D.W.K. Cotton

Lichenoid Eruption Following Penicillamine

The phenomenon of lichenoid eruptions following medication with anti-malarial, anti-arthritis and antibacterial medication is well documented in the literature. We report here the first case to be des

Hexokinase, glucose‐6‐phosphate dehydrogenase, and malate dehydrogenase in the isolated sweat glands of normal and atopic subjects

The kinetics of the enzymes hexokinase, glucose‐6‐phosphate dehydrogenase, and malate dehydrogenase have been determined and compared in pooled isolated sweat glands from normal and atopic subjects. No significant differences could be detected in the kinetic constants Vmax and Km for any of the substrates or co‐factors studied in the two groups of subjects.

Psoriatic therapeutics and glucose-6-phosphate dehydrogenase.

SummaryThe inhibitory effects of various agents on the enzyme glucose-6-phosphate dehydrogenase have been studied in vitro. Stress is laid on the calculation of kinetic parameters such as trueKI values. The most active inhibitor was methotrexate, closely followed by cGMP. The increase in inhibitory activity after incubation of methotrexate with liver slices is discussed.ZusammenfassungDie Hemmungseffekte verschiedener antipsoriatischer Agentien auf das Enzym Glucose-6-Phosphat Dehydrogenase wurden in vitro untersucht. Die Berechnung kinetischer Parameter, insbesondere der wahrenKI-Werte, wird hervorgehoben. Der aktivste Hemmstoff war Methotrexat, gefolgt von cGMP. Die Erhöhung der Hemmwirksamkeit nach Inkubation von Methotrexat mit Leberschnitten wird diskutiert.

Fourier analysis of thermal sweating

A number of reports exist in the literature describing cyclic aspects of human eccrine thermal sweating (Rothman, 1954). Dependent on the technique employed, various frequencies have been observed. These range from monthly cycles associated with menstruation (Taylor et al.., 1969) through diurnal cycles (Spruit, 1971) down to cycles of approximately 10 H^. Cycles of about i H^ have been observed using water vapour analysers (Kuypers & Cotton, 1972) and these frequencies are similar to those reported for GSR (galvanic skin reflex or response) cycles. The I H^ cycles are the most obvious in thermal sweating recorded with water vapotir analyser systems such as the Meeco and are probably the expression of the activation of the autonomic nerve supply of the gland. The higher frequencies may be due to myoepithelial cell contractions (Nicolaides & Sivadjian, 1972). Since these various frequencies might be expected to represent distinct processes within the total response of thermal sweating, it follows that disorders of sweating might be due to disturbances in any one or combination of these. Consequently it would be very informative to be able to study these frequencies independently. The standard method for selecting individual frequencies from a band of superimposed frequencies is Fourier analysis. The method is adequately described in a number of standard texts and various computer programs have been constructed. We have, therefore, performed manual Fourier analysis on 28 min of continuous sweat record (Fig. i) and have also done this on-line using a Tektronix digital processing oscilloscope (DPO). The Fourier analysis calculations are extremely tedious to do by hand but are simple with on-line computation. The technique permits the identification of individual frequencies as well as their quantification. We are now applying the technique to normal subjects under various environmental conditions to establish normal ranges and will follow this with studies on various disorders, such as atopy, in which there is reason to suspect a central or peripheral disturbance in the sweating process.

Horizontal Distribution of Three Dehydrogenases in the Cow Snout Epidermis

A technique is described for quantifying enzyme activities in the various layers of the epidermis of the cow snout. Values for glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and lactate dehydrogenase are reported. In general, the amount of each enzyme is largest in the basal layers and diminished towards the stratum corneum. The exception was G6PD whose highest peak of activity was in the region of the stratum spinosum.

