Effects of methylphenidate and d-amphetamine on timing in the rat

Rats were trained to press a lever for food pellets provided according to a fixed interval 60-sec schedule of reinforcement. Probe trials (peak trials) assessed responding over two-min periods with no pellet delivered. The low rates of responding found early and late in probe trials were increased by methylphenidate and 1.0 mg/kg d-amphetamine (rate-dependent effect). Further, the mean time of responding (peak time) was shortened for both drugs (timing effect).     

Improved estimates of discordance ratios in twin studies

In the study of monozygotic twins relative to disease and risk factors, particular interest focuses on the subset who are discordant for some suspected risk factor (for example, smoking), since such twins constitute a natural case-control pair. In such studies, questionnaires designed to identify the status of all twin pairs are sometimes error prone and can yield misleading estimates of the concordance-discordance ratios. Greater efforts to verify the characteristics of apparently discordant pairs than to verify those of apparently concordant pairs can result in the 'unequal ascertainment' fallacy. Using the results of a questionnaire with known error rates and the 'apparent' frequencies yielded, we present unbiased, maximum likelihood estimates of the 'true' proportions of concordant and discordant pairs. concordant and discordant pairs. We also present approximate covariances among these estimates.     

Aspiration drainage of splenic abscesses

The successful use of guided percutaneous needle aspiration in the management of four patients with solitary splenic abscess is described. Two patients had needle aspiration alone and two patients, with large splenic abscesses, had drainage tubes inserted. The procedures were well tolerated and allowed rapid microbiological diagnosis with selection of appropriate antibiotic therapy. The techniques were useful in patients felt to be poor anaesthetic risks, and the complications of splenectomy were avoided.     

Breast reconstruction by tissue expansion for congenital and burn deformities

We have used tissue expanders to treat 10 patients with breast deformities, 2 the result of burns and 8 congenital in origin. The expanders are placed in the subglandular plane and expanded incrementally until the desired amount of growth is obtained. In patients with congenital deformities, the desired size of the reconstructed breast (implant size) is determined during the expansion phase. Reconstructions of the nipple-areola complex are done either at the time of the exchange or as separate procedures. Patients with burn deformities present a variety of problems not seen with the congenital deformities. The expander is placed in the subglandular plane and filled to the desired volume. We have noted a marked permanent softening of the scar and grafts encasing the breast, which persists after the expander is removed and the breast reconstructed. The interval between expansion and definitive reconstruction is delayed for several months to allow scar softening to take place. If the parenchyma is not burned and pedicle tissue is not required, the expander can be deflated and the skin coverage observed to determine if it will remain soft. If it does, the expander can be removed and the breast reconstructed. In patients who require pedicle coverage in the reconstruction and who have unburned scar surrounding the breast, massive overexpansion is carried out. The pedicle skin is used to resurface the breast after removal of the appropriate areas of scar and skin grafts. In all burned patients, the inframammary fold must be reconstructed if the breast is to be protuberant. The nipple-areola complex also requires reconstruction. To date there has been great acceptance by patients with both congenital and burn deformities; however, we believe that tissue expansion techniques offer possibilities that have not as yet been fully explored.     

Synthesis and biological evaluation of technetium-99m MAG3 as a hippuran replacement

A new technetium-chelating agent based on a triamide monomercaptide tetradentate set of donor groups, mercaptoacetylglycylglycylglycine (MAG3), was synthesized and evaluated. Chelation with 99mTc resulted in a single radiochemical product as expected. Studies in mice of [99mTc]MAG3 indicated excretion rates faster than omicron-iodohippurate (OIH) both in normal and in probenecid treated animals. Specificity for renal excretion was essentially complete. Clearance studies in rats resulted in 2.84 ml/min/100 g for [99mTc]MAG3, 2.17 for OIH, and 1.29 for [125I]iothalamate. Extraction efficiencies were 85% for [99mTc]MAG3, 69% for OIH and 39% for [125I]iothalamate. Probenicid depressed the clearance both of [99mTc]MAG3 and OIH at 25 and 50 mg/kg/hr, but to a greater extent with [99mTc]MAG3. The greater effect is offset, however, by the larger fraction secreted by the renal tubular cells. The animal results suggest that [99mTc]MAG3 may be a useful alternative to [131I]OIH.     

Comparative study of 3 therapeutic methods for Pouteau Colles' fracture. Apropos of 97 cases

Results of three therapeutic modalities used for the treatment of a homogeneous series of patients with a Pouteau Colles fracture are analyzed. Orthopedic treatment provided deceiving results. Pinning was, on the contrary, very effective, intrafocal pinning with immediate mobilization of the wrist appearing perfectly effective. Few complications were reported in contrast to plastered immobilizations. Good results were obtained in 80% of cases and functional recovery was rapid, indicating that this method represents undoubted progress when compared with conventional therapies.