Chemical modification of erythromycins. VI. Structure and antibacterial activity of acid degradation products of 6-O-methylerythromycins A.
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Bacteria↗
Biomedical subjects
S Morimoto
Publications and source records attributed to S Morimoto.
Effects of BRL 34915 (cromakalim) on renal hemodynamics and function in anesthetized dogs.
The effects of BRL 34915, a newly developed potassium channel opener, on renal hemodynamics and function were investigated in anesthetized dogs. An i.v. injection of BRL 34915 (4, 20 and 100 micrograms/kg) caused a dose-related reduction of mean arterial pressure but there were no significant changes in renal blood flow. The agent at lower doses (4 and 20 micrograms/kg) produced a slight increasing action on urine formation. When BRL 34915 was infused intrarenally at nonhypotensive doses (0.04 and 0.2 micrograms/kg/min), there were no significant increases in renal blood flow and glomerular filtration rate. At 1.0 micrograms/kg/min, a dose which produced a slight reduction in mean arterial pressure, significant decreases in calculated renal vascular resistance were observed, thereby indicating that BRL 34915 has vasodilator action on the renal vasculature. In cases of infusion at higher doses (0.2 and 1.0 micrograms/kg/min), the levels of urine flow, urinary excretion of sodium and fractional excretion of sodium were elevated significantly and these events were accompanied by decreases in urine osmolality. Although the intrarenal administration of BRL 34915 at higher doses produced no alterations in the fractional excretion of lithium (index of sodium excretion at the proximal tubules), the agent did increase the calculated value of the fractional distal excretion of sodium. These effects seen when BRL 34915 was infused intrarenally were suppressed markedly by glibenclamide (6 mg/kg i.v.), a putative inhibitor of the ATP-sensitive potassium channel. Our results suggest that BRL 34915 has renal vasodilating and diuretic effects as a result of opening the potassium channels within the kidney. The agent-induced diuresis may be due partly to an inhibitory effect on sodium reabsorption at the distal portion of the tubules beyond the proximal tubules.
Animals↗
A case of malignant histiocytosis successfully treated with combination interferon and etoposide therapy.
A 66-year-old woman with malignant histiocytosis was treated with a combination of recombinant gamma interferon (GI-3) and etoposide. Following partial response to intravenous gamma interferon (9 x 10(6) units (U)/day) alone, the patient received an eight-months course of subcutaneous gamma interferon (0.5 x 10(6) U/day) and intravenous etoposide (100 mg/week). After two years, the patient remains in complete remission. The present case report discusses the successful use of combination gamma interferon and etoposide for the treatment of malignant histiocytosis.
Aged↗
[Two autopsied cases of arrhythmogenic right ventricular dysplasia].
Autopsy studies of arrhythmogenic right ventricular dysplasia (ARVD) have rarely been reported, and its etiology remains unknown. The present report describes a detailed histopathological study of two autopsied cases of ARVD. Case 1: This 21-year-old man experienced palpitation accompanied by syncope. He died after ventricular tachycardia of right ventricular origin. The heart weighed 365 g and the right ventricular cavity was markedly dilated. The distribution of fatty tissue was roughly limited to the middle layer of the free wall, replacing the myocardium with fatty degeneration. Medial hyperplasia of the small arteries within the fatty tissue was also observed. Fibroelastosis was observed in the left ventricular endocardium. In the conduction system, fatty tissue was found in the sinus node. In addition, medial hypoplasia was observed in the pulmonary arteries. Case 2: This 32-year-old man who had had an arrhythmia for 10 years died of ventricular tachycardia of right ventricular origin. His older brother also died of heart disease. His heart weighed 515 g and both the right and left ventricles were dilated. Fatty tissue, unlike that in Case 1, was shown to markedly infiltrate from the epicardium into both the right and left ventricular walls. In the right ventricular wall, muscle layers disappeared in some portions. In the conduction system, fatty tissue was observed in the sinus node. Although ARVD may be considered a syndromic entity, individual cases are different in terms of pathological morphology, with possible variations in the etiology and pathogenesis.
Adipose Tissue↗
[A new macrolide antibiotic, clarithromycin--synthesis, structure-activity relationship and metabolism].
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Animals↗
Nicorandil is a potent dilator of endothelin-induced vascular contraction.
