Chromosome mapping of Rett syndrome: a likely candidate region on the telomere of Xq.

Rett syndrome (RS) is a disease of neurological development. First reported 30 years ago in 1966, its biological and genetic basis remains obscure. RS is commonly thought of as an X linked dominant disorder lethal to hemizygous males. The few familial cases would arise through mosaicism or because of occasional females failing to manifest the disorder through skewed X inactivation in relevant cell types. We have one family where the mother and daughter are affected with RS, and which can be explained according to this hypothesis. If the alternative proposal of Thomas (1996) is correct, that the lack of males affected by such disorders is the result of a high male to female ratio of germline mutations rather than of gestational lethality, then the RS gene should be located on the grandpaternal chromosome. Genomic screening with markers covering the whole X chromosome has been performed. Studies using multiple informative markers indicate that the RS locus is likely to be located close to one of the X chromosome telomeres. Further investigations in eight additional families suggest the most likely region for the RS gene to be is the distal part of Xq (Xq28).     

Pulmonary sequelae of long-term ventilation of very low birth weight premature infants. Results of a follow-up study of 6-to-9-year-old children

Fifty six children with a birth weight of less than 1500 g and gestational age less than 34 weeks were studied at a mean age of 7.7 years. All had required mechanical ventilation, 36 suffered from hyaline membrane disease, 17 from atelectasis and three from pneumonia. Of these patients 37 developed broncho-pulmonary dysplasia (BPD). The study included skin prick test, measurement of ciliary beat frequency, chest X-ray, whole-body plethysmography and histamine challenge. Eight patients suffered from recurrent pulmonary infections up to the age of 4 years. Eleven children had a positive skin prick test. Three suffered from allergic asthma and six from hay-fever. The family history of atopy in these premature infants was no different from that of the general population. Ciliary beat frequency was normal in all cases (frequency: 11.8 +/- 1.8 Hz). In 34 patients X-rays showed minimal changes (peribronchial thickening n = 6, mild emphysema n = 28). Pulmonary function was normal except for an increase of thoracic gas volume which was correlated to grade of BPD according to Northway. There was a significant correlation between oxygen-score and radiological stage of BPD (r = 0.7). Histamine challenge showed hyperresponsiveness in 53% of the children. Eight patients showed a threshold similar of mild asthma (less than 1000 micrograms histamine per ml). The degree of airway hyperreactivity was correlated to the grade of BPD (r = 0.7; p less than 0.01) and the oxygen-score (r = -0.63; p less than 0.05). The oxygen-score may be considered a predictor of hyperresponsiveness and pulmonary outcome in later childhood.     

Chronic maxillary sinusitis. Energy metabolism in sinus mucosa and secretion

The energy metabolism in maxillary sinus mucosa and secretion from 41 patients with, in most cases, recurrent or chronic sinusitis was studied and compared with that in mucosal samples from patients with no previous history of sinus abnormality or infection. In freeze-dried samples, glucose and lactate were measured by enzymatic assays and adenine nucleotides by HPLC. In chronic sinusitis the lactate concentration in the mucosa was increased, probably as a result of increased glycolysis or of impaired diffusion within the mucosa. The lactate concentrations in purulent and non-purulent secretions were 16.3 and 1.1 mmol x kg-1 w.w., respectively. The higher concentration in the purulent secretion was due mainly to leucocyte metabolism. The adenine nucleotide contents in the mucosa were similar in all groups studied. Anaerobic bacteria were isolated only in secretions with a high lactate concentration.     

Contrasting subjective judgement and objective tests in the hearing-impaired.

