Gas chromatographic analysis of urinary dimercaptosuccinic acid.

The therapeutic use of disulfhydryl compounds such as 2,3-dimercaptosuccinic acid (DMSA) for the treatment of heavy metal poisoning has generated a requirement for specific and sensitive methods to determine those compounds in biological media. We have developed a gas chromatographic assay for DMSA in urine. The use of capillary column technology eliminates the requirement for a preliminary clean-up step. Samples are first reduced electrochemically to liberate DMSA present as disulfides. The reduced product is then extracted into ethyl acetate and the organic phase removed by evaporation. The residue is derivatized with N,O-bis (trimethylsilyl) acetamide for gas chromatography. The silylated DMSA derivative is then detected with a flame ionization detector. The detection limit for DMSA is 1.9 nmol per 1-microliter aliquot of derivatized extract injected on column (detector sensitivity at 1.10(-11) A/mV). The utility of the method was demonstrated by analyzing the urine of rats orally dosed with DMSA.

Urodynamic investigation predicts bladder dysfunction at an early stage after abdominoperineal resection of the rectum for cancer.

In a prospective study, 25 consecutive patients (14 men and 11 women) who underwent abdominoperineal resection of the rectum were urodynamically investigated before surgery and 10 days, one month, and three months after the operation. Nine men and three women (48% and 95% confidence limits; range 28% to 69%) developed voiding disturbances 10 days after the operation. One man and one woman developed incomplete lower motor neuron lesion (8% and 95% confidence limits; range 1% to 26%). At follow-up 3 months after surgery, five patients (20% and 95% confidence limits; range 7% to 41%) had still voiding disturbances: two patients with lower motor neuron lesion and three men with bladder outlet obstruction caused by prostatic hypertrophy. The three men underwent transurethral resection of the prostate 6 months after excision of the rectum. It is concluded that the risk of neurogenic bladder and voiding dysfunction is a minor problem. Cystometry performed before removal of the vesical catheter around the tenth postoperative day will diagnose patients with neurogenic bladder dysfunction. If voiding symptoms persist beyond 3 months after the operation, further urodynamic investigations should be undertaken to find patients with bladder dysfunction not due to lesion of the peripheral parasympathetic nerves to the bladder, which could demand surgery.