Omer Karim

The Guinea Pig as a Model of Gradual Urethral Obstruction

We developed a new model of partial urethral obstruction using the guinea pig. We placed jewelers jump rings loosely around the proximal urethra of immature guinea pigs and allowed the obstruction to develop gradually as the animal grew. After four or eight weeks of obstruction, we studied the filling and emptying characteristics of the bladder during continuous repetitive cycling under urethane anesthesia. Following this examination, bladders were removed and weighed. Wet weight was compared to urodynamic findings. We identified four abnormal urodynamic patterns: high pressure voiding, instability, poor compliance and decompensation. All obstructed bladders showed weight gain associated with muscle hypertrophy, but the degree of weight gain was different for each of the various urodynamic categories. High pressure voiding was associated with the least weight gain, whereas instability and decompensation showed the most weight gain. The results are consistent with a thesis that partial urethral outlet obstruction in the guinea pig gives rise to several distinct forms of abnormal voiding characterized by high pressure in the early stages, and progressing to more advanced forms of dysfunction characterized by instability and decompensation in the later stages.

The effect of experimental urethral obstruction and its reversal on changes in passive electrical properties of detrusor muscle.

The passive electrical properties of guinea pig detrusor muscle were studied in order to determine how bladder outflow obstruction and reversal might modify the electrical activity of the bladder and, thus, contractility. Experimental bladder outflow obstruction was produced in guinea pigs and resulted in an increase in bladder weight with a decrease in spontaneous electrical activity, membrane time constant and space constant. In addition, the membrane Na-K pump activity increased with obstruction. Following reversal of obstruction, bladder weight gain associated with obstruction was only partially reversible. The decrease in the membrane time constant induced by obstruction was almost fully reversible following release of obstruction. In contrast, the membrane space constant which reflects spread of current, in addition to spontaneous electrical activity, were only partially reversible. The membrane Na-K pump activity of the detrusor muscle decreased to control levels following reversal of bladder outflow obstruction. There was no significant change in the resting membrane potential of detrusor smooth muscle with either obstruction or following reversal of obstruction. These results suggest, that, the changes in the bladder smooth muscle membrane electrical properties induced by experimental bladder outflow obstruction are only partially reversible following release of obstruction. Furthermore, the results suggest that, the dysfunctional cystometric patterns associated with bladder outflow obstruction might not only be due to changes in detrusor innervation but, fundamental reorganization of the detrusors electrical syncytium with irreversible suppression of cell-to-cell transfer of electrical activity.

Developmental Alterations in the Fetal Lamb Bladder Subjected to Partial Urethral Obstruction in Utero

To identify the structural changes seen in the developing bladder subjected to outflow obstruction, a fetal lamb model was developed. With this model, which attempts to reproduce conditions such as those found in posterior urethral valves, quantitative biochemical parameters were used to evaluate the effects of partial outflow obstruction on detrusor cellularity and innervation in the developing bladder. Partial urethral obstruction was created in 9 fetal sheep (90 to 100 days gestation), 6 sham operated animals serving as controls. Fetuses were delivered at term and sacrificed. Bladders were removed and weighed. Mucosa free detrusor was assayed for DNA and choline acetyltransferase (ChAT) activity, indices of cell number and cholinergic innervation, respectively. In similar specimens of detrusor, cell ploidy and nuclear size were determined by flow cytometry and nuclear morphometry, respectively. The results showed that partial urethral obstruction in utero resulted in a significant increase in bladder weight (p < 0.05) and total detrusor DNA content (p < 0.01). With the increase in detrusor DNA content, there was a parallel increase in total detrusor ChAT activity. These results suggest that early development of the bladder is altered both on a cellular level (increase in cellularity) and a neural level (increase in cholinergic nerve density) under conditions of mechanical distension.

Analysis of the detrusor smooth muscle action potential

SummaryA method is described to record bladder smooth muscle action potential (AP) data and subsequently in digitized form analyze the constitutive elements of the AP. Manipulation of digitized data can give accurate descriptive information on the AP configuration and kinetics. In the future this type of analysis will hopefully lead to more precise, quantitative information on changes in the smooth muscle AP kinetics with disease states and facilitate a clearer understanding of the pathophysiological processes underlying changes in detrusor contractility.

SIR PERCIVAL POTT AND HIS MEMORABLE CONTRIBUTION TO THE EPIDEMIOLOGY OF THE CHIMNEY SWEEPER'S CANCER AND THE EPIDEMIC OF TUBERCULOSIS

was found to cause grain to sprout 70% of the time, but the sex could not be determined. Later, Hippocrates suggested that to determine a pregnancy, a woman could drink a honey and water mixture before sleep. If abdominal distension and cramps ensued, this would indicate a pregnancy. During the middle ages, uroscopy claimed to diagnose many disorders. In a 1552 text, pregnancy urine was described as a “clear, pale, lemon color leaning toward off-white”. It was not until the twentieth century that the science behind the urine pregnancy test was

Robotic assisted laparoscopic partial nephrectomy using contrast‐enhanced ultrasound scan to map renal blood flow

The paper describes novel real‐time ‘in situ mapping’ and ‘sequential occlusion angiography’ to facilitate selective ischaemia robotic partial nephrectomy (RPN) using intraoperative contrast enhanced ultrasound scan (CEUS).