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Biomedical subjects

Y Tal

Publications and source records attributed to Y Tal.

At least 19 recordsLinked to original sources
PubMed2001

Modulation of proteinase-K resistant prion protein by prion peptide immunization.

Prion diseases are caused by conformational alterations in the prion protein (PrP). The immune system has been assumed to be non-responsive to the self-prion protein, therefore, PrP autoimmunity has not been investigated. Here, we immunized various strains of mice with PrP peptides, some selected to fit the MHC class II-peptide binding motif. We found that specific PrP peptides elicited strong immune responses in NOD, C57BL/6 and A/J mice. To test the functional effect of this immunization, we examined the expression of proteinase-K-resistant PrP by a scrapie-infected tumor transplanted to immunized syngeneic A/J mice. PrP peptide vaccination did not affect the growth of the infected tumor transplant, but significantly reduced the level of protease-resistant PrP. Our results demonstrate that self-PrP peptides are immunogenic in mice and suggest that this immune response might affect PrP-scrapie levels in certain conditions.

Amino Acid Sequence↗
PubMed2001

Enumeration and factors influencing the relative abundance of a denitrifier, Pseudomonas sp. JR12, entrapped in alginate beads.

The relative abundance of the denitrifier, Pseudomonas sp. JR12, was examined in an alginate-based entrapment complex under non-sterile, denitrifying conditions. Immuno-labeling of the Pseudomonas inoculant followed by flow cytometry (FCM) was used for determination of the relative abundance of this bacterium under the various incubation conditions. Additional information on the relative abundance of the inoculant was obtained by a quantitative enzyme-linked immunosorbent assay (ELISA) and results obtained by FCM and ELISA were compared. Ambient nitrate levels controlled the successful, long-term proliferation of the inoculant. At low ambient nitrate levels, Pseudomonas sp. remained the dominant microorganism during incubation. Higher ambient nitrate concentrations, attained by either decreasing the inoculum size of Pseudomonas sp. or raising inlet nitrate concentrations of the medium supplied to the incubation vessels, resulted in a gradual shift toward other, nitrite-accumulating denitrifiers. Thus far, most studies on the use of entrapped microorganisms for bioremediation purposes have been conducted under controlled laboratory conditions. Based on this study, conducted under non-sterile laboratory conditions, it is concluded that in-situ bioremediation using entrapped target microorganisms is bound to fail without a proper understanding of the factors that cause the target microorganism to out-compete undesired microbial invaders. Furthermore, based on the close agreement between the two detection methods used, it is concluded that flow cytometry provides a rapid and accurate tool for the detection of the relative abundance of immuno-labeled target organisms in heterogeneous microbial populations.

Environmental Monitoring↗
PubMed2000

Infants with a thumb-in-fist posture.

OBJECTIVE: In early infancy the infant's thumb is not infrequently enclosed within the palm, ie, thumb-in-fist (TIF). This posture has received scant attention in the neurodevelopmental literature. Its prevalence, resolution, and clinical associations were investigated in this study. METHODOLOGY: Two hundred sequentially born, apparently healthy full-term newborn infants comprised the cohort. The whole study group was followed up until the disappearance of the TIF occurred. In the first 150 of the cohort, additional data on development and the neurological status were obtained at 12 months of life. RESULTS: In 125 infants (62.5%) of the total cohort, a TIF was noted. The mean age of disappearance was 1.5 months, and no TIF persisted after 7 months old. No relationship was noted between the TIF resolution and abnormal neurological signs or gross or fine motor development. The only association noted between age of resolution of the TIF and the neurodevelopmental status was a delay in language attainment at the 12-month screening. CONCLUSIONS: The TIF posture in infancy was noted in 65% of our cohort, and it had resolved in all infants by 7 months old. Therefore, a TIF posture after this age should alert the clinician to the possibility of possible neurological dysfunction. An unanticipated association of a delay in the 12-month language milestone attainment was noted in those infants with later resolution of the TIF posture. No data on language development in this group were obtained after 12 months old; therefore, the clinical significance of this finding is not yet elucidated.

Cohort Studies↗
PubMed1998

[Nasopharyngeal colonization with Streptococcus pneumoniae in pediatric respiratory infections].

