Variations in the incidence of schizophrenia: Data versus dogma

The schizophrenia research community has shared a belief that the incidence of schizophrenia shows little variation. This belief is related to the dogma that schizophrenia affects all individuals equally, regardless of sex, race, or nationality. However, there is now robust evidence that the incidence of schizophrenia is characterized by substantial variability. There is prominent variation in the incidence of schizophrenia between sites. The incidence of schizophrenia is significantly higher in males than in females (male:female ratio = 1.4). Migrants and those living in urban areas have a higher incidence of schizophrenia. The incidence of schizophrenia has fluctuations across time. In addition, the prevalence of schizophrenia is also characterized by prominent variation. The realization that schizophrenia is characterized by rich and informative gradients will serve as a catalyst for future research.

Rapid screening of 4000 individuals for germ-line variations in the BRAF gene

Background: The BRAF gene is frequently somatically altered in malignant melanoma. A majority of variations are at the valine 600 residue leading to a V600E substitution that constitutively activates the kinase. We screened 4000 patient and control DNAs for germ-line variations at the valine 600 residue. Methods: We developed a novel assay by adapting single-base variation assays and software for MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry to screen for all 5 reported variants at codon 600 of the BRAF gene. We screened a case-control collection comprising samples from 1082 melanoma patients and 154 of their unaffected relatives from 1278 families and from 2744 individuals from 659 unselected twin families with no history of melanoma. A panel of 66 melanoma cell lines was used for variation-positive controls. Results: All melanoma cell lines that we had found previously to carry a codon 600 variation were verified in this study. Three of the 4 possible variants (V600E n = 47, V600K n = 2, V600R n = 1) were detected, but no case of V600D was available. No germ-line variants were found in the samples from the 3980 melanoma patients or from the control individuals. Conclusions: This new assay is a high-throughput, automated alternative to standard sequencing and can be used as a rapid initial screen for somatic variants associated with melanoma. Germ-line variants at valine 600 are unlikely to exist and do not contribute to the reported role of the BRAF gene in melanoma predisposition. (c) 2006 American Association for Clinical Chemistry.

Socio-demographic variations in walking for transport and for recreation or exercise among adult Australians

Background: Walking is integral to strategies to promote physical activity. We identified socio-demographic variations in walking for transport, and for recreation or exercise. Methods: Representative population data (n = 3392) from Australia were collected using computer assisted telephone interviewing, to examine adults’ participation in moderate- or brisk-paced walking for transport and walking for recreation or exercise; walking “sufficient” to meet the current public health guideline (> 150 min/wk); and, the contributions of total walking to meeting the guideline for total physical activity. Results: Rates of sufficient walking for transport (10% for men, 9% for women) were lower than those for walking for recreation or exercise (14% for both genders). Few socio-demographic differences emerged. Men over age 60 y were significantly less likely (OR = 0.40) to walk for transport; men age 45 to 59 y were more likely (OR = 1.56) to walk for recreation or exercise. Walking contributed more toward meeting the current public health guideline among women (15% to 21%) than among men (6% to 8%). Conclusions: There is potential for socially equitable increases in participation, through a focus on both walking for transport and on walking for recreation or exercise; attention to gender differences would be helpful.

Transient cardiac ischaemia and abnormal variations in systemic blood pressure in unselected primary open angle glaucoma patients

To investigate the relationship between the occurrence of transient cardiac ischaemic episodes and variations in the ambulatory 24-h blood pressure and heart rate measurements in a group of unselected glaucoma patients.

Quantitative variations in the pathology of 11 cases of variant Creutzfeldt-Jakob disease (vCJD)

Quantitative variations in the density and distribution of the vacuolation ('spongiform change'), surviving neurons, and prion protein (PrP) deposits were studied in eight brain regions from 11 cases of variant Creutzfeldt-Jakob disease (vCJD). Principal components analysis (PCA) was used to study the similarities and differences between cases and to identify the neuropathological variables which could best account for these variations. Two principal components (PC) were extracted from the data accounting in total for 93.4% of the variance; the majority of the variance (90%) being associated with PC1. Some clustering of the 11 cases in relation to PC1 and PC2 was evident. The densities of the vacuolation in the occipital cortex and the molecular layer of the cerebellum were positively and negatively correlated, respectively, with PC1. No significant variation between cases was associated with PrP deposition. These data suggest that vCJD cases have a consistent neuropathological profile characterised by the presence of vacuolation, neuronal loss and PrP deposition in the form of florid and non-florid deposits. However, there are quantitative variations between cases in the development of the vacuolation especially affecting the occipital cortex and cerebellum. © 2002 Elsevier Science Ireland Ltd. All rights reserved.

Using empirical evidence of variations in worker performance to extend the capabilities of discrete event simulations in manufacturing

Discrete event simulation of manufacturing systems has become widely accepted as an important tool to aid the design of such systems. Often, however, it is applied by practitioners in a manner which largely ignores an important element of industry; namely, the workforce. Workers are usually represented as simple resources, often with deterministic performance values. This approach ignores the potentially large effect that human performance variation can have on a system. A long-term data collection exercise is described with the aim of quantifying the performance variation of workers in a typical automotive assembly plant. The data are presented in a histogram form which is immediately usable in simulations to improve the accuracy of design assessment. The results show levels of skewness and range which are far larger than anticipated by current researchers and practitioners in the field.

Cross-cultural variations in climate for autonomy, stress and organizational productivity relationships:A comparison of Chinese and UK manufacturing organizations

Cross-cultural researchers have questioned the extent to which European–American management practices can be transported to major markets in Asia, such as the People's Republic of China. Applying employee involvement theory, we examined the relationships between climate for autonomy, work demands climate, employee stress and organizational productivity in a cross-national study of 51 UK and 104 Chinese manufacturing organizations. We predicted and found that climate for autonomy was positively and negatively related to stress in the Chinese and UK contexts, respectively. The interaction of climate for autonomy and work demands climate was significant: climate for autonomy was positively related to organizational productivity only when work demands climate was low.