Lower frequency of Gaucher disease carriers among Tay-Sachs disease carriers.

The heterozygote frequency of Gaucher disease (GD) and Tay-Sachs disease (TSD) is distinctly high among Ashkenazi Jews (1:29 for TSD and 1:16 for GD). Two main theories have been suggested to explain this high occurrence: a founder effect with subsequent genetic drift, and a selective advantage of heterozygotes. We compared the frequency of the GD most common mutation (1226A-->G) among carriers of the common TSD mutation (+1277 TATC) with the frequency of this mutation in the general Ashkenazi population. The frequency of GD carriers among 308 TSD heterozygotes was 1:28 which is about half the expected (P = 0.03). These results indicate that carriers of both diseases do not possess additional evolutionary advantage over single mutation carriers. A reasonable interpretation of these findings is that one or both mutations have arisen relatively recently in different regions of Europe and have not yet reached genetic equilibrium.

Time dependency of hematopoietic growth factor coupled to chronotoxicity of carboplatin.

A growing body of data suggests that cancer therapy may be improved and toxicity reduced by administration of antineoplastic agents and cytokines at carefully selected times of the day. The time-dependent effects of each of the drugs have been documented, but not their mutual time dependencies. In the present studies we sought to determine the best time for granulocyte colony-stimulating factor (G-CSF) administration after carboplatin treatment. Carboplatin was injected in different groups of ICR mice at four different circadian stages for 5 consecutive days. Mice were synchronized with an alternation of 12 h of light (from 6:00 a.m. to 6:00 p.m.) and 12 h of darkness. After the last injection, peripheral WBCs of three mice from each group were counted every 4 h over a 24-h period. Bone marrow toxicity was estimated with the mean 24-h WBC count. The most severe leukopenia occurred in the group injected at 3:00 p.m. - 9 h after light onset. The second set of experiments evaluated the time-dependent effect of G-CSF when singly injected or given after carboplatin injections for 5 days only at 3:00 p.m. G-CSF was injected into various groups on days 8 and 9 at the same four different circadian stages. On the 10th day after the first injection, peripheral WBCs of three mice from each group were counted every 4 h over a 24-h period. Time-dependent effects were observed when G-CSF was injected as a single agent. When G-CSF was given at various times to the group with the most severe carboplatin-induced leukopenia, peripheral WBC count recovery was monitored at all injection times; it reached its highest level (exceeding even that of the control) when G-CSF was injected at 3:00 a.m. Dosing times of both chemotherapy and growth factor are relevant for optimization of carboplatin's hematologic tolerability.

Genetic control of biological rhythms: independent expression of each rhythm parameter.

Biological rhythm whose pattern approaches a sinusoidal curve can be characterized by four parameters: Period, Mesor, Acrophase and Amplitude. Inheritance patterns of these parameters were assessed by monitoring White Blood Cell (WBC) count rhythms of C57BL/6J mice, BALB/c mice and the F1 progeny prior and after injection of Cisplatinum at either 0900, 1500, 2100, or 0300. All untreated mice exhibited similar WBC rhythms while a variety of rhythm phenotypes was revealed among the injected mice. Analyses of the variety in the parental strains and F1 progeny suggested that each of the rhythm parameters is independently controlled.

Strain dependent response of circadian rhythms during exposure to continuous illumination.

Enzymes activities were measured, at three hours intervals, during 30 hours, in various tissues of C57BL/6J and A/J male mice. The measurements, were carried out on mice which were exposed for two, five and twenty one days to continuous illumination. Identical measurements were performed also on mice which were kept in alternating 14 hours light: 10 hours dark. Activity patterns of each group were analysed to test the presence, or absence, of rhythm characteristics. The results of the experiments with C57BL/6J have been previously reported. The comparison of the results, which were obtained from the two strains revealed that under exposure to alternating light: dark conditions all activity patterns exhibited a significant circadian rhythm. Except for one enzyme (thymus GAPD), the times of peak activity (acrophase) were identical for all other examined enzymes, in both strains. On the other hand when the two strains were exposed to continuous illumination they differed in their response to the effect of continuous light. The activity of the same enzyme exhibited different periodicity and/or different acrophase in each of the two strains. This variability reflects the existence of genetic differences, between the strains in the free running behavior of these enzymes' activity rhythms.

Gender-dependent differences in biological rhythms of mice.