During the winter of 1995, nasopharyngeal colonization of Streptococcus pneumoniae was evaluated in 204 children with respiratory infection and 107 normal control children. There was no difference in gender or mean age between the groups, and no difference in carrier rate between sick (24.5%) and normal (22%) children (p = 0.6). Carrier rates were 19%, 32%, 31% and 17% at 6, 12, 24 and 48 months, respectively. Penicillin-resistant pneumococci (PRP) were found in 42% of sick and 16.6% of normal children, (p < 0.05). Resistance to more than 2 antibiotics was found in 28% of sick and in 12.5% of normal children. PRP were found in 67% and 34% of sick children with and without prior antibiotic treatment (p < 0.05). We conclude that there is no difference in the carrier rate of Streptococcus pneumoniae between sick and normal children. However, the high prevalence of PRP in children with respiratory infections is probably due to prior antibiotic treatment.

Carrier State↗
PubMed1998

Apnoea-associated heart rate changes among preterm and full-term infants exposed to hyperthermia.

Heart rate (HR) changes associated with apnoea (> 3 s) were analysed in 10 preterm infants (30.6 +/- 1.5 weeks) at post-conceptional age of 40 +/- 1.5 weeks and 10 full-term (FT) infants (39 +/- 1 weeks) before, during and after exposure to increased environmental temperature (5 degrees C above normothermia). A significantly increased HR was found in the study group during the baseline (normothermia), heating, cooling and final normothermic phase compared with the control infants. No significant difference was found between the groups during the hyperthermic stage. A significant relative increase in HR was found among the preterm infants but not among FT infants during central apnoea at the hyperthermia phase. Our results indicate that HR control during apnoea in preterm infants is more labile then among FT infants while being exposed to increased environmental temperature.

Apnea↗
PubMed1998

Fetal cardiac measurements derived by transvaginal and transabdominal cross-sectional echocardiography from 14 weeks of gestation to term.

OBJECTIVE: Most of the routine ultrasound screening in our institution consists of early transvaginal examinations at 14-17 weeks. Complete fetal echocardiography is performed in every case. However, normal values for most fetal cardiac structures at this stage of gestation are not available. Our aim was to construct normal ranges for fetal cardiac structures, derived from cross-sectional echocardiography, at 14-40 weeks of gestation. DESIGN: A prospective study was performed. The study group consisted of 637 pregnant women referred for a routine sonographic examination. Women with abnormal prenatal or postnatal outcome were not included in the study. Transvaginal examinations were used for 14-17 weeks of gestation. More advanced pregnancies were examined transabdominally. RESULTS: We constructed normal ranges for the left and right end-diastolic transverse ventricular diameters (n = 637), left/right ventricular ratio (n = 637), aortic root diameter (n = 637), pulmonary artery diameter (n = 637), aortic/pulmonary ratio (n = 490), left and right transverse atrial diameters (n = 201) and left/right atrial ratio (n = 201). CONCLUSIONS: The results provide the examiner with normal ranges for fetal cardiac structures for the early transvaginal examination. The continuity of all curves from 14 to 40 weeks of gestation allows follow-up of any specific fetus to term.

Aorta↗
PubMed1998

Platelet activation in patients with antiphospholipid syndrome.

The binding of antiphospholipid antibodies to circulating platelets and the potential association with thrombocytopenia and platelet activation was investigated in 25 patients with primary antiphospholipid syndrome (APS). Fourteen patients had a platelet count above 150 x 10(9)/l, and 11 patients had mild to moderate thrombocytopenia of 50-150 x 10(9)/l. The presence of platelet autoantibodies was investigated by immunofluorescent binding. No correlation between the presence of autoantibodies on platelets and thrombocytopenia was found. The binding of antibodies in patients' serum and platelet eluates was investigated by performing enzyme-linked immunosorbent assays with phospholipids as antigens. In seven patients antibodies to negatively charged phospholipids were present in platelet eluates. Platelet activation was measured by flow cytometry using a fluorescein isothiocyanate (FITC) labeled monoclonal antibody to P-selectin (CD62). The binding of anti-P-selectin to patients' platelet surface P-selectin was not increased, compared with the binding to platelets obtained from normal donors. Platelet serotonin concentration in APS patients was significantly lower than that found in the platelets of normal controls. More studies are necessary to determine the exact role of antiphospholipid antibodies in the pathogenesis of thrombocytopenia, and to elucidate the cause of low serotonin levels in platelets of APS patients.

Adolescent↗
PubMed1998

Light-Mediated Nitrite Accumulation during Denitrification by Pseudomonas sp. Strain JR12.

