[Obstruction of the true lumen by retrograde perfusion during repair of DeBakey type I aortic dissection: a case report]

Retrograde femoral perfusion is often used during the repair of DeBakey type I aortic dissections, however, it may cause serious ischemic damage of vital organs even though the arterial cannula is properly placed. A 58-year-old woman with chest pain was admitted to our hospital. She was operated on urgently because chest computed tomograms revealed that she suffered from a DeBakey type I aortic dissection. A ringed graft, 22 mm in diameter, was implanted into the ascending aorta using retrograde perfusion through the right femoral artery. Following the removal of the aortic cross-clamp and rewarming, the prosthetic graft remained flaccid and the heart failed to resume beating. We speculated that retrograde femoral perfusion caused the true lumen obstruction while distending the false lumen. This resulted in blocking reperfusion of the coronary arteries. After antegrade perfusion was initiated through an 8 mm Dacron graft which was anastmosed to the ringed graft, the heart soon resumed beating. During the repair of DeBakey type I aortic dissections, this serious complication should be anticipated. If it occurs, retrograde femoral perfusion must be exchanged for antegrade aortic perfusion before irreversible changes occur.

[Tricuspid valve replacement by right thoracotomy with minimal dissection in reoperations]

We report two cases of tricuspid valve replacement for tricuspid valve insufficiency as reoperations following mitral valve replacement through midline sternotomy. A right thoracotomy was used to approach the tricuspid valve. To avoid the risk of cardiac laceration, cardiopulmonary bypass was instituted after cannulation of the femoral artery and of superior vena cava through right atrium with balloon caval occlusion and inferior vena cava through the femoral vein with balloon caval occlusion. Without aortic cross clamping under mild hypothermia, right atriotomy was performed through adherent parietal pleura, pericardium, and right atrial wall without dissection. Tricuspid valve was replaced utilizing the bioprosthetic valve with good clinical results. These new measures were expeditiously carried out without dissection of the heart, which has been deemed to be the risk of reoperations.

Three different point mutations in the butyrylcholinesterase gene of three Japanese subjects with a silent phenotype: possible Japanese type alleles

OBJECTIVE

To investigate genetic mutations in three Japanese subjects homozygous for silent butyrylcholinesterase mutations.

METHODS AND RESULTS

One of them was compound heterozygous for two mutations; GGA(Gly) to CGA(Arg) at codon 365 (G365R) and CAA(Gln) to TAA(Ter) at codon 119 (Q119X). The other two subjects were homozygous for different missense mutations: CGT(Arg) to TGT(Cys) at codon 515 (R515C) and G365R, respectively. Simple identification methods for all of the mutations were developed and applied for family analysis and to control individuals. Two mutations, G365R and R515C, have been reported in the Japanese population, while the nonsense mutation Q119X was discovered in the present study. Genetic heterogeneity between human populations with regard to the butyrylcholinesterase gene was suggested.

CONCLUSIONS

Among the three mutations found in this investigation, one was novel, and none of these mutations have been reported outside Japan.

[A family of hereditary motor and sensory neuropathy type I with a mutation (Arg98-->His) in myelin Po--report on a second Japanese family]

A 46-year-old housewife had complaints of insidiously progressive muscle weakness and paresthesia in the distal lower limbs. On neurological examination, a slight to moderate degree of muscle weakness with slight atrophy was observed in the bilateral intrinsic hand muscles. A severe degree of muscle weakness with moderate atrophy was observed in tibialis anterior, gastrocnemius and soleus muscles. Muscle stretch reflexes were decreased in the upper limbs and absent in the lower limbs, without pathologic reflexes. She had a steppage gait. Vibratory sensation was slightly decreased in the hands and moderately decreased in the feet. Touch, pain and temperature sensations were also moderately decreased only in the feet. On laboratory examination, glycosuria (5.6g/dl) was noted. Fasting blood sugar was 226mg/dl with an elevated hemoglobin A1C level (12.7%). The right median motor and sensory nerve conduction velocities were 14.8 and 20.3 m/sec, respectively, with a markedly prolonged distal latency. No muscle action potential was obtained from stimulation of the right tibial nerve. Also, no nerve action potential was elicited from stimulation of the right sural nerve. A fascicular biopsy of the right sural nerve revealed the presence of both demyelinated and remyelinated axons, and an onion-bulb formation with a marked decrease in the density of the myelinated fibers. Based on the neurological examination and nerve conduction studies of the family members, a younger sister, younger brother and an elder daughter of the proband were found to be affected by demyelinating polyneuropathy. Diabetes mellitus was not found among the family members with laboratory evidences of demyelinating polyneuropathy. Based on the family history, an uncle on the mother's side of the proband, the proband's grandmother and a younger daughter of a proband's brother were considered to be affected. The uncle and grandmother had diabetes mellitus. Therefore, we concluded that this family had HMSN type I with autosomal dominant inheritance. In the studies on fluorescence in situ hybridization, and restriction fragment length polymorphism of the genomic DNA of the proband, a DNA duplication in the 17p11.2-12 region was not observed. However, the direct sequencing analysis of DNA fragments from genomic DNA encoding the Po gene of the proband revealed a substitution of histidine for arginine at the codon 98 in the extramembranous domain of Po. She was heterozygous for the mutant allele and normal allele. Alterations in the tertiary structure of the extramembranous domain of Po may result in an impairment of the peripheral myelin compaction. This is the second Japanese family with the same mutation (Arg98-->His) of myelin Po as reported previously by us, and this type of case is rare in the literature. Therefore, the mutation at the codon 98 may play a critical role in the development of the myelin abnormality in HMSN type IB.

