Effects of the Amino Acid Constituents of Microcystin Variants on Cytotoxicity to Primary Cultured Rat Hepatocytes

Microcystins, which are cyclic heptapeptides produced by some cyanobacterial species from algal blooms, strongly inhibit serine/threonine protein phosphatase and are known as hepatotoxins. Microcystins have many structural variations, yet insufficient information is available on the differences in the cytotoxic potentials among the structural variants. In this study, the cytotoxicities of 16 microcystin variants at concentrations of 0.03–10 μg/mL to primary cultured rat hepatocytes were determined by measuring cellular ATP content, and subsequently determined by their 50% inhibitory concentration (IC₅₀). Differences in the amino acid constituents were associated with differences in cytotoxic potential. [d-Asp³, Z-Dhb⁷] microcystin-LR exhibited the strongest cytotoxicity at IC₅₀ of 0.053 μg/mL among the microcystin variants tested. Furthermore, [d-Asp³, Z-Dhb⁷] microcystin-HtyR was also highly cytotoxic. These results suggest that both d-Asp and Z-Dhb residues are important in determining the cytotoxic potential of microcystin variants.     

Infants’ recognition of their mothers’ faces in facial drawings

This study examined the development of ability to recognize familiar face in drawings in infants aged 6–8 months. In Experiment 1, we investigated infants’ recognition of their mothers’ faces by testing their visual preference for their mother’s face over a stranger’s face under three conditions: photographs, cartoons produced by online software that simplifies and enhances the contours of facial features of line drawings, and veridical line drawings. We found that 7- and 8-month-old infants showed a significant preference for their mother’s face in photographs and cartoons, but not in veridical line drawings. In contrast, 6-month-old infants preferred their mother’s face only in photographs. In Experiment 2, we investigated a visual preference for an upright face over an inverted face for cartoons and veridical line drawings in 6- to 8-month-old infants, finding that infants aged older than 6 months showed the inversion effect in face preference in both cartoons and veridical line drawings. Our results imply that the ability to utilize the enhanced information of a face to recognize familiar faces may develop aged around 7 months of age.     

Early postoperative heparinization reduce hemolysis in patients with HeartMate II devices

Journal of Artificial Organs - Hemolysis is closely related with pump thrombosis and thromboembolic events in patients with continuous flow left ventricular assist devices. We retrospectively...     

Correction to: Intermittent application of external positive pressure helps to preserve organ viability during ex vivo perfusion and culture

Journal of Artificial Organs - article Intermittent application     

Epidermal growth factor receptor (EGFR) mutations in lung cancer: preclinical and clinical data

Lung cancer leads cancer-related mortality worldwide. Non-small-cell lung cancer (NSCLC), the most prevalent subtype of this recalcitrant cancer, is usually diagnosed at advanced stages, and available systemic therapies are mostly palliative. The probing of the NSCLC kinome has identified numerous nonoverlapping driver genomic events, including epidermal growth factor receptor (EGFR) gene mutations. This review provides a synopsis of preclinical and clinical data on EGFR mutated NSCLC and EGFR tyrosine kinase inhibitors (TKIs). Classic somatic EGFR kinase domain mutations (such as L858R and exon 19 deletions) make tumors addicted to their signaling cascades and generate a therapeutic window for the use of ATP-mimetic EGFR TKIs. The latter inhibit these kinases and their downstream effectors, and induce apoptosis in preclinical models. The aforementioned EGFR mutations are stout predictors of response and augmentation of progression-free survival when gefitinib, erlotinib, and afatinib are used for patients with advanced NSCLC. The benefits associated with these EGFR TKIs are limited by the mechanisms of tumor resistance, such as the gatekeeper EGFR-T790M mutation, and bypass activation of signaling cascades. Ongoing preclinical efforts for treating resistance have started to translate into patient care (including clinical trials of the covalent EGFR-T790M TKIs AZD9291 and CO-1686) and hold promise to further boost the median survival of patients with EGFR mutated NSCLC.     

