A cytogenetic survey of an institution for the mentally retarded: I. Chromosome abnormalities

A cytogenetic survey of 475 patients in an institution for the mentally retarded is reported. The chromosomes of all patients were studied using both a non-banding and a G-banding technique in order to estimate the relative efficiency of the two technique in detecting structural rearrangements of the chromosomes. A total of 57 patients was found to have a chromosome abnormality, including five with a balanced structural rearrangement. The contribution of chromosome aberrations to the etiology of mental retardation is discussed with special emphasis on the contribution of balanced structural rearrangements.     

5′-Cytosine DNA-methyltransferase mRNA levels in hereditary colon carcinoma

 DNA methylation plays an important part in the regulation of gene expression. Alterations in DNA methylation in tumours have been reported and have been used to generate hypotheses about mutagenesis and silencing of tumour suppressor genes. However, the underlying mechanism is still poorly understood, and conflicting data on the levels of overexpression of 5′-cytosine DNA methyltransferase in sporadic colon carcinoma have been published. We used a competitive RT-PCR assay for quantification of mRNA of 5′-cytosine DNA methyltransferase in colon biopsies obtained from patients with hereditary colon carcinoma syndromes and compared the results with those obtained in a control group. No significant difference was found between the flat mucosa of FAP patients and the mucosa of the control group. In FAP and HNPCC patients, the 5′-cytosine DNA methyltransferase mRNA levels of adenomas were significantly higher (P<0.05) than of flat mucosa in the same group, but both showed great variability from patient to patient. Our findings suggest that the mRNA levels of methyltransferase cannot be used as predictive marker for screening in families affected by hereditary colon carcinoma. Received: 20 July 1998 / Accepted: 21 September 1998     

The Effect of Presleep Focal Attention Load on Subsequent Sleep Patterns

The hypothesis that a load on focal attention prior to sleep results in subsequent changes in sleep patterns was investigated. Eight females and 2 males slept in the laboratory for 4 nights: 2 adaptation nights, 1 experimental night preceded by a focal attention load, and 1 control night preceded by relaxed activity. On the experimental night, time in bed, total sleep time, and stage REM sleep were significantly longer than on the control night. The results support the hypothesis and suggest that attention during REM sleep has a unique character.     

Carrier detection in Duchenne and Becker muscular dystrophy Argentine families

In order to offer carrier detection, genetic counseling, and prenatal diagnosis to families with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) in our country, segregation analysis of highly polymorphic short tandem repeats (STR) (dC-dA)n: (dG-dT)n loci was utilized. The risks to females of 15 DMD/BMD families (9 familial and 6 sporadic) were evaluated on STR, pedigree and serum creatine kinase (SCK) data. From the 36 females at risk of being carriers (not including 8 obligate carriers), results of STR analysis were compatible with carrier status in 7 and not compatible in 20. In 9 females, no information regarding carriership was derived from the STR analysis. Prenatal diagnosis is now possible on the carrier females. Previously identified deletions in the central part of the gene were confirmed by STR analysis in 3 families. Five new alleles were identified in Argentine individuals; allele frequencies differed from those of North American people. Results derived from this study are useful for carrier detection and genetic counseling in DMD/BMD. One case of probable mosaicism in an unaffected father was detected on a pedigree basis in a family with DMD patients.     

Variations in the ultrastructure and oxygen consumption of the daughter sporocysts ofCercaria stunkardi Palombi, 1934 andCercaria linearis Stunkard, 1932 (Digenea: Opecoelidae) in chemically defined media

Summary Variations in the oxygen consumption and alterations in the ultrastructure of the body wall in the daughter sporocysts ofCercaria stunkardi andCercaria linearis during maintainance in artificial sea water as compared with those in modified Medium 199, indicate that the latter is an unsatisfactory nutrient medium. Similar changes in oxygen consumption, which suggest endogenous carbohydrate and lipid utilization together with autolysis, occur in the nutrient and non-nutrient media. Autolysis in the body wall of the sporocysts progresses, nearly to complete destruction, with almost equal rapidity in both media. The contained cercariae, however, remain healthy and appear to consume most of the absorbed oxygen.     

Progenitor egress from the bone marrow after allergen challenge: role of stromal cell-derived factor 1alpha and eotaxin

BACKGROUND: CCR3 expression on CD34+ cells mediates migration to eotaxin in vitro. CXCR4 and stromal cell-derived factor (SDF)-1alpha are important for stem cell homing to hemopoietic compartments. OBJECTIVE: To study chemokine-mediated progenitor cell traffic in allergic inflammation. METHODS: Bone marrow (BM) aspirates were obtained at baseline from normal subjects; atopic subjects without asthma; and subjects with asthma before, 5 hours after, and 24 hours after allergen inhalation (dual and early responders). Changes in chemokine receptor expression and migration were assessed. RESULTS: Expression of CXCR4, but not CCR3, on BM CD34+ cells was greater in normal subjects compared with atopic subjects with asthma. Likewise, SDF-1alpha, but not eotaxin, stimulated a greater migrational response by BM CD34+ cells from normal subjects compared with subjects with asthma. For all subjects, a positive correlation was found between intensity of CXCR4 expression and magnitude of CD34+ cell response to SDF-1alpha. Allergen inhalation attenuated both intensity of CXCR4 expression and SDF-1alpha levels in marrow from dual compared with early responders 24 hours postallergen. In contrast, the intensity of CCR3 expression on BM CD34+ cells increased in dual compared with early responders at 24 hours postallergen. In addition, an increase in migrational responsiveness of BM CD34+ cells to eotaxin and a decrease to SDF-1alpha 24 hours postallergen was found in dual responder subjects with asthma. CONCLUSION: After allergen inhalation in subjects with asthma, a downregulation in CXCR4 intensity on BM CD34+ cells and a reduction in BM SDF-1alpha levels may reduce progenitor retention to marrow stroma promoting peripheral egress, possibly mediated by the CCR3/eotaxin axis.     

Interhemispheric sleep EEG asymmetry in the rat is enhanced by sleep deprivation

Vigilance state-related topographic variations of electroencephalographic (EEG) activity have been reported in humans and animals. To investigate their possible functional significance, the cortical EEG of the rat was recorded from frontal and parietal derivations in both hemispheres. Records were obtained for a 24-h baseline day, 6-h sleep deprivation (SD), and subsequent 18-h recovery. During the baseline 12-h light period, the main sleep period of the rat, low-frequency (<7.0 Hz) power in the non-rapid eye-movement (NREM) sleep EEG declined progressively. Left-hemispheric predominance of low-frequency power at the parietal derivations was observed at the beginning of the light period when sleep pressure is high due to preceding spontaneous waking. The left-hemispheric dominance changed to a right-hemispheric dominance in the course of the 12-h rest-phase when sleep pressure dissipated. During recovery from SD, both low-frequency power and parietal left-hemispheric predominance were enhanced. The increase in low-frequency power in NREM sleep observed after SD at the frontal site was larger than at the parietal site. However, frontally no interhemispheric differences were present. In REM sleep, power in the theta band (5.25-8.0 Hz) exhibited a right-hemispheric predominance. In contrast to NREM sleep, the hemispheric asymmetry showed no trend during baseline and was not affected by SD. Use-dependent local changes may underlie the regional differences in the low-frequency NREM sleep EEG within and between hemispheres. The different interhemispheric asymmetries in NREM and REM sleep suggest that the two sleep states may subserve different functions in the brain.