How older people in the United States and Germany fared in the growth years of the 1980s: a cross-sectional versus a longitudinal view.

OBJECTIVES: The goal of the study was to show that cross-sectional and longitudinal data yield dramatically different answers to a basic question: "How did older persons fare in the recovery years of the 1980s?" METHODS: The United States Panel Study of Income Dynamics and the German Socio-Economic Panel are used cross-sectionally to capture changes in the economic well-being of older persons in the trough and peak years of the 1980s business cycle, and longitudinally to trace how the economic well-being of a given cohort of older persons changed over those years. Kernel density estimation is then used to show how the distribution of economic well-being of these populations changed over these years. RESULTS: Cross-sectional comparisons confirm that persons aged 65 and over in the peak year were better off than persons aged 65 and over in the trough year in both countries. Longitudinal comparisons, however, show that persons aged 65 and over in the trough year who survived to the peak year received a substantially smaller share of the rewards of economic recovery than cross-sectional comparisons imply. Moreover, the entire income distribution of older persons in the United States shifted downwards. DISCUSSION: Compositional changes in the cross-sectional data, caused by the entry of high-income persons who are young in the peak year but old in the trough year, obscure the decline in the economic well-being of the cohort of older persons who survived the trough year, in cross-sectional comparisons of older populations in the United States in the 1980s.

A study of the dimensions and taper angles of the medullary canals of the proximal and middle phalanges.

The morphology and dimensions of the medullary canals of the proximal and middle phalanges have been studied with particular interest shown to the angle of taper of these canals. Measurements of 50 cadaveric fingers were taken from computer aided tomographic images using AutoCAD software. Tangents were fitted to the inner cortices in two orthogonal planes and the angles between them were measured. The angles of canal taper in the proximal phalanx were remarkably similar for each digit. This was also true for the middle phalanx of the index, middle and ring fingers but the taper of the middle phalanx of the little finger was found to be different.

Deficits of [3H]D-aspartate binding to glutamate uptake sites in striatal and accumbens tissue in patients with schizophrenia.

The hypothesis involving glutamate in the neuropathology of schizophrenia has attracted great interest. Several studies report dysfunctions in glutamatergic systems, including alterations in kainate and N-methyl-D-aspartate (NMDA) receptors in various areas, as well as changes in the number of glutamate uptake sites. We have studied this further using [3H]D-aspartate binding to glutamate uptake sites as a measure of the integrity of presynaptic glutamate systems in several areas (caudate nucleus, putamen, nucleus accumbens, frontal cortex and temporal cortex) of brain tissue taken at autopsy from schizophrenic patients and controls. A significant decrease in the number of glutamate uptake sites was apparent in caudate nucleus, putamen and nucleus accumbens in the schizophrenia group, indicating an impaired glutamatergic innervation of these subcortical regions. However, no significant changes were found in the two cortical regions studied.

Prevalence of knee problems in the population aged 55 years and over: identifying the need for knee arthroplasty.

OBJECTIVE: To determine the prevalence of knee problems in people aged 55 years and over and identify those who should be considered for knee arthroplasty. DESIGN: Postal survey; questionnaires were sent to a multistage stratified probability sample of residents of North Yorkshire Health Authority aged 55 and over. SETTING: A health district with a population of 210,000 aged 55 and over. RESULTS: An initial four page postal questionnaire produced an 86% response rate among 18,827 eligible patients. A subsequent detailed questionnaire sent to 1277 patients with knee problems (with a response rate of 78%) then determined the prevalence of severe pain and severe disability. Pain and disability consistent with the need to consider arthroplasty was found in 20.4/1000 (95% confidence interval 18.0 to 23.1); of these, 4.1 (2.7 to 5.8)/1000 had extreme disability. Age and sex specific rates in men who might benefit from arthroplasty were, in those aged 55-64, 12.9 (8.4 to 19.0)/1000; aged 65-74, 12.1 (7.4 to 18.4)/1000; aged 75 and over, 20.3 (12.9 to 30.5)/1000. In women aged 55-64 the rates were 12.9 (8.6 to 18.7)/1000; aged 65-74, 19.6 (13.9 to 26.7)/1000; aged 75 years and over, 42.6 (34.3 to 52.4)/1000. CONCLUSIONS: Total knee replacement has until recently been considered unreliable and often seen as a last resort for many with severe knee problems. Advances in prosthesis design and surgical and anaesthetic techniques have transformed this procedure into a reliable option with a potential for reducing disability and dependency in a large number of people in the community. Understandably, the prevalence pool of those who may benefit is large; health authorities and, increasingly, general practitioners should consider purchasing more total knee replacement surgery to offer real choice to those in need.

Grip strength and endurance in rock climbers.

The performance of competition climbers in laboratory-based tests of pinch and whole hand grip strength and endurance was compared to that of non-climbers of the same age, sex and physique. Climbers performed significantly better, indicating higher stresses acting in the flexor mechanism, possibly predisposing injury. Attempts were made to correlate the performance in the tests to climbing achievement, measured by current technical climbing standards. Although pinch grip strength increased with the length of climbing experience, there was no evidence that strength in the hands alone guarantees success in competition climbing.

