Enzymatic resolution of planar chiral ferrocene derivatives

Racemic 3-methyl, 2-ethyl, 2-bromo, and 2-trimethylsilyl derivatives of formylferrocene were kinetically resolved by enantioselective reduction with a fermenting baker's yeast. Moreover, 2-methyl, 3-methyl, 2-ethyl, 2-bromo, and 2-trimethylsilyl derivatives of hydroxymethylferrocene were optically resolved with lipases by transesterification using vinyl esters.     

Structure and formation process of (K,Na)-clinoptilolite

In order to synthesize (K,Na)-clinoptilolite, a (K,Na)-aluminosilicate slurry with a seed crystal was stirred at 30 °C for 4 days and then hydrothermally treated under homogeneous mixing conditions at 120 °C for 14 days. The Si/Al:(Na+K)/Si:K/(Na+K):H₂O/Al molar ratio of the starting materials was 6.0:0.42:0.5:52.5. The formation process of (K,Na)-clinoptilolite was investigated by a variety of techniques. When the materials were hydrothermally treated up to 6 days, amorphous (K,Na)-aluminosilicate was formed. After the hydrothermal treatment for 8 days, irregular particles due to the amorphous (K,Na)-aluminosilicate disappeared and plate-like particles of (K,Na)-clinoptilolite were formed, indicating that the amorphous aluminosilicate crystallized as clinoptilolite. In addition, (Na+K)/Al molar ratio in the materials varied from 1.2 to 1.0, accompanying the decrease of cation exchange capacity. During the crystallization, the wavenumber of external linkages of TO bonds shifted to higher values, implying that the SiOSi and SiOAl bonds were formed.     

Hemodynamic disturbances in cerebral ischemia: correlation between positron emission tomographic and angiographic findings

Proper treatment of ischemic stroke requires better understanding of cerebral hemodynamic changes. The hemodynamic changes associated with ischemia were measured using positron emission tomography and related to angiographic findings in the subacute and chronic stages of 17 ischemia patients who showed symptoms of main trunk stenosis of the internal carotid artery system. The hemodynamic factors, cerebral blood flow, cerebral blood volume, cerebral metabolic rate for oxygen, oxygen extraction fraction, and flow/volume ratio, were measured in regions of interest determined from the angiographic stenosis (over 50%) and compared in each stage. The cerebral blood flow and flow/volume ratio in the territory downstream of the main trunk stenosis and cerebral metabolic rate for oxygen in the whole cortex were decreased in the subacute stage. In the chronic stage, cerebral blood flow and flow/volume ratio decreased mainly in borderzone areas.     

Specific induction of hepatocellular adenomas by transplacental administration of ENU in the tsc2 gene mutant (Eker) rat

Recombinant human m-calpain was produced in a soluble form at a level of 20 mg/liter of Sf-9 cell culture by the coexpression of recombinant human m-calpain large (m80K) and small (30K) subunits using a baculovirus expression system. The expressed m-calpain was purified by sequential column chromatographies on DEAE-Toyopearl, gel-filtration, and Mono Q by the same method used to purify native m-calpain. The recombinant m-calpain had a specific activity of 691 U/mg and a Ka value (Ca2+ requirement for 50% caseinolysis activity) of 0.4 mM, which are essentially identical to those of native rabbit m-calpain. A mutant m-calpain large subunit, m-C105S-80K, where the active-site cysteine-105 is converted to serine by site-directed mutagenesis, was coexpressed with 30K in Sf-9 cells, purified, and characterized. m-C105S-calpain does not degrade casein nor an artificial tetra-peptide substrate, succinyl-Leu-Leu-Val-Tyr-MCA. Further, it shows no autolytic activity with Ca2+. This is the first report of the large-scale production of a fully active m-calpain species in the baculovirus system.     

Correlation between relative number of circulating low-density hepatitis C virus particles and disease activity in patients with chronic hepatitis C

Hepatitis C virus (HCV) circulates as particles having differing buoyant densities. Changes in the relative proportions of virus particles of different densities were examined in 19 patients with chronic hepatitis C: 6 without (group A) and 13 with (group B) abnormal serum alanine aminotransferase (ALT) levels. High- and low-density virus particles were separated by differential flotation centrifugation. The numbers of high-density particles consistently exceeded that of low-density particles in all patients in group A, whereas the titers of both types of particles were the same at least once in 7 of 10 patients sampled at two time points in group B. The ALT level significantly increased <2 months later (P < 0.05) when the titers of both types of particles were the same in patients in group B. Thus, we found a correlation between the relative numbers of circulating low-density HCV particles and disease activity in chronic hepatitis C patients.     

Knudson's "two-hit" hypothesis in familial cancer syndromes

Cancer is a heritable disorder of somatic cells. Environment and hereditary both operate in the origin of human cancer. Hereditary cancer is rare, but it has served as a useful model in the understanding of carcinogenesis. A number of cancer genes have been identified by the study of hereditary cancers and implicated in sporadic forms of the same tumors. In this article, I reviewed Knudson's famous "two-hit" hypothesis of tumor suppression.