Characterization of cholyl-adenylate in rat liver microsomes by liquid chromatography/electrospray ionization-mass spectrometry

The cholyl-adenylate, covalently bound 3alpha, 7alpha, 12alpha-trihydroxy-5beta-cholanoic acid (cholic acid) with adenosine 5'-monophosphate having an acid anhydride linkage, has been characterized by means of liquid chromatography/mass spectrometry in an incubation mixture with a rat liver microsomal fraction. The authentic specimen of cholyl-adenylate was synthesized using the carbodiimide method and the structure was confirmed by MS and nuclear magnetic resonance spectroscopy. After incubation of cholic acid with a hepatic microsomal fraction in the presence of adenosine 5'-triphosphate, bile acids were extracted and purified by solid-phase extraction on a Sep-Pak C18 cartridge and then subjected to a LC/MS analysis, where cholyl-adenylate and a CoA thioester of cholic acid (cholyl-CoA) were monitored with characteristic negative ions of m/z 736 and 577, respectively. Cholyl-adenylate was definitely characterized and preferential biotransformation into the acyl-adenylate prior to formation of cholyl-CoA was noted. The nonenzymatic formation of taurine-conjugated cholic acid by incubation of cholyl-adenylate with taurine in a buffer solution was also demonstrated.

Mutation of the type X collagen gene (COL10A1) causes spondylometaphyseal dysplasia

Spondylometaphyseal dysplasia (SMD) comprises a heterogeneous group of heritable skeletal dysplasias characterized by modifications of the vertebral bodies of the spine and metaphyses of the tubular bones. The genetic etiology of SMD is currently unknown; however, the type X collagen gene (COL10A1) is considered an excellent candidate, for two reasons: first, Schmid metaphyseal chondrodysplasia, a condition known to result from COL10A1 mutations, shows a significant phenotypic overlap with SMD; and, second, transgenic mice carrying deletions in type X collagen show SMD phenotypes. Hence, we examined the entire coding region of COL10A1 by direct sequencing of DNA from five unrelated patients with SMD and found a heterozygous missense mutation (Gly595Glu) cosegregating with the disease phenotype in one SMD family. This initial documented identification of a mutation in SMD expands our knowledge concerning the range of the pathological phenotypes that can be produced by aberrations of type X collagen (type X collagenopathy).

Novel and recurrent COMP (cartilage oligomeric matrix protein) mutations in pseudoachondroplasia and multiple epiphyseal dysplasia

Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED) are common skeletal dysplasias with impaired enchondral ossification and premature degenerative joint disease. The two disorders were in the past considered to be distinct clinical entities; however, recent studies have proven that both diseases can result from mutations of the gene encoding cartilage oligomeric matrix protein (COMP). To characterize further COMP mutations and investigate phenotype-genotype relationships, we screened this gene in 15 patients with PSACH or MED by directly sequencing polymerase chain reaction products from genomic DNA. We identified ten mutations involving conserved residues among the eight calmodulin-like repeats of the gene product: seven were novel missense mutations in exons 9, 10, 11, 13 or 14, and the other three resulted from deletion of one of the five GAC repeats in exon 13. We have found that the GAC repeats in the 7th calmodulin-like repeat in exon 13 represent a hot-spot for mutation, and that mutations in the 7th calmodulin-like repeat produce severe PSACH phenotypes while mutations elsewhere in the gene exhibit mild PSACH or MED phenotypes. These genotype-phenotype correlations may facilitate molecular diagnosis and classification of PSACH and MED, and provide insight into the relationship between structure and function of the COMP gene product.

Substrate specificity of THCA-CoA oxidases from rat liver light mitochondrial fractions on dehydrogenation of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid CoA thioester

The substrate specificity of rat liver peroxisomal 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoyl-CoA (THCA-CoA) oxidases, which catalyze the dehydrogenation of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid (THCA) CoA thioester, having an asymmetric center at C-25, to form (24E)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-enoic acid (delta 24-THCA) CoA thioester, was studied. The stable isotope labeled substrates, [3,7,12-18O3]-(25R)- and (25S)-THCA CoA thioesters were synthesized by an exchange reaction of carbonyl oxygens on a steroid nucleus of 3,7,12-trioxo-5 beta-cholestanoic acid, followed by metal hydride reduction and condensation reaction with CoA. After incubation of a mixture of unlabeled (25R)- and 18O-labeled (25S)-THCA CoA thioester, or vice versa, with hepatic peroxisomal THCA-CoA oxidases, biotransformed delta 24-THCA was determined by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry. The delta 24-THCA was derived only from (25S)-THCA CoA thioester, indicating that the 25S epimer of THCA is a preferential substrate on dehydrogenation by THCA-CoA oxidases.

