The catabolism of prostaglandins by rat skin.

The activities of NAD+-dependent 15-hydroxy prostaglandin dehydrogenase in soluble fractions of rat skin and lung were compared by using a radiochemical assay method. Tritiated prostaglandin F2 alpha was incubated with NAD+ and 120,000 g supernatant of tissue homogenate. Extracted prostaglandin substrate and reaction products were separated by t.l.c. and quantitatively determined by liquid-scintillation counting. With skin 120,000 g supernatant, 10 mM-NAD+ and an incubation time of 15 min, the mean Vmax. was 5.5 nmol of prostaglandin F2 alpha converted/s per litre of reaction mixture. With lung 120,000 g supernatant, 60 mM-NAD+ and an incubation time of 5 min, the mean Vmax. was 26.9 nmol/s per litre, demonstrating 5-fold greater dehydrogenase activity in lung per unit wet weight of tissue. However, the total wet weight of skin was about 23 times that of lung, on dissection of individual rats, indicating that the entire skin may contain 4.5 times the total 15-hydroxy prostaglandin dehydrogenase activity of the lungs. Skin may thus be an important organ of prostaglandin catabolism.     

Azathioprine in Treatment of Bullous Pemphigoid

Azathioprine was given to 11 patients with pemphigoid who had been on long-term maintenance therapy with prednisone or prednisolone. In nine of these prednisone therapy was withdrawn and all were maintained symptom-free on azathioprine alone, while in two the dose of prednisone was considerably reduced. One patient who had never received corticosteroids was controlled by azathioprine alone during the initial acute phase of the illness. Since azathioprine acts slowly, it is recommended that corticosteroids should be used together with azathioprine during the acute stage. Thus azathioprine is valuable in long-term management of pemphigoid, particularly in patients showing corticosteroid toxicity or in whom the minimum maintenance dose is dangerously high.     

Globin gene switching: A paradigm or what?

The delineation of the beta-globin locus control region has led to a new understanding of the developmental regulation of the beta-globin gene cluster. It now seems that globin gene switching is effected through the sequential and mutually exclusive interaction of the locus control region with the embryonic, fetal and adult stage specific globin genes.     

Relapse rate and long-term management of plaque psoriasis after treatment with photochemotherapy and dithranol.

The relapse rate of plaque psoriasis after initial clearing with the "Ingram" dithranol regimen or photochemotherapy was comparable when no maintenance treatment was given. It was estimated that psoriasis recurs to half of its pretreatment extent after about six months in half the patients. Maintenance treatment with photochemotherapy once a week or once every three weeks was useful in reducing the relapse rate. This study failed to show any statistical difference in relapse rates between these two maintenance schedules. If this finding turns out to be true over longer periods of study the maintenance schedule entailing treatment once every three weeks with its lower cumulative dose of long-wave ultraviolet light will clearly be preferable. The psoriasis in most patients was under better overall control with maintenance treatment than with intermittant clearing courses given when the extent of the psoriasis had become unacceptable to them. There was, however, a group of roughly one-fifth of patients who remained in satisfactory remission for over 16 months after initial clearing. Regular maintenance treatment was unnecessary in them. Much more information is needed on response to treatment in subgroups of patients to permit recognition from the start of which patients are likely to have long remission and which are not.