Changes in vasoactive substances during gastric ulcer healing

In order to study the roles of vasoactive peptides during tissue repair of gastric ulcers, we compared concentrations in tissue surrounding gastric ulcers of endothelin-1(ET-1), adrenomedullin (AM), and transforming growth factor-beta (TGF-beta) among different stages of ulcer development. A total of 82 cases were studied. Ulcers were located in the gastric angulus in 51 cases. All cases were positive for Helicobacter pylori (Hp). Ten cases were in the active stage (GA), 18 were in the healing stage (GH), and 28 were in the scarring stage (GS). As control, 17 cases of Hp-positive gastritis (gast+) and 14 of Hp-negative gastritis (gast-) were studied. The concentrations of endothelin (ET) and TGF-beta were in the order of GH> GA> GS, and those of AM were in the order of GS > GH > GA. On immunostaining, ET stained positively in endothelial cells and vascular smooth muscle cells (VSMCs) during the GH and GS stages, and AM stained positively in histiocytes during GA, GH and GS, and also stained positively in glandular epithelia and smooth muscle fibers during GH and GS. When our results were reviewed with respect to the regulation of vascular tonus and the proliferation of VSMCs, ET and AM were considered to have roles in the regulation of proliferation.

Changes of nitric oxide and growth factors during gastric ulcer healing

We measured the concentrations of vascular endothelial growth factor (VEGF), nitric oxide and endothelin-1 (ET-1) in the gastric mucosa and examined the relationships between these factors. VEGF, nitric oxide and ET participate in angiogenesis and vascular remodeling, important elements of gastric ulcer healing. We studied cases of gastric ulcer as confirmed by endoscopic examination. All 61 cases in the angulus were positive for Helicobacter pylori (Hp). Fifteen cases were active stage (GA), 23 were healing stage (GH), and 23 were scarring stage (GS). As control, 17 cases of Hp-positive gastritis (gast+) and 14 cases of Hp-negative gastritis (gast-) were studied. Biopsy samples taken from the angulus during endoscopic examination were frozen and sliced into thin sections. ET was measured by enzyme immunoassay, VEGF was measured by enzyme-linked immunosorbent assay (ELISA) and nitric oxide was measured in terms of metabolite oxides of nitrogen (NOx) as described by Griess. ET, VEGF and inducible nitric oxide synthase (iNOS) were immunostained. The GA group had the highest concentration of NOx, suggesting that nitric oxide participates in the early stage of mucosal repair. In the GH group, all three factors showed high concentrations, suggesting that all may be involved in increased production. In the GS group, all three factors were significantly lower than in the GA and GH groups. Immunohistochemical studies showed that the distribution of ET- and iNOS-positive cells differed according to the ulcer stage. In particular, ET- and iNOS-positive cells in the vascular wall were primarily endothelial cells during GA and GH and vascular smooth muscle cells (VSMCs) during GS. These findings suggest that endothelial cells produce increased amounts of ET, nitric oxide and VEGF early in ulcer healing, a period of active endothelial cell repair and angiogenesis. During the scarring stage, vascular remodeling may result from the effects of ET and nitric oxide in regulating the proliferation of VSMCs. Our results suggest that VEGF. nitric oxide and ET participate in angiogenesis, vascular remodeling and mucosal regeneration during ulcer healing.

Protection of xeno-hepatocytes from complement-mediated cytolysis by transduction with homologous restriction factor 20 gene using retroviral vector

Xeno-hepatocyte transplantation has the possibility to substitute for clinical liver transplantation in certain restricted hepatic diseases such as inherited metabolic disorders. To overcome human complement-dependent cytotoxicity on xeno-hepatocytes, the effectiveness of ex vivo transfer with the homologous restriction factor 20 (HRF20, CD59) gene was examined on primary-cultured xeno-hepatocytes using a retroviral vector. Primary-cultured rat hepatocytes transduced with HRF20 cDNA expressed HRF20 antigen by flow cytometric analysis and showed the integration of HRF20 cDNA to the genomic DNA by the polymerase chain reaction. The viability of rat hepatocytes incubated with 50% human serum was decreased due to complement-dependent cytotoxicity, whereas that of the transfectant was significantly protected (77.2+/-9.4 vs. 97.8+/-5.2%, p < 0.01). It was concluded that primary-cultured xeno-hepatocytes transduced with HRF20 cDNA using a retroviral vector could escape complement-dependent cytolysis by human serum.