Separatory determination of diastereomeric ibuprofen glucuronides in human urine by liquid chromatography/electrospray ionization-mass spectrometry

A method for the separatory determination of diastereomeric isomers of glucuronic acid conjugates of ibuprofen having a carboxyl group at the chiral center by liquid chromatography (LC)/electrospray ionization (ESI)-mass spectrometry (MS) has been developed. The authentic specimens of acyl glucuronides of R(-)- and S(+)-ibuprofen were chemically synthesized by the Mitsunobu reaction. In the ESI mode, the glucuronides were characterized by an abundant quasi-molecular ion [M-H]-, and the formation of the negative ion was markedly influenced by a drift voltage. The resolution of diastereomeric isomers was achieved on a Develosil ODS-HG-5 column with 20 mM ammonium acetate (pH 5.0):acetonitrile (5:2, v/v) as a mobile phase where diastereomers were monitored with a corresponding quasi-molecular ion. After oral administration of racemic ibuprofen, a preferential excretion of (S)-ibuprofen glucuronide into the urine was observed.

Body composition and cross-sectional areas of limb lean tissues in Olympic weight lifters

The cross-sectional area (CSAs) of bone and muscle tissues in the forearm, upper arm, lower leg, and thigh and body composition were determined by B-mode ultrasound and underwater weighing methods, respectively for 56 college Olympic weight lifters and 28 age-matched non-athletes to investigate the magnitude of musculoskeletal development in the strength-trained athletes belonging to the weight-classified sports event. The average value of fat-free mass (FFM) for the weight lifters ranked 12.6 kg above the regression line of FFM on stature for untrained subjects. In the weight lifters, however, the percentage of fat mass to body mass was also highly correlated to body mass index. Bone and muscle CSAs in every site were significantly larger in the weight lifter than in the untrained subjects with relative differences of 22 to 58% and 17 to 56%, respectively. Moreover, as a result of regression analysis for the mixed data from weight lifters and untrained subjects, significant correlation was found between bone and muscle CSAs in every site (r = 0.620 to 0.791, P < 0.05). The differences in lean (bone + muscle) CSA were still significant in all sites except for the lower leg even when the difference in body size was statistically controlled. The comparisons between the weight lifters and untrained subjects on the lean CSA ratios of site to site and muscle CSA ratios of flexors to extensors indicated that the weight lifters had achieved a high relative distribution of lean tissues in the arms and a dominant development in elbow and knee extensors. Thus, the present results suggested that participation in weight lifting exercises for a long period could increase bone CSA as well as muscle CSA, and induce in the participants a noticeable enlargement in given sites and muscle groups responsible for performing the Olympic lifts.

A mild form of pseudoachondroplasia: minimal epi-metaphyseal involvement of long bones

A problem in diagnosing pseudoachondroplasia (PSACH) is that the pathognomonic changes of vertebral bodies invariably disappear around the age of 10, and an adult case might subsequently be misdiagnosed as MED, Fairbank type, though the latter is less severe than PSACH. We present a Japanese girl (follow-up, 3-10 years of age) whose epi-metaphyseal involvement of long bones was minimal and whose height was +2 S.D. of standard for PSACH in spite of the typical changes of the vertebral bodies. She might not have been diagnosed only as PSACH but also as MED, Fairbank type, after disappearance of the typical vertebral body changes because of the apparent lack of stubby fingers. Since the overlap of PSACH and MED has recently been discussed from the viewpoint of molecular biology, study of the spectrum of clinical features of PSACH is important.