The advantage of a variable's rhythm resides in its optimal time-phasing. This implies that, for a given function, members of a species will strive to exhibit identical time-phasing namely, their inter-individual genetic differences will be masked. To examine the generality of this assumption we explored if inbred mice exhibit gender dependent differences in rhythm parameters of biochemical variables. Male and female mice, entrained by exposure to 12:12 light:dark illumination were sacrificed, every 3 hours over a 27 hours period. Activities of creatine-phosphokinase (CK) and alkaline- phosphatase (AP), white blood cell (WBC) counts and urea nitrogen (UN) concentration were determined at each time point. For each significant rhythm four parameters were computed: period, acrophase, mesor and amplitude. In addition two derived parameters were also calculated: relative-amplitude (RA) and the rate of change in RA (CRA) which provide information about the slope and width of the peak. Patterns of most variables exhibited a compound rhythm containing two significant periodicities. Gender dependent differences were documented in the parameters of most rhythms indicating that the genetic and physiological differences limit to a certain extent the phasing ability of the entraining signals and point to an independent control of each of the rhythm parameters.

Differences in rhythms of enzymatic activity of maternal and fetal blood.

Blood specimens were obtained at different daily times from the umbilical cord and brachial vein from 53 women within 10 minutes after delivery. Enzyme activities were measured in the white blood cells (WBCs) and serum of each sample. For each enzyme, the results were grouped according to sampling (delivery) times and arrayed to form a 24h time series. Separate time series were generated for maternal and fetal enzymes. Analysis of variance (ANOVA) and cosine best-fit analyses were applied to elucidate significant differences between enzyme activity patterns of mothers and fetuses with regard to time dependency, number of peaks, and acrophases. These and previously documented results indicate that not all mothers and fetuses have rhythms that are concordant. For some enzymes of fetuses, the activity rhythms differ in phase and shape of the time series pattern from those of the mothers; for other enzymes, the activity rhythms develop after birth.

Circadian rhythms of enzymes' activity in mice tissues during exposure to continuous illumination.

Activity rhythms of enzymes were determined in various tissues of C57BL/6J male mice. The determinations were carried out on mice which were kept in 14 hr light: 10 hr dark regimen, and on day 2, day 5 and day 21 during exposure to continuous illumination. Locomotor activity rhythms were followed in light: dark and up to the seventh day in constant light. All the activities exhibited a significant circadian rhythm in the light: dark regimen. During the exposure to continuous illumination, the locomotor activity exhibit a free running circadian rhythm with a consistent 24 hr and 40 min, major period component. At the same time recording the rhythms of enzyme activity; enzymes exhibited various formats of response which differed from those of the locomotor activity. The results suggest that rhythms of enzyme activity, as well as the desynchronization of the rhythms, are not enzyme specific.

[Comprehensive geriatric assessment--its clinical, social and economic importance and prospects].

It is well known that many elderly patients are referred to nursing homes because of "functional decline" without being thoroughly investigated. We studied 9 elderly patients, all referred to hospital due to functional decline and diagnosed as follows: spinal stenosis--2 cases, depression--3, thyrotoxicosis--1, Parkinson--1, polypharmacy and congestive heart failure--1 patient each. Proper diagnosis and appropriate treatment prevent unnecessary hospitalization in nursing homes. Our study is meant to draw attention to this crucial aspect of geriatric medicine.

Novel mutations in two families with Darier's disease.

BACKGROUND: Darier's disease (DD) is an autosomal dominant skin disorder characterized by abnormal keratinization and acantholysis. Deleterious mutations in the gene ATP2A2 which encodes SERCA2, a calcium pump of the sarco/endoplasmic reticulum underlie the disease. OBJECTIVE: To identify the genetic defect in two Jewish families of eastern-European ancestry with DD. METHODS: DNA was extracted from peripheral blood of six patients and three healthy members of the two families. Polymerase chain reaction (PCR) was carried out to amplify the exons and flanking intron boundaries of the ATP2A2 gene followed by direct sequencing. Restriction fragment analysis verified the presence or absence of the mutations. Results Two novel mutations were identified. A nonsense mutation, a change of C391 to T (R131X) in exon 5, was found in one family and a missense mutation, a change of A530 to C (Q177P) in the second. The mutations were not present in 50 healthy individuals of the same ethnic origin. Both pathogenic mutations are in codons that are located in a highly conserved cytoplasmic beta-strand domain which functions as the transduction site. CONCLUSION: The existence of two mutations in two Jewish families of the same ancestry might confirm the previously published reports that most mutations in that gene are private.

Detection of Tay-Sachs disease carriers among individuals with thermolabile hexosaminidase B.