Inhibition of carnitine synthesis modulates protein contents of the cardiac sarcoplasmic reticulum Ca2+-ATPase and hexokinase type I in rat hearts with myocardial infarction

It was previously reported that inhibition of carnitine synthesis by 3-(2,2,2-trimethyl-hydrazinium) propionate (MET-88) restores left ventricular (LV) systolic and diastolic function in rats with myocardial infarction (MI). Preservation of the calcium uptake function of sarcoplasmic reticulum Ca2+-ATPase (SERCA2) is one of the possible mechanisms by which MET-88 alleviates hemodynamic dysfunction. To test this hypothesis, the effects of MET-88 on protein content of SERCA2 were evaluated using the same rat model of heart failure. Myocardial protein content of hexokinase, which is one of the key enzymes of glucose utilization, was also measured. Either MET-88 (MET-88 group) or a placebo (MI group) was administered for 20 days to rats with MI induced by coronary artery ligation. The control group underwent sham surgery (no ligation) and received placebo. In LV myocardial homogenates, the myocardial SERCA2 protein content was 32% lower (p<0.05) in the MI group than in the control group. However, in the MET-88 group myocardial SERCA2 content was the same as in the control group. Hexokinase I protein content was 29 % lower (p<0.05) in the MI group compared with the control. In contrast, hexokinase II protein content did not differ significantly among the three groups. Consequently, inhibition of carnitine synthesis ameliorates depression of SERCA2 and hexokinase I protein content which may reduce tissue damage caused by MI.

Estimation of 99mTc-MAG3 clearance by single-sample methods and camera-based methods

We compared single-sample methods, proposed by Russell et al. and Bubeck et al., and camera-based methods in calculating 99mTc-MAG3 clearance, and determined camera-based methods that provide estimates comparable to those measured by the Russell method. Twenty-one patients underwent 99mTc-MAG3 renal scintigraphy, and clearance was measured by the Russell method and Bubeck method. Various renogram parameters were determined based on the slope of the renogram and area under the renogram, and correlated with the clearance measured by the Russell method. Camera-based clearance was calculated with the obtained regression equations and with equations determined previously using the Bubeck method as a standard. The Bubeck method provided lower measures than the Russell method in high renal function. Clearance measured by the Russell method was well correlated with renogram parameters, and clearance calculated with the obtained regression equation was comparable to that measured by the Russell method. When camera-based clearance was predicted with the previous equation, it was lower than the result obtained by the Russell method in high function. In conclusion, there are systematic differences in 99mTc-MAG3 clearance calculated by different methods. The camera-based methods obtained in this study appear to facilitate comparison of results obtained by the Russell method and camera-based method.

Regional differences in cerebral vascular response to PaCO2 changes in humans measured by positron emission tomography

Hypercapnia and hypocapnia produce cerebral vasodilation and vasoconstriction, respectively. However, regional differences in the vascular response to changes in Paco2 in the human brain are not pronounced. In the current study, these regional differences were evaluated. In each of the 11 healthy subjects, cerebral blood flow (CBF) was measured using 15O-water and positron emission tomography at rest and during hypercapnia and hypocapnia. All CBF images were globally normalized for CBF and transformed into the standard brain anatomy. t values between rest and hypercapnia or hypocapnia conditions were calculated on a pixel-by-pixel basis. In the pons, cerebellum, thalamus, and putamen, significant relative hyperperfusion during hypercapnia was observed, indicating a large capacity for vasodilatation. In the pons and putamen, a significant relative hypoperfusion during hypocapnia, that is, a large capacity for vasoconstriction, was also observed, indicating marked vascular responsiveness. In the temporal, temporo-occipital, and occipital cortices, significant relative hypoperfusion during hypercapnia and significant relative hypoperfusion during hypocapnia were observed, indicating that cerebral vascular tone at rest might incline toward vasodilatation. Such regional heterogeneity of the cerebral vascular response should be considered in the assessment of cerebral perfusion reserve by hypercapnia and in the correction of CBF measurements for variations in subjects' resting Paco2.

Lack of antibody production against Hanganutziu-Deicher (H-D) antigens with N-glycolylneuraminic acid in patients with porcine exposure history

