Human N-acetylglucosamine-6-O-sulfotransferase involved in the biosynthesis of 6-sulfo sialyl Lewis X: molecular cloning, chromosomal mapping, and expression in various organs and tumor cells

N-Acetylglucosamine-6-O-sulfotransferase catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 6 of a non-reducing N-acetylglucosamine (GlcNAc) residue. We have cloned human GlcNAc-6-O-sulfotransferase cDNA, based on the sequence homology to cloned cDNA of mouse GlcNAc-6-O-sulfotransferase. The predicted protein sequence of the human enzyme was highly homologous to that of the mouse enzyme; in the 363 amino acid stretch of the catalytic region, the two proteins were nearly identical except for conservative changes in 3 amino acid residues. The expressed enzyme transferred sulfate to GlcNAcbeta1-3Galbeta1-4GlcNAcbeta1-3Galbeta1-4Gl cNAc. Co-transfection of the enzyme cDNA and fucosyltransferase VII cDNA into COS-7 cells resulted in cell surface expression of 6-sulfo sialyl Lewis X. Fluorescence in situ hybridization analysis revealed that the GlcNAc-6-O-sulfotransferase gene is located on human chromosome 7q31. mRNA of the human enzyme was strongly expressed in the bone marrow, peripheral blood leukocytes, spleen, brain, spinal cord, ovary, and placenta, and moderate levels of expression were observed in many organs including lymph nodes and thymus. In situ hybridization with the mouse system showed that the transcript was localized in specific regions of the brain, i.e. pyramidal cells in the CA3 subregion of the hippocampus, cerebellar nucleus and Purkinje cells. Among human tumor cells, strong expression of the mRNA was found in MOLT-4 and Jarkat lymphoblastic leukemia cells, Raji lymphoma cells, K-562 chronic myelogeneous leukemia cells, U251 glioma cells, and G361 melanoma cells. Carbohydrate structures synthesized by the sulfotransferase may be involved in various aspects of the differentiation and behavior of blood cells, their progenitor cells, and neurons in the central nervous system.

Feasibility of double-expression retroviral vector using complement regulatory factor gene

The donor source of vascular endothelial cells for hybrid blood vessels seeded with genetically engineered endothelial cells is generally considered to be autologous. The purpose of this study was to determine whether porcine endothelial cells transduced with double-expression retroviral vector using complement-resistant gene could be substituted for autologous endothelial cells. Decay-accelerating factor (DAF) and tissue plasminogen activator (tPA) cDNA were inserted into retroviral vector with homologous restriction factor 20 cDNA as a complement regulatory factor gene. Porcine aortic endothelial cells were transduced with these double-expression retroviral vectors, followed by the complement-dependent selection. Porcine endothelial cells transduced withdouble-expression retroviral vectors showed a high gene expression of both DAF and tPA. Complement-dependent cytotoxicity and adherence of U937 were significantly inhibited by the transduction of double-expression vectors with complement regulatory factor gene. Double-expression retroviral vector using complement regulatory factor gene was efficacious in substituting porcine endothelial cells for the autologous endothelial cells.

Role of positron emission tomography using fluorine-18 fluoro-2-deoxyglucose in predicting improvement in left ventricular function in patients with idiopathic dilated cardiomyopathy

