Yoshiharu Kanayama

Immunopathologic Studies of Pneumonitis in Systemic Lupus Erythematosus

We performed immunohistopathologic studies on biopsied lung tissue obtained from two patients with lupus pneumonitis using immunofluorescence, immunoperoxidase, electron microscopy, and acid-microelution. In both patients, immunofluorescence showed granular deposits of IgG, the third component of complement (C3), and DNA in the alveolar walls. The immunoperoxidase technique in both and electron microscopy in one showed that these deposits were in the interstitium of the alveolar walls and in the alveolar capillary walls. The eluates obtained from cryostat sections of the biopsied lungs contained antinuclear factor of IgG class in one patient and showed anti-DNA antibody activity in both. We suggest that the deposits are immune complexes composed of DNA, anti-DNA antibody, and complement and that deposits of DNA-anti-DNA immune complex may play a role in lupus pneumonitis.

Atrial natriuretic polypeptide in atria and plasma in experimental hyperthyroidism and hypothyroidism.

To investigate the involvement of thyroid hormone on the release of atrial natriuretic polypeptide (ANP), we have measured immunoreactive ANP in the atria and plasma of experimental hyperthyroid and hypothyroid rats. Plasma ANP was higher (p less than 0.05) in hyperthyroid rats and was lower (p less than 0.05) in hypothyroid rats than in euthyroid rats. ANP content and concentration in the atria were lower (p less than 0.01) in hyperthyroid rats than in hypothyroid rats. An inverse correlation was found between the plasma ANP and ANP concentration in the atria (n = 15, r = 0.60, p less than 0.01). The results indicate an increased systemic release of ANP from the atria in hyperthyroidism and a decreased systemic release in hypothyroidism.

Lovastatin inhibits gene expression of type-I scavenger receptor in THP-1 human macrophages.

Lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, inhibits the synthesis of mevalonic acid and is widely used as an anti-atherosclerotic drug. The macrophage scavenger receptor (SCR), a trimeric membrane glycoprotein, is postulated to play a key role in atheroma macrophage foam cell formation. HMG-CoA reductase is involved in the control of the synthesis of glycoproteins and farnesylated proteins, including ras proteins, which are involved in the transcriptional regulation of SCR gene expression. Accordingly, we examined whether lovastatin alters the gene expression of SCRs in THP-1 cell derived human macrophages. Lovastatin (5-15 microM) caused a significant dose-related reduction in steady state levels of type-I SCR mRNA in phorbol 12-myristate 13-acetate (PMA)-treated THP-1 cells. The addition of exogenous mevalonate (1 mM) completely restored the lovastatin-induced decrease of type-I SCR mRNA levels. While the addition of the isoprenoid end-product, isopentenyl adenine (50 microM), had little effect on the type-I SCR mRNA levels in lovastatin treated cells, the addition of isoprenoid farnesol (5 microM) largely restored the lovastatin-induced decrease of type-I SCR mRNA levels. Actinomycin D treatment showed that degradation rates of type-I SCR mRNA did not differ between the THP-1 derived cells with and without lovastatin treatment. Nuclear run-on assays showed that lovastatin markedly decreased the transcription of SCR gene in the cells. These results suggest that lovastatin inhibits the transcription of type-I SCR gene by affecting mevalonate metabolism, possibly through the farnesyl-pyrophosphate related end-product(s) in the THP-1-derived macrophages.

Protein kinase c activity in platelets from spontaneously hypertensive rats (SHR) and normopensive wistar Kyoto rats (WKY)

Calcium-activated phospholipid dependent protein kinase (protein kinase C) activity in platelets was measured in 4, 12, and 20-week-old SHR and WKY. At age 4-weeks, there was no significant difference in protein kinase C activity and systolic blood pressure between SHR and WKY. In 12 and 20-week-old SHR, both protein kinase C activity and systolic blood pressure were significantly higher than in the age-matched WKY. These results suggest that protein kinase C may be involved in the control of blood pressure in SHR and WKY.

Thrombin stimulates the production of immunoreactive endothelin-1 in cultured human umbilical vein endothelial cells.

The present study was designed to examine the effect of thrombin on endothelin production by cultured human umbilical vein endothelial cells (HUVEC) by radioimmunoassay. Cultured HUVEC released immunoreactive endothelin-1 (ir-endothelin-1) into the medium in a time-dependent manner. This release was inhibited completely by 10 micrograms/mL cycloheximide and is, therefore, directly related to de novo protein synthesis. Further endothelin release was stimulated by the addition of thrombin to the culture medium. Thrombin-induced ir-endothelin-1 release also was inhibited completely by 10 micrograms/mL cycloheximide. These results suggest that HUVEC in culture produce ir-endothelin-1 slowly, but continuously, and that this production is stimulated by thrombin.

