Two classes of spontaneous GABA-mediated miniature synaptic currents in cultured rat hippocampal neurons.

Amplitude and time course of spontaneous gamma-aminobutyric acid (GABA)-mediated miniature postsynaptic currents (MPSCs), recorded in cultured embryonic hippocampal neurons in presence of either tetrodotoxin (TTX) or increased external [Mg2+/Ca2+] ratio, revealed that they form two classes. The distribution of the most commonly recorded MPSCs was skewed both in terms of peak amplitude and rise-time (skew-MPSCs, mode: 70-120 pS). Another, less frequent class (mode: 1-3 nS) formed bell-shaped (bell-MPSCs) amplitude and rise-time distributions. MPSC initial slope did not correlate with rise time, indicating that smaller MPSCs were not electrotonically attenuated. Bell-MPSCs did not result from the integration of skew-MPSCs and both classes appeared to be composed of subunits.     

Intra-arterial chemotherapy for head and neck cancer. An update on the totally implantable infusion pump

Intra-arterial chemotherapy for the treatment of localized malignant neoplasms in the head and neck is an appealing approach for several reasons. Perhaps the most important is the possibility of obtaining a regional advantage such that an increased drug concentration is delivered systemically. The patient may, therefore, be spared systemic toxicity. We report our accumulated experience using a totally implantable infusion pump in 37 patients. A total of 42 pumps were implanted: 28 single-catheter pumps and 14 dual-catheter pumps. Radionuclide imaging demonstrated total perfusion of the tumor in all patients. A combination of cisplatin (50 to 100 mg/m2) and floxuridine (0.01 to 0.045 mg/kg/d) was used to treat 26 patients. For these heavily pretreated patients, we observed a 43% complete and partial response rate in the subgroup of patients with squamous cell carcinoma. These results are comparable with those reported for these drugs administered systemically and for other drug combinations tested in the treatment of recurrence disease.     

Haemodynamic assessment of the femoropopliteal segment: comparison of pressure and Doppler methods using ROC curve analysis

Combined aorto-iliac and femoropopliteal vascular disease remains a problem in vascular surgery. Arteriography does not provide information on the relative contributions of the two lesions to the presenting symptoms. Aorto-iliac haemodynamics may reveal occult aorto-iliac disease but does not show whether combined proximal and distal reconstruction will be required to provide symptomatic relief. Haemodynamic assessment of both segments may help in this respect. A haemodynamic assessment of the femoropopliteal segment of 72 limbs in 38 patients is reported. The segmental pressure drop between a common femoral arterial cannula and a below-knee occlusion cuff is compared with a non-invasive Doppler method combining both transit time and damping factor. Comparison is made using receiver operating characteristic (ROC) curve analysis. The measurement of segmental pressure drop is more accurate than the Doppler method in detection of femoropopliteal stenoses of greater than 50 per cent of the luminal diameter (P less than 0.05).     

Effect of meal on the physiological and physicochemical actions of potassium citrate

The effect of meals on the physiological and physicochemical actions of potassium citrate was examined in 8 patients with nephrolithiasis maintained on a constant metabolic dietary regimen. Potassium citrate (20 mEq. 3 times per day), whether given with food or on an empty stomach, significantly increased urinary pH, citrate and potassium, and decreased urinary calcium and ammonium. Moreover, potassium citrate decreased urinary saturation of calcium oxalate and uric acid, although it slightly increased that of brushite. However, there was no significant difference in these measures when the drug was given with meals from the time when it was given on an empty stomach. Thus, the effect of potassium citrate on urinary risk factors is unaffected by food.     

Tourette syndrome and neuropsychological performance

This study examined performance on a battery of neuropsychological tests in a sample of 28 patients with Tourette's syndrome (TS). Test scores were converted to age-corrected T-scores to control for the effect of age on test performance. The frequency of abnormal test performances was variable, but more frequent on motor and sensory tasks. Symptom severity as measured by the Tourette Syndrome Global Scale was inversely related to neuropsychological performance. In general, neuropsychological performance was mildly below average. The pattern of performance was similar to previous studies of TS patients.     

Evidence for a decrease in sympathetic control of intestinal function in the aged rat.

The ability of carbachol and isoprenaline to contract and relax respectively the longitudinal layer of ileal smooth muscle has been compared in rats aged six and twenty-four months. The concentration response curve to carbachol did not vary with the age of the animal. In contrast, the ability of isoprenaline to relax longitudinal smooth muscle precontracted with carbachol was significantly (p less than 0.02) reduced in the twenty-four month age group. This reduced response was due to a decrease in the maximal relaxation induced by isoprenaline rather than by a shift to the right of its dose-response curve. These results are discussed in the context of previous histochemical and microscopical studies which have shown a marked reduction in the density of the sympathetic innervation of the rat small intestine in old age.     

Role of substance P in several models of bladder inflammation

Substance P (SP) is a peptide found in the sensory nervous system which has multiple biologic effects including stimulation of muscle contraction, pain nociception, immune cell functions, plasma extravasation and a constellation of inflammatory effects. Here we investigate the role of SP in several animals models of bladder inflammation. Using the female Lewis rat, inflammation was induced using either xylene, lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (polyIC). Inflammation occurred rapidly (4 h) and was maintained in each model for at least 7 days. Each of these protocols decreased the bladder content of immunoreactive SP by approximately 50%, suggesting enhanced release. There was no change in the urinary frequency of these animals over 3 weeks, suggesting that urinary frequency changes are not mediated by acute inflammation. We also found that the SP receptor (NK₁) antagonist, (?)CP96345, was unable to block the inflammation produced by polyIC, suggesting that SP is not an obligatory mediator of immune cell stimulation in this model.     

Head injuries incurred by children and young adults during informal recreation.

To examine injuries related to playground equipment, children's vehicles, roller skates, and skateboards, 1991 data on emergency room patients younger than 25 years in the Consumer Product Safety Commission's 91 surveillance hospitals were used. Head injury was the primary diagnosis for an estimated 58,480 patients, exceeding the total number of head injuries to bicyclists younger than 25 years. The head injury rate decreased with age. The large number and high rate of head injuries in children involved in a variety of recreational activities suggests the value of multipurpose helmets.     

A comparison of acceleromyography and mechanomyography for determination of the dose–response curve of rocuronium in children

In order to compare an acceleromyograph (TOF-Guard^TM) 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 μg.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 μg.kg⁻¹, respectively, while these values determined by mechanomyography were 151 and 331 μg.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.