The effect of light on the denitrifying characteristics of a nonphotosynthetic denitrifier, Pseudomonas sp. strain JR12, was examined. Already at low light intensities, nitrite accumulated as a result of light inhibition of nitrite but not of nitrate reduction rates. Exposure of this bacterium to light caused a photooxidation of cytochrome c, an intermediate electron carrier in its respiratory pathway. Photoinhibition of nitrite reduction was reversible, as nitrite reduction rates returned to preillumination levels when light-exposed cells were returned to dark conditions. Antimycin A reversed the inhibitory effect of light on nitrite reduction by preventing a reversed electron flow. Aerobic respiration by this bacterium was not affected by light.

Journal Article↗
PubMed1997

The clinical significance of rigors in febrile children.

UNLABELLED: The objective of the study was to evaluate the significance of rigor as a predictor of bacterial infection in hospitalized febrile infants and children. One hundred febrile children with rigor were studied and compared to 334 febrile matched controls without rigor. All underwent clinical evaluation and appropriate laboratory investigations. The patients were then divided into "bacterial" and "non bacterial" infection groups, as defined in the text. It was demonstrated that 66% of the patients with rigor belonged to the bacterial infection group versus 50% in the non-rigor group (P < 0.005). There was a significantly greater yield of positive blood cultures in the patients with rigor (P < 0.04), especially those over the age of 1 year (P < 0.015). The only laboratory examination of potential value as a predictor of bacterial infection in children with rigor was the band count. An absolute band count of more than 1500/mm was significantly more frequent in the rigor group (P < 0.003), and the combination of a rigor and band count of more than 1500 increased the relative risk for a bacterial infection by a factor of 1.35. These data demonstrate that rigor in hospitalized febrile infants or children significantly increase the likelihood of bacterial infection. CONCLUSION: Although the absence of rigors in febrile children does not exclude bacterial aetiology, their presence significantly increase the probability of an infection requiring appropriate workup and a reader institution of antibiotic therapy.

Adolescent↗
PubMed1996

The parachute reactions in normal and late walkers.

To study the relationship of the parachute responses to the age of independent walking, three groups of infants were prospectively examined: a normal sitting, normal walking group; a late sitting, normal walking group; and a late sitting, late walking group. All other spheres of the neurodevelopmental examination were normal. It was found that when the parachute responses appeared by age 10 months in the late sitting infants, most of them would achieve independent walking by 15 months. A delay in the parachute reaction in these infants predicted a delay in walking.

Child Development↗
PubMed1996

Influence of Volatile Fatty Acids on Nitrite Accumulation by a Pseudomonas stutzeri Strain Isolated from a Denitrifying Fluidized Bed Reactor.

Intermediate nitrite accumulation during denitrification by Pseudomonas stutzeri isolated from a denitrifying fluidized bed reactor was examined in the presence of different volatile fatty acids. Nitrite accumulated when acetate or propionate served as the carbon and electron source but did not accumulate in the presence of butyrate, valerate, or caproate. Nitrite accumulation in the presence of acetate was caused by differences in the rates of nitrate and nitrite reduction and, in addition, by competition between nitrate and nitrite reduction pathways for electrons. Incubation of the cells with butyrate resulted in a slower nitrate reduction rate and a faster nitrite reduction rate than incubation with acetate. Whereas nitrate inhibited the nitrite reduction rate in the presence of acetate, no such inhibition was found in butyrate-supplemented cells. Cytochromes b and c were found to mediate electron transport during nitrate reduction by the cells. Cytochrome c was reduced via a different pathway when nitrite-reducing cells were incubated with acetate than when they were incubated with butyrate. Furthermore, addition of antimycin A to nitrite-reducing cells resulted in partial inhibition of electron transport to cytochrome c in acetate-supplemented cells but not in butyrate-supplemented cells. On the basis of these findings, we propose that differences in intermediate nitrite accumulation are caused by differences in electron flow to nitrate and nitrite reductases during oxidation of either acetate or butyrate.

Journal Article↗
PubMed1996

Reversible brain atrophy and reversible developmental retardation in a malnourished infant.

An 11-month-old infant suffering from microcephalus, developmental delay, severe failure to thrive and marked cortical atrophy on brain CT is presented. The cause of this condition was total calorie malnutrition induced by the emotional dysfunction of the mother. Improvement of the maternal-infant relationship, combined with appropriate nutrition, transformed the infant within 2 months into a normally developing baby with body weight and head circumference within the normal percentile range. A corresponding improvement was found in the brain CT.