Improvement in left ventricular (LV) function in patients with idiopathic dilated cardiomyopathy (DCM) by medical treatment has been suggested. Thus, it is important to evaluate which patients will respond to medical therapy. Positron emission tomography (PET) with fluorine-18 fluoro-2-deoxyglucose (FDG) and cardiac catheterization were performed in 20 patients with DCM before the initiation of medical therapy. The regional myocardial glucose utilization rate (rMGU) was measured with FDG PET. Subjects were divided into two groups, group 1 (event-free patients, n=10) and group 2 (clinical cardiac events, n=10). Haemodynamic and PET parameters before the initiation of medication were compared between the two groups and between patients with and patients without improvement in LV function. Ejection fraction (EF) was significantly higher in group 1 (35.8%+/-9.0%) than in group 2 (24.8%+/-7.0%) and LV end-diastolic pressure (LVEDP) was significantly lower in group 1 (8.4+/-1.7 mmHg) than in group 2 (11.6+/-3.5 mmHg). Average rMGU (mg min-1 100 g-1) was similar in group 1 (11.2+/-2.5 mg min-1 100 g-1) and group 2 (11.2+/-2.9 mg min-1 100 g-1), while %CV of rMGU was significantly lower in group 1 (11.1%+/-6.3%) than in group 2 (29. 9%+/-13.9%, P<0.01). Furthermore, LV function normalized in seven patients in group 1. In these seven patients, EF (35.1%+/-10.9%), LVEDP (8.2+/-2.0 mmHg) and average rMGU (11.8+/-2.7 mg min-1 100 g-1) were comparable with those in patients without LV functional improvement (EF: 31.6%+/-9.1%; LVEDP: 10.7+/-3.3 mmHg; average rMGU: 10.8+/- 2.7 mg min-1 100 g-1). However,% CV of rMGU in patients with LV functional improvement (9.6%+/-5.6%) was significantly lower than in those without such improvement (26.3%+/-14.1%, P<0.01). %CV of rMGU <13.6% predicted prognosis with a sensitivity of 80%, a specificity of 100% and an accuracy of 90%. %CV of rMGU <13.6% also predicted improvement in LV function, with a sensitivity of 75%, a specificity of 92% and an accuracy of 85%. However, EF failed to predict improvement of LV function. In is concluded that homogeneous myocardial glucose utilization rate can predict both prognosis and improvement in LV function achieved by medical therapy in patients with DCM.

Changes in intracellular Ca2+ concentrations related to PDT-induced apoptosis in photosensitized human cancer cells

For photodynamic therapy (PDT), human squamous cell carcinoma cells (HSC-2) were treated with 3 microg/ml of photofrin 24 h prior to irradiating the cultures with the excimer dye laser at a dose of 2 J/cm2. Extensive DNA fragmentation was recognized within 2 h of PDT. The proportion of cells with DNA fragmentation on flow cytometric analysis was significantly increased to 44 and 78% at 1 and 2 h after PDT, respectively, compared to control groups. Confocal laser scanning microscopy revealed a slight change in the intracellular Ca2+ concentration occurring at 30 min after PDT and a subsequent marked increase in the Ca2+ concentration 1-2 h after PDT, but no change was observed in the cells exposed to laser irradiation alone and to photofrin alone and in the cells immediately after PDT. These findings suggest that an increase in the intracellular Ca2+ concentration may play an important role in the induction of PDT-induced apoptosis.

Porcine alpha-1,3-galactosyltransferase: full length cDNA cloning, genomic organization, and analysis of splicing variants

Full length cDNA and genomic DNA of porcine alpha-1,3-galactosyltransferase were isolated, and their structures were analysed. The coding region was encoded by six exons as in the mouse, and the length of each exon was conserved between the two species. The porcine exons were designated Exon 4-9, since in the mouse coding exons started from Exon 4. Introns tended to be longer in the porcine gene; the distance from Exon 4 to the 3'-end of Exon 9 was 24 kb, while this region was 18 kb in the mouse gene. The cDNA structure was extended from the previous data to the 3'-end and to the 5' side of the cDNA. In addition to a cDNA clone with all coding exons, clones lacking parts of these exons were isolated and their structures were determined. One variant lacked Exon 5; the second, Exons 5 and 6; and the third, Exons 5, 6 and 7. The last variant was not found in the mouse, and cDNA transfection of this variant yielded scarcely any enzymatic activity using asialo alpha1-acid glycoprotein as a substrate, and decreased activity using N-acetyllactosamine as a substrate.

