Shared care: a review of the literature

This review examines broad issues of concern regarding the primary/secondarycare interface. The main purpose was to identify areas of goodpractice which could be adapted for more general use. One ofthe most fundamental aspects identified was communication, whichis discussed in some detail. Also covered are shared prescribingand disease management. The data suggest that the most effectivesystem(s) of shared care has yet to be established. Furtherqualitative and economic evaluations are required, taking intoaccount patient preferences. Although the literature does describecertain practice exemplars, it is clear that inter- and intra-professionalcommunication continues to be a problem. Whilst informationtechnology may provide some of the solutions, it is concludedthat a culture change, which compels health professionals tomake sharing of patient information a much higher priority,is reauired. Keywords. Shared care, seamless care, hospital, general practice, family practice.     

Expression of type-X collagen in osteoarthritis

The present study was undertaken to examine how osteoarthritis affects the expression of type-X collagen, a hypertrophic chondrocyte-specific collagen in articular cartilage. A well characterized sheep polyclonal antiserum, as well as three mouse monoclonal antibodies against canine type-X collagen, was used to immunolocalize type-X collagen in human and canine joints. Its expression in osteoarthritic cartilage was altered in several locations. In the canine osteoarthritic joints, type-X collagen increased in and just above the zone of calcified cartilage and was present diffusely throughout the calcified matrix. In both the human and canine cartilage, type-X collagen was localized around cell clones in the transitional zone of cartilage. This is surprising, since that region of the cartilage does not calcify and one of the proposed roles of type-X collagen is in mineralization. Thus, the osteoarthritic process may damage the matrix in the superficial layer and induce changes leading to the expression of the hypertrophic chondrocyte phenotype.     

The human locus coeruleus: computer reconstruction of cellular distribution

Quantitative neuroanatomical techniques were developed to map the distribution of norepinephrine-containing locus coeruleus (LC) neurons in the adult human brain. These neurons reside in the dorsolateral pontine tegmentum and are identifiable by their neuromelanin pigment content. Five brains, ranging in age from 60 to 104 years, were examined. Outlines of coronal or sagittal sections containing the LC were entered into a computer along with the location of each cell, certain neuroanatomical landmarks, and cell size. Sections were aligned with specific neuroanatomical landmarks so that the computer-generated distribution of cells was representative of the in situ distribution of cells. Analysis of (1) the number of cells in sections throughout the rostrocaudal extent of the nucleus, (2) cell size, (3) 3-dimensional reconstructions of the distribution of cells within the brain stem, and (4) 2-dimensional cell-frequency maps, make it possible to quantitatively characterize the distribution of cells within this large nucleus. The total estimated number of LC cells on both sides of the brain ranged from 45,562 to 18,940 (youngest to oldest), and mean soma area ranged from 835 to 718 micron 2 (youngest to oldest). The nucleus is "tube-like" in shape, has a rostrocaudal extent of approximately 16 mm, and is bilaterally symmetrical. Two-dimensional cell-frequency maps were developed to illustrate the regional distribution of cell frequencies at any rostrocaudal/mediolateral point on the horizontal plane; the total unilateral area of the LC ranged from 32.8 to 17.2 mm2 (youngest to oldest). The techniques developed to characterize the 2- and 3-dimensional distributions of LC neurons can be used in future studies to quantitatively examine the effects of aging and disease on this and other brain nuclei.     

U.S. lung cancer mortality and declining cigarette tobacco consumption

The usual method for estimating population exposure to cigarette tobacco has been annual per capita consumption of cigarettes, expressed as pack-years or numbers of cigarettes consumed. This technique is shown to result in an inaccurate estimate of exposure. It underestimates by 11 years the latency period from peak exposure to peak mortality. Over the years, cigarettes changed markedly. Filters came into prominence and tobacco was "fluffed". On average, tobacco content of cigarettes decreased 39.1% from 1953 to 1981. National per capita consumption of cigarette tobacco declined by 43%. Total exposure to cigarette tobacco has been declining for males for approximately 35 years; for females for 20 years. As of 1982, the secular trend for lung cancer mortality was declining for women below age 45 and for most age groups of men below 65. We appear to be at the threshold of a reversal in overall lung cancer mortality.     

The mucosal barrier, IgE-mediated gastrointestinal events, and eosinophilic gastroenteritis.

The "mucosal barrier" plays an important role in regulating immune responses in the gastrointestinal tract. Although the precise mechanisms controlling mucosal immune responses have not been defined, when an abnormal response such as IgE production is initiated, a variety of complex and incompletely understood pathophysiologic events occur and can result in gastrointestinal pathology. This article attempts to present the complexity of such abnormal responses. Although more questions have emerged than were answered, in recent years our knowledge of the pathophysiology of IgE-mediated events in the gastrointestinal tract has advanced significantly. Our understanding of the pathophysiology of these events will ultimately allow the development of more directed and effective therapeutic interventions for allergic gastrointestinal diseases. In addition, through further clinical and basic research, we should begin to unravel the more enigmatic conditions affecting the gastrointestinal tract, such as EG.     

