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Biomedical subjects

R Levine

Publications and source records attributed to R Levine.

At least 127 records · Page 7Linked to original sources
PubMed1981

Comparison of the accuracy of the Binkhorst, Colenbrander, and SRK implant power prediction formulas.

The prediction accuracy of the Binkhorst, Colenbrander, and SRK formulas were compared in five series from different sources totalling 654 cases. The SRK formula was superior to both the other formulas by having a smaller average error per case, a smaller range of error from highest minus to highest plus, and a smaller proportion of cases with greater than 2 diopters (D) of error in all five series studied. In four of the five series, the SRK formula also had the greatest proportion of cases with less than 1 D of error. The Colenbrander formula was superior to the Binkhorst formula in all five series with regard to average error, proportion of cases with less than 1 D of error, and proportion of cases with more than 2 D of error. The range of error from highest minus to highest plus was equivalent with the two formulas. All available published literature on the accuracy of implant power prediction formulas was reviewed and appears to support our findings.

Humans↗
PubMed1981

Haloperidol-induced reduction of nigral substance P-like immunoreactivity: a probe for the interactions between dopamine and substance P neuronal systems.

Protracted blockade of dopamine receptors by haloperidol has been shown to cause a reduction in nigral content of substance P-like immunoreactivity (SPLI). This pharmacological effect is used to study the mechanisms whereby the dopaminergic and substance P systems interact. Data presented in this paper suggest that 1) blockade of dopamine postsynaptic receptors alters nigral SPLI levels associated with the substance P striatal-nigral loop, 2) destruction of the nigral-striatal dopaminergic pathway results in changes in nigral content of SPLI similar to that induced by haloperidol, 3) several weeks after nigral-striatal lesions, compensatory mechanisms mediate a return of nigral SPLI content to control levels and 4) substance P striatal-nigral circuits continue to respond to dopaminergic input after kainic acid lesions in the anterior striatum, whereas properly placed mechanical striatal-nigral lesions appear to be effective in preventing this interaction. The data support a dynamic role for striatal-nigral substance P fibers in the extrapyramidal circuitry and suggest that his pathway must be accounted for when studying the interactions of transmitter systems within this locomotor center.

Animals↗
PubMed1980

Assignment of functions to segments of the DsRNA genome of the Ustilago virus.

The genome of the 3 Ustilago maydis viruses, known to be associated with the "killer phenomenon", is segmented. The distribution of the viral functions on different segments has been partly resolved. The reported comparative study, of a series of mutants with deleted segments of the genome and of hybrid variants containing segments of the related viruses, provides additional information on the location of various functions and on the interrelations among the different segments. The data indicates that the functions related to the maintenance of the viral information are located on the H segments. Among these segments some function overlap exists. The maintenance of the M and L segments is dependent on the functions located on the H segments. The functions related to the killer phenotype are distributed on the M2 and L1 segments. These functions include the determination of the killer specificity. The H segments play no role in the determination of the killer specificity and the specificity is determined by the M2 segment. The L segment is essential for the expression of the killer phenotype but it is suggested that the information for the toxin resides in the M2 segment.

Basidiomycota↗
PubMed1980

Endogenous dissemination of genital Herpesvirus hominis type 2 to the eye.

A 33-year-old man developed Herpesvirus hominis type 2 (HVH-2) eye disease following a herpetic lesion of the penis. The sequence of ocular involvement suggested that the virus had been transmitted endogenously from the genital lesion: granulomatous iritis was followed by interstitial keratitis and then by dendritic keratitis. Recurrent bacterial ulcers ultimately required a conjunctival flap. The course of this man's ocular disease as well as those of other reported cases of HVH-2 adult eye infections appeared to be more severe and prolonged than that of the average patient with ocular herpes type 1 infection.

Adult↗
PubMed1980

Effect of corticosterone on insulin and glucagon secretion by the isolated perfused rat pancreas.

The in vitro effect of corticosterone in insulin and glucagon secretion has been examined in the isolated perfused rat pancreas preparation. COrticosterone at physiological concentrations was found to inhibit acutely and strongly the secretion of insulin induced by both glucose and arginine and to potentiate the output of glucagon in a glucose-free medium or when induced by arginine. Phentolamine, an alpha-adrenergic blocking agent, diminished the strong inhibitory effect of corticosterone on insulin secretion. The present results demonstrate that corticosterone has direct effects on pancreatic islet cells, and they suggest that the inhibition of insulin secretion is to some extent related to the alpha-adrenergic receptors.

Animals↗
PubMed1980

Aging and CSF hydroxylase cofactor.

The level of cerebrospinal fluid (CSF) hydroxylase cofactor activity was measured in 34 neurologically normal patients and analyzed according to age. Levels declined by approximately one-third over a 40-year span, probably reflecting loss of aminergic neurons. Fourteen patients with Parkinson disease all tended to have lower values than age-matched controls. Among Parkinson patients with the same order of disability, younger cases had higher CSF concentratons of hydroxylase cofactor than older patients.

Adult↗
PubMed1979

Nuclease activity associated with the Ustilago maydis virus induced killer proteins.

An in vitro nuclease activity was found to be associated with the purified killer proteins of Ustilago maydis. The proteins are effective against single stranded RNA, single and double stranded DNA. Endonucleolytic activity was confirmed by cleavage of circular molecules of 0x174 and PM2. Double stranded RNA did not appear to serve as a substrate.

Basidiomycota↗