Biomedical subjects

O Inbar

Publications and source records attributed to O Inbar.

At least 19 recordsLinked to original sources

PubMed2007

The effect of a single aerobic training session on cognitive flexibility in late middle-aged adults.

Research has shown that aerobic exercise enhances cognitive function, specifically executive functions. This study examines the effect of acute aerobic exercise on cognitive flexibility - an executive function - in late middle-aged individuals. Fourteen men and 45 women aged 50 - 64, were randomly assigned to moderate exercise (60 % of heart rate reserve), moderately-intense (70 % of heart rate reserve) exercise, and movie-watching control groups after a maximal exercise test. Prior to and following the exercise or control sessions participants performed two cognitive tasks: the Alternate Uses assessing cognitive flexibility and the Digit Span Forward subtest from the Wechsler Adult Intelligence Scale - Revised assessing attention span. Results indicated significant improvement in Alternate Uses in the exercise groups but not in the control group. No group differences were indicated on the Digit Span. These results provide partial support for the benefit of acute aerobic exercise on cognitive flexibility.

Analysis of Variance↗

PubMed2005

Effect of a short-term graded exhaustive exercise on the susceptibility of serum lipids to oxidation.

The objective of our study was to evaluate the effect of short-term intensive exercise on the susceptibility of serum lipids to ex-vivo peroxidation. We assessed the association between aerobic capacity, serum composition, and serum lipid oxidizability as well as the association between aerobic capacity and the effect of short-term maximal exercise on the kinetics of ex-vivo copper-induced peroxidation of serum lipids. The study involved 30 healthy male volunteers (age 22-39 years, BMI 19.4-29.8). Following 12-hr fasting, blood was withdrawn for determination of blood lipids, LDL, HDL, and TG, and Vitamin E, and for oxidizability assay of the serum lipids. Subsequently, each volunteer underwent an incremental all-out cardiopulmonary exercise stress test (CPET), performed on a motor-driven treadmill (Quinton Q65, USA). The test protocol was a modified Balke protocol. The results of this test were expressed in terms of mass-dependent maximal oxygen uptake (VO2max, ml.kg(-1).min (-1)) and of ventilatory anaerobic threshold (VAT, ml.kg(-1).min(-1)). Immediately after exercise, blood was re-drawn for the determination of serum Vitamin E and for ex-vivo oxidizibility assay, expressed in terms of maximal absorption of oxidation products (OD(max), absorbance units), maximal rate of their production (V(max), OD min(-1)) and the time at which the rate was maximal (t(max), min). Maximal graded exercise had no significant effect on the susceptibility of serum lipids to peroxidation as measured by OD(max) (p = 0.38 at 245 nm, and 0.27 at 268 nm),V(max) (p = 0.34 at 245 nm, and 0.49 at 268 nm) and t(max) (p = 0.17 at 245 nm, and 0.07 at 268 nm). Also no effect was found on the concentration of serum Vitamin E (p = 0.39). Aerobic capacity was not associated either with the susceptibility of serum lipids to ex-vivo peroxidation or with serum Vitamin E concentration. The present findings indicate that a short graded maximal exercise, lasting 8-12 min, is not sufficient to increase the susceptibility of the serum lipids to peroxidation. Thus it may be assumed that the antioxidant capacity of most healthy subjects provides proper protection from a short exhaustive exercise challenge. Also, aerobic capacity in the range represented by our subjects does not seem to influence the susceptibility of serum lipids to peroxidation.

Adult↗

PubMed2005

Prenatal ultrasound diagnosis of club foot: outcome and recommendations for counselling and follow-up.

