Germline mutations in the neurofibromatosis type 2 tumour suppressor gene

The recent identification of the NF2 tumour suppressor genehas enabled large scale screening for pathological mutationsin the gene. We have sought germline mutations In the NF2 geneby SSCP and heteroduplex analysis of cDNA and genomic DNA samplesfollowed by cloning and sequencing of mutant alleles. In thepresent report we describe 11 putative pathological mutations,including five nonsense mutations, three short insertions ordeletions cauing frameshifts and three missense mutations. Moststop mutations and frameshift mutations were found In Individualsexpressing a severe phenotype while one of the three missensemutations was associated with a mild phenotype. Four unrelatedNF2 patients of the 93 tested were found to have identical nonsensemutations caused by a C to T transition (C169) in a CpG dinucleotide,which is a potential mutational hotspot in the NF2 tumour suppressorgene.     

A comparison of alexithymia in American and Japanese dialysis patients.

A comparison of alexithymia in American and Japanese dialysis patients was performed using the Beth Israel Hospital Questionnaire (BIQ) and the MMPI Alexithymia Scale (MMPI-AS) including structured interviews. No significant differences between the USA and Japan were observed in all dialysis patients with both BIQ and MMPI-AS. However, the alexithymia score in US hemodialysis (HD) patients was significantly lower than that in Japanese HD patients, whereas the alexithymia score in American continuous ambulatory peritoneal dialysis (CAPD) patients was significantly higher than that in Japanese CAPD patients. These results may suggest the possibility that the differences in dialysis policy between USA and Japan have secondary effects on alexithymia, which is one of the psychosomatic factors reflecting self-control ability in dialysis patients.     

Reduction of flurazepam's antiseizure efficacy persists after stress.

Twenty-four hours after mice were forced to swim for up to 10 min in cold (6 degrees C) water, the ability of flurazepam to antagonize the electrical precipitation of seizures was reduced. This stress-induced reduction in flurazepam's antiseizure efficacy persisted for at least 72 h; but was absent 1 week after the single session of swim stress. The data may be relevant to stress-related psychiatric disorders and suggest that the therapeutic efficacy of benzodiazepines may be altered after a severe stress.     

Epidemiology of trauma: frequency and impact of different potentially traumatic events on different demographic groups.

The frequency and impact of 10 potentially traumatic events were examined in a sample of 1,000 adults. Drawn from four southeastern cities, the sample was half Black, half White, half male, half female, and evenly divided among younger, middle-aged, and older adults. Over their lifetimes, 69% of the sample experienced at least one of the events, as did 21% in the past year alone. The 10 events varied in importance, with tragic death occurring most often, sexual assault yielding the highest rate of posttraumatic stress disorder (PTSD), and motor vehicle crash presenting the most adverse combination of frequency and impact. Numerous differences were observed in the epidemiology of these events across demographic groups. Lifetime exposure was higher among Whites and men than among Blacks and women; past-year exposure was highest among younger adults. When impact was analyzed as a continuous variable (perceived stress), Black men appeared to be most vulnerable to the effects of events, but young people showed the highest rates of PTSD.     

Surgical Management of Marfan Syndrome in Children

Between August 1983 and January 1991, seven patients with Marfan syndrome underwent surgery for severe cardiovascular complications. The mean age at presentation was 5.7 months (range 4 to 9 months) in the infant group (n = 3), and 13.3 years (range 10 to 16 years) in a group of older children (n = 4). The primary indications for surgery in the infant group (performed at a mean of 3 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in one patient, and severe mitral valve prolapse with regurgitation in two. In the older group, surgical indications (performed at a mean of 2.8 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in three patients and acute aortic dissection in one. For aortic surgery, a composite valved conduit was used in four patients, and an aortic homograft in one. For mitral valve surgery, mechanical prostheses were used. Ail patients survived the primary operation. Over a mean follow-up of 17.5 patient-years (range 1 to 9 years), two patients in the infant Marfan group went on to further successful surgery (prosthetic mitral valve replacement and aortic root repair with aortic homograft) at a mean interval of 4.3 years after the Initial surgery. Our results suggest that the major cardiovascular risk factors of Marfan syndrome in the young, even in those diagnosed during infancy, have been favorably changed by surgery with an encouraging medium-term outlook. The correct timing of surgery is aided by echocardiography. (J Card Surg 1994;9:50–54)     

Activation of muscle fibers in individual motor units revealed by 2-deoxyglucose-6-phosphate

Motor units of the cat tibialis posterior muscle were selectively activated by prolonged electrical stimulation of functionally isolated motor axons in situ. During the activation, the glucose analog 2-deoxyglucose (DG) was administered systemically. Single muscle fibers were subsequently examined for accumulation of the metabolite 2-deoxyglucose-6-phosphate (DG6P) by an analytical assay and for depletion of glycogen by a PAS glycogen-specific staining reaction (periodic acid Schiff; PAS). In general, levels of DG6P were 20 times greater in unstained (PAS-negative) fibers compared with stained (PAS-positive) fibers. However, some glycogen-depleted fibers, particularly in putative ischemic fascicles of the muscle, did not have elevated DG6P, suggesting that depletion of glycogen is not always a reliable indicator of fiber activation. Furthermore, the PAS-staining reaction was not necessarily indicative of quantitative glycogen levels in single fibers. Thus, this report shows that DG6P accumulation enhances the identification of motor-unit fibers selectively activated via their common motor-nerve axon. Evidence is also presented for differential glucose uptake in muscle fibers of different phenotype, thereby indicating that the DG6P measurement in muscle has broad applicability to the investigation of cellular glucose utilization.     

Effects of preparation techniques on the porosity of acrylic cements

We investigated four acrylic cement preparation techniques for their effects on cement porosity: hand mixing, pressurization in a pneumatic pistol, centrifugation, and vacuum mixing. All the techniques were tested on three types of cement with different viscosity characteristics. The best results were obtained with vacuum mixing using a newly designed experimental system, yielding porosity reductions of 60-80 percent relative to hand mixing. Vacuum mixing with a commercial system was also effective, but to a somewhat lesser extent.

Pressurization and centrifugation had no substantial effect on the overall porosity. Centrifugation led to considerable nonuniformity in the distribution of pores and additives.