Impaired myocardial vasodilation during hyperemic stress with dipyridamole in hypertriglyceridemia

OBJECTIVES

This study sought to investigate the specific role of hypertriglyceridemia in the myocardial hyperemic stress with dipyridamole/rest flow ratio (MDR).

BACKGROUND

Reduced MDR has been reported in hypercholesterolemic patients without evidence of ischemia. However, the specific role of hypertriglyceridemia in MDR has not been studied.

METHODS

Fifteen nondiabetic normocholesterolemic hypertriglyceridemic patients and 13 age-matched control subjects were studied. Myocardial blood flow (MBF) during dipyridamole administration and baseline MBF in hypertriglyceridemic patients and control subjects were measured using positron emission tomography and nitrogen-13 ammonia, after which the MDR was calculated.

RESULTS

Baseline MBF (ml/min per 100 g heart weight) in hypertriglyceridemic patients (mean +/- SD 73.6 +/- 24.1) did not differ significantly from that in control subjects (81.6 +/- 37.2). MBF during dipyridamole loading in hypertriglyceridemic patients (198 +/- 106) was significantly reduced compared with that in control subjects (313 +/- 176, p < 0.05), as was the MDR (2.71 +/- 1.07 vs. 3.73 +/- 1.14, respectively, p < 0.05). Spearman rank-order correlation analysis showed a significant relation between plasma triglyceride concentration and MDR (r = -0.466, asymptotic SE 0.157, p = 0.0125); however, no such significant relation was seen between total plasma cholesterol concentration and MDR (r = -0.369, asymptotic SE 0.130, p = 0.059).

CONCLUSIONS

Impaired myocardial vasodilation was suggested in hypertriglyceridemic patients without symptoms and signs of ischemia.

Relationship between recurrence of gastric ulcer and the microcirculation

We investigated the relationship between microcirculatory disturbance and the host response to Helicobacter pylori infections in gastric ulcer scars to determine the role of endothelin-1 (ET) in ulcer recurrence. The subjects were divided into three groups. The GuS group consisted of patients who had red scarring (S1 stage) at the gastric angle with H. pylori, the gast+ group who had gastritis with H. pylori, and the gast- group who had gastritis without H. pylori. During endoscopic examination, biopsies were taken from the gastric angle. Mucosal ET, nitric oxide (NO), interleukin-8 (IL-8), and RANTES were measured. ET, inducible NO synthase (iNOS), and endothelial constitutive NOS (ecNOS) were immunostained. Mucosal ET and oxides of nitrogen (NOx) were significantly higher in the GuS group than in the other groups. IL-8 was elevated in the GuS and gast+ groups, and RANTES was elevated in the gast+ group (p < 0.01). There was prominent inflammatory cell infiltration in the GuS group. ET-positive cells were found in vascular smooth muscle, gastric epithelium, and gastric smooth muscle. iNOS-positive cells were found in vascular smooth muscle, gastric epithelium, gastric smooth muscle, and inflammatory cells. In conclusion, local inflammation and microcirculatory disturbance persist at the center of the ulcer scar (S1). Decreased cytokine levels and increased ET and NO (mainly synthesized by iNOS) levels suggested that microcirculatory disturbance is a more important factor than immune response in ulcer recurrence.

Organ-specific insulin resistance in patients with noninsulin-dependent diabetes mellitus and hypertension

Abnormal heart and skeletal muscle glucose metabolism in diabetes or essential hypertension has been demonstrated. However, the role of hypertension in heart and skeletal muscle glucose utilization in diabetes has not been clarified yet.

METHODS

We compared heart and skeletal muscle glucose utilization using PET and the whole-body glucose disposal rate (GDR) during insulin clamping in 9 patients with noninsulin-dependent diabetes mellitus (NIDDM) and essential hypertension and 11 patients with NIDDM without hypertension to examine the effect of hypertension on heart and skeletal muscle glucose utilization. Results also were compared with those for 8 asymptomatic healthy control participants.

