Mobilization of stored calcium for phasic contraction induced by norepinephrine in rabbit aorta

In Ca-free solution norepinephrine (NE) produced only a phasic contraction in the media-intima layer of rabbit aorta. The second application of NE was almost ineffective. Incubation of the muscle with Ca for a short period (Ca loading) restored the ability to produce a phasic contraction in Ca-free solution. Various ions and compounds were applied to the muscle prior to the Ca loading or prior to NE application and it was found that these treatments variously affected the NE-induced phasic contraction. The data suggest that the NE-induced phasic contraction in Ca-free solution results from Ca release from cellular sites and that a hyperbolic relationship exists between the amount of Ca at these sites and the magnitude of the contraction. These sites take up extracellular Ca by a process sensitive to La3+ but not to D600; the Ca influx stimulated by high K solution, which is sensitive to D600 and also contributes to refilling of these sites; NE releases this stored Ca by a process sensitive to procaine, caffeine and theophylline and, in this manner, elicits a phasic contraction.

[Clinical studies on PC-904 in biliary tract diseases (author's transl)]

The clinical effects of PC-904, a new semisynthetic penicillin, were studied in patients with biliary tract diseases, and the results were as follows: 1) PC-904 showed an average peak serum level of 40.7 +/- 11.6 microgram/ml 2 hours after an intravenous drip infusion of 1 g of the agent. The biliary level showed a peak value of 126.5 +/- 85.4 microgram/ml 2 hours to 3 hours after the infusion. 2) Isolated organisms from bile before the treatment were E. coli, Klebsiella, Proteus, Pseudomonas, Enterococcus and Bacteroides. MIC of PC-904 on 18 strains of isolated organisms was almost 6.25 microgram/ml or less. All isolated organisms except one strain of Klebsiella oxytoca disappeared after the treatment. 3) Six patients with cholelithiasis were medicated with PC-904 to prevent post-operative infections. The clinical effects were good in 4, poor in 1 and unknown in 1 case. 4) As to side effects no adverse reactions and allergic reactions were noted. Also no significant abnormalities of laboratory findings were observed.

[Comparative biochemical studies of placental alkaline phosphatase in animals (author's transl)]

Biochemical properties of alkaline phosphatase (ALP) from placenta were compared between man, dog, cat, rabbit and cattle. 1) Optimum pH of the enzyme was essentially identical through the species of the animals but the inhibition of L-phenylalanine was clearly demonstrable with human ALP but little with that of other animals. 2) ALP of human placenta was not inactivated by heating at 65 degrees C for 15 min. but one of the other animals was thermolabile. Such thermostability of human placental ALP almost disappeared after treatment with EDTA, suggesting that the divalent metal ions were required for the thermostability. 3) Activities of placental ALP were inhibited by cationsurfactants in human and rat but not in the other animals, while the inhibition by DOC-Na, an anion-surfactant, was seen only in human. 4) The affinity to beta-glycerophosphae of placental ALP was seen only in human.

Estrogen derivatives for the external localization of estrogen-dependent malignancy

Four radioiodinated estrogen derivatives were studied to determine their affinity for the estrogen-binding protein found in the cytosol of rabbit and rat uteri. In vitro determination of the binding properties by competitive-binding experiments and by sucrose-gradient centrifugation indicates that one of the derivatives, iodohexestrol, binds to the cytosol estrogen-binding protein. This in vitro behavior was related to in vivo distribution. Studies in immature female rats showed high uterine uptake of iodohexestrol at 2 hr (1.69% dose/gm). Iodohexestrol also has a high nonspecific binding in both the blood and the uterine cytosol. Thyroxine can diminish the nonspecific binding in vitro; in vivo the prior injection of thyroxine increased the 2-hr uterus-to-blood ratio from 1.9 to 10.4 The in vitro receptor-assay system was helpful in predicting in vivo distribution.

Iodinated bleomycin: an unsatisfactory radiopharmaceutical for tumor localization

Cobalt-57-bleomycin is a clinically useful tumor-localizing agent, but attempts to label bleomycin (BLEO) with other radionuclides have been made because of the long physical half-life of 57Co. As an alternative labeling approach, we iodinated BLEO both directly on the imidazole ring and indirectly by reaction with N-succinimidyl 3-(4-hydroxy, 3-iodophenyl) propionate. Directly iodinated BLEO retained antibacterial activity, but in tumor-bearing rats it showed a lower tumor-to-blood ratio (2.3) at 2 hr than did 57Co-BLEO (11.8). The antibacterial activity of the indirectly labeled BLEO was markedly reduced and this material showed a tumor-to-blood ratio of 0.55 at 2 hr. The radioiodinated bleomycins are not suitable substitutes for 57Co-BLEO as tumor-imaging radiopharmaceuticals.

Technetium-99m-pyridoxylideneglutamate, a new agent for gallbladder imaging: comparison with 131I-rose bengal

Two agents used for hepatobiliary studies, 131I-rose bengal and 99mTc-pyridoxylideneglutamate, have been compared in rabbits. The 99mTc radiopharmaceutