Trisomy 22 and intersex

Complete trisomy 22, with or without mosaicism, has been reported as a distinct syndrome. In this report an infant is described who was externally male but with female rudimentary internal organs and whose karyotype was 47,XX+22.

Fragile-X syndrome in North East Essex: towards systematic screening: clinical selection

A systematic screening for fragile-X syndrome, using various clinical criteria to preselect for cytogenetic testing, was performed throughout the North East Essex Health District on 1100 people attending three different local services for people with learning disability. The selection procedure used varied from a gestalt impression to head, ear and testis measurement depending on the setting. Fifty-nine males and five females who met the selection criteria went on to have chromosome studies. Of these, 23 males and one female were positive (more than 4% positive cells). They came from 19 families. Whilst the true prevalence of fragile-X syndrome is not known in the district, at a minimum, it contributed 3.2% of the institutionalized males (health authority care), 4.4% of the boys and 2.1% of the girls attending special schools for severe learning disability, 7.9% of the boys attending schools for mild learning disability (Local Education Authority), and 3.5% of men attending the two adult training centres within the district (social services). These figures compare well with the yield from reported surveys in which all individuals without a known diagnosis were tested cytogenetically.

Molecular maturation of cell adhesion systems during mouse early development

During cleavage, the mouse embryo expresses a variety of cell adhesion systems on its cell surfaces. We have reviewed biogenetic and assembly criteria for the formation of the uvomorulin/catenin, tight junction and desmosome adhesion systems as the trophectoderm differentiates. Each system reveals different mechanisms regulating molecular maturation. Adhesion processes contribute to the generation of distinct tissues in the blastocyst by modifying the expression pattern of blastomeres entering the non-epithelial inner cell mass lineage. Cell adhesion also influences the spatial organisation, but rarely the timing of expression, of proteins involved in trophectoderm differentiation.

The BBZ/Wor rat: clinical characteristics of the diabetic syndrome

The BBZ/Wor rat is a model of obesity and autoimmune diabetes mellitus developed by crossing the BB/Wor and Zucker rats. We studied circulating glucose and insulin levels, islet morphology and lymphocyte subsets in lean and obese BBZ/Wor rats before and after the onset of diabetes, and studied the clinical course of diabetes in animals after interruption of exogenous insulin therapy. Lean BBZ/Wor rats developed insulin-dependent diabetes and died in ketoacidosis within 1 week after cessation of insulin injections. Diabetes also developed in obese rats, but these animals were not insulin-dependent and survived for months without insulin therapy. The islets of the lean diabetic rats revealed complete destruction of pancreatic beta cells and plasma insulin levels were virtually undetectable. In contrast, the islets of the obese rats revealed insulitis and substantial beta-cell loss, however autoimmune beta-cell destruction was incomplete, and residual beta cells were presumably responsible for the presence of measurable levels of plasma insulin and the long-term survival of obese diabetics without insulin therapy. Obese rats were hyperinsulinaemic, developed diabetes significantly earlier, and with a greater incidence than lean rats, suggesting a possible relationship between enhanced beta-cell metabolic activity and immune destruction. Obese males became diabetic more frequently and at an earlier age than obese females and lean rats of both sexes, suggesting a role for gender in the pathogenesis of diabetes. We conclude that the BBZ/Wor rat is a unique animal model for investigating the interaction of obesity, beta-cell metabolism, autoimmune insulitis and genetic predisposition to diabetes.

Prevalence of the fragile X anomaly amongst autistic twins and singletons

Early screening studies of autistic individuals suggested that up to one-quarter of cases were associated with the Fragile X anomaly. Recent studies find that the usual behavioural phenotype of the Fragile X anomaly is distinct from autism as usually defined, and that a variety of methodological factors contribute to the variability of the prevalence estimates. We report the prevalence of the Fragile X anomaly, using strict cytogenetic criteria, in a large sample of autistic individuals whose diagnosis was confirmed using a standardised diagnostic instrument. The anomaly was detected in 1.6% of tested autistic individuals from a combined sample of: autistic twins; clinic attenders; and, individuals from families multiplex for autism or related cognitive phenotypes. The anomaly was not detected in greater than 2.5% of any of the constituent samples and accounted for only a small proportion of the genetic influences amongst concordant twins and multiplex families. The anomaly was detected in 5% of the 40 tested autistic females, confirming reports that the prevalence of the anomaly is similar amongst autistic individuals of both sexes.

Acute arterial occlusion of the lower extremity

Acute arterial occlusion of the lower extremity occurs when blood supply from the lower limbs is abruptly cut off. Prompt evaluation and treatment are required to prevent irreversible damage. Differentiation between embolic and thrombotic sources is needed to initiate appropriate therapy. Although different types of occlusion require similar preoperative and postoperative considerations, the specific treatments vary. With a thorough understanding of the causes, signs and symptoms, treatment, and nursing management of acute arterial occlusion, the nurse can assist in the prevention of potentially severe complications.

