An alternative design of extension prosthesis

Some patients with a congenitally shortened lower limb can be fitted with a total contact socket of one piece construction, dispensing with the need for removable panels or split socket construction. This gives advantages in weight, strength and cosmesis. The technique is described and compared with those conventionally used.     

Hip pain in adolescence

No single pelvic or femoral osteotomy can be expected to correct the range of deformity encountered in the adolescent with a subluxed hip or the sequelae of treatment at a younger age. A range of pelvic and femoral osteotomies on both sides of the joint are required when there is marked deformity. The principles of management of the anatomic derangement of the painful adolescent hip are different from those in the younger child. Anatomic and biomechanical restoration at skeletal maturity must be perfect for the hip to function well in the long term. The plasticity and capacity for remodeling is much less than in the child. Postoperative immobilization must be avoided if joint stiffness is to be avoided. While the results of arthroplasty are the standard to which osteotomy must be compared, the high failure rate in young adults and pessimistic prospects of revision make biologic alternatives more attractive. The success of osteotomy depends on correct indications, careful preoperative planning, precise technique, rigid fixation, and early postoperative movement. When the indications for osteotomy cannot be met, arthrodesis is still the best solution for unilateral hip disease in patients younger than 30 years of age of either sex.     

Caffeine and the benign encephalopathy of pregnancy

D. W. Barnes, D. A. Sirbasku & G. H. Sato, (eds.): Cell culture methods for molecular and cell biology. P. M. Gootman (ed.): Developmental neurobiology of the autonomic nervous system. M. Sandler, C. Feuerstein, B. Scatton (eds.): Neurotransmitter interactions in the basal ganglia. Harry M. Zimmerman (ed). Progress in neuropathology. M. Yahr & K. J. Bergmann (eds.): Parkinson's disease. G. Bock & M. O'Connor (eds.): Selective neuronal death. H. Julia Hannay (ed.): Experimental techniques in human neuropsychology. D. Papakostopoulos, S. Butler, I. Martin (eds.): Clinical and experimental neuropsychophysiology J. C. Rothwell: Control of human voluntary movement.     

Biology of aging. Current state of knowledge

The nature of the primary aging processes has yet to be defined. Mortality and aspects of longevity (eg, life expectancy) do not provide significant information about aging. The maximum life span potential of a species does provide information about the comparative rate of aging between species, however, and also is a good marker for evaluating interventions aimed at modulating the rate of aging in a particular species. Physiological deterioration occurs with age, but it is not known how much is due to aging per se and how much is secondary to age-related disease and life-style. There are similar reservations about the changes in body composition that have been noted with increasing age. Many diseases are age related in terms of prevalence, but how these diseases relate to the primary aging processes remains to be defined. Finally, many claims have been made concerning interventions that will retard the aging processes; of these, only food restriction in rodents has been unequivocally shown to retard the aging processes of a mammalian species.     

In vivo electrochemical demonstration of potassium-evoked monoamine release from rat cerebellum

In vivo electrochemical methods were employed to study the potassium (K⁺-evoked release of monoamines from the cerebellum of the chloral hydrate anesthetized rat. K⁺-evoked releases were elicited using micropipette-Nafion-coated graphite epoxy electrode arrays in the granule/Purkenje cell layer, molecular layer, and white matter. These recorded releases were generally found to be reversible, moderately dose-dependent, and reproducible. However, the temporal dynamics of the releases were different for the cell layer versus molecular layer records. Releases were infrequently observed in cerebellar white matter, an area which is relatively devoid of monoamine containing terminals. The signals recorded from the cell and molecular layers were significantly attenuated by pretreatment with nomifensine, a potent catecholamine reuptake blocker, significantly prolonged the K⁺-evoked signals observed in both the granule/Purkenje cell and molecular layers. These data, taken together with earlier reports on the electrophysiological responses to activation of cerebellar noradrenergic inputs, support the conjecture that in vivo electrochemical recording methods have the sensitivity and spatial resolution for studies of functional monoamine release from brain regions that have a diffuse or laminated monoamine innervation.     

Binocular contrast detection with unequal monocular illuminance

Binocular summation was measured in eight normal subjects by means of psychometric functions for contrast detection. An average 47% increase in binocular over monocular performance was obtained. Our data agreed with the simple summation model of Signal Detection Theory (Legge, 1984). Binocular psychometric functions were also measured when the sensitivity of one eye was decreased by means of a 1.0 neutral density (ND) filter. We found that binocular detectability in this case was reduced to below that of the better eye. This binocular inhibition was seen in all subjects. The slope of a contrast detection function gives a measure of the rate of change in detectability with contrast. If the slopes of two functions are equal, then the difference in detectability between these functions remains constant for all the contrast values used. When the slopes of the measured functions were analysed, no significant differences were found under any of the testing conditions. This indicates that the magnitude of summation (with equal monocular sensitivities), and of inhibition (with unequal monocular sensitivities), remains constant across the range of stimulus contrasts. The clinical implications of binocular inhibition are discussed.     

A Leydig cell stimulatory factor produced by human testicular tubules

It is demonstrated that tubular fragments derived from human testes and cultured in vitro produce a factor that stimulates the production of testosterone by human interstitial cells and by Percoll-purified Leydig cells from rat and mouse origin. The active principle in the conditioned media is a thermo-labile and trypsin-sensitive protein with an MW greater than 10,000. The factor is active in the presence as well as in the absence of maximally effective concentrations of LH and its activity is not accompanied by measurable changes in cAMP production. There are several points of analogy between this factor and a Leydig cell stimulatory protein produced by rat Sertoli cells. Molecular weight fractionation of spent media from human testicular tubules using an Amicon ultrafiltration system results in a 38- to 102-fold increase in Leydig cell stimulatory activity in a fraction corresponding to a molecular weight of 10,000 up to 30,000. These figures are comparable to those observed after molecular weight fractionation of spent media from rat Sertoli cells. Dose-response curves with partially purified preparations from human and rat origin yield parallel dose-response curves. In rat Sertoli cells as well as in human testicular tubules, the production of the active principle is stimulated by FSH and dibutyryl cAMP. Finally, maximally effective concentrations of the active principles of human and rat origin display no additive effects whereas additive effects are clearly evident with other Leydig cell stimulatory factors such as LHRHa and EGF. The hypothesis is advanced that the Leydig cell stimulatory factors from tubular origin may act as paracrine regulatory molecules responsible for the effects of FSH on Leydig cell function.     

Radiotherapy in the management of pancreatic islet cell tumors

Malignant islet cell tumors are commonly treated with surgical resection. Chemotherapy is reserved for residual, unresectable, or metastatic disease. The role for radiotherapy has not been clearly defined. This article describes three cases of advanced islet cell tumors treated effectively with radiotherapy. This experience, in addition to that from other published reports, suggests that radiotherapy is a useful mode for treating advanced islet cell carcinoma.