Search PubMed⌕ Search

Biomedical subjects

R L Dobson

Publications and source records attributed to R L Dobson.

13 recordsLinked to original sources
PubMed1979

Evaluation of hand cleansers.

The effect of three industrial hand cleansers on transepidermal water loss (TWL) was evaluated in groups of healthy volunteers. After 2 weeks, subjects using Baracaide averaged 47% less TWL than those using Swarfega and 35% less than with Go-Jo. In a second study in printers, the use of Baracaide decreased TWL by 20% after 2 weeks. Because it contains no volatile solvents, Baracaide may be less injurious to the barrier layer.

Dermatitis, Contact↗
PubMed1979

Unusual subepidermal bullous diseases with immunologic features of bullous pemphigoid.

Sixty-seven patients with histologic and immunologic features of bullous pemphigold (BP) were evaluated. Eleven patients had a localized blistering disease that was predominantly confined to one area of the body, most commonly the lower extremities. Two patients displayed a dapsone-responsive blistering disease that was characterized by a flexural distribution of ten to 20 1-cm or less, intensely pruitic, subepidermal bullae and linear IgA basement membrane zone deposition. Two patients had a chronic recalcitrant generalized scarring, hyperkeratotic, subepidermal blistering eruption that demonstrated serologic and direct immunofluorescence (IF) findings of BP. One patient displayed grouped small vesicles surmounted on an erythematous base; the clinical diagnosis was dermatitis herpetiformis, but direct IF examination of the biopsy specimen showed features of BP. One patient with epidermolysis bullosa acquisita had serologic and direct IF features suggestive of BP.

Adult↗
PubMed1978

Erythrokeratodermia variabilis. A family study.

Erythrokeratodermia variabilis is a rare genodermatosis; American authors have reported only four previous cases. It had been a problem to obtain a large pedigree for clinical investigation. We studied a family with 12 involved members in five generations. Symmetrically distributed migratory patches and scaling plaques are characteristic and were found to involute with a combination of keratolytic agents and topical steroids. Exacerbations of these patches and plaques were noted in our female patients during such high estrogen states as pregnancy or oral contraceptive usage.

Adult↗
PubMed1978

The tritium RBE at low-level exposure--variation with dose, dose rate, and exposure duration.

Differing values have been reported for the relative biological effectiveness (RBE) of 3H beta-radiation compared with X- and gamma-rays; but the significance of these differences has not been adequately clarified. Because large quantities of tritium are involved in nuclear energy operations, it is essential to have precise knowledge of its effectiveness compared with a "standard" radiation such as gamma-rays. This is especially true for chronic, low-level exposure since available information on protracted irradiation derives mostly from gamma-ray studies. We have approached this problem experimentally by measuring effects of low-level exposures to HTO and gamma-rays on a very sensitive mammalian system. Microscopic enumeration of oocytes in ovaries of exposed and control mice provided measurements of in vivo cell killing by constant HTO levels in body water and, for comparison, by continuous 60Co gamma-irradiation. For protracted exposure from conception to 14 days after birth, the RBE was found to be greater than 1 and to vary inversely with exposure level. At effective gamma-ray doses of 50 rad, delivered at 3.5 rad/day, the RBE was 1.6. But for 25 rad, at 1.8 rad/day, it increased to 1.9. It continued to rise as dose decreased, reaching a value of 2.5. Corrected for scattered radiation, the RBE was 2.8, close to 2.9 reported previously, but below the maximum value of 3.75 predicted by microdosimetric measurements and the theory of dual radiation action. An RBE close to 3 at low doses was not suprising. But decrease at higher doses, due to downward curvilinearity of the gamma-ray dose-response curve, was unexpected for protracted exposure. It suggested that primary oocytes in the prepubertal mouse (the cells used in this study) have limited capacity for recovery. Survival-curves for constant gamma-ray dose rates of 1 rad/min and 0.002 rad/min were therefore determined. Curvilinearity was seen in both, with greater steepness for the higher dose rate, indicating that oocytes do have some ability to recover, but that even with a dose rate only 3.2 rad/day recovery is incomplete. This in turn suggests that the observed gradient in RBE is due partly to a dose-rate effect and partly to inverse variation with dose itself, as predicted by the theory of dual radiation action for acute exposure (or incomplete recovery). Comparing protracted and shorter, 5-day exposures revealed further contrasts. At 30 rad of gamma-rays the RBE in short exposures was only 1.4, while it was 2 for protracted ones. This could be due at least in part to dose rate; it may to some degree, however, reflect difference in microdistribution of tritium atoms, greater radiobiological effect in protracted exposures resulting from 3H incorporation into especially effective sites. These systematic variations of RBE with dose, dose rate, and exposure duration help to explain some of the existing lack of agreement regarding tritium's RBE and provide a more secure basis for hazard evaluation of chronic, low-level exposure.

Animals↗
PubMed1976

Carcinogen-induced cutaneous neoplasms in nonhuman primates.

Dimethylbenzanthracene (DMBA) combined with UV light, dodecylbenzene (DDB), or both was oncogenic when applied to the skin of nonhuman primates. Ten years after the cutaneous application of DMBA and a cocarcinogen, 2 groups of rhesus monkeys (Macaca mulatta) displayed dermal melanosis, papillomas, basal cell tumors, and mesodermal sarcomas (accompanied in one case by hepatic metastasis). One group had been painted for 15 months; the other, for 6 1/2 years. Eight years after the initiation of a 4-year regimen of biweekly applications of DMBA plus a cocarcinogen, papillomas, basal cell tumors, and basosquamous cell epidermal tumors with satellite lipomas were observed in galagos (Galago crossicaudatus). The same carcinogen applied to the skin of pottos (Perodicticus potto) caused death in 6 of the 7 animals within 9 weeks. Neoplasms occurred in 17 of the 19 primates that lived longer than 9 weeks after the cutaneous application of DMBA combined with either UV light or DDB.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1975

Pemphigus and myasthenia gravis.

Various forms of true pemphigus have been reported to occur with myasthenia gravis, with and without thymoma, more frequently than can be ascribed to chance. A57-year-old woman with myasthenia gravis in remission developed pemphigus foliaceus. No roentgenologic evidence of a thymoma was present. Antinuclear antibodies caused interference with indirect immunofluorescent determination of pemphigus antibody. Indirect immunofluorescent studies showed no evidence for cross-reactivity between intercellular substance antibody and thymic components, as is found in the case of antiskeletal muscle antibodies with thymic myoid cells. The concurrence of these two diseases may involve the failure of a subgroup of thymic-dependent lymphocytes to suppress underlying autoimmune phenomena.

Animals↗