The significance of non-alphagalactosyl antigens remains unclear in pig-to-primate xenotransplantation. Hanganutziu-Deicher (H-D) antigens with terminal N-glycolylneuraminic acid (NeuGc) are widely expressed on endothelial cells of mammalian species, with the exception of humans. As baboons and monkeys also express H-D antigens, a pig-to-non-human primate experimental model cannot resolve the question of whether H-D antigens can elicit a potent humoral response in human recipients. The purpose of this study was to elucidate the clinical significance of H-D antigens by examining the sera from patients who have been previously exposed to porcine tissue. After the digestion of porcine aortic endothelial cells (PAEC) by neuraminidase, NeuGc and N-acetylneuraminic acid (NeuAc) were quantitated by HPLC. IgG and IgM antibody levels against H-D antigens were measured by NeuGc-GM3-coated ELISA plates in the sera of patients who had undergone ex vivo kidney perfusion 1 to 3 weeks and 2 years previously (n=2) or had been injected with fetal porcine islets 2 months previously (n= 10). HPLC determined that 9.7x 10(7) NeuAc and 6.3x 10(7) NeuGc residues per cell were released from PAEC by neuraminidase, while 25.7x 10(7) NeuAc and an undetectable level of NeuGc were released from human aortic endothelial cells (HAEC). No significant elevation of IgG or IgM antibody levels against NeuGc-GM3 was observed in sera from patients with a history of porcine exposure. Considering the active production of antibody against the foreign galactosyl antigens after pig-to-human xenotransplantation, some production of antibodies against the equally foreign H-D antigens would be expected, because large amounts of NeuGc terminated saccharides are present in the pig endothelial cell surface. However, no production of antibodies directed to H-D antigens could be found in patients exposed to porcine tissue. Further studies are warranted to explain why H-D antigens do not elicit a significant antibody production.

Significance of transporter associated with antigen processing gene polymorphism in living related renal transplantation

The HLA class I and class II mediated antigen presentation plays a major role in the initiation of immune response and the development of acute rejection after transplantation. The purpose of this study was to examine whether MHC-encoded antigen processing (TAP1, TAP2, LMP2, DMA and DMB) gene polymorphisms were associated with the incidence and the severity of acute rejection after renal transplantation. We studied a selected population of 112 pairs of donors and recipients who underwent living-related renal transplantation. They were divided into 3 groups: rejection-free (Group A, n = 51), steroid-sensitive rejection (Group B, n = 31) and steroid-resistant rejection (Group C, n = 30). The frequency of TAP2*0103 (41.2%) was significantly higher in the donors of Group A than that of Group B (12.9%, p = 0.0070, pc = 0.0280) or Group C (16. 7%, p = 0.0225, pc = 0.0900). No significant difference was observed in the allelic frequencies of the TAP1, LMP2, DMA, and DMB genes in the donors or recipients among Groups A, B, and C. This result supported the idea that the TAP2 gene polymorphism might be functionally related to antigen presentation. It also suggested that donor's antigen presenting cells with the TAP2*0103 allele would have the attenuated efficacy in the presentation of allospecific antigens to recipient's T cells.

Molecular cloning of endo-beta -galactosidase C and its application in removing alpha -galactosyl xenoantigen from blood vessels in the pig kidney

Galalpha1-3Gal is the major xenoantigenic epitope responsible for hyperacute rejection upon pig to human xenotransplantation. Endo-beta-galactosidase C from Clostridium perfringens destroys the antigenic epitope by cleaving the beta-galactosidic linkage in the Galalpha1-3Galbeta1-4GlcNAc structure. Based on partial peptide sequences of the enzyme, we molecularly cloned the enzyme gene, which encodes a protein with a predicted molecular mass of about 93 kDa. The deduced protein sequence of the enzyme has limited homology in the C-terminal half with endo-beta-galactosidase from Flavobacterium keratolyticus and beta-1,3-glucanases. The enzyme expressed in Escherichia coli removed the alpha-galactosyl epitope nearly completely from pig erythrocytes and from pig aortic endothelial cells. The enzyme-treated endothelial cells in culture were greatly reduced in cell surface antigens, which were recognized by IgM, IgG, or IgA in human sera, and became much less susceptible to complement-mediated cytotoxicity caused by human sera. When the pig kidney was perfused with the enzyme, the vascular endothelial cells became virtually devoid of the alpha-galactosyl epitope, with concomitant decrease in binding to IgM in human plasma. These results demonstrated that the recombinant endo-beta-galactosidase C is a valuable aid in xenotransplantation.

Case study of paired cadaver renal allografts from the same donor: influence of local DIC kidney and concomitant acute rejection on early graft outcome

We report the clinical course of 2 recipients whose renal allografts were obtained from the same cadaver donor after cardiac arrest. The recipients showed different outcomes after transplantation. Graft biopsy after reperfusion revealed disseminated intravascular coagulation (so-called DIC kidney) and severe acute tubular necrosis (ATN) in both recipients. While one graft showed primary nonfunction, the other graft became functional after a post-operative anuric period. Serial graft biopsies performed during the oligo-anuric period revealed recovery of ATN and no intra-glomerular fibrin thrombi, but development of acute rejection was detected in both recipients. The left kidney graft showed more severe local DIC kidney than the right kidney, as well as more severe acute rejection in the oligo-anuric period. Despite aggressive anti-rejection therapy, the left kidney graft showed primary nonfunction. Therefore, severe acute rejection leading to primary nonfunction might have been related to more severe ischemic injury and more extensive local DIC kidney in the left kidney.