Electron microscopy of the sweat glands from the hairy skin of the beagle

Recently Bell & Montagna (1972) published the results of a light histochemical study of sweat glands in the hairy skin of horses and dogs. They found that there was no demonstrable inncrvation of these glands in the dog. We have previously reported stimulation ofthe sweat glands on the hairy surface of the beagle by hypothalamic (Cotton, van Hasselt & Bergcrs, 1975) and peripheral nerve stimulation (Cotton & van Hasselt, 1972) but the stimulus levels were so high that we believe the effects to be unphysiological and secondary. The only effective physiological stimulus that we have found is copulation (Cotton et ah, 1975). Other authors have found that the kangaroo sweats during physical stress in a treadmill but not in response to heat (Dawson, Robertshow & Taylor, 1974)The data in the literature indicate that the sweat glands on the hairy surface ofthe dog are apocrine (Iwabuchi, 1967) and it is well known that the development of human apocrine glands is associated with sexual maturity (Zelickson, 1967). On the basis of these observations we have tentatively suggested (Cotton et ah, 1975) that these glands may have a pheromone (Mykytowycz & Goodrich, 1974) function in the dog. Since the structure of these glands has only been studied at the light histological level, we thought that it might be of interest to examine them under the electron microscope. We have sectioned a number of sweat glands obtained from the hairy skin of the dog and the following morphological details are apparent. In no section did we observe any nerve ending although these were readily discernable in human eccrine and dog foot pad preparations. Only two types of cells were visible, myoepithelial cells and secretory cells, containing many inclusions and bordered with microvilli (Cotton et al., 1975). The secretory cells contained the atypical mitochondria with amorphous matrix as described by Zelickson (1967) and sweat glands obtained from areas which had been stimulated to sweat by local injections of acetylcholine showed extended apical regions free of microvilli and inclusions. Consequently we conclude that these glands are apocrine and lack direct innervation. These conclusions, although not providing direct proof, are in accordance with the idea that the glands may serve a social communication function in addition to any as yet unclear, thermal regulation function.

Glucose-6-Phosphate Dehydrogenase in the Blood of Psoriatics, and the Effects of Methotrexate

The kinetic constants of glucose-6-phosphate dehydrogenase from the blood of psoriatics with and without methotrexate therapy have been determined. The constants were also determined in the blood of normal subjects and subjects suffering from atopic dermatitis and mycosis fungoides. No significant differences were found between subjects not receiving methotrexate. The subjects receiving methotrexate showed markedly increased Km values for both glucose-6-phosphate and NADP under the conditions used. The results are discussed in relation to psoriasis and its therapy.

ATROPINE AND SWEATING

BEUTNER, E.H., CHORZELSKI, T.P., HALE, W.L. & PETREUSEWICZ, I. (1968) Auto-immunity in a case vi-ith concurrent myasthenia gravis and pemphigus erythematosus. Journal of the American Medical Association, 203, 845. CHANG, C M . , DENG, J-S. , LU, Y C . & NG, K-Y. (1973) Pemphigus vulgaris—a skin manifestation of epidermoid carcinoma. Journal of the Formosan Medical Association, 71, 50. KouGH, E.H. & BARNES, W.T. (1964) Thymoma associated with erythroid aplasia, bullous skin eruption and the lupus erythematosus cell phenomenon. Annals of Internal Medicine, 61, 308. PECK, S.M., OSSERMAN, K.E., WEINER, L.B., LEFKOVITS, A. & OSSERMAN, R.S. (1968) Studies in bullous diseases. New England Journal of Aledicine, 279, 951. SAIKIA, N.K. (1972) Extraction of pemphigus antibodies from a lymphoid neoplasm and its possible relationship to pemphigus vulgaris. British Journal of Dermatology, 86, 411. SAIKIA, N.K. & MACCONNELL, L.E.S. (1973) Senear-Usher syndrome and internal malignancy. British Journal of Dermatology, 87, i. VETTERS, J.M., SAIKIA, N.K., WOOD, J. & SIMPSON, J.A. (1973) Pemphigus vulgaris and myasthenia gravis. British Journal of Dermatology, In press. WHITTINGHAM, S. & MACKAY, l.R. (1971) The pemphigus antibody and immunopathies affecting the thymus. British Journal of Dermatology, S4, t.

Screening for 6-Phosphogluconate Dehydrogenase Abnormalities in the Blood of Dermatological Patients

The results of screening for 6-phosphogluconate dehydrogenase abnormalities in the blood of dermatological patients are reported. No differences were found between controls, psoriatics, psoriatics receiving methotrexate and a group of mixed patients. The results are discussed in relation to the effects of methotrexate on glucose-6-phosphate dehydrogenase.

Nature of the Sweat Glands in the Hairy Skin of the Beagle

The local pharmacology, the thermal response and the response to hypothalamic stimulation of sweat glands of the hairy surface of the beagle are described. The results, together with those of electron-microscopic examinations, support the idea that these sweat glands are apocrine and are not directly innervated. No clear relationship with thermoregulation could be found and a pheromonal function is tentatively suggested.