Kinetic study of racemization of aspartyl residues in model peptides of alpha A-crystallin

We have reported that two aspartyl (Asp-151 and Asp-58) residues in alpha A-crystallin in human eye lens were inverted to the D-isomer and isomerized to beta-aspartyl residues with age. We report here the kinetics of the Asp racemization of three model peptides corresponding to fragments of alpha A-crystallin: IQTGLD151ATHAER (T18 peptide), TVLD58SGISEVR (T6 peptide) and HFSPED84LTVK (T10 peptide, as a control). The rate constants of the racemization of Asp residues in these peptides were measured at pH 7.0, at five temperatures: 50, 60, 70, 80 and 90 degrees C. From the Arrhenius equation, we estimated the activation energy (E) of racemization and the time required for the Asp D/L ratio to approximate to 1.0 (D/L ratio of Asp = 0.99) at body temperature. For the peptide T18, E = 21.4 kcal/mol and t = 13.5 yr. For the peptide T6, E = 26.8 kcal/mol and r = 49.5 yr. For the control peptide T10, E = 28.3 kcal/mol and t = 78.1 yr. The racemization rate of Asp in these three peptides is parallel to that of Asp residues in alpha A-crystallin. The racemization rate of Asp in the T18 peptide was very rapid compared to that in the other peptides. This result also reflects the racemization rate in native alpha A-crystallin.

Detection of transforming growth factor-alpha protein and messenger RNA in hepatobiliary diseases by immunohistochemical and in situ hybridization techniques

Transforming growth factor-alpha (TGF-alpha) is a cytokines related to cell proliferation and transformation. Immunoreactive TGF-alpha protein is expressed in regenerating hepatocytes and interlobular bile ducts as well as in hepatocellular carcinoma. Although TGF-alpha is thought to play an important role in the intrahepatic biliary tree, its role in cellular physiology is poorly understood. This study investigates the expression of TGF-alpha and its messenger RNA (mRNA) in various hepatobiliary diseases. The authors showed by immunohistochemistry that TGF-alpha and its receptor, epidermal growth factor receptor (EGFR), were expressed in interlobular bile ducts, proliferating bile ductules, and most hepatocytes in various hepatobiliary liver tissues. They also showed by Western blot analysis that TGF-alpha protein was present in hepatic bile samples obtained from patients with obstructive jaundice. In situ hybridization showed that TGF-alpha mRNA was localized in hepatocytes of some pathological liver tissues, but it was absent in biliary epithelial cells of the same tissues. These findings suggest that TGF-alpha protein is produced by hepatocytes, and hepatocyte stimulation occurred as autocrine growth regulation. The release of TGF-alpha into hepatic bile caused biliary proliferation and transformation through EGFR, present on the existing cell surface membrane of biliary epithelial cells.

Suppression of diet-induced atherosclerosis in low density lipoprotein receptor knockout mice overexpressing lipoprotein lipase

Lipoprotein lipase (LPL) is a key enzyme in the hydrolysis of triglyceride-rich lipoproteins. Conflicting results have been reported concerning its role in atherogenesis. To determine the effects of the overexpressed LPL on diet-induced atherosclerosis, we have generated low density lipoprotein receptor (LDLR) knockout mice that overexpressed human LPL transgene (LPL/LDLRKO) and compared their plasma lipoproteins and atherosclerosis with those in nonexpressing LDLR-knockout mice (LDLRKO). On a normal chow diet, LPL/LDLRKO mice showed marked suppression of mean plasma triglyceride levels (32 versus 236 mg/dl) and modest decrease in mean cholesterol levels (300 versus 386 mg/dl) as compared with LDLRKO mice. Larger lipoprotein particles of intermediate density lipoprotein (IDL)/LDL were selectively reduced in LPL/LDLRKO mice. On an atherogenic diet, both mice exhibited severe hypercholesterolemia. But, mean plasma cholesterol levels in LPL/ LDLRKO mice were still suppressed as compared with that in LDLRKO mice (1357 versus 2187 mg/dl). Marked reduction in a larger subfraction of IDL/LDL, which conceivably corresponds to remnant lipoproteins, was observed in the LPL/LDLRKO mice. LDLRKO mice developed severe fatty streak lesions in the aortic sinus after feeding with the atherogenic diet for 8 weeks. In contrast, mean lesion area in the LPL/LDLRKO mice was 18-fold smaller than that in LDLRKO mice. We suggest that the altered lipoprotein profile, in particular the reduced level of remnant lipoproteins, is mainly responsible for the protection by LPL against atherosclerosis.

