Improved estimates of discordance ratios in twin studies

In the study of monozygotic twins relative to disease and risk factors, particular interest focuses on the subset who are discordant for some suspected risk factor (for example, smoking), since such twins constitute a natural case-control pair. In such studies, questionnaires designed to identify the status of all twin pairs are sometimes error prone and can yield misleading estimates of the concordance-discordance ratios. Greater efforts to verify the characteristics of apparently discordant pairs than to verify those of apparently concordant pairs can result in the 'unequal ascertainment' fallacy. Using the results of a questionnaire with known error rates and the 'apparent' frequencies yielded, we present unbiased, maximum likelihood estimates of the 'true' proportions of concordant and discordant pairs. concordant and discordant pairs. We also present approximate covariances among these estimates.     

The relationship between maternal needs and priorities in a neonatal intensive care environment

AIM: The aim of this study was to investigate the nature and organization of maternal needs and priorities in a neonatal unit. BACKGROUND: The relationship between maternal needs and priorities appears to be an under studied area in neonatal nursing. METHODS: A quantitative survey was carried out based on 209 mothers with premature infants. Two self-assessment schedules were used: critical care maternal needs inventory (J. Leske, Heart and Lung 15, 27-42) and a ranking scale. The data were analysed with multivariate analysis. FINDINGS: Data analysis revealed clear priorities in maternal needs. In particular the need for accurate infant related information was a priority for 93% of the mothers. Good communication practices with professionals were also valued. The mothers displayed altruistic behaviour, and self-related needs took second place. It is proposed that maternal needs demonstrate a hierarchical organization. CONCLUSION: It is important for nurses to consider the individual needs of the mothers, simply because the satisfaction of these needs is essential for maternal well-being.     

Steroid trials in the assessment of reversibility of air flow limitation: a survey of current clinical practice of chest physicians

To evaluate how steroid trials are currently used in the assessment of reversibility of air flow limitation, a postal questionnaire was sent to 355 consultant members of the British Thoracic Society working in England and Wales; 253 questionnaires were returned (71% response rate). Two respondents did not undertake steroid trials; of the remaining 251, 75% prescribed 30-40 mg oral prednisolone, with the commonest treatment period being 2 weeks. A high dose steroid inhaler was sometimes used as an alternative by 31% of respondents. Although 71% of respondents made lung function measurements on several occasions before starting steroids and 76% made measurements during treatment, 78% assessed patients on only one occasion at the end of the trials to ascertain its outcome. Weight, blood pressure and glycosuria were measured less frequently after the steroid treatment compared to the pre-trial period. Blood glucose and serum electrolytes were infrequently measured both before and after treatment. Wide variations exist in steroid trial regimens and current practice may neither provide definitive evidence of treatment benefit nor an adequate safeguard for patients against potential side-effects.     

Typifications. The first step for clinical diagnosis in psychiatry

Reigning views on psychiatric nosology regard as "too subjective" certain features of diagnosis which respected psychiatrists have reported and several empirical studies have confirmed. We describe two of these persistent "mysteries" of psychiatric nosology: rapid diagnoses and the praecox feeling. We then demystify these mysteries by explicating the workings of "typification" in the diagnostic process. The criteria of disorders which are provided by classification manuals, such as DSM-III, are shown to presuppose such typifications. Psychiatric typification, although a preconceptual skill, can be rendered fully scientific and objective.     

Microiontophoresis of cocaine, desipramine, sulpiride, methysergide, and naloxone in habenula and parafasciculus

The effects of microiontophoretically applied cocaine, desipramine (DES), sulpiride (SUL), methysergide (METH), and naloxone (NAL) on the responses of physiologically identified single neurons in the habenula (Hab) and parafasciculus thalami nucleus (PF) were examined in rats. Three cell types were identified in both nuclei on the basis of the responses obtained following noxious stimulation that were classified as "nociceptive-on," "nociceptive-off," and "nonnociceptive" cells. Administration of cocaine generally resulted in a decrease in the firing rate of nociceptive-on and nonnociceptive neurons in both Hab and PF. In contrast, cocaine generally induced an excitation in the baseline firing of the nociceptive-off cells. Cocaine application concomitant with noxious stimulation prevented the evoked responses of the nociceptive-on and the nociceptive-off cells. DES, when applied alone, was found to induce excitation in neuronal discharge of all three cell types in both sites. Combined application of cocaine with DES resulted in no observable change in discharge frequency for the nociceptive-on and nonnociceptive cells, while inducing an additive excitatory effect on the nociceptive-off cells. SUL, in contrast, induced no observable effect on baseline firing when given alone, yet consistently antagonized cocaine-induced effects on all three cell types. Finally, METH and NAL induced no effects on baseline firing or cocaine-induced modifications in neuronal discharge frequency.     

