immunodeficiency virus infection.

A number of hematologic abnormalities, including cytopenias, have been observed in patients with human immunodeficiency virus (HIV) infection. To elucidate their mechanisms, primitive cells from bone marrow aspirates of 21 patients with HIV-1 infection were quantitated by flow cytometry. The mean percentage of CD34+ cells is not significantly altered in HIV-1-infected patients in comparison with HIV-1-seronegative controls. In contrast, two- and three-color immunofluorescence analysis showed that in all HIV-1 samples, most CD34+ cells coexpressed the CD38 antigen. The proportion of HIV-1-derived CD34+ cells that did not express the CD38 antigen was significantly lower (HIV-1+: mean, 1.73%; controls: mean, 14%; P < .0005) than in controls. Moreover, of Thy-1+ cells, the proportion of CD34+ cells was twofold lower in HIV-1-infected patients (HIV-1+: mean, 12%; controls, 25%, P < .0005), which suggests that phenotypically primitive cells are depleted in HIV-1 infection. In vitro functional analysis in long-term cultures of sorted CD34+ cells from seven HIV-1 patients showed that CD34+ cells from HIV-1 patients generated much fewer colonies both in the nonadherent and adherent layers than CD34+ cells from controls after 5 weeks of culture (10-fold and four-fold less, respectively). Precise long-term culture initiating cell (LTC-IC) frequency in the CD34+ cell population was determined in three patients by limiting dilution and was markedly decreased in comparison to that of normal controls (from twofold to > sevenfold decreased). To determine if primitive cells were infected by HIV-1, both methylcellulose colonies generated from long-term culture of CD34+ cells and various CD34+ cell fractions purified by flow cytometry were evaluated for the presence of HIV-1 by polymerase chain reaction (PCR). Progeny from long-term culture was HIV-1-negative in three samples. In addition, using a sensitive PCR technique, the HIV-1 genome could not be detected in CD34+, CD34+/CD38-, and CD34+/CD4+ cells. These data show that hematologic disorders in HIV disease may be the consequence of a deficit of primitive cells. However, direct infection of these cells by HIV-1 does not seem to be responsible for this defect.

ADP-ribosyl Cyclase↗
PubMed1996

Phenotype and function of human hematopoietic cells engrafting immune-deficient CB17-severe combined immunodeficiency mice and nonobese diabetic-severe combined immunodeficiency mice after transplantation of human cord blood mononuclear cells.

In an attempt to understand better the regulation of stem cell function in chimeric immunodeficient mice transplanted with human cells, and the filiation between progenitor cells identified in vitro and in vivo, we assessed the different compartments of hematopoietic progenitors found in the marrow of CB17-severe combined immunodeficiency (SCID) mice (34 mice, 9 experiments) after intravenous injection of 2 to 3 x 10(7) cord blood mononuclear cells. On average 6.3 +/- 4 x 10(5) human cells were detected per four long bones 4 to 6 weeks after the transplant predominantly represented by granulomonocytic (CD11b+) and B lymphoid (CD19+) cells. Twenty five percent of these human cells expressed the CD34 antigen, of which 90% coexpressed the CD38 antigen and 50% the CD19 antigen. Functional assessment of progenitor cells (both clonogenic and long-term culture-initiating cells [LTC-IC]) was performed after human CD34+ cells and CD34+/CD38- cells have been sorted from chimeric CB17-SCID marrow 3 to 10 weeks after intravenous (IV) injection of human cells. The frequency of both colony-forming cells and LTC-IC was low (4% and 0.4%, respectively in the CD34+ fraction) when compared with the frequencies of cells with similar function in CD34+ cells from the starting cord blood mononuclear cells (26% +/- 7% and 7.2% +/- 5%, respectively). More surprisingly, the frequency of LTC-IC was also low in the human CD34+ CD38- fraction sorted from chimeric mice. This observation might be partly accounted for by the expansion of the CD34+ CD19+ B-cell precursor compartment. Despite their decreased frequency and absolute numbers, the differentiation capability of these LTC-IC, assessed by their clonogenic progeny output after 5 weeks in coculture with murine stromal cells was intact when compared with that of input LTC-IC. Furthermore the ratio between clonogenic progenitor cells and LTC-IC was similar in severe combined immunodeficiency (SCID) mice studied 4 weeks after transplant and in adult marrow or cord blood suspensions. Results generated in experiments where nonobese diabetic (NOD)-SCID mice were used as recipients indicate a higher level of engraftment but no change in the distribution of clonogenic cells or LTC-IC. These results suggest that the hierarchy of hematopoietic differentiation classically defined in human hematopoietic tissues can be reconstituted in immunodeficient SCID or NOD-SCID mice.

ADP-ribosyl Cyclase↗
PubMed1996

Characterization of a bipotent erythro-megakaryocytic progenitor in human bone marrow.

