Invited commentary

World Journal of Surgery -     

Resection of the perforated segment : A significant advance in treatment of diverticulitis with free perforation or abscess

As a result of improved medical management of chronic diverticular disease, perforation has become the most common indication for surgical intervention. During the past five years sixty-three patients underwent operation for colonic diverticular disease, of which forty-six were for perforation (generalized peritonitis in 8, abscess in 30, and fistula in 8). The eight patients with generalized peritonitis underwent emergency exploration for spreading peritoneal signs and were managed by resection of the perforated segment, end colostomy, and mucous fistula or Hartmann's pouch. Treatment of thirty-eight patients with abscess or fistula has also stressed primary resection of the perforated segment of colon. Resection and end colostomy without anastomosis was performed in three. Primary anastomosis with proximal diverting colostomy was performed in four. Primary anastomosis alone was done in thirty-one patients. There were no deaths. These results support primary resection of the involved colon with immediate or delayed anastomosis in the operative management of perforated diverticular disease.     

Thrombin-induced secretion of serotonin from platelets can occur in seconds

The platelet release reaction was studied by a new quenched-flow approach. Platelets labeled with 14C-serotonin were reacted for short times (up to 5 sec) with thrombin and then quenched with glutaraldehyde or paraformaldehyde. Serotonin secretion began within 1 sec and was nearly complete by 4 sec. Aggregation recorded by a resistive-particle counter was similarly fast. Therefore, the quenched-flow system reveals that serotonin secretion can occur more rapidly than estimated in earlier studies.     

Hepatitis B virus subgenotypes and basal core promoter mutations in Indonesia

AIM： To identify the distribution of hepatitis B virus （HBV） subgenotype and basal core promoter （BCP） mutations among patients with HBV-associated liver disease in Indonesia.
METHODS： Patients with chronic hepatitis （CH, n =61）, liver cirrhosis （LC, n = 62）, and hepatocellular carcinoma （HCC, n = 48） were included in this study. HBV subgenotype was identified based on S or preS gene sequence, and mutations in the HBx gene including the overlapping BCP region were examined by direct sequencing.
RESULTS： HBV genotype B （subgenotypes B2, B3, B4, 85 and B7） the major genotype in the samples, accounted for 75.4%, 71.0% and 75.0% of CH, LC and HCC patients, respectively, while the genotype C （subgenotypes C1, C2 and C3） was detected in 24.6%, 29.0%, and 25.0% of CH, LC, and HCC patients, respectively. Subgenotypes B3 （84.9%） and C1 （82.2%） were the main subgenotype in HBV genotype B and C, respectively. Serotype adw2 （84.9%） and adrq＋ （89.4%） were the most prevalent in HBV genotype B and C, respectively. Double mutation （A1762T/G1764A） in the BCP was significantly higher in LC （59.7%） and HCC （54.2%） than in CH （19.7%）, suggesting that this mutation was associated with severity of liver disease. The T1753V was also higher in LC （46.8%）, but lower in HCC （22.9%） and CH （18.0%）, suggesting that this mutation may be an indicator of cirrhosis.
CONCLUSION： HBV genotype B/B3 and C/C1 are the major genotypes in Indonesia. Mutations in BCP, such as A1762T/G1764A and T1753V, might have an association with manifestations of liver disease.     

Identification of sites responsible for the potentiating effect of niflumic acid on ClC-Ka kidney chloride channels

Background and purpose:

ClC-K kidney Cl⁻ channels are important for renal and inner ear transepithelial Cl⁻ transport, and are potentially interesting pharmacological targets. They are modulated by niflumic acid (NFA), a non-steroidal anti-inflammatory drug, in a biphasic way: NFA activates ClC-Ka at low concentrations, but blocks the channel above ∼1 mM. We attempted to identify the amino acids involved in the activation of ClC-Ka by NFA.

Experimental approach:

We used site-directed mutagenesis and two-electrode voltage clamp analysis of wild-type and mutant channels expressed in Xenopus oocytes. Guided by the crystal structure of a bacterial CLC homolog, we screened 97 ClC-Ka mutations for alterations of NFA effects.

Key results:

Mutations of five residues significantly reduced the potentiating effect of NFA. Two of these (G167A and F213A) drastically altered general gating properties and are unlikely to be involved in NFA binding. The three remaining mutants (L155A, G345S and A349E) severely impaired or abolished NFA potentiation.

Conclusions and implications:

The three key residues identified (L155, G345, A349) are localized in two different protein regions that, based on the crystal structure of bacterial CLC homologs, are expected to be exposed to the extracellular side of the channel, relatively close to each other, and are thus good candidates for being part of the potentiating NFA binding site. Alternatively, the protein region identified mediates conformational changes following NFA binding. Our results are an important step towards the development of ClC-Ka activators for treating Bartter syndrome types III and IV with residual channel activity.     

Manipulation of liver regeneration with macrophages to influence the hepatic progenitor cell niche

Insufficient regeneration of the adult liver is believed to cause failure to recover from severe liver disease. An undifferentiated cell population with stem-cell-like qualities known as hepatic progenitor cells (HPCs) is hypothesised to have a central role in regeneration of the adult liver during massive or chronic liver disease. Stem cells in other organ systems are believed to reside in a specialised microenvironment or niche that supports their maintenance and function. The existence of a hepatic stem cell niche might provide a means of therapeutically manipulating endogenous HPCs in vivo as a regenerative therapy.To investigate the physiological potential of HPCs to regenerate the mammalian liver, we have established a novel model of hepatocellular injury and HPC activation using genetic manipulation of hepatocytes. After hepatocyte senescence and death in this model (AhCre Mdm2^flox), HPCs expand and bring about the complete regeneration of the liver parenchyma.We demonstrate that a stereotypical niche, consisting partly of macrophages, exists in both animal models and correlating human disease. Using cell tracking, we show active recruitment of extrahepatic macrophages into this niche during injury. In health, intravenous injection of macrophages results in macrophage engraftment to the liver niche, with subsequent HPC activation and changes to liver structure and function.Within the niche, macrophages use paracrine signalling to control both HPC proliferation and cell fate via TWEAK (tumour-necrosis-factor-like weak inducer of apoptosis) and the Wnt signalling pathway, respectively. After hepatocellular injury, macrophages ingest hepatocyte debris, and release Wnt which promotes HPC differentiation into hepatocytes. TWEAK is vital for HPC proliferation in the AhCre Mdm2^flox model of regeneration. Here, the absence of TWEAK signalling results in liver failure and mortality.This work has demonstrated for the first time the ability of a solid organ to fully regenerate in the adult mammal from progenitor cells, and additionally highlights mechanisms by which this process can be modulated by either small molecule or cell therapy.FundingUniversity of Edinburgh.