Nicorandil, an antianginal drug, is known to open K+ channel and to increase cGMP production. The effects of nicorandil on vascular contraction induced by endothelin (ET), a potent newly discovered vasoconstrictor peptide, were investigated using helical strips from rat thoracic aorta. ET at a concentration of 5 x 10(-9) M induced strong and persistent contraction in the presence of extracellular Ca2+ and similar persistent but smaller contraction in the absence of extracellular Ca2+. Nicorandil at concentrations greater than 10(-7) M, strongly and dose-dependently inhibited ET-induced contraction in the presence of extracellular Ca2+. Nicorandil also suppressed ET-induced contraction in the presence of 10(-4) M methylene blue, an inhibitor of cGMP production, in the presence of extracellular Ca2+ but not in the absence of extracellular Ca2+. ET-induced contraction was also inhibited to lesser extents by the Ca2+ channel blockers nicardipine and verapamil. Nicorandil also strongly suppressed ET-induced increase in cytosolic free Ca2+ concentration in cultured vascular smooth muscle cells. These results suggest that nicorandil is a potent dilator of ET-induced vasoconstriction.
Animals↗
Stimulatory effect of 1,25-dihydroxyvitamin D3 on transferrin synthesis in primary cultures of adult rat hepatocytes.
The effect of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] on protein synthesis was studied in primary cultures of adult rat hepatocytes, in comparison with those of dexamethasone (DEX). The transferrin (TF) level in the culture medium assayed by a radioimmunoassay (RIA), after incubation for 24 hr was increased in the presence of 1,25-(OH)2D3, significantly at concentrations of more than 10(-12) M and maximally to about 140% of that in control cultures at 10(-8) M, without change in the albumin concentrations, assayed by an EIA. Other vitamin D3 metabolites had similar but weaker effects in increasing transferrin synthesis. On the other hand, incubation with 10(-6) M Dex for 24 hr enhanced the syntheses of both transferrin and albumin. Addition of 10(-7) M actinomycin D did not significantly block the effect of 1,25-(OH)2D3, but did suppress that of dexamethasone. These results indicate that 1,25-(OH)2D3 stimulates TF synthesis of cultured rat hepatocytes with different mechanism(s) of action from that of dexamethasone.
Albumins↗
Endothelin stimulates Na+/H+ exchange in vascular smooth muscle cells.
The effect of endothelin (ET) on the intracellular pH (pHi) of vascular smooth muscle cells (VSMC), was investigated using a fluorescent pH indicator 2',7'-bis(carboxyethyl)carboxyfluorescein (BCECF). ET at concentrations of over 10(-9) M caused dose-dependent transient acidification followed by Na(+)-dependent and amiloride-sensitive alkalization of the cells due to stimulation of Na+/H+ exchange. The alkalization induced by ET was Ca2(+)-dependent and was inhibited by a calcium channel blocker, nicardipine. Pretreatment with H-7, an inhibitor of protein kinase C, also inhibited the ET-induced cell alkalization. These results indicate that ET stimulates Na+/H+ exchange, resulting in alkalization of VSMC and that this ET-induced cell-alkalization is probably linked to Ca2+ influx and activation of protein kinase C.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
[Three cases of esophageal or upper gastric varices due to invasion of malignant tumor to the portal vein].
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Aged↗
Conversion of rat urinary prokallikrein to its active form.
A peptide derived from rat urinary prokallikrein by trypsin treatment comprised 7 amino acids, the sequence (Ala-Pro-Pro-Val-Gln-Ser-Arg) of which was identical with that of the N-terminal region in prokallikrein. Thus, with trypsin treatment, rat urinary prokallikrein is converted to the active form with the release of the N-terminal propeptide consisting of 7 amino acids. An Arg-1-Val+1 bond in the prokallikrein was found to be the site of proteolytic cleavage of the propeptide.
Amino Acid Sequence↗
Acute radiation-induced pulmonary injury: computed tomography evaluation.
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Acute Disease↗
The action of low density lipoprotein on vascular smooth muscle cells involves increase in intracellular pH.
The effect of low density lipoprotein (LDL) on the intracellular pH (pHi) of vascular smooth muscle cells (VSMC) was investigated using a fluorescent pH indicator, 2',7'-bis(carboxyethyl)carboxyfluorescein (BCECF). LDL and apoprotein B (apo-B), a binding protein for the LDL receptor, caused transient acidification followed by Na(+)-dependent and amiloride-sensitive alkalization of the cells due to stimulation of Na+/H+ exchanger. NH4Cl also caused intracellular alkalization, but independently of extracellular Na+. LDL, apo-B and NH4Cl all stimulated thymidine incorporation. These results indicate that the binding of LDL to its receptor stimulates Na+/H+ exchanger, resulting in alkalization of VSMC and suggest that this may function as a massage in stimulation of DNA synthesis evoked by LDL.
Amiloride↗
Histopathological assessment of endomyocardial biopsy in children: I. Semiquantitative study on the hypertrophy of cardiac myocytes.
