Synthesis of ethyl (R)-4-chloro-3-hydroxybutanoate with recombinant Escherichia coli cells expressing (S)-specific secondary alcohol dehydrogenase

The synthesis of ethyl (R)-4-chloro-3-hydroxybutanoate ((R)-ECHB) from ethyl 4-chloroacetoacetate was studied using whole recombinant cells of Escherichia coli expressing a secondary alcohol dehydrogenase of Candida parapsilosis. Using 2-propanol as an energy source to regenerate NADH, the yield of (R)-ECHB reached 36.6 g/l (more than 99% ee, 95.2% conversion yield) without addition of NADH to the reaction mixture.

Expression of cholesteryl ester transfer protein in human atherosclerotic lesions and its implication in reverse cholesterol transport

Reverse cholesterol transport (RCT) is the major protective system against atherosclerosis. In this system, cholesteryl ester transfer protein (CETP) is known to facilitate the transfer of neutral lipids between lipoproteins in plasma. We reported the pathophysiological significance of CETP by clinical studies with genetic CETP deficiency, showing that this protein plays a crucial role in the RCT system. However, information about the expression of this protein in the initial step of RCT, macrophages (Mphi) in the blood vessels, is still very limited. In the present study, we have performed immunohistochemical analyses on the expression of CETP in human atherosclerotic lesions. The immunoreactive mass of CETP was abundantly detected in foam cells in human aortic and coronary atherosclerotic lesions, but not in the normal arterial wall. A double immunostaining showed that the majority of CETP-positive foam cells were derived from Mphi and a minor population appeared to derive from smooth muscle cells. Transient transfection of CETP cDNA into COS-7 cells showed that high density lipoprotein (HDL)-mediated efflux of free cholesterol from the cells expressing CETP was much higher than that from mock-transfected cells, while uptake of HDL-lipids was not affected in cells transfected with CETP cDNA. Efflux of free cholesterol from the Mphi obtained from CETP deficiency was significantly decreased compared with that from normal subjects. These data indicate that CETP is expressed in Mphi in the atherosclerotic lesions and may possess an anti-atherogenic function to remove cholesterol from the cells, suggesting another role of CETP at the initial step of RCT.

Absence of Msh2 protein expression is associated with alteration in the FHIT locus and Fhit protein expression in colorectal carcinoma

Frequent loss of Fhit expression has been reported in human gastrointestinal tract carcinomas; opinions remain divergent regarding Fhit expression in colorectal carcinoma (CRC) cases. Recent studies have suggested that Fhit inactivation can be a consequence of defects in mismatch repair proteins, particularly Msh2. Immunohistochemical analysis of Msh2 and Fhit protein expression in 62 CRC cases was performed. The same CRCs were examined for allelic loss at three loci within or near FHIT and for FHIT mRNA expression by reverse transcription-PCR amplification. Half of the 62 CRC cases were positive for Fhit protein. Fhit protein loss correlated significantly with the progression of carcinoma (P < 0.01) as well as lymph node metastasis (P < 0.05). Loss of Msh2 protein correlated significantly with loss of Fhit protein (P < 0.05) and FHIT locus alteration (P < 0.05). Loss of Fhit protein expression was observed in 50% of sporadic CRCs and was significantly more frequent in more advanced cancers. Interestingly, alteration of the fragile FHIT locus and loss of Fhit protein expression were significantly more frequent in sporadic CRCs lacking Msh2 protein, suggesting that this mismatch repair protein may be important in maintaining the integrity of the common fragile locus within the FHIT gene.

Zosteriform metastatic skin cancer: report of three cases and review of the literature

BACKGROUND

Metastatic skin cancer is a rare complication of internal malignancies. Patients who do develop skin metastases seldom present with a zosteriform distribution.

OBJECTIVE

To elucidate the characteristics of zosteriform metastatic skin cancer, 15 cases from the medical literature and 3 cases seen in our clinic were reviewed clinically and histopathologically.

METHODS

The age and sex of each patient, site of the primary tumor, pathology of primary and metastatic lesions, location of the skin cancer and presence of pain were determined for the 18 cases of zosteriform skin cancer.

