The diagnostic accuracy of a solitary pulmonary nodule, using thin-section high resolution CT: a solitary pulmonary nodule by HRCT.

A solitary pulmonary nodule (SPN) less than 2 cm in diameter of 60 patients was evaluated with thin-section, high-resolution computed tomography (HRCT). The presence of an irregular margin, speculation, convergence of the surrounding structure, an air bronchogram and the involvement of more than 3 vessels was observed more frequently in malignant nodules than in benign nodules. When one point was given for each finding, the mean total scores of each histologic type were as follows; adenocarcinoma; 2.7, squamous cell carcinoma; 2.5, benign tumor; 0.3, tuberculosis; 1.3, pneumonia; 2.0. When SPNs were classified by the total scores, the SPNs with higher scores (> or = 3) included 18 of 33 (56%) malignant lesions and only 2 of 28 (7%) benign lesions. This means that sensitivity and specificity in the diagnosis of malignancy in the SPNs with high scores were 56% and 93%, respectively. These observations suggest that SPNs with a score higher than 3 points would be highly suspicious for malignancy but the number of such SPNs is rather limited. Therefore, more sophisticated methods may be necessary to better differentiate between malignant and benign SPNs.

Enzyme flexibility: a new concept in recognition of hydrophobic substrates.

The mechanism of recognition of hydrophobic substrates was investigated using Escherichia coli aspartate aminotransferase (AspAT), E. coli aromatic amino acid aminotransferase (AroAT), and their chimeric enzyme (DY18). Surprisingly, broad substrate specificity was observed in the reaction of aminotransferases with hydrophobic substrates. The catalytic efficiency increased with an increase in the side chain length of straight or branched-terminal aliphatic substrates. The straight-chain substrates catalysed with maximal efficiency were the 7-carbon substrate in the case of AspAT and the 8-carbon substrate for AroAT and DY18. Consecutive addition of single methylene groups to the substrate had a constant effect on the stabilization energy of the transition state relative to the unbound state. The dependency of binding energy on each methylene group is usually interpreted as indicating hydrophobicity of the active site. However, we observed that AroAT and DY18 had different dependencies although both enzymes have the same residues in the substrate-binding pocket. For substrates with more than 7 carbons, the aminotransferases did not strictly distinguish between substrates with straight and branched side chains. These results suggest that the recognition of manifold hydrophobic substrates of different shapes might require not only the hydrophobicity of the active site but also enzyme flexibility.

Decoloration of yttrium orthovanadate laser host crystals by annealing.

Decoloration of a Czochralski-grown YVO(4) laser host is studied by evaluation of the optical absorption and the photoluminescence spectrum before and after annealing under various atmospheres. Decoloration of yellow asgrown crystals, as a result of the decrease in the absorption near the absorption edge, occurs independently of the air, N(2), and O(2) annealing atmospheres. The most dramatic decrease in the absorption is seen in N(2). Annealing in N(2) atmosphere is suggested to be effective for obtaining the highly transparent crystals.

[Case of lipohyperplasia of the ileocecal valve with adenocarcinoma of the ascending colon].

A rare case of lipohyperplasia of the ileocecal valve contiguous with adenocarcinoma of the ascending colon is reported. The patient was a 67-year-old female with a chief complaint of muco-bloody stool. Barium enema X-ray study revealed a filling defect in the proximal portion of the ascending colon, suggestive of Borrmann II-type carcinoma and enlargement of the ileocecal valve. Ileocecotomy and right colectomy were performed. Histological examination disclosed that the tumor of the ascending colon consisted of well differentiated adenocarcinoma; the proliferation of fat tissue in the submucosa of the ileocecal valve was diagnosed as lipohyperplasia of the ileocecal valve. The histogenesis of this lipohyperplasia seems to be secondary development induced by the adenocarcinoma of the ascending colon.

The novel substrate recognition mechanism utilized by aspartate aminotransferase of the extreme thermophile Thermus thermophilus HB8.

