J. Downie

Sympathetic activity in the proximal urethra in patients with urinary obstruction.

The effect of 10 mg. phentolamine intravenously on the urethral pressure profile was studied in male and female patients with lower urinary tract obstruction. A significant decrease of pressure occurred along the whole length of the urethra in both sexes, including the peak pressure zone in the male patient. This zone has been traditionally attributed to the external sphincter. It was concluded that the sympathetically innervated smooth muscle exerts a certain activity along the whole length of the proximal urethra. The phentolamine test may prove to be a useful adjunct to urethral profile studies in patients with lower urinary tract obstruction.

The kinetics of the vapor-phase oxidation of o-xylene over a vanadium oxide catalyst

Abstract The rate of oxidation of o -xylene was studied in a differential bed reactor over the following ranges of conditions: 290 to 310 °C, (0.5 to 3.0) × 10 −4 g-mole o -xylene/l, (5 to 100) × 10 −4 g-mole oxygen/l. The catalyst used was a vanadium oxide/potassium sulfate-promoted/silica, which had been used in previous kinetic studies. The data provide further support for the steady-state adsorption model proposed previously to describe the oxidation of naphthalene, toluene, and benzene. Particular attention was paid to the low oxygen concentration region, but no evidence was found to support the second order model proposed by Ioffe and Lyubarskii.

Sympathetic Dyssynergia in the Region of the External Sphincter: A Possible Source of Lower Urinary Tract Obstruction

Voiding cystourethrography demonstrated urethral constriction at the level of the external urinary sphincter in 10 patients with neurological dysfunctions. Ten mg. phentolamine mesylate intravenously alleviated this constriction, permitting better flow and reducing residual urine in 5 patients with a traumatic spinal injury, 2 with transverse myelitis and 1 who had had a cerebrovascular accident. Oral therapy with phenoxybenzamine hydrochloride, used in 7 of the 8 patients, reduced the post-void residual urine and produced improvement in hydronephrosis when present. These observations are consistent with the presence of a significant sympathetic component to obstruction at the region of the external sphincter in certain neurological disorders.

Analysis of the reaction network for the vanadia-catalyzed oxidation of ortho-xylene

Abstract The oxidation of o -xylene over a vanadium oxide catalyst was studied using a recirculation reactor over the following ranges of conditions: 310 to 330 °C oxygen feed concentration (0.25 to 0.75) × 10 −2 g moles/liter, o -xylene feed concentration (0.5 to 3.0) × 10 −4 g moles/liter, conversion 8 to 75%. The combination of a recirculation reactor and a quantitative rate modeling approach was shown to provide an effective method for the characterization of reaction networks which should be useful for catalyst screening and optimization studies. The extended form of the steady-state adsorption model was shown to provide a satisfactory description of the vanadia-catalyzed oxidation of o -xylene at high conversions with significant secondary reactions.

The Treatment of the Uninhibited Bladder with Dicyclomine

Symptomatic treatment of the uninhibited bladder has presented a challenge because of the lack of an effective, well tolerated smooth muscle relaxant for the bladder that can be used during an extended interval. In a preliminary study oral dicyclomine produced resolution or significant improvement of symptoms in 24 of 27 patients and an increase in bladder capacity by an average of 137 plus or minus 26 ml. (91 plus or minus 22 per cent) after 8 weeks of therapy. Additional controlled trials definitely are warranted.

Singularities in Multiresponse Modelling

Care is required when analysing multiple response data if misleading results are to be avoided. Box et al. [4] have warned of errors in analysis resulting from linear relationships among the response data, and have provided a detection procedure. This is effective for most situations; however, we have encountered two cases that require additional consideration. This paper extends the work of Box et al. to include these cases. The key issue is the detection of singularities in the multiresponse dispersion matrix, and a procedure for this is presented. The situation is also discussed in which linear dependencies in the data may be ignored to advantage. Illustrations are from chemical kinetics investigations.

Urethral Pressure Profile during the Spinal Shock Stage in Man: A Preliminary Report

The functional state of the proximal urethra in the spinal shock stage in man is not fully understood. We studied patients with spinal cord injuries during spinal shock and found that the urethral pressure profile had a normal configuration, the peak profile pressure increased with bladder filling and phentolamine (10 mg. intravenously) reduced the peak pressure, with empty and full bladders.

A Catheter Withdrawing Apparatus for Clinical Urethral Pressure Profile Studies

An apparatus for withdrawing a urethral catheter at a constant speed is described. The motor and the puller assembly are separate components so that the puller assembly can be autoclaved. By matching pulling speed to recorder chart speed a reproducible representation of urethral length can be obtained without using a displacement transducer. The apparatus has been used clinically for measuring urethral pressure profiles.

Action of coenzyme A on adenine derivative receptors in isolated tissues

The action of Coenzyme A (CoA) was investigated on the mechanical activity of four isolated tissues known to possess adenine derivative (AD) receptors that are sensitive, or resistant to blockade by theophylline. CoA produced a dose-related inhibition of the electrically stimulated myenteric plexus longitudinal muscle of the guinea pig ileum, and of the spontaneously contracting rabbit ileum. This effect was competitively antagonized by theophylline in both tissues. CoA caused a dose-related relaxation of the rat ileum. Low doses of CoA were not antagonized by theophylline but higher doses were antagonized by this drug. The rabbit detrusor, which was contracted by ATP and ADP, was not affected by CoA. Differences in the action of CoA at AD receptors in these four tissues, and in its antagonism by theophylline reflect a heterogeneity of these receptors. It is suggested that the simple sub-division of adenine derivative receptors into two types may be inappropriate.

A dual response analysis of the initial-rate data for the oxidation of propylene

Abstract Tan, H.S., Downie, J. and Bacon, D.W., 1990. A dual response analysis of the initial-rate data for the oxidation of propylene. Chemometrics and Intelligent Laboratory Systems , 9: 75–82. Initial-rate data for propylene oxidation over a bismuth molybdate catalyst were analysed using both single response and multiresponse model fitting to evaluate the benefits of using the latter procedure when independent measurements of propylene and oxygen conversions are available. The results of the multiresponse analysis show a marked improvement in the parameter precision.