D-glucose and NaCl enhance the expression of aquaporin-1: inhibition of both by cholera toxin

AIM: To determine whether glucose, NaCl and/or cholera toxin modify the expression of aquaporin-1 (AQP-1) water channel. METHODS: Aquaporin-1 gene expression was studied using primary cultures of human renal proximal tubule epithelial (HRPTE) cells. RESULTS: D-Glucose and NaCl (500 mosm/kg.H(2)O each) enhanced AQP-1 expression 2.4-fold (p < 0.05) and 4.0-fold (p < 0.01), respectively, which could be blocked 73 and 70% (p < 0.01), respectively, by cholera enterotoxin (10(-7) M). Angiotensin II (10(-6) M and 10(-8) M), vasopressin (10(-8) M) and/or atrial natriuretic peptide (10(-8) M) did not affect AQP-1 expression. Hyperosmolar Reno-60 and Hypaque-76 contrast agents at 500 mosm/kg.H(2)O and isomolar Visipaque at 25% (v/v) concentration(s) also increased AQP-1 expression 3.8- to 5.0-fold (p < 0.01) in HRPTE cells which also were inhibited by cholera toxin from 41% (p < 0.05) to 71% (p < 0.01). AQP-1 was translocated from the cytosol to the membrane of HRPTE cells and hyperosmolarity enhanced this translocation 2.5-fold (p < 0.01). CONCLUSIONS: The increased urinary concentrating ability in proximal segment of the diabetic kidney associated with increased plasma glucose may be mediated via glucose's ability to enhance AQP-1 expression, which leads to a more concentrated urine. The decrease in urinary flow secondary to cholera toxin exposure, on the other hand, may be mediated indirectly by cholera toxin's inhibition of aquaoporin-1 gene expression.     

Permeable tubes increase the length of the gap that regenerating axons can span

After placement of stumps of transected rat sciatic nerve in an impermeable tube, the maximum gap the axons can span is 10 mm. The present study shows that the regenerating axons cross much longer gaps if the tube is made permeable. This improvement does not require another nerve as a transplant nor the preplacement of extracellular materials in the tube. Possible mechanisms for this improvement are discussed.     

Effects of sciatic nerve regeneration on axonal populations in tributary nerves

The present study tests 2 hypotheses: (1) that the numbers of axons that regenerate into a tributary nerve are in part dependent on the type of lesion used to transect the axons in the parent nerve; and (2) that the numbers of axons that regenerate will be different in different tributary nerves. Axons were counted in the sural nerve and the nerve to the medial gastrocnemius muscle 8 weeks following crush, simple transection, transection with removal of 4 mm and transection with removal of 8 mm of the sciatic nerve in the rat. The counts of myelinated and unmyelinated axons are presented in the text. If axon numbers in the 2 nerves are normalized, the proportion of regenerated to normal myelinated axon numbers are approximately the same in the 2 nerves, with more regenerated axons than normal following crush, simple transection, or 4 mm gap transection and fewer following 8 mm gap transection. The unmyelinated axons behave differently. In the nerve to the medial gastrocnemius muscle, the numbers of unmyelinated axons are greater than or equal to the normal numbers following our various surgical paradigms whereas in the sural nerve there are always fewer unmyelinated axons than normal. These findings indicate that the above hypotheses are correct for the nerves tested in the rat.     

Numbers of regenerated axons in tributary nerves following neonatal sciatic nerve crush in rat

We determined numbers of regenerated axons in 5 tributary nerves 8 weeks after the complete axonal loss that follows crush of newborn rat sciatic nerve. The major findings are: (1) that proportionately many more axons are lost in cutaneous than in muscle nerves, (2) that myelinated axons are greatly increased over normal in two of the muscle nerves, and (3) that unmyelinated axons are normal or close to normal in muscle nerves. The major conclusions are: (1) there is a different pattern of regeneration in cutaneous as compared to muscle nerves after neonatal sciatic nerve crush, and (2) the responses after neonatal crushes are different than after adult nerve crushes.     

