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We have compared the effects of a 48-h continuous infusion of arginine vasopressin (AVP) given to four subjects (one subject studied twice) with that given to four patients lacking adrenocortical function and maintained on fixed doses of mineralocorticoid and glucocorticoid replacement therapy. Both patients and normal subjects were subjected to dietary salt and water restriction during the period of the infusion, and all participants were in balance on a low sodium diet at the start of the infusion period. Infusion of vasopressin in normal subjects was associated with an increase in fractional excretion of sodium by the kidney, which continued during the day after the infusion was stopped. The infusion was also associated with a fall in plasma aldosterone as well as falls in whole blood packed cell volume, plasma renin activity and plasma noradrenaline. Infusion of vasopressin in patients lacking adrenocortical function was associated with a smaller increase in fractional excretion of sodium by the kidney in comparison with that seen in normal subjects, and the increase in sodium excretion was confined to the period of the infusion. Mineralocorticoid activity was maintained constant during the infusion, although a fall in whole blood packed cell volume, plasma renin activity and plasma noradrenaline were noted, in similarity to the study made in normal subjects. We conclude that changes in mineralocorticoid activity are the main factors contributing to the increase in renal sodium excretion seen during, and after, the continuous infusion of vasopressin in salt- and water-restricted man.

The ophthalmic literature dealing with diseases of the optic nerve, tracts, and visual cortex was reviewed for the period November 1977 to December 1978. Fifty-nine papers of interest to optometrists have been abstracted. Main areas of interest include: role of axoplasmic transport in production of disc edema and cotton-wool spots; ocular effects of local and systemic vascular disturbances; congenital abnormalities of the eye alone and in association with other bodily malformation; field testing, including an ingenious ophthalmoscopic method which can lead to detection of very small scotomas; a new quantitative method for assessing integrity of the optic nerve in multiple sclerosis and related conditions; stimulating questions on the development of optic atrophy and on its relation to retinal vascularity; considerations of acquired and congenital abnormalities of the cavernous sinus and their ocular manifestations; swinging-flashlight test in hemianoptic patients; a case of subacute sclerosing panecephalitis; methods to enhance magnification during opthalmoscopy; methods enabling a closer investigation of the retinal nerve fiber layer.

Twelve patients with medullated retinal nerve fibers are presented. The paper discusses the possible roles played by formation of the ganglion cell axons and lamina cribrosa in the development of medullated retinal nerve fibers. In addition to myopia and amblyopia, patients with medullated retinal nerve fibers may show unusual lens tilts, anterior chamber anomalies, unexpected field losses, and unusual direction of the optic nerve.

Castration of juvenile and photorefractory adult starlings caused no immediate increase in circulating concentrations of LH. In castrated juveniles and adults exposed to natural changes in daylength, plasma LH increased between mid-October and mid-November, although the increase was more rapid in adults. In castrated photorefractory adults, plasma LH increased 3-5 weeks after transfer to artificial short days (8L:16D). In castrated juvenile starlings plasma LH increased 4-6 weeks after transfer to 8L:16D, irrespective of the age of the birds. Birds as young as 17 weeks had high LH concentrations. These results suggest that the reproductive system of juvenile starlings is in the same state as that of photorefractory adults, and therefore the activation of the hypothalamo-pituitary axis for the first time in juveniles is analagous to the termination of photorefractoriness in adults.

Ophthalmoscopic appearances of congenital and acquired presumed ocular toxoplasmosis are described. Four illustrative cases of presumed ocular toxoplasmosis are discussed, with some emphasis on related general health history. Some speculations are offered to account for the varied ophthalmoscopic appearances of these lesions.