Club foot was diagnosed by ultrasonography in 91 feet (52 fetuses) at a mean gestational age of 22.1 weeks (14 to 35.6). Outcome was obtained by chart review in 26 women or telephone interview in 26. Feet were classified as normal, positional deformity, isolated club foot or complex club foot. At initial diagnosis, 69 feet (40 fetuses) were classified as isolated club foot and 22 feet (12 fetuses) as complex club foot. The diagnosis was changed after follow-up ultrasound scan in 13 fetuses (25%), and the final ultrasound diagnosis was normal in one fetus, isolated club foot in 31 fetuses, and complex club foot in 20 fetuses. At birth, club foot was found in 79 feet in 43 infants for a positive predictive value of 83%. Accuracy of the specific diagnosis of isolated club foot or complex club foot was lower; 63% at the initial ultrasound scan and 73% at the final scan. The difference in diagnostic accuracy between isolated and complex club foot was not statistically significant. In no case was postnatal complex club foot undiagnosed on fetal ultrasound and all inaccuracies were overdiagnoses. Karyotyping was performed in 25 cases. Abnormalities were noted in three fetuses, all with complex club foot and with additional findings on ultrasound.

Clubfoot↗

PubMed2004

Perceived speech difficulty during exercise and its relation to exercise intensity and physiological responses.

The aim of this study was to establish how ratings of perceived speech production difficulty (PSPD) during exercise of varying intensities are correlated with various physiological responses, in order to determine whether the PSPD is suitable for prescribing exercise training intensity. An incremental running test was performed to establish the subjects' maximal oxygen consumption (VO(2max)) and ventilatory anaerobic threshold (VAT). During the test, the subjects were asked to read a written text. The subjects graded their PSPD at each stage of the test using a 13-level PSPD scale. Throughout the test, various cardiopulmonary parameters were measured breath-by-breath. Regressions of VO(2), heart rate (HR), and pulmonary ventilation (V(E)), all as percentages of their respective measured maximal values, plotted as a function of PSPD showed that the overall associations among those variables are strong and statistically significant ( P<0.05). However, the individual variability within each relative VO(2), V(E) or HR was found to be rather large. The subjects' distribution in relation to their PSPD at the VAT scattered widely across the PSPD scale. These results indicate that estimating exercise intensity by measuring speech difficulty is not valid. Thus it may be assumed that the "talk test", in its present non-standardized form, is a questionable substitute for the anaerobic threshold, HR, or for any other objective physiological measure for prescribing individual training exercise intensity.

Adult↗

PubMed2001

Physiological responses to incremental exercise in patients with chronic fatigue syndrome.

PURPOSE: The purpose of this investigation was to characterize the physiological response profiles of patients with chronic fatigue syndrome (CFS), to an incremental exercise test, performed to the limit of tolerance. METHODS: Fifteen patients (12 women and three men) who fulfilled the case definition for chronic fatigue syndrome, and 15 healthy, sedentary, age- and sex-matched controls, performed an incremental progressive all-out treadmill test (cardiopulmonary exercise test). RESULTS: As a group, the CFS patients demonstrated significantly lower cardiovascular as well as ventilatory values at peak exercise, compared with the control group. At similar relative submaximal exercise levels (% peak VO(2)), the CFS patients portrayed response patterns (trending phenomenon) characterized, in most parameters, by similar intercepts, but either lower (VCO(2), HR, O(2pulse), V(E), V(T), PETCO(2)) or higher (B(f), V(E)/VCO(2)) trending kinetics in the CFS compared with the control group. It was found that the primary exercise-related physiological difference between the CFS and the control group was their significantly lower heart rate at any equal relative and at maximal work level. Assuming maximal effort by all (indicated by RER, PETCO(2), and subjective exhaustion), these results could indicate either cardiac or peripheral insufficiency embedded in the pathology of CFS patients. CONCLUSION: We conclude that indexes from cardiopulmonary exercise testing may be used as objective discriminatory indicators for evaluation of patients complaining of chronic fatigue syndrome.

Adult↗

PubMed2000

The relationship between homology length and crossing over during the repair of a broken chromosome.