Coronary microangiopathy in type 2 diabetic patients: relation to glycemic control, sex, and microvascular angina rather than to coronary artery disease

Coronary microangiopathy is a major complication in diabetics. However, the presence of independent factors in association with coronary microangiopathy in patients with non-insulin-dependent diabetes mellitus (NIDDM) or the difference in coronary microangiopathy between diabetics with coronary artery disease (CAD) and those with microvascular angina is unclear.

METHODS

Nineteen patients with NIDDM and microvascular angina, 18 patients with NIDDM and CAD, and 17 age-matched control subjects were studied. Myocardial segments that were perfused by angiographically normal coronary arteries were studied. The baseline myocardial blood flow (MBF) and the MBF during dipyridamole administration were measured using PET and 13N-ammonia, after which the myocardial flow reserve (MFR) was calculated to assess coronary microangiopathy.

RESULTS

The baseline MBF was comparable among NIDDM patients with microvascular angina, NIDDM patients with CAD, and control subjects. However, the MBF during dipyridamole administration was significantly lower in NIDDM patients with microvascular angina (126 +/- 42.7 mL/min/100 g) than that in either NIDDM patients with CAD (210 +/- 70.1 mL/min/100 g; P < 0.01) or control subjects (293 +/- 159 mL/min/100 g; P < 0.01), as was the MFR (NIDDM with microvascular angina, 1.90 +/- 0.73; NIDDM with CAD, 2.59 +/- 0.81 [P < 0.01]; control subjects, 3.69 +/- 1.09 [P < 0.01]). Multivariate stepwise regression analysis showed that, among the factors considered, glycemic control was independently related to the MFR (r = 0.838; P < 0.05).

CONCLUSION

Glycemic control appears to be essential for coronary microangiopathy in NIDDM.

Role of insulin resistance in heart and skeletal muscle F-18 fluorodeoxyglucose uptake in patients with non-insulin-dependent diabetes mellitus

BACKGROUND

Altered heart and skeletal glucose usage has been reported in patients with non-insulin-dependent diabetes mellitus (NIDDM). Although elevations in plasma free fatty acid (FFA) concentrations have been implicated in reduced myocardial 18fluorine-fluoro-2-deoxy-D-glucose uptake (MFU), the specific role of whole-body insulin resistance in MFU in patients with NIDDM compared with skeletal muscle metabolism remains controversial.

PURPOSE

MFU and skeletal muscle 18fluorine-fluoro-2-deoxy-D-glucose uptake (SMFU) were compared with positron emission tomography and the whole-body glucose disposal rate (GDR) during hyperinsulinemic euglycemic clamping in 26 normotensive asymptomatic patients with NIDDM who were not taking medication. These factors were also compared in 12 age-matched control subjects to increase the knowledge of the influence of whole-body insulin resistance on MFU. In addition, independent factors for both SMFU and MFU were investigated.

RESULTS

GDR in control subjects (10.0 +/- 2.97 mg/min per kilogram) was significantly higher than in patients with NIDDM (4.05 +/- 2.37 mg/min per kilogram, P < .01). SMFU in patients with NIDDM (0.826 +/- 0.604 mg/min per 100 g) was significantly lower than that in control subjects (1.86 +/- 1.06 mg/min per 100 g, P < .01). MFU in patients with NIDDM (5.35 +/- 2.10 mg/min per 100 g) was also significantly lower than that of control subjects (7.05 +/- 1.66 mg/min per 100 g, P = .0182). SMFU significantly correlated with GDR (r = .727, P < .01) and FFA (r = -.52, P < .01) in patients with NIDDM. MFU also correlated with GDR (r = .778, P < .01) and FFA (r = -.72, P < .01) in patients with NIDDM. Multivariate stepwise regression analysis showed that GDR (F = 36.8) was independently related to MFU (r = .85, P < .01) whereas FFA was not (F = 1.763), where F is the value for statistical analysis of multivariate stepwise regression analysis.

CONCLUSION

Insulin resistance is the most essential factor for both heart and skeletal muscle FDG uptake in patients with NIDDM.

