Critical Roles of Calpastatin in Ischemia/Reperfusion Injury in Aged Livers

Ischemia/reperfusion (I/R) injury unavoidably occurs during hepatic resection and transplantation. Aged livers poorly tolerate I/R during surgical treatment. Although livers have a powerful endogenous inhibitor of calpains, calpastatin (CAST), I/R activates calpains, leading to impaired autophagy, mitochondrial dysfunction, and hepatocyte death. It is unknown how I/R in aged livers affects CAST. Human and mouse liver biopsies at different ages were collected during in vivo I/R. Hepatocytes were isolated from 3-month- (young) and 26-month-old (aged) mice, and challenged with short in vitro simulated I/R. Cell death, protein expression, autophagy, and mitochondrial permeability transition (MPT) between the two age groups were compared. Adenoviral vector was used to overexpress CAST. Significant cell death was observed only in reperfused aged hepatocytes. Before the commencement of ischemia, CAST expression in aged human and mouse livers and mouse hepatocytes was markedly greater than that in young counterparts. However, reperfusion substantially decreased CAST in aged human and mouse livers. In hepatocytes, reperfusion rapidly depleted aged cells of CAST, cleaved autophagy-related protein 5 (ATG5), and induced defective autophagy and MPT onset, all of which were blocked by CAST overexpression. Furthermore, mitochondrial morphology was shifted toward an elongated shape with CAST overexpression. In conclusion, CAST in aged livers is intrinsically short-lived and lost after short I/R. CAST depletion contributes to age-dependent liver injury after I/R.

Mitochondrial ATP transporter depletion protects mice against liver steatosis and insulin resistance

Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disorder in obese individuals. Adenine nucleotide translocase (ANT) exchanges ADP/ATP through the mitochondrial inner membrane, and Ant2 is the predominant isoform expressed in the liver. Here we demonstrate that targeted disruption of Ant2 in mouse liver enhances uncoupled respiration without damaging mitochondrial integrity and liver functions. Interestingly, liver specific Ant2 knockout mice are leaner and resistant to hepatic steatosis, obesity and insulin resistance under a lipogenic diet. Protection against fatty liver is partially recapitulated by the systemic administration of low-dose carboxyatractyloside, a specific inhibitor of ANT. Targeted manipulation of hepatic mitochondrial metabolism, particularly through inhibition of ANT, may represent an alternative approach in NAFLD and obesity treatment.

Adenine nucleotide translocase (ANT) 2 promotes ADP/ATP exchange across the mitochondrial inner membrane. Cho et al. show that liver specific Ant2 deletion increases uncoupled respiration and protects mice against fatty liver and obesity-induced insulin resistance.

Differential expression of Listeria monocytogenes virulence genes in mammalian host cells

We have used RT-PCR and GFP-mediated fluorescence to analyse the regulation of PrfA-dependent virulence genes of Listeria monocytogenes during proliferation in mammalian host cells. Our data show that most of the PrfA-regulated virulence genes are more efficiently expressed, as measured by transcript levels, when L. monocytogenes is grown in macrophages and macrophage-like cells rather than in epithelial cells, hepatocytes or endothelial cells. The promoters for hly and plcA are predominantly activated within the phagosomal compartment, while those for actA and inlC are predominantly activated in the host cell cytosol. Expression of actA and plcB precedes that of inlC after infection of epithelial cells and macrophages. Little transcription of inlA or inlB is observed in epithelial cells and there is only slightly more in macrophages. In both cell types the level of transcription of the inlAB operon is lower than is seen under extracellular growth conditions in rich media, which is compatible with the assumption that InlA and InlB are not required during intracellular growth of the bacteria. Activation of the PrfA-independent iap promoter is also low during intracellular growth, although the gene product (p60) is required for cell viability. The levels of the PrfA-dependent virulence gene transcripts do not correlate with the amount of prfA transcript present, which is low under all intracellular conditions analysed, suggesting that the prfA transcript is either highly unstable in bacteria that are growing intracellularly, or that the small amount of PrfA produced is highly activated by additional component(s).

A new PrfA-regulated gene of Listeria monocytogenes encoding a small, secreted protein which belongs to the family of internalins

A mutant of Listeria monocytogenes EGD was constructed that carries an extended deletion removing the entire PrfA-regulated gene cluster from plcA to plcB and a second deletion inactivating the inlA gene. Upon supplementation of this mutant with multiple gene copies of prfA, a protein of 30 kDa was detected in the supernatant of the mutant strain. The gene encoding this protein was obtained by direct and inverse polymerase chain reaction using oligonucleotide primers that were deduced from partial amino acid sequences of the purified 30 kDa protein. The amino acid sequence of the gene product revealed a protein of 297 amino acids that carried eight repeat units with high homology to those of the two known internalin proteins A and B. This secretory protein, termed internalin C, is much smaller than InlA or InlB and its complete sequence is related to the two known internalins. The gene InlC is transcribed into a monocistronic mRNA from a single promoter which shows a typical consensus sequence for PrfA-binding at the position -40. In contrast to the transcription of the InlAB operon, which is downregulated after shift of an L. monocytogenes EGD culture from brain-heart infusion into minimum essential medium (MEM), transcription of inlC is induced in MEM like most of the other known PrfA-regulated virulence genes. In addition, InlC is strongly transcribed in the cytoplasm of phagocytic J774 cells whereas inlA is poorly transcribed under these conditions, suggesting that internalin C may play a role in a late stage of L. monocytogenes infection rather than in the uptake of L. monocytogenes by non-professional phagocytic cells. An InlC deletion mutant shows reduced virulence when tested in an intravenous mouse model, but intracellular replication of the mutant in Caco-2 and J774 cells appears to be comparable with that of the wild-type strain.

2'-Hydroxycinnamaldehyde from stem bark of Cinnamomum cassia

2'-Hydroxycinnamaldehyde, which inhibits farnesyl-protein transferase (FPTase), has been isolated from the stem bark of Cinnamomum cassia Blume. The biologically active agent in the extract has been purified by silica column chromatography and HPLC. The structure of the isolated compound was elucidated on the basis of 500 MHz NMR experiments.

A survey of trace elements in fresh-water fish and rice along the Han River by neutron activation analysis

For a case study of environmental pollution, radiochemical neutron activation analysis (RNAA) was applied to the crucian and rice collected along the Han River. The crucian was analyzed for three times in 1973, 1987, and 1990. Sixteen trace elements (Hg, Cd, As, Br, Cu, Na, K, Se, Cr, Hf, Rb, Fe, Zn, Co, La, and Cs) were determined by RNAA using distillation and diethyldithiocarbamate extraction methods. Contents of Na, K, Se, Hf, Fe, Zn, and Co were almost constant regardless of the sampling place and year. The contents of the other elements showed increasing trends down river, especially in the first investigation. At the lower part of the river, the contents showed decreasing trends with the time of sampling, especially during the first two investigations. These trends were typical for Hg and Cd. Rice was analyzed by the same method for 12 elements, and the results showed no regional trends, but have decreased after 1973.

Scimitar syndrome: anomalous venous drainage of the right lung into the inferior vena cava with malformation of pulmonary structure. A report of two cases

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Arrhythmia conference

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