Homologous recombination can result in the transfer of genetic information from one DNA molecule to another (gene conversion). These events are often accompanied by a reciprocal exchange between the interacting molecules (termed "crossing over"). This association suggests that the two types of events could be mechanistically related. We have analyzed the repair, by homologous recombination, of a broken chromosome in yeast. We show that gene conversion can be uncoupled from crossing over when the length of homology of the interacting substrates is below a certain threshold. In addition, a minimal length of homology on each broken chromosomal arm is needed for crossing over. We also show that the coupling between gene conversion and crossing over is affected by the mismatch repair system; mutations in the MSH2 or MSH6 genes cause an increase in the crossing over observed for short alleles. Our results provide a mechanism to explain how chromosomal recombinational repair can take place without altering the stability of the genome.

Alleles↗

PubMed2000

Recombination between divergent sequences leads to cell death in a mismatch-repair-independent manner.

Homologous recombination is an important DNA repair mechanism in vegetative cells. During the repair of double-strand breaks, genetic information is transferred between the interacting DNA sequences, thus creating a gene-conversion event. Gene conversion of a functional member of a gene family, which uses an inactive member (such as a pseudogene) as a template, might have deleterious consequences. It is therefore important for the cell to prevent recombination between divergent sequences. We have studied the repair of a double-strand break by recombination in a haploid yeast strain carrying 99% identical alleles located on different chromosomes. The fate of the broken chromosome was followed in the whole cell population without imposing selective constraints. Our results show that all the cells were able to repair the broken chromosome by gene conversion. During the repair, the cells arrest in the cell cycle with a "dumbbell" configuration characteristic of G2/M-arrested cells. Surprisingly, although all the cells repaired the broken chromosome, 60% of them were unable to resume growth and to form colonies after the repair was completed. The low level of cell recovery was due to the 1% divergence between the alleles, but was not dependent on the function of the mismatch-repair system. Cell death, however, could be prevented by the presence of an alternative source of perfect homology located on a different chromosome.

Base Pair Mismatch↗

PubMed2000

Specific inspiratory muscle training in well-trained endurance athletes.

PURPOSE: It has been reported that arterial O2 desaturation occurs during maximal aerobic exercise in elite endurance athletes and that it might be associated with respiratory muscle fatigue and relative hypoventilation. We hypothesized that specific inspiratory muscle training (SIMT) will result in improvement in respiratory muscle function and thereupon in aerobic capacity in well-trained endurance athletes. METHODS: Twenty well-trained endurance athletes volunteered to the study and were randomized into two groups: 10 athletes comprised the training group and received SIMT, and 10 athletes were assigned to a control group and received sham training. Inspiratory training was performed using a threshold inspiratory muscle trainer, for 0.5 h x d(-1) six times a week for 10 wk. Subjects in the control group received sham training with the same device, but with no resistance. RESULTS: Inspiratory muscle strength (PImax) increased significantly from 142.2 +/- 24.8 to 177.2 +/- 32.9 cm H2O (P < 0.005) in the training but remained unchanged in the control group. Inspiratory muscle endurance (PmPeak) also increased significantly, from 121.6 +/- 13.7 to 154.4 +/- 22.1 cm H2O (P < 0.005), in the training group, but not in the control group. The improvement in the inspiratory muscle performance in the training group was not associated with improvement in peak VEmax, VO2max breathing reserve (BR). or arterial O2 saturation (%SaO2), measured during or at the peak of the exercise test. CONCLUSIONS: It may be concluded that 10 wk of SIMT can increase the inspiratory muscle performance in well-trained athletes. However, this increase was not associated with improvement in aerobic capacity, as determined by VO2max, or in arterial O2 desaturation during maximal graded exercise challenge. The significance of such results is uncertain and further studies are needed to elucidate the role of respiratory muscle training in the improvement of aerobic-type exercise capacity.

Adolescent↗

PubMed1999

Homology search and choice of homologous partner during mitotic recombination.