D-aspartate binding to the glutamate uptake site in human brain tissue--effects of leucotomy.

Binding of [3H]D-aspartate, as an indicator of glutamate uptake sites, was investigated in post-mortem human brain tissue by use of a centrifugation assay to separate free and bound ligand. Binding was displaceable, apparently saturable and to a single site, with mean KD and Bmax values of 2.3 microM and 40.3 nmol/g tissue in the frontal cortex. The method was applied to the study of tissue from frontal and temporal cortices and the caudate nucleus of five psychiatric patients who had undergone a frontal leucotomy. The effects of this neurosurgical procedure were to diminish by almost 50% the density of D-aspartate binding sites in the frontal cortex and caudate nucleus, while the temporal cortex was less affected. It is concluded that the method provides a potentially useful correlate of glutamatergic innervation in human brain tissue.

Validity of cadaveric data for muscle physiological cross-sectional area ratios: a comparative study of cadaveric and in-vivo data in human thigh muscles.

Muscle physiological cross-sectional area (PCSA) is calculated from muscle volume, fibre length and fibre pennation angle, and is a measure of force/stress. Muscle force analyses in the human body usually yield combined forces of groups of synergistic muscles rather than individual muscle forces, because of the constraints of statically determinate models. As stresses acting in a group of muscles are uniform, the ratio of the physiological cross-sectional areas of a group of muscles can be used to divide the combined force into its component parts. This paper investigates the validity of the common practice of using cadaveric physiological cross-sectional area to divide in-vivo group muscle forces into component parts. Muscle volumes were determined in vivo using a combination of radiographic techniques for a small number of active young males, and 'in-vivo' physiological cross-sectional areas were calculated using cadaveric data for fibre length and pennation angle. As would be expected, in absolute terms, the 'in-vivo' values were much larger than those of cadavers. Comparison of the percentage contribution of each muscle to the total value of its group showed little difference between the cadaveric and 'in-vivo' data. We conclude that it is reasonable to use cadaveric data when only relative physiological cross-sectional areas are required, more so in the quadriceps than in the hamstrings. Considering data from active young subjects and cadavers, we have shown the ratios of the physiological cross-sectional area of the individual muscles of the quadriceps (and to a lesser extent the hamstrings) to be comparable. This validates the practice of using cadaveric data for relative physiological cross-sectional area in statically determinate force analysis in the human body. 9n-vivo' ratios are also presented for future use.

Ratios of cross-sectional areas of muscles and their tendons in a healthy human forearm.

The muscles and tendons in the forearm and hand of a young man, amputated after an accident, have been weighed and measured. The physiological cross-sectional areas of those muscles that had long tendons were 35 +/- 9 (mean and standard deviation) times the cross-sectional areas of the tendons. The mean is very close to the optimum calculated from the theory of Ker, Alexander & Bennett (1988). It implies that the tendons experience stresses of about 11 MPa and strains of about 1.3%, when the muscles exert their maximum isometric forces. Very much larger forces would be needed to break the tendons.

Sarcomere length changes in muscles of the human thigh during walking.

In a previous investigation (Cutts, 1988a) sarcomere lengths were determined for muscles of the thigh in the anatomical position, and a method devised for the prediction of sarcomere lengths at other positions. In the present investigation, this information was used to predict the sarcomere length changes in the muscles of the thigh during walking, in conjunction with ciné film and bone models of experimental subjects. When compared with the length tension curve for human muscle (Walker & Schrodt, 1973), the results indicate that during walking the muscles operate at sarcomere lengths near the plateau of the curve, where maximum tension can be realised.

Shrinkage of muscle fibres during the fixation of cadaveric tissue.

It has been shown that a small but significant loss in length occurs in human muscles which are fixed after removal from the skeleton. A comparison was made between the loss in muscle length when muscles were fixed in isolation from, and whilst still attached to, the skeleton in the rat. The conclusion was that no significant loss of length occurs when the muscles were fixed intact on the skeleton. Since the length loss when muscles are fixed independently of the skeleton in both the rat and the human is of the same order, it is reasonable to assume that when human muscles are fixed on the skeleton, no significant loss in length occurs. Since all human cadaveric tissue is fixed whilst on the skeleton, we may assume that shrinkage of the muscles in such specimens is negligible.

The range of sarcomere lengths in the muscles of the human lower limb.

The lengths of the sarcomeres of some muscles of the human leg were determined for the anatomical position, using a method based on diffraction. Measurements were made of the muscle lengths and angles of pennation from cadavers, and these were used to predict sarcomere lengths at other limb positions. The measured and predicted sarcomere lengths were compared with the length-tension curve for human muscle, which showed the range of sarcomere length from both extremes of muscle length to cover the entire range of the length-tension curve.