The pathological implications of heart transplantation: Experience with 50 cases in a single center

Heart transplantation started in Japan in 1999. Since then, 50 transplants have been performed at our center. We performed histopathological analyses of the 50 explanted hearts and the post‐transplant biopsy specimens. The median age of recipients was 39 years. The primary diseases before transplant were idiopathic dilated cardiomyopathy in 33 patients (66%), hypertrophic cardiomyopathy in seven (14%), restrictive cardiomyopathy in one, arrhythmogenic right ventricular cardiomyopathy in one, and secondary cardiomyopathy in eight (16%). Before transplantation, 47 patients (94%) had left ventricular assist devices. No severe cardiovascular failure due to allograft rejection occurred. The post‐transplant survival rate was 97.6% at 1 year and 93.1% at 10 years. One recipient was lost to sepsis from myelodysplastic syndrome in the fourth year, one died of multiple organ failure and peritonitis 8 months after transplant. Another patient died of recurrent post‐transplant lymphoproliferative disorders (PTLD). Mild cardiac dysfunction occurred in seven recipients in the early postoperative period. Moderate acute cellular rejection occurred in six patients (12%), and antibody‐mediated rejection occurred in three (6%). The number of heart transplants performed in Japan is very small. However, the outstanding 10‐year survival rate is due to donor evaluation and post‐transplant care resulting in low grade rejection. Pathological evaluation has also greatly contributed to the results.     

s‐Afadin binds more preferentially to the cell adhesion molecules nectins than l‐afadin

l‐Afadin was originally purified from rat brain as an actin filament (F‐actin)‐binding protein that was homologous to the AF‐6 gene product. Concomitantly, s‐afadin that did not show an F‐actin‐binding capability was copurified with l‐afadin. Structurally, s‐afadin lacks the C‐terminal F‐actin‐binding domain but has two short sequences that were not present in l‐afadin. The properties and roles of l‐afadin have intensively been investigated, but those of s‐afadin have poorly been understood. We show here an additional difference in their biochemical properties other than binding to F‐actin between l‐afadin and s‐afadin. Both l‐afadin and s‐afadin bound to nectins, immunoglobulin‐like cell adhesion molecules, whereas s‐afadin more preferentially bound to nectins than l‐afadin. The PDZ domain of l‐afadin and s‐afadin was essential for their binding to nectin‐3. The dilute domain of l‐afadin negatively regulated its binding to nectin‐3, but the deletion of the C‐terminal F‐actin‐binding domain of l‐afadin did not increase the binding of l‐afadin to nectin‐3. These results indicate that the s‐afadin‐specific C‐terminal inserts may be involved in its preference of binding to nectin‐3 and raise the possibility that there are proteins other than nectins that more preferentially bind s‐afadin than l‐afadin.     

Amino acid residues required for Gtr1p‐Gtr2p complex formation and its interactions with the Ego1p‐Ego3p complex and TORC1 components in yeast

The yeast Ras‐like GTPases Gtr1p and Gtr2p form a heterodimer, are implicated in the regulation of TOR complex 1 (TORC1) and play pivotal roles in cell growth. Gtr1p and Gtr2p bind Ego1p and Ego3p, which are tethered to the endosomal and vacuolar membranes where TORC1 functions are regulated through a relay of amino acid signaling interactions. The mechanisms by which Gtr1p and Gtr2p activate TORC1 remain obscure. We probed the interactions of the Gtr1p‐Gtr2p complex with the Ego1p‐Ego3p complex and TORC1 subunits. Mutations in the region (179–220 a.a.) following the nucleotide‐binding region of Gtr1p and Gtr2p abrogated their mutual interaction and resulted in a loss in function, suggesting that complex formation between Gtr1p and Gtr2p was indispensable for TORC1 function. A modified yeast two‐hybrid assay showed that Gtr1p‐Gtr2p complex formation is important for its interaction with the Ego1p‐Ego3p complex. GTP‐bound Gtr1p interacted with the region containing the HEAT repeats of Kog1p and the C‐terminal region of Tco89p. The GTP‐bound Gtr2p suppressed a Kog1p mutation. Our findings indicate that the interactions of the Gtr1p‐Gtr2p complex with the Ego1p‐Ego3p complex and TORC1 components Kog1p and Tco89p play a role in TORC1 function.