Delayed basal hyperpolarization of cat retinal pigment epithelium and its relation to the fast oscillation of the DC electroretinogram.

Previous work has shown that the cat retinal pigment epithelium (RPE) is the source of two potential changes that follow the absorption of light by photoreceptors: a hyperpolarization of the apical membrane, peaking in 2-4 s, which leads to the RPE component of the electroretinogram (ERG) c-wave, and a depolarization of the basal membrane, peaking in 5 min, which leads to the light peak. This paper describes a new basal membrane response of intermediate time course, called the delayed basal hyperpolarization. Isolation of this response from other RPE potentials showed that with maintained illumination the hyperpolarization begins approximately 2 s after light onset, peaks in 20 s, and slowly ends as the membrane repolarizes over the next 60 s.

Changes in apical [K+] produce delayed basal membrane responses of the retinal pigment epithelium in the gecko.

We describe here a new retinal pigment epithelium (RPE) response, a delayed hyperpolarization of the RPE basal membrane, which is initiated by the light-evoked decrease of [K+]o in the subretinal space. This occurs in addition to an apical hyperpolarization previously described in cat (Steinberg et al., 1970; Schmidt and Steinberg, 1971) and in bullfrog (Oakley et al.

Differential effects of pCO2 and pH on the ERG and light peak of the perfused cat eye.

Hypercapnia has been shown to depress the ERG b-wave and also the light peak in vivo. To test if acidosis induced by elevation pCO2 affects the retina differently from that induced by HCl we used bicarbonate buffered and HEPES buffered perfusates, respectively, in isolated perfused feline eyes. Any decrease in pH from 7.

Sites of phosphorylation and mutation in regulatory subunit of cyclic AMP-dependent protein kinase from S49 mouse lymphoma cells: mapping to structural domains.

A novel peptide mapping approach has been used to map sites of charge modification to major structural domains of regulatory subunit (R) of type I cAMP-dependent protein kinase from S49 mouse lymphoma cells. Proteolytic fragments of crude, radiolabeled R were purified by cAMP affinity chromatography and displayed by two-dimensional polyacrylamide gel electrophoresis. [35S]methionine-labeled peptides containing sites of mutation or phosphorylation exhibited charge heterogeneity attributable to the modification.

Release of neuron specific enolase (NSE) in cerebrospinal fluid following experimental lesions of the rat brain.

Neuron-specific enolase (NSE) levels were measured by sandwich enzymo-immunoassay as well as by enzymatic assay in rat cerebrospinal fluid (CSF), following mechanical lesions of the brain tissue. Significant increases of NSE were observed in CSF, with a peak 2 h following lesions located near the lateral ventricle. Values returned to normal around 48 h later.

Effects of hypoxia and hypercapnia on the light peak and electroretinogram of the cat.

The effects of systemic hypoxia and hypercapnia on the standing potential, light peak, and electro-retinogram (ERG) of the intact cat eye were studied. DC recordings were made in the vitreous humor. The amplitude and waveform of the light peak were surprisingly sensitive to hypoxia.

Three light-evoked responses of the retinal pigment epithelium.

This paper summarizes our findings on light-evoked changes in retinal pigment epithelial cell (RPE) membrane potentials. Experiments were performed on the eye of the anesthetized or decerebrate cat and on isolated tissues from the eyes of a lizard, Gekko gekko, and a frog, Rana catesbeiana. In cat, as was previously shown, the RPE apical membrane potential responds to changes in [K+]0 in the subretinal space.

The human autologous mixed lymphocyte reaction. II. Analysis of activation and proliferation.

In this study, we have used cell cycle analysis as an independent measure of proliferation and the 4F2 marker to enumerate activated T cells. T-cell proliferation increased gradually throughout the 7-day culture. The degree of proliferation correlated very strongly (r = 0 .

Changes in extracellular potassium and calcium in rat cerebellar cortex related to local inhibition of the sodium pump.

Extracellular K+, Ca2+, and Na+ ([K+]e, [Ca2+]e, [Na+]e) were recorded with ion selective microelectrodes in the cerebellar cortex of urethane-anesthetized rats. Superfusion of the cerebellum with artificial cerebrospinal fluid containing K-strophanthidin (10(-6)-10(-4) mol/l) or other cardioactive steroids, known to be inhibitors of the sodium/potassium pump, had the following effects: elevation of resting [K+]e, reduction of poststimulus K+-undershoots, decrease of resting [Ca2+]e and [Na+]e. For instance, at 3 X 10(-5) mol/l K-strophanthidin within the superfusion solution (the unknown intracerebellar concentration being certainly much smaller), [K+]e was elevated up to 130% and [Ca2+]e reduced to 70% of their resting values.

Origin and sensitivity of the light peak in the intact cat eye.