Role of gestational age and body weight on Doppler transmitral flow velocity pattern in very low birth weight infants

Doppler transmitral flow velocity was measured in premature infants. The early diastolic peak velocity, the peak velocity of early diastole/peak velocity of atrial contraction ratio, and total flow velocity-time integral increased significantly with advancing gestational age and body weight. The peak filling rate normalized to stroke volume (NPFR) did not correlate with gestational age or body weight. Moreover, mean NPFR was not significantly different between premature and term infants. Thus NPFR demonstrates that changes in the left ventricular filling patterns with advancing gestational age and increasing body size are related to the progressive increase in loading conditions, rather than to sequential changes in myocardial properties.

Microcystin levels during 1992-95 for Lakes Sagami and Tsukui-Japan

Toxic cyanobacterial blooms have been frequently observed in Lakes Sagami and Tsukui, Kanagawa Prefecture, Japan, which are used as drinking and recreational water sources. As the first step toward the control and removal of cyanobacterial toxins, the present study evaluated the microcystin level in these lakes. Our established method using HPLC and LC/MS to pursue trace amounts of microcystins was applied to the determination of microcystins within cyanobacteria cells and in water. We could determine precisely the intracellular and extracellular microcystin level in the water environment during 1992-95. Microcystins RR, LR, and YR were detected at 0.02-2.64 micrograms/L in cell-free water and at 0.02-378 micrograms/L in the cells. Although there were many cases in which microcystin concentrations in the cells exceeded the proposed guideline level (1 microgram/L), there was only one example of this happening in cell-free water samples. Because the present monitoring indicated that the amount of microcystins detected in water was much less than that estimated in cells, the release of microcystins from the cells and their stability in lake water were examined in the dark. The resulting toxins persisted at the same concentration level for 14 days and the microcystin concentrations steadily declined, showing that biodegradation using aquatic natural bacterial flora is an effective detoxification process under natural conditions.

Effects of low-dose dobutamine on left ventricular diastolic filling in children

To investigate the effects of dobutamine on the Doppler transmitral flow pattern in children with normal left ventricular function, Doppler echocardiography was used to measure the transmitral flow in 14 healthy children before and during infusion of dobutamine (5 micrograms/kg per minute). Cardiac output was measured by the thermodilution method, and stroke volume was calculated as the cardiac output divided by the heart rate. Dobutamine increased the peak velocity and flow velocity-time integral of early diastolic filling without changing those of atrial contraction and normalized peak velocity of early diastolic filling, suggesting an increase in left ventricular relaxation. Dobutamine increased the stroke volume and rate-corrected mean velocity of fiber shortening with reduced end-systolic wall stress, indicating an increase in left ventricular contractility. The percentage of increase in the flow velocity-time integral of early diastolic filling during dobutamine infusion tended to correlate with the increase in stroke volume (r = 0.67, p < 0.05) and with the decrease in end-systolic wall stress (r = -0.61, p < 0.05). Our results suggest that low-dose dobutamine increases left ventricular relaxation with enhanced systolic function. The observed decreased endsystolic wall stress might have caused enhanced relaxation characteristics with dobutamine.

Transgenic mouse and gene therapy

In the transgenic mouse, a specific gene can be transduced or deleted to study its function and relation to human diseases. Recently, various lines of transgenic mice that overexpress or lack a specific gene have been established and are available to study the pathophysiology of human diseases, including atherosclerosis, diabetes, and hyperlipidemia. We have established transgenic mouse lines with an integrated rat apolipoprotein (apo) E gene under control of the metallothionein promoter. Overexpression of apoE in the liver reduced plasma cholesterol and triglyceride levels and prevented diet-induced hypercholesterolemia. Another transgenic model with overexpression of apoE under control of the H2 Ld promoter in the arterial wall was established. In this model, the formation of fatty streak lesions was markedly inhibited, suggesting that apoE has antiatherogenic actions. Finally, we discuss gene therapy, which will be an important therapeutic approach to correct genetic abnormalities found in metabolic diseases.