Homologous recombination is an important DNA repair mechanism in vegetative cells. During the repair of double-strand breaks, genetic information is transferred between the interacting DNA sequences (gene conversion). This event is often accompanied by a reciprocal exchange between the homologous molecules, resulting in crossing over. The repair of DNA damage by homologous recombination with repeated sequences dispersed throughout the genome might result in chromosomal aberrations or in the inactivation of genes. It is therefore important to understand how the suitable homologous partner for recombination is chosen. We have developed a system in the yeast Saccharomyces cerevisiae that can monitor the fate of a chromosomal double-strand break without the need to select for recombinants. The broken chromosome is efficiently repaired by recombination with one of two potential partners located elsewhere in the genome. One of the partners has homology to the broken ends of the chromosome, whereas the other is homologous to sequences distant from the break. Surprisingly, a large proportion of the repair is carried out by recombination involving the sequences distant from the broken ends. This repair is very efficient, despite the fact that it requires the processing of a large chromosomal region flanking the break. Our results imply that the homology search involves extensive regions of the broken chromosome and is not carried out exclusively by sequences adjacent to the double-strand break. We show that the mechanism that governs the choice of homologous partners is affected by the length and sequence divergence of the interacting partners, as well as by mutations in the mismatch repair genes. We present a model to explain how the suitable homologous partner is chosen during recombinational repair. The model provides a mechanism that may guard the integrity of the genome by preventing recombination between dispersed repeated sequences.

Aldehyde Oxidoreductases↗

PubMed1997

Cerebral lateral ventricular asymmetry: is this a normal ultrasonographic finding in the fetal brain?

OBJECTIVE: To evaluate the clinical significance of in utero detection of fetal cerebral lateral ventricular asymmetry. METHODS: We used high resolution ultrasonography to study asymmetries of the fetal lateral ventricles in the human brain. A retrospective survey was conducted on 7200 pregnant women who presented at two large district hospitals in Israel. Only fetuses with a difference of greater than 2.4 mm (two standard deviations) in the width of the lateral ventricles, with no known brain pathology, were included in the study. Index cases were evaluated regarding maternal complications, prenatal ultrasound examinations, postnatal imaging studies, and neonatal outcome up to 6 months of age. RESULTS: Lateral ventricular asymmetry was found in 21 subjects, all with available clinical data. In 15 fetuses (71%), the body or the occipital horn of the left lateral ventricle was larger than the right, whereas in six fetuses (29%), the right was larger than the left. In four cases (20%), serial scans noted resolution of asymmetry; in 15 (75%), it was persistent; and in one (5%), asymmetry increased. In one case, termination of pregnancy was performed; however, pathologic examination of the fetal brain failed to detect any structural abnormality. Underlying cerebral pathology was later found only in three fetuses (14%); one had subclinical cytomegalovirus ventriculitis, one had insidious periventricular hemorrhage, and in one fetus with increased asymmetry, trisomy 21 was verified. All the remaining 17 cases had normal neurologic development. CONCLUSIONS: Some degree of asymmetry of the lateral ventricles exists in the human fetal brain and is detectable in utero. Lateral ventricular asymmetry alone is probably not clinically significant, and it may be considered as a normal variant, rather than a pathologic finding.

Adult↗

PubMed1995

Recombination of Ty elements in yeast can be induced by a double-strand break.

The Ty retrotransposons are the main family of dispersed repeated sequences in the yeast Saccharomyces cerevisiae. These elements are flanked by a pair of long terminal direct repeats (LTRs). Previous experiments have shown that Ty elements recombine at low frequencies, despite the fact that they are present in 30 copies per genome. This frequency is not highly increased by treatments that cause DNA damage, such as UV irradiation. In this study, we show that it is possible to increase the recombination level of a genetically marked Ty by creating a double-strand break in it. This break is repaired by two competing mechanisms: one of them leaves a single LTR in place of the Ty, and the other is a gene conversion event in which the marked Ty is replaced by an ectopically located one. In a strain in which the marked Ty has only one LTR, the double-strand break is repaired by conversion. We have also measured the efficiency of repair and monitored the progression of the cells through the cell-cycle. We found that in the presence of a double-strand break in the marked Ty, a proportion of the cells is unable to resume growth.

