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Biomedical subjects

R Margolis

Publications and source records attributed to R Margolis.

At least 37 records · Page 2Linked to original sources
PubMed1986

In vivo inflammatory activity of epidermal cell-derived thymocyte activating factor and recombinant interleukin 1 in the mouse.

Epidermal cell-derived thymocyte activating factor (ETAF), a cytokine produced by keratinocytes, has previously been shown to be biochemically and functionally very similar, if not identical, to interleukin 1 (IL-1). Both ETAF and IL-1 have been demonstrated to be chemotactic for neutrophils and mononuclear cells in vitro. In order to demonstrate that this activity has physiological relevance we have used a simple in vivo model. The present study demonstrates that injection of high-titer ETAF or purified recombinant murine IL-1 into the mouse footpad results in an influx of neutrophils into the site with peak accumulation at 4 h. Footpad swelling also occurs with a time course roughly paralleling that of the neutrophil accumulation. Injection of control proteins failed to reproduce this phenomenon. Margination of neutrophils within blood vessels was seen within 1 h of injection of ETAF or IL-1, followed by entry into the stroma by 4 h. This suggests that chemotactic activity and not merely increased adherence or inhibition of migration is occurring. 5-10 d of daily, subcutaneous injection of ETAF on the mouse flank resulted in an infiltrate of neutrophils, and to a lesser degree, mononuclear cells in association with epidermal hyperplasia, subcutaneous fibrosis, and focal muscle necrosis in the panniculus carnosus. These findings were not seen in control sites injected with media. These findings provide direct in vivo experimental evidence suggesting a physiologic role for ETAF/IL-1 in local inflammation.

Animals↗
PubMed1986

Preferential light absorption in atheromas in vitro. Implications for laser angioplasty.

Laser angioplasty, the in situ ablation of arterial obstructions with laser radiation, has been demonstrated in animal models and early clinical trials. A problem with this technique, however, is the possibility of thermal damage to adjacent or underlying normal tissues that also absorb the radiation. Using a spectrophotometer with an integrating sphere and a specially constructed tunable-dye laser-based spectrophotometer, we evaluated the transmittance and remittance of human cadaveric atheromas and adjacent normal aorta from 250 to 1,300 nm to identify wavebands where there is preferential light absorption by atheromas. Data were analyzed by both the Kubelka-Munk formalism and a Beer's law model. Both methods indicate that atheromas absorb more than normal aorta between 420 and 530 nm. At 470 nm the average Kubelka-Munk absorption coefficient of atheromas from 10 cadavers was 54 +/- 9 cm-1 compared with 26 +/- 6 cm-1 for normal aortic specimens from seven cadavers. Yellow chromophores responsible for the atheroma absorbance were extractable with xylenes. Thin-layer chromatography and absorption spectra identified the extracted chromophores as predominantly consisting of a mix of carotenoids, which are known constituents of atheromatous lesions. Preferential absorption of blue light by carotenoids in atheromas may permit selective ablation of atheromatous obstructions with appropriate pulses of laser radiation.

Absorption↗
PubMed1986

Histologic responses of port-wine stains treated by argon, carbon dioxide, and tunable dye lasers. A preliminary report.

Although the blue-green argon laser light has been used successfully to treat port-wine stains (PWSs) for many years, it produces substantial epidermal damage. We have previously shown in normal human skin that pulsed yellow tunable dye lasers (577-nm wavelength) can cause highly selective damage to cutaneous microvessels with minimal injury to the overlying epidermis. Pulsed tunable dye lasers also produce selective vascular injury in the abnormal vessels of PWSs, with clinically apparent lightening of the lesions. Both epidermal injury and fibrosis are less severe with this laser treatment than with argon and carbon dioxide laser treatments. Clinical and histologic responses of PWSs treated by argon, CO2, and pulsed yellow dye lasers were compared and followed up for one month in three patients. Although larger and longer-term clinical trials are necessary to fully evaluate this new treatment modality, it appears that pulsed yellow laser radiation offers a more selective, less traumatic, and probably superior form of treatment for PWSs.

Adult↗
PubMed1983

Predicting psychiatric admission from an emergency room. Psychiatric, psychosocial, and methodological factors.