An infant case of Ebstein's anomaly of the tricuspid valve with abnormal diastolic filling pattern of the left ventricle

We report herein an infant case of Ebstein's anomaly with abnormal diastolic filling pattern of the left ventricle. We also compare the case with a comparable case without such abnormal filling pattern. The patient, who had pulmonary valve stenosis, patent ductus arteriosus and mild mitral regurgitation, underwent transventricular valvotomy at 30 days of age. Postoperative course was uneventful. Serial Doppler echocardiographic studies were performed at 2 hr, 40 days, and 52 days of age. Peak velocity and flow velocity-time integral of early diastole, and ratios of the peak velocities and velocity time integrals of the early diastole and atrial contraction were below the 95% confidence limits of the normal controls. Our case suggests that left ventricular diastolic dysfunction may exist in the Ebstein's anomaly when it is associated with mitral valve abnormality such as mitral regurgitation.

[A case of Aicardi syndrome: neurophysiological investigation]

A Japanese girl developed tonic spasms in series at two months after birth. When she was admitted at 4 months, she had generalized muscle hypotonia and could not control her head. She had atotal agenesis of the corpus callosum on MRI, reticulo-lacunitis revealed by ophthalmologic examination, and hypsarrhythmia in EEG. Brain stem auditory evoked potentials and flash-visual evoked potentials exhibited abnormally asymmetrical findings. The cortical components of somatosensory evoked potentials were not elicited on admission, but some components became to be recognized on median nerve stimulation in accordance with improvement of EEG findings after various therapeutic trials. We concluded that these neurophysiological examinations were useful to investigate the abnormal lesions of the central nervous system in patients with Aicardi syndrome.

Analysis of the heterogeneous transcripts of the highly edited orf206 in tomato mitochondria

RNA editing of tomato orf206, postulated to encode a subunit of the ABC-type heme transporter involved in the biogenesis of cytochrome c, was analyzed by sequencing products of RT-PCR. While half of the transcripts were fully edited, others were heterogeneous as a result of partial or unusual editing.

Mechanisms of satigrel (E5510), a new anti-platelet drug, in inhibiting human platelet aggregation. Selectivity and potency against prostaglandin H synthases isozyme activities and phosphodiesterase isoform activities

Satigrel (E5510, 4-cyano-5,5-bis(4-methoxyphenyl)-4-pentenoic acid) is a potent inhibitor of platelet aggregation. Like cyclooxygenase/prostaglandin H synthase (PGHS) inhibitors such as aspirin, which suppress platelet aggregation by inhibiting thromboxane A2 production, satigrel inhibits collagen- and arachidonic acid-induced aggregation of human platelets. In contrast to other PGHS inhibitors, satigrel, like cyclic nucleotide phosphodiesterase (PDE) inhibitors such as cilostazol, shows inhibitory activity against thrombin-induced platelet aggregation. To investigate the mechanism of the anti-platelet activity of satigrel, we examined the selectivity and potency of satigrel against PGHS isozyme activities and PDE isoform activities. Two isozymes of PGHS are known; constitutive enzyme (PGHS1) and inducible enzyme (PGHS2). Satigrel showed inhibitory activity against PGHS1 (IC50: 0.081 microM) and PGHS2 (IC50: 5.9 microM), suggesting the selective inhibition of PGHS1. Indomethacin, which is a selective inhibitor of PGHS1, showed similar selectivity against PGHS isozymes (IC50: 0.12 microM and 1.4 microM, respectively). These results support that satigrel suppresses thromboxane A2 production by inhibiting PGHS1. It is known that three isozymes of PDE exist in human platelets: Type V, which specifically hydrolyzes guanosine 3',5'-cyclic monophosphate (cGMP), Type III, which mainly hydrolyzes cAMP, and Type II, which hydrolyzes both cGMP and cAMP. We separated these three isozymes from human platelets and examined the inhibitory activity of satigrel against each enzyme. Of the three isozymes, the inhibitory activity of satigrel was the most potent against Type III PDE (IC50: 15.7 microM). The IC50 value for Type III corresponded with that for thrombin-induced platelet aggregation. Type V and Type II were also inhibited by satigrel (IC50: 39.8 and 62.4 microM, respectively). In human platelets, satigrel increased both cAMP and cGMP levels in a dose-dependent manner (100, 300 microM). In conclusion, satigrel inhibits collagen- and arachidonic acid-induced platelet aggregation through preventing thromboxane A2 synthesis by selective inhibition of the target enzyme, PGHS1, which exists in platelets. The anti-aggregating activity of satigrel against thrombin-induced aggregation may be due to elevation of the cyclic nucleotide levels through the inhibition of PDE isozymes.