Mutation in Npps in a mouse model of ossification of the posterior longitudinal ligament of the spine

Ossification of the posterior longitudinal ligament of the spine (OPLL) is a common form of human myelopathy caused by a compression of the spinal cord by ectopic ossification of spinal ligaments. To elucidate the genetic basis for OPLL, we have been studying the ttw (tiptoe walking; previously designated twy) mouse, a naturally occurring mutant which exhibits ossification of the spinal ligaments very similar to human OPLL (refs 3,4). Using a positional candidate-gene approach, we determined the ttw phenotype is caused by a nonsense mutation (glycine 568 to stop) in the Npps gene which encodes nucleotide pyrophosphatase. This enzyme regulates soft-tissue calcification and bone mineralization by producing inorganic pyrophosphate, a major inhibitor of calcification. The accelerated bone formation characteristic of ttw mice is likely to result from dysfunction of NPPS caused by predicted truncation of the gene product, resulting in the loss of more than one-third of the native protein. Our results may lead to novel insights into the mechanism of ectopic ossification and the aetiology of human OPLL.

Pseudoachondroplasia with de novo deletion [del(11)(q21q22.2)]

Pseudoachondroplasia (PSACH) is a relatively common osteochondrodysplasia characterized clinically by short-limbed short stature with normal face, and radiographically by platyspondyly and dysplasias of epiphyses and metaphyses of the tubular bones. Recently, mutation of cartilage oligomeric matrix protein has been identified in PSACH. However, clinical variability and genetic heterogeneity have been reported in PSACH, indicating a possible existence of a second PSACH gene. Here, we report on a patient with a typical severe form of PSACH who had a de novo interstitial deletion in the long arm of chromosome 11 [del(11)(q21q22.2)]. The size of the deletion was estimated at 0.8-7.3 Mb using fluorescent in situ hybridization (FISH). This deletion may contain or disrupt a second PSACH locus.

The gene for mesomelic dysplasia Kantaputra type is mapped to chromosome 2q24-q32

Mesomelic dysplasia Kantaputra type (MDK) (MIM *156232) is a new autosomal dominant skeletal dysplasia characterized by dwarfism, shortening of the forearms/lower-legs, carpal/tarsal synostosis, and dorsolateral foot deviation. We studied a Thai family in which 15 members in 3 generations were affected with MDK. With reference to the breakpoints of a balanced translocation [t(2;8)(q31;p21)] in patients from a previously reported Italian family with a skeletal dysplasia that appears similar to MDK, a linkage analysis was performed in the Thai family using 50 CA-repeat markers mapped to nearby regions (2q22-q34 and 8p24-p21) of the translocation breakpoints. The results clearly ruled out a linkage of MDK to marker loci at the 8p24-p21 region, whereas all nine affected members available for the study shared a haplotype at four loci (D2S2284, D2S326, D2S2188, and D2S2314) spanning about 22.7 cM in the 2q24-q32 region. The computer-assisted two-point linkage analysis revealed maximum logarithm of odds (lod) scores of 4.82, 4.21, 4.82, and 4.21 (theta = 0) at these loci, respectively. These data indicated that the MDK locus is in the vicinity of D2S2284 and D2S2188 loci that are most likely mapped to 2q24-q32.

Comparison of muscle cross-sectional areas between weight lifters and wrestlers

The purpose of this study was to investigate the difference in the magnitude of muscular development between Olympic weight lifters and wrestlers through the measurements of fat-free mass (FFM) and limb muscle cross-sectional area (CSA). Subjects were college Olympic weight lifters (N = 34, age = 20.0 +/- 1.3 years, stature = 1.67 +/- 0.07 m, body mass = 70.1 +/- 10.2 kg, X +/- SD) and wrestlers (N = 33,20.3 +/- 1.2 years, 1.69 +/- 0.06 m, 71.0 +/- 1.8 kg) who had identical range of body mass. Body density and the CSAs of reciprocal muscle groups in the forearm, upper arm, lower leg and thigh were measured by underwater weighing and B-mode ultrasound methods, respectively. No significant difference was found in body density between the weight lifters (1.077 +/- 0.007 g x ml(-3)) and wrestlers (1.076 +/- 0.008 g x ml(-3)). Moreover, FFM and the CSA values of all muscle groups tested were similar in the two groups of weight-classified athletes, with an exception that the wrist flexor CSA was significantly larger in wrestlers than in weight lifters, and the knee extensor and thigh (extensors + flexors) CSAs were larger in weight lifters than in wrestlers. The total muscle CSA of every site was significantly correlated to FFM2/3 in the separate groups; r = 0.714 to 0.815 (p < 0.05) in weight lifters and r = 0.769 to 0.919 (p < 0.05) in wrestlers. While the CSA-to-FFM2/3 ratios of the upper arm and wrist flexor muscles were significantly higher in wrestlers than in weight lifters, those of the thigh and knee extensor muscles were higher in weight lifters than in wrestlers. Thus, the present results suggest that an event-related difference exists in the magnitude of limb muscle CSA between competitive weight lifters and wrestlers of similar FFM.