The determinants of psychiatric hospitalization, especially nonspecific issues, have been studied extensively. The methodological problem of correlational non-cross-validated findings are seen as contributing to our uncertainties about the critical issues involved in the decision to admit. A cross-validated multiple regression analysis of determinants of hospitalization in an inner-city municipal hospital revealed two determinants of hospitalization: severity of schizophrenic symptoms and active suicidal and/or homicidal ideation. They accounted for one third of the variance without shrinkage. Quasi-experimental designs may be the most efficient means of studying the remaining unexplained variance.

Commitment of Persons with Psychiatric Disorders↗
PubMed1980

Auditory frequency selectivity in normal and presbycusic subjects.

Auditory frequency selectivity was inferred from measurements of the detectability of tonal signals as a function of the cutoff frequency of a low-pass computer-generated noise masker. In Experiment I the effect of small changes in signal-to-noise ratio on inferred auditory frequency selectivity was studied. In Experiment II, frequency selectivity was determined for five normal-hearing subjects and four subjects with sensorineural hearing loss due to presbycusis. Critical ratios (signal-to-noise ratio at masked threshold) also were determined in Experiment II. The results of Experiment I indicate that the low-pass masking experiment provides a stable estimate of the width, but not the position, of the critical masking band. Experiment II revealed elevated critical ratios for three of the four presbycusic subjects. Some hearing-impaired subjects appeared to have normal frequency selectivity despite elevated critical ratios. Other presbycusic subjects demonstrated impaired auditory frequency selectivity. The results suggest that critical ratio and critical masking band data are free to vary independently in hearing-impaired subjects.

Auditory Threshold↗
PubMed1980

Multivariate analysis of the MMPI profiles of patients with multiple pain complaints.

The MMPI profiles of 123 male and 221 female patients with multiple pain complaints referred for psychological evaluation over a three-year period were examined using a multivariate clustering technique. Replicable subgroups were found in the patient cohorts in both the male and female samples. Multiple discriminant analysis and analysis of variance showed that the subgroups differed significantly from one another and within subgroup variation was small relative to between subgroup variation. It is suggested that pain patients are characterized by a variety of personality styles; subgroup membership may be an indication of behavior and personality dynamics which may have implications for treatment selection. Inferences as to possible treatment responses based on subgroup membership are made.

Female↗
PubMed1978

Multivariate analyses of the MMPI profiles of low back pain patients.

A multivariate clustering procedure was used to identify replicable, homogeneous MMPI profile subgroups among three independent cohorts of male (N = 233) and female (N = 315) low back pain ((LBP) patients. Three subgroups were replicated across all male cohorts and four subgroups were replicated across all female cohorts. Multiple discriminant analysis showed that for both male and female patients between-subgroup variability was significantly greater than within-subgroup variability. The results suggest that LBP patients may not be solely characterized by MMPI profiles featuring the "conversion V" configuration. Examination of the profile subgroups also suggests there may be distinct, pain-related, behavioral attributes associated with each subgroup which might have important implications for practitioners' choice of treatment modalities. Suggestions are made for research regarding the development of specific, optimal treatments for various LBP patient subgroups.

Analysis of Variance↗
PubMed1976

Proteoglycans from bovine proximal humeral articular cartilage. Structural basis for the polydispersity of proteoglycan subunit.

Polydisperse proteoglycan subunit from bovine proximal humeral articular cartilage has been separated into a series of relatively monodisperse fractions which have been chemically and physically characterized. The proteoglycan subunit species of the lowest molecular weight contains the least chondroitin sulfate and had an amino acid composition relatively low in serine and glycine and relatively high in cysteine, methionine, and aspartic acid, almost identical to that of the hyaluronic acid-binding region of proteoglycan subunit isolated by Heinegard and Hascall (Heinegard, D., and Hascall, V.C. (1974) J. Biol. Chem. 249, 4250-4256). The molecular weight of proteoglycan subunit increases in proportion to its chondroitin sulfate content. As the molecular weight and chondroitin sulfate content of proteoglycan subunit increase, there is a parallel increase in the serine and glycine contents, and a decrease in the cysteine, methionine, and aspartic acid contents of proteoglycan subunit core protein. The pattern of polydispersity observed strongly supports the concept that proteoglycan subunit core protein contains a hyaluronic acid-binding region of constant size and composition and a polysaccharide attachment region of variable length and composition, composed of repeating peptide sequences containing serine and glycine in equimolar amounts.

Amino Acids↗