[Reversible computed tomographic changes following brain tumor irradiation induced by the "early-delayed reaction" after radiation]

We analyzed the incidence, timing and appearance of reversible CT findings in 55 patients undergoing radiation therapy (dose 60 Gy) for brain tumors. Three patients had "early delayed reactions" within three months of irradiation. CT studies showed increased size of the central zone of necrosis with contrast enhancement in the form of rings or garlands. Differentiation between these findings and recurrence of tumor was possible only through follow-up studies.

[Comparison of the computed tomographic changes and the clinical course following the irradiation of intracranial tumors and metastases]

The authors compared the clinical courses and the CT courses recorded at the same time in patients with primary or secondary cerebral tumors. 69 patients improved their neurologic state under external radiotherapy, 35 patients remained unchanged, and 8 patients had a deteriorated condition. The changes in computed tomography and the modifications of the clinical state of patients corresponded only in 55% of all cases. The reasons are discussed. Some patients suffered from fatigue and weak concentration about three months after the end of radiotherapy, in some cases even the neurologic state was deteriorated. These manifestations known as "early delayed reaction" were reversible.

[Pharmacokinetic and clinical studies with sisomicin in paediatrics (author's transl)]

Pharmakokinetic and clinical investigations were carried out with sisomicin, one of the newer aminoglycoside antibiotics, in 40 children aged from seven days to ten years. Serum concentrations were determined in 35 children 1/2, 1, 2, 4 and 6 hours after i. m. injection of 1.0 mg sisomicin/kg body weight. The average peak serum levels were 2.48 mg/l in children under three months and 3.58 mg/l in children between seven months and ten years. Renal elimination in newborns is delayed in comparison to older infants and children; the distribution volume of the central compartment diminishes with increasing age. The effect of these two counteracting tendencies is that renal clearance remains constant in the age groups investigated, however the frequency of drug administration must be adjusted according to age. During an average treatment period of ten days adequate serum concentrations between 3.1 mg/l and 6.2 mg/l one hour after injection could be achieved with dosages adjusted to age and body weight. Clinical results were good: 18 out of 20 children could be cured clinically, and 20 out of 21 isolated infectious agents were eliminated. There were no problems in local and systemic tolerance.

Binding of sisomicin and streptomycin to human albumin

The aminoglycosides of the kanamycin and neomycin series are displaced from their protein binding by very low Ca++ ion concentrations, whereas streptomycin is displaced only by very high Ca++ ion concentrations. For streptomycin, therefore, the binding mechanism must differ from that for the other aminoglycosides. The displacing reaction cannot be described by the law of mass action, combining the binding equations. Several possible reasons, such as complex formation and changes in the conformation of albumin, are discussed. Complex formation between sisomicin and the lanthanide ion Nd+++, which has the same ionic radius as the Ca++ ion, could be excluded by recording the difference absorption spectrum. The displacement of the aminoglycosides from their protein binding by Ca++ ions (as well as the pH dependence of the protein binding) suggests that ionic bonds are involved in the interactions between aminoglycosides and serum proteins.