Azidobutyryl clentiazem, a new photoactivatable diltiazem analog, labels benzothiazepine binding sites in the alpha 1 subunit of the skeletal muscle calcium channel

[3H]Azidobutyryl clentiazem, a new photoactivable diltiazem derivative, has a higher binding affinity than azidobutyryl diltiazem. It can be covalently incorporated into the alpha 1 subunit of the skeletal muscle calcium channel by UV irradiation, which allows the benzothiazepine binding site to be determined. The photolabeled alpha 1 subunit and its proteolytic fragments were analyzed with a panel of sequence-directed antibodies. The results suggest that the linker region between segment S5 and S6 of domain IV is involved in benzothiazepine binding. This site is different from the dihydropyridine and verapamil binding sites.

Inflammatory polyarthritis in mice transgenic for human T cell leukemia virus type I

OBJECTIVE

We have recently reported that arthropathy develops in high incidence among transgenic mice carrying the pX region of human T cell leukemia virus type I (HTLV-I). In the present study, the histopathologic features of the joints in these mice were examined in order to compare the animal disease with rheumatoid arthritis (RA) in humans.

METHODS

Paraffin sections of limbs (right and left fingers, wrists, elbows, shoulders, toes, knees, and ankles) were stained with hematoxylin and eosin, periodic acid-Schiff, azan-Mallory, or phosphotungstic acid hematoxylin, and examined by light microscopy.

RESULTS

Abnormalities of the limbs began to occur as early as 3 weeks of age, and the incidence gradually increased until the mice were 12 months old. The incidence of arthropathy was 22% (48 of 217) at 3 months of age and 28% (18 of 64) at 6 months. The severity of the histopathologic changes in the joints of the transgenic mice ranged from grade I to grade IV.

CONCLUSION

The major histopathologic features in the joints of HTLV-I transgenic mice are similar to those in humans with RA. Thus, these mice may represent a useful model for the study of the disease in humans.

Identification of 1,4-dihydropyridine binding domains within the primary structure of the alpha 1 subunit of the skeletal muscle L-type calcium channel

Calcium channel blockers are drugs that bind to the alpha 1 subunit of L-type calcium channels and selectively inhibit ion movements through these channels. Determination of the mechanism of channel blockade requires localization of drug-binding sites within the primary structure of the receptor. In this study the 1,4-dihydropyridine-binding site of the membrane bound receptor has been identified. The covalently labeled receptor was purified and digested with trypsin. The labeled peptide fragments were immunoprecipitated with sequence-directed antibodies. The data indicate the existence of at least three distinct dihydropyridine-binding domains within the primary structure of the alpha 1 subunit.

Evidence for the existence of RNA of Ca(2+)-channel alpha 2/delta subunit in Xenopus oocytes

Ba(2+)-currents (IBa) through voltage-dependent Ca(2+)-channels were studied in Xenopus oocytes injected with RNA from several excitable tissues, using the two-electrode voltage-clamp technique. Previous studies have shown that the expression of cardiac Ca(2+)-channels can be suppressed by an hybrid-arrest procedure that includes co-injection of the tissue-derived RNA with an 'antisense' oligonucleotide complementary to a part of RNA coding for the Ca(2+)-channel alpha 1 subunit. In this study, this method was used to investigate the role of the alpha 2/delta subunit. Co-injection of RNA extracted from either rabbit heart, rat brain or rat skeletal muscle (SkM) with 'antisense' oligonucleotides complementary to the alpha 2/delta subunit RNA did not substantially affect the expression of IBa in the oocytes. Using the Northern blot hybridization method, it was shown that native oocytes contain large amounts of alpha 2/delta subunit RNA of Ca(2+)-channel. It is proposed that te oligonucleotide treatment fails to eliminate the alpha 2/delta RNA because of the vast excess of endogenous alpha 2/delta RNA. These results impose a limit on the use of the hybrid-arrest method.

