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Biomedical subjects

A Blumenfeld

Publications and source records attributed to A Blumenfeld.

64 records · Page 4Linked to original sources
PubMed1971

Abscisic Acid and cytokinin contents of leaves in relation to salinity and relative humidity.

The question is raised whether the hormonal modifications in a plant exposed to osmotic root stress result directly from the decrease in water potential of the root environment or from disturbances of the plant's water balance.Tobacco plants were held for 24 hours under either high or low relative humidities, with or without salt. The amount of abscisic acid in the leaves of salinized plants rose markedly in low, but not in high, relative humidity. No change in the amount of extractable cytokinins was detected in any treatment. It is tentatively suggested that variations in the water content of leaves constitute a primary signal for modification of plant hormonal balance.

Journal Article↗
PubMed1970

Cytokinin Activity in Avocado Seeds during Fruit Development.

The soybean callus bioassay was used to determine levels of cytokinin activity in avocado (Persea americana) seeds.In the embryo, levels are high during the early stages of development, but diminish as the fruit grows. The level of cytokinin activity in the endosperm is very high throughout the period that this tissue exists. The seed coats have very high activity levels while the fruit is young, reaching values comparable with those found in the endosperm. The activity level falls as the rate of fruit growth slows down and disappears completely by the time the seed coats shrivel at approximately the same time the fruit reaches "horticultural maturity".

Journal Article↗
PubMed1970

Cytokinin and inhibitor activities in the avocado fruit mesocarp.

No cytokinin activity was found in methanolic mesocarp extracts after purification with petroleum ether and ethyl acetate. Cytokinin activity did appear, however, in aqueous fraction after acid hydrolysis or passage through Dowex 50 (H(+)) ion exchange columns. The level of this activity, the fruit growth rate, and the cell division rate were found to be positively correlated (with each other).An inhibitor to cytokinin activity in soybean callus bioassay was found in the petroleum ether fraction; this inhibitor is not abscisic acid. The activity of the inhibitor could be considerably reduced by raising the level of kinetin in the nutrient medium. The intensity of inhibition was found to be positively correlated with reduction in the rate of mesocarp growth.The reduction in fruit growth rate may be considered to be due to the diminution of bound cytokinin activity and (or) increased activity of an endogenous inhibitor.

Journal Article↗
PubMedDate not supplied

In vitro and in vivo effects of photodynamic therapy on murine malignant melanoma.

BACKGROUND: The role of photodynamic therapy (PDT) in the treatment of malignant melanoma is not well defined, nor is it known whether the dark melanoma cells absorb the light used in PDT. METHODS IN VITRO STUDIES: 2 x 10(5) B16 murine melanoma cells were incubated with aluminum phthalocyanine (AlpcS4, 2.5 mg/kg) and were then subjected to photoradiation (50, 100 or 200 J/cm2). Viability was then assessed. In vivo studies: HISTOLOGY: C57/B1 mice received 2 x 10(5) B16 cells subcutaneously and were randomized into study (PDT) and three control groups. AlpcS4 2.5 mg/kg was injected intraperitoneally and the mice were exposed to light (100 J/cm2). After 24 hours they were sacrificed and underwent autopsies. Survival: 40 mice were randomized into PDT (40 J/cm2) and control groups and were monitored for 50 days. Tumor growth: 40 mice were randomized into one control and three treatment groups (PDT on day 3, 6, or 12 after injection with B16 cells), and were monitored for 50 days. Temperature: Tumor temperatures before and at the end of PDT were recorded. RESULTS IN VITRO STUDIES: PDT caused a decrease in cell viability to 15.5 +/- 0.7%, 11.5 +/- 2.1%, and 1.5 +/- 0.7% (at 50, 100, and 200 J/cm2, respectively; P < .001). A significant reduction in thymidine incorporation was noted at all energy levels. In vivo studies: HISTOLOGY: PDT caused massive tumor necrosis. Survival: PDT prolonged the survival of mice (41 +/- 13.4 days) compared to controls (15.8 +/- 3.8 days, P < .001). Tumor growth: 31 days after injection with B16 cells, the tumor size was 2.6 +/- 0.3 cm in the control group and 1.6 +/- 0.2, 0.9 +/- 0.3, and 1.0 +/- 0.4 cm in the PDT groups (days 3, 6 and 12, respectively; P < .01). Temperature: PDT increased skin temperature to 42.8 degrees C +/- 1.3 degrees C, 45.3 degrees C +/- 3.5 degrees C, and 51.7 degrees C +/- 2.7 degrees C at 40, 60, and 100 J/cm2, respectively (P < .01). CONCLUSIONS: Photodynamic therapy was found to have significant effects in experimental melanoma in mice. The role of PDT in human melanoma remains to be studied.

Animals↗
PubMedDate not supplied

Prenatal diagnosis of oculocutaneous albinism type I: review and personal experience.