The determination of hexosaminidases A and B in most programmes for Tay-Sachs disease carrier detection is based on their different heat sensitivity (hexosaminidase A is the heat labile isoenzyme). This routine cannot be employed for individuals who also possess a thermolabile hexosaminidase B. In Israel, 0.6% of the screened samples have a labile hexosaminidases B (about 110 each year) and the assessment of their hexosaminidase A activity has hitherto been based on isoenzyme separation by ion exchange chromatography. The latter requires relative large serum samples, and the individuals must usually be reappointed. In order to avoid the thermal treatment we have used the alternative technique, which employs two substrates with different specificities for the two isoenzymes: 1. The fluorogenic substance, 4-methylumbelliferyl-N-acetyl-glucopyranoside, which measures total hexosaminidase activity and 2. the derivative, 4-methylumbelliferyl-N-acetyl glucosamine-6-sulphate, which is considerably more specific toward hexosaminidase A. Hexosaminidase A activity was expressed as a ratio of total activities (the ratio of the assay with 4-methylumbelliferyl-N-acetyl glucosamine-6-sulphate to that with 4-methyllumbelliferyl-N-acetyl-glucopyranoside). Using the results from 65 obligate heterozygotes for Tay-Sachs disease, we established our reference ranges for assigning the genotypes with respect to the Tay-Sachs gene. Comparison of the results from 182 unrelated and randomly chosen sera screened by the ratio method and by heat inactivation, showed a very high correlation (r = 0.996). Sixty eight sera with thermolabile hexosaminidase B were tested by ion exchange chromatography and by the double substrate method, and they yielded identical diagnoses with regard to the Tay-Sachs locus.(ABSTRACT TRUNCATED AT 250 WORDS)

Excision-repair in primary cultures of mouse embryo cells and its decline in progressive passages and established cell lines.

Fibroblasts of mouse embryo cells from early subcultures excise pyrimidine dimers to an extent and at a rate comparable to those observed in human cells. The only apparent difference is that in primary mouse cells dimers are excised in an acid-insoluble form. Dimer excision in mouse embryo fibroblasts declines abruptly after the fourth to the sixth subculture and is not detectable in the permanent cell line 3T3. It is suggested that cessation of excision-repair may be due to genetic repression.

Genetic control of thymus size in inbred mice.

Differences exist among inbred mouse strains in the size of the thymus relative to overall body size. These differences are controlled by several genes acting in different phases of thymus development. After 50 days of age, there is an approximately 2-fold difference in thymus size between C57BL/6J and AKR/J, and other strains (A/J, DBA/2J, BALB/cJ, CBA/J, C3H/HeJ, 129/J, C57BL/ 10J , MA/ MyJ ). The C57BL/6J and AKR/J mice have the larger thymus, and this characteristic is dominant in F1 animals derived from C57BL/6J and A/J strains. Studies on recombinant inbred strains derived from C57BL/6J and DBA/2J ( BXD strains), and C57BL/6J and A/J ( AXB and BXA strains) indicate that this difference is controlled by alleles at one locus, which we have designated Tsz -1 (thymus size 1). In the immediate postnatal period (0-23 days), while the relative size of the thymus is increasing, the thymus size of C57BL/6J mice is large relative to that of A/J mice, but the A/J character is dominant during this period, and this difference appears to be controlled by two genes.

Keratin-9 gene mutation in a family with epidermolytic palmoplantar keratoderma.

BACKGROUND: Epidermolytic palmoplantar keratoderma is an autosomal dominant inherited disorder of keratinization. METHODS: We studied five members of a Jewish family with epidermolytic palmoplantar keratoderma. Genomic DNA was extracted from leucocytes, and exon 1 of the keratin 9 gene was amplified using polymerase chain reaction techniques. RESULTS: The mutation was found in exon 1 of the keratin 9 gene in codon 160. CONCLUSIONS: Like most of the other families with clinical features of epidermolytic palmoplantar keratoderma the mutation is found in exon 1 of the keratin 9 gene.

Prenatal and postnatal studies of a late infantile GM2 gangliosidosis in a family of Syrian origin: a possible B1 variant.

We describe late infantile Tay-Sachs disease with high residual hexosaminidase A activity in two siblings of a Syrian Druze family. The patients' leukocytes had 26% of normal hexosaminidase A activity when tested with the conventional fluorogenic substrate 4-methyl-umbelliferyl-2-acetamido-2-deoxy-beta-D-glucopyranoside (4-MUG) and only about 10% when assayed with the sulfated substrate, 4-methyl-umbelliferal- beta-N-acetyl-glucosamine-6-sulfate (4-MUGS). According to the standard procedure of the heterozygote screening program (employing 4-MUG and heat inactivation), the parents were not diagnosed as an at-risk couple since the father was classified as a noncarrier. However, both parents' levels were clearly within the carrier range on the basis of 4-MUGS. The unique catalytic characteristics of the patients' enzyme forward the assumption that the affected sibs are B1 variants. The parents' enzymatic levels, together with their known consanguinity, might indicate that these patients are homozygotes for the rare mutation and not genetic compounds as has been documented for most of the infantile B1 variants. To the best of our knowledge this is the first reported case of B1 variant in a child of that extraction.

GM2 gangliosidosis B1 variant: biochemical and molecular characterization of hexosaminidase A.

