Ureteral Stones Clinical Guidelines Panel summary report on the management of ureteral calculi. The American Urological Association

PURPOSE: The American Urological Association convened the Ureteral Stones Clinical Guidelines Panel to analyze the literature regarding available methods for treating ureteral calculi and to make practice policy recommendations based on the treatment outcomes data. MATERIALS AND METHODS: The panel searched the MEDLINE data base for all articles related to ureteral calculi published from 1966 to January 1996. Outcomes data were extracted from articles accepted after panel review. The data were then meta-analyzed to produce outcome estimates for alternative treatments of ureteral calculi. RESULTS: The data indicate that up to 98% of stones less than 0.5 cm. in diameter, especially in the distal ureter, will pass spontaneously. Shock wave lithotripsy is recommended as first line treatment for most patients with stones 1 cm. or less in the proximal ureter. Shock wave lithotripsy and ureteroscopy are acceptable treatment choices for stones 1 cm. or less in the distal ureter. CONCLUSIONS: Most ureteral stones will pass spontaneously. Those that do not can be removed by either shock wave lithotripsy or ureteroscopy. Traditional blind basket extraction, without fluoroscopic control and guide wires, is not recommended. Open surgery is appropriate as a salvage procedure or in certain unusual circumstances.     

Open-channel block of N-methyl-D-aspartate (NMDA) responses by memantine: therapeutic advantage against NMDA receptor-mediated neurotoxicity

Excessive activation of NMDA receptors is thought to mediate the calcium-dependent neurotoxicity associated with hypoxic-ischemic brain injury, trauma, epilepsy, and several neurodegenerative diseases. For this reason, various NMDA antagonists have been investigated for their therapeutic potential in these diseases, but heretofore none have proven to be both effective and safe. In the present study, memantine, an adamantane derivative similar to the antiviral drug amantadine, is shown to block the channels activated by NMDA receptor stimulation. From whole-cell and single-channel recording experiments, the mechanism of action of memantine is deduced to be open-channel block, similar to MK-801; however, unlike MK-801, memantine is well tolerated clinically. Compared to MK-801, memantine's safety may be related to its faster kinetics of action with rapid blocking and unblocking rates at low micromolar concentrations. Furthermore, at these levels memantine is an uncompetitive antagonist and should theoretically allow near-normal physiological NMDA activity throughout the brain even in the face of pathologically high focal concentrations of glutamate. These pharmacological properties confer upon memantine a therapeutic advantage against NMDA receptor-mediated neurotoxicity with few side effects compared with other organic NMDA open-channel blockers. Moreover, memantine is increasingly effective against escalating levels of glutamate, such as those observed during a stroke. Low micromolar concentrations of memantine, levels known to be tolerated by patients receiving the drug for the treatment of Parkinson's disease, prevent NMDA receptor-mediated neurotoxicity in cultures of rat cortical and retinal ganglion cell neurons; memantine also appears to be both safe and effective in a rat stroke model. These results suggest that memantine has considerable therapeutic potential for the myriad of clinical entities associated with NMDA receptor-mediated neurotoxicity.     

The effects of smoking on bone mass and the rates of bone loss among elderly Japanese-American men

Bone density and bone loss rates were examined among Japanese-American men categorized as current cigarette smokers, past smokers, and nonsmokers. The design included a retrospective study of smoking and bone density and a prospective study of current smoking and bone loss rates. The mean length of follow-up was 5 years; the setting was the island of Oahu. The subjects included 1303 men in the Hawaii Osteoporosis Study, 51-82 years old at their initial examination. Twenty percent were current smokers, 45% past smokers, and 35% had never smoked. Their bone density was measured at the distal and proximal radius and calcaneus using single photon absorptiometry. Compared with never smokers, current and past smokers had significantly lower bone density, especially in the predominantly cancellous calcaneus (4.8 and 4.3% lower, respectively) and partially trabecular distal radius (1.8 and 3.3% lower, respectively). The magnitude of the smoking effect was linked strongly to the duration of smoking and also to the number of cigarettes smoked. Bone loss rates subsequent to the initial measurement were greater in the current smokers than the never smokers (20.5, 27.2, and 9.7% greater at the calcaneus, distal, and proximal radius, respectively) but the differences did not achieve significance. Smokers of more than one pack per day had 32.0, 77.6, and 30.7% greater loss rates than never smokers in these same sites; the difference achieved significance at the distal radius. The results from the distal radius suggest that these smokers may increase their fracture risk 10-30% per decade of smoking. The adverse effects of smoking appeared to be greater in cancellous than cortical bone.     