Base Sequence↗

PubMed1994

Normal cardiopulmonary responses during incremental exercise in 20- to 70-yr-old men.

Healthy men (N = 1424, age 20-70 yr) underwent a progressive incremental treadmill exercise test to volitional maximum. Cardiopulmonary variables were measured breath-by-breath. The aerobic power (VO2max) declined at an average yearly rate of 0.33 ml.kg.-1min-1, HRmax declined 0.685 beats.min-1.yr-1, and max O2 pulse declined at an annual rate of 0.115 ml.beat-1.kg-1*100. Gas exchange threshold (GET) expressed as percentage of VO2max was 58% and 69% in the youngest (20-30 yr) and oldest (61-70 yr) decades, respectively. The average decline in VE, Vt, f, and PETCO2 over the entire age range was 29%, 10%, 21%, and 7%, respectively. There were increases in VE/VO2, and VE/VECO2, from age 20-70 yr of 13% and 14%, respectively, but no changes across 5 decades in PETO2. Physical (height and weight) as well as life-style characteristics (leisure time activity, place of residency, smoking), were found to be potent predictors in most of the cardiopulmonary values at maximal exercise and therefore should be incorporated in the predictive equations for such variables. Normal response patterns of most cardiopulmonary variables throughout the range of exercise intensities were shown to be age-affected and thus should be standardized for age decades.

Adult↗

PubMed1993

Induction of cadmium tolerance in Escherichia coli K-12.

Cadmium ions are bacteriocidal, resulting in exponential killing that starts immediately after exposure. We have shown that pretreatment with sublethal concentrations of cadmium induces cadmium tolerance. Protection against cadmium killing can also be obtained by preincubation at elevated temperatures, known to induce the heat-shock response. However, in contrast to pretreatment at elevated temperatures, exposure to sublethal cadmium concentrations does not induce thermotolerance.

Cadmium↗

PubMed1993

Prevention of fetal loss in experimental antiphospholipid syndrome by low-molecular-weight heparin.

OBJECTIVE: The purpose of this study was to compare the effectiveness of low-molecular-weight heparin with regular heparin in the prevention of fetal resorption in mice with the antiphospholipid syndrome. STUDY DESIGN: Antiphospholipid syndrome was passively induced in ICR mice by injecting them with anticardiolipin antibodies on the first day of pregnancy. Subsequently, these mice were treated with low-molecular-weight heparin in two different doses, with regular heparin, and with a placebo. On gestational day 17 the mice were killed by cervical dislocation, and the pregnancy outcome was evaluated. Statistical analysis was performed by means of a one-way analysis of variance using Bonferroni's t test. RESULTS: Treatment with low-molecular-weight heparin resulted in a resorption rate of 22.4% as opposed to 41.4% in mice with antiphospholipid syndrome that were given regular heparin and 51.7% in nontreated controls. CONCLUSION: We conclude that low-molecular-weight heparin can prevent fetal resorptions in mice with antiphospholipid syndrome.

Animals↗

PubMed1993

In vitro effect of anticardiolipin autoantibodies upon total and pulsatile placental hCG secretion during early pregnancy.

BACKGROUND: The anticardiolipin syndrome is characterized among other features by recurrent thromboembolic events, thrombocytopenia, and recurrent fetal loss associated with high IgG titers of anticardiolipin antibodies and/or the presence of lupus anticoagulant. AIMS: The mechanisms for the fetal loss in this syndrome have not yet been clearly elucidated, although several hypothesis based on experimental data have been put forward. We wanted to evaluated the effect in vitro of anticardiolipin antibodies on the secretion of human chorionic gonadotropin. METHODS: Employing our previous experience with placental explants, we studied the effect of several mouse monoclonal and human polyclonal purified anticardiolipin antibodies (ACA), which were shown by us to induce experimental antiphospholipid syndrome (APLS), to affect the pulsatile secretion of beta human choriogonadotropin. RESULTS: The mouse monoclonal ACA antibodies caused an increase in the pulsatility of beta human choriogonadotropin, while human polyclonal ACA derived from patients with ACA had an inhibitory effect. CONCLUSIONS: These studies with placental explants show that ACA may have an additional effect on placental hormone secretion and thus affect the fate of the embryo.