Decreased intracellular free magnesium in erythrocytes of spontaneously hypertensive rats

Using 31p-NMR (the phosphorus nuclear magnetic resonance) spectroscopy, we measured intracellular free Mg levels in the erythrocytes of untreated (n = 7) and diltiazem-treated spontaneously hypertensive rats (SHR) (n = 8), and compared them with age-matched Wistar-Kyoto rats (WKY) (n = 10). The intracellular free Mg levels were significantly (p less than 0.01) decreased in untreated SHR compared with those in control WKY. A successful antihypertensive treatment with diltiazem increased the intracellular free Mg levels compared with untreated SHR (p less than 0.05). Furthermore, an inverse correlation was observed between intracellular free Mg levels and blood pressure levels in all groups (r = -0.48, p less than 0.01, n = 25). These observations suggest that abnormalities of intracellular Mg metabolism may be, in part, related to the development or the maintenance of hypertension in SHR.

Effects of high-sodium and low-sodium intake on circulating atrial natriuretic peptides in salt-sensitive patients with systemic hypertension

Abstract Recently, we showed that the levels of circulating atrial natriuretic peptides (ANP) in adult spontaneously hypertensive rats are higher than those in Wistar-Kyoto rats, and that high salt intake causes an accelerated increase of circulating ANP in spontaneously hypertensive rats. 1 The present study was designed to elucidate the role of ANP in salt sensitivity in patients with essential hypertension.

cAMP-induced changes of intracellular free Mg2+ levels in human erythrocytes.

To examine the role of cAMP in the regulation of intracellular free magnesium concentration ([Mg2+]i), we measured [Mg2+]i in human erythrocytes by 31P-NMR spectroscopy. (-)-Isoproterenol, forskolin, Bt2cAMP and 8-bromo-cAMP decreased [Mg2+]i in human erythrocytes. Bt2cAMP did not increase the efflux rate of Mg2+ from erythrocytes. HA1004, a potent inhibitor of cAMP-dependent kinases, markedly increased the [Mg2+]i in a Mg(2+)-free buffer solution. Addition of 8-bromo-cGMP or 12-O-tetradecanoylphorbol 13-acetate (TPA) did not affect the [Mg2+]i. These results suggest that beta-adrenergic stimulation and cAMP play an important role in the regulation of [Mg2+]i in human erythrocytes.

Differential diagnosis of fever in systemic lupus erythematosus using discriminant analysis

SummaryIn an attempt to find a reliable method to assess fever in patients with systemic lupus erythematosus (SLE), a multifactorial analysis was applied to the routine laboratory examinations, including white blood cell count (WBC) and serum globulin fraction concentrations. During 74 febrile episodes, 49 SLE patients showed increased disease activity and the remaining 25 febrile episodes were due to intercurrent infection. The two different groups of fever episodes were clearly separated by a principal component analysis using five variables from the routine laboratory tests, including WBC, serum alpha-1, alpha-2, beta, and gamma globulins. Discriminant analysis showed that 95% of 74 febrile episodes could be correctly classified as to the cause of fever when a combination of WBC and alpha-2 globulin level was used as variables. A simple discriminant formula which we calculated was considered to be of practical use for the differentiation of the two clinical entities.

Angiotensin-Converting Enzyme in the Rat Kidney

While it is known that angiotensin-converting enzyme (ACE) in the kidney is concentrated at the brush borders of the proximal tubule, the role of tubular ACE in renal physiology is not well understood. The active site of tubular ACE is exposed on the luminal surface of the brush borders and may hydrolyze peptides in the glomerular filtrate. However, a positive correlation between blood pressure and renal ACE activity was observed in spontaneously hypertensive rats, as well as in cases of ACE inhibition. Determination of ACE activity in different renal zones and immunohistochemistry demonstrated that ACE predominates in the inner cortex and that the proximal tubule in the outer cortex contains less ACE. Perhaps the inner cortex is the area responsible for alteration of renal ACE activity, since only ACE activity in the inner cortex increased following administration of the ACE inhibitor captopril. This would suggest that the induction of ACE occurs in the inner cortex. Renal ACE activity is also affected by oxidation. Thus, the activity increased when diamide, an oxidizing agent, was added to the crude extract of renal cortex and when oxygen was introduced into the extract. Therefore, tissue oxidation may be one factor affecting renal ACE activity.