The electron microscopic features of sinus histiocytosis with massive lymphadenopathy: a study of 11 cases

Eleven cases of sinus histiocytosis with massive lymphadenopathy (SHML) involving lymph nodes were studied electron microscopically. Histiocytes were the most conspicuous element of the infiltrate. They could be divided into small and large forms, although transitions were apparent among them. Most of the small histiocytes were located in the medullary cords. The large histiocytes were predominantly seen within sinuses and were subdivided into two types on the basis of their appearance. The most distinctive feature of these histiocytes was the presence of lymphocytes, plasma cells, and neutrophils within their cytoplasm. Other cells present in the infiltrate were lymphocytes, plasma cells, and occasional neutrophils and mast cells. Blood vessels were prominent throughout. Virus particles, bacteria, and Langerhans' granules were consistently absent. No morphologic clues were provided by this study as to the etiology of this disorder.

Ammonia accumulation in platelet concentrates during storage

Newly prepared platelet concentrates (PC) and platelet poor plasma (PPP) stored at either room temperature (RT) or 4 C were analyzed for ammonia content initially, and after storage at 24, 48, and 72 hours. These studies demonstrate that ammonia rapidly accumulates in PC stored at RT. This accumulation appears to be temperature dependent, as evidenced by the observed differences in ammonia accumulation in PC stored at 4 C and RT. Whether ammonia acts as a toxic metabolite in the inhibition of platelet function and the development of the "storage lesion," which occurs in PC stored at RT, needs further clarification. Additional studies are also necessary to establish the clinical efficacy of transfusing ammonia-containing platelet concentrates into premature neonates with immature functioning livers, and perhaps into adults with severe liver disease.

Platelet abnormalities in thermal injury. Study of platelet-dense bodies stained with mepacrine

A study on platelets was done in 13 patients with severe burns during the period immediately following the thermal injury. For each patient it is possible to define a period, usually beginning around the 8th day postburn, characterised by decrease of ADP and 5-HT in the platelets and by an increase in the ATP/ADP ratio. These abnormalities strongly suggest an acquired storage pool disease. Study of the dense bodies by mepacrine labelling during this period suggests that the platelets release their contents but retain the structures labelled by mepacrine.

Experimental observations on short and long-term effects of arterial occlusion with Ivalon

Ivalon sponge has proved to be a useful embolic material, particularly when long-term or permanent occlusions are desirable. It has been stated that Ivalon is well tolerated and that it produces little if any damage to the wall or periadventitial tissues of the embolized artery. Our study demonstrates definite evidence of inflammatory reaction in the wall of the embolized arteries; these changes were seen only in the acute phase and seem to be secondary to damage of the vessel wall by the plastic material. Permanent occlusion results with disappearance of the inflammatory changes at nine months postembolization.

Pharmacodynamic interference between rifampicin and isoniazid

This study includes 30 children below the age of 3 years, distributed in three groups of 10 children each. One group received 15 mg/kg/day of rifampicin (RAMP), the other received 15 mg/kg/day of isoniazid (INH) and the third received both drugs (RAMP + INH) at the same doses. Plasma levels of RAMP and INH were determined. At the same time, some hepatic function parameters were analyzed: bilirubin, transaminases, alkaline phosphatases and prothrombin. Plasma levels of INH administered alone show significantly higher levels on the 7th day with respect to the 1st day, thus demonstrating a marked tendency towards the accumulation of successive doses. Very significant differences exist between initial and final values of transaminases in the RAMP + INH group. There are no significant differences in the other two groups. These data suggest a hepatic overload when both drugs are simultaneously administered.

Nonsurgical splenectomy

Surgical removal of the spleen is a well established procedure which is indicated for various hematologic disorders. Patients who are poor surgical risks may be considered for nonsurgical "splenectomy* using an embolization technique. This new technique should only be performed in patients who represent high surgical risk. The possible effectiveness of this procedure should be previously tested with the use of intraarterial vasopressin infusion. The following conditions should be fulfilled: (1) small emboli should be used to eliminate collateral flow; (2) the procedure should be carried out in two or three stages to minimize flank pain and the risk of massive splenic necrosis; and (3) most important, the spleen should be surgically removed as soon as the hematologic condition has improved in order to prevent splenic abscess formation. Splenic embolization was carried out in three patients with hypersplenism. One survived but was not helped by the procedure. Two died, one definitely and the other possibly as a result of the embolization. These discouraging results were reproduced in the animal laboratory where 11 of 14 animals developed severe complications, six of which were acutely fatal. The high incidence of late complications precludes non-surgical splenectomy as a routine procedure, but it can be carried out provided the spleen can be removed surgically.

Conditions for purine synthesis: did prebiotic synthesis occur at low temperatures?

The rate of polymerization of hydrogen cyanide to aminomalononitrile and the tetramer, diaminomalonodinitrile, is quadratic in the total cyanide concentration. Since the reactions form part of a plausible prebiotic purine synthesis and since they compete with hydrolysis, concentration of cyanide may have been important. This may be achieved usefully by cooling to separate out ice.