Simple and selective assay of 4-hydroxymephenytoin in human urine using solid-phase extraction and high-performance liquid chromatography with electrochemical detection and its preliminary application to phenotyping test

A simple and selective HPLC method for the determination of 4-hydroxymephenytoin (4-OH-M) in human urine, using a controlled potential coulometric detector equipped with a dual working electrode cell of fully porous graphite, has been developed. After acid hydrolysis of urine, 4-OH-M and the internal standard (I.S.), 5-hydroxy-1-tetralone, were extracted from urine by means of a Bond Elut Certify LRC column. The extracts were chromatographed on a reversed-phase mu Bondapak C18 column using methanol-50 mM KH2PO4 (pH 4.0) (30:70, v/v) as the mobile phase at a flow-rate of 1.0 ml/min. Electrochemical detection at applied potential of 800 mV resulted in a limit of quantitation of 0.76 micrograms/ml. The method showed a satisfactory sensitivity, precision, accuracy, recovery and selectivity. The present method was applied to the phenotyping test in thirteen Japanese healthy volunteers who received an oral 100-mg racemic mephenytoin. The phenotypes determined by the present method were found to be in agreement with those obtained with the reported customary assay based on gas chromatography.

[Clinicopathological study of interstitial foam cells in idiopathic membranous nephropathy. Consideration of the appearance of interstitial foam cells in renal tissue]

We conducted an immunohistological investigation on the pathogenesis of interstitial foam cell formation in patients with idiopathic membranous nephropathy (MN). The patients were divided into two groups: Group I consisted of 23 MN patients with interstitial foam cells; Group II consisted of the other 159 patients without foam cells. Age at renal biopsy, duration of proteinuria, blood pressure and other clinical parameters were not significantly different between the two groups. The proportion of nephrotic patients in Group I was 52.2% (12/23), and was not significantly different from that in Group II (48.4%, 77/159). Renal biopsy specimens were examined by immunoperoxidase studies using monoclonal antibodies. The interstitial foam cells were positive for EBM11 (CD68) and 25F9, which are markers of macrophage (M phi) and mature M phi, respectively, but did not express markers of T cells. In interstitial infiltrating cells, both M phi and T cells were observed, but mature M phi were seldom seen. Furthermore, LFA-1 and ICAM-1, but not ICAM-3 (the third ligand for LFA-1) were observed in the interstitial foam cells. LFA-1 and ICAM-3 were observed mainly in interstitial infiltrating cells, but ICAM-1 was observed to a much lesser extent in these cells. These results suggest that interstitial foam cells in MN may be independent of severe hyperlipidemia and proteinuria, and that there may be different mechanisms underlying the accumulation of interstitial foam cells and infiltrating m phi s. Further investigations are required to clarify the pathogenesis of interstitial foam cells in renal tissue.

Colorimetric assay system for screening antiviral compounds against hepatitis B virus

A highly sensitive, rapid, and accurate assay system was developed for the in vitro evaluation of anti-hepatitis B virus (anti-HBV) agents. Chronic HBV-producing HB611 cells were used in combination with immunoaffinity purification, polymerase chain reaction (PCR), and hybrid capture detection. HB611 cells were incubated with putative anti-HBV agents for 7 days in 96-well microtiter plates. HBV was purified from HB611 cell culture media using immunoaffinity purification. The HBV DNA was extracted, amplified with PCR, and assayed using a hybrid capture colorimetric method. This assay provided quantitative detection of extracellular HBV DNA from 25 microliters of cell culture media. Using the colorimetric method, we found that 50% effective concentration levels of several known anti-HBV agents (HPMPA, PMEDAP, PMEA and others) were similar to those reported in studies using Southern blot analysis. These results demonstrate that this new and easily automated colorimetric assay system can be used for the rapid and accurate assessment of anti-HBV compound selectivity.

