Radiopharmacological evaluation in dogs of a new renal function agent.

The hydrophilic penta-anionic complex [Technetium (Carboxymethylisocyanide)6]-5, [Tc(CNCH2COO-)6]-5 (Tc-CAMI) was synthesized to evaluate its potential as a renal function imaging agent. The compound contains six distally arranged carboxyl groups that can act as substrates for the organic acid receptor of the renal cell to effect tubular secretion of this agent. Dynamic gamma-camera imaging of 99mTc-CAMI was performed in normal dogs to compare its bio-distribution and pharmacokinetics with those of proven tubular secretion (99mTc-MAG3) and globular filtration (99mTc-DTPA) agents. The relative difference between the observed mean renal transit times (MRTT) of 99mTc-CAMI and 99mTc-MAG3 was 0.15 compared with 1.24 for 99mTc-CAMI and 99mTc-DTPA. Pathological models of obstructive uropathy, renal arterial stenosis and renal denervation were produced in the same animals to demonstrate the diagnostic potential of the agent. These experiments and data showing that probenecid competes with 99mTc-CAMI for renal transport indicate that this compound functions as a tubular secretion agent and may be useful for monitoring renal function in various disease states.

A study of nasal respiratory resistance and craniofacial dimensions in white and West Indian black children.

Two studies have shown that there are morphologic differences in the nasopharynx between the major racial groups. This investigation was conducted to see whether these morphologic differences affected nasal respiration. Twenty-two West Indian and 24 white children (mean age of 13 years 11 months) were studied to examine the relationship between nasorespiratory function and nasopharyngeal and dentofacial structure. The nasorespiratory function was measured in terms of nasal respiratory resistance, NRR, (Pascals/cm3 per second), both by anterior and posterior methods, with a computerized rhinomanometer. Nasopharyngeal structure was described in terms of cephalometric variables. The West Indian cephalometric profile generally conformed to its existing description in the literature including prognathic jaws and bimaxillary proclination; in addition, the West Indians were found to have a greater bony nasopharyngeal width (posterior nasal spine-basion) and shallower nasopharyngeal roof angle (posterior nasal spine-hormion-basion). All rhinomanometric measurements were significantly lower in the West Indian group, especially when posterior rhinomanometry was used. The correlation coefficients between the cephalometric and the rhinomanometric measurements were statistically significant but low. In addition, the measure of mandibular prognathism (angle SNB) was also found to be significantly correlated with the nasorespiratory resistance.

Radiopharmacological studies of 99mTc-CPI: experience with isolated rat atrial tissue.

Extraction, washout and chemical integrity of technetium(I) hexakis (2-carbomethoxy-2-isocyano propane), (99mTc-CPI) were evaluated in isolated contractile rat atrial tissue. 99mTc-CPI accumulated linearly over time at 32 degrees C with uptakes that were both concentration dependent and temperature sensitive. Uptake rates also increased with contractile strength, indicating a dependence of retention on metabolic status of the tissue. Retention indices showed that percent washout of 99mTc-CPI was much slower than control studies with 99mTcO4. HPLC analysis of retained radioactive products in atrial tissue showed most of the activity present as the 99mTc-CPI complex (75%). These observations in isolated rat atrial tissue help explain the interspecies differences in biodistribution of 99mTc-CPI and support the membrane potential dependent model for uptake and retention of technetium isonitrile complexes.