RESULTS

Skeletal muscle glucose utilization rate was comparable between hypertensive NIDDM patients (61.2 +/- 55.5 micromol x min(-1) x kg(-1)) and normotensive NIDDM patients (50.9 +/- 25.2 micromol x min(-1) x kg(-1)) but was significantly reduced in both groups compared with control subjects (94.2 +/- 57.3 micromol x min(-1) x kg(-1)), as was the GDR (25.2 +/- 11.3 and 24.0 +/- 7.5 micromol x min(-1) x kg(-1)), respectively, for patients compared with 38.5 +/- 11.5 micromol x min(-1) x kg(-1) for control participants). However, the myocardial glucose utilization (MGU) rate was significantly reduced in NIDDM patients without hypertension (389 +/- 185 micromol x min(-1) x kg(-1)) than in those with hypertension (616 +/- 86.4 micromol x min(-1) x kg(-1), p < 0.01). Multivariate stepwise regression analysis has shown that MGU was significantly correlated with systolic blood pressure and plasma free fatty acid concentration.

CONCLUSION

Whole-body insulin resistance was observed in NIDDM patients independent of hypertension. The MGU rate may have different properties to oppose insulin resistance than glucose utilization of skeletal muscle in hypertensive patients with NIDDM.

Establishment of a concordant xenogeneic splenocyte injection model for the dynamic study of the marginal zone in the spleen

BACKGROUND

This study was undertaken to establish a simple technique with which we could investigate the relationship between the marginal zone (MZ) in the spleen and antispecies antibody production, as well as to estimate the efficacy of various immunosuppressive treatments in xenotransplantation.

METHODS

With a concordant xenogeneic combination (hamster-to-rat), the early phase reaction of the MZ was studied by use of quantitative histologic analysis, and complement-dependent cytotoxic antibody titers were determined in both a heart transplantation model and the splenocyte injection model. Furthermore, changes in the MZ were examined with isogeneic and allogeneic combinations with the splenocyte injection model. Next, the effect of cyclophosphamide, a promising immunosuppressant for concordant xenotransplantation, was examined by use of the splenocyte injection model.

RESULTS

With a concordant xenogeneic combination, the MZ enlarged, and antihamster immunoglobulin M antibody synthesis increased after immunization in both models. On the other hand, with an isogeneic combination, the MZ did not expand, and with an allogeneic combination the MZ enlargement was not as great as that with a concordant xenogeneic combination. Cyclophosphamide suppressed the MZ expansion in a dose-dependent manner and effectively diminished antibody production in the splenocyte injection model.

CONCLUSION

Dynamic studies of the MZ in the spleen with the splenocyte injection model are useful for the elucidation of the mechanisms of reaction and for estimating the efficacy of various immunosuppressive treatments in concordant xenotransplantation.

Altered myocardial vasodilatation in patients with hypertriglyceridemia in anatomically normal coronary arteries

Reduced myocardial vasodilatation (MVD) in hypercholesterolemics without overt coronary stenosis has been reported. However, the status of MVD in hypertriglyceridemics has not yet been clarified. The aim of this study was to investigate whether MVD is impaired in patients with hypertriglyceridemia without overt coronary stenosis. Twenty-three hypertriglyceridemics (10 normocholesterolemic hypertriglyceridemics [HTGs] and 13 mixed combined hyperlipidemics [MCHLs]) and 13 age-matched controls were studied. All patients were proven to have more than one normal coronary artery, as diagnosed by coronary angiography, and those segments that were perfused by anatomically normal coronary arteries were used in the study. Myocardial blood flow (MBF) during dipyridamole (DP) loading and baseline MBF were measured by using positron emission tomography and [13N]ammonia, after which MVD was calculated. Baseline MBF (mL.min(-1).100 g(-1)) was comparable among HTG (76.0+/-26.1), MCHL (77.0+/-26.1), and controls (80.3+/-38.5). However, MBF during DP loading was significantly lower in MCHL (159+/-52.5) than in control subjects (292+/-166, P<.01), while it was comparable in HTG (202+/-104) and controls. MVD was significantly reduced in both HTG (2.70+/-1.09, P<.05) and MCHL (2.07+/-.70, P<.01) compared with controls (3.73+/-1.14). MVD in MCHLs tended to be reduced compared with that in HTGs, but the difference was statistically insignificant (P=.08). There was a significant relationship between MVD and both plasma triglycerides (r=-.47, P<.01) and plasma total cholesterol (r=-.55, P<.01). When controls and HTGs were combined, the relationship between MVD and plasma total triglycerides became more prominent (r=-.55, P<.05), and the significant relationship between cholesterol level and MVD disappeared. Multivariate regression analysis has revealed that the triglyceride level (F=5.2, P<.05) was independently related to MVD (r=.69, P<.01). In conclusion, MVD was reduced in hypertriglyceridemics in anatomically normal coronary arteries. Hypertriglyceridemia is an independent factor for this abnormality.

