Response of human retinal blood flow to light and dark.

The laser Doppler technique was used to measure alterations in retinal blood flow in human subjects under dark-adapted conditions compared to light-adapted conditions. Retinal blood flow increased 40 to 70% after the transition from light to dark. We show quantitatively that the measured increases in retinal blood flow provide the appropriate increases of available oxygen for the inner retinal tissue necessary to compensate for increased oxygen consumption in the dark by the photoreceptor-RPE complex. In addition, we show that measured increases or decreases in human retinal blood flow are quantitatively linked to two intrinsic characteristics of the rod photoreceptor: its metabolic response to known, graded light levels, and its rhodopsin-mediated wavelength-dependent light-absorption properties. We also discuss how light-activated blood flow changes may provide a physiologic test for the autoregulatory capacity of the retinal vasculature.

Acquired cerebral dyschromatopsia.

Color blindness developed in five patients apparently because of lesions in the posterior portions of both cerebral hemispheres. Three of them also had symptoms of prosopagnosia. The lesions were neoplastic in two and vascular in three of the patients. It would appear that bilateral, inferior, occipital lobe lesions may be responsible both for acquired cerebral dyschromatopsia and prosopagnosia. Evidence from experimental investigations in primates suggests that the areas of the cerebral hemispheres analogous to those involved in these patients, may be specialized for the processing of colored stimuli.

Ischemic optic neuropathy in chronic papilledema.

We evaluated the condition of a patient with chronic papilledema due to pseudotumor cerebri in whom a permanent, monocular, inferior, altitudinal, visual field defect suddenly developed. Clinical and fluorescein angiographic findings indicated that the loss of visual field was due to ischemic optic neuropathy. Ischemic optic neuropathy might occur in papilledema if the tissue pressure in the optic disc becomes sufficiently elevated to occlude the pressure-sensitive prelaminar arterioles.

Clinical application of the laser Doppler technique for retinal blood flow studies.

The newly developed laser Doppler technique was used to measure retinal blood flow characteristics in patients with forms of central retinal venous occlusive disease. The measurements were consistent with the expected reduced retinal blood flow in these disease processes.

The mechanism of the clonidine-induced reduction in peripheral parasympathetic submaxillary salivation.

The mechanism of the clonidine induced reduction in submaxillary salivation evoked by electrical stimulation of the chorda tympani was investigated in anaesthetised cats. This effect of clonidine was found to be dose and frequency dependent. In addition to clonidine, tramazoline, also a preferential presynaptic alpha-adrenoceptor agonist, produced a reduction in electricallly evoked salivation. Methoxamine, noradrenaline and naphazoline, which are less potent presynaptic alpha-receptor agonists, caused increases in salivation. Phentolamine only partially antagonized the decrease in salivation produced by clonidine whereas it was virtually abolished by yohimbine. Clonidine increased salivation evoked by intra-arterial injections of carbachol. These findings suggest that clonidine reduces peripheral parasympathetically evoked submaxillary salivation by activation of presynaptic alpha-adrenoceptors which inhibit cholinergic transmission.

The effect of clonidine on centrally and peripherally evoked submaxillary salivation.

In anaesthetised cats, clonidine (10 microgram/kg, i.v.) produced a 60% reduction in submaxillary salivation induced by brain stem stimulation at 10 and 15 Hz and reductions of 35 and 15% in salivation evoked by chorda tympani nerve stimulation at 5 and 15 Hz respectively. Pretreatment with clonidine (20 microgram/kg/day, orally) for 28 days reduced peripherally evoked salivation by 45%. These results suggest that both central and peripheral mechanisms are involved in the diminished salivation produced by clonidine, and the reduction on peripheral stimulation may reflect the presence of presynaptic alpha-adrenoceptors inhibiting cholinergic transmission.

Retinal circulatory changes after scleral buckling procedures.

The noninvasive laser Doppler technique was used to study retinal circulatory characteristics in five patients who underwent uncomplicated scleral buckling procedures. In each patient, the systolic/diastolic variation of the red blood cell speed in the retinal arteries (flow pulsatility ratio) was lower in the eye that had received an intrascleral implant and an encircling band than in the fellow eye. In one patient, an increase in flow pulsatility ratio accompanied an increase in retinal blood flow after removal of the scleral buckling elements. In another patient, the flow pulsatility ratio in the eye that had received a solid implant and an encircling band was less than the ratio in the fellow eye that had received an absorbable implant alone. Our results indicated that reduced retinal blood flow may be common after scleral buckling procedures, and may be a significant factor in otherwise inexplicable postoperative complications.

