D.J. Kok

Identification of Bladder Wall Layers by Raman Spectroscopy

PURPOSE We explored the applicability of Raman spectroscopy to in situ investigation of bladder wall tissue. MATERIALS AND METHODS Bladder wall tissue was obtained from a guinea pig model and frozen sections were used for Raman spectroscopic investigations. From each section 500 to 700 spectra were obtained in a 2-dimensional grid spanning the urothelium, lamina propria and muscle layer. The data set of spectra was subdivided into groups of similar spectra by a cluster analysis algorithm. With each group assigned a different color Raman maps of frozen sections were constructed based on group membership of measured spectra. These maps were then compared with histological and histochemical data obtained from hematoxylin and eosin and immunohistochemical staining for collagen I and III and for smooth muscle actin to correlate Raman spectral features with bladder wall structure and molecular composition. RESULTS Urothelium, lamina propria and muscle layers could be clearly distinguished based on Raman spectra. Lamina propria spectra were dominated by signal contributions of collagen and the smooth muscle layer showed strong signal contributions of actin. The urothelium had a relatively strong lipid signal contribution. CONCLUSIONS These results and the fact that Raman spectroscopy is rapidly evolving into a technology that can be applied in vivo by thin, flexible fiberoptic catheters indicate that prospects are good for in vivo analysis of the molecular composition of the normal and pathological bladder without biopsies.

Abnormal urine flow in boys with distal hypospadias before and after correction

PURPOSE We established the urine flow rate and the effect of surgical correction on that rate in patients with hypospadias. MATERIALS AND METHODS The urine flow rate, voided volume and residual urine were measured using an ultrasound flow probe and bladder scan in boys with distal hypospadias before operative correction in 42 with a mean age of 16 months, 3 and 9 months after operative correction in 28 and 11, respectively, and in a control group of 51 boys 0 to 3 years old (mean age 11 months). Long-term flow data were obtained retrospectively from the records of 63 patients with hypospadias 1 to 10 years after operation. RESULTS Of the controls 37% had mainly intermittent and sometimes fractionated flows, 4% had a plateau phase flow and 59% had mainly bell-shaped flow curves. The average maximum flow rate +/- SD was 6.8 +/- 4.1 ml per second and maximum flow rate/voided volume was 0.26 +/- 0.11 l per second. Of the boys with distal hypospadias 76% produced intermittent flows (fractionated in the majority) before correction. After correction this percent decreased to 50%. The average maximum flow rate was 7.5 +/- 2.5 ml per second before correction, and 6.6 +/- 2.8 and 7.2 +/- 1.8 ml per second 3 and 9 months after operation, respectively. Average maximum flow rate/voided volume was 0.22 +/- 0.12 l per second before, and 0.16 +/- 0.09 and 0.16 +/- 0.09 l per second 3 and 9 months after operation, respectively. In the long-term group maximum flow rate/voided volume was 0.13 +/- 0.11 l per second. The number of patients voiding with a plateau phase increased from 6% before to 13% and 17% after correction, respectively. An obstructive pattern was also observed in 41% of the long-term followup group. CONCLUSIONS An intermittent flow pattern is common in 0 to 3-year-old boys. It appears to be more common and more pronounced or fractionated in boys with distal hypospadias at the same ages. In relation to voided volume patients with hypospadias already produce an abnormally low urine flow rate before correction and even more so thereafter in the short and intermediate term. The corrective procedure increases the occurrence of flows with an obstructive pattern.

CHANGES IN BLADDER CONTRACTILITY AND COMPLIANCE DUE TO URETHRAL OBSTRUCTION: A LONGITUDINAL FOLLOWUP OF GUINEA PIGS

PURPOSE We established the longitudinal changes in bladder contractility and compliance as a result of urethral obstruction using a guinea pig model. MATERIALS AND METHODS Obstruction was induced in guinea pigs by a silver ring around the urethra. Urodynamic studies were performed longitudinally in individual animals. Bladder contractility and compliance were calculated from the measured bladder pressure and urine flow rate. RESULTS Bladder contractility developed in distinct phases. It reached a maximum 200% increase after an average of 3.25 weeks concomitant with an almost 2-fold increase in urethral resistance, remained 150% to 200% increased during weeks 4 to 7 and then decreased to starting levels again, while urethral resistance remained almost 2-fold increased. Bladder compliance decreased by 80% during the first 3 weeks and continued to decrease to 5% of its original value after 10 to 11 weeks. CONCLUSIONS Our data indicate that as a result of obstruction bladder function passes through a specific sequence of stages, including first a compensatory increase in contractility, then a stabilization phase and finally a decompensation state. In contrast bladder compliance shows a continuous decrease. The data suggest that for assessing how far a bladder has deteriorated due to obstruction a combination of functional and structural data may be warranted.

Raman spectroscopic detection of changes in molecular composition of bladder muscle tissue caused by outlet obstruction

Bladder outlet obstruction leads to loss of bladder function as a result of structural damage. Functional parameters of an obstructed bladder do not enable a prediction of the clinical outcome of removal of the obstruction. Therefore, other diagnostic methods are needed. This study presents first results of an approach based on Raman spectroscopy, which aims to detect changes in molecular composition of the bladder wall that may have diagnostic value. Raman spectroscopic mapping of unfixed sections of damaged and undamaged bladder wall from a guinea pig model of bladder obstruction was used to detect changes in composition of bladder muscle tissue. Collagen infiltration in muscle fibers was clearly visualized. Other compositional changes that are revealed include the accumulation of glycogen in obstructed bladder wall as well as an apparent but as yet unknown change in protein composition. In vivo Raman spectroscopic application may enable determination of bladder structure without the need for biopsies. These initial findings show that Raman spectroscopy can be a valuable diagnostic tool for evaluation of the extent of bladder structure loss.

Potential for recovery in bladder function after removing a urethral obstruction

We examined the relation between the loss of bladder function during obstruction and the potential for recovery of function after de‐obstruction.

Detrusor glycogen reflects the functional history of bladders with partial outlet obstruction

To assess the relationship between glycogen content in bladder detrusor tissue and historical bladder function in a guinea‐pig model of partial bladder outlet obstruction (PBOO).