Effects of LHRH, FSH and activin A on follistatin secretion from cultured rat anterior pituitary cells

We demonstrated the release of follistatin, an activin-binding protein, from cultured rat anterior pituitary cells by measuring immunoreactive (ir-) follistatin in a specific immunoradiometric assay. Ir-follistatin release gradually increased in cultures over 1-18 days and reached its maximal level at 12-15 days of incubation. The basal ir-follistatin levels in the culture media increased about 3- (P < 0.01) and 5-fold (P < 0.001) in 2 and 10% fetal calf serum for 6 days, respectively. LHRH and activin A caused an approximately 2.0- (P < 0.05) and 1.8-fold (P < 0.05) rise in ir-follistatin release, respectively, in contrast to the lack of significant FSH effects. The culture medium condensed on sulfate-cellulofine gel was resolved by polyacrylamide gel electrophoresis and blotted with anti-follistatin polyclonal antibody, resulting in at least three protein bands ranging from 35 to 50 kDa under non-reducing conditions. These results indicated that follistatin is produced in anterior pituitary cells and that its secretion is regulated at least in part by LHRH and activin, implying an autocrine/paracrine role of activin and follistatin in the pituitary.

Serum immunoreactive activin A levels in normal subjects and patients with various diseases

We developed and validated a RIA for measuring serum activin A. The least detectable value of this assay was 0.1 micrograms/L, and the antibody used cross-reacted slightly with bovine inhibin (3.2%) and porcine activin AB (10.0%) but not with porcine activin B (< 0.5%). Serum activin A was extracted with acetonitrile and trifluoroacetic acid to get rid of the interaction with possible binding proteins in serum. As a result of this extraction procedure, the dose-response curve of serum extract was parallel to the standard curve and a single immunoreactive (ir-) peak was demonstrated on gel chromatographic analysis with constant recovery rates over 80%. Serum ir-activin A level in healthy adults was 1.27 +/- 0.03 micrograms/L (mean +/- SEM, n = 180); being 1.38 +/- 0.05 micrograms/L (n = 90) in male, and 1.16 +/- 0.05 micrograms/L (n = 90) in female subjects, with a tendency to increase with age. Serum ir-activin A level during pregnancy showed a marked increase with the advance of gestation; 1.65 +/- 0.41 micrograms/L (n = 7) in the early, 4.50 +/- 1.13 micrograms/L (n = 21) in the middle, and 16.32 +/- 2.25 micrograms/L (n = 26) in the late trimester, with a rapid decline after delivery. On the other hand, serum ir-activin A level was elevated in patients with hyperthyroidism (1.91 +/- 0.37 micrograms/L, n = 31), liver cirrhosis (2.03 +/- 0.71 micrograms/L, n = 10), chronic renal failure (3.41 +/- 0.34 micrograms/L, n = 41), and advanced solid cancer (2.24 +/- 0.52 micrograms/L, n = 67). These findings indicate that serum ir-activin A level varies with physiological conditions such as aging and pregnancy, and that it may reflect the altered production and metabolism of activin A in certain diseased conditions.

Mass spectrometric screening method for microcystins in cyanobacteria

A screening method for microcystins in cyanobacteria, which consists of the formation of 3-methoxy-2-methyl-4-phenylbutyric acid as an oxidation product of microcystins by ozonolysis, and detection of 3-methoxy-2-methyl-4-phenylbutyric acid by thermospray-liquid chromatography/mass spectrometry or electron ionization-gas chromatography/mass spectrometry using selected ion monitoring, was developed. The ozonolysis made it possible to significantly reduce the formation times of 3-methoxy-2-methyl-4-phenylbutyric acid because the previously required extraction, clean-up and other procedures could be entirely eliminated. The resulting intact 2-methyl-4-phenylbutyric acid was directly analyzed by thermospray-liquid or electron ionization-gas chromatography/mass spectrometry, and the procedures from ozonolysis to analysis of microcystins at the pmole levels were performed within only 30 min. The calibration curves obtained by thermospray-liquid or electron ionization-gas chromatography/mass spectrometry analysis showed a linear relationship from 14 to 830 pmole and from 2.5 to 100 pmole of microcystin-LR, respectively. The method was applied to the detection and determination of the total amount of microcystins in bloom and cultured samples, showing that it provided a means of not only screening for microcystins but of their accurate quantitation.