The renal response to graded intravenous infusions of arginine vasopressin (AVP) was investigated in a two part study in six volunteers. First, under maximal water diuresis, seven control incremental infusions of AVP were given from zero to 12 fmol min-1 kg-1. Second, the AVP infusions were repeated after pretreatment with indomethacin, 150 mg daily for 36 h. After the AVP infusions, plasma AVP concentrations did not change significantly and remained within the physiological range; in contrast, urinary AVP excretion rate increased steadily. Indomethacin did not alter the plasma or urinary concentrations of AVP. AVP caused a fall in urine flow rate from a state of maximal diuresis to one of maximal antidiuresis. After indomethacin, fractional free water clearance was reduced by an average of 26% at the zero, 2 and 4 fmol min-1 kg-1 infusion rates of AVP. A significant increase in fractional sodium clearance of approximately 50% occurred during the AVP infusions, which was abolished after pretreatment with indomethacin. After indomethacin, urinary prostaglandin E2 (PGE2) excretion rate was reduced by an average of 40% at the zero and 2 fmol min-1 kg-1 infusion rates of AVP. At higher AVP infusion rates, no significant inhibition of PGE2 was observed. Urinary kallikrein excretion rate decreased steadily to one-third of its original value after AVP and this change remained unaltered by indomethacin. The findings show that infusions of AVP, resulting in plasma concentrations in the physiological range, evoke a maximal antidiuretic response, which is accompanied by natriuresis.(ABSTRACT TRUNCATED AT 250 WORDS)

The ophthalmic literature dealing with diseases of the optic nerve, the optic tracts, and the visual cortex was reviewed for the period November 1975 through November 1976. Twenty-nine papers on topics of interest to optometrists were abstracted. The main areas of interest include: papilledema and optic atrophy (with ophthalmoscopic signs of both optic atrophy and papilledema); giant-cell arteritis; papillitis; interesting malformations of the face, palate, and orbital position that occur in conjunction with microphthalmus, situs inversus, and hypoplasia and aplasia of the optic nerve; the proposed association of myopia with unusual eyebrows; myelinated nerve fibers at the nerve head; pigment anomalies; the continuing discussion of nerve-head blood supply; an unexpected cause for nerve-head neovascularization; the importance of the swinging-flashlight test in the diagnosis of glaucoma; an unusual type of glaucomatous cupping; doubts about the peripapillary "halo" as a sign of glaucoma; new uses for old field tests; and new methods of ocular photography.

The dose-response relationships and pharmacokinetics of orally administered 1-desamino-8-D-AVP (DDAVP) were investigated. In water-loaded normal subjects marked reductions in urine flow rate and increases in urinary osmolality occurred. The responses were maximal 2 h after ingestion of 50, 100, and 200 micrograms, and lasted at least 6 h. Plasma DDAVP levels increased in a dose-dependent fashion and its disappearance from the plasma followed an exponential time course, with a half-life 86 to 142 min. In water-loaded adults with central diabetes insipidus (CDI), 200 micrograms oral DDAVP caused marked antidiuresis and mean urinary osmolality increased from 107 mosm/kg to 554 mosm/kg after 3 h. In these patients the effect also lasted at least 6 h. Children with CDI were less sensitive than normal subjects to the 50-microgram dosage and required 100 micrograms orally to achieve a duration of action similar to that resulting from 200 micrograms in adults. Oral DDAVP may be useful for treating some patients with CDI.

A 55-year-old white male underwent an uneventful cataract extraction with implantation of a posterior chamber intraocular lens (IOL) in his left eye. Two years after the cataract surgery, his visual acuity decreased due to opacification of the posterior lens capsule. This report addresses the effect of laser capsulotomy on the patient's visual acuity, intraocular pressure (IOP), and visual field. Although the first two have improved nicely, the size of the last remains considerably below the norm for his phakic contemporaries.

