Genetic Variation in VP7 Gene of Human Rotavirus Serotype 2 (G2 Type) Isolated in Japan,China, and Pakistan

Sequence analysis of the gene encoding the major neutralization glycoprotein (VP7) was performed on sixteen human isolates of serotype 2 of rotavirus in Japan, China, and Pakistan and their genetic variations were examined. Comparative studies of their nucleotide and deduced amino acid sequences between the sixteen isolates and the HU5 strain revealed an overall homology of more than 94%. A higher degree of homology in nucleotides was observed among the sixteen isolates than between HU5 and the isolates. A total of thirteen amino acid residues frequently converted to another amino acid. Out of the thirteen, five amino acid residues belonging to the major neutralizing epitope regions (C, E, and F in this communication) converted frequently. From the amino acid sequences three subtypes, subtype 1, subtype 2, and intermediate, were suggested to be classified as previously reported for serotype 1 (Xin et al, Virology, 1993, 197: 813-816).     

Prevention of Vascular Graft Infection by Sisomicin Incorporated into Fibrin Glue

To examine the efficacy of sisomicin (SISO) incorporated into fibrin glue (FG) for the prevention of graft infection in animal models, the susceptibility to infection of Dacron grafts (control) and SISO-FG Dacron grafts following the inoculation of Staphylococcus aureus or S. epidermidis was compared. The results showed that SISO-FG Dacron grafts displayed resistance to graft infection.     

Three Antigenic Regions in p17 of Human Immunodeficiency Virus Type 1 (HIV-1) Revealed by Mouse Monoclonal Antibodies and Human Antibodies in HIV-1 Carrier Sera

We investigated the murine antibody response to recombinant p17 (rp17) of human immunodeficiency virus type 1 (HIV-1) and the human antibody response directed to p17 in HIV-1 infection. Three large peptides covering residues 12-29, 53-87 and 87-115 of p17 were synthesized. The cysteine residues 57 and 87 of peptide 53-87 were reoxidized to form a disulfide bridge. Eighteen out of 19 murine monoclonal anti-rp17 antibodies had relatively high affinities (K_A = 1.9 × 10⁵?1.4 × 10⁸ M^?1) with one of the 3 p17 peptides in the liquid phase. Each monoclonal antibody reacted only with one particular peptide and had no reactivity with the other 2 p17 peptides. All the monoclonal antibodies reacted with rp17 in the liquid phase with a reasonable degree of affinity (K_A = 2.0 × 10⁵?1.8 × 10⁷ M^?1). Four HIV-1 carrier sera, which were positive in ELISA using rp17 as the antigen, reacted positively in an ELISA using 3 p17 peptides which were used to titrate murine monoclonal antibodies. Murine monoclonal antibodies having specificity for the 3 p17 peptides stained live HIV-1-infected cells by means of indirect membrane immunofluorescence, irrespective of their specificity. This suggests that the various portions of p17 (at least 3 regions of p17) were exposed on the surface of live infected cells, probably as short polypeptide chains.     

Isolation of Cytopathic Small Round Virus (Aichi Virus) from Pakistani Children and Japanese Travelers from Southeast Asia

Aichi virus was isolated in Vero cells from 5 (2.3%) of 222 Pakistani children with gastroenteritis but none was found in 91 healthy children. Aichi virus was also isolated from 5 (0.7%) of 722 Japanese travelers returned from tours to Southeast Asian countries and complained of gastrointestinal symptoms at the quarantine station of Nagoya International Airport in Japan. Of 5 Japanese travelers, 3 were returning from Indonesia, and 2 from Thailand or Malaysia. These results indicate that Aichi virus or a similar agent is endemic in Southeast Asian countries and is a cause of gastrointestinal symptoms in children in these areas or in Japanese travelers who visit there.     

Self-organization of the velocity selectivity of a directionally selective neural network

We first present a mathematical analysis of the relation between the parameters and the behavior of the basic module in the proposed neural network model for visual motion detection. Based on the analytical results, a learning rule is put forth that can develop velocity selectivity of directionally selective cells in the basic module. The learning rule is furthermore introduced into the total model called a mass model, which is constructed with many basic modules. Numerical simulation results showed that each basic module in the mass model learned in a self-organizing manner to acquire selectivity for the velocity of an input stimulus. The proposed learning rule would be plausible in the actual nervous system in that it is simple and can be described with only local information.     

Immunocytochemical localization of L-α-hydroxyacid oxidase in dense bar of dumb-bell-shaped peroxisomes of monkey kidney

Localization of the B of L-hydroxyacid oxidase (HOX-B) in monkey kidney peroxisomes was investigated by immunoelectron microscopic techniques. Kidneys of Japanese monkeys,Macaca fuscata, were fixed with 4% paraformaldehyde+0.25% glutaraldehyde and embedded in LR White resin. Thin sections were stained for HOX-B and catalase by the immunogold technique. HOX-B was localized in the marginal plates of normal peroxisomes and the dense bar of dumb-bellshaped peroxisomes. Catalase was detected in the matrix of normal peroxisomes and in the terminal dilatations of dumb-bell-shaped peroxisomes. There were no gold particles indicating presence of catalase associated with the marginal plates or with the dense bars. Immunoblot analysis of monkey kidney homogenate showed that HOX-B has a molecular mass of 42 kDa that was slightly larger than that of rat kidney HOX-B (39 kDa). The results show that the dense bar of dumb-bell-shaped peroxisomes in monkey kidney is composed of at least HOX-B and is a variation of the marginal plates.     