Abortion, Habitual↗

PubMed1993

The effect of prone immersion on bronchial responsiveness in children with asthma.

We studied the effects of prone immersion on pulmonary function in children with asthma. Twelve children with asthma were subjected to prone immersion (WET) and standing upright on land (DRY) under controlled conditions regarding temperature and relative humidity of the inhaled air, minute ventilation, respiratory frequency, tidal volume, and the concentration of carbon dioxide in the exhaled air. Eight minutes of isocapnic hyperpnea was performed in random order either in the swimming pool (prone) or on land (upright), with the temperature and relative humidity of the inhaled air kept at 20 +/- 2 degrees C and 10 +/- 2%, respectively. The average accumulated ventilation for the 8 min of hyperpnea was 3151 for the WET treatment and 3101 for the DRY (P > 0.1). Average heart rates were 101 +/- 11 and 115 +/- 17 beats.min-1 for the WET and DRY treatments, respectively (P < 0.05). The decrease in FEV1 (delta FEV1) was 26.3 +/- 16.7% after the WET treatment (compared with pretreatment FEV1), and 26.4 +/- 11.3% after the DRY treatment (P > 0.1 between WET and DRY delta FEV1), with similar trend (insignificant differences between treatments), for delta FVC, delta PEF 50%, and delta PEF 25-75%. It is concluded that airway hyperactivity is not alleviated by whole body prone immersion.

Adolescent↗

PubMed1992

Interleukin-3-like activity levels in pregnant women: possible modulation by progesterone.

Human interleukin-3-like activity (IL-3-LA), a factor possessing similar characteristics to interleukin-3 and having clony stimulating factor (CSF) activity, has recently been defined. In the present study, IL-3-LA levels in the sera of women before and after delivery were examined. The results indicate a significant increase in IL-3-LA levels in women before delivery as compared to IL-3-LA levels after delivery or to non-pregnant healthy women. The ability of mononuclear cells from women before and after delivery to produce IL-3-LA was similar to that of mononuclear cells from cord blood. In addition, the effect of progesterone on in vitro IL-3-LA production was examined and a stimulatory dose-dependent effect was observed. These observations point to the hypothesis that during pregnancy IL-3-LA levels are modulated by progesterone. With placental loss, the IL-3-LA in the sera decreases, although the mononuclear cells previously affected by the hormone continue to produce cytokines.

Female↗

PubMed1992

Swimming and asthma. Benefits and deleterious effects.

Swimming is a common pastime activity and competitive sport for patients with asthma. One reason for such popularity may be the low asthmogenicity of swimming compared with landbased activities. Review of available evidence suggests that swimming induces less severe bronchoconstriction than other sports. The mechanisms for this protective effect of swimming are not clear, but there is some experimental evidence intimating that it results in part from the high humidity of inspired air at water level, which reduces respiratory heat loss (and possibly osmolarity of airways mucus). Beneficial roles of horizontal posture and of water immersion have been tested but not confirmed. Swimming poses two potentially deleterious effects to the patient with asthma. One is the exaggerated parasympathetic tone due to the 'diving reflex', that has been shown to trigger bronchoconstriction. The other is airway irritation because of chlorine and its derivatives. Swimming as a training modality has definite benefits for the patient with asthma. These include an increase in aerobic fitness and a decrease in asthma morbidity. There is no conclusive evidence, however, that swim training causes a decrease in the severity or frequency of exercise-induced bronchoconstriction.

Asthma↗