NMDA-receptor mediated electrical epileptogenesis in the organotypic culture of rat hippocampus

Extracellular field recordings were made in CA1 in the hippocampal explant cultures in oxygenated artificial cerebrospinal fluid. Schaffer collaterals were stimulated with 1-s trains of 60 Hz pulses every 10 min. Seizures were reliably elicited with progressive lengthening over 1-2 h. D-APV, an N-methyl-D-aspartate (NMDA) antagonist, stereoselectively blocked the development of seizures. Thus we have demonstrated that in vitro epileptogenesis occurs in hippocampal explant cultures through NMDA receptor mediated mechanisms.

Antenatal maternal serum screening for Down's syndrome: results of a demonstration project

OBJECTIVES

To assess the implementation of antenatal screening for Down's syndrome in practice, using individual risk estimates based on maternal age and the three serum markers: alpha fetoprotein, unconjugated oestriol, and human chorionic gonadotrophin.

DESIGN

Demonstration project of Down's syndrome screening; women with a risk estimate at term of 1 in 250 or greater were classified as "screen positive" and offered diagnostic amniocentesis.

SETTING

Hospital and community antenatal clinics in four health districts in London.

SUBJECTS

12,603 women of all ages with singleton pregnancies seen between February 1989 and the end of May 1991, with follow up of the outcome of pregnancy completed to the end of 1991.

MAIN OUTCOME MEASURES

Uptake of screening, detection rate for Down's syndrome, false positive rate, odds of being affected given a positive result, and uptake of amniocentesis in women with positive screening results, together with the costs of the screening programme.

RESULTS

The uptake of screening was 74%. The detection rate was 48% (12/25), and the false positive rate was 4.1%, consistent with results expected from previous work based on observational studies. There was a loss of detection due to the selective use of ultrasound scans among women with positive screening results. One affected pregnancy occurred among 205 reclassified as negative; this illustrated the danger of false negatives occurring in this group and lends weight to the view that if an ultrasound estimate of gestational age is used it should be carried out routinely on all women rather than selectively among those with positive results. The estimated cost of avoiding the birth of a baby with Down's syndrome was about 38,000 pounds, substantially less than the lifetime costs of care.

CONCLUSION

Antenatal maternal serum screening for Down's syndrome is effective in practice and can be readily integrated into routine antenatal care. It is cost effective and performs better than selection for amniocentesis on the basis of maternal age alone.

Miller-Dieker syndrome with ring chromosome 17

A girl presented at 6 weeks of age with failure to thrive and arching of the back. She had various dysmorphic features, hepatosplenomegaly, and developmental delay. The electroencephalogram and cranial ultrasound were abnormal, and a computed tomogram showed lissencephaly and apparent agenesis of the corpus callosum. Because of frequent aspiration she became oxygen dependent. She later developed intractable convulsions and died at the age of 9 months.

Influence of environmental viral agents on frequency and tempo of diabetes mellitus in BB/Wor rats

Elimination of environmental viruses by cesarean derivation of the University of Massachusetts colony of BB/Wor rats increased the frequency and accelerated the tempo of spontaneous diabetes among diabetes-prone (DP) rats. In contrast, the viral-antibody-free (VAF) environment did not alter the resistance of pre-VAF diabetes-resistant (DR) rats to spontaneous and RT6+ T-lymphocyte-depletion-induced diabetes. Pre-VAF and VAF rats have essentially the same lymphocyte subsets, and VAF-DP rats are susceptible to the adoptive transfer of diabetes and to the diabetes-accelerating effects of polyinosinic-polycytidylic acid injections. These results suggest that the presence of environmental viral pathogens may act to inhibit effector cell function in lymphopenic DP rats while enhancing effector cell activity in nonlymphopenic DR rats.

A spoonful of competence helps the medicine go down

The Organisation Development Consultancy based in the training department of the North Western RHA has been involved recently in a variety of projects researching into management competencies. This article outlines the findings from a project undertaken at Tameside and Glossop HA. The aim of the research was to provide an information base on which to build an appropriate recruitment and selection strategy and training and development policy for the continued future development of the district.

De novo deletion of Xp22.2-pter in a female with linear skin lesions of the face and neck, microphthalmia, and anterior chamber eye anomalies

A female infant is described with an unusual combination of eye and skin findings. Raw linear skin lesions on the face and neck were present at birth, healing to leave pigmented streaks. In addition she had left sided microphthalmia and bilateral sclerocornea. Chromosome analysis showed a terminal deletion of the short arm of the X chromosome (Xp22.2--pter). Clinical findings were similar to three previously described children with translocations involving Xp22.3. The condition probably represents a new syndrome distinct from incontinentia pigmenti and Goltz syndrome.