Electron microscopic study of endogenous peroxidase activity in human liver macrophages

We evaluated the conditions of fixation for ultrastructurally demonstrating the endogenous peroxidase (PO) activity of macrophages in biopsied human liver. The application of microwaving and immersion fixation with tannic acid and aldehydes allowed excellent visualization of PO activity in the nuclear envelope (NE), rough endoplasmic reticulum (rER), and cytoplasmic granules (CG), with good preservation of cellular ultrastructures. The macrophages with PO activity showed one of the following five patterns of PO localization: positive in both the NE and rER but negative in the CG (type 1); negative in both the NE and rER but positive in the CG (type 2); negative in the NE but positive in both the rER and CG (type 3); positive in all three (type 4); PO negative (type 5). The type 1 cells resembled typical Kupffer cells, type 2 cells monocytes, and type 3 and 4 cells the exudate-resident macrophages considered to be a transitional form between exudate and resident macrophages. Type 5 cells may also be a transitional form between the exudate and resident macrophage, or an end-stage macrophage derived from exudate macrophages which have lost their PO activity. Tannic-acid-aldehyde immersion fixation with microwaving may be a useful method in the study of the PO activities of macrophages in biopsied human liver specimens.     

Redistribution and fate of colchicine-induced alkaline phosphatase in rat hepatocytes: possible formation of autophagosomes whose membrane is derived from excess plasma membrane

The redistribution and fate of colchicine-induced alkaline phosphatase (ALPase) in rat hepatocytes were investigated by electron microscopic enzyme cytochemistry and biochemistry. ALPase activity markedly increased in rat hepatocytes after colchicine treatment (2.0 mg/kg body weight, intraperitoneal injection). At 20–24 h after colchicine treatment, the liver showed the highest activity of ALPase. Thereafter, ALPase activity decreased and returned to normal levels at 48 h. In normal hepatocytes from control rats, ALPase activity was seen only on the bile canalicular membrane. However, at 20–24 h after colchicine treatment, colchicine-induced ALPase was redistributed in the sinusoidal and lateral (basolateral) membranes as well as in the bile canalicular membrane. At 30–36 h after colchicine treatment, ALPase activity on the basolateral membrane gradually decreased. In contrast, ALPase in the bile canalicular membrane increased along with the enlargement of bile canaliculi, suggesting that ALPase in the basolateral membrane had been transported to the bile canalicular membrane. Furthermore, ALPase-positive vesicles, cisternae and autophagosome-like structures were frequently seen in the cytoplasm. ALPase was also positive in some lysosomal membranes. ALPase in hepatocytes at 48 h after colchicine treatment returned to almost the same location as in control hepatocytes. Altogether, it is suggested that excessively induced ALPase is at least partially retrieved by invagination of the bile canalicular membrane and then transported to lysosomes for degradation. In addition, this study indicates that excess plasma membrane might be a possible origin of autophagosomal membrane.     

Isolation of the putative structural gene for the lysine-arginine-cleaving endopeptidase required for processing of yeast prepro-alpha-factor

S. cerevisiae kex2 mutants are defective for the production of two biologically active secreted peptides: killer toxin and the mating pheromone, alpha-factor. Both molecules are excised from larger precursor polypeptides. In normal cells, the alpha-factor precursor is core-glycosylated and proteolytically processed intracellularly. In kex2 mutants, however, prepro-alpha-factor is not proteolytically cleaved and is secreted in a highly glycosylated form. All kex2 mutants examined (three independent alleles) lack a Zn++-sensitive membrane-associated endopeptidase with specificity for cleaving on the carboxyl side of a pair of basic residues. Absence of this activity cosegregates with the other phenotypes of a kex2 lesion in genetic crosses. The normal KEX2 gene was isolated by complementation of three of the phenotypes conferred by the kex2-1 mutation. The cloned DNA, either on a multicopy plasmid or integrated into the genome, restores both enzymatic activity in vitro and the normal pattern of proteolytic processing and glycosylation of prepro-alpha-factor in vivo. Gene dosage effects suggest that KEX2 is the structural gene for the endopeptidase.     

Different metastatic modes of malignant melanoma implanted in the ear of young and old mice

Summary An attempt has been made to determine (a) whether aging plays an important role in resistance against metastasis and (b) whether dithiothreitol, an effective in vitro mitogenic potentiator of splenic cells of young and old mice, can modulate the occurrence of pulmonary metastasis. B16-F10 melanoma cells were injected into the outer ear of young and old female C57BL/6 mice; and the growth of the primary tumor, the palpable size of the cervical lymph node, and the number of lung metastases were then determined at various intervals. The ear was amputated when the primary tumor reached 4 mm in mean diameter. The following results were obtained. (a) The growth rate of the primary tumor in young mice is comparable to that in old mice. (b) Enlargement of the cervical lymph node occurs earlier in old than in young mice. (c) Old mice are more vulnerable to pulmonary metastases, but small metastasized pulmonary colonies are more prominent in old than in young mice. (d) Dithiothreitol (100 g) injected every 2 days after the inoculation of tumor cells is effective in reducing the incidence of pulmonary metastases in old mice.