RESULTS

The most frequent site of the primary tumor was the breast (4 cases), ovary or lung (3 cases each), prostate, bladder or stomach (2 cases each) and uterus or colon (1 case each). The most common site of the skin metastases was the chest wall (8 cases) and abdominal wall (7 cases). The histology of the primary lesion was compatible with adenocarcinoma (10 cases), transitional cell carcinoma or serous papillary cystadenocarcinoma (2 cases each) and ductal carcinoma (1 case). Eleven cases developed on the nearest covering skin and/or on the same side as the primary tumor. Eleven patients complained of pain. Seven cases were treated as herpes zoster with antiviral agents.

CONCLUSION

Approximately 50% of cases of metastatic skin cancer developed on the nearest skin covering and on the same side as the primary tumor. This evidence may be useful when trying to pinpoint the location of the primary tumor. One third of patients with skin metastases were misdiagnosed and their lesions were treated initially as herpes zoster. When a band-like eruption is seen in patients with internal malignancies, the possibility of metastatic skin lesions should be considered. A skin biopsy is necessary to confirm the diagnosis.

Microvascular angina in a patient with aortic stenosis

A 39-year-old woman had exercise-induced ST segment depression associated with chest pain. Cardiac evaluation revealed moderate aortic stenosis (AS), related to the bicuspid valves, with an aortic mean pressure gradient of 22 mmHg, a calculated aortic valve area of 1.3 cm2 and normal left ventricular (LV) peak systolic and end-diastolic pressures, but no LV hypertrophy, resulting in normal LV wall stress. Although the coronary arteries were angiographically normal, rapid atrial pacing and an intracoronary papaverine injection revealed a significantly decreased coronary flow reserve (CFR), which may have played an important role in the pathogenesis of angina pectoris in this patient. Though the CFR is usually decreased in patients with AS, as well as in microvascular angina, in this particular case, it appeared to have decreased as a consequence of microvascular dysfunction rather than of AS-related mechanisms.

Hepatoma-derived growth factor is associated with reduced sensitivity to irradiation in esophageal cancer

Radiotherapy is a useful component of treatment for esophageal cancer. Identification of the genes that are differentially expressed between radiosensitive and radioresistant cancer cells is important for predicting clinical effectiveness of radiotherapy. We established human esophageal cancer cell lines resistant to X-ray. Using differential display, we obtained one gene that was expressed in radiosensitive cells but was rarely expressed in radioresistant cells, and that gene was identical with hepatoma-derived growth factor (HDGF), an acidic polypeptide with mitogenic activity for fibroblasts. The semiquantitative reverse transcription-PCR assay confirmed that HDGF mRNA expression was reduced in established radioresistant cells, and its reduction was associated with reduced sensitivity to irradiation. Radiotherapy was more effective in clinical cases with high HDGF mRNA expression compared with cases with low expression (P < 0.05). The findings demonstrate that HDGF may play an important role in radiosensitivity, and it could be a novel marker predicting effectiveness of radiotherapy in clinical cases.

Discontinuous elongation of nematic gels by a magnetic field

The effects of a magnetic field on the swelling of a nematic gel immersed in a low molecular weight liquid crystal solvent are examined by using a mean field theory. The nematic-isotropic (paranematic) phase transition temperature of the gel and the solvent is controlled by the external field. As a result of an anisotropic coupling between the gel and solvent, the shape of the gel is discontinuously (or continuously) elongated with increasing the strength of the external field. We examine the condition for a first- and second-order volume phase transition of the gel under a magnetic field.

