Migration and turnover of entero-endocrine and caveolated cells in the epithelium of the descending colon, as shown by radioautography after continuous infusion of 3H-thymidine into mice

Adult male mice were given a continuous infusion of about 0.5 muCi of 3H-thymidine per gram body weight per day for periods varying from 1 to 60 days. Semithin sections of descending colon were cut from/plastic-embedded blocks and stained by a method combining silver impregnation and iron hematoxylin, by which argentaffin entero-endocrine cells and caveolated cells could be identified. From radioautographs, the labeling index of these cells was determined. One to three days after the beginning of 3H-thymidine infusion, label is observed in some of the stained entero-endocrine cells in the bottom of the crypts; the apices of these cells reach the crypt lumen and are joined to neighboring cells by terminal bars (junctional complexes). After five to seven days, labeled entero-endocrine cells are seen on the sides of the crypts, where their base stretches along the basement membrane and their apex has lost its terminal bar connections to neighboring cells. Finally, by 13 and 24 days, labeled cells are observed within the epithelium at the mucosal surface. The turnover time, which is taken to be equal to the mean time required for migration from site of origin to site of loss on the mucosal surface, has been estimated at 23.3 days. This is much longer than the 4.6 days required by the two main cell types of the epithelium -- vacuolated-columnar and mucous cells -- to travel the same route. It is likely that, after entero-endocrine cells lose their terminal bar attachment to other epithelial cells, they migrate independently and very slowly. Labeled caveolated cells are first seen in the crypt bottom one day after the beginning of 3H-thymidine infusion. By three to five days, they are on the sides of the crypts; their base is stretched along the basement membrane, but their apex retains its attachment to neighboring cells by terminal bars. By seven days, labeled caveolated cells are on the mucosal surface. Their turnover time has been assessed at 8.2 days. This is, again, longer than for the two main types to which they are bound by terminal bars throughout migration. The discrepancy is explained by the caveolated cells arising deeper in the crypts than most vacuolated-columnar and mucous cells.     

Glutamine Synthetase of the Human Brain: Purification and Characterization

Glutamine synthetase (GS) isolated from human brain formed a single band on sodium dodecyl sulfate-polyacrylamide gel with a molecular weight of 44,000. The enzyme had a specific activity of 179.2 U/mg protein when assayed by measuring the rate of the formation of gamma-glutamylhydroxamate using hydroxylamine as a substrate. In the presence of manganese ions, the relative activity of human brain GS was much lower than that of the sheep brain enzyme. The suppression of activity by increasing the ADP concentration, however, was less marked in the human enzyme than that in the sheep enzyme. Antibodies were raised in rabbits against the purified enzyme. The double-immunodiffusion technique disclosed cross-reactivities among GSs isolated from human, sheep, and rat brains, but the enzymes were not immunologically identical. Immunohistochemically, GS was localized in the cytoplasm of astrocytes in the human and rat brains and in pericentral hepatocytes of the liver.     

Effect of roasting on ochratoxin A level in green coffee beans inoculated with Aspergillus ochraceus

The heat stability of ochratoxin A in green coffee beans inoculated with Aspergillus ochraceus was studied. Heat treatment (roasting) at 200 °C for 10 or 20 min reduced the levels of ochratoxin A by only 0–12% in the dried whole beans. Almost all of the ochratoxin A was infused into the coffee decoction when the roasted samples were ground and extracted with boiling water. Therefore, the reduction of ochratoxin A concentration of contaminated coffee beans by roasting under these conditions is ineffective.     

Molecular cloning and sequence analysis of cDNA for human hepatocyte growth factor

Amino acid sequences of four peptide fragments of human hepatocyte growth factor purified from the plasma of patients with fulminant hepatic failure were determined. Based on the amino acid sequence of one of the fragments, two oligodeoxyribonucleotide mixtures were synthesized and used to screen a human placenta cDNA library. On the screening, two overlapping cDNA clones for human hepatocyte growth factor were isolated and the nucleotide sequence of the cDNA was determined. The entire primary structure of the protein was deduced from the sequence. The protein consists of 728 amino acid residues, including a possible signal peptide at the N-terminus. The sequence revealed that the heavy and light chains which comprise the protein are encoded by the same mRNA and are produced from a common translation product by proteolytic processing.     