Two families of murine carbohydrate ligands for E-selectin

In search of endogenous oligosaccharide ligands for the endothelial adhesion molecule E-selectin in mouse, glycolipids from tissues and the neutrophilic cell line 32D c13 were tested for E-selectin binding. Kidneys of BALB/c and NMRI mice (but not CBA) and the 32D c13 cells were found to contain minor glycolipid populations that support strongly the binding of murine E-selectin. By chromatogram binding experiments and in situ liquid secondary ion mass spectrometry (LSIMS) with neoglycolipids derived from their endoglycoceramidase-released oligosaccharides, in conjunction with compositional and linkage analyses, one of the glycolipid ligands in kidney was identified as the Le(x)-active extended globo-glycolipid: [formula: see text] Neoglycolipids enriched for the ligand structures were obtained from oligosaccharides released by endo-beta-galactosidase from the 32D c13 cells. By TLC-LSIMS and antibody binding, the main E-selectin binding determinant on these was identified as sialyl-Le(a).

Identification of the sequence on NS4A required for enhanced cleavage of the NS5A/5B site by hepatitis C virus NS3 protease

In addition to NS3 protease, the NS4A protein is required for efficient cleavage of the nonstructural protein region of the hepatitis C virus polyprotein. To investigate the function and the sequence of NS4A required for the enhancement of NS3 protease activity, we developed an in vitro NS3 protease assay system consisting of three purified viral elements: (i) a recombinant NS3 protease which was expressed in Escherichia coli as a maltose-binding protein-NS3 fusion protein (MBP-NS3), (ii) synthetic NS4A fragments, and (iii) a synthetic peptide substrate which mimics the NS5A/5B junction. We showed that the NS3 protease activity of MBP-NS3 was enhanced in a dose-dependent manner by 4A18-40, which is a peptide composed of amino acid residues 18 to 40 of NS4A. The optimal activity was observed at a 10-fold molar excess of 4A18-40 over MBP-NS3. The coefficient for proteolytic efficiency, kcat/Km, of NS3 protease was increased by about 40 times by the addition of a 10-fold molar excess of 4A18-40. Using a series of truncations of 4A18-40, we estimated that amino acid residues 22 to 31 in NS4A (SVVIVGRIIL) constituted the core sequence for the effector activity. Single-substitution experiments with 4A21-34, a peptide composed of amino acid residues 21 to 34 of NS4A, suggested the importance of several residues (Val-23, Ile-25, Gly-27, Arg-28, Ile-29, and Leu-31) for its activity. In addition, we found that some single-amino-acid substitutions in 4A21-34 were able to inhibit the enhancement of NS3 protease activity by 4A18-40. This approach has potential as a novel strategy for inhibiting the NS3 protease activity important for hepatitis C virus proliferation.

Isolation and mapping of a human gene (RABL) encoding a small GTP-binding protein homologous to the Ras-related RAB gene

Many subgroups of the RAB gene, a member of the RAS superfamily have been identified. Here we report the isolation and analysis of a cDNA encoding a putative small GTP-binding protein, designated RABL, from a human fetal lung cDNA library. RABL encodes 216 amino acids that are 86% identical to members of the RAB5 subfamily and it shows 94% homology in nucleotide sequence with RAB5C of dog. This gene was expressed ubiquitously in all human tissues examined. By fluorescence in situ hybridization we mapped RABL to chromosome band 17q21.2.

Isolation and mapping of a human gene (RPD3L1) that is homologous to RPD3, a transcription factor in Saccharomyces cerevisiae

We have isolated a novel human gene RPD3L1, that is highly homologous to a transcription factor in Saccharomyces cerevisiae, RPD3 (reduced potassium dependency 3), from a human fetal lung cDNA library. The cDNA clone, hRPD3, consists of 2,100 nucleotides that contain an open reading frame of 1446 nucleotides encoding 482 amino acids. It shares 62% identity in nucleotide sequence and 52% identity in amino acid sequence to RPD3. This gene is expressed at various levels in all tissues examined. Furthermore, we were able to map it to chromosome band 1p34.1 by FISH.