Comparative study of theefficacy of removal of anti-ABO and anti-gal antibodies by double filtration plasmapheresis

Successful clinical ABO-incompatible renal transplantation has been achieved by the removal of anti-A or anti-B antibodies using double filtration plasmapheresis (DFPP). We have compared changes in the levels of anti-donor antibodies and the histopathology of the renal grafts following human ABO-incompatible allotransplantation and pig-to-baboon xenotransplantation using pretransplant DFPP. DFPP was performed on days 6, -4, -2 and -1 before the ABO-incompatible transplants (n=25) and on days -2 and 0 (immediately before reperfusion) in the xenotransplants (n=4). In two baboons (XenoTx Group I) the extent of antibody removal was comparable to that in the ABO-incompatible patients, and an even greater level of removal was achieved in another two baboons (XenoTx Group II). Anti-A and anti-B and anti-pig IgM and IgG antibodies were measured by flow cytometry. All clinical ABO-incompatible renal grafts are functioning, except two which were lost from recurrence of the original disease or from chronic rejection. Three other grafts underwent humoral rejection episodes, which were successfully treated. DFPP reduced the mean anti-A/B IgM and IgG antibody levels to 8% and 13% of pretreatment levels, respectively. After kidney transplantation, they were maintained at 37% and 46% of pre-DFPP level. No antibody binding to the transplanted kidney was detected at any time (1 h to 2 yr) after ABO-incompatible allotransplantation. In contrast, in XenoTx Group I, the same extent of antibody removal (90%) prevented hyperacute rejection, but the two grafts were rejected on days 6 and 7, respectively, from acute vascular rejection. In XenoTx Group II, the additional DFPP that was required to deplete the remaining 10% of anti-pig antibody was poorly tolerated and the two baboons died 4 h and 2 days, respectively, after renal transplantation. Although anti-pig IgM antibodies were reduced to 2% of pre-treatment level, IgM and C3 binding were detected in the graft as early as 1 h posttransplantation. These data suggest that the concentration of xeno-antigen epitopes expressed on pig organs may need to be reduced by genetic engineering to the much lower level of blood group A/B antigens on human kidneys if discordant xenotransplantation is to be successful.

Attenuation correction in evaluating renal function in children and adults by a camera-based method

Correction for soft-tissue attenuation is required to evaluate absolute renal function by a camera-based method, and an estimate of renal depth and an attenuation coefficient are commonly used for attenuation correction. The first goal of this study was to develop formulas for the calculation of renal depth in both children and adults. The second goal was to optimize the attenuation coefficient for the estimation of renal accumulation of a 99mTc-labeled agent.

METHODS

Renal depth was measured by CT in 74 children and 232 adults and compared with the depth calculated using previously published equations. Multiple stepwise linear regression analysis was conducted using data from children and adults together, and new formulas to calculate renal depth were derived. Using the resulting equations, percentage renal uptake at 2-2.5 min was computed from 99mTc-diethylenetriamine pentaacetic acid (DTPA) renography in 40 children and 92 adults. Percentage renal uptake was assessed using various values of an attenuation coefficient, and an optimized attenuation coefficient was determined to maximize the correlation coefficient between percentage renal uptake and glomerular filtration rate (GFR) measured from 2 blood samples.

RESULTS

Although the previously published equations appeared to be acceptable in predicting adult renal depth, they substantially underestimated pediatric renal depth. Renal depth (D, cm) was shown by stepwise regression analysis to depend on the ratio of body weight (W, kg) to body height (H, cm) and was successfully calculated in both children and adults using the derived equations (right: D = 16.778 x W/H + 0.752; left: D = 16.825 x W/H + 0.397). The correlation coefficient between percentage renal uptake of 99mTc-DTPA and measured GFR varied substantially according to the attenuation coefficient used and was the highest (0.947) with an attenuation coefficient of 0.087/cm.

CONCLUSION

The equations presented here enabled estimation of renal depth irrespective of the patient's age. Attenuation correction using these equations and the optimized attenuation coefficient appears to aid in evaluating renal accumulation and, consequently, renal function in both children and adults.

A synthetic peptide of human apoprotein E with antibacterial activity

In recent years, several endogenous mammalian antibacterial peptides have been described. An amphipathic cationicalpha-helix is a common feature in many cases; therefore, other peptides with this characteristic might also possess antibiotic activity. In fact, a 30-mer peptide of apoprotein E 133-162 (LRVRLASHLRKLRKRLLRDADDLQKRLAVY) was found to have antibiotic activity comparable to those of a classic antibiotic (Gentamicin) and a neutrophil-derived antibiotic peptide (CAP18). Calculation of cationicity, hydrophobicity, and hydrophobic moment and the helical wheel diagram of apoprotein E 133-162 revealed close similarities to CAP18.