Beta-subunit expression is required for cAMP-dependent increase of cloned cardiac and vascular calcium channel currents

In contrast to vascular smooth muscle (VSM), cAMP-dependent phosphorylation increases L-type voltage dependent Ca(2+)-channel (L-VDCC) activity in heart. To investigate whether this difference depends on the tissue-specific alpha 1-subunit of the L-VDCC or its regulation by other subunits, we used a Xenopus laevis oocyte expression system. Injection of cAMP into oocytes expressing cardiac alpha 1 or VSM alpha 1 alone had no effect on L-VDCC activity. However, cAMP increased L-VDCC activity 2-fold in oocytes co-expressing cardiac alpha 1 or VSM alpha 1 with the skeletal muscle beta-subunit. These results suggest that the presence of the beta-subunit is required for cAMP-mediated increase of L-VDCC activity and that the characteristics of tissue-specific beta-subunits may explain differential regulation of L-VDCC activity.

[Investigation on clinical efficacy and passage into ascites of cefminox in diffuse peritonitis associated with infantile acute appendicitis]

Cefminox (CMNX), one of newly developed cephamycin antibiotics, was administered to 7 cases of diffuse peritonitis associated with infantile acute appendicitis to determine its concentrations in the blood, the appendiceal tissue and the purulent ascites and simultaneously to investigate its clinical efficacy. CMNX was intravenously injected at a dose of 20 mg/kg (at a maximum amount of 1.0 g/body) before operation and intravenously by bolus injection or by drip infusion twice daily after operation for 3 to 11 days in a total dose of 2.36 to 14.06 g. Fourteen strains of bacteria were isolated from the purulent ascites: Escherichia coli was isolated from 6 cases but superinfections in 5 cases. MICs of CMNX against these isolated organisms were at or lower than 3.13 micrograms/ml for 12 out of 14 strains. CMNX penetrated into the appendiceal tissue and the purulent ascites very well. The concentrations in the pus reached higher than those in the tissue in about 1 hour after administration and were found to reach as high as 9.63 micrograms/ml in 5 hours after administration. Its clinical efficacies were excellent in 4 cases, good in 2 cases and poor in 1 case. No subjective or objective adverse reactions were observed nor any abnormalities were found in laboratory examinations.

[Clinical evaluation of radioimmunoscintigraphy using a I-131 anti CEA and CA 19-9 monoclonal antibodies cocktail (IMACIS-1)]

The clinical usefulness of a I-131 anti CEA F(ab')2 MoAB and CA 19-9 F(ab')2 MoAB cocktail(IMACIS-1) for the localization of a cancer has been studied in 35 patients (Lung Ca. 10, Pancreas Ca. 7, Gastric Ca. 6, Colon Ca. 5, Hepatoma 2, Cholangio Ca. 2, Esophageal Ca. 1, Uterus Ca. 1, and, Retroperitoneal tumor 1). Of these 28 patients (80%) had an abnormal accumulation of radioactivity in the tumor sites (Lung Ca. 5, Pancreas Ca. 7, Gastric Ca. 6, Colon Ca. 5, Hepatoma 2, Esophageal Ca. 1, Uterus Ca. 1, and, Retroperitoneal tumor 1). Eighteen cases (56.3%) in 32 cases in which the primary site was known showed an abnormal radioactive accumulation and, similarly, 20 metastatic sites (71.4%) in 16 cases with 28 metastatic sites also showed an abnormal accumulation of radioimmunoscintigraphy showed no correlation with the serum CEA or CA 19-9 concentration. Further, no side effect was observed.

