[Morphological changes in the retina following one-shot injection of netilmicin sulfate into the vitreous]

Morphological changes of the retina following one-shot injections into the vitreous of netilmicin sulfate were investigated. The concentrations of netilmicin in the vitreous after intravitreal injection showed the curve of y = a/xb, where y is the concentrations in the vitreous body, x in the number of days since injection and a, b are constant. Concentration decreased rapidly after the injection, and almost totally disappeared after one week. Morphologically, the retina showed normal structure following injections of 100 micrograms/0.1ml and 200 micrograms/0.1ml. Following injections of over 500 micrograms/0.1ml, the outer segment of the photoreceptor disappeared and many phagosomes appeared in the retinal pigment epithelium cell. Following one shot injections of over 500 micrograms/0.1ml damage to the photoreceptor and retinal pigment epithelium was demonstrated. The above data suggested that one-shot injection of netilmicin in concentrations of up to 200 micrograms/0.1ml could be mode without retinal damage.

[Serum pepsinogen I level in patients with stomach cancer--its value and limitation in clinical use]

We measured serum pepsinogen I (PG I) levels in 137 stomach cancer patients by the previously described radioimmunoassay and compared them with those of normal cancer-free subjects by a gastric mass survey in a certain workplace. The value and limitations of the measurement of serum PG I level in the diagnosis of stomach cancer were analyzed statistically according to the histology and stage of the disease. The mean serum PG I level of stomach cancer patients was 21.3 micrograms/l [early stage (N = 53): 24.9 micrograms/l; advanced stage (N = 84): 19.2 micrograms/l; well-differentiated (N = 62): 19.5 micrograms/l poorly-differentiated (N = 75): 22.7 micrograms/l]. It was significantly lower than that of the age-matched cancer-free subjects. As to the stage and histology of the disease, early stage poorly-differentiated adenocarcinoma and the same stage well-differentiated adenocarcinoma took the mean serum PG I level of 30.6 micrograms/l (N = 26, p less than 0.05) and 20.2 micrograms/l (N = 27, p less than 0.001). In the advanced stage, they were 19.3 micrograms/l (N = 49, p less than 0.001) and 18.6 micrograms/l (N = 35, p less than 0.001), respectively. Using a cut off point of 25 micrograms/l to separate subjects with stomach cancer, sensitivity was 61% and specificity, 80%. These results suggest a possibility of serological screening of the subjects with stomach cancer and indicate that the measurement of serum PG I level will probably contribute much to the improvement of the effectiveness of a gastric mass survey.

Gastric procathepsin E and progastricsin from guinea pig. Purification, molecular cloning of cDNAs, and characterization of enzymatic properties, with special reference to procathepsin E

Procathepsin E and progastricsin were purified from the gastric mucosa of the guinea pig. They were converted to the active form autocatalytically under acidic conditions. Each active form hydrolyzed protein substrates maximally at around pH 2.5. Pepstatin inhibited cathepsin E very strongly at an equimolar concentration, whereas the inhibition was much weaker for gastricsin. Molecular cloning of the respective cDNAs permitted us to deduce the complete amino acid sequences of their pre-proforms; preprocathepsin E and preprogastricsin consisted of 391 and 394 residues, respectively. Procathepsin E has unique structural and enzymatic features among the aspartic proteinases. Lys at position 37, which is common to various aspartic proteinases and is thought to be important for stabilizing the activation segment, was absent at the corresponding position, as in human procathepsin E. The rate of activation of procathepsin E to cathepsin E is maximal at around pH 4.0. It is very different from the pepsinogens and may be correlated with the absence of Lys37. Native procathepsin E is a dimer, consisting of two monomers covalently bound by a disulfide bridge between 2 Cys37. Interconversion between the dimer and the monomer was reversible and regulated by low concentrations of a reducing reagent. Although the properties of the dimeric and monomeric cathepsins E are quite similar, a marked difference was found between them in terms of their stability in weakly alkaline solution: monomeric cathepsin E was unstable at weakly alkaline pH whereas the dimeric form was stable. The generation of the monomer was thought to be the process leading to inactivation, hence degradation of cathepsin E in vivo.

