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Biomedical subjects

O Tal

Publications and source records attributed to O Tal.

12 recordsLinked to original sources
PubMed2006

Electronic properties of doped molecular thin films measured by Kelvin probe force microscopy.

We report on high-resolution electronic measurements of doped organic thin-film transistors using Kelvin probe force microscopy. Measurements conducted on field effect transistors made of N,NI-diphenyl-N,NI-bis(1-naphthyl)-1,1I-biphenyl-4,4I-diamine p-doped with tetrafluoro-tetracyanoquinodimethane have allowed us to determine the rich structure of the doping-induced density of states. In addition, the doping process changes only slightly the Fermi energy position with respect to the highest occupied molecular orbital level center. The moderate change is explained by two counter-acting effects on the Fermi energy position: the doping-induced additional charge and the broadening of the density of states.

Journal Article↗
PubMed2005

Direct determination of the hole density of states in undoped and doped amorphous organic films with high lateral resolution.

We investigate the density of states (DOS) for hole transport in undoped and doped amorphous organic films using high lateral resolution Kelvin probe force microscopy. Measurements are done on field effect transistors made of N,N1-diphenyl-N, N1-bis(1-naphthyl)-1,10-biphenyl-4,4II-diamine undoped or p doped with tetrafluoro-tetracyanoquinodimethane. We determine the DOS structure of the undoped material, including an anomalous peak related to interfaces between regions of different surface potential, the DOS doping-induced broadening, and doping-induced sharp peaks on the main DOS distribution.

Journal Article↗
PubMed2005

Epidermolytic hyperkeratosis type PS-1 caused by aberrant splicing of KRT1.

Mutations in the keratin 1 (KRT1) gene underlie epidermolytic hyperkeratosis (EHK). This autosomal dominant disorder is characterized by phenotypic heterogeneity. In the present study, we assessed a 33-year-old individual presenting with severe palmoplantar keratoderma and histopathological findings suggestive of EHK. We analysed genomic DNA extracted from the patient's blood lymphocytes for pathogenic mutations in KRT1. A heterozygous 4-bp deletion was identified in intron 1 of the gene (591+3_+6delGAGT), suggesting the possibility that it may interfere with the normal splicing of intron 1. We detected a 66-bp deletion in KRT1 mRNA extracted from the patient's skin, predicted to result in the translation of a mutant KRT1 lacking 22 amino acids, including the conserved helix initiation motif. The identification of this unusual and novel mutation underscores the diagnostic importance of sequence analysis of keratin gene noncoding regions.

Adult↗
PubMed2000

Deletion patterns of the STS gene and flanking sequences in Israeli X-linked ichthyosis patients and carriers: analysis by polymerase chain reaction and fluorescence in situ hybridization techniques.

BACKGROUND: Deletion of the entire steroid sulfatase (STS) gene is the most common molecular defect in X-linked ichthyosis (XLI) patients. Usually, additional flanking sequences are also missing. The aim of this study was to estimate the extent of deletions in an ethnically heterogeneous population of Israeli XLI patients. METHODS: Multiplex polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) techniques were applied in the analysis of blood samples of 24 patients and amniotic cells of seven affected fetuses from 22 unrelated families. RESULTS: In 19 families, a large deletion of the 2-3 megabase was found. It included the whole STS gene and spanned adjacent areas up- and downstream between the loci DXS 1139 and DXS 1132. Two unrelated families of Iraqi ancestry had a partial deletion of the gene and its centromeric adjacent sequence. In another family, the telomeric end of the extragenic segment was only partially missing. Application of FISH on metaphase blood cells and interphase amniotic cells confirmed the diagnosis of XLI in all patients, except the three with partial intragenic deletion. In those cases, the remaining fraction of the gene was sufficient to provide a false negative result. Diagnosis of carriers and prenatal diagnosis in uncultured cells was applicable only by FISH. CONCLUSIONS: Our study revealed a remarkable heterogeneity in the deletion pattern among Israeli patients with XLI. This heterogeneity could not be attributed to specific ethnic groups because of the small size of the study group. More studies involving patients of various ancestries should be carried out. In addition, this study demonstrated the usefulness of the FISH technique in the prenatal diagnosis of fetuses with suspected XLI.