Identification of a novel 1,4-dihydropyridine- and phenylalkylamine-binding polypeptide in calcium channel preparations

A 1,4-dihydropyridine- and phenylalkylamine-binding polypeptide has been identified by photoaffinity labeling of purified rabbit and guinea pig skeletal muscle calcium channel preparations. The arylazide ligands (-)-[3H]azidopine and (-)-5-[(3-azidophenethyl)[N-methyl-3H]methylamino]-2-(3,4,5- trimethoxyphenyl)-2-isopropylvaleronitrile [( N-methyl-3H]LU 49888) were used to label 1,4-dihydropyridine- and phenylalkylamine-binding sites, respectively. A single, 155 to 170-kDa polypeptide was specifically labeled by both ligands in rabbit and guinea pig preparations provided that the skeletal muscle membranes used for purification were derived from fresh and not previously frozen and thawed tissue. The photoaffinity labeled polypeptide (termed here alpha 1) is different from the previously described alpha subunit in that it has the identical electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels irrespective of pretreatment either with N-ethylmaleimide or with dithiothreitol. The use of transverse tubular membranes isolated from previously frozen and thawed skeletal muscle results in a purified calcium channel preparation devoid of the alpha 1 subunit. In these preparations proteolytic degradation products of alpha 1 are labeled with both (-)-[3H]azidopine and [N-methyl-3H]LU 49888. Another large molecular weight polypeptide (termed here alpha 2) was also present in every purified calcium channel preparation studied. alpha 2 is distinct from alpha 1 in that reduction with dithiothreitol changes its apparent mass from 160-190 to 130-150 kDa. The alpha 2 subunit is not photoaffinity labeled either with (-)-[3H]azidopine or [N-methyl-3H]LU 49888. These data suggest that two distinct high molecular weight polypeptides (termed alpha 1 and alpha 2) are putative subunits of skeletal muscle calcium channels. Only the alpha 1 subunit contains both 1,4-dihydropyridine and phenylalkylamine receptors. alpha 2 is the same as the previously described alpha subunit (Curtis, B. M., and Catterall, W. A. (1984) Biochemistry 23, 2113-2118), but is neither a 1,4-dihydropyridine- nor a phenylalkylamine-binding protein.

3-Amino-3-deoxy-D-glucose: an antibiotic produced by a deep-sea bacterium

Gram-positive bacteria isolated from deep-sea sediments of the Pacific basin showed considerable antibacterial activity. A Bacillus strain, isolated from a sediment sample collected at a depth of 4310 m, was shown to produce 3-amino-3-deoxy-D-glucose, a known antibiotic.

Identification of sulfur-containing metabolites of m-dichlorobenzene and their disposition and relationship with glutathione in rats

The sulfur-containing metabolites of m-dichlorobenzene (m-DCB) were identified by using gas chromatography-mass spectrometry and disposition of these metabolites was studied. In the blood, urine and feces of rats dosed with m-DCB, 2,4- and 3,5-dichlorophenyl methyl sulfoxides and 3,5- and 2,4-dichlorophenyl methyl sulfones emerged, while their possible precursors, 3,5- and 2,4-dichlorophenyl methyl sulfides (Me' and Mf', respectively), were not detected in the blood, urine and feces. However, after heating the alkalinized urine and feces, the methyl sulfides appeared. Each cumulative amount of the methyl sulfoxides and methyl sulfones excreted in both the urine and feces for 120 h was less than 0.3% of the dose, while the amounts of Me' and Mf' excreted were about 0.9 and 0.2%, respectively. The amounts of 2,4- and 3,5-dichlorophenyl mercapturic acids excreted in the urine were 2.3 and 1.2%, respectively. However, the former was increased to 27.3% and the latter to 4.3% after heating the acidified urine. The cystein conjugates were not detected. The administration of m-DCB decreased the glutathione level in liver of fasted rats but it was not further reduced by diethyl maleate (DEM)-pretreatment. The kidney glutathione level was not altered by the administration of m-DCB. The blood level of methyl sulfoxides and methyl sulfones and their excretion in urine were markedly decreased in DEM-pretreated rats, while the mercapturic acids in acid-treated urine of DEM-pretreated rats were not significantly decreased. These results suggest that the methyl sulfoxides and methyl sulfones were derived from glutathione in liver and the formation process of mercapturic acids was somewhat what different from that of methyl sulfoxides and methyl sulfones.