Ultrasound fetal femur length measurement in the screening for Down's syndrome

The fetal femur length determined by an ultrasound examination at between 13 and 39 weeks gestation in 83 pregnancies associated with Down's syndrome was statistically significantly less than the expected value for pregnancies with the same biparietal diameter examined in the same ultrasound department (P less than 0.0001). Expected values were based on linear regressions of femur length on biparietal diameter in 1340 control pregnancies from 27 ultrasound departments. The median value for the affected pregnancies was 0.94 times the expected value (95% CI 0.92 to 0.97). Eleven per cent of affected and 1.4% of control pregnancies had values less than or equal to 0.85 times the expected. The reduction in femur length in affected pregnancies was not related to biparietal diameter or to maternal age. Fetal femur length may be useful as an ancillary screening variable in the antenatal screening for Down's syndrome.

Effect of kindling on potassium-induced electrographic seizures in vitro

The properties of high [K+]o-induced spontaneous bursting and electrographic seizures in hippocampal slices prepared from rats subjected to kindling from either the lateral entorhinal cortex or the angular bundle were compared to those in control slices. Kindling enhanced the frequency of K+-induced burst-firing in the CA3 region and the duration of triggered bursts in the dentate gyrus, as previously reported. However, kindling had no influence on the characteristics or occurrence of electrographic seizures in the CA1 region of slices bathed in elevated [K+]o. In addition, the development of electrographic seizures in slices from control animals did not require a preconditioning period of burst input from the CA3 region.

Genetic studies in inbred BB/Wor rats. Analysis of progeny produced by crossing lymphopenic diabetes-prone rats with nonlymphopenic diabetic rats

BB/Wor diabetes-prone (DP) rats are lymphopenic and frequently develop insulin-dependent diabetes. Diabetes-resistant (DR) BB/Wor rats are not lymphopenic and become diabetic rarely and at a significantly younger age. To examine the genetic basis for diabetes, lymphopenia, and age at onset of diabetes among inbred BB/Wor rats, we crossed nonlymphopenic diabetic rats with lymphopenic DP animals and studied F1, F2, and backcross progeny. F1 rats were neither diabetic nor lymphopenic. Diabetes (both types) and lymphopenia reappeared among F2 rats, confirming the permissive association of diabetes and lymphopenia and the recessive nature of both. The absence of diabetes in F1 rats also suggested that the combination of genes responsible for diabetes among lymphopenic and nonlymphopenic rats may be distinct. Nonlymphopenic parental, F1, and F2 rats revealed normal lymphocyte subsets, including CD8+ and RT6+ T-lymphocytes. Lymphopenic parental and F2 rats revealed the absence of CD8+ and RT6+ cells, indicating that these T-lymphocyte abnormalities of lymphopenic DP rats segregate with the lymphopenia gene. The distribution of the ages at onset of diabetes among F2 lymphopenic and F2 intercross rats was significantly earlier than among lymphopenic parental and backcross animals, suggesting that the age of diabetes onset is a heritable trait and that the gene(s) or genetic modifier(s) responsible for the earlier onset of F2 diabetes was acquired from the nonlymphopenic parents. Our genetic studies also confirmed the observations that the 2- and 7-kilobase Bam HI fragments of the MHC class I region do not correlate with diabetes or lymphopenia.

Delayed microhyphaema with intraocular lenses: a retrospective study of eight patients

Eight patients with delayed microhyphaema were identified from a computer data base of 1209 patients who had had cataract extraction with Binkhorst 4-loop intraocular lens insertion. Five cases were recurrent. The cases were examined to try and identify an underlying cause. No single cause was identified, but trauma, hypertension, and oral anticoagulants were found to be associated. Some episodes were asymptomatic. The wide variety of surgical technique and style of lens with which this complication has been reported implies multiple causative factors. The source of the bleeding and its management are discussed.

The association of Angelman's syndrome with deletions within 15q11-13

The inheritance of Angelman's syndrome, a disorder characterised by mental retardation, epilepsy, ataxia, and a happy disposition, is debated because affected sibs occur less frequently than expected with autosomal recessive inheritance. After discovering two unrelated patients with a small deletion of the proximal long arm of chromosome 15, 10 further patients with Angelman's syndrome were reassessed. Five had apparently normal karyotypes, four had a deletion within 15q11-13, and one had a pericentric inversion, inv(15)(p11q13) involving the same chromosomal region. In the latter case, the healthy mother had the same pericentric inversion, indicating that the patient also had a submicroscopic mutation on his other chromosome 15. These data map the Angelman locus to 15q11-13 and suggest that de novo visible deletions (associated with a low recurrence risk) and autosomal recessively inherited cases combine to give an overall sib recurrence risk of less than 25%.