1. The light peak is a large light-induced change in the DC potential across the eye (standing potential) that reaches its maximum in 5-13 min in mammals. The light peak of the intact cat eye was studied in order to define its cellular origin and stimulus-response characteristics.

Origin of the light peak: in vitro study of Gekko gekko.

1. The light peak is a large, light-evoked increase in standing potential recorded in mammals, birds and reptiles. We have studied the cellular origin of the light peak in an in vitro preparation of neural retina-pigment epithelium (r.

Phagosome degradation in the tapetal retinal pigment epithelium of the opossum.

Ultrastructural and cytochemical features of phagosome degradation were examined in the tapetal retinal pigment epithelium (RPE) of the opossum. Didelphis virginiana. The tapetal RPE cells of the opossum measure as much as 100 micrometers in thickness, and the phagosomes traverse these cells so as to occupy a narrow region along the basal border.

Phagosome movement and the diurnal pattern of phagocytosis in the tapetal retinal pigment epithelium of the opossum.

The diurnal pattern of phagocytosis and the movement of phagosomes was studied in the tapetal retinal pigment epithelium (RPE) of the opossum, Didelphis virginiana. The opossum was chosen because of its rod-dominated retina and large tapetal RPE cells (up to 100 micrometers in height), which are packed with reflective granules and contain little melanin. Thus phagosomes and their passage from apical to basal cell border were easily seen.

Scoliosis in the elderly: a follow-up study.

A follow-up x-ray study of 554 subjects aged between 50 and 84 years has been carried out to determine the appearance, presence, and progression of scoliosis in the elderly and its relationship to osteoporosis and back pain. The subjects were chosen from a population group of 3600 subjects examined 7 to 13 years previously in the same investigators. Some degree of scoliosis was found in 70% of the subjects, and curves of 10 degrees or more in approximately 30%.

Osteoarthritis of the hip joint and osteoporosis: a radiological study in a random population sample in Jerusalem.

The prevalence of osteoarthritis of the hip and osteoporosis of the pelvis were examined in a random population sample in Jerusalem. Of the subjects reviewed, 16.1% showed osteoporosis of the pelvis, while osteoarthritis was noted in 4.

Origin and organization of pigment epithelial apical projections to cones in cat retina.

The apical surface of the retinal pigment epithelial cells (RPE) in the cat extend long sheetlike membranes that wrap concentrically above and around cone outer segments forming the cone sheath. The origin and organization of these sheetlike projections were studied in serial sections by electron microscopy. The apical surface of the RPE cells was found to consist of a thin zone of anastomosing ridges, or microplicae, from which longer projections extend.

Neuron-specific enolase as a marker of neuronal lesions during various comas in man.

The detection of neuron-specific enolase in biological fluids has been investigated as an indirect marker of neuronal damage in man. This protein was measured by a sandwich enzymoimmunoassay in serums and cerebrospinal fluids from patients with consciousness disorders of various aetiologies. Neuron-specific enolase level was significantly increased in sera from patients with comas resulting from anoxemia, head injury, septic state, cirrhosis and fulminant hepatitis.

Melanosome metabolism in the retinal pigmented epithelium of the opossum.

Melanosomal metabolism, including both formation and degradation of melanosomes, was studied in the retinal pigmented epithelium (RPE) of the adult opossum. The majority of the observations were made on a transitional zone between the tapetal and non-tapetal RPE, the region where melanosome metabolism was at its highest level. Formation of melanosomes, demonstrated ultrastructurally by the presence of stage-II and -III premelanosomes, was also examined autoradiographically following the incorporation of the melanin precursor, dihydroxyphenylalanine.

Effects of maintained illumination upon [K+]0 in the subretinal space of the frog retina.

Changes in extracellular potassium ion concentration, [K+]0, were measured in the subretinal space of an in vitro preparation of bullfrog retina, pigment epithelium and choroid. In response to maintained illumination [K+]0 fell to a minimum value in 30-40 sec, and then began to recover, reaching a steady-state approximately 10 min after light onset. At light offset, [K+]0 overshot the dark-adapted baseline before recovering.

Potassium transport across the frog retinal pigment epithelium.

Previous experiments indicate that the apical membrane of the frog retinal pigment epithelium contains electrogenic Na:K pumps. In the present experiments net potassium and rubidium transport across the epithelium was measured as a function of extracellular potassium (rubidium) concentration, [K]0 ( [Rb]0). The net rate of retina-to-choroid 42K(86Rb) transport increased monotonically as [K]0 ( [Rb]0) increased from approximately 0.

[Anorexia nervosa and schizophrenia in a pair of monozygotic twins].

The case report describes two 20-year-old monozygotic twin sisters who have been suffering from the symptoms of primary anorexia nervosa for the last 10 years. Usually the disease manifested itself in such a manner that the twin who was currently in the mother's favour showed no signs of anorexia, whereas the other was severely afflicted. Occasionally, however, both girls suffered from the same anorectic symptoms at the same time.