Clonidine prolongs canine tetracaine spinal anaesthesia

Using a randomized blind cross-over design, the comparative efficacy of clonidine in prolonging tetracaine spinal anaesthesia was studied in six mongrel dogs. Lumbar subarachnoid injections (1 ml) of: tetracaine 4 mg with clonidine 150 micrograms, tetracaine 4 mg with epinephrine 200 micrograms, tetracaine 4 mg, clonidine 150 micrograms, epinephrine 200 micrograms, and five per cent dextrose in H2O (vehicle) were administered randomly to each animal at 5-7 day intervals. Subarachnoid tetracaine produced a motor blockade of 186 +/- 58 (mean +/- SEM) min. Both clonidine and epinephrine produced a similar prolongation of tetracaine motor blockade, 135 per cent (p less than 0.01) and 116 per cent (p less than 0.05) respectively, compared with tetracaine alone. No motor blockade was observed in dogs receiving clonidine, epinephrine or five per cent dextrose in H2O. The addition of clonidine to tetracaine spinal anaesthesia produced a significant increase in duration of sensory blockade, 56 per cent (p less than 0.01) and 107 per cent (p less than 0.01) respectively, when compared to tetracaine with and without epinephrine. Subarachnoid clonidine alone produced a sensory blockade of 76 +/- 17 minutes, while only one animal receiving subarachnoid epinephrine had a sensory blockade (40 minutes). No neurologic deficits were observed in any of the animals. The study concludes that during spinal anaesthesia with tetracaine in dogs, clonidine is as effective as epinephrine in prolonging motor blockade, but is more effective in prolonging sensory blockade.     

Is antibiotic prophylaxis necessary for routine urodynamic investigations? A controlled study in 100 patients

The value of a prophylactic antibiotic before a routine cystometrogram has been assessed in a controlled trial of 100 patients. The infection rate was low and not statistically different in both groups. Subsequent symptoms of dysuria and haematuria had a mechanical aetiology.     

Brain uptake of α-[14C]methyl-para-tyrosine in the rat

The blood-brain permeabilities of L-[³H]tyrosine and the tyrosine hydroxylase (TH) inhibitor β-[¹⁴C]methyl-para-tyrosine ([¹⁴C]AMPT) were determined in rat striatum, a brain region rich in TH activity, and in other brain regions containing relatively little TH activity. In striatum, the unidirectional clearance rate (K₁) for L-[³H]tyrosine (6.2 ml hg- ^?1 min^?1) was significantly greater than the rates for L-[¹⁴C]AMPT (2.8 ml hg^?1 min^?1) and D-[¹⁴C]AMPT (0.8 ml hg^?1 min^?1). The apparent volume of distribution (V_f) for L-[¹⁴C]AMPT in striatum (72.5 ± 4.0 ml hg-¹) did not differ from the V_f in other brain regions. The homogeneous distribution of L-[¹⁴C]AMPT in rat brain indicates that labeled AMPT is unsuitable for the study of TH in vivo by quantitative autoradiography. © 1994 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.     

Crown of microfilaments in the extending cytoplasmic processes of medulloblastoma glial progenitors.

Microfilaments and microtubules play a part in the extension of neuronal processes but their roles in the formation of glial processes have not yet been determined. The objectives of this study were to determine the organization of microfilaments in differentiating glial progenitors (RB2 cells) and to study the effects of microfilament or microtubule disruption on process extension. Intense F-actin staining (crown of microfilaments) was observed at the leading edge of a small extending conical tip in differentiating RB2 cells, but was absent in process-bearing TE671 rhabdomyosarcoma cells. No significant difference was noted in the mean number of TE671 cells with processes treated with a microfilament disrupter from that of similarly treated controls. In contrast, a significant difference was noted in the mean number of RB2 cells with processes after microfilament disruption treatment from that of similarly treated controls. Microtubule disruption arrested extension and caused process retraction in both cell types. The results of this study demonstrate that microtubules play an equally important part in the extension and stabilization of the RB2 and TE671 processes. Moreover, the crown of microfilaments concentrated in the glial RB2 process (and not in the TE671 process) may be critical to its extension during differentiation.     

A multi-centre phase two study of intravesical epirubicin in the treatment of superficial bladder tumour

Epirubicin (4'-epi-adriamycin) was used in the treatment of widespread superficial carcinoma of the bladder. Thirty-seven patients received 50 mg in 50 ml of saline retained for 60 min. There was an overall response rate of 59% but this was of short duration. Thirty percent of patients progressed despite therapy. Therapy was associated with an incidence of side effects which necessitated therapy withdrawal in 12 (32.4%) patients. It is concluded that epirubicin, in the dose used in this study, cannot be recommended for routine intravesical chemotherapy and that further studies, at a reduced dosage, are necessary to evaluate this agent.     

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.