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Biomedical subjects

I Gordon

Publications and source records attributed to I Gordon.

282 records · Page 16Linked to original sources
PubMed1969

Temperature of compensation: significance for virus in- activation.

The purpose of this report is to call attention to the probable biological utility of a physical constant, the temperature of compensation (T(c)) or isokinetic temperature. T(c) has hitherto not been used in biological research. It is defined as the temperature at which a series of Arrhenius plots, related by variation of a single parameter, pass through a common point. Such systems demonstrate the so-called compensation effect and show linear variation of change in enthalpy with change in entropy; the slope [unk] H/[unk]S is T(c). Related reactions in which, for example, solvent change or structural change of the reactants does not change the mechanism of the reaction or the nature of the transition state exhibit an identical T(c). The system used in this study was a complex one, i.e., protection against thermal inactivation of Sindbis virus by HPO(4) (=) and SO(4) (=). The time-rate constant of loss of infectivity was determined at different temperatures for virus suspended in different salt concentrations at constant pH. The compensation effect was demonstrated and T(c) was found to be approximately 57 degrees C for virus inactivation in both Na(2)HPO(4) and MgSO(4) solutions. The intercept of a DeltaSdouble dagger/DeltaHdouble dagger plot, defined as the constant B, also was the same for the two salts. We suggest that determination of T(c) in biological systems might be of value in (1) establishment of whether an observed phenomenon results from the same process or mechanism as another observed phenomenon; (2) prediction of rates or other behavior under relevant conditions; and (3) classification.

Arboviruses↗
PubMed1966

Effect of interferon on polymerization of single-stranded and double-stranded mengovirus ribonucleic acid.

Gordon, Irving (University of Southern California, Los Angeles), Sara S. Chenault, Douglas Stevenson, and Jean D. Acton. Effect of interferon on polymerization of single-stranded and double-stranded mengovirus ribonucleic acid. J. Bacteriol. 91:1230-1238. 1966.-The effect of interferon on actinomycin-resistant mengovirus ribonucleic acid (RNA) replication in L cells was investigated to determine whether defective or partially polymerized RNA products were made and whether synthesis of any specific class of virus RNA was prevented. RNA labeled with uridine-C(14) was extracted in hot and cold phenol and analyzed by zonal sucrose density centrifugation. Both single- and double-stranded infectious RNA peaks were identified. Interferon treatment caused almost complete depression of uridine-C(14) incorporation throughout linear sucrose gradients except in the 4S region, and no infectivity was detectable in any fraction. These inhibitory effects are attributable to the action of interferon, because they were reversed when cultures were treated with actinomycin D simultaneously with interferon. The results, with those of other investigators, indicate that the step at which interferon interrupts virus multiplication is between the events immediately after uncoating and the formation of template "minus" strands; under the conditions of our experiments, no partially polymerized virus RNA products were made.

Carbon Isotopes↗
PubMed1965

Mechanism of Polykaryocytosis Associated with Noncytopathic Infection by Measles Virus.

Atherton, John G. (University of Southern California, Los Angeles), Sotiros G. Chaparas, Martha Cremer, and Irving Gordon. Mechanism of polykaryocytosis associated with noncytopathic infection by measles virus. J. Bacteriol. 90:213-219. 1965.-Infection with a measles virus variant resulted not only in formation of polykaryocytes (PK) but also in formation of multicellular immunofluorescent foci (IFF) in which no cytopathic effect could be detected. The ratio of IFF to PK changed from 27 to 4 during the first passage and remained 4 after a second passage. PK were plaques. Plaque assay was linear in the presence of IFF. To investigate the mechanism of PK formation, radioautography was done on cells pulse-labeled with tritiated thymidine before virus multiplication began. The results showed that PK were formed by fusion; there were no PK whose nuclei contained no label, and the proportion of labeled nuclei (32%) and distribution of grain counts was the same in PK as in uninvolved cells, ruling out nuclear replication without concomitant cytoplasmic membrane formation as the mechanism of formation of these PK. Early in PK development, neutral red uptake was markedly increased ("red" plaques). As PK matured, hyperchromicity disappeared ("white" plaques). This sequence provided an index of rate of evolution of PK. Rate of PK maturation was more rapid at 37 than at 32 C.

Journal Article↗
PubMedDate not supplied

Biochemical and cognitive studies of apolipoprotein-E-deficient mice.

Apolipoprotein-E-deficient mice provide a useful model system for studying the role of apolipoprotein E (apoE) in brain function. In the present study, we characterized the cholinergic function of these mice and the extent of phosphorylation of their cytoskeletal protein tau. Morris water maze tasks revealed deficits in working memory that were accompanied by a specific decrease in hippocampal and cortical choline acetyltransferase activities. Immunoblot experiments utilizing native and dephosphorylated tau and antibodies directed against specific phosphorylated and unphosphorylated tau epitopes revealed that tau of the apoE-deficient mice is hyperphosphorylated. These results show that apoE-deficient mice have cognitive cholinergic and cytoskeletal derangements and point out the importance of this model for studying the role of apoE in neuronal function.

Animals↗
PubMedDate not supplied

Comparison of rural and urban certified nurse-midwives in Arizona.

A survey of certified nurse-midwives (CNMs) in Arizona was carried out in 1990 to provide data for maternity service planning in the state. Information was gathered on location and scope of CNM practice, barriers to practice, and the contribution of CNMs to maternity care. Demographic and clinical practice characteristics of urban and rural CNMs were also compared. Urban and rural CNMs are significantly different in terms of education (urban CNMs are much more likely to have master's degrees) and number of years since first certification (urban CNMs have been certified significantly longer). Rural midwives are more likely to be under the age of 40. Health services provided by urban and rural CNMs were compared with each other and with national data. Midwives in rural areas of Arizona are more likely to provide comprehensive nurse-midwifery services than are either urban Arizona midwives or U.S. midwives as a whole. Urban and rural CNMs described lack of physician backup as a major barrier to nurse-midwifery practice in rural areas. Lack of hospital privileges was another major obstacle noted by rural nurse-midwives. Arizona CNMs felt they could provide comprehensive, cost-effective maternity services in rural areas that would improve access to care, patient satisfaction, and maternal and child health outcomes.

Adult↗
PubMedDate not supplied

Aspects of the hyoid-larynx complex in forensic pathology.

Post-mortem radiological studies of the hyoid-larynx complex on excised specimens were undertaken. The post-mortem specimens were fixed to polysterene boards by ratio-translucent plastic pins. Radiological examinations revealed a fracture of the left greater cornu of the hyoid bone in a case of suicidal hanging; a fracture through the calcified right superior cornu of the thyroid cartilage in a case of blunt trauma to the left side of the head and neck; and a fracture artefact through the middle of the left greater cornu of the hyoid bone through compression of the structure by manipulation during the process of removal of the neck structures. In each instance the fracture sites were exposed and photographed. The use of a technique which permits a radiological examination of free dissected specimens of the hyoid-larynx complex has many advantages in the medicolegal investigations of injuries of the neck.

Forensic Medicine↗