Enantioselective immunoaffinity extraction for simultaneous determination of optically active bufuralol and its metabolites in human plasma by HPLC

A combined method of immunoaffinity extraction with high-performance liquid chromatography has been developed for the enantioselective determination of bufuralol and its metabolites in human plasma. The antibodies having high affinity toward the asymmetric center at the C-1 position of bufuralol and its 1'-oxidized metabolites and low affinity to their antipodes were elicited by immunization of rabbits with immunogens, (1R)- and (1S)-1'-oxobufuralol O-carboxymethyloxime-bovine serum albumin conjugates, respectively. 0.5 ml Of the immunoaffinity adsorbent (7.6 mg.ml-1 for anti-(1S)-antibody and 28.8 mg.ml-1 for anti-(1R)-antibody) prepared by immobilization of an antibody was capable of retaining up to 1 microgram of (R)- and (S)-bufuralol and up to 500 ng of other metabolites. The adsorbates were recovered quantitatively by elution with methanol-10 mM ammonium acetate buffer (pH 5) (95:5, v/v) without any interfering peaks on the high-performance liquid chromatogram. The proposed method was evaluated to be useful for the simultaneous determination of optically active bufuralol and its metabolite in plasma with acceptable recovery and precision.

Stature and severity in multiple epiphyseal dysplasia

We investigated the stature and radiological findings in 15 patients with multiple epiphyseal dysplasia (MED). They were divided into normal-stature and short-stature groups according to their body height after 4 or 5 years of age. Their stature was not related to the involvement of the spine or epiphyses of long tubular bones except for the distal radius. Proximal phalanges and metacarpi were shorter in the short-stature group than in the normal-stature group, indicating that stature in MED had some relationship to the involvement of the wrist and hand. However, some patients in the normal-stature group showed involvement of distal radial epiphyses, and some patients in the short-stature group did not have stubby fingers. There are thus no clear-cut criteria to differentiate between the severe Fairbank type and the milder Ribbing type of MED.

Synthesis of bile acid 24-acyl glucuronides

The synthesis of acyl glucuronides of common bile acids is described. By means of the Mitsunobu reaction employing diethylazodicarboxylate and triphenylphosphine, bile acids were condensed through the inherent C-24 carboxy group with benzyl 2,3,4-tri-O-benzyl-D-glucopyranuronate, which was prepared from 1-O-methyl-alpha-D-glucose. The separation and purification of the beta-anomers at the anomeric position of the sugar moiety were attained by preparative thin-layer chromatography and/or high-performance liquid chromatography on a column packed with phenyl-bonded silica using H2O-MeOH as a mobile phase. The removal of the benzyl group on the sugar moiety was achieved by catalytic hydrogenation with 10% palladium on carbon to yield the desired acyl glucuronides of bile acids. The structures of these acyl glucuronides were confirmed by proton nuclear magnetic resonance spectral properties.

Separation and characterization of carboxyl-linked glucuronides of bile acids in incubation mixture of rat liver microsomes

The carboxyl-linked 24-glucuronides of common bile acids have been identified by means of liquid chromatography (LC)/atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) in an incubation mixture with a male Wistar rat liver microsomal fraction. The authentic specimens of bile acid 24-glucuronide acetate-methyl esters were synthesized unequivocally using the Mitsunobu reaction, and the APCI-mass spectrometric properties of these glucuronide derivatives were also characterized. After incubation of common unconjugated bile acids with hepatic microsomes, glucuronides were extracted and purified with a Sep-Pak C18 cartridge and lipophilic ion exchange gel, piperidino-hydroxypropyl Sephadex LH-20, and then derivatized into the acetate-methyl esters. Subsequent resolution into alpha- and beta-isomers at the glucuronosyl linkage was attained by LC on Cosmosil 5C8 and Sumichiral OA-2500 columns using 200 mM ammonium acetate (pH 7.0)-methanol (1:4, v/v), where 24-glucuronides were monitored with characteristic positive ions [M + NH4]+. The 24-glucuronides of lithocholic, chenodeoxycholic, deoxycholic, ursodeoxycholic and cholic acid were definitely characterized, in contrast to no formation of corresponding 3-glucuronides.