Dissociation of P2 purinoceptor-mediated increase in intracellular Ca2+ level from myosin light chain phosphorylation and contraction in rat aorta

1. The effects of P2 agonists, adenosine-5'-triphosphate (ATP), alpha, beta-methylene-adenosine-5'-triphosphate (alpha, beta-me-ATP) and adenosine 5-O-(3-thiotriphosphate) (ATP gamma S), on the intracellular free Ca2+ level ([Ca2+]i), myosin light chain (MLC) phosphorylation and force of contraction were examined in vascular smooth muscle of rat aorta. 2. ATP (0.1 microM-1 mM), alpha, beta-me-ATP (0.1-100 microM) and ATP gamma S (1-100 microM) induced transient increases followed by sustained increase in [Ca2+]i. The effects of these agonists were concentration-dependent. Compared with the effects of a high concentration of KCl (17.5-72.4 mM), the contractions induced by these P2 purinoceptor agonists were smaller at a given [Ca2+]i. 3. In the absence of extracellular Ca2+ (with 0.5 mM EGTA), ATP gamma S (10 microM) induced large transient increase in [Ca2+]i with only small contraction in Ca(2+)-free solution. In contrast, alpha, beta-me-ATP (10 microM) induced only a very small increase in [Ca2+]i and contraction. 4. ATP (1 mM), alpha, beta-me-ATP (10 microM) and ATP gamma S (10 microM), added during stimulation with 0.1 microM noradrenaline, induced additional and transient increases in [Ca2+]i which were also not associated with contraction. 5. High K+ (72.4 mM) increased MLC phosphorylation with a similar time course to that of the increase in [Ca2+]i (peak phosphorylation was 56% when [Ca2+]i increased to 100%). In contrast, the time course of the increase in MLC phosphorylation due to ATP (1 mM) did not coincide with that of the large increases in [Ca2+]i; MLC phosphorylation increased to only 31% when [Ca2+]i increased to 163%. The MLC phosphorylation due to alpha, beta-me-ATP (10 microM) and ATP gamma S (10 microM), measured at peak [Ca2+]i, were only 19% and 14%, respectively, irrespective of a large increase in [Ca2+]i (138% and 188%, respectively). 6. The absence of a clear relationship between P2-purinoceptor-mediated increase in [Ca2+]i (either by Ca2+ influx or Ca2+ release) and MLC phosphorylation or force generation appears to imply that elevation in [Ca2+]i does not contribute to these responses.

Analysis of suppressor mutations of spoIVCA mutations: occurrence of DNA rearrangement in the absence of site-specific DNA recombinase SpoIVCA in Bacillus subtilis

The spoIVCA gene of Bacillus subtilis encodes a site-specific recombinase, which excises a 48-kb skin element from the chromosomal DNA by DNA rearrangement and creates a new composite gene, sigK, on the chromosome. From spoIVCA mutants, we have isolated Spo+ revertants which have no skin element but have an intact sigK gene. This result suggests that the DNA rearrangement can occur in the absence of spoIVCA.

