Contour completion through depth interferes with stereoacuity

Local disparity signals must interact in visual cortex to represent boundaries and surfaces of three-dimensional (3D) objects. We investigated how disparity signals interact in 3D contours and in 3D surfaces generated from the contours. We compared flat (single disparity) stimuli with curved (multi-disparity) stimuli. We found no consistent differences in sensitivity to contours vs. surfaces; for equivalent amounts of disparity, however, observers were more sensitive to flat stimuli than curved stimuli. Poor depth sensitivity for curved stimuli cannot be explained by the larger range of disparities present in the curved surface, nor by disparity averaging, nor by poor sensitivity to the largest disparity in the stimulus. Surprisingly, sensitivity to surfaces curved in depth was improved by removing portions of the surface and thus removing disparity information. Stimulus configuration had a profound effect on stereo thresholds that cannot be accounted for by disparity-energy models of V1 processing. We suggest that higher-level 3D contour or 3D shape mechanisms are involved.     

Effects of educational attainment and occupational status on cognitive and functional decline in persons with Alzheimer-type dementia

Researchers have suggested that educational attainment and occupational status--indicators of cognitive and/or neurologic "reserve"--can help persons compensate for clinical manifestations of Alzheimer's disease (AD), such as the rates of cognitive and functional decline. The effects of educational attainment on rates of decline could be "direct" independent of occupational status), "indirect" (working through occupational status), or both. We used multilevel analysis for repeated measures to study the effects of educational attainment and occupational status on rates of decline in cognition (Mini-Mental State Examination, MMSE) and function (Cleveland Scale for Activities of Daily Living). Subjects included persons with "probable" or "possible" AD, drawn from our Alzheimer's Disease Research Center registry (N = 482 in the analysis of cognitive decline, and N = 450 in the analysis of functional decline). When controlling for year of birth, gender, ethnicity, and duration of illness, we found that there was an inverse relationship between number of years of education and rate of decline in MMSE, but effects of occupational status were not significant. This implies a "direct" effect of education on decline in MMSE, but no "indirect" effect through occupational status. Neither educational attainment nor occupational status affected rate of decline in functional ability. We conclude that education slows the rate of cognitive decline in persons with AD, but not through its impact on occupational status. Thus, the protective effects of reserve may be established early in life, before people enter the workforce.     

The changing nature of murder in Russia

The death rate from homicide in Russia increased rapidly during the 1990 s. It is now about 20 times higher than in western Europe and is among the highest recorded anywhere in the world. However, this issue has received little attention so far from public health researchers or policymakers.This paper describes the changing nature of homicide during the 1990 s in Russia as a whole and, in more detail, in the Udmurt Republic. The study uses data from three sources: routine mortality data for Russia from 1970 to 1999; statistics on criminal investigations and convictions in Russia between 1990 and 1997; and an in-depth study of homicide trial records in the Udmurt Republic in 1989-1991 and 1998.Deaths from homicide increased between 1970 and 1985, falling slightly during the 1985 anti-alcohol campaign and then resuming their increase until 1994. Another fall in the late 1990 s was arrested in 1998, with an increase in 1999. By 1999 the age standardised homicide death rate in Russia was 81% higher than in 1990, an increase almost twice that of all causes of death combined. Throughout the 1990 s about 10% of those convicted of homicide were female. Of those homicides leading to convictions in the Udmurt Republic, 71% of those killed by males were male, as were 76% of those killed by females. Killings of women by men often involved sexual assaults. In Russia as a whole, about 80% of those convicted of homicide were reported to be under the influence of alcohol at the time. In the Udmurt Republic, where data on both offender and victim were available, victims were also commonly intoxicated.The nature of homicide in Russia has changed considerably in less than a decade, with many more now involving aggravating circumstances, such as murder to conceal another crime, in association with robbery or rape, or by a group of people. Although still a small proportion of the total convicted, the number of murders by hired killers is also on the rise.The characteristics of those convicted of homicide have also changed during the 1990 s. They are now younger, less likely to have previous convictions, and to have a more diverse range of educational levels. The previous urban-rural gap, with higher levels in rural areas, has also narrowed.     

Tardy posterolateral rotatory instability of the elbow due to cubitus varus

BACKGROUND: Cubitus varus has long been considered merely a cosmetic deformity. The purpose of this paper is to demonstrate a causal relationship between cubitus varus and instability of the elbow. METHODS: In twenty-four patients (twenty-five limbs) with a cubitus varus deformity following a pediatric distal humeral fracture or resulting from a congenital anomaly (three limbs of two patients), tardy posterolateral rotatory instability of the elbow developed approximately two to three decades after the deformity occurred. All patients presented with lateral elbow pain and recurrent instability. The average varus deformity was 15 degrees (range, 0 degrees to 35 degrees ). Surgery was performed in twenty-one patients (twenty-two limbs). Treatment consisted of reconstruction of the lateral collateral ligament and osteotomy in seven limbs, ligament reconstruction alone in ten, osteotomy alone in four, and total elbow arthroplasty in one. RESULTS: In three patients, the triceps muscle was dynamically stimulated intraoperatively to contract while resisting extension of the elbow. This produced posterolateral rotatory subluxation of the elbow, which was reversed by corrective osteotomy and lateral transposition of a portion of the medial head of the triceps that originally had been attached to the elongated, deformed medial aspect of the olecranon. At an average of three years (minimum, one year) after the operation, the result was good or excellent for nineteen of the twenty-two limbs that had undergone an operation; three limbs had persistent instability. CONCLUSIONS: With cubitus varus, the mechanical axis, the olecranon, and the triceps line of pull are all displaced medially. The repetitive external rotation torque on the ulna permitted by these deformities can stretch the lateral collateral ligament complex and lead to posterolateral rotatory instability. Thus, cubitus varus deformity secondary to supracondylar malunion or congenital deformity of the distal part of the humerus may not always be a benign condition and may have important long-term clinical implications. Operative correction can relieve symptoms of instability. The indications for preventive corrective osteotomy remain to be determined.     

Outcome of foot injuries in multiply injured patients

In the past, foot injuries in patients with multiple trauma were thought to be of lesser importance than fractures of long bones. In one prospective study from the authors' institutions, however, multiple-trauma patients with foot injuries were shown to have a poorer functional outcome compared with matched controls. To address these concerns, this article has two parts. The first part is an overview of general principles in the treatment of foot injuries in polytrauma patients. The treatment of specific injuries is beyond the scope of this article, but an approach is highlighted that can be remembered when decisions are made regarding these severely injured patients. The second part reviews the findings from the authors' study, focusing on functional outcomes of multiple-trauma patients with foot injuries.     

Lipid-rich diffuse malignant mesothelioma: a case report

An 80-year old man presented with shortness of breath and was found to have a large right pleural effusion. Cytology of the pleural fluid showed atypical papillary clusters of epithelioid cells. Multiple white-yellow nodules studding the pleural surfaces were seen at thoracoscopy, and biopsies showed solid and papillary clusters of large epithelioid cells with abundant cytoplasm filled with clear vacuoles. Special stains and electron microscopic findings indicated that the tumor was a diffuse malignant mesothelioma with numerous intracytoplasmic lipid vacuoles. Fat stain may be useful at time of frozen section for a pleural-based tumor with vacuolated cells, and the presence of lipid vacuoles in a pleural-based tumor does not exclude diffuse malignant mesothelioma.