Increase in the stability of serine acetyltransferase from Escherichia coli against cold inactivation and proteolysis by forming a bienzyme complex

Cysteine synthetase from Escherichia coli is a bienzyme complex composed of serine acetyltransferase (SAT) and O-acetylserine sulfhydrylase-A (OASS). The effects of the complex formation on the stability of SAT against cold inactivation and proteolysis were investigated. SAT was reversibly inactivated on cooling to 0 degrees C. Ultracentrifugal analysis showed that SAT (a hexamer) was dissociated mostly into two trimers on cooling to 0 degrees C in the absence of OASS, while in the presence of OASS one trimer of the SAT subunits formed a complex with one dimer of OASS subunits. In the presence of OASS, not only the cold inactivation rate was reduced but also the reactivation rate was increased. Furthermore, SAT became stable against proteolytic attack by alpha-chymotrypsin and V8 protease by forming the complex with OASS. On the other hand, SAT was degraded by trypsin in the same manner both in the presence and in the absence of OASS. The different tendency in the stability against proteolysis with the different proteases was discussed with respect to the substrate specificity of the proteases and amino acid sequence of the C-terminal region of SAT that interacts with OASS.

Adipocyte-derived plasma protein, adiponectin, suppresses lipid accumulation and class A scavenger receptor expression in human monocyte-derived macrophages

BACKGROUND

Excessive lipid accumulation in macrophages plays an important role in the development of atherosclerosis. Recently, we discovered an adipocyte-specific plasma protein, adiponectin, that is decreased in patients with coronary artery disease. We previously demonstrated that adiponectin acts as a modulator for proinflammatory stimuli and inhibits monocyte adhesion to endothelial cells. The present study investigated the effects of adiponectin on lipid accumulation in human monocyte-derived macrophages.

METHODS AND RESULTS

Human monocytes were differentiated into macrophages by incubation in human type AB serum for 7 days, and the effects of adiponectin were investigated at different time intervals. Treatment with physiological concentrations of adiponectin reduced intracellular cholesteryl ester content, as determined using the enzymatic, fluorometric method. The adiponectin-treated macrophages contained fewer lipid droplets stained by oil red O. Adiponectin suppressed the expression of the class A macrophage scavenger receptor (MSR) at both mRNA and protein levels by Northern and immunoblot analyses, respectively, without affecting the expression of CD36, which was quantified by flow cytometry. Adiponectin reduced the class A MSR promoter activity, as measured by luciferase reporter assay. Adiponectin treatment dose-dependently decreased class A MSR ligand binding and uptake activities. The mRNA level of lipoprotein lipase as a marker of macrophage differentiation was decreased by adiponectin treatment, but that of apolipoprotein E was not altered. Adiponectin was detected around macrophages in the human injured aorta by immunohistochemistry.

CONCLUSIONS

The adipocyte-derived plasma protein adiponectin suppressed macrophage-to-foam cell transformation, suggesting that adiponectin may act as a modulator for macrophage-to-foam cell transformation.

Decreased expression of a member of the Rho GTPase family, Cdc42Hs, in cells from Tangier disease - the small G protein may play a role in cholesterol efflux

Cholesterol efflux (CE) is the initial and important step of reverse cholesterol transport (RCT), a major protective system against atherosclerosis. However, most of the molecular mechanism for CE still remains to be clarified. In the present study, cDNA subtraction revealed that the expression of a member of the Rho GTPase family, Cdc42Hs, was markedly decreased in both passaged fibroblasts and macrophages (M&phi;) from patients with Tangier disease (TD), a rare lipoprotein disorder with reduced CE. This small G protein is known to have many cell biological activities such as rearrangement of actin cytoskeleton and vesicular transport, however the association between this molecule and lipid transport has never been reported. We demonstrate that MDCK cells expressing the dominant negative form of Cdc42Hs had reduced CE, inversely ones expressing the dominant active form had increased CE. From these observations, we would like to raise a novel hypothesis that this type of small G protein may play a role in some steps of CE. To our knowledge, the present study is the first demonstration that the expression of this molecule is altered in cells from human disease.