Long-term effects of intensive therapy combined with tonsillectomy in patients with IgA nephropathy

IgA nephropathy (IgAN) is the most common form of glomerular disease in the world. However, there is currently no established therapy for IgAN. To assess treatment regimens for IgAN, we investigated a retrospective long-term follow-up study comparing an intensive therapy with a conventional therapy. Clinical outcomes 5 years after the initiation of treatment in two centers were compared. In one center, patients were treated with tonsillectomy combined with steroid pulse, cyclophosphamide, anti-platelet drugs and warfarin (intensive therapy group, Group A, n = 50). In the other center patients were treated with anti-platelet drugs, warfarin or no treatment (conventional therapy group, Group B, n = 50). At the beginning of treatment, the two groups were well matched in terms of age, sex, blood pressure, urinalysis, and creatinine clearance. Five years after the initiation of treatment, proteinuria was remarkably reduced from 1.6 g/day to 0.5 g/day in Group A, whereas no significant change in proteinuria was observed in Group B. Creatinine clearance significantly improved from 77.6 ml/mm to 89.4 ml/min in Group A, whereas creatinine clearance deteriorated from 70.9 ml/min to 62.5 ml/min during 5 years in Group B. Our results indicate that early intensive therapy for IgAN is potentially of great value, and warrants close investigation.

[Enzyme kinetics for enzyme immunoassay]

The rate of reaction involving an enzyme is greatly influenced by temperature, pH, concentration of the substrate, and a number of other factors. Therefore, an accurate measurement of enzyme-catalyzed reaction is important for enzyme immunoassay. The substrate concentration needed for half-maximum velocity (1/2 Vmax) is called the Km value (Michaelis constant) and is expressed in units of substrate concentration (moles per liter or M). Km may be considered an approximate measure of affinity of an enzyme for its substrate: the lower the Km, the higher is the affinity. At times, optimum conditions cannot be used, and compromises in optimum assay conditions must be made.

Substitution of lysine for arginine in the N-terminal 217th amino acid residue of the H gamma II of Staphylococcal gamma-hemolysin lowers the activity of the toxin

The staphylococcal toxin gamma-hemolysin consists of two protein components, LukF and H gamma II. Staphylococcus aureus P83 was found to have five components, LukF, LukF-PV, LukM, LukS, and H gamma II for leukocidin or gamma-hemolysin. H gamma II of S. aureus P83 was demonstrated to be a naturally-occurring analogous molecule of H gamma II [H gamma II(P83)], in which the 217th arginine residue was replaced by lysine. The H gamma II(P83) showed about 50% of the hemolytic activity of normal H gamma II in the presence of LukF.

In vitro metabolism of nefiracetam by liver microsomes from rats, dogs and monkeys

The in vitro metabolism of nefiracetam (CAS 77191-36-7, N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide, NEF, DM-9384), a novel cognition enhancer, has been investigated using liver microsomes from rats, dogs and monkeys. Microsomal metabolism of NEF showed qualitatively a similar profile in three species tested. Six metabolites were generated from incubation of NEF with liver microsomes. Their structures were identified using a thermospray LC/MS/MS (liquid chromatography/tandem mass spectrometry) method, as regioisomers of monhydroxylated derivatives of NEF: the 3-hydroxy (3-OH-NEF); 4-hydroxy (4-OH-NEF); 5-hydroxy (5-OH-NEF); 3'-hydroxy (3'-OH-NEF); 4'-hydroxy (4'-OH-NEF); hydroxymethyl (HM-NEF) metabolites. The heat lability, NADPH requirement and inhibition by prototype cytochrome P450 inhibitors (proadifen and metyrapone) implies that NEF oxidations are catalyzed by cytochromes P450. The major metabolic route was 5-OH-NEF formation in all species, corresponding well with the previous investigations in vivo. Inhibitory effects of alpha-naphthoflavone and quinidine on NEF hydroxylation suggest that several isoforms of cytochromes P450 are involved in the formation of these NEF metabolites.

A screening system for antiviral compounds against herpes simplex virus type 1 using the MTT method with L929 cells

We developed the improved MTT assay system for in vitro evaluation of anti-HSV-1 agents using L929 cells derived from mouse connective tissue. This assay system provides results in 4 days using a 96-well microplate. The EC50 values of several anti-HSV agents (ACV, BVaraU, and others) were found to be similar to those obtained by the plaque reduction method using MRC-5 cells. The present MTT assay is rapid, accurate, and may be useful as an automatic screening system for evaluation of anti-HSV-1 compounds.