The biochemical properties of hexosaminidase A (HexA) and the coding sequence of the alpha-subunit were examined in a patient of Syrian ancestry with the B1 form of Tay-Sachs disease (TSD). The biochemical characteristics of the variant HexA suggest that both active sites are affected by the mutation(s). Kinetic studies with the beta-subunit specific substrate, 4-methylumbelliferyl-beta-D-N-acetylglucosamine (MUG), revealed a significant difference between the Km values. of normal and variant HexA, while no difference was found when the sulfated substrate MUG-6-sulfate (MUGS), which is specific for the alpha-subunit active site, was used. The Vmax values for both substrates were significantly lower in extracts from B1 variant cells than in control extracts, implying a reduced enzyme level in the variant cells. A noncompetitive inhibitor of the reaction with MUGS, N-acetylglucosamine (NAG), induced a significant inhibition (30%) in the mutant cells only. When MUG was used as substrate, variant HexA was found to be more heat stable (T50 = 170 min) than normal HexA (T50 = 65 min). Furthermore, the mutant cell preparation differed from control in the relation between Hex thermosensitivity and protein concentration in the reaction. Two new mutations were identified in exon 5 of the HexA gene: a C496 to G transversion, which produced an Arg166 -->Gly alteration and a deletion of C498 which generated a shift in the reading frame. The patient was a heterozygote for both mutations even though her parents are first cousins. There is no evidence as yet which of these mutations accounts for the B1 phenotype.

Time-dependent toxicity of drugs used in cancer chemotherapy: separate and combined administration.

Time-dependent toxicity of 3 anti-cancer drugs was demonstrated in BALB/c mice. Cisplatinum, adriamycin and cyclophosphamide were injected at 4 different circadian stages, either together (combined injection) or separately, to different groups of mice. Toxicity was evaluated by body-weight changes, mortality and white blood cell counts. Maximal body-weight loss was caused by the administration of either Cisplatinum or the combination of all 3 drugs at 15.00 hr and 21.00 hr, i.e., 9 and 15 hr after light on (HALO). Only moderate body weight loss was induced when adriamycin was injected at 09.00 hr or at 21.00 hr (3 and 15 HALO). In contrast to Cisplatinum and adriamycin, cyclophosphamide induced no significant change in body weight when injected at either time. The highest level of mortality was caused by the injection of all 3 drugs together at 21.00 hr (15 HALO). No death occurred when drugs were administered separately. The rate of recovery (as assessed by weight regain) also exhibited dependence upon the time of drug administration and was the slowest after injections at 21.00 hr (15 HALO). It appears, therefore, that the time-dependence modes of toxicity and recovery (as assessed by body-weight change) are different. The decrease in white blood cell count also exhibited a time-dependence pattern which differed from that of weight loss and death.

Long ultradian rhythms in red blood cells and ghost suspensions: possible involvement of cell membrane.

Oscillations in glyceraldehyde-3-phosphate dehydrogenase (GAPD) and glucose-6-phosphate dehydrogenase (G6PD) activities were recorded in suspensions of intact human red blood cells (RBCs) exposed to various light regimens. The periods of these oscillations, defined as "long ultradian," ranged between 13 and 18 h regardless of light regimen. The patterns of enzymatic activities were the same when assayed at each time point, in full hypotonic hemolysates, and membrane-free hemolysates. However, if hemolysates were prepared by sonication the activity pattern did not exhibit significant oscillations and the activity was higher than that recorded in hypotonic hemolysates. The observed rhythms may reflect a time-dependent attachment and detachment of enzyme molecules from cell membrane, suggesting that at the bound state the enzyme molecules are (temporarily) inactive. Oscillations with similar long ultradian periods were also observed in Ca++ concentration of suspended RBCs and in the binding of Ca++45 to human RBC ghosts. Treatment of the RBCs with A2C or Diamide before the preparation of the ghosts changed or distorted the rhythmic pattern of Ca++45 binding. These results point to the role of the membrane in processing the long ultradian oscillations. The relation between this type of oscillations to circadian rhythm is discussed.

Screening for fragile X syndrome in women of reproductive age.

We conducted a prospective intervention study of screening for fragile X syndrome in the general population. Antenatal and preconceptional screening were carried out in 9459 women aged between 19 and 44 with no known family history of fragile X syndrome. 80% were tested antenatally. 134 carriers were detected (a frequency of 1 in 70); 130 had a premutation (PM) and 4 had a full mutation (FM). Prenatal diagnosis was carried out in 108 concurrent or subsequent pregnancies among carriers involving 111 fetuses. Nine had an FM, a rate of 1 in 12; two of the affected embryos received the FM directly from the mother and in seven it was the result of expansion from a PM. In all cases with an FM the pregnancy was terminated. In PM carriers there was evidence of a selection against the mutated chromosome with a segregation ratio of 0.40. Owing to the high rate of premutated chromosomes in our population we conclude that screening for fragile X syndrome among women of reproductive age should be more widely available.