Utility of the PFA-100 as a screening test of platelet function: an audit of haemostasis laboratories in Australia and New Zealand.

The PFA-100 is a relatively new laboratory instrument, first described in 1995. There have since been numerous studies assessing its utility as a screening tool for platelet dysfunction and/or von Willebrand's disease (VWD). The PFA-100 displays variable sensitivity to different types of platelet disorders, as well as to antiplatelet medication (e.g. aspirin), with similar caveats for monitoring of primary haemostasis-promoting therapies in platelet dysfunction. There is therefore considerable uncertainty regarding its utility within this context, and we have accordingly performed an audit of usage among participants of the Royal College of Pathologists of Australasia Quality Assurance Program. Of 105 laboratories surveyed, 40 responded that they performed platelet function testing, with 26 (65%) further indicating they utilized the PFA-100. We report a wide variety of laboratory usage among these users, including numbers of tests performed [annual median (range) = 270 (15-6000)], sources of requests (clinical sources and localities), testing criteria and follow-up action. Most tests were completed within 4 h of collection, as recommended by the manufacturer, and most tests were performed as a replacement, or as a preliminary screen of platelet function (i.e. classical aggregation). Most abnormal findings, however, were attributed to antiplatelet medication such as aspirin.     

Social workers and their clients: a comparison between primary health care and local authority settings

A social work attachment scheme to several general practitioners was established. Data from the first 300 referrals to the scheme were compared with data from a previous study of referrals to the `intake' teams of the social services department of the same London borough. In addition, data about the activities of the social workers in the `attachment' were collected, and the work was found to be predominantly short-term.

The populations referred to social workers in both settings were found to be similar in age and sex. Although general practitioners in the area referred only a few clients to social services departments, the clients in both groups were generally in poor health.

The psychiatric morbidity of those referred to the attached social workers was significantly higher, however, than those referred to the intake team (p < 0·01), and their problems were also more likely to need psychological help rather than practical measures. These differences were considered to be due mostly to the different types of referral agencies operating in the two settings and to their perceptions of the social worker's role.

The findings support the argument for closer liaison between medical and social services in the community: the attachment of social workers to general practices proved to be particularly valuable in the management and treatment of patients with emotional and mental illness.

     

Intracellular calcium modulates gallbladder ion transport

Although experimentally induced cholesterol gallstone formation has been associated with altered gallbladder (GB) absorption and increased biliary Ca2+, the relationship between these events remains unclear. Recent studies suggest that extracellular Ca2+ ([Ca2+]ec) influences GB ion transport. Whether the effects of [Ca2+]ec are mediated by changes in intracellular Ca2+ ([Ca2+]ic) has not been determined. This study was designed to define the effects of altered [Ca2+]ic on GB ion transport. Prairie dog GBs were mounted in a Ussing chamber and short-circuit current (Isc), potential difference (Vms), and resistance (Rt) were recorded. Mucosal surfaces were exposed to either Dantrolene (Dt) or nickel (Ni2+). Dt "traps" [Ca2+]ic within intracellular organelles, thereby lowering cytosolic Ca2+; and Ni2+ prevents influx of [Ca2+]ec, presumably by binding Ca2+ channels. Although Dt reduced both Isc and Vms (P less than 0.01), these effects were transient. Transport recovery was probably due to increased [Ca2+]ec influx with restoration of [Ca2+]ic. Ni2+ resulted in sustained decreases in Isc and Vms (P less than 0.05) despite subsequent addition of 10 mM Ca2+. These findings are consistent with the prevention of [Ca2+]ec influx by Ni2+. We conclude that: (1) [Ca2+]ic may be a modulator of GB ion transport and (2) previously reported [Ca2+]ec effects on ion transport may be mediated through [Ca2+]ic concentration changes.