Aspartate aminotransferase (AspAT) is a unique enzyme that can react with two types of substrate with quite different properties, acidic substrates, such as aspartate and glutamate, and neutral substrates, although the catalytic group Lys-258 acts on both types of substrate. The dynamic properties of the substrate-binding site are indispensable to the interaction with hydrophobic substrates (Kawaguchi, S., Nobe, Y., Yasuoka, J., Wakamiya, T., Kusumoto, S., and Kuramitsu, S. (1997) J. Biochem. (Tokyo) 122, 55-63). AspATs from various organisms are classified into two subgroups, Ia and Ib. The former includes AspATs from Escherichia coli and higher eukaryotes, whereas the latter includes those from Thermus thermophilus and many prokaryotes. The AspATs belonging to subgroup Ia each have an Arg-292 residue, which interacts with the distal carboxyl groups of dicarboxylic (acidic) substrates, but the functionally similar residue of subgroup Ib AspATs has not been identified. In view of the x-ray crystallographic structure of T. thermophilus AspAT, we expected Lys-109 to be this residue in the subgroup Ib AspATs and constructed K109V and K109S mutants. Replacing Lys-109 with Val or Ser resulted in loss of activity toward acidic substrates but increased that toward the neutral substrate, alanine, considerably. These results indicate that Lys-109 is a major determinant of the acidic substrate specificity of subgroup Ib AspATs. Kinetic analysis of the interactions with neutral substrates indicated that T. thermophilus AspAT is subject to less steric hindrance and its substrate-binding pocket has a more flexible conformation than E. coli AspAT. A flexible active site in the rigid T. thermophilus AspAT molecule may explain its high activity even at room temperature.

Down-regulation in multiple human cancers of a novel gene, DMHC, from 17q25.1 that encodes an integral membrane protein.

Frequent observations of allelic loss in chromosomal band 17q25.1 in a variety of human cancers have suggested that one or more tumor suppressor genes are present in that region. Moreover, a genetic locus for hereditary focal non-epidermolytic palmoplantar keratoderma, a condition associated with cancer of the esophagus (TOC; Tylosis with Oesophageal Cancer), lies in the same region. We screened cell lines derived from a variety of human cancers by reverse transcription-polymerase chain reaction (RT-PCR) to detect alterations in expression of genes within the region in question, by examining expressed sequence tags located there. These experiments identified an 1834-bp full-length cDNA encoding a novel, 441-amino acid integral membrane protein with seven putative transmembrane domains. This gene showed loss or extreme decrease of expression in 6 of 10 uterine cancer-cell lines, 2 of 11 hepatic cell carcinoma-cell lines, 2 of 7 lung cancer-cell lines, 1 of 6 gastric cancer-cell lines, and 1 of 10 breast cancer-cell lines. (We named it DMHC ("down-regulated in multiple human cancers").) Our results suggest that loss of expression of DMHC at 17q25.1 may play an important role in development of variety of human cancers.

Tubular adenoma with focal squamous metaplasia of the ascending colon.

A case of tubular adenoma with focal squamous metaplasia of the ascending colon in a 66-year-old male is reported. The tumor was a pedunculated polyp with a size of 1.5 X 1.4 X 0.9 cm. Histologically, the tumor showed tubular adenoma with moderate to severe atypia, was accompanied by focal squamous metaplasia. It is thought that squamous epithelial polyp may be derived from colonic adenoma with squamous metaplasia, and that the malignant change of colonic adenoma with squamous metaplasia may lead to squamous cell carcinoma, adenosquamous carcinoma, and mucoepidermoid carcinoma. Only seven cases of colonic adenoma with squamous metaplasia have been reported previously in the literature, and it is yet necessary to discuss the histogenesis, significance, and natural history of colonic adenoma with squamous metaplasia.

Co-segregation of elevated LDL with a novel mutation (D92K) of the LDL receptor in a kindred with multiple lipoprotein abnormalities.

