Postural changes in perfusion pressure and retinal arteriolar calibre.

Ophthalmic artery perfusion pressures and retinal arteriolar calibres were studied in 10 human subjects when sitting, standing, and lying. Differing responses in perfusion pressure were found; autoregulatory responses were found in 13 of the 18 significant calibre changes on moving from sitting to standing and 13 of 22 significant calibre changes on moving from standing to lying. The remaining significant calibre changes were non-autoregulatory, the arterioles dilating with perfusion pressure increase and constricting with decrease.     

Some characteristics of verbal behaviour in presenile dementia.

Two experiments concerned with the statistical characteristics of speech in presenile dementia are described. Apart from a lowered rate of production of words under certain conditions no speech abnormalities were detected on the variables examined.     

Primary care. Who's sorry now?

Almost two-thirds of health authorities believe their relationships with GPs have improved since the merger. Forty-four percent of LMCs think there has been no change, and 42 per cent report a deterioration. More than half the LMCs believe knowledge and understanding of GPs' contracts, and payments, have declined since the merger.     

A bibliography of drug discrimination research, 1992-1994

The major content of this publication is a comprehensive bibliography of research into the discriminative stimulus effects of drugs in animal and human subjects for the period 1991-1994. The bibliography is accompanied by a detailed cross-index that facilitates access to this literature through keywords based on the drugs studied, how the drugs were used, and numerous other methodological variables such as species of subject and schedule of reinforcement. The article also explains how users may obtain access to the present and earlier versions of the database, which are available as computer disks and over the Internet. The easy access to this literature made possible by the database should increase the working efficiency of the many groups that employ drug discrimination methods and should also support dissemination of the knowledge acquired to a wider scientific community.     

Risk factors for thrombosis in pregnancy

Pregnancy is a hypercoagulable state affecting both the coagulation and the fibrinolytic systems. Any exacerbation of the pre-disposing factors for coagulation may well lead to a thrombotic event more often in pregnant women than in the general population. Arterial thrombosis is very rare in pregnancy. Pre-eclampsia may be a risk factor for the development of arterial disease in later life. Venous thromboembolism (VTE) in pregnancy, although still rare, is a major cause of maternal mortality. Risk factors, such as older age, increased weight and emergency Caesarean section, as well as acquired and genetic thrombophilia, often coexist and reinforce each other. Appropriate thromboprophylaxis needs to be considered and applied on an individual basis. Uteroplacental thrombosis provides a common pathophysiological link between various poor pregnancy outcomes, including recurrent miscarriage, stillbirth, placental abruption, fetal growth restriction and pre-eclampsia. Its significance depends on the gestational age. Acquired and genetic thrombophilia may be associated with such conditions, particularly in early-onset disease. More data are required to assess the significance of such thrombophilias in obstetric practice. Any treatment should be in the context of clinical trials.     

Olfactory receptor surface expression is driven by association with the beta2-adrenergic receptor

Olfactory receptors (ORs) comprise more than half of the large class I G protein-coupled receptor (GPCR) superfamily. Although cloned over a decade ago, little is known about their properties because wild-type ORs do not efficiently reach the cell surface following heterologous expression. Receptor-receptor interactions strongly influence surface trafficking of other GPCRs, and we examined whether a similar mechanism might be involved in OR surface expression. Olfactory neurons are known to express beta-adrenergic receptors (ARs), and we found that coexpression with beta(2)-ARs, but not any other AR subtypes, dramatically increased mouse 71 (M71) OR surface expression in human embryonic kidney 293 cells. A persistent physical interaction between M71 ORs and beta(2)-ARs was shown by coimmunoprecipitation and by cointernalization of the two receptors in response to their specific ligands. Also, coexpression of wild-type M71 ORs with beta(2)-ARs resulted in cAMP responses to the M71 ligand acetophenone. Finally, in situ hybridization studies showed extensive colocalization of M71 OR and beta(2)-AR expression in mouse olfactory epithelium. These data demonstrate the successful heterologous surface expression of a functional wild-type OR and reveal that persistent physical association with other GPCRs can control OR surface expression.