Hepatocyte growth factor stimulates liver regeneration and elevates blood protein level in normal and partially hepatectomized rats

The effects of recombinant human hepatocyte growth factor (HGF) on liver growth and function of normal and partially hepatectomized rats have been examined. HGF was continuously administered into the jugular vein because it was rapidly eliminated from the plasma (t1/2 alpha; approximately 4.5 min) and degraded. In normal rats, the labeling index of hepatocytes was increased about 6 times by the administration of HGF. HGF also decreased the prothrombin time and increased the hepaplastin and serum albumin content. In 70%-hepatectomized rats, HGF stimulated liver regeneration and increased the level of blood proteins such as hepaplastin in a dose-dependent manner. The stimulation of serum protein level seemed to result from not only the increase of hepatic cell number but also the direct effect of HGF on the protein production in hepatocytes, because HGF rapidly enhanced the protein synthesis prior to the increase of cell number and increased the mRNA content of albumin in the liver in vivo. In addition, a combination of heparin with HGF further accelerated the effects of HGF described above, possibly due to the decrease of HGF clearance. These findings suggest that HGF accelerates both the hepatic regeneration and function in vivo, and that rhHGF is clinically expected to be a potent therapeutic agent in hepatectomy and liver injury.

[Progress in biotechnology and its clinical application to isozyme diagnosis]

Recent progress in biotechnology is tremendous and its application to isozyme diagnosis has been altered. First, the mechanism of isozyme system in molecular level has been revealed and clinical assessment of isozymes has been followed. Several examples are shown: tumor-producing amylase is caused by translocation of amylase gene; serum cholinesterase is encoded by only one gene; pyruvate kinase gene has two independent exon, containing translation initiator signal; electrophoretic variant of lactate dehydrogenase is caused by missense mutation; alkaline phosphatase isozymes are constituted from different allele products and post-translational modification. Second, improvement of assay procedure by using biotechnology have made isozyme analysis easier, faster, more convenient and more precise. Stable enzymes and monoclonal antibodies against the produced enzymes have been utilized for a different recognition of isozymes. It is believed that a diagnostic system of isozymes will be established in detail.

Isolation of 115 human chromosome 8-specific expressed-sequence tags by exon amplification

Exon-amplification experiments were undertaken to isolate potentially transcribable sequences from cosmid clones that previously had been mapped to subchromosomal bands of human chromosome 8 by fluorescence in situ hybridization. From 253 cosmids subjected to this procedure so far, we isolated 169 fragments and confirmed that they had been derived from the original cosmid clones. Among them, 38 revealed homology to repetitive DNA sequences such as Alu and L1 elements. The other 131 were unique sequences, but of these only 115 contained discernible open reading frames. Among these 115 sequences, 15 were identical to parts of six known genes listed in the public database. On the basis of information derived from mapping the original cosmid clones, we were able to localize two of these known genes, zinc finger protein 7 and heat shock transcription factor 1, to 8q24.3. Furthermore, we have proven that some of these clones are parts of the transcribed products by an exon connection method or by isolation of a novel cDNA that is homologous to murine clathrin-associated protein. The expressed-sequence tags isolated here will be useful resources for a transcriptional map of chromosome 8 and for isolation of new genes.

Genetic basis of the silent phenotype of serum butyrylcholinesterase in three compound heterozygotes

Three Japanese patients showed very low butyrylcholinesterase activity in their sera and appeared to be homozygous for silent genes for butyrylcholinesterase. From DNA analysis, all three patients were compound heterozygotes: GGA(Gly) to CGA(Arg) at codon 365 (G365R) and TTC(Phe) to TCC(Ser) at codon 418 (F418S) in patient 1, G365R and CGT(Arg) to TGT(Cys) at codon 515 (R515C) in patient 2 and ACT(Thr) to CCT(Pro) at codon 250 (T250P) and AGA(Arg) to TGA(Stop) at codon 465 (R465X) in patient 3. The K-variant, GCA(Ala) to ACA(Thr) at codon 539, was also found in patients 1 and 2. Simple identification methods for all the mutations were developed and applied to family analysis and control individuals. The mutant alleles (with silent gene and K-variant) were segregated as predicted by theory in pedigrees of patients 1 and 2. Four of the mutations, F418S, R515C, T250P and R465X, were initially discovered in Japan and genetic heterogeneity among the human population for the butyrylcholinesterase gene was suggested.