The aim of the present study was to determine if the human erythroid (E) and megakaryocytic (MK) lineages were closely linked to the existence of a bipotent burst-forming unit (BFU) E/MK progenitor. In methylcellulose cultures, BFU-E/MK colonies were observed at day 12 and closely resembled mature BFU-E with the exception that the erythroid component was surrounded by MK. These colonies were quite different from the colony forming unit (CFU)-GEMM-derived colonies, which were composed of a larger number of erythroblasts and which developed later in culture. The existence of these bilineage colonies composed of 100 to 1,000 erythroblasts intermingled with a few MK and without granulocytic cells was confirmed by the plasma clot technique and immunoalkaline phosphatase labeling of the MK. To investigate if this bipotent progenitor belonged to the compartment of primitive progenitors, CD34+ marrow cells were subfractionated according to expression of the CD38 antigen. The bipotent BFU-E/MK progenitor as well as a large fraction of MK progenitors were found in the CD34+ CD38+/- or in the CD34+ CD38- cell fractions. Growth of this bipotent BFU-E/MK progenitor required the combination of stem cell factor (SCF), Interleukin-3 (IL-3), and Epo in serum free conditions. Addition of IL-6 had only a marginal effect, whereas megakaryocyte growth and development factor (MGDF) was not an absolute requirement, but slightly increased the plating efficiency of CFU-MK and of BFU-E/MK progenitors when combined with SCF, IL-3, and Epo. In contrast, when these cultures were performed in the presence of 30% fetal calf serum, no BFU-E/MK colonies were observed irrespective of the combination of growth factors used, including the presence of MGDF; however, inclusion of the MS-5 cell line restored the growth of this bipotent progenitor. In contrast, in cultures performed in the presence of human normal or aplastic plasma, MS-5 had only a slight effect on the cloning efficiency but improved MK cytoplasmic maturation and MK size, suggesting that the main effect of MS-5 is to diminish the inhibitory effect of the fetal calf serum on the MK differentiation. The clonal origin of bipotent BFU-E/MK colonies was demonstrated in liquid culture of single CD34+ CD38low cells by immunophenotyping individual clones. At day 12, 30% of the clones contained erythroblasts (glycophorin A+) and some MK (CD41+) without granulocytes (G) or macrophages (M) (CD14+ and CD15+). At day 20, clones containing erythroblasts and MK were rare (5%). In contrast multilineage clones could be frequently detected at this time without passage from BFU-E/MK clones at day 12 to GEMM at day 20. These results suggest that a bipotent BFU-E/MK progenitor may be a nonrandom step in the hierarchical development of stem cells.

ADP-ribosyl Cyclase↗
PubMed1996

Augmented force output in skeletal muscle fibres of Xenopus following a preceding bout of activity.

1. The effect of a brief period of activity on subsequent isometric tetanic force production was investigated in single muscle fibres of Xenopus laevis. 2. Following a train of ten tetani separated by 4 s intervals, tetanic force was significantly augmented by about 10%. The tetanic force augmentation persisted for at least 15 min and then slowly subsided. A similar potentiation was seen following trains of five and twenty tetani. 3. During the period of tetanic force potentiation, tetanic calcium was reduced by more than 30%, and intracellular pH was reduced from 7.15 +/- 0.07 to 7.03 +/- 0.11 (n = 4). 4. Fibre swelling was greatest at 1 min and then subsided over 15-20 min and possibly accounted for a small part of the observed force potentiation. 5. A reduction in the inorganic phosphate (P1) concentration of more than 40% was found in fibres frozen in liquid nitrogen at the peak of force potentiation compared with resting fibres. 6. It is concluded that the augmentation of tetanic force found after a brief preceding bout of activity is due to a reduction in inorganic phosphate. This mechanism may underlie the improved performance observed in athletes after warm-up.

Animals↗
PubMed1996

The outcome of patients with acute myocardial infarction ineligible for thrombolytic therapy. Israeli Thrombolytic Survey Group.

PURPOSE: The aim of this study was to determine the proportion of patients with acute myocardial infarction (AMI) excluded from thrombolytic therapy on a national basis and to evaluate the prognosis of these patients by reasons of ineligibility and according to the alternative therapies that they received during hospitalization. PATIENTS AND METHODS: During a national survey, 1,014 consecutive patients with AMI were hospitalized in all the 25 coronary care units operating in Israel. RESULTS: Three hundred and eighty-three patients (38%) were treated with a thrombolytic agent and included in the GUSTO study. Ineligible patients for GUSTO were treated: (1) without any reperfusion therapy (n = 449), (2) by mechanical revascularization (n = 97), or (3) given 1.5 million units of streptokinase (n = 85) outside of the GUSTO protocol. The inhospital and 1-year post-discharge mortality rates were 6% and 2% in patients included in the GUSTO study; 6% and 5% in those mechanically reperfused; 15% and 10% in those treated with thromoblysis despite ineligibility for the GUSTO trial, and 15% and 13% among patients not treated with any reperfusion therapy. CONCLUSIONS: Ineligibility for thrombolysis among patients with AMI remains high. Patients ineligible for thrombolysis according to the GUSTO criteria, but nevertheless treated with a thrombolytic agent were exposed to an increased risk.

Actuarial Analysis↗
PubMed1996

Focal bacterial nephritis (lobar nephronia) in children.

We report 13 patients with 16 episodes of acute lobar nephronia diagnosed in a prospective study that was conducted among 210 hospitalized children with urinary tract infection. In 30 episodes of urinary tract infection, a hypoechogenic or hyperechogenic lesion was found. Twenty patients underwent computed tomography, and in 16 of them acute lobar nephronia was diagnosed. Evolution to renal abscess occurred in 25%. Prolonged intravenous antibiotic treatment was sufficient in all cases.

Abscess↗