Clinical investigation of 145 cases of chronic lymphocytic leukemia in Japan

CLL is the most common leukemia in Europe and America, representing 30% of all forms of leukemia. In contrast, in Japan, the incidence is only 3%. This is the largest multicenter study in Japan to evaluate the relationship between outcome in CLL patients and the data obtained during patient's first visits. The data obtained during first visits of 145 patients with chronic lymphocytic leukemia (CLL) that were made between 1982 and 1991 and their outcomes were analyzed and compared with those of patients with CLL diagnosed in terms of Rai and Binet staging in Europe and America. In our patients, the male-to-female ratio was 1.8, and the mean age at onset was 63.2+/-11.7 (+/-SD) years. The crude 5-year survival rate was 42.4% in men and 44.9% in women. Patients with B-CLL with surface IgM phenotype had better outcomes than those with B-CLL with surface IgG (P<0.1); patients with surface IgM/IgD phenotypes and those with T-CLL had the poorest outcomes (B-CLL with surface IgM vs. B-CLL with surface IgM/IgD T-CLL, P<0.05). When these patients were re-evaluated in terms of Binet and Rai staging, generalized Wilcoxon analysis revealed no differences between the survival curves of different stage groups, as seen in patients with CLL in Europe and America. Patients whose CLL developed during their fifties or earlier had the most favorable outcomes (P<0.05); the later the onset of disease, the worse the outcome. CLL was associated with hypogammaglobulinemia (30%) and autoimmune hemolytic anemia (7.6%), and 4 patients (2.8%) died of secondary cancer. Outcomes of our patients were compared with those of patients with CLL in Europe and America.

Clinical pharmacology of multiple-dose losartan, an angiotensin II receptor antagonist, in patients with essential hypertension

The pharmacokinetic and pharmacodynamic alterations of multiple doses of losartan, an angiotensin II receptor antagonist, were examined in nine patients with essential hypertension. Participants were given placebo once daily for the first 7 days (from day -7 to day -1), and then 50 mg of losartan for the next 9 days (from day 1 to day 9). The 24-hour blood pressure was measured on days -1, 1, and 7 and blood samples for measurement of losartan and its active metabolite, E-3174, were obtained on days 1 and 7. Plasma concentrations of uric acid and plasma clearance were determined before and during treatment with losartan, and at the end of the study. Pharmacokinetic parameters after the seventh dose, including maximum plasma concentration (Cmax) and time to Cmax (tmax) of losartan and E-3174, did not differ significantly from those after the first dose. The blood pressure lowering effect of losartan, however, was significantly greater after the seventh dose than after the first dose. Plasma uric acid decreased and its plasma clearance (ClUA) increased significantly during repeated administration with losartan. These values returned to pretreatment levels after the end of treatment. These results suggest that although the pharmacokinetic profiles of losartan and E-3174 do not change during repeated administration, the blood pressure lowering effect in hypertensive patients is greater after multiple doses than after a single dose.

Transcription factor PU.1 mediates induction of c-fms in vascular smooth muscle cells: a mechanism for phenotypic change to phagocytic cells

The macrophage colony-stimulating factor receptor encoded by the c-fms gene is expressed in vascular intimal smooth muscle cells isolated from atherosclerotic lesions. A combination of platelet-derived growth factor-BB and epidermal growth factor induces stable expression of c-fms in normal vascular medial smooth muscle cells. The mechanism by which these growth factors induce c-fms expression has now been investigated in an attempt to gain insight into the events that underlie the phenotypic conversion of vascular smooth muscle cells in atherosclerosis. Deletion analysis of the c-fms promoter revealed that the region including a binding site for transcription factor PU.1 was required for transcriptional activity in human aortic medial smooth muscle cells. Mutation in the PU.1 binding site markedly reduced promoter activity. Northern (RNA) blot analysis demonstrated that growth factors induced the expression of PU.1 mRNA in vascular medial smooth muscle cells and that PU.1 mRNA was expressed in vascular intimal smooth muscle cells. PU.1 antisense oligonucleotides inhibited growth factor-induced c-fms expression and foam cell formation. These results suggest that transcription factor PU.1 plays an essential role in the phenotypic conversion of vascular smooth muscle cells to macrophagelike cells by mediating the induction of c-fms.