Integrin alpha2beta1 recognizes laminin-2 and induces C-erb B2 tyrosine phosphorylation in metastatic human melanoma cells

Previous studies have shown that tumor cells with metastatic propensity secrete more of the laminin alpha2 chain than non-metastatic tumor cells do, and that laminin-2, which contains the alpha2 chain, promotes cell adhesion better than laminin-1 (Jenq et al. (1994). Differentiation, 58, 29-36). The current studies were designed to determine whether a correlation exists between the expression of the laminin-2 isoform and the metastatic phenotype in melanoma cells. We found that expression of the laminin-2 isoform was upregulated in the metastatic melanoma cell lines tested. Cell attachment studies showed that metastatic melanoma cells attached more efficiently to laminin-2 substrates. Studies on integrin expression revealed that the presence of alpha2beta1 integrin correlated with expression of the laminin-2 isoform in metastatic melanoma cells; anti-integrin alpha2 antibody prevented cell attachment to laminin-2 substrates. The data suggest that the alpha2beta1 integrin is the receptor mediating cell attachment to the laminin-2 isoform. This interaction, mediated by the alpha2beta1 integrin, stimulates secretion of the 72 kD type IV collagenase and induces a specific 185 kD protein tyrosine phosphorylation. The 185 kD tyrosine-phosphorylated protein was identified as the p185/C-erb B2 oncoprotein by immunoprecipitation. These studies suggest that upregulation of expression of the laminin-2 chain correlates with the metastatic phenotype of melanoma cells and provides evidence that the specific p185/C-erb B2 tyrosine phosphorylation may be involved in integrin-mediated signaling during tumor cell invasion and metastasis.     

Rifle classification for predicting in-hospital mortality in critically ill sepsis patients

Severe sepsis and septic shock, often complicated by acute kidney injury (AKI), are the most common causes of mortality in noncoronary intensive care units (ICUs). This study investigates the outcomes of critically ill patients with sepsis and elucidates the association between prognosis and risk of renal failure, injury to the kidney, failure of kidney function, loss of kidney function, and end-stage renal failure (RIFLE) classification. A total of 121 sepsis patients were admitted to ICU from June 2003 to January 2004. Forty-seven demographic, clinical, and laboratory variables were prospectively recorded for post hoc analysis as predictors of survival on the first day of ICU admission. Overall in-hospital mortality rate was 47.9%. Mortality was significantly associated (chi-square for trend; P < 0.001) with RIFLE classification. Septic shock, RIFLE category, and number of organ system failures on the first day of ICU admission were independent predictors of hospital mortality according to forward conditional logistic regression. The severity of RIFLE classification correlated with organ system failure number and Acute Physiology and Chronic Health Evaluation (APACHE) II to IV and sequential organ failure assessment scores. Cumulative survival rates at 6-month follow-up after hospital discharge significantly (P < 0.05) differed between non-AKI versus RIFLE injury, non-AKI versus RIFLE failure (RIFLE-F), and RIFLE risk versus RIFLE F. At 6-month follow-up, full recovery of renal function was noted in 85% of surviving patients with AKI (RIFLE risk, RIFLE injury, and RIFLE-F). In conclusion, these findings are consistent with a role for RIFLE classification in accurately predicting in-hospital mortality and short-term prognosis in ICU sepsis patients.     

ORIGINAL ARTICLE: Leptin on Peritoneal Macrophages of Patients with Endometriosis

Citation Wu M‐H, Huang M‐F, Chang F‐M, Tsai S‐J. Leptin on peritoneal macrophages of patients with endometriosis. Am J Reprod Immunol 2010; 63: 214–221 Problem The expression of cyclooxygenase (COX)‐2 is considered as a marker of macrophage activation and has been implicated in the development of endometriosis. Leptin is an immunomodulator, which may also affect the development of endometriosis. However, how leptin contributes to these pathological processes has not been completely understood. The aim of this study was to investigate the effects of leptin on peritoneal macrophages and its relationship with endometriosis. Methods of study Peritoneal fluid from 60 women of reproductive age was obtained while they underwent laparoscopy. Forty patients had endometriosis and 20 patients did not have endometriosis. The concentration of leptin in the peritoneal fluid and prostaglandin F_2α levels was measured by ELISA, and the other protein expression using Western blot when peritoneal macrophages were stimulated with leptin. Results Concentration of leptin in peritoneal fluid was increased in patients with endometriosis compared with disease‐free normal control. Functional leptin receptor was present in peritoneal macrophages. Treatment of peritoneal macrophages with leptin induced COX‐2 expression. Production of prostaglandin F_2α by peritoneal macrophages was increased after leptin stimulation in women with endometriosis. Conclusion Elevated concentration of leptin in peritoneal fluid may contribute to the pathological process of endometriosis through activation of peritoneal macrophages.