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Biomedical subjects

M Barak

Publications and source records attributed to M Barak.

At least 19 recordsLinked to original sources
PubMed2006

Anisotropic Poisson's ratio and compression modulus of cortical bone determined by speckle interferometry.

Young's modulus and Poisson's ratios of 6mm-sized cubes of equine cortical bone were measured in compression using a micro-mechanical loading device. Surface displacements were determined by electronic speckle pattern-correlation interferometry. This method allows for non-destructive testing of very small samples in water. Analyses of standard materials showed that the method is accurate and precise for determining both Young's modulus and Poisson's ratio. Material properties were determined concurrently in three orthogonal anatomic directions (axial, radial and transverse). Young's modulus values were found to be anisotropic and consistent with values of equine cortical bone reported in the literature. Poisson's ratios were also found to be anisotropic, but lower than those previously reported. Poisson's ratios for the radial-transverse and transverse-radial directions were 0.15+/-0.02, for the axial-transverse and axial-radial directions 0.19+/-0.04, and for the transverse-axial and radial-axial direction 0.09+/-0.02 (mean+/-SD). Cubes located only millimetres apart had significantly different elastic properties, showing that significant spatial variation occurs in equine cortical bone.

Animals↗
PubMed2005

Retrosternal block use in the treatment for dyspnoea.

We present a technique of retrosternal block for symptomatic treatment for dyspnoea of various aetiologies. In our experience with 20 patients, a retrosternal block using lignocaine improved symptoms within minutes. The block was easy to perform and was helpful when the patients' symptoms were not relieved by conventional therapy. Prospective controlled studies are needed to further assess this simple and promising treatment.

Aged↗
PubMed2004

Monochromatic light stimuli during embryogenesis enhance embryo development and posthatch growth.

Photostimulation with green light accelerated BW and muscle development of broilers. In experiment 1, temperature sensors were inserted into 50 broiler eggs. The eggs were placed under 5 green light-emitting diode (LED) lamps at an intensity of 0.1 W/m2 at eggshell level for 5, 10, 15, 20, and 25 min (n = 10). Egg temperatures were recorded continuously. A high correlation was found between lighting period and egg temperature elevation, and an intermittent light regimen of 15 min on and 15 min off was found to eliminate light-induced egg overheating. In experiment 2, the effect of in ovo green light photostimulation on embryonic development was studied. Five hundred fertile eggs were divided into 2 groups: the first was photostimulated with green light from 5 d of incubation until hatch (0.1 W/m2 intensity) and the second was incubated in the dark. In ovo green light photostimulation caused a significant elevation in BW and breast muscle weight during embryo development and posthatch until 6 d of age. In experiment 3, 240 fertile broiler eggs were divided into 2 groups as described in experiment 2. At hatch, chicks from each in ovo light treatment were divided into 2 subgroups: the first was reared under green light and the second under white light. In ovo photostimulation with green light enhanced BW and breast muscle weight. However, rearing under green light did not have any synergistic effect on BW. Collectively, the results suggest that stimulation with green light enhances development and growth in chicks and that the best effect is achieved when this stimulus is provided during incubation.

Animals↗
PubMed2003

Adding a caveat to the urgent clinical notification of anaemia does not reduce inappropriate emergency room referral rates.

BACKGROUND: Urgent clinician notification of low haemoglobin values might influence the clinicians' decision to refer patients to the emergency room (ER). METHODS: We compared the effects of urgent clinician notification for low haemoglobin values with and without an added statement, that an urgent visit to the ER is not required if the patient has a haemoglobin value of 50 g/l or more and is clinically stable. We compared the referral rates and outcomes of 100 consecutive cases reported previously to that of 99 consecutive new cases with the added caveat. RESULTS: Overall 47 (47%) of the historical control patients were referred to the ER compared with 45 (45.5%) in the study group (relative risk, 0.97, 95% CI, 0.72-1.3). Five patients were inappropriately transfused and almost none of the ER visits were an emergency. CONCLUSIONS: Adding a caveat to the urgent clinician notification that anaemia in clinically stable patients is not a medical emergency does not decrease the rate of ER referrals. Further studies are needed in order to find ways to decrease the number of inappropriate ER referrals.

Anemia↗
PubMed2001

The deoxyguanosine kinase gene is mutated in individuals with depleted hepatocerebral mitochondrial DNA.