Vascular endothelial growth factor administration in chronic myocardial ischemia

Vascular endothelial growth factor (VEGF) is a potent mitogen capable of stimulating angiogenesis. We examined the effect of VEGF administration in a model of chronic porcine myocardial ischemia. Nineteen pigs were instrumented with proximal left circumflex coronary artery (LCX) Ameroid constrictors. In eight animals VEGF (2 microgram) with heparin (50 U) was administered extraluminally to the LCX myocardium with an osmotic pump for 4 wk and 11 other animals served as controls. VEGF-treated animals demonstrated higher flow in the LCX territory during both rest and pacing compared with untreated controls (rest: 1.35 +/- 0.1 vs. 0.80 +/- 0.09 ml.min-1.g-1; pacing; 2.01 +/- 0.37 vs. 1.01 +/- 0.07 ml.min-1.g-1, P < 0.05, VEGF vs. controls). The observed improvement in regional coronary flow in VEGF-treated animals resulted in better preservation of endothelium-dependent microvessel relaxation as well as fractional LV shortening in the LCX territory during pacing in the VEGF-treated than in control animals (controls: 7.1 +/ 2.6 vs. 3.6 +/- 2.0%, rest vs. pacing; VEGF: 6.9 +/- 2.9 vs. 6.3 +/- 2.9%, rest vs. pacing). We conclude that VEGF administration in a gradual coronary occlusion model in pigs results in improvement of coronary flow and preservation of regional hemodynamics in the compromised myocardium.

Effect of renin-angiotensin inhibition on glomerular injuries in DOCA-salt hypertensive rats

To determine whether growth factors in the glomerulus are induced in the renin suppressed hypertensive model, we examined the mRNA expressions of platelet-derived growth factor (PDGF) B-chain, transforming growth factor (TGF)-beta 1 and angiotensin II type 1 (AT1) receptors in the glomeruli of deoxycorticosterone acetate (DOCA)-salt-treated hypertensive rats (DOCA-treated rats). We also examined the effects of treatment with cilazapril, an angiotensin I-converting enzyme inhibitor (ACEI), and L-158,809, an AT1 receptor antagonist, on these expressions in DOCA-treated rats. We administered oral 10 mg/kg of cilazapril (CILAZA group) and 1 mg/kg of L-158,809 (L158 group) to DOCA-treated rats daily. Systolic blood pressure in the two groups was not decreased compared with that in DOCA-treated rats given saline. The mRNA expressions were examined using reverse transcriptase polymerase chain reaction (RT-PCR) methods. The mRNA expressions of these genes were higher in DOCA-treated rats than in age-matched control rats. After treatment with these agents for 4 weeks, the mRNA expressions of growth factors were suppressed in both the CILAZA and L158 groups. Mesangial expansion and cell proliferation observed in DOCA-treated rats were suppressed in both the CILAZA and L158 groups. Decreases in the size of the glomerulus were observed only in the CILAZA group. These findings suggested that suppression of growth factors and glomerular proliferative changes of these agents are mediated by blocking tissue renin-angiotensin system (RAS) in the renin-suppressed model.

Influence of age on venodilator effect of isoproterenol and amrinone

OBJECTIVE

To investigate the influence of age on the venodilator effect of isoproterenol, a beta-adrenoceptor agonist, and amrinone, a selective phosphodiesterase (PDE) III inhibitor, in human subjects.

METHODS

In eight young and eight elderly male subjects, the drugs were infused into a dorsal hand vein preconstricted with phenylephrine and its diameter was measured using a linear variable differential transformer.

RESULTS

The maximum venodilation (Emax) induced by isoproterenol was significantly smaller and the infusion rate of isoproterenol required to induce 50% of maximum venodilation (ED50) was significantly larger in the elderly than in the young subjects [Emax: 29.8 vs 95.1%, ED50: 97.3 vs 51.6 ng.min-1]. A significant age-related change in Emax or ED50 was not observed for amrinone (Emax: 95.8 vs 100.8%, ED50: 40.1 vs 31.6 micrograms.min-1).

CONCLUSION

The data show that the venodilator effect of amrinone is not influenced by age. As amrinone increases cyclic AMP by inhibition of PDE III, it is suggested that the action of cyclic AMP is not altered by age. The decreased effect of isoproterenol might be caused by reduced production of cyclic AMP in elderly subjects.

Mesenchymal chondrosarcoma in anterior skull base: case report

We report the case of a 16-year-old boy who presented with mesenchymal chondrosarcoma involving the ethmoid sinus, right orbit, nasal cavity, and anterior cranial fossa. The tumor was totally resected by craniofacial surgery; the patient's postoperative course was uneventful. Microscopically, the tumor was composed of highly cellular undifferentiated small cells, alternating with zones of cartilaginous tissues. Mesenchymal chondrosarcoma is a rare, aggressive variant of chondrosarcoma, which might be encountered more frequently due to the advances in neuroimaging and surgical procedures.