Characteristics of serine acetyltransferase from Escherichia coli deleting different lengths of amino acid residues from the C-terminus

Some properties of serine acetyltransferases (SATs) from Escherichia coli, deleting 10-25 amino acid residues from the C-terminus (SATdeltaC10-deltaC25) were investigated. The specific activity depended only slightly on the length of the C-terminal region deleted. Although the sensitivity of SATdeltaC10 to inhibition by L-cysteine was similar to that for the wild-type SAT, it became less with further increases in the length of the amino acid residues deleted. SATdeltaC10 was inactivated on cooling to 0 degrees C and dissociated into dimers or trimers in the same manner as the wild-type SAT, but Met-256-le mutant SAT as well as SATdeltaC14, SATdeltaC20, and SATdeltaC25 were stable. Since SATdeltaC10, SATdeltaC14, and SATdeltaC25 did not form a complex with O-acetylserine sulfhydrylase-A (OASS-A) in a way similar to SATdeltaC20, it was indicated that 10 amino acid residues or fewer from the C-terminus of the wild-type SAT are responsible for the complex formation with OASS-A. The C-terminal peptide of the 10 amino acid residues interacted competitively with OASS-A with respect to OAS although its affinity was much lower than that for the wild-type SAT.

Adiponectin, a new member of the family of soluble defense collagens, negatively regulates the growth of myelomonocytic progenitors and the functions of macrophages

We investigated the functions of adiponectin, an adipocyte-specific secretory protein and a new member of the family of soluble defense collagens, in hematopoiesis and immune responses. Adiponectin suppressed colony formation from colony-forming units (CFU)-granulocyte-macrophage, CFU-macrophage, and CFU-granulocyte, whereas it had no effect on that of burst-forming units-erythroid or mixed erythroid-myeloid CFU. In addition, adiponectin inhibited proliferation of 4 of 9 myeloid cell lines but did not suppress proliferation of erythroid or lymphoid cell lines except for one cell line. These results suggest that adiponectin predominantly inhibits proliferation of myelomonocytic lineage cells. At least one mechanism of the growth inhibition is induction of apoptosis because treatment of acute myelomonocytic leukemia lines with adiponectin induced the appearance of subdiploid peaks and oligonucleosomal DNA fragmentation. Aside from inhibiting growth of myelomonocytic progenitors, adiponectin suppressed mature macrophage functions. Treatment of cultured macrophages with adiponectin significantly inhibited their phagocytic activity and their lipopolysaccharide-induced production of tumor necrosis factor alpha. Suppression of phagocytosis by adiponectin is mediated by one of the complement C1q receptors, C1qRp, because this function was completely abrogated by the addition of an anti-C1qRp monoclonal antibody. These observations suggest that adiponectin is an important negative regulator in hematopoiesis and immune systems and raise the possibility that it may be involved in ending inflammatory responses through its inhibitory functions. (Blood. 2000;96:1723-1732)

Effects of bienzyme complex formation of cysteine synthetase from escherichia coli on some properties and kinetics

Some properties and kinetics of the free and bound serine acetyltransferases (SATs) and O-acetylserine sulfhydrylase-As (OASS-As) from Escherichia coli were investigated. In some cases, SATdeltaC20, deleting 20 amino acid residues from the C-terminus of the wild-type SAT (Biosci. Biotechnol. Biochem., 63, 168-179 (1999)) was tested for comparison. The optimum pH and stability against some reagents for the free and bound wild-type SATs were similar except for the resistance to cold inactivation. The kinetics for the wild-type SAT and SATdeltaC20 followed a Ping-Pong Bi Bi mechanism with a mixed-type inhibition by L-cysteine. The kinetics and kinetic constants for the wild-type SAT were not changed by the complex formation with OASS-A. The optimum pH for OASS-A was shifted towards an alkaline pH by the complex formation. Thermal stability and stability against some reagents for the free and bound OASS-As were almost the same. On the other hand, the maximum velocity for OASS-A was lowered and dissociation constants for the substrates and products were increased by forming the complex with the wild-type SAT, although the kinetics for the free and bound enzymes followed the same Ping-Pong Bi Bi mechanism. From comparisons of computed courses of L-cysteine formation from L-serine using SAT (wild-type SAT and SATdeltaC20) and OASS-A with the experimental results and changes in the stability of the wild-type SAT by the complex formation, we discuss the role and significance of a complex formation for the cysteine synthetase.