Phosphorus-31 magnetic resonance spectroscopy of forearm flexor muscles in student rowers using an exercise protocol adjusted for differences in cross-sectional muscle area

To assess exercise energy metabolism of forearm flexor muscles in rowers, six male student rowers and six control subjects matched for age and sex were studied using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Firstly, to adjust for the effect of differences in cross-sectional muscle area, the maximal cross-sectional area (CSAmax) of the forearm flexor muscles was estimated in each individual using magnetic resonance imaging. Multistage exercise was then carried out with an initial energy production of 1 J.cm-2 CSAmax for 1 min and an increment of 1 J.cm-2 CSAmax every minute to the point of muscle exhaustion. A series of measurements of 31P-MRS were performed every minute. The CSAmax was significantly greater in the student rowers than in the control subjects [19.8 (SD 2.2) vs 17.1 (SD 1.2) cm2, P less than 0.05]. The absolute maximal exercise intensity (J.min-1) was greater in the rowers than in the control subjects. However, the maximal exercise intensity per unit of muscle cross sectional area (J.min-1.cm-2) was not significantly different between the two groups. During mild to moderate exercise intensities, a decrease in phosphocreatine and an increase in inorganic phosphate before the onset of acidosis were significantly less in the rowers, indicating a requirement of less adenosine 5'-diphosphate to drive adenosine 5'-triphosphate production. The onset of acidosis was also significantly delayed in the rowers. No difference was observed in forearm blood flow between the two groups at the same exercise intensity (J.min-1.cm-2).(ABSTRACT TRUNCATED AT 250 WORDS)     

Fine structural and immunohistochemical studies of goat adenohypophysial cells

Summary The fine structure of each type of anterior pituitary cell in the male goat was studied through the application of a superimposition technique in which adjacent thick sections were used to identify individual cells beforehand by light-microscopic immunohistochemistry. A cone of the pars intermedia protrudes into the pars anterior, being surrounded by the narrow pituitary cleft; the immunohistochemical appearances of the cells forming the cone resemble those of the pars anterior. Several follicles appear in the pars anterior. Ultrastructurally GH cells resemble prolactin cells. The secretory granules of both types are spherical; the diameter of the former is about 340 nm, whereas that of the latter is about 440 nm. ACTH cells are polygonal in shape with secretory granules, about 180 nm in diameter, scattered throughout the cytoplasm. TSH cells, which are spherical in shape, contain the smallest secretory granules, 150 nm in diameter. The highly electron-dense LH cells contain numerous secretory granules about 210 nm in diameter. Their nuclei are irregular with incisures. Thus, the anterior pituitary cells of the goat are ultrastructurally characteristic and species-specific.     

Immunoreactive glucagon in the vascular walls of the rat

We detected immunohistochemically immunoreactive glucagon (IRG) in the smooth muscle of blood vessels and the myoepithelial cell of sweat glands of rats using two antisera against pancreatic glucagon; OAL-123 and 30K. The content of IRG in the blood vessels was found to be 320-1, 270 pg per g wet tissue weight. Filtration of the extracted IRG through a Bio Gel P-30 column yielded a single peak of IRG at 3,500 daltons, the same elution volume of pancreatic glucagon. These findings suggest that the blood vessels of the rats is one of the extrapancreatic sources of IRG in plasma, although physiological role of the IRG is not known.     

Production of (R)-1-phenylethanol through enantioselective oxidation of (S)-isomer from their racemic mixture by Pachysolen tannophilus IFO 1007

Summary Stereoselective oxidation of (S)-isomer of rac-1-phenylethanol (1-PA) by the yeast Pachysolen tannophilus IFO 1007 immobilized into calcium-alginate gels was investigated to produce (R)-isomer. Continuous production of (R)-isomer was accomplished for more than 80 h with an enantiomeric excess of > 90% using a bioreactor of a fluidized-bed type.     

Controlled release of adeno-associated virus from alginate hydrogel microbeads with enhanced sensitivity to ultrasound

Adeno-associated virus (AAV)-based gene therapy holds promise as a fundamental treatment for genetic disorders. For clinical applications, it is necessary to control AAV release timing to avoid an immune response to AAV. Here we propose an ultrasound (US)-triggered on-demand AAV release system using alginate hydrogel microbeads (AHMs) with a release enhancer. By using a centrifuge-based microdroplet shooting device, the AHMs encapsulating AAV with tungsten microparticles (W-MPs) are fabricated. Since W-MPs work as release enhancers, the AHMs have high sensitivity to the US with localized variation in acoustic impedance for improving the release of AAV. Furthermore, AHMs were coated with poly-l -lysine (PLL) to adjust the release of AAV. By applying US to the AAV encapsulating AHMs with W-MPs, the AAV was released on demand, and gene transfection to cells by AAV was confirmed without loss of AAV activity. This proposed US-triggered AAV release system expands methodological possibilities in gene therapy.