The hygienic requirements for the construction, operation and water quality of swimming pools

Data concerning operative treatment of 227 patients with lithiasis of the extrahepatic biliary ducts, covering an eleven-year period (1985 to 1995 inclusive), are presented. In all cases diagnosis and operation are done in the Second Surgical Clinic at the Medical University--State University Hospital "Alexandrovska"--Sofia. By type the surgical interventions are distributed as follows: external drainage of hepaticocholedochus--122 cases (53.74 per cent), choledochoduodenostomy 69 (30.39 per cent) and transduodenal papillosphincterotomy 36 (15.85 per cent). Fifteen patients develop postoperative complications (6.60 per cent), and in five patients the outcome is fatal with postoperative lethality amounting to 2.20 per cent. The basic indications for the various types of surgical interventions are established.     

Irritating effects of disinfection by-products in swimming pools

Compounds which can occur as disinfection by-products (DBP's) in swimming pool water were examined for their mucous membrane irritating potential. Previous studies using the rabbit eye test (Draizé test) have shown that the irritating potential of typical concentrations of free and combined chlorine are insufficient to explain the degree of eye irritation that can result from exposure to swimming pool water. Other DBP's which may be responsible for eye irritation include halogenated carboxyl compounds (HCC's) which act as precursors during the formation of chloroform. In this study, a modified HET-CAM Test (Hens Egg Test at the Chorion Allantois Membrane) has been used to investigate the mucous membrane irritating effects of HCC's. Some of the compounds tested were found to have a significantly increased irritating effect when compared to a chlorine/chloramine mixture of the same concentration, several mixtures of HCC's where even more active at lower concentrations than single compounds. However, the irritating effects of individual compounds as well as of mixtures of HCC's were not sufficiently intense to allow the identification of those compounds specifically responsible for the overall observed increase in irritation. HCC's were therefore tested in the presence of aqueous chlorine solution. When combined with aqueous chlorine, a number of compounds exhibited significantly enhanced effects. Our results show that the eye irritating effects of low concentrations of DBP's can be investigated using a modified HET-CAM assay. Moreover, results obtained using this assay suggest that the mucous membrane irritating potential of swimming pool water is a consequence of the effects and synergistic action of a number of DBP's in the presence of chlorine. Further work should be carried out in order to establish an indicator for eye irritating effects of swimming pool water.     

Faecal pollution of ocean swimming pools and stormwater outlets in eastern Sydney

BACKGROUND: We evaluated routine transition zone biopsies for the detection of prostate cancer. METHODS: Systematic sextant transrectal biopsies, including 2 systematic transition zone biopsies (sextant biopsy group), were performed on 196 consecutive patients. Biopsies were based on indications from digital rectal examination and/or a serum PSA level greater than 4.0 ng/mL. During the same period, 21 patients with persistently elevated PSA levels and earlier negative systematic biopsies also had the sextant biopsy (re-biopsy group). The sextant biopsy group was compared with 124 cases in our previous cancer detection program who had systematic quadrant biopsies targeted to the peripheral zone (quadrant biopsy group). RESULTS: Between the sextant and quadrant biopsy groups, the difference in rate of cancer detection was not significant statistically. Of the sextant biopsy group, 64 (33%) demonstrated malignancy, including 9 (4.6%) with cancer found exclusively in the peripheral zone and 55 (28%) both in the peripheral and transition zones. No cancer was found exclusively in the transition zone. Of the re-biopsy group, all 4 cancers (19%) were detected in the transition zone, 2 of them exclusively in the transition zone. CONCLUSION: Routine transition zone biopsies did not increase the detection rate of prostate cancer. Systematic transition zone biopsies proved useful to the patients with persistently elevated PSA values and negative results in previous systematic peripheral zone biopsies.     

Blood and breath analyses as biological indicators of exposure to trihalomethanes in indoor swimming pools

The establishment of in vitro culture systems provides an accessible means to study events within the immune system. In contrast to either dispersed suspension or two-dimensional monolayer culture, the explantation of tissue fragments under organ culture conditions is, to date, the only method which allows essential three-dimensional cellular interactions to be maintained under conditions which permit controlled experimental manipulation in vitro. Recent modifications of explant technology, particularly within the area of fetal thymic organ culture, now allow the controlled reassociation of defined cellular subsets and manipulation of gene expression, under conditions where the functioning of both lymphoid and stromal cell types closely resembles that in vivo.     

The effect of increased response requirements on discriminative performance of the domestic hen in a visual acuity task

Six domestic hens were trained in a spatial discrimination task. A controlled reinforcement procedure insured that the ratio of scheduled and obtained reinforcement remained equal. Gray stimuli and gratings ranging in spatial frequency from 1 to 10 cycles per millimeter were presented in seven descending series of probes. The response requirement to the sample key was varied from fixed ratio 1 to fixed ratio 40 in seven experimental conditions. An increase in response requirements from fixed ratio 1 to fixed ratio 5 and fixed ratio 10 resulted in significantly higher accuracy at discriminable grating values. Further increases in response requirements did not consistently improve performance. Generally, response biases increased and occasionally became extreme for probes at finer gratings with increased response requirements.