Establishment of complement-resistant retroviral vector by homologous restriction factor 20 gene

Homologous restriction factor 20 (HRF20, CD59) is one of the complement regulatory factors. In this study, the complement-resistant retroviral vector, which possesses the HRF20 gene as a selection gene, was constructed and examined. The virus-producing cell, transduced with complement-resistant retroviral vector, was established after complement-dependent selection. NIH3T3 and PK15 cells transduced with this virus-producing cell were successfully selected by complement-dependent selection, which showed significant expression of the HRF20 antigen. In addition, these cells, transduced with tissue plasminogen activator (tPA) cDNA using complement-resistant retroviral vector, expressed tPA antigen after complement-dependent selection. These findings suggest that complement-resistant retroviral vector can be used for the double transduction of HRF20, as well as other genes.

Hyperglycemia rather than insulin resistance is related to reduced coronary flow reserve in NIDDM

To clarify if coronary flow reserve (CFR) is related to insulin resistance or hyperglycemia in normotensive NIDDM, myocardial blood flow (MBF) at baseline and during dipyridamole loading were measured with 13N-ammonia positron-emission tomography. CFR was significantly reduced in NIDDM patients compared with age-matched control subjects. CFR in patients with well-controlled NIDDM was significantly higher than in those with poorly controlled NIDDM, whereas insulin resistance was comparable between the two groups. CFR in NIDDM patients was not related to the degree of insulin resistance. CFR correlated significantly with average fasting glucose concentration and average HbA1c, but not with insulin resistance, age, lipid parameters, or blood pressure. In conclusion, control of blood glucose concentration rather than insulin resistance is most likely related to the reduced CFR in NIDDM.

Fas antigen expression of hepatocytes and its modification by immunosuppressants

Active cell death induced by ligation of the Fas antigen (Fas-Ag) with its antibody, Fas ligand (Fas-L), has been known to play a major role in cell killing via apoptosis by cytotoxic T lymphocytes (CTL). Thus, in liver transplantation, Fas-Ag expression of hepatocytes and its modification by immunosuppressive agents such as FK 506 or CsA can theoretically influence allograft survival. Mouse hepatocytes (BALB/c) were isolated and cultured with or without FK 506 or CsA, and Fas-Ag expression was determined by flow cytometry. Fas-Ag expression in the control was 17.2 +/- 2.5% after 24 hr of culture. When FK 506 or CsA was added, Fas-Ag expression with FK 506 at a concentration of 0.01-0.1 microg/ml was significantly lower than that with CsA (P < 0.05). When the cells were incubated with apoptosis-inducing anti-Fas-Ag monoclonal antibody, agarose gel electrophoresis of the control cells yielded a typical pattern of DNA fragmentations. The cells with FK 506 at 0.01 microg/ml yielded the least DNA fragmentation. These findings suggested that in the in vivo setting, the hepatocytes of the allograft would have a lower chance of being attacked by CTL in the host treated with FK 506.