Factors predisposing to the phenotypic features of familial combined hyperlipidemia have not been clearly defined. In the course of investigating familial coronary artery disease in Utah, we identified a three-generation family in which multiple members were affected with type IIa hyperlipoproteinemia (HLP IIa), type IIb hyperlipoproteinemia (HLP IIb), or type IV hyperlipoproteinemia (HLP IV). Because several family members had relatively severe low-density lipoprotein (LDL) cholesterol elevation, in order to dissect the possible contribution to the plasma lipoprotein abnormalities in this pedigree, we identified a novel point mutation in the low-density lipoprotein receptor (LDLR) gene, a G-to-A transition at nucleotide position 337 in exon 4. This change substituted lysine for glutamic acid at codon 92 (D92K) of the LDL receptor. By means of mutant allele-specific amplification we determined that the mutation co-segregated with elevated cholesterol and LDL cholesterol in the plasma of family members with HLP IIa and HLP IIb, but not with the elevated plasma triglycerides seen in HLP IIb and HLP IV patients. Thus, in families with apparent familial combined hyperlipidemia, a defective LDLR allele and other genetic or environmental factors that elevate plasma triglycerides may account for the multiple lipid phenotypes observed in this kindred.

Familial hypercholesterolemia in Utah kindred with novel 2412-6 Ins G mutations in exon 17 of the LDL receptor gene.

Familial hypercholesterolemia (FH) is a monogenic disorder associated with primary hypercholesterolemia. FH is characterized by autosomal co-dominant inheritance with strikingly elevated LDL-cholesterol, the presence of xanthoma and premature atherosclerosis. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To determine the genetic etiology of the lipoprotein abnormalities, we screened DNA samples from the family for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein receptor (LDLR) gene. Novel point mutations were identified in the proband: a one-base insertion of G to a five-G stretch at nucleotides 2412-6 (codons 783-785), causing a frameshift in exon 17 of the LDL receptor gene. The direct sequencing method was used to examine six members of the family recruited for the diagnosis. This method helped to unequivocally diagnose the five individuals as heterozygous for this particular LDL receptor mutation. This method also helped us to diagnose with FH, or to exclude from carrier status, three children between ages 6 and 11.

Familial hypercholesterolemia in Utah kindred with novel R103W mutations in exon 4 of the LDL receptor gene.

Heterozygous familial hypercholesterolemia (FH) is a serious disorder causing twice normal low-density lipoprotein cholesterol levels early in childhood and very early coronary disease in both men and women. Previously published blood cholesterol criteria greatly under-diagnosed new cases of FH among members of known families with FH and over-diagnosed FH among participants of general population screening. Thus, there is a need for accurate and genetically validated criteria for the early diagnosis of heterozygous FH. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To carry out molecular genetic diagnosis of the disease, we screened DNA samples for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein (LDL) receptor gene. Novel point mutations were identified in the proband: a C-to-T transversion at nucleotide position 369, causing substitution of Tryptophan for Arginine at codon 103 in exon 4 of the LDL receptor gene. The SSCP method was used to examine seven members of the family recruited for the diagnosis. This method helped to unequivocally diagnose only the proband as heterozygous for this particular LDL receptor mutation while excluding the remaining six individuals from carrier status with FH.

A novel LDLR mutation, H190Y, in a Utah kindred with familial hypercholesterolemia.

Heterozygous familial hypercholesterolemia (FH) is a serious disorder causing twice normal low-density lipoprotein (LDL) cholesterol levels early in childhood and very early coronary disease in both men and women. Treatment with multiple medications together with diet can normalize cholesterol levels in many persons with FH and prevent or delay the development of coronary atherosclerosis. Previously published blood cholesterol criteria greatly under-diagnosed new cases of FH among members of known families with FH and over-diagnosed FH among participants of general population screening. Thus, there is a need for accurate and genetically validated criteria for the early diagnosis of heterozygous FH. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To carry out molecular genetic diagnosis of the disease, we screened DNA samples for mutations in all 18 exons and the exon-intron boundaries of the LDL receptor gene (LDLR). Novel point mutations were identified in the proband: a C-to-T transversion at nucleotide position 631, causing substitution of tyrosine for histidine at codon 190 in exon 4 of the LDLR gene. The mutant allele-specific amplification method was used to examine 12 members of the family recruited for the diagnosis. This method helped to unequivocally diagnose 7 individuals as heterozygous for this particular LDLR mutation, while excluding the remaining 5 individuals from carrier status with FH.