Body composition and isokinetic strength of professional Sumo wrestlers

The purpose of this study was to investigate the profiles of body composition and force generation capability in professional Sumo wrestlers. The subjects were 23 professional Sumo wrestlers [mean age 22.0 (SEM 1.2) years] including those ranked in the lower- (Jonokuchi, n=10), middle- (Sandanme, n=8) and higher-division (Makuuchi, n=5), 22 weight-classified athletes [5 judo athletes, 5 wrestlers, and 12 weight lifters, mean age 20.7 (SEM 0.7) years], and 21 untrained men [mean age 20.1 (SEM 0.2) years]. In the Sumo wrestlers, body mass ranged between 77.0 and 150.0 kg, body mass index between 25.9 and 44.5 kg x m(-2), relative fat mass (%FM) between 11.9 and 37.0%, and fat-free mass (FFM) between 59.1 and 107.6 kg. The Sumo wrestlers showed significantly higher %FM and smaller elbow and knee extensor cross-sectional areas (CSA) than the weight-classified athletes who weighed from 90.4 kg to 133.2 kg. Moreover, isokinetic forces in the flexion and extension of elbow and knee joints, respectively, at three constant velocities of 1.05, 3.14 and 5.24 rad x s(-1) were significantly lower in the Sumo wrestlers than in the weight-classified athletes and untrained subjects when expressed per unit of body mass. However, the median value of FFM relative to body height in the higher-division Sumo wrestlers was ranked high in the range of magnitude among those reported previously in the literature for heavyweight athletes. Moreover, the results on the comparisons within the Sumo wrestlers showed that not only FFM but also force generation capability, expressed both as an absolute term and as a value relative to both body mass and muscle CSA, might be factors contributing to the performance of Sumo wrestlers.

Characteristics of body composition and muscle strength in college Sumo wrestlers

The purpose of this study was to investigate the characteristics of body composition and force generation capacity in college Sumo wrestlers (N=13, age=19.8+/-0.3 yr, stature= 178.5+/-1.6 cm, body mass = 111.2+/-3.8 kg, X+/-SE) in comparison with untrained males (N=18, 20.3+/-0.2 yr, 170.1+/-1.7 cm, 59.2+/-1.4 kg). The Sumo wrestlers had significantly higher average values in relative fat mass (24.8+/-1.0%) and fat-free mass (83.3+/-2.0 kg), estimated by an underwater weighing method, than the untrained subjects (relative fat mass = 12.9+/-0.1 %, fat-free mass = 51.5+/-1.3 kg). Moreover, the Sumo wrestlers had 1.7 to 1.9 times greater cross-sectional areas (CSAs) of elbow flexors and extensors and knee extensors, determined by a B-mode ultrasound technique, compared to those of the untrained subjects. Force values produced during elbow flexion and extension and knee extensions tasks under isokinetic contraction mode at constant velocities of 1.05, 3.14 and 5.24 rad x s(-1) were significantly higher in the Sumo wrestlers than in the untrained subjects. The force value in all test conditions was significantly correlated to the related-muscle CSA, r=0.611-0.910 (p<0.05). The difference between the two groups in force per unit CSA (F x CSA[-1]) during elbow flexion was not significant at all test velocities. However, the Sumo wrestlers showed significantly lower F x CSA(-1) values in elbow extension at 5.24 rad x s(-1) and in knee extension at all test velocities. Thus, the body composition of the Sumo wrestlers was characterized by a high fat content and a large fat-free mass. Moreover, the Sumo wrestlers had considerably larger muscle CSAs of limbs than the untrained subjects. For the Sumo wrestlers, however, force output of the muscles with a pennate structure were not proportional to their CSAs, particularly in knee extensors.

Structure of the gene encoding human colligin-2 (CBP2)

Colligins are collagen-binding proteins localized to the endoplasmic reticulum that belong to the superfamily of serine protease inhibitors and play a role in collagen biosynthesis. Previously, we cloned the human colligin-2 gene (CBP2) and mapped it to chromosome 11q13.15. To further characterize the CBP2 gene, we have determined its genomic structure and the 5'-flanking sequence. The CBP2 gene spanned approximately 11 kb of genomic DNA and consisted of five exons. The promoter sequence of the human gene showed significant homology to that of its murine counterpart, which contained several regulatory sequences including heat-shock and retinoic acid-responsive elements. These findings suggest colligin may function as a collagen-specific molecular chaperon and play a role in the process of retinoic acid-induced differentiation.