Cerebral Cortex↗
PubMed1995

Transverse bond strength of repaired acrylic resin strips and temperature rise of dentures relined with VLC reline resin.

This study measured the transverse strength of polymethyl methacrylate heat-cured resin samples repaired with Triad visible light-cured reline resin with and without bonding pretreatments and with autopolymerizing resin, and it measured the temperature rise of Triad resin during relining of complete dentures at various curing cycles. The results indicated that pretreatment with either monomer or Triad bonding agent improved the bond of the Triad visible light-cured reline resin to the heat-cured resin. However, the use of the monomer rather than bonding agent resulted in a stronger bond and obtained values similar to those of samples repaired with autopolymerizing resin. Polymerization of samples repaired with Triad resin in the curing unit for two cycles of 5 minutes with 1 minute between cycles resulted in bubble formation and severe distortion of the heat-cured resin in the samples. Curing of the relined dentures for 10 minutes as recommended by the manufacturer raised the average peak temperature to 120 degrees C. In addition, it was shown that interrupting the light curing cycle attenuated the temperature rise, but it also resulted in a relatively softer reline resin. A continuous light curing of at least 5 minutes with the adjunct temperature rise is required to reach 1-hour hardness of 21.8 Vickers hardness number of the Triad reline resin.

Acrylic Resins↗
PubMed1995

Congenital toxoplasmosis: a significant cause of neurological morbidity in Israel?

The incidence of congenital toxoplasmosis in Israel is largely unknown, as is the impact of this condition on the neurological diseases of childhood. We examined the association between toxoplasmosis and three neurological disorders: epilepsy, cerebral palsy, and nerve deafness. Ninety-five children 1-15 years of age who had one of these three diagnoses but who had not had perinatal meningitis or anoxia and had no genetic predisposition for the documented neurological disorder were eligible for the study; 109 children hospitalized for elective surgery served as age-matched controls. Demographic and serological data were analyzed by logistic regression. The prevalences of serum antibodies to Toxoplasma gondii in the study and control groups were 22% and 9%, respectively. Children with one of the three neurological disorders were significantly more likely to have IgG antibodies to T. gondii (relative risk, 2.5; P = .03). The relative risk of seropositivity was remarkably high (7.1) among children with nerve deafness (P = .01). Large-scale prospective cohort studies of pregnant women are needed to substantiate the impact of congenital toxoplasmosis on the neurological diseases of childhood in Israel.

Adolescent↗
PubMed1995

CPAP treatment of obstructive sleep apnoea and neurodevelopmental deficits.

Four boys aged 6-16 years with neurodevelopmental deficits were treated with CPAP for obstructive sleep apnoea. Their diagnoses were: Obesity with mild mental retardation, (2) attention deficit hyperactivity disorder, (3) epilepsy associated with left hemiparesis and (4) mild mental retardation due to fragile X syndrome. Previous therapeutic attempts, including adenotonsillectomy, amitriptyline and methylphenidate in our patients prior to CPAP treatment were unsuccessful. A follow-up period of 12-48 months demonstrated a number of clinical benefits such as improvement in sleep quality and daily arousal, and a decrease in the frequency of seizures and episodes of pneumonia. Polysomnographic studies indicated a significant improvement in sleep parameters such as apnoea frequency, awakenings, sleep efficiency and arterial oxygen saturation. Side effects were mild and readily alleviated. CPAP is a feasible therapeutic intervention in intractable obstructive sleep apnoea of childhood, even when associated with neurodevelopmental deficits.

Adolescent↗
PubMed1994

Relationship between the parachute reactions and standing and walking in normal infants.

Assumption of the vertical position and independent walking are potentially hazardous motor milestones in the developing infant. It has been presumed that the parachute reactions evolved to protect infants from injury during this developmental stage. To determine the relationship between the appearance of the upper and lower parachute reactions and the developmental milestones of unsupported standing and independent walking, 190 normal infants were prospectively studied. The upper parachute reaction was found to precede the lower by less than a month (mean age of appearance: 8.9 and 9.2 months, respectively). More than one-half of the cohort achieved standing without either the upper (49%) or lower parachute reaction (57%); however, no independent walking occurred without the upper parachute reaction, and only 2 of 190 infants (1%) walked independently without the lower parachute reaction. Onset of walking occurred about 4 months after the appearance of the upper parachute reaction. The significance of these findings is discussed.

Accidental Falls↗