Identification of a GPI-anchored type HDL-binding protein on human macrophages

To identify the HDL3-binding proteins on human macrophages, we examined the involvement of GPI-anchored protein in the binding of HDL3, and tried to purify HDL3-binding protein. From membrane fractions of macrophages, we obtained 80- and 130-kDa HDL3-binding proteins by ligand blotting. Treatment of macrophages with phosphatidylinositol-specific phospholipase C (PI-PLC) significantly decreased the specific HDL3-binding in a dose-dependent manner. Furthermore, treatment with mannosamine, which blocks GPI-anchor formation, decreased specific HDL3-binding in a dose-dependent manner. PI-PLC treatment released from the cells the proteins with an M(r) of 80 kDa, which could also bind HDL3. PI-PLC as well as mannosamine treatment markedly reduced cholesterol efflux from macrophages in association with the decreased HDL-binding. Using HDL3-affinity chromatography, we purified 80-kDa GPI-anchored type HDL3-binding protein. In summary, we demonstrate the implication of 80-kDa GPI-anchored protein in the binding of HDL3 to human macrophages, which might have some role in reverse cholesterol transport.

Schizosaccharomyces pombe Ste7p is required for both promotion and withholding of the entry to meiosis

The fission yeast ste7 mutant cannot mate and undergo meiosis, but shows no defect in vegetative growth. We cloned and characterized the ste7 gene. The deduced ste7 gene product (Ste7p) was a protein of 569 amino acids with no significant similarity to other proteins. Transcription of ste7 was induced by nutrient starvation via the function of the transcription factor Ste11p. Disruption of the ste7 gene blocked both conjugation and meiosis, showing that Ste7p plays a positive role in these two processes, probably activating the pheromone signal pathway. Unexpectedly, overexpression of ste7(+) promoted conjugation but inhibited meiosis in wild-type cells. The temperature-sensitive pat1-114 mutant underwent ectopic conjugation at the semirestrictive temperature when its genetic background was ste7(+), whereas the same mutant initiated haploid meiosis when its genetic background was ste7Delta. Two-hybrid analysis suggested that Ste7p interacts physically with both Pat1p and Mei2p, which together constitute the major switch to initiate meiosis. Ste7p tagged with green fluorescent protein accumulated in haploid cells under nutrient starvation until they completed conjugation, but this protein disappeared when they were to enter meiosis. These observations suggest that Ste7p may have a function to suppress the onset of meiosis until the conjugation process has been duly completed.

L-myc restriction fragment length polymorphism in Japanese patients with esophageal cancer

L-myc polymorphism is a representative genetic trait related to an individual's susceptibility to several cancers. However, there have been no reports concerning the association between esophageal cancer and L-myc polymorphism. To analyze the distribution of polymorphism in Japanese patients with esophageal cancer, a molecular genotyping method using a polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) was used. Based on an analysis of 65 Japanese patients with esophageal cancer and 107 healthy control subjects, a significant difference was observed in either the distribution of genotypes (P=0.012) or of allele frequencies between the two groups (P=0.004). The relative risk of esophageal cancer for genotypes including the shorter allele was 2.9 compared to the longer allele homozygote. Furthermore, the patients with S-allele had a tendency for poor prognosis among those with three genotypes. A significant difference between the distribution of genotypes and the incidence of lymph node metastasis was found based on the clinicopathological features of the cancers. These results suggest that L-myc polymorphism may be implicated as a genetic trait affecting an individual's susceptibility to esophageal cancer, at least among Japanese patients.

[Hypo- and hyper alphalipoproteinemia and genetic abnormalities in reverse cholesterol transport system]

The risk of atherosclerosis has been known to be inversely correlated with the plasma concentration of high-density lipoprotein (HDL)-cholesterol, and we now know HDL plays a protective role against atherosclerosis. The most important mechanism, by which HDL could exert their anti-atherogenic role, is certainly the removal of excess cholesterol from peripheral cells and its transport to the liver, a process commonly called "reverse cholesterol transport system". In this system, many proteins are involved, i.e., ABC1, LCAT, CETP, HTGL and SR-BI. Abnormalities of these proteins reduce the efficacy of the system, and cause abnormalities of HDL and atherosclerosis. In this paper, we review the recent findings on the molecular mechanism of reverse cholesterol transport system, and then discuss hypo- and hyperalphalipoproteinemia, which are caused by genetic abnormalities of the key players.