Effects of hydration and dehydration on body composition analysis: a comparative study of bioelectric impedance analysis and hydrodensitometry.

Since 1983, bioelectric impedance has been researched with respect to its validity and reliability in the determination of body composition. It continues to be compared to hydrostatic weighing, the anthropometric "gold standard". This study was designed to investigate the relationship between bioelectric impedance analysis (BIA) and hydrodensitometry (HW) under three conditions: control, hydration and dehydration. Caucasian males (aged 18-44 years) served as subjects (n = 10). Body composition was determined by BIA and HW before intervention, 30 minutes post-hydration, and following a combination of exercise and sitting in a steam room to decrease body weight by two to four percent (mean = 2.81%). Statistical treatment by two-way analysis of variance for repeated measures revealed that although there were no significant differences between the two techniques of body composition determination under any of the three conditions, there was a statistically significant decrease in percent body fat determined in the dehydrated state as compared to the control and hydrated conditions. Recommendations include the determination of hydration state prior to engaging in body composition analysis by either method.     

Neurosurgery image manager

Computer technology has become standard in many areas of medical practice, but computer-assisted instruction has not replaced standard textbooks and didactic lectures. This paper describes the development of a computer image-based educational system designed for neurosurgical instruction. The advantages and applications of this system for both clinical and academic use and the required software and hardware requirements are delineated. This computerized tutorial can organize and manipulate large amounts of data. The Neurosurgery Image Manager system contains an introductory help section, a self-assessment test in neurosurgery, and a data base of images from the video disc "The Slice of Life," produced at the University of Utah. Questions are taken from the Self-Assessment in Neurological Surgery series. Additionally, the system contains a reference index for all material in the tutorial, a scored clinical problems section, and a several hundred word glossary. The system is programmed using the Macintosh Hypercard authoring system. Large data bases can be manipulated and linked with graphics, text, and peripherals. Images are stored using the MacVision II digitizing system. The hardware necessary to operate the system and the method of implementation of Neurosurgery Image Manager are described. The prototype Neurosurgery Image Manager has been accepted by the Joint Committee on Education of the American Association of Neurological Surgeons and Congress of Neurological Surgeons as one of the computer formats for the next self-assessment tests.     

Analysis of the genes involved in the insulin transmembrane mitogenic signal in Chinese hamster ovary cells, CHO-K1, utilizing insulin-independent mutants.

CHO-K1 cells, wild type (WT), grow in a defined medium with insulin as the only essential hormone. When starved for insulin, these cells accumulate in G0/G1 stage. Insulin binding to its receptor stimulates DNA synthesis and cell division and induces an increase in abundance of mRNA for c-fos, c-jun, Krox-20, Krox-24 (zif/268), fra-1, jun-B, c-myc, and JE. The kinetics of induction of these genes are similar to that shown with serum induction of 3T3. These genes show maximum stimulation at insulin concentrations of 20, 160, or 320 ng/ml and their expression is inhibited at higher concentrations. The addition of cycloheximide results in superinduction. The WT and insulin-independent mutants show no detectable signal for KC, fos-b, or nur77 and no increase over the basal level of pI-15, probably eliminating these genes as participants in the insulin mitogenic signal. These mutants synthesize DNA in the absence of insulin at rates that vary from 4 to 12 times that of the quiescent (insulin unstimulated) WT and are further inducible by insulin. The mutants have "constitutive" levels of Krox-24 (zif/268), fra-1, jun-B, c-myc, and JE (INS-type 2 genes) mRNAs that vary from mutant to mutant, reaching a maximum of an 8-fold increase for fra-1 and JE over the quiescent WT levels. There were no detectable levels of mRNA for genes c-fos and Krox-20 and no increase in level of mRNA for c-jun (INS-type 1 genes) as compared to the quiescent WT. Thus, although these INS-type 1 and type 2 genes may be involved in the full insulin mitogenic signal, the constitutive up-regulation of only genes in INS-type 2 is sufficient for insulin-independent DNA synthesis and cell division. Analysis of hybrids constructed between WT and mutant 27 indicate that the mutant phenotype is recessive, pointing to the existence of a regulatory gene producing a negative regulator.     

Measuring input prices for physicians: the revised Medicare Economic Index

Medicare payments for physician services under Part B were historically restrained by capping prevailing charges using the Medicare Economic Index (MEI). The MEI, an input price index for physician services that incorporates an adjustment for economywide labor productivity, has not undergone a major revision since 1975. The MEI is an important determinant of the annual volume performance standard that will be used to set aggregate increases in the revised system for paying physicians under Medicare beginning in 1992. The MEI will also be used in establishing the annual changes to the payment conversion factors under the new payment system.     

6-125I-iodo-2-methyl-1,4-naphthoquinol bis (diammonium phosphate) as a potential radio-halogenated anti-cancer agent: In vitro investigations and possible clinical implications

6-¹²⁵I-iodo-2-methyl-1,4-naphthoquinol bis (diammonium phosphate) (6-¹²⁵I-iodo-MNDP) has been synthesised and studied as the prototype of a class of potential radio-halogenated anti-cancer agents. The incorporated ¹²⁵I provides Auger electron radiations which behave like high LET radiations in the treatment of tumours, though the accompanying X- and -radiations make an undersirable contribution to the total body dose. The in vitro experiments reported show that 6-¹²⁵I-iodo-MNDP is selectively concentrated in the cells of some human malignant tumours by factor of about 15 to 20 or more in relation to the cells of normal origin studied. On the basis of dosimetric considerations and comparison with clinical treatment with tritiated methylnaphthoquinol diphosphate, practical dosage of 6-¹²⁵I-iodo-MNDP is suggested and clinical indications and safety of use are discussed. The types of tumour of particular interest are inoperable cases of carcinoma of the colon, carcinoma of the pancreas, malignant melanoma and osteosarcoma. Further investigations are in progress.Beit Memorial Fellow for Medical Research     

Altered thiol status in patients with rheumatoid arthritis

Summary The thiol status of patients with rheumatoid arthritis is significantly different from that of controls. Plasma thiol levels are lower, albumin thiol reactivity is altered and intracellular thiol levels measured after hemoglobin precipitation are increased. These variations correlate with other indices of disease severity and are one measure of a disturbance in the degree of oxidation of the blood. Penicillamine, in common with other effective therapeutic agents, produces an increase in serum thiol concentration. It causes a greater effect on serum thiol reactivity than other drugs and in particular it increases fast reacting thiol levels without significantly altering the slow reacting thiol level.