Sequences of cDNAs for human salivary and pancreatic α-amylases

The nucleotide sequences of the cloned human salivary and pancreatic α-amylase cDNAs correspond to the continuous mRNA sequences of 1768 and 1566 nucleotides, respectively. These include all of the amino acid coding regions. Salivary cDNA contains 200 bp in the 5′-noncoding region and 32 in the 3′-noncoding region. Pancreatic cDNA contains 3 and 27 bp of 5′- and 3′-noncoding regions, respectively. The nucleotide sequence humology of the two cDNAs is 96% in the coding region, and the predicted amino acid sequences are 94% homologous.Comparison of the sequences of human α-amylase cDNAs with those previously obtained for mouse α-amylase genes (Hagenbuchle et al., 1980; Schibler et al., 1982) showed the possibility of gene conversion between the two genes of human α-amylase.     

Aggregatibacter actinomycetemcomitans induces detachment and death of human gingival epithelial cells and fibroblasts via elastase release following leukotoxin‐dependent neutrophil lysis

Aggregatibacter actinomycetemcomitans is considered to be associated with periodontitis. Leukotoxin (LtxA), which destroys leukocytes in humans, is one of this bacterium's major virulence factors. Amounts of neutrophil elastase (NE), which is normally localized in the cytoplasm of neutrophils, are reportedly increased in the saliva of patients with periodontitis. However, the mechanism by which NE is released from human neutrophils and the role of NE in periodontitis is unclear. In the present study, it was hypothesized that LtxA induces NE release from human neutrophils, which subsequently causes the breakdown of periodontal tissues. LtxA‐treatment did not induce significant cytotoxicity against human gingival epithelial cells (HGECs) or human gingival fibroblasts (HGFs). However, it did induce significant cytotoxicity against human neutrophils, leading to NE release. Furthermore, NE and the supernatant from LtxA‐treated human neutrophils induced detachment and death of HGECs and HGFs, these effects being inhibited by administration of an NE inhibitor, sivelestat. The present results suggest that LtxA mediates human neutrophil lysis and induces the subsequent release of NE, which eventually results in detachment and death of HGECs and HGFs. Thus, LtxA‐induced release of NE could cause breakdown of periodontal tissue and thereby exacerbate periodontitis.     

Existence of a Novel Hemagglutinin Having No Protease Activity in Vibrio mimicus

The protease elaborated by Vibrio mimicus is known to possess hemagglutinating ability to chicken erythrocytes, the well-known HA/protease. A non-protease hemagglutinin (HA) with strong agglutinating ability towards rabbit erythrocytes was obtained from 32 hr culture supernatant of a pathogenic environmental strain of V. mimicus. This HA (V. mimicus HA: VMHA) appeared stable at relatively higher temperature and agglutinated the erythrocytes from rabbit, guinea pig and mouse but not the erythrocytes from chicken, bovine, horse and sheep. Simple sugars, metal ions and chelating agents failed to inhibit the activity of VMHA. The activity of VMHA was found to be sensitive to digestion by proteolytic enzymes including HA/protease. These results provide evidence for the existence of novel HA other than HA/protease in V. mimicus.     

Purification and characterization of thymidylate synthetase from rat regenerating liver

Thymidylate synthetase (EC 2.1.1.45) from rat regenerating liver has been purified over 5000-fold to apparent homogeneity by a procedure involving two affinity methods. Molecular weight of the native enzyme was found to be about 68,000, as determined by gel filtration. Electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate yielded a single band of molecular weight of 35,000, suggesting that thymidylate synthetase is a dimer of very similar or identical subunits. The Michaelis constants for deoxyuridylate (dUMP) and (+/-)L-5,10-methylenetetrahydrofolate are 6.8 microM and 65 microM, respectively. Reaction kinetics and product inhibition studies reveal the enzymatic mechanism to be ordered sequential. 5-Fluoro-dUMP, halogenated analog of the nucleotide substrate is a competitive inhibitor of the enzyme, with an apparent Ki value of 5 nM. Amethopterin, analog of the cofactor is also a competitive inhibitor with an apparent Ki value of 23 microM.     