Antiarrhythmic actions of tedisamil: Studies in rats and primates

Tedisamil is a new bradycardic agent, previously shown to block transient outward and delayed rectifier potassium currents in cardiac tissue [1,2]. In the present study tedisamil caused bradycardia and Q-Tc widening in rats and primates. Q-Tc widening is indicative of class III antiarrhythmic actions. In keeping with this, tedisamil had antiarrhythmic activity against electrical and ischemia-induced arrhythmias in rats. In rats, 0.5–4 mg/kg IV tedisamil caused parallel and dose-related increases in action-potential duration, Q-Tc interval, and refractory period; and decreases in maximum ventricular following frequency. In primates after 0.5–2.0 mg/kg IV, findings were similar for indices of Q-T widening and decreases in maximum ventricular following frequency. Tedisamil did not change QRS width, nor did it increase threshold currents for capture of ventricles, nor for fibrillo-flutter at doses below 4 mg/kg in rats. These findings were consistent with the lack of significant sodium-channel blockade. However, upon increasing the dose to 4 mg/kg, ventricular fibrillo-flutter could not be induced in rats by electrical stimulation; instead, only ventricular tachycardias with slow rates occurred. Ischemia-induced ventricular fibrillation was reduced in a dose-related manner by tedisamil in rats. The overall incidence of ischemia-induced ventricular tachycardia was not markedly reduced, but rates during tachycardic episodes were lower. When pacing was used to overcome tedisamil-induced bradycardia, antiarrhythmic actions during ischemia were more pronounced. These findings are consistent with the hypothesis that tedisamil increased refractoriness, which resulted in extended path lengths for reentry circuits and slower rates during episodes of ventricular tachycardia. High doses of tedisamil increased path lengths so much that the multiple reentry circuits of fibrillation could no longer occur. The limited study in primates suggests similar mechanisms could occur in humans.     

"Cross-talk" in recording evoked potentials.

When two potentials having large amplitude differences are simultaneously recorded, the large amplitude potential contaminates the small amplitude response. The small, early potentials generated by this contamination resemble far-field potentials. Although scalp-recorded SEP was contaminated by waves similar to the peripheral potential, peak latencies and wave form were not identical. Experiments simulating the recording situation verified the presence of "cross-talk." Capacitive coupling would shift peaks and alter the wave forms. Other possible mechanisms for the cross-talk and methods of minimizing it are offered. One should be cautious interpreting the results when potentials of large amplitude differences are simultaneously recorded.     

Proteus syndrome

The term Proteus syndrome was coined in 1983 to describe a disorder of skeletal, hamartomatous, and other mesodermal malformations. The syndrome was named after the Greek god Proteus, whose name means "the Polymorphous." Clinical features of this new syndrome are currently being defined. Including the case reported herein, we have found 34 patients with Proteus syndrome described in the English literature. Major clinical findings, defined as those findings seen in more than half of the cases, include hemihypertrophy, macrodactyly, exostoses, epidermal nevi, characteristic cerebriform masses involving the plantar or palmar surfaces, a variety of subcutaneous masses, and scoliosis. Histologic examination of subcutaneous masses has identified a variety of lipomatous, hamartomatous, and angiomatous tumors.     

The controversy over radiation safety. A historical overview

The hazards of ionizing radiation have aroused concern since a short time after the discovery of x-rays and natural radioactivity in the 1890s. Misuse of x-rays and radium prompted efforts to encourage radiation safety and to set limits on exposure, culminating in the first recommended "tolerance doses" in 1934. After World War II, the problems of radiation protection became more complex because of the growing number of people subjected to radiation injury and the creation of radioactive elements that had never existed before the achievement of atomic fission. Judging the hazards of radiation became a matter of spirited controversy. Major public debates over the dangers of radioactive fallout from atmospheric bomb testing in the 1950s and early 1960s and the risks of nuclear power generation in later periods focused attention on the uncertainties about the consequences of exposure to low-level radiation and the difficulties of resolving them.     

Effects of halothane on arrhythmias induced by myocardial ischaemia

The effect of halothane on arrhythmias induced by ischaemia was investigated in rats, isolated perfused rat hearts, and pigs. Responses to the occlusion of the left anterior descending coronary artery were determined in groups (n = 9) of chronically prepared rats treated with no halothane, 0.5, or 1.0 per cent halothane immediately after occlusion; in isolated rat hearts (n = 10) treated with no halothane, 0.5, 1.0, 2.0, or 4.0 per cent halothane for 15 min before and after occlusion; and 20–25 kg pigs (n = 11) anaesthetised with halothane or pentobarbital. The ECG, arrhythmias, blood pressure (BP), heart rate (HR) and extent of infarction were determined in each model. In pigs, left ventricular pressure, dp/dt_max and cardiac output were also measured. In chronically prepared rats, halothane anaesthesia started after occlusion was antiarrhythmic and decreased the incidence of ventricular fibrillation and resulting mortality. In isolated rat hearts, 0.5 or 1.0 per cent halothane had little effect on occlusion-induced arrhythmias. The highest concentration of halothane increased the incidence of ventricular fibrillation both before and after occlusion. Halothane decreased developed ventricular pressure in a dose-dependent manner. In acutely prepared pigs, halothane pre-treatment had no appreciable effect upon occlusion-induced arrhythmias when compared with pentobarbital anaesthesia. Thus, halothane is antiarrhythmic when treatment is initiated after occlusion in the rat but this action is not seen in isolated hearts or intact pigs. The antiarrhythmic action of halothane is, therefore, species and model dependent.