A paracrine migration-stimulating factor for metastatic tumor cells secreted by mouse hepatic sinusoidal endothelial cells: identification as complement component C3b

Selective malignant cell invasion at secondary sites mediated by organ-specific (paracrine) motility factors may be of importance in preferential organ colonization of metastatic cells. In this study we isolated and examined a migration-stimulating activity present in mouse hepatic sinusoidal endothelial cell-conditioned medium (HSE-CM). HSE-CM contains migration-stimulating activity for highly liver-metastatic (RAW117-H10) and highly lung- and liver-metastatic (RAW117-L17) mouse large cell lymphoma sublines but not for the poorly metastatic parental line (RAW117-P). A migration-stimulating factor for H10 cells was purified from HSE-CM by hydroxylapatite affinity and DEAE anion exchange chromatography, Sephacryl S-200 gel filtration, and preparative native gel electrophoresis. The activity in each of the purification fractions was measured in a Transwell chamber assay using 3-microns diameter pore filters. Upon sodium dodecyl sulfate polyacrylamide gel electrophoresis, the component migrated as a single component of M(r) > 200,000 (nonreducing conditions) or as two components or M(r) approximately 110,000 and approximately 67,000 (reducing conditions). The factor was bound to Concanavalin A-Sepharose but not to heparin- or gelatin-Sepharose affinity columns, induced mainly H10 chemotactic cell activity and some chemokinetic activity, and preferentially stimulated the chemotaxis of liver-colonizing RAW117 sublines (H10 > L17 > P). NH2-terminal amino acid sequence analysis of each subunit indicated that the HSE-CM-derived migration-stimulating factor was a proteolytic fragment of complement component C3. HSE-derived migration-stimulating factors may be important in determining the ability of RAW117 tumor cells to invade and colonize the liver.

Synthetic oligopeptides bearing a common or subtypic determinant of hepatitis B surface antigen

Two determinants of hepatitis B surface Ag (HBsAg), identified by mAb raised against polypeptide components, were characterized immunochemically. One was expressed on HBsAg irrespective of the four major subtypes, i.e., adw, adr, ayw, and ayr, whereas the other was subtypic but not identical to any of d, y, w, and r determinants. The common determinant was generated by a synthetic pentadecapeptide with a sequence of Thr-Thr-Ser-Thr-Gly-Pro-Cys-Lys-Thr-Cys-Thr-Ile-Pro-Ala-Gln representing amino acids 115-129 of the S gene product, and detected invariably in 366 HBsAg samples in sera from asymptomatic carriers in Japan. The activity of the S gene product, as well as the peptide (115-129), to bind with the mAb was not affected by alkylation alone, but was completely lost after reductive alkylation. The antigenic activity was lost when the S gene product was severed between Lys122 and Thr123 by trypsin. A microconformation maintained by the -Cys121-Cys124 bond, therefore, would be required for the common determinant. The other mAb identified an epitope of HBsAg that was mimicked by a synthetic tetradecapeptide with a sequence of Thr-Cys-Thr-Ile-Pro-Ala-Gln-Gly-Thr-Ser-Met-Phe-Pro-Ser, representing amino acids 123-136 of the S gene product. Among 16 HBsAg samples with known S gene sequences, 5 with Ile126 possessed this subtypic determinant, but the remaining 11 with Thr126 did not. The 5 hepatitis B virus genomes encoding the subtypic determinant differed less than 5.6% from each other in the entire nucleotide sequence, but by 8.0% or more from any of the other 11 genomes without the capacity to encode it.

Manganese silicide nanowires on Si(001)

A method for promoting the growth of manganese silicide nanowires on Si(001) at 450 °C is described. The anisotropic surface stress generated by bismuth nanolines blocks the formation of embedded structures and stabilizes the nucleation of manganese silicide islands which grow in a preferred direction, forming nanowires with a band gap of approximately 0.6 eV, matching the reported band gap of MnSi(1.7). This method may also provide a means to form silicide nanowires of other metals where they do not otherwise form.

[Study of Dose Recalculation Method on Overriding Lung Density Using CBCT Image in the Thorax]

It is a useful method for the adaptive radiotherapy (ART) to calculate absorbed dose accurately on the image set taken by on-board cone beam computed tomography (CBCT) attached to linac for image-guided radiation therapy (IGRT). For this purpose, a simple and accurate calculation method is necessary. Several papers report that it is possible to calculate easily and accurately by using several methods of researches in the neck and prostate, but the lung density varies greatly depending on patient thorax condition. In this study, we propose a new dose recalculation method, which is a simple procedure and can achieve accurate dose calculation considered different lung densities in each patient. By using this method, it is possible to calculate exclusive of artifacts in CBCT because of overriding the lung density. The dose error between dose recalculation of the CBCT image and treatment plan agreed within±1%. Therefore, this method is expected to be a useful method for accurate dose calculation with CBCT image for ART.