Effect of lard and corn oil intake on serum lipids in young men

An experimental diet with lard (30 g/day for 7 days) and corn oil (30 g/day for 7 days) on high carbohydrate (basal diet) was given to four healthy Japanese young men and the effect of diets containing different fat on serum lipids was examined. Serum total cholesterol was increased significantly from a basal diet of 106 +/- 23 to 141 +/- 26 mg/dl on lard diet, and then decreased significantly (p less than 0.05) to 111 +/- 22 mg/dl on corn oil diet. Serum triglycerides increased significantly (p less than 0.01) from 66 +/- 38 to 173 +/- 32 mg/dl on basal diet. Serum HDL-cholesterol was decreased significantly (p less than 0.01) from 41.9 +/- 1.6 to 31.2 +/- 3.8 mg/dl on lard diet and increased significantly (p less than 0.05) to 41.9 +/- 4.6 mg/dl on corn oil diet. Serum HDL-cholesterol fraction was decreased significantly (p less than 0.01) from 41.6 +/- 4.9 to 28.1 +/- 3.2% on basal diets, but increased significantly (p less than 0.05) to 44.3 +/- 3.1% on lard diet, and then decreased to 36.3 +/- 2.5% on corn oil diet. Serum HDL phospholipid fraction decreased significantly (p less than 0.05) from 62.5 +/- 6.7 to 50.7 +/- 1.8% on basal diet and increased significantly (p less than 0.05) to 60.4 +/- 1.0% on lard and corn oil diet. Serum phospholipids did not change by experimental diets. It is concluded that lard and corn oil have different and specific roles in lipid metabolism.     

Serodiagnosis of Streptococcus pneumoniae infection in guinea pigs by an enzyme-linked immunosorbent assay

Guineapig antibodies to Streptococcus pneumoniae (SPN) serotype 19F were detected by an enzyme-linked immunosorbent assay using a simple procedure. In experimentally infected hosts, antibody was detectable as early as 2 to 3 weeks after infection, and high titres were maintained for a long period. Antibodies higher than 1:64 were regarded as specific. In a field study, high antibody titres were shown in SPN enzootic colonies in contrast to negative or low antibody titres in a majority of the animals from non-enzootic and SPF colonies.     

Occurrence of unusual heterogeneous lipid-containing granule-storing cells in the main excretory duct epithelium of the male mouse submandibular gland

Summary The fine structure of the main excretory duct epithelium of the male mouse submandibular glands was investigated by scanning and transmission electron microscopy. Three principal cell-types were observed: type I and II, and basal cells. This epithelium was characterized by the presence of intercellular canaliculi. Type-I cells were the most numerous. They had an abundance of mitochondria, well-developed Golgi apparatus, a few electron-lucent lipid-containing granules and poorly developed basal infoldings. These cells were also characterized by many glycogen granules throughout the cytoplasm and abundant smooth endoplasmic reticulum in the apical cytoplasm. Type-II cells were the second most numerous. Their most characteristic feature was the presence of abundant heterogeneous lipid-containing granules having acid phosphatase activity at the periphery. They were concentrated in the infra- and supranuclear cytoplasm. The granules may be derived from mitochondrial transformation and seem to be a special kind of secondary autolysosome. Type-II cells also contained abundant mitochondria throughout the cytoplasm, much smooth endoplasmic reticulum in the apical cytoplasm, a well developed Golgi apparatus adjacent to the heterogeneous lipid-containing granules and no basal infoldings. Basal cells were situated adjacent to the basal lamina. They had a large nucleus and the cytoplasm was filled with glycogen granules.     

Maternal care in the red-headed spruce web-spinning sawfly,Cephalcia isshikii (Hymenoptera: Pamphiliidae)

We describe oviposition and maternal behavior in the sawfly Cephalcia isshikiiand examine the adaptive significance of this behavior. Females deposited eggs in a single but loose cluster on needles of terminal twigs of spruces, Piceaspp., and remained with the eggs usually on the underside of the twig facing toward the tip. The female attended her eggs until death without taking food but did not follow the first-instar larvae that moved from natal needles even if she survived until then. When the female was disturbed, she usually moved toward the source and attempted to bite it. Though at much lower frequencies, this aggressive behavior was also observed in gravid females and even in males. Field observations and female removal experiments indicated that the female enhanced the survival of the eggs through the reduction of arthropod prédation.