Oculocutaneous albinism type I (OCA I) comprises autosomal recessive syndromes of hypopigmentation and low vision, caused by the lack of tyrosinase activity. Affected families seek genetic counseling and prenatal diagnosis as preventive measures. Until recently, prenatal diagnosis of OCA I was achieved by histologic and electron microscopic examination of fetal skin biopsies. Lately, a molecular genetic approach has become possible by the identification of the two mutated copies of the TYR gene, coding the tyrosinase, in which over 60 mutations have been identified. We report here our experience in prenatal diagnosis of OCA I using the two strategies. Thirty-four prenatal tests were performed in fetuses at risk for OCA I. In 31 cases the diagnosis was made in fetal scalp biopsies using the histological approach. The microscopic observations revealed normal melanogenesis in 26 biopsies. Five albino fetuses were diagnosed by the demonstration of arrest of melanogenesis in early stages I and II. In three pregnancies, molecular genetic tests were performed on DNA extracted from amniocytes, using direct mutation analysis (in one), and complemented by linkage analysis (in two). One albino and two normally pigmented fetuses were diagnosed. The prenatal molecular genetic test can be applied to families when at least one mutation is diagnosed in the albino patient. The histological approach is applicable in all families at risk for OCA I.

Albinism, Oculocutaneous↗
PubMedDate not supplied

Cognitive screening of psychiatric patients.

The goal of the present study was to explore characteristic cognitive profiles which distinguish between psychiatric patients with and without organic mental disorder (OMD), using Neurobehavioral Cognitive Status Examination (NCSE), a brief screening battery. A mild degree of cognitive deficits was found to be common in the Non-OMD psychiatric group. The deficit was especially pronounced in the Memory domain. Patients in the OMD group demonstrated a higher frequency of moderate and severe impairment. The best discriminator was the scale assessing visuospatial constructional ability and visual memory. Verbal memory deficit in OMD patients was more severe than in Non-OMD patients. Implications for improving diagnostic sensitivity of cognitive screening are discussed.

Adolescent↗
PubMedDate not supplied

Aspects of validity and reliability of the Neurobehavioral Cognitive Status Examination (NCSE) in assessment of psychiatric patients.

The validity and reliability of the NCSE were assessed on a sample of 192 psychiatric patients from a county general hospital with a mean age of 33.5 years and mean education of 12 years. The analyses revealed that demographic and general health factors need to be taken into consideration in interpreting the NCSE results. Predictive accuracy of the screening items for subsequent performance on metric items across different scales ranged from good to poor. A comparison of success versus failure on the screen for Construction scale with scores on metric items for this scale revealed a high number of false negative errors made using the screening item. Administration of both screen and metric items on this scale for all patients was recommended. Indices of internal consistency of the Orientation scale were adequate. A factor analysis on the scale scores extracted two factors. The second factor identified a subset of scales which assess the patients' functional capacity in dealing with the demands of everyday environment. Test-retest reliability of the NCSE assessed on a subsample of 28 subjects, was high for 7 scales, whereas low stability was demonstrated by Construction, Memory and Calculation scales (r = .79, .52 and .81, respectively). Practice effect and fluctuating attention might contribute to the low stability of these scales. These modifications in the test administration procedure would improve the accuracy of assessment of cognitive deficits in psychiatric patients.

Adolescent↗
PubMedDate not supplied

The BsmI vitamin D receptor gene polymorphism in Israeli populations and in perimenopausal and osteoporotic Ashkenazi women.

BACKGROUND: The association between vitamin D receptor (VDR) gene polymorphisms and bone mineral density (BMD) is controversial, and may be effected by ethnic ancestry and age. AIMS: To determine the distribution of the BsmI VDR gene polymorphism in healthy Israeli populations, and to study its association with BMD in perimenopausal and osteoporotic Ashkenazi women. METHODS: Allele and genotype frequencies of the VDR gene defined by BsmI restriction site were determined in 634 healthy Israelis of seven ethnic groups, 90 Ashkenazi perimenopausal women and in 75 Ashkenazi osteoporotic women. Genotype-related differences in spinal and femoral neck BMD were determined in Ashkenazi perimenopausal women. Allele and genotype frequencies in Ashkenazi osteoporotic women were compared with Ashkenazi controls. RESULTS: The frequency of the BB genotype was higher in Yemenites compared with Ashkenazi and Libyan Jews (23, 11 and 8%, respectively, p < 0.05), and lower in Ashkenazi compared with Iraqi and Persian Jews (11, 20 and 21%, respectively, p = 0.05). BMD did not vary by genotype in perimenopausal women, nor were there differences in the frequencies of the B allele or the BB genotype in osteoporotic women compared with controls. CONCLUSIONS: There is ethnic variability in the frequency of the BsmI VDR gene polymorphism. In Ashkenazi perimenopausal and osteoporotic women this polymorphism is not associated with BMD.

Adolescent↗