Postanginal septicaemia (Lemmiere's disease) complicated by haemophagocytosis.

We report a case of postanginal septicaemia complicated by bronchopneumonia and haemophagocytosis in a 19-year old male, presenting with severe thrombocytopenia. We believe that this is the first reported case of thrombocytopenia due to haemophagocytosis in this unusual condition.

Hepatitis C seroprevalence in bone marrow transplant recipients and haemophiliacs.

AIM: To determine the prevalence of antibodies to hepatitis C (anti-HCV) in patients who have undergone bone marrow transplantation in Wellington, prior to the introduction of hepatitis C screening, and to contrast these results with the prevalence of anti-HCV in the Wellington haemophiliac population. METHOD: Serum specimens were obtained from 30 patients who had undergone bone marrow transplantation for the treatment of haematological disorders, and from 29 haemophiliacs. Specimens were analysed using a second generation HCV immunoassay. RESULTS: Exposure to blood products was high in bone marrow transplant recipients with subjects receiving red cells or platelets from an average of 53 donors (range 15-100, SD 23.2) during their transplant procedure. Despite the high usage of blood products, only one of the 30 patients tested was positive for hepatitis C on the basis of second-generation antibody testing. Confirmatory testing in this patient, (anti-HCV immunoblot assay) was negative. In contrast, 26 of 29 (89%) haemophiliac patients tested were positive for anti-HCV. CONCLUSION: Although the infective risk of blood products cannot be underestimated, the risk of patients contracting hepatitis C from multiple single-unit transfusions, prior to the introduction of screening for hepatitis C was low. This contrasts with the high risk of hepatitis C seroconversion in patients exposed to pooled plasma products.

Treatment of hairy cell leukaemia with recombinant alpha interferon.

Eleven patients with progressive hairy cell leukaemia (three nonsplenectomised) were treated with recombinant alpha-2 interferon (Intron-A or Roferon-A) subcutaneously three times per week at a dosage of 3 x 10(6) units. Ten patients completed at least ten weeks of therapy and could be evaluated; one patient died of haemorrhage from severe thrombocytopenia after only three weeks treatment. Nine of the ten patients responded and all of these are regarded as good partial remissions (normalisation of all blood parameters but still discernible hairy cells in the marrow). Responding patients have all been followed for a median of two years and in one case 3 1/2 years since commencement of therapy. The patients are all transfusion independent and free of infection. We conclude that alpha-2 interferon therapy for progressive hairy cell leukaemia is effective therapy in both splenectomised and nonsplenectomised patients.

Relationships between role models and role perceptions of new graduate nurses.

This study was conducted to examine relationships between role models and role perceptions of new graduate nurses. The sample consisted of the 25 senior nursing students in a generic baccalaureate nursing program who were administered questionnaires 1 month prior to graduation and 3 months after beginning employment. Results indicated that: (a) a majority of faculty role models of new graduate nurses are replaced by work-related role models in the first 3 months of employment, (b) the most important role model characteristic was clinical experience/performance, and (c) role perception orientations of new graduate nurses are overwhelmingly professional prior to graduation, but become more bureaucratic after exposure to work-related models. This study validates the findings of similar research conducted over the past 25 years. Further research is needed into factors that lead to the perpetuation of a bureaucratic work environment and bureaucratic nurses, in spite of professionally oriented nursing education.

Permanent pacemakers in nonagenarians.

We report our experience of 20 patients who have had permanent pacemakers implanted for the first time after the age of 90. The main indications were syncope or presyncope which occurred in 15 patients. Complete heart block was present in 14 patients. Syncopal and presyncopal symptoms were cured in 73%. Nonagenarians paced for complete heart block can expect to survive for as long as others of the same age without heart block. Permanent pacing is an effective and appropriate treatment in the very old.

Identifying potential family practice social work opportunities.

The results of a survey of private primary care family physicians relative to their interest in having social workers associated with their practices are reported. There are several family physician and practice setting variables associated with a positive response to the question of whether family physicians have or would like to have a social worker associated with their practice. These findings should be beneficial to social workers interested in becoming established in family practice. Implications of these factors are discussed.

Abnormal diastolic movement of the interventricular septum caused by a prolapsing right atrial myxoma.

A 40 year old woman with cough and exertional dyspnoea was found to have a large right atrial myxoma by M mode and cross sectional echocardiography. Prolapse of the tumour into the right ventricle occurred during diastole with sufficient force to cause mechanical distortion of the interventricular septum. Septal motion became normal after surgical resection of the myxoma.