Responses of the green-lipped mussel Perna viridis (L.) to suspended solids.

Laboratory experiments were conducted to investigate the lethal and sublethal effects of suspended solids on the survival and physiological, behavourial and morphological changes of the green-lipped mussel Perna viridis collected from Tolo Harbour, Hong Kong. Results showed that P. viridis survived in all test conditions of suspended solids from 0 to 1,200 mg/l over a period of 96 h. Physiological responses of the green-lipped mussel under 14-d exposure of suspended solids from 0 to 600 mg/l, followed by 14-d recovery in natural seawater, revealed no significant changes (p > 0.05) in oxygen consumption and dry gonosomatic index for treatments in different concentrations of suspended solids and exposure time. Changes in clearance rate were only found to be significant (p < 0.001) with exposure time. Responses in behavourial and morphological changes of the green-lipped mussel were also studied under similar experimental treatments and exposure time. Byssus production was significantly (p < 0.001) related to exposure time. Gill damage, however, was significantly greater in treatments (p < 0.001). Present findings suggested that P. viridis could tolerate a high level of suspended solids in the laboratory. There were dose-dependent effects of suspended solids on morphology of gill filaments. Implications of survival and responses of the green-lipped mussel to suspended solids in the marine environment are discussed.

The effects of testicular denervation on spermatogenesis in the Sprague-Dawley rat.

In the rat, regression of spermatogenesis during the chronic stages of spinal cord injury (SCI) occurs in the presence of normal function of the pituitary-testis hormone axis, thus suggesting that nonendocrine mechanisms might be involved. The current study examined whether disruption of neural input to the testis contributes to the cascade that leads to the regression of spermatogenesis. Four weeks after denervation of the superior spermatic nerve (SSN), testis weight was 25% lower (p < 0.01) than that of the contralateral sham-operated testis. Defects in spermatogenesis including phagocytosis of mature spermatids, vacuolization of spermatid nuclei, delayed spermiation and incomplete cellular associations were observed in >60% of the tubules. In the remaining 30-40% of tubules, the seminiferous epithelium was severely regressed. While cutting the inferior spermatic nerve (ISN) alone did not affect spermatogenesis significantly, it enhanced the effect of SSN denervation on both spermatogenesis and testis weight (p < 0.01). Spermatogenesis was totally regressed in the SSN/ISN-denervated testes. At this time, quantitatively normal spermatogonial proliferation was maintained in SSN- or ISN-denervated testes. Twelve weeks after surgery, regression of the seminiferous epithelium characterized by absence of proliferating spermatogonia, while undifferentiating spermatogonia were present, was observed in all SSN-denervated testes. At this time, regression of the seminiferous epithelia also occurred in >30% of the tubules in ISN-denervated testes. At both times, serum follicle-stimulating hormone, luteinizing hormone and testosterone levels were normal and >60% of normal testicular testosterone concentrations were maintained in the denervated testes. These results indicate that disruption of neural input to the testis is not a cause for the decrease in spermatogonial proliferation during the acute phase of SCI, but may contribute to the chronic effects of SCI on spermatogenesis.

Ureteroneocystostomy: to drain or not to drain.

PURPOSE: Indications for the use of external abdominal drains after ureteral reimplantation are not well defined. We determine the nature of the drainage fluid as well as the current use of drains by pediatric urologists. MATERIALS AND METHODS: We prospectively evaluated 15 consecutive patients 7 months to 19 years old who underwent unilateral or bilateral intravesical ureteroneocystostomy for primary vesicoureteral reflux. All patients were treated with a urethral Foley catheter and closed suction Jackson-Pratt abdominal drain. Fluid from the Jackson-Pratt drain and Foley catheter was analyzed for urea and creatinine on postoperative day 1, and compared to serum values. The Foley catheter was removed after the urine became clear, and the Jackson-Pratt drain was removed after drainage was 5 ml. or less for 12 hours. In addition, a questionnaire was distributed to 268 pediatric urologists to determine current practice regarding the use of routine postoperative drains. RESULTS: Urea and creatinine from the Jackson-Pratt drains in all 15 patients were consistent with serum values. The Foley catheter and Jackson-Pratt drain were removed an average of 3 and 4 days postoperatively, respectively. There were 186 responses from the 268 questionnaires distributed (69.4%). Of the pediatric urologists surveyed 70.4% performed intravesical ureteral reimplantation exclusively, 5.9% extravesical reimplantation exclusively and 23.7% both techniques. Of the group surveyed 73.1% placed external abdominal Jackson-Pratt or Penrose drains, although 26.5% of those who routinely used external drains believed that they were probably unnecessary. Of the physicians who placed drains 53.7% believed that the drainage fluid had some component of urine. CONCLUSIONS: In our small prospective study group we demonstrated that external abdominal drainage fluid is consistent with serum despite the popular belief that it may have some component of urine. The gynecological literature has shown repeatedly that there is no increase in morbidity after radical hysterectomy and pelvic lymph node dissection when no external abdominal drains are used. Although to our knowledge there are no previous reports of drain use after ureteral reimplantation, 26.9% of pediatric urologists currently do not place external abdominal drains with no apparent increase in morbidity. Larger prospective cohorts with long-term followup are needed to address adequately the issue of whether drains are needed after uncomplicated ureteral reimplantation.

Partial purification and characterization of neutral proteases in lymph nodes of rats with experimental allergic encephalomyelitis.

Two kinds of neutral protease activities in lymph nodes from Lewis rats with acute experimental allergic encephalomyelits (EAE) have been separated and partially purified and characterized. A soluble enzyme preparation enriched by gel filtration and ion-exchange chromatography hydrolyzes myelin basic protein, polylysine, and other basic proteins with an optimum pH at 6.0-6.5. It is inhibited by p-chloromercuribenzoate, and thus appears to be a mixture of thiol proteases. Another fraction containing proteolytic enzyme activity is strongly bound to the insoluble lymph node residue, and it also hydrolyzes myelin basic protein and histone, but not polylysine. It has a pH optimum above 7.5, is inhibited by phenylmethylsulfonyl fluoride, thus resembling elastase, but does not hydrolyze elastin-Congo red. The insoluble enzyme preparation hydrolyzes basic protein to 4-5 peptides in a pattern on polyacrylamide gels resembling that of the hydrolysis of basis protein by whole lymphocytes; the soluble enzyme mixture produces small fragments not retained on gels. Lymphocytes are a major component of the cells infiltrating the nervous system in experimental allergic encephalomyelitis, and neutral proteases contained in these cells may contribute to the degradation of myelin, especially of the basic protein.