Lack of effects of prenatal exposure to lidocaine on development of behavior in rats

The objective of this investigation was to study the effects of lidocaine upon postnatal development of the rat. Lidocaine, 6 mg/kg (21 mumol/kg), was given to a group of 12 rats. Injections were administered intramuscularly, bilaterally in the masseter muscles, once a day on days 10 and 11 of pregnancy. Twelve control rats were given physiologic saline. Clinical signs, mortality, body weight, and food consumption were recorded during pregnancy and lactation. The duration of gestation was also recorded. The development of the offspring was monitored by tests of spontaneous activity, nociception, learning ability, and physical development. No clinical signs of adverse reactions were seen in any of the groups. In the majority of the learning ability tests, the control and lidocaine-treated groups showed similar results. However, in the schedule of differential reinforcement of low rates of responding (DRL 20), the lidocaine-exposed males received more reinforcements than the controls and made fewer responses. In the tests of nociception, a significant difference between sexes was recorded, in that the females were more sensitive than the males in the shock-titration test. Physical development, as monitored by swimming ability and spontaneous activity, showed no inter-group difference. The present results indicate that prenatal exposure to lidocaine fails to result in postnatal impairment of the development of behavioral performance of a wide range of tasks.     

Vestibular-nerve inputs to the vestibulo-ocular reflex: a functional-ablation study in the squirrel monkey

Advantage was taken of differences in the electrical excitability of vestibular-nerve fibers to characterize the afferent input to the canal-related vestibulo-ocular reflex. Large anodal (inhibitory) currents, when delivered to both ears, result in a selective, reversible ablation of irregular afferents. Their background discharge and responses to head rotations are temporarily abolished. The same currents have less effect on the background discharge and no effect on the rotational sensitivity of regular afferents. Eye movements were evoked by head rotations in alert monkeys. The ablating currents did not alter the ocular responses to sinusoidal head rotations in yaw or pitch planes. Responses to rapid changes in head velocity were similarly unaffected. It is concluded that irregular afferents do not make a net contribution to the reflex. Slow-phase eye movements evoked by unilateral galvanic currents are consistent with this conclusion. The results are incorporated into a systems model of the reflex. There are three conclusions from the model: (1) the signal to motoneurons consists of the sum of three components related, respectively, to head velocity, eye position, and filtered eye velocity; (2) regular afferents provide the best match to the dynamic requirements of the reflex; and (3) the central pathways responsible for all three signal components receive regular inputs.     

A comparison of motor unit behaviour in young and aged subjects

We evaluated motor unit behaviour in young and aged subjects during ramped tension development and release to 10% maximum voluntary contraction requiring 10 seconds to complete. Six young and six elderly adults performed isometric abductor digiti minimi muscle contractions while motor units were recorded with implanted fine wire electrodes. Computer interactive programs yielded interspike interval (ISI) data for 16 units from the young and for 15 units from the aged subjects. Mean ISIs for young were 88.4 ms for shortening and 96.5 ms for lengthening contractions. Units from the aged had ISIs of 110.5 ms and 117.1 ms for shortening and lengthening contractions. Some evidence for between-group differences in firing pattern during ascending and descending ramps was also found.     

Rotational ablation of coronary artery lesions using single,large burrs

Previous clinical use of the Rotablator^(TM) In coronary artery disease has involved a sequential increase in burr sizes up to 2 mm in diameter and has often utilized balloon adjunct to achieve an optimal result. We report our experience and describe our technique using a single, large burr (2.25, 2.5, or 2.75 mm diameter) without balloon assistance. The burr size was selected to approximate 70–90 percent of the apparent normal lumen diameter. Thirty-one patients with 36 lesions of complex morphology (eccentric, irregular, calcified, ulcerated, at bends, at bifurcations, completely occluded, as well as balloon failures) were successfully treated with the Rotablator^(TM). Results were assessed by computerized quantitative angiography. The percent diameter stenosis (mean ± SD) for the group was reduced from 69.8 ± 11.3% to 30.9 ± 10% (p < 0.001). The mean absolute diameter stenosis increased from 0.9 ± 0.3 mm to 2.2 ± 0.3 mm (p < 0.001). Angiographically visible dissections were seen in 4 patients and were uncomplicated in 2. One patient had a non-Q-wave myocardial infarction. A fourth patient had a presumed acute occlusion 36 hr after the procedure, necessitating emergency bypass surgery, but without Q waves on the electrocardiogram or wall-motion abnormalities on the echocar-diogram. Nitroglycerin was infused through the Rotablator^(TM) catheter and has considerably lowered the degree and frequency of spasm. No other acute complications occurred. The mean procedure time using a single burr was shorter than when multiple burrs were used: 56.5 vs. 97.3 min, respectively (p < 0.05). The use of a single, large-size Rotablator^(TM) burr is an effective method of treating complex coronary stenoses without balloon assistance and has an encouragingly low complication rate and short procedure time. © 1992 Wiley-Liss, Inc.     

Common bile duct calculi: updated experience with dissolution with methyl tertiary butyl ether

The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.     

Clinical MR imaging with a Helmholtz-type surface coil

Limited-field-of-view radio-frequency receiver antennas provide improved near-field sensitivity for magnetic resonance imaging by decreasing the antenna volume. The Helmholtz-type surface coil, consisting of two flat rings, is an organ-encompassing antenna that takes advantage of this principle to yield an improved signal-to-noise ratio (S/N). The coil was tested in a group of 50 patients and 16 healthy volunteers. Images obtained with the Helmholtz coil demonstrated quantitatively superior S/N of 2.2-fold or greater than that of comparison body coil images, as well as qualitatively superior anatomic resolution.     

Effect of endothelium mimicking self-assembled nanomatrices on cell adhesion and spreading of human endothelial cells and smooth muscle cells

The goal of this study is to develop unique native endothelium mimicking nanomatrices and evaluate their effects on adhesion and spreading of human umbilical vein endothelial cells (HUVECs) and aortic smooth muscle cells (AoSMCs). These nanomatrices were developed by self-assembly of peptide amphiphiles (PAs) through a solvent evaporation technique. Three PAs, one containing the Tyr-Ile-Gly-Ser-Arg (YIGSR) ligand, the second containing the Val-Ala-Pro-Gly (VAPG) ligand, and a third without cell adhesive ligands, were developed. Cell adhesion and spreading were evaluated by a PicoGreen-DNA assay and live/dead assay, respectively. Our results show that PA-YIGSR significantly enhances HUVEC adhesion (26,704 ± 2708), spreading (84 ± 8%), and proliferation (50 ± 2%) compared with that of other PAs. PA-VAPG and PA-YIGSR showed significantly greater AoSMC adhesion compared with that of PA-S. PA-VAPG also showed significantly greater spreading of AoSMCs (63 ± 11%) compared with that of other PAs. Also, all the PAs showed significantly reduced platelet adhesion compared with that of collagen I (control). These findings would facilitate the development of novel vascular grafts, heart valves, and cell-based therapies for cardiovascular diseases.From the Clinical EditorThe goal of this study was to develop unique native endothelium mimicking nanomatrices and evaluate their effects on adhesion and spreading of human umbilical vein endothelial cells (HUVECs) and aortic smooth muscle cells (AoSMCs). These nanomatrices were developed by self-assembly of peptide amphiphiles through a solvent evaporation technique. The findings are expected to facilitate the development of novel vascular grafts, heart valves, and cell based therapies for cardiovascular diseases.