Adolescent↗
PubMed2000

Use of sunscreen is linked with elevated naevi counts in Israeli school children and adolescents.

Epidemiological evidence indicates that a fair complexion and exposure to solar radiation in early years contribute to the proliferation of naevi and subsequent melanoma risk. To determine whether protection from sunlight is associated with lower naevi counts, we examined the prevalence and risk factors of naevi in a sample of Israeli school pupils. Whole body counts of naevi were recorded in 974 out of 1312 (74.2%) recruited pupils (7 and 12 year olds) from Ramat-Gan and Jerusalem. Host characteristics and habits of sun exposure were obtained using questionnaires. In each age group and geographic area, the mean whole body naevi counts, adjusted for confounders, were higher among males, pupils of European-American descent, and those susceptible to sunburn. The contributions to naevi risk of fair skin colour and frequent recreational sun exposure were higher among 7 year olds. Regular sunscreen use contributed to the naevi risk for both age strata in Ramat-Gan (at age 7, rate ratio [RR] = 1.7, 95% confidence interval [CI] = 1.3-2.2; at age 12, RR = 1.5, 95% CI = 1.1-2.1). Among the younger age group in Ramat-Gan, even seldom compared with no use of sunscreen was associated with higher naevi counts (RR= 1.5, 95% CI = 1.2-2.0). Similar patterns were noted with the pupils from Jerusalem. In conclusion, the elevated naevi count with increased sunscreen use indicates that sunscreens apparently do not modify the genetic predisposition to naevi proliferation. For better protection of children and adolescents, including those who use sunscreens, from the naevogenic effect of solar radiation, they should be encouraged to limit their exposure and wear protective clothing when in the sun.

Adolescent↗
PubMed2000

The fitness-for-work evaluation of a young patient with essential thrombocythemia.

We describe a case of a military cadet, a candidate for submarine service, who was diagnosed with essential thrombocythemia (ET). The estimated risk in the literature for major clinical complications in ET patients is about 5-20%. Our report concerns a young asymptomatic patient where the estimated risk is probably much lower. We think that the activity in the marine corps, which at times is involved with some degree of dehydration, might increase the risk for thromboembolic events. The possibility of a major thromboembolic complication occurring at sea could complicate and endanger the patient's life, especially when an evacuation to a hospital is required. A submarine officer has a responsibility to other people's life who depend on his skills and ability. In case of a major complication which can cause sudden incapacitation, the consequences can be catastrophic to many. Opposed to the considerations to disqualify the young cadet stands the fact that his training was expensive, and that it would be unfortunate to disqualify a very talented young person. We thus recommended to clear the cadet as a marine officer in teaching jobs, in sites were medical assistance is available in a short period of time. In our opinion he should be disqualified from serving in combat jobs where there is a greater risk for him and for the men under his command.

Adolescent↗
PubMed1993

[Cutaneous larva migrans].

Larva migrans is a rare cutaneous parasitic infestation, whose incidence in Israel has increased over the past few years. This is mainly due to the growing number of Israelis traveling to the Far East and to Central and South America. We present 4 such cases. The treatment of choice for this parasite is thiabendazole, an imidazole with anthelminthic properties.

Adult↗
PubMed1985

Pericoronitis: a reappraisal of its clinical and microbiologic aspects.

Pericoronitis is an infectious disease of the operculum overlying an erupting or semi-impacted tooth. It manifests itself mainly in late adolescence and young adulthood and nearly always occurs around the lower third molar. The distinctive location, age, clinical picture, and link with predisposing factors warranted a reappraisal of pericoronitis and its etiology. Spirochetes and fusobacteria proved prevalent at all stages of the disease. The presence of these microbacteria may provide a clue as to the late appearance, particular location, and singular clinical picture of pericoronitis. The fact that spirochetes and fusobacteria are also found in acute necrotizing ulcerative gingivitis, and have been associated with alveolar osteitis, indicates a possible relationship between these disorders and pericoronitis.

Adolescent↗