Amniotic fluid squalene and fetal maturity

Gas chromatographic profiles of neutral lipids in amniotic fluid pellets were analysed for 51 specimens collected from patients in the last two months of pregnancy. The most noticeable change was a large increase in squalene relative to other components in samples at term. By expressing data as a ratio of squalene to cholesterol (S/C), it was possible to accurately predict which amniotic fluid specimens came from patients whose pregnancies were of a gestation of 40 weeks or later. Highest values for S/C and for squalene were obtained for pregnancies which were several weeks overdue.     

Alterations in T-lymphocyte subpopulations in type I diabetes. Exploration of genetic influence in identical twins

To evaluate factors influencing the alteration in subsets of T-lymphocytes, we studied 24 pairs of identical twins discordant for insulin-dependent (type I) diabetes mellitus. Subsets were assessed by monoclonal antibodies and a pure preparation of peripheral blood mononuclear cells obtained by centrifugation of heparinized whole blood with a Ficoll/Triosil gradient. In 12 pairs studied within 5 yr of diagnosis, we observed a reduction in the percentage of cells reacting with OKT8 (recognizing the CD8 antigen present on the suppressor/cytotoxic subset) (P less than .05), but a similar level was detected in their nondiabetic cotwins. In 12 pairs studied greater than 5 yr after the diagnosis and in whom the nondiabetic twin is less likely to develop diabetes, the percentage of cells reacting with OKT8 was reduced in both the diabetic (P less than .05) and the nondiabetic (P less than .01) twins. Reductions were also seen with OKT3 (recognizing the CD3 antigen present on the total T-lymphocyte population) and OKT4 (recognizing the CD4 antigen present on the helper/inducer subset), but only in the diabetic twins from the group with longer discordance. We conclude that a reduced percentage of suppressor/cytotoxic cells is associated with type I diabetes, but the reduction appears to be genetically determined. Total T-lymphocytes are also reduced but mainly in the helper/inducer subset and only in diabetic patients of long duration. Such a reduction cannot therefore be primarily genetically determined.     

Metabolic rate and thyroid status in rats fed diets of different protein-energy value: the importance of free T3

Oxygen consumption and thyroid hormone status have been investigated in relation to dietary protein and energy intake in young growing rats fed a control diet of 18% protein as well as diets containing 9 and 4.5% protein fed ad libitum and an 18% protein diet fed at a restricted intake for up to 14 days. Measurements of growth rate, food intake and oxygen consumption indicated that the rats fed a 4.5% protein diet ad libitum and those fed restricted amounts of an 18% protein diet have behaved similarly with severely arrested growth and reduced rates of oxygen consumption and food intake. However, the rats fed the 9% protein diet ad libitum differed from the control group only in terms of a reduced growth rate. Among all the rats thyroid hormone status was associated with the metabolic rate only in the case of the concentration of free L-3,3',5-triiodothyronine (T3), which was reduced in the groups fed 4.5% protein and 18% protein (restricted). Total T3 was actually increased in the rats fed 9% and 4.5% protein and unchanged in the restricted group. These differences in the concentrations of free and total T3 appeared to reflect the fact that the binding capacity for T3 increased with decreasing levels of dietary protein. It is concluded therefore that measurement of free rather than total T3 is the appropriate index of physiological thyroid status in protein-energy malnutrition, at least in the rat.     

Carboplatin dosing based on measurement of renal function — experience at the Peter MacCallum Cancer Institute

Background: Carboplatin is used in treating many types of cancer. Because renal excretion is the major variable determining the pharmacokinetics of this drug, a dosing formula based on glomerular filtration rate (GFR) has been proposed and is being increasingly used in carboplatin dosing. This method of dosing is critically dependent on accurate measurement of GFR. Aims: To report the experience at a single major oncology centre of carboplatin dosing based on GFR, and comparisons of different methods of measuring renal function for use in this dosing method. Methods: An initial group of patients (n=24) was studied where GFR was measured by Cr⁵¹EDTA clearance and compared to Tc^99mDTPA clearance, measured 24 hour urine creatinine clearance and the Cockcroft and Gault formula. The carboplatin area under the plasma concentration versus time curve (AUC) was calculated using total platinum measured in a single blood sample assayed by flameless atomic absorption spectrophotometry. A subsequent patient group (n=16) was then studied using Tc^99mDTPA clearance to measure GFR. Results: Carboplatin dosing using Cr⁵¹EDTA clearance to measure GFR was accurate (<25% difference between planned and measured AUC) in 87% of samples. Estimation of renal function using the Cockcroft and Gault formula correlated with Cr⁵¹EDTA clearance only in patients with GFR <100 mL/minute. The measured 24 hour urine creatinine clearance did not correlate with Cr⁵¹EDTA clearance. Using Tc^99mDTPA clearance to measure GFR, carboplatin dosing was accurate in 81% of samples. Across a GFR range of 42–239 mL/minute, the Cr⁵¹EDTA and Tc^99mDTPA clearances were closely correlated (r=0.98, slope of regression line=1.02). Conclusions: Carboplatin dosing using a pharmacological formula based on GFR produces accurate targeting of the carboplatin AUC. Tc^99mDTPA clearance can be used to measure GFR instead of Cr⁵¹EDTA clearance, which is both more convenient and has potential cost savings. Estimates of renal function using the Cockcroft and Gault formula or measured 24 hour creatinine clearance are insufficiently accurate to use for carboplatin dosing.     

Pinealectomy affects the diurnal variations in 2－［~（125）I］ iodomelatonin binding sites in chicken bursa of Fabricius

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