Over 200 endomyocardial biopsies in pediatric patients have been performed since 1962, and an appropriate interpretation of myocardial hypertrophy in biopsy specimens at different ages is now necessary. The diameter of myocytes was measured in 108 biopsy specimens and 209 autopsy specimens from pediatric cases. There was a gradual increase in the myocyte diameter according to age in the biopsy and autopsy specimens. The diameter became adult size at 13 to 15 years of age in the right ventricle and at 9 to 15 years in the left ventricle. The myocyte size of diseased hearts was greater than that of normal hearts at each age. The coefficient of variance of the mean myocyte diameter in heart muscle disease, including hypertrophic cardiomyopathy and dilated cardiomyopathy, was greater than in other hearts. These results suggested that it is possible to ascertain myocardial hypertrophy by measuring the diameter of cardiac myocytes. A proposed grading system of the degree of myocyte hypertrophy for the biopsy specimens at various pediatric ages is reported.
Adolescent↗
Interleukin-6 stimulates c-myc expression and proliferation of cultured vascular smooth muscle cells.
The effects of interleukin-6 (IL-6), a cytokine recently found to be secreted by monocytes and macrophages, on c-myc expression and proliferation of cultured vascular smooth muscle cells (VSMC) were investigated. Treatment with IL-6 caused rapid increase in the c-myc mRNA level of VSMC. It also stimulated DNA synthesis and proliferation of the cells significantly and dose-dependently at concentrations of more than 10 U/ml. These results suggest that IL-6 may be important in the proliferation of VSMC, which is a key event in the development of arteriosclerosis, as a factor mediating immune cell-VSMC interaction.
Animals↗
[A case of myonephropathic-metabolic syndrome after urgent aortic valve re-replacement due to prosthetic valve thrombosis].
Acute cardiac failure due to prosthetic valve thrombosis is a rare, but lethal complication after cardiac valve replacement. A 40-year-old female admitted to our hospital, because of cardiac failure after aortic valve replacement with a #21 Björk-Shiley valve in 1975. After admission, echocardiography showed thrombotic obstruction of the prosthetic valve, and we underwent urgent aortic valve re-replacement. Postoperative period, she was complicated with myonephropathic-metabolic syndrome (MNMS). But, we performed intermittent veno-venous hemofiltration (IVVH) in early period, and successfully could save her life and her lower limb.
Adult↗
[Primary plasmacytoma of the thyroid--report of an autopsy case and review of the literature in Japan].
Primary extramedullary plasmacytoma (PEMP) of the thyroid is rare. Only nine patients with PEMP of the thyroid have been reported in Japan to date. We describe an additional autopsy case with PEMP of the thyroid and review of the literature in Japan. A 67-year-old women complaining of swelling of the anterior neck exhibited thin scalp hair, edematous face and a giant, hard, nodular goiter. Laboratory examination showed elevated levels of ESR, collagenous reaction, gammaglobulin, and a M-bow of the IgG-k type in immunoelectrophoresis. No Bence-Jones protein was found in the urine. Thyroid function test revealed a subclinically hypothyroid state, showing a T3 of 1.32 ng/ml, a T4 of 10.0 micrograms/dl, a TSH of 23.4 microU/ml and positive thyroid antibodies. The scintigram and the CT scan of the thyroid showed deviation of the trachea by the thyroid tumor and calcification within homogeneous thyroid gland. She underwent total thyroidectomy because of suspected malignancy. The histological examination of the removed thyroid weighing 117gr revealed a proliferation of plasma cells and lymphocytes and small amounts of atrophied thyroid follicles. The immunohistological examination of the removed thyroid showed the monoclonality to IgG-k chain. Plasma cells were stainable with methylgreenpyronine. Twenty-six months after thyroidectomy, she died due to progressive emaciation, anemia, hypoalbuminemia and ascites. Postmortem examination revealed widespread metastasized plasma cell tumors in the liver, intestine, spleen and mesentery with ischemic changes in heart and kidney. Based on our autopsy case and the nine cases reported in Japan, clinical and histological characteristics of PEMP of the thyroid were discussed.
Aged↗
Comparison of effects of a potassium channel opener BRL34915, a specific potassium ionophore valinomycin and calcium channel blockers on endothelin-induced vascular contraction.
The effects of a potassium (K+) channel opener BRL34915 and a specific K+ ionophore valinomycin on vasoconstriction induced by endothelin (ET) were compared with those of calcium (Ca2+) channel blockers, nicardipine and verapamil, using helical strips from rat thoracic aorta. ET induced potent and persistent contraction in control solution and similar but smaller contraction in Ca2+-free solution. BRL34915 and valinomycin inhibited the ET-induced contraction dose-dependently in control solution, but not in Ca2+-free solution. The ET-induced contraction was also inhibited by nicardipine and verapamil, though less strongly. On the other hand, high K+ (35 mM)-induced vasoconstriction was strongly inhibited by nicardipine and verapamil, but not by BRL34915 or valinomycin. These results support the idea that the extracellular Ca2+-dependent component of the ET-induced contraction may be mediated by Ca2+ influx by a route other than voltage-dependent Ca2+-channels.
Animals↗