Pulmonary tuberculosis produces a broad spectrum of radiographic abnormalities. During the primary phase of the disease these include pulmonary consolidation (50%), which often involves the middle or lower lobes or the anterior segment of an upper lobe; cavitation (29%) or pneumatocele formation (12%); segmental or lobar atelectasis (18%); pleural effusion (24%); hilar and mediastinal lymphadenopathy (35%); disseminated miliary disease (6%); and a normal chest radiograph (15%). During the postprimary phase of the disease, common abnormalities include exudative and/or fibroproductive parenchymal densities (100%), predominantly in the apical and posterior segments of the upper lobes (91%); cavitation (45%) with bronchogenic spread of disease (21%); marked fibrotic response in the lungs (29%); and pleural effusion, empyema, and fibrosis (18%, 4%, and 41%, respectively). Upper-lobe masslike lesions are seen occasionally (7%); spontaneous pneumothorax and intrathoracic lymphadenopathy are rare (5% each). Common causes of a missed diagnosis of tuberculosis are (1) failure to recognize hilar and mediastinal lymphadenopathy as a manifestation of primary disease in adults, (2) exclusion of tuberculosis because disease predominates in or is limited to the anterior segment of an upper lobe or the basilar segment of a lower lobe, (3) overlooking of minimal fibroproductive lesions or reporting them as inactive, (4) failure to recognize that an upper-lobe mass surrounded by satellite fibroproductive lesions might be tuberculous, and (5) failure to consider healed sequelae of primary disease or a positive purified protein derivative skin test as contributory to identifying the patient's pulmonary disease.

1. The release of arginine vasopressin (AVP) after an osmotic stimulus and head-up tilt was assessed in diabetic subjects with and without autonomic neuropathy. 2. Six diabetic subjects with (DAN +ve) and five without (DAN -ve) evidence of autonomic neuropathy and five normal subjects were infused with 5% (w/v) NaCl at a rate of 0.05 ml min-1 kg-1 body weight for 120 min. Blood pressure, heart rate and plasma AVP were measured over this period. 3. Seven DAN +ve, six DAN -ve and six normal subjects were tilted head-up to 45 degrees for 120 min. Blood pressure, heart rate and plasma AVP were measured during the study. 4. Infusion of 5% (w/v) NaCl produced appropriate rises in plasma osmolality and plasma AVP levels which did not differ between the three groups, confirming the normal osmotic release of AVP in the diabetic subjects. 5. During head-up tilt, there were no differences in AVP responses between the three groups, despite a major hypotensive stimulus in the DAN +ve group. 6. We conclude that osmotic release of AVP is normal in diabetes, but that cardiovascular release of AVP is impaired in diabetic subjects with cardiovascular reflex evidence of autonomic neuropathy, reflecting an afferent defect.

To investigate whether atrial natriuretic peptide (ANP) release during paroxysmal tachycardia is due to increased atrial rate or increased atrial pressure, plasma ANP concentrations were measured during atrial pacing at increasing rates in six alpha-chloralose-anesthetized dogs whose atrial pressures were maintained artificially low by balloon occlusion of the inferior vena cava (IVC). These ANP concentrations were compared with those seen during identical increasing atrial rates in the same dogs without IVC occlusion. During incremental pacing without IVC occlusion, pulmonary wedge pressure (PWP; mean +/- SE) rose progressively from 5.3 +/- 1.6 at 200 to 20.2 +/- 2.3 mmHg at 350 beats/min (P less than 0.01), and right atrial pressure (RAP) rose progressively from 2.5 +/- 0.9 at 200 to 6.7 +/- 2.1 mmHg at 350 beats/min (P less than 0.05). At the same time, arterial and coronary sinus ANP concentrations rose from 116 +/- 55 and 339 +/- 91 to 1,126 +/- 226 and 1,960 +/- 456 pmol/l, respectively (P less than 0.01). In contrast, incremental pacing with IVC occlusion produced no significant increase in PWP and RAP. Arterial and coronary sinus ANP concentrations during IVC occlusion were, respectively, 208 +/- 126 and 388 +/- 159 at 200 and 261 +/- 83 and 345 +/- 80 pmol/l at 350 beats/min (NS). This study demonstrates that the release of ANP during tachycardia is primarily dependent on increased atrial pressure and not atrial rate.

