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Biomedical subjects

R Marcuson

Publications and source records attributed to R Marcuson.

11 recordsLinked to original sources
PubMed1994

Vasculitis in patients with systemic sclerosis and severe digital ischaemia requiring amputation.

OBJECTIVES: To document the incidence of histological vasculitis in amputation specimens from patients with severe digital ischaemia secondary to systemic sclerosis (SSc), and to look for an association between anticardiolipin (aCL) antibodies and severe digital ischaemia in SSc. METHODS: This was a retrospective review of patients with SSc who underwent amputation for digital ischaemia over a three year period. RESULTS: Five of nine patients had histological vasculitis, four of whom had aCL antibodies, although these were not present in high titre. CONCLUSION: Vasculitis does occur in SSc, at least in that subgroup with severe peripheral ischaemia. These findings could have implications for treatment of this subgroup of patients with SSc.

Adult↗
PubMed1986

Age-dependent changes in proteins of Drosophila melanogaster.

Several molecular theories of aging postulate that there are age-dependent changes in gene expression and that these changes contribute to the reduction in the viability of senescent cells. High-resolution, semiautomated, quantitative two-dimensional gel electrophoresis of many soluble proteins was used to test this hypothesis in Drosophila. Two-dimensional protein gel patterns were analyzed for each of three age groups of [(35)S]methionine-labeled adult male Drosophila melanogaster, which, except for their spermatocytes, consist entirely of fixed postmitotic cells. Seven relatively abundant polypeptides expressed in middle-aged (28-day-old) flies were absent in both young(10-day-old) and old (44-day-old) flies. Quantitative analyses of an additional 100 polypeptides were carried out by computer-assisted microdensitometry of fluorograms of the gel preparations. These analyses revealed a significant age-related heterogeneity in the quantitative distribution of radiolabel in these proteins. The data indicate that the qualitative pattern of gene expression is identical in young and old flies, but that profound quantitative changes occur in the expression of proteins during the Drosophila life-span.

Aging↗
PubMed1985

Effect of dietary ascorbic acid on the incidence of spontaneous mammary tumors in RIII mice.

A study of the effect of different amounts of L-ascorbic acid (vitamin C), between 0.076% and 8.3%, contained in the food has been carried out with ten groups of RIII mice (seven ascorbic acid and three control groups), with 50 mice in each group. With an increase in the amount of ascorbic acid there is a highly significant decrease in the first-order rate constant for appearance of the first spontaneous mammary tumor after the lag time to detection by palpation. There is also an increase in the lag time. The mean body weight and mean food intake were not significantly different for the seven ascorbic acid groups. Striking differences were observed between the 0.076% ascorbic acid and the control groups (which synthesize the vitamin): smaller food intake, decreased lag time, and increased rate constant of appearance of the first mammary tumor. This comparison cannot be made experimentally for guinea pigs and primates because the control groups would develop scurvy.

Animals↗
PubMed1983

Profile analysis of volcano field ionization mass spectra of urine from mice with sarcoma I transplanted by intraperitoneal inoculation.

A group of 20 inbred mice were inoculated intraperitoneally with sarcoma I cells. Urine specimens were collected before and after inoculation from this group as well as from a group of 20 mice for controls. Mass profiles of these groups were obtained by volcano field ion mass spectrometry and compared. Significant differences in average normalized mass peaks between the two groups after inoculations are observed for most of the peaks analysed from mass 84 to 313. There is sufficient diagnostic power in the mass profiles to permit unambiguous separation of the diseased mice from the healthy ones.

Animals↗
PubMed1982

Effects of intake of L-ascorbic acid on the incidence of dermal neoplasms induced in mice by ultraviolet light.

We have carried out a study of large malignant skin tumors (squamous cell carcinomas) and other lesions in hairless mice (groups of 38-45) intermittently exposed to ultraviolet light over a period of 15 weeks, beginning when the mice were about 10 weeks old. The several groups were given a standard diet with 0%, 0.3%, 5%, and 10% added L-ascorbic acid (vitamin C) throughout the study. No lesions developed in unirradiated control groups. The lesions were counted every 14 days for 4 months, beginning 4 weeks before the end of the period of irradiation. The observed incidence of lesions of several sizes during successive time periods was analyzed by the statistical method recommended by a committee of the International Agency for Research on Cancer. A pronounced effect of vitamin C in decreasing the incidence and delaying the onset of the malignant lesions was observed with high statistical significance.

Animals↗
PubMed1982

Normalization and reproducibility of mass profiles in the detection of individual differences from urine.

The mass profiles of urine samples and their reproducibility (coefficient of variation) obtained by field-ionization mass spectrometry (volcano source) depend upon the choice of normalization method. We compared six different normalization techniques in terms of improved reproducibility and sensitivity. Several simple procedures markedly improved reproducibility while preserving the high degree of sensitivity. Although these procedures gave similar and satisfactory results, others were clearly inferior and are not recommended for clinical profiling.

Adult↗
PubMed1981

A comparison of the Sphygmetrics SR-2 Automatic Blood Pressure Recorder to the mercury sphygmomanometer in population studies.

The Sphygmetrics SR-2 Automatic Blood Pressure Recorder uses an infrasonic technique for detecting artery wall motion to estimate systemic arterial pressure and produces a permanent record of the results. It therefore is potentially useful in reducing observer bias in epidemiologic studies of blood pressure (BP). Two blood pressures were recorded in 21 men and 50 women using the SR-2 simultaneously with two auscultators using a biaural stethoscope and mercury syhgmomanometer. The SR-2 measured slightly higher systolic nd slightly lower diastolic pressures on average, but the differences were not significant. The two auscultators were highly correlated with one another (r = 0.99 systolic/0.97 diastolic) and with the SR-2 (0.93 and 0.92 for systolic, 0.84 and 0.85 for diastolic). The correlations were unrelated to sex, age, or antihypertensive medication status, but the correlations between th SR-2 and either auscultator for diastolic BP were quite low (0.36, 0.55) in subjects whose relative weight was below 1.0. Interpretation of the SR-2 disc was very reliable, with inter- and intra-reader correlations being 0.99 for systolic and 0.84 to 0.94 for diastolic. The SR-2 was found to be comparable to auscultation in estimating systolic BP in a heterogeneous population which has the advantages of reducing observer bias and producing a permanent record. Its use in estimating diastolic pressure in thin individuals and children needs further evaluation.

Adult↗
PubMed1979

Clinical importance of directional statistics for electrocardiographic differentiation of smoking habits.

Statistical methods for the analysis of directional data are of relatively recent origin and have not been generally applied in clinical investigations where they are appropriate. This study compares spherical means and standard deviations for directional polarcardiographic variables with the linear means and standard deviations of the same variables for a typical industrial cohort of male white collar workers. Normal subjects were classified by smoking status and by independent clinical evidence of the presence of CHD, and both directional and linear statistics are applied to compare the PCG variables in these groups. Directional statistics more accurately define the spherical means and variances of heart vectors and thereby permit more reliable differentiation of directions, or angles to aid diagnosis.

Adult↗
PubMedDate not supplied

Simplified computation of the multivariate permutation test for arbitrarily censored survival data.

This paper points out that the permutational covariance matrix of the multivariate generalization of Gehan's test on censored survival data enjoys the useful property that a generalized inverse may be explicitly computed. This leads to an exceedingly simple formula for the test statistic. The ease of the resulting calculations is displayed with a brief example from exercise stress testing.

Exercise Test↗