Delayed oligodendrocyte degeneration induced by brief exposure to hydrogen peroxide.

An in vitro model system of cultured oligodendrocytes was used to determine the susceptibility of these cells to oxidative stress induced by 15 min exposure to millimolar concentrations of hydrogen peroxide (H2O2). Following the exposure, the cells were incubated in normal growth medium, and analyzed at different time points. Although no cell loss was observed during the exposure period, there was a progressive depletion of adherent cells during the postexposure period as seen from either the number of recoverable nuclei, or from total RNA content of the cultures. Both the rate and the extent of cell deletion was directly dependent on H2O2 concentration. Cell death was preceded by structural alterations in the nuclear envelope resulting in "fragile" nuclei which disintegrated during isolation. Northern blot analysis showed that the expression of myelin-specific genes was rapidly downregulated in H2O2-treated cells. On the other hand, the expression of antiapoptotic gene, bcl-2 featured massive but transient upregulation. Oligodendrocyte degeneration also featured genomic DNA degradation into high molecular weight fragments, which are likely to represent cleaved chromosomal loops. The results demonstrate vulnerability of oligodendrocytes to oxidative stress that induces rapid degeneration and ultimately leads to delayed cell death. This feature is highly relevant to oligodendrocyte damage and depletion following ischemic, traumatic, or inflammatory insults to the central nervous system (CNS).     

Increased noradrenergic activity in prefrontal cortex slices of an animal model for attention-deficit hyperactivity disorder--the spontaneously hypertensive rat

Spontaneously hypertensive rats (SHR) are used as a model for attention-deficit/hyperactivity disorder (ADHD) since SHR are hyperactive and they show defective sustained attention in behavioral tasks. Using an in vitro superfusion technique we showed that norepinephrine (NE) release from prefrontal cortex slices of SHR was not different from that of their Wistar-Kyoto (WKY) control rats when stimulated either electrically or by exposure to buffer containing 25 mM K(+). The monoamine vesicle transporter is, therefore, unlikely to be responsible for the deficiency in DA observed in SHR, since, in contrast to DA, vesicle stores of NE do not appear to be depleted in SHR. In addition, alpha(2)-adrenoceptor mediated inhibition of NE release was reduced in SHR, suggesting that autoreceptor function was deficient in prefrontal cortex of SHR. So, while DA neurotransmission appears to be down-regulated in SHR, the NE system appears to be under less inhibitory control than in WKY suggesting hypodopaminergic and hypernoradrenergic activity in prefrontal cortex of SHR. These findings are consistent with the hypothesis that the behavioral disturbances of ADHD are the result of an imbalance between NE and DA systems in the prefrontal cortex, with inhibitory DA activity being decreased and NE activity increased relative to controls.     

Baseline and time-averaged fluid removal affect technique survival in peritoneal dialysis in a non-linear fashion

AIM: The longevity of peritoneal dialysis (PD) is limited by technique failure and patient mortality. The authors assessed the influence of baseline and time-averaged fluid removal on patient, technique and death-censored technique survival. METHODS: Peritoneal and total fluid removal was measured 1 month after commencing PD, then 6 monthly, in 225 incident patients (mean age 55.3+/-15.8 years, 52% male). A Cox proportional hazards model regression analysis was performed to identify variables independently predictive of technique and patient survival. RESULTS: Seventy (31.9%) patients were transferred to haemodialysis and 39 (17.63%) died. Technique survival was greatest in the middle tertile of baseline total fluid removal (mean survival time 3.5 vs 2.5 and 2.2 years for the lower and upper tertiles, respectively, log rank 6.5, P=0.039). The middle tertile of both baseline and time-averaged total fluid removal were significant predictors of PD survival (adjusted hazard ratio (HR) 0.476, 95% CI 0.286-0.795, P=0.005 relative to the upper tertile and HR 0.573, 95% CI 0.350-0.939, P=0.027 for baseline and time-averaged, respectively). Other significant variables on multivariate analysis were body mass index (HR 1.044 per kg/m2, 95% CI 1.005-1.084, P=0.028), creatinine (HR 0.999 per micromol, 95% CI 0.998-1.000, P=0.048) and residual Kt/V (HR 0.418, 95% CI 0.233-0.747, P=0.003). Patient survival was not affected by fluid removal. CONCLUSION: Patients with moderate total fluid removal both at baseline and throughout their PD career have improved technique survival. Attention should be paid to optimizing total fluid removal.