Mitochondrial DNA (mtDNA)-depletion syndromes (MDS; OMIM 251880) are phenotypically heterogeneous, autosomal-recessive disorders characterized by tissue-specific reduction in mtDNA copy number. Affected individuals with the hepatocerebral form of MDS have early progressive liver failure and neurological abnormalities, hypoglycemia and increased lactate in body fluids. Affected tissues show both decreased activity of the mtDNA-encoded respiratory chain complexes (I, III, IV, V) and mtDNA depletion. We used homozygosity mapping in three kindreds of Druze origin to map the gene causing hepatocerebral MDS to a region of 6.1 cM on chromosome 2p13, between markers D2S291 and D2S2116. This interval encompasses the gene (DGUOK) encoding the mitochondrial deoxyguanosine kinase (dGK). We identified a single-nucleotide deletion (204delA) within the coding region of DGUOK that segregates with the disease in the three kindreds studied. Western-blot analysis did not detect dGK protein in the liver of affected individuals. The main supply of deoxyribonucleotides (dNTPs) for mtDNA synthesis comes from the salvage pathway initiated by dGK and thymidine kinase-2 (TK2). The association of mtDNA depletion with mutated DGUOK suggests that the salvage-pathway enzymes are involved in the maintenance of balanced mitochondrial dNTP pools.

Base Sequence↗
PubMed2001

The role of high-dose oral iron supplementation during erythropoietin therapy for anemia of prematurity.

OBJECTIVE: To assess whether a high intake of oral iron would increase the effect of recombinant human erythropoietin (rHuEPO) on hemoglobin synthesis. METHODS: We studied 30 preterm infants (gestational age 29+/-1.8 weeks, birth weight 1161+/-200 g, at age of 28+/-10 days) who were randomly assigned to receive either 8 mg/kg per day (n=15) or 16 mg/kg per day of oral iron during a course of rHuEPO therapy (900 microg/kg per week) for a duration of 4 weeks. Both groups were comparable in regard to clinical and laboratory data at the time of enrollment. RESULTS: rHuEPO caused a significant increase in reticulocyte count in the low- and high-dose iron groups, 17.1+/-5.3 to 34.7+/-9.2 and 16.3+/-3.3 to 42.5+/-5.6 (10(9)/l), respectively (p<0.05). However, in both groups, hematocrit values remained stable at the end of the study as compared to baseline (0.35+/-0.03% vs. 0.30+/-0.03%, 0.35+/-0.05% vs. 0.30+/-0.03%, NS) and in both groups there was a comparable and significant decrease in ferritin level (259+/-109 to 101+/-40 and 168+/-54 to 69+/-38 microg/l, respectively; p<0.01). The rates of bloody stools without any evidence of necrotizing enterocolitis were not significantly different between the two treatment groups (1/15 vs. 4/15, NS). CONCLUSION: We conclude that a higher dose (16 mg/kg per day) of oral iron is not more beneficial when compared to a lower dose (8 mg/kg per day) during rHuEPO therapy for anemia of prematurity. Further studies will define the optimal dosage and route of administration of iron supplementation during rHuEPO therapy.

Administration, Oral↗
PubMed2001

Reliability of delayed prothrombin time INR determinations in a central laboratory using off-site blood sampling.

A major concern of centralized anticoagulant measurements with off-site sampling is the reliability of international normalized ratio (INR) determinations on blood that may have been taken from the patient hours before the analysis. We compared INR differences in the blood of patients receiving oral anticoagulants after 24 h storage in four conditions: centrifuged at room temperature, centrifuged at 4 degrees C, uncentrifuged at room temperature and uncentrifuged at 4 degrees C. The INR of centrifuged and uncentrifuged blood left at room temperature for 24 h consistently increased by 6% and, after adjustment, there were no misclassifications in the assessment of the adequacy of anticoagulant treatment. Inconsistent changes were noted in tests of refrigerated centrifuged blood. We conclude that storage of blood at room temperature for 24 h results in a consistent prolongation of the prothrombin time, which after correction can reliably be used to adjust the dose of oral anticoagulants.

Anticoagulants↗
PubMed2001

Changes in effective and lethal doses of intravenous anesthetics and lidocaine when used in combination in mice.

We studied the interactions between a local anesthetic agent, lidocaine, and two general anesthetic drugs, propofol and ketamine, in mice. We used two end points: hypnosis, reflected by loss of the righting reflex, and death. The ED50 for hypnosis and the LD50 were determined for each drug separately, and a dose-response curve was prepared for each drug, using combinations of propofol-lidocane and ketamine-lidocaine at three different dose ratios. Probit and isobolographic analyses revealed supra-additive (synergistic) interactions between lidocaine and each of the other anesthetic agents regarding both the effective dose and the lethal dose. No significant difference was found between propofol and ketamine regarding the supraadditive effect.

Anesthetics, Dissociative↗
PubMed2001

Effect of urgent clinician notification of low hemoglobin values.