The Hearing Performance Inventory (HPI, Giolas et al., 1979) was used to measure 21 moderately hearing-impaired persons' subjectively experienced problems in everyday listening. The HPI rating data show that the greatest problems are experienced on the dimensions 'understanding speech without visual cues', and 'perceived intensity' of sounds. 'Understanding speech with visual cues' has a high positive correlation with both 'social situation' and 'work situation' dimensions, whereas 'understanding speech without visual cues' correlates with 'social' and 'personal situation'. The correlations between the HPI and actual performance in the speechreading tests, and between the HPI and cognitive abilities that were assumed to be critical for speechreading ability, were also examined. It was found that vocabulary size, highly intercorrelated with guessing, was important to the 'social situation' dimension on the HPI. Guessing also constitutes an important cognitive predictor of speechreading skill. However, none of the HPI dimensions was directly related to objective communicative competence. Given the limitations of speechreading training, the data suggest that vocabulary and social skills should be focused on during communicative training.     

Direction-dependent amplification of the human outer ear

The transfer function of the outer ear in humans was determined by using the impulse technique. Signals were delivered from 325 or 393 positions on an imaginary sphere surrounding the experimental subject. Changes of sound pressure level in the ear canal show that certain frequency bands are amplified maximally if they impinge onto the ear from certain directions. For some frequency bands there are two directions of sound incidence that cause best amplification in the ear canal. The directionality of the human pinna appears to increase at higher frequencies. The amount of amplification by the outer ear of frequencies between 2 and 15 kHz was also determined by measuring the free-field transfer function.     

Risks of a cartilage-bone bank with reference to HIV infection

Allogenic transplants have an established place in reconstructive procedures. For years it has been suspected that lyophilized dura mater can transmit Creutzfeld-Jakob disease. HIV infection with fully manifest AIDS and a mortality of up to 100% is now also increasing in significance. It is necessary to assess the risk of transferring HIV with allogenic transplants because HIV passes into the cell via specific surface receptors and is integrated within the chromosome. Experimental data on disinfection and sterilization of allogenic transplants stored within chromosomes and their inactivation are not available. Allogenic transplants are only used in operations for life-threatening disease. As a rule, these are elective operations which must meet the highest safety standards, also with regard to the danger of infection. Collaboration with a transplantation team is essential.     

Serological study of the incidence of murine viruses in a population of small wild rodents (Microtus pennsylvanicus Ord, 1815)]

The results of a serological survey of a free-living population of meadow voles (Microtus pennsylvanicus) in Pinawa, Manitoba (Canada) showed that these animals possessed antibodies to six of the eleven viruses tested for, namely: reovirus type 3, murine encephalomyelitis agent, ectromelia virus, murine adenovirus, murine hepatitis virus and lymphocytic choriomeningitis virus. The significant increase in the number of individuals possessing specific antibodies suggests that these viruses, or related viruses, may be responsible for the decline in the population studied.     

Thermally crosslinked rigid-rod aramids, 2. Fiber spinning and fiber properties

Fibers of three rigid-rod aromatic copolymers, produced by polycondensation of 2,2,6,6-tetraoxo-1,3,5,7-tetrahydro-2,6-dithia-s-indacene-4,8-diamine (DSDA), p-phenylenediamine and terephthaloyl dichloride, were spun from nematic solutions and characterized by wideangle X-ray-diffraction (WAXD) measurements and mechanical tests. A post-spin heat treatment was employed to improve the low degrees of orientation and crystallinity exhibited generally by the untreated fibers. The dominating crystal structures of the copolymers are similar to “modification I” of the well known fibers from poly(p-phenyleneterephthalamide) (PPTA). Thermally induced crosslinking of the fibers in the solid state was performed simultaneously with post-spin treatment. The influence of the annealing conditions on the mechanical fiber properties and the molecular order in the fibers was also investigated. All mechanical parameters were time-dependent, probably due to the generation of stable radicals during heat treatment. The radicals may give rise to chain scission.     

Intramedullary epidermoid cyst of the cervical spinal cord associated with an extraspinal neuroenteric cyst: case report.

A 4-year-old girl presented with an intramedullary epidermoid cyst of the cervical spinal cord. The clinical, radiological, and surgical features and a brief critical review of the literature are included in this report. The cyst contents were removed totally in two operations. The child had a coexisting neuroenteric cyst in the posterior mediastinum. To our knowledge, this coexistence has not been previously reported. Contemporary imaging modes and prospects of the surgical treatment are discussed.