Levels of antibodies in sera from patients with diagnoses of subclinical or established psittacosis infections were determined by the serum neutralization anti-IgG test and by conventional tests. Relatively high levels of serum neutralizing anti-bodies were detected in tests in which anti-IgG was used, whereas conventional tests disclosed only marginal levels of antibody. Use of the serum neutralization anti-IgG test in conjunction with the fluorescent cell-counting technique permitted serum antibody determinations within 24 hr.

1. Responses evoked in the cerebellar cortex following stimulation of caudate nucleus are described.2. The evoked responses recorded from the surface of the cerebellar cortex were found to be of two types, one with a short (4-6 msec) latency and one with a longer (12-17 msec) latency.3. The short latency response was maximal in the lobulus simplex, the longer latency response was maximal in paramedian lobule.4. Following lesions in the inferior olive the longer latency response was absent.5. Recordings from within the cerebellar cortex showed that the short latency response was uniformly distributed throughout the grey matter, the longer latency response was maximal in the region of the Purkinje cell bodies.6. It was concluded that the short latency response was due to activation via the mossy fibres and the longer latency response to activation via the climbing fibres.7. It was found that responses could be evoked in the cerebellum following stimulation of only the latero-ventral part of the caudate nucleus; stimulation of the rest of the nucleus caused no response in the cerebellum. This division of the caudate nucleus into two parts is similar to the subdivision of the caudate nucleus made by other workers using different criteria.

1. Extra- and intracellular recordings have been made of single units in the caudate nucleus of the cat, anaesthetized with alpha chloralose.2. Pentobarbitone was shown to depress the spontaneous activity and responses of units in the caudate nucleus.3. Spontaneous activity of units usually took the form of single spikes or bursts of up to four spikes occurring every 100-300 msec.4. The response to electrical stimulation of limb nerves was a burst of 1-4 spikes after a latency of about 30 msec. Convergence from all four limbs on to single units was observed. It is shown that muscle afferents do not cause these responses.5. Post stimulus histograms of spontaneously active units show, following stimulation of the limb nerves, recurring cycles of excitation and inhibition at a rate of 3-4 c/s and lasting for several seconds. It is suggested that each stimulus synchronizes the normally rhythmic spontaneous activity.6. Similar responses have been obtained following stimulation by clicks and flashes of light.7. Stimulation of the ipsilateral cerebral cortex gave excitatory and inhibitory responses similar to those described above.8. Possible mechanisms for these responses and their significance are discussed.

1. Extra- and intracellular responses of single units in the inferior olive following stimulation of the cerebellum, limb nerves, skin receptors, the caudate nucleus and cerebral cortex have been described.2. Responses following cerebellar stimulation were assumed to be antidromic spikes when they occurred after a latency of less than 4 msec and followed stimulus frequencies greater than 220/sec. Other responses with longer latencies were thought to be transynaptic. Evidence for recurrent inhibition of the Renshaw type is given.3. Following limb nerve stimulation two types of units have been observed; units responding after a short latency and to stimulation of one limb only and units responding with a long latency following stimulation of one or more of the limbs.4. Units responding to stimulation of the limb nerve after a short latency could often be excited by hair movement and/or light touch on the pads. Other units were excited by pinching and others could not be excited by a physiological stimulus. The receptive field of these units was small and there was no evidence of fringe inhibition.5. Most units observed represented the contralateral forelimb but there was a significant number of units representing the ipsilateral limbs.6. The caudato-olivary pathway has been shown to be excitatory. Short latency limb units do not receive afferents from the caudate nucleus.7. Afferents from the motor cortex excite units in the inferior olive. A remarkable correlation of latencies of responses from both the cerebral cortex and the limbs on to individual units has been described.8. The results suggest a complex organization of neurones within the inferior olive. A possible plan of the organization of neurones is given and discussed.