Hyponatremia-related liver steatofibrosis and impaired spermatogenesis: evidence from a mouse model of the syndrome of inappropriate antidiuresis

PURPOSE

Hyponatremia is the most frequent electrolytic disorder in clinical practice. In addition to neurological symptoms, hyponatremia, even when mild/moderate and chronic, has been related to other manifestations, such as bone demineralization and increased risk of fractures. To better elucidate tissue alterations associated with reduced serum sodium concentration [Na⁺], we developed an in vivo model of hyponatremia secondary to the Syndrome of Inappropriate Antidiuresis.

METHODS AND RESULTS

Hyponatremia was induced in Foxn1^nu/nu mice by subcutaneous infusion of the vasopressin analog 1-deamino [8-D-arginine] vasopressin (dDAVP) for 14 days via osmotic mini-pumps. Mice in the control group were infused with isotonic saline solution. Serum [Na⁺] progressively decreased, with a nadir of 123.4 ± 2.3 mEq/L (mean ± SD, dDAVP 0.3 ng/h) and 111.6 ± 4.7 mEq/L (mean ± SD, dDAVP 0.5 ng/h). Evident signs of liver steatofibrosis were observed at histology in hyponatremic mice. Accordingly, the expression of proteins involved in lipid metabolism (SREBP-1, PPARα and PPARγ) and in myofibroblast formation (αSMA and CTGF) significantly increased. Furthermore, heme oxygenase 1 expression was up-regulated in Kupffer and hepatic stellate cells in the liver of hyponatremic mice. Testis alterations were also observed. In particular, the thickness of the seminiferous epithelium appeared reduced. The expression levels of PCNA and PTMA, which are involved in DNA replication and germ cells maturation, were markedly reduced in the testis of hyponatremic mice.

CONCLUSION

Overall, these findings shed new light on the possible consequences of chronic hyponatremia and prompt a more thorough evaluation of hyponatremic patients.

The V2 receptor antagonist tolvaptan counteracts proliferation and invasivity in human cancer cells

PURPOSE

Hyponatremia, the most frequent electrolyte alteration in clinical practice, has been associated with a worse prognosis in cancer patients. On the other hand, a better outcome has been related to serum sodium normalization. In vitro studies have shown that low extracellular sodium promotes cancer cells proliferation and invasiveness. Tolvaptan, a selective vasopressin receptor type 2 (V₂) antagonist, has been effectively used in the last decade for the treatment of hyponatremia secondary to the Syndrome of Inappropriate Antidiuresis. A few in vitro data suggested a direct role of tolvaptan in counteracting cancer progression, so far. The aim of this study was to evaluate the effect and the mechanism of action of tolvaptan in cell lines from different tumours [i.e. colon cancer (HCT-8), hepatocarcinoma (HepG2), neuroblastoma (SK-N-AS)].

METHODS AND RESULTS

First, we showed that these cell lines express the V₂ receptor. Tolvaptan significantly reduced cell proliferation with an IC₅₀ in the micromolar range. Accordingly, reduced levels of cAMP, of the catalytic α subunit of PKA, and a reduced pAKT/AKT ratio were observed. Tolvaptan effectively inhibited cell cycle progression, whereas it induced apoptotis. Furthermore, it reduced cell invasiveness. In particular, anchorage-independent growth and the activity of collagenases type IV were blunted in the three cell lines. Accordingly, tolvaptan counteracted the RhoA/ROCK1-2 pathway, which has a pivotal role in regulating cell movement.

CONCLUSIONS

Overall, these findings indicate that tolvaptan effectively inhibits tumour progression in vitro. Further studies should clarify whether the V₂ receptor might be considered a possible target in anti-cancer strategies in the future.

Posterior reconstruction and outcomes of laparoscopic radical prostatectomy in a high-risk setting

Posterior reconstruction was found to be associated with lower degree of anastomotic leakage and enhanced urinary continence at one and three months after extrafascial laparoscopic radical prostatectomy.

Background and Objectives:

To detail the technique and evaluate the impact of a personal modified posterior reconstruction technique (PDR) on the outcomes of extrafascial laparoscopic radical prostatectomy (eLRP) in a consecutive series of 52 patients affected by high-risk prostate cancer (HRPCa).

Methods:

From October 2007 to March 2012, 52 patients underwent PDR during eLRP for HRPCa. Fifty-four patients who underwent eLRP for HRPCa with no PDR were considered as historical controls. Mean operative time (MOT), mean catheterization time (MCT), % continence and quality of life (QoL) at a scheduled follow-up, % anastomotic leakage, % adjuvant therapy were compared between the groups. Percentage of continence and QoL were prospectively assessed by self-administered validated questionnaires (ICI-Q-SF; SF-36) at 1, 3, 6, and12 months.

Results:

PDR was associated wither higher continence rates at 1 and 3 mo (P = .028, P = .006), a lower incidence of cystographic leakage (P = .002), and an increased adjuvant radiotherapy rate (P = .008). At 1- and 3-mo interval, in the PDR group, we found a higher number of patients reporting better general health, (P = .01, P = .03) reduced role limitations due to physical health, (P = .02, P = .001), and emotional problems (P = .001, P = .02).

Conclusions:

PDR is associated with a lower degree of anastomotic leakage, and it significantly enhances urinary continence at 1 and 3 mo. The increased adjuvant radiotherapy rate and quality of life after surgery observed with our technique suggest that in the high-risk setting an early functional recovery may substantially influence the oncologic outcome of eLRP.

Urethroplasty with a Buccal Mucosa for Treatment of Anterior Urethral Strictures

We report the early results of urethroplasty with a buccal mucosa free graft as a dorsal onlay for treatment of anterior urethral strictures.

Materials and Methods

Since February 1997 to December 2003, 22 patients with recurrent anterior urethral strictures have been treated with buccal mucosa urethroplasty. Mean age of patients was 48.7 years (range 20 – 71). The etiology of strictures was inflammatory (7), iatrogenic (6), traumatic (3), idiopathic (6). Urethroplasty was performed with a free graft of buccal mucosa using dorsal onlay. The buccal mucosa onlay was sutured to the urethra and corpora cavernosa.

Results

At 37 month mean follow-up (range 5 to 83) the success rate was 95.5%.

Conclusions

Buccal mucosa free graft represents a simple surgical option and although longer follow up is needed preliminary results are excellent.