BACKGROUND: Urgent clinician notification of low hemoglobin values is a common practice. The effect of such notification for samples obtained during an office visit is uncertain. METHODS: We notified the attending physicians in 100 consecutive cases of outpatients with hemoglobin <80 g/L. We reviewed the medical charts of these patients with their personal physicians 1-2 months later. We considered transfusions unnecessary only when given to a clinically stable patient with probable iron deficiency anemia in the absence of chronic diseases that produce the anemia. RESULTS: Overall, 47 (47%) of the patients were referred to the emergency room (ER), and 31 of the 47 (66%) were transfused. Increasing age and decreasing hemoglobin were associated with increased referral of patients to the ER. Six of 31 transfusions were unnecessary. An emergency transfusion was clearly indicated in only 3 of the 31 patients; the other patients were clinically stable. A modified notification strategy excluding microcytic samples >50 g/L would have detected these three patients. Over the follow-up period, no patient not referred to the ER died from complications of anemia, nor were any patients hospitalized with acute symptoms of low hemoglobin. CONCLUSION: In some settings, urgent notification of medical outpatient clinics of patients with hemoglobin <80 g/L may lead to unnecessary ER visits.

Adolescent↗
PubMed2000

The prognostic value of the tumour marker Cyfra 21-1 in carcinoma of head and neck and its role in early detection of recurrent disease.

This study examines a new tumour marker, Cyfra 21-1, as a prognostic marker in predicting the survival of H&N cancer patients, and its correlation with clinical outcome during prolonged follow up of these patients. The study included 67 patients with primary detection of carcinoma of H&N. The survival of these patients was evaluated in correlation with the disease stage and Cyfra 21-1 levels at initial diagnosis. 38 patients were followed clinically and with serial assays for at least 12 months, or until recurrence was diagnosed. Cyfra 21-1 levels were determined periodically, using an Elisa kit. Patients with Cyfra 21-1 < 1.5 ng ml(-1)had a higher survival rate compared to patients with Cyfra 21-1 > or = 1.5 ng ml(-1)(63% vs. 20%, respectively). The risk ratio of Ln(Cyfra 21-1) is 1.62 (P = 0.028). In a Cox regression model that included the disease stage and Ln(Cyfra 21-1), Ln(Cyfra 21-1) was preferred as the main parameter for predicting patients survival. In 83% of the 12 patients with recurrent or residual disease, Cyfra 21-1 was elevated before or during clinical detection of the recurrence. Cyfra 21-1 was found to be a prognostic marker for carcinoma of H&N, unrelated to the stage of the disease. Elevated levels of Cyfra 21-1 without clinical evidence of disease can be attributed to the marker's mean lead-time as compared to the clinical appearance of the disease.

Aged↗
PubMed2000

Early posthatch starvation decreases satellite cell proliferation and skeletal muscle growth in chicks.

The effect of posthatch starvation on skeletal muscle growth and satellite cell proliferation was examined in chicks. Chicks were either fed or starved for 48 h posthatch (d 0-d 2, d 2-d 4 or d 4-d 6) and then refed for 41 d. Body and breast muscle weights were significantly lower in starved chicks than in fed controls throughout the experiment. Histochemical staining revealed that skeletal muscle fiber development in the starved group lagged behind that of the fed group. Starvation from d 2 to 4 and d 4 to 6 posthatch had a progressively lesser effect than did immediate posthatch starvation (P < 0.05). In vitro culturing of breast muscle satellite cells revealed that DNA synthesis and number of cells per gram of muscle in the fed chicks peaked on d 2 and d 3, and then declined. In contrast, DNA synthesis in the cells of starved chicks declined on d 2 and increased on d 3 when chicks were refed. A similar pattern was seen for the number of cells per gram muscle; however, in general cell numbers tended to be higher in the starved group than in controls (P < 0.1). The results obtained with cultured cells were parallel with in situ immunostaining with 5-bromo-2'-deoxyuridine and proliferating cell nuclear antigen in breast muscle from experimental chicks, and with growth hormone receptor expression. These results suggest that satellite cell cultures are a reliable tool for evaluating muscle growth in postnatal chickens. We conclude that sufficient feed in the immediate postnatal period is critical for satellite cell proliferation and skeletal muscle development and is thus important for optimal muscle growth.

Aging↗
PubMed2000

Early postnatal dexamethasone treatment and increased incidence of cerebral palsy.

