Relation between mixed venous blood oxygen saturation and cardiac pumping function at the acute phase of myocardial infarction

In this study, we monitored changes in the mixed venous blood oxygen saturation (Sv-O2) level of 45 patients with acute myocardial infarction and compared these results to the traditional parameters. The Sv-O2 level was found to correlate well with the clinical course of patients and their hemodynamic conditions. The mean Sv-O2 level of the group having congestive heart failure (53.3 +/- 8.4%) was found to be statistically lower than those without (69.8 +/- 5.6). Furthermore, patients whose Sv-O2 level was lower than 60% were found to be at greater risk for heart failure and a very high mortality rate. Patients were classified into four subsets according to Forrester's hemodynamic classification; their Sv-O2 levels were 70.7 +/- 4.1% (I: 23 cases), 54.7 +/- 6.9% (II: 8 cases), 55.8 +/- 9.4% (III: 10 cases), and 47.0 +/- 8.0 (IV: 4 cases), respectively. A severe relationship between pulmonary capillary wedge pressure and Sv-O2 having a correlation coefficient of r = -0.64 was observed, and a logarithmic curvilinear relation between cardiac index approximately Sv-O2, stroke volume index approximately Sv-O2 and left ventricular stroke work index approximately Sv-O2 was also evident. When the decrease in the Sv-O2 level was more than 5%, it always showed a significant decrease in the cardiac index. This study suggested tht continuous monitoring of the Sv-O2 level revealed simultaneous changes in the hemodynamic state, which lead to the assistance and aid for treating patients with critical conditions of acute myocardial infarction. In such circumstances, it was noted that the Sv-O2 level should be maintained above 60% in order to stabilize the hemodynamic state.     

Crystal structure of aldoxime dehydratase and its catalytic mechanism involved in carbon-nitrogen triple-bond synthesis

Aldoxime dehydratase (OxdA), which is a unique heme protein, catalyzes the dehydration of an aldoxime to a nitrile even in the presence of water in the reaction mixture. Unlike the utilization of H₂O₂ or O₂ as a mediator of catalysis by other heme-containing enzymes (e.g., P450), OxdA is notable for the direct binding of a substrate to the heme iron. Here, we determined the crystal structure of OxdA. We then constructed OxdA mutants in which each of the polar amino acids lying within ∼6 Å of the iron atom of the heme was converted to alanine. Among the purified mutant OxdAs, S219A had completely lost and R178A exhibited a reduction in the activity. Together with this finding, the crystal structural analysis of OxdA and spectroscopic and electrostatic potential analyses of the wild-type and mutant OxdAs suggest that S219 plays a key role in the catalysis, forming a hydrogen bond with the substrate. Based on the spatial arrangement of the OxdA active site and the results of a series of mutagenesis experiments, we propose the detailed catalytic mechanism of general aldoxime dehydratases: (i) S219 stabilizes the hydroxy group of the substrate to increase its basicity; (ii) H320 acts as an acid-base catalyst; and (iii) R178 stabilizes the heme, and would donate a proton to and accept one from H320.     

Lactone-ring-cleaving enzyme: Genetic analysis, novel RNA editing, and evolutionary implications

A lactonohydrolase from Fusarium oxysporum AKU 3702 is an enzyme catalyzing the hydrolysis of aldonate lactones to the corresponding aldonic acids. The amino acid sequences of the NH₂ terminus and internal peptide fragments of the enzyme were determined to prepare synthetic oligonucleotides as primers for the PCR. An approximate 1,000-base genomic DNA fragment thus amplified was used as the probe to clone both genomic DNA and cDNA for the enzyme. The lactonohydrolase genomic gene consists of six exons separated by five short introns. A novel type of RNA editing, in which lactonohydrolase mRNA included the insertion of guanosine and cytidine residues, was observed. The predicted amino acid sequence of the cloned lactonohydrolase cDNA showed significant similarity to those of the gluconolactonase from Zymomonas mobilis, and paraoxonases from human and rabbit, forming a unique superfamily consisting of C-O cleaving enzymes and P-O cleaving enzymes. Lactonohydrolase was expressed under the control of the lac promoter in Escherichia coli.     

Primary mucosa-associated lymphoid tissue-type lymphoma arising in the kidney

Abstract:   We report a case of primary low-grade lymphoma of mucosa-associated lymphoid tissue (MALT) arising from the kidney in a 30-year-old man with an abdominal mass in the right flank detected by ultrasonography. Radical nephrectomy was performed under a preliminary diagnosis of renal cell carcinoma. The final histological diagnosis was MALT-type lymphoma. To the best of our knowledge, only five reports of primary MALT-type lymphoma in the kidney have been published in the literature so far. All cases were surgically treated and only one case went on to chemotherapy postoperatively.