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Biomedical subjects

L R Klein

Publications and source records attributed to L R Klein.

16 recordsLinked to original sources

Photoexacerbation of cutaneous lupus erythematosus due to ultraviolet A emissions from a photocopier.

This report describes a woman with systemic lupus erythematosus (LE) who worked as a photocopy technician and developed cutaneous LE of the hands, neck, face, and chest. Her skin lesions improved when she discontinued her employment. Testing of several photocopy devices showed emission of small quantities of ultraviolet A (UVA), but no UVB. Phototesting of the patient with UVA and UVB induced skin lesions that were clinically and histopathologically consistent with LE. Thus, the action spectrum of cutaneous LE may be within the UVB range, the UVA range, or both ranges of the solar spectrum, and repeated exposure to short bursts of light may induce clinical disease. This case suggests that occupational sources of UV light should be considered as possible exacerbating factors in LE.

Biopsy

Immunolabelling by a newt retinal pigment epithelium antibody during retinal development and regeneration.

The binding of RPE-1, a mouse monoclonal antibody selective for newt retinal pigment epithelium, was followed in eyes undergoing embryonic development and retinal regeneration. Using the indirect immunofluorescence technique on frozen sections, we observed bright and continuous labelling exclusively in the retinal pigment epithelium (RPE) of normal adult newts, but labelling became diminished near the ora serrata region and stopped abruptly at the ciliary margin. During development, labelling was not detected in the retinal pigment epithelium (RPE) until the formation of photoreceptor outer segments and was not observed in any other ocular tissue. There was no correlation between the appearance of pigment in retinal pigment epithelial cells and their labelling with the RPE-1 antibody. Furthermore, albino salamander embryos showed the same pattern of labelling with RPE-1 as that seen in age-matched pigmented animals. During retinal regeneration, RPE cells were labelled less intensely, but heavy labelling was observed in the newly formed retinal cells. With time, labelling in regenerated retina receded, so that by the end of regeneration, labelling by RPE-1 was once more restricted to the RPE cells. The identification of RPE-1 as a marker for postmitotic retinal neurons about to undergo differentiation provides a promising approach for further studies of regeneration with the help of molecular tools.

Albinism

Cutaneous mast cell quantity in pruritic and nonpruritic hemodialysis patients.

Pruritus remains a significant complication of end-stage renal disease. Its cause in hemodialysis patients is not known. It has been postulated that increased numbers of mast cells occur in these patients and may account for the presence of pruritus. Our objective was to determine if there is a difference in the number of cutaneous mast cells between pruritic and nonpruritic patients. A 3-mm punch biopsy specimen was obtained from pruritic (n = 7) and nonpruritic (n = 6) hemodialysis patients. We observed no significant difference in the quantity of cutaneous mast cells in pruritic and nonpruritic hemodialysis patients. We conclude that the etiology of pruritus in hemodialysis patients is not related to an increase in the number of cutaneous mast cells.

Aged

Comparison of collagen degradation and synthesis in the peripheral and central areas of experimental corneal grafts.

The distribution of collagen degradation and synthesis (turnover) between the central and peripheral areas of clear corneal allografts was determined, following transplantation of 6-mm [3H]proline-labelled corneal buttons from extensively pre-labelled, young rabbits into 13 nonradioactive mature rabbits. Control, contralateral 6-mm corneal buttons of each radioactive pair were frozen at -70 degrees C after being trephined into a central 3-mm button and a peripheral ring of cornea. The grafts were removed 10-100 days after the operation and trephined similarly to the paired controls. The central and peripheral areas of the graft and control corneal buttons were analysed separately for total hydroxyproline and radioactivity. A significant degradation of old collagen (as seen by the loss of total radioactivity) occurred early in both the central (19.4 +/- 6.1%) and peripheral (12.3 +/- 7.5%) areas of the grafted corneas, compared to the corresponding areas of the contralateral controls. A significant increase in new, non-radioactive collagen occurred in both the central (22.0 +/- 7.6%) and peripheral areas (30.6 +/- 6.1%); however, a significant net increase in total collagen occurred only in the peripheral area (18.3 +/- 11.4). Loss of original (old) collagen was significantly greater in the central area than in the peripheral area; whereas, the increase in new collagen was significantly greater in the peripheral area than the central area, accounting for a significant increase in total collagen. There was no correlation in collagen turnover with time after surgery. Collagen turnover occurs acutely throughout the clear corneal graft and thereafter is stable.

Animals

Effects on bone of vascular interruption. Turnover and morphology in isotope-prelabelled rats.

The effects of bone devascularization were evaluated histologically and metabolically in rats prelabelled with 45Ca, 3H-tetracycline and 3H-proline by quantifying cortical bone resorption and formation. The interruption of blood supply to bone without invading its integrity resulted in a marked increase in bone turnover (resorption and formation) during the first and second months. The stimulated increase in bone resorption and formation did not affect the resultant mass of collagen and calcium. Thus, the increase in bone resorption was compensated by an equivalent increase in bone formation.

Animals

Analysis of procainamide hydrochloride and acecainide hydrochloride in rat feed.

An extraction and GLC assay procedure was developed for quantitation of procainamide hydrochloride and acecainide hydrochloride in rat feed. 4-Amino-N-[2-(dipropylamino)ethyl]benzamide hydrochloride was synthesized and utilized as an internal standard. The assay has good precision and accuracy and was used to establish the stability of acecainide hydrochloride and procainamide hydrochloride in rat feed.

Acecainide