Force-velocity relationships and fatiguability of strength and endurance-trained subjects

The isokinetic forces, produced by a single as well as repetitive maximal knee extensions, and cross-sectional area (CSA) of the quadriceps femoris muscles were measured in 36 young adult males aged from 18 to 24 years: strength-trained (weight resistance-trained subjects, WT, N = 8), endurance-trained (middle distance runners, RUN, N = 13), and age-matched untrained subjects (UNT, N = 15). The CSA was measured using a B-mode ultrasound technique at the midpoint of the thigh length. The isokinetic forces at three velocities (1.05, 3.14 and 5.24 rad.s-1) were significantly correlated to CSA in all subjects (r = 0.01-0.849, p < 0.05). The absolute values in force development at three test velocities were significantly higher in WT than in RUN and UNT. While average values of force output per unit CSA were almost the same among the subject groups at test velocities of 3.14 and 5.24 rad.s-1, it was significantly higher in WT than in UNT at 1.05 rad.s-1. The repetitive maximal task consisted of 50 consecutive maximal knee extensions with constant velocity of 3.14 rad.s-1. The mean value of force (MF) of every 5 consecutive and all trials, respectively, was significantly correlated to CSA in all subjects (r = 0.448-0.885, p < 0.05). The average percentage of decline of MF with 50 maximal contractions was significantly lower in RUN (36 +/- 5%, mean +/- SE) than in WT (59 +/- 2%) and UNT (47 +/- 3%), and in UNT than in WT. The average values of MF per unit CSA for RUN became significantly higher than those for WT and UNT on and after the 36th-40th trial. Thus, force output during a single as well as repetitive maximal contractions was significantly correlated to muscle CSA. In terms of force per unit muscle CSA, however, WT and RUN showed specific force-velocity relation and fatiguability during repetitive maximal contractions, respectively, which could be considered as a result of muscle adaptation to their own training regimens.

Separation and detection of bile acid 3-glucuronides in human urine by liquid chromatography/electrospray ionization-mass spectrometry

A method for the separation and detection of bile acid 3-glucuronides by liquid chromatography (LC)/electrospray ionization (ESI)-mass spectrometry (MS) has been developed. On the ESI mode, glucuronides were characterized by an intense pseudo-molecular ion [M-h]- with a doubly charged ion [M-2H]2-, and the ratio of these negative ions were markedly influenced by an acidic component of salt added to a mobile phase, according to a pKa value of an acidic moiety at C-24. Bile acid 3-glucuronides in human urine were extracted with a SepPak C18 cartridge, followed by purification on lipophylic ion exchange gel, piperidinohydroxypropyl Sephadex LH-20. Subsequent resolution into unconjugated, glycine and taurine conjugated bile acid 3-glucuronides was attained by LC on a Develosil ODS-HG-5 column using 20 mM ammonium acetate (pH 7.0)-methanol (10:12, v/v) as a mobile phase, where 3-glucuronides were monitored with a characteristic negative ion [M-H]-. The newly developed method was applied to the quantitatiation of bile acid 3-glucuronides in human urine with satisfactory sensitivity and reliability.

Structure and chromosomal assignment of the human S1-5 gene (FBNL) that is highly homologous to fibrillin

The human S1-5 gene (fibrillin-like; FBNL) was originally isolated from a subtractively enriched cDNA library established from a subject with Werner syndrome (WS). We isolated genomic clones containing the entire S1-5 gene and determined its genomic structure including the exon-intron organization. The gene spanned approximately 18 kb of genomic DNA and consisted of 12 exons. Its expression was abundant in all tissues examined except brain and peripheral leukocytes, where it was undetectable. In addition, we have mapped S1-5 by fluorescence in situ hybridization to chromosome 2p16, a position that excludes it as a candidate for WS. Our data should facilitate an understanding of the function and regulation of S1-5 in human tissues.