Effect of pregnancy on maternal oxygen saturation values: use of reflectance pulse oximetry during pregnancy

Our objective was to evaluate the usefulness of pulse oximetry monitoring in a large population of pregnant patients. We designed our study to measure pulse oximetry saturation in a cross section of 952 obstetric inpatients and outpatients. A group of 366 patients identified as normal were compared with abnormal subgroups. A subgroup of 64 patients with saturation measurements less than 96% were further evaluated. Our results indicated that oxygen saturation values did not change appreciably during the course of pregnancy in normal patients. Hypoxemia (saturation measurement less than 96%) was associated with smoking, and hypoxemia with preterm labor occurred more frequently in patients who smoked. Obesity and magnesium sulfate use appeared to be synergistic in the presence of hypoxemia. We concluded that the routine use of pulse oximetry during pregnancy may not be justified. Smoking, obesity, and magnesium sulfate use have some effect on oximetry in pregnant patients.     

Comparison of abrasion model differences in heavy ion fragmentation: optical versus geometric models

Using an abrasion-ablation collision model, which includes contributions from frictional-spectator interactions and electromagnetic dissociation, analyses of the sensitivities of predicted fragmentation cross sections to the choice of a particular abrasion formalism are made using both geometric and optical potential abrasion models. Most cross section differences obtained using the two abrasion models are less than the present experimental uncertainties, suggesting that either abrasion model is suitable for estimating isotopic and elemental fragment distributions.     

Cerebral complications of murine monoclonal CD3 antibody (OKT3): CT and MR findings

Treatment of acute renal allograft rejection with mouse monoclonal antibody (OKT3) is associated with systemic and neurologic side effects. We describe cerebral abnormalities in a 13-year-old boy with steroid-resistant renal allograft rejection. After treatment with OKT3, an acute neurologic syndrome developed, including seizures, lethargy, and decreased mental function. CT and MR imaging revealed confluent cerebral lesions at the corticomedullary junction. Contrast-enhanced MR images showed patchy enhancement, indicating blood-brain barrier dysfunction. The diagnosis of OKT3-induced encephalopathy with cerebral edema and capillary leak syndrome was made. Although CT and MR findings are nonspecific, neuroradiologists should be aware of this condition in transplant patients treated with OKT3.     

In vitro metabolic N- and C-oxidation of phenanthridine

In order to compare an acceleromyograph (TOF-Guard) with a mechanomyograph (Grass FT03), the dose-response relationship of rocuronium was simultaneously determined in both arms of 15 children aged 3-11 years during anaesthesia with thiopentone, alfentanil and nitrous oxide. Three subgroups of five children received rocuronium 120, 180 or 240 micrograms.kg-1 randomly. The effective doses to produce 50% and 95% depression of the first twitch of the train-of-four determined by acceleromyography were 206 and 337 micrograms.kg-1, respectively, while these values determined by mechanomyography were 151 and 331 micrograms.kg-1, respectively. The dose-response curve obtained by acceleromyography was steeper and shifted to the right compared with that obtained by mechanomyography (p < 0.0001). The difference between the effective dose producing 50% twitch depression determined by the two devices was highly significant (p < 0.0001). In 13 out of 15 children, the acceleromyograph control train-of-four ratio was significantly greater than unity. Although there was a good correlation (r = 0.85) between simultaneous pairs of measurements of neuromuscular block, the acceleromyograph exhibited a bias of -25% relative to the mechanomyograph with wide limits of agreement (-62 to +12%). We conclude that acceleromyographic and mechanomyographic measurements should not be used interchangeably when determining the potency of muscle relaxants.