OBJECTIVE: To study the long term neurodevelopmental outcome of children who participated in a randomised, double blind, placebo controlled study of early postnatal dexamethasone treatment for prevention of chronic lung disease. METHODS: The original study compared a three day course of dexamethasone (n = 132) with a saline placebo (n = 116) administered from before 12 hours of age in preterm infants, who were ventilated for respiratory distress syndrome and had received surfactant treatment. Dexamethasone treatment was associated with an increased incidence of hypertension, hyperglycaemia, and gastrointestinal haemorrhage and no reduction in either the incidence or severity of chronic lung disease or mortality. A total of 195 infants survived to discharge and five died later. Follow up data were obtained on 159 of 190 survivors at a mean (SD) age of 53 (18) months. RESULTS: No differences were found between the groups in terms of perinatal or neonatal course, antenatal steroid administration, severity of initial disease, or major neonatal morbidity. Dexamethasone treated children had a significantly higher incidence of cerebral palsy than those receiving placebo (39/80 (49%) v. 12/79 (15%) respectively; odds ratio (OR) 4.62, 95% confidence interval (95% CI) 2.38 to 8.98). The most common form of cerebral palsy was spastic diplegia (incidence 22/80 (28%) v. 5/79 (6%) in dexamethasone and placebo treated infants respectively; OR 4.45, 95% CI 1.95 to 10.15). Developmental delay was significantly more common in the dexamethasone treated group (44/80 (55%)) than in the placebo treated group (23/79 (29%); OR 2. 87, 95% CI 1.53 to 5.38). Dexamethasone treated infants had more periventricular leucomalacia and less intraventricular haemorrhage in the neonatal period than those in the placebo group, although these differences were not statistically significant. Eleven children with cerebral palsy had normal ultrasound scans in the neonatal period; all 11 had received dexamethasone. Logistic regression analysis showed both periventricular leucomalacia and drug assignment to dexamethasone to be highly significant predictors of abnormal neurological outcome. CONCLUSIONS: A three day course of dexamethasone administered shortly after birth in preterm infants with respiratory distress syndrome is associated with a significantly increased incidence of cerebral palsy and developmental delay.

Anti-Inflammatory Agents↗
PubMed2000

Maternal obesity and pregnancy outcome.

BACKGROUND: Obesity, a common condition in developed countries, is recognized as a threat to health. OBJECTIVES: To describe the distribution of weight in pregnant women and evaluate the influence of obesity on pregnancy outcome in a high parity northern Israeli population. METHODS: The study included 887 women who gave birth in the Western Galilee Medical Center during the period August to November 1995. The patients were classified as underweight, normal weight, overweight, or obese according to body mass index. Maternal demographic, obstetric, and perinatal variables were compared. A control group of 167 normal weight women were matched with the obese group for maternal age, parity, and gestational age. RESULTS: Obese mothers had a higher incidence of gestational diabetes and pregnancy-induced hypertension compared to normal weight mothers (5.4% vs. 1.8%, and 7.2% vs. 0.6% respectively, P < 0.01), a higher rate of labor induction (20.4% vs. 10.2%, P < 0.01), and a higher cesarean section rate (19.6% vs. 10.8%, P < 0.05). There was also a significant difference in the prevalence of macrosomia in the offspring (16.8% vs. 8.4%, P < 0.05). CONCLUSION: Obese pregnant women are at high risk for complications during delivery and therefore need careful pre-conception and prenatal counseling, as well as perinatal management.

Adult↗
PubMed2000

Stability of common analytes in urine refrigerated for 24 h before automated analysis by test strips.

BACKGROUND: Central outpatient laboratories might find processing large numbers of urinary samples that arrive in the late afternoon inconvenient and refrigerate them overnight before testing. Furthermore, in certain settings clinics might have difficulty assuring that the urine arrives at the laboratory during the same day as the collection. Because the stability of urine samples for delayed automated dipstick analysis (Supertron) is unknown, after defining precision, we retested urines refrigerated for 24 h to determine stability. METHODS: Urinalysis was done twice on the same day and repeated after the sample was refrigerated for 24 h. Combur-10S (Roche Diagnostics) dipsticks were read automatically by a Supertron analyzer. Repeat tests on the same day were compared with tests after storage. RESULTS: Leukocyte esterase had high precision, but after storage approximately 25% of the positive samples were less reactive (P: <0.005). Precision of hemoglobin retests was also high but declined significantly after storage for 24 h. Urine protein values increased after storage. The precision and stability were excellent for nitrites, glucose, and ketones. CONCLUSIONS: The stability of the automated dipstick urinalysis varies with the substance tested. After refrigeration for 24 h, there is a risk of false-positive results for protein, false-negative results for leukocytes and erythrocytes, and little effect on glucose, nitrite, and ketone values.

Autoanalysis↗