Force generation capacity of knee extensor muscles in speed skaters

The force generation capacities during a single as well as repetitive maximal knee extensions were investigated in speed skaters in relation to the cross-sectional area (CSA) of quadriceps femoris muscles. The subjects were 15 male and 12 female speed skaters, and an age-matched untrained group (20 men and 21 women). An isokinetic dynamometer was used to determine force output at three constant velocities of 1.05, 3.14 and 5.24 rad.s-1 and to perform 50 repetitive maximal contractions at 3.14 rad.s-1. The CSA was measured by using a B-mode ultrasound technique at the midpoint of the thigh length. The isokinetic force produced at each test velocity was significantly correlated to CSA in all the subjects (r = 0.867-0.920, P < 0.05). There was no significant difference in force (F) per unit CSA (F.CSA-1) at the three test velocities between the speed skaters and untrained subjects within the same sex. In both the speed skaters and untrained subjects, the women showed significantly lower F.CSA-1 at 3.14 and 5.24 rad.s-1 than the men. The means of force output (F) of every five consecutive and all trials during the repetitive maximal bout were significantly correlated to CSA in all the subjects (r = 0.889-0.934, P < 0.05). Compared to the untrained subjects, the speed skaters showed significantly higher F for every five consecutive contractions even when calculated per unit of CSA (F.CSA-1), and had lower percentage of decline of F during a trial span between the 6th-10th and 41st-45th trials. For the untrained subjects, F.CSA-1 for every five consecutive contractions was significantly lower in the women than in the men. For the speed skaters, the men showed significantly higher F.CSA-1 than the women during a trial span from the 1st-5th trial to the 31st-35th trial, although there was no significant sex difference in the ratio on and after the 36th-40th trial. From these results, it is concluded that the speed skaters show a higher muscle performance in a repetitive maximal contraction task rather than in a single contraction compared to the untrained subjects. In addition, judging from the results for the speed skaters, the women might be less trainable than the men in the F.CSA-1 during a single contraction at a fast velocity as well as repetitive maximal contractions.

A novel enzyme system for the reduction of 3-oxo bile acids in human red blood cells

7 alpha,12 alpha-Dihydroxy-3-oxo- and 3,7,12-trioxo-5 beta-cholanoic acids labeled with 18O atoms were incubated with human red blood cells, and the biotransformation products were separated and characterized by gas chromatography-mass spectrometry as the pentafluorobenzyl ester-trimethylsilyl and -dimethylethylsilyl ether derivatives with the negative ion chemical ionization mode. The reduced products, 3 beta,7 alpha,12 alpha-trihydroxy-5 beta-cholanoic acid for the former, and 3 alpha-hydroxylated dioxo bile acid together with 3 beta-hydroxylated 7,12-dioxo-5 beta-cholanoic acid for the latter, were identified as metabolites. When 3-oxo bile acid was incubated with human blood denatured at 70 degrees C for 2 min, no metabolites were formed. The enzymic reduction activity has been localized in the red blood cell fraction.

Sex difference in force generation capacity during repeated maximal knee extensions

The force generation capacity, during 50 repeated maximal knee extensions with a constant velocity of 3.14 rad.s-1, and cross-sectional area (CSA) of the quadriceps femoris muscles were determined for untrained women (n = 36) and men (n = 27) aged from 18 to 25 years. As force scores in the maximal repetitions, the mean values of force (F) of every 5 consecutive and all trials and the percentage of decline of F (%D) with 50 contractions were calculated. The CSA was measured by using a B-mode ultrasound technique at the midpoint of the thigh length. The F decreased from 303 (SEM 13) N at the 1st-5th trial to 155 (SEM 9) N at the 46th-50th trial for the men, and from 202 (SEM 9) N to 94 (SEM 4) N for the women. The F of every 5 consecutive and all trials were significantly correlated to muscle CSA: for the men r = 0.552-0.872 (P < 0.01) and for the women r = 0.609-0.857 (P < 0.01). The men showed significantly higher F at every 5 consecutive trials than the women even when calculated per unit muscle CSA (F.CSA-1). There were significant correlations between %D and F.CSA-1 at the 1st-5th trial: r = 0.538 (P < 0.01) for the men and r = 0.631 (P < 0.01) for the women, respectively. The average values of %D were almost the same in both sexes: for the men 48 (SEM 3) % and for the women 52 (SEM 2) %, respectively. However, an ANCOVA calculation on %D, using F.CSA-1 at the 1st-5th trial as the covariate, indicated that the women had significantly higher %D than the men. Thus, the force output during the maximal repetitions was significantly correlated to the CSA of quadriceps femoris in both sexes. The force output was lower in the women than in the men even when the difference in the muscle CSA was allowed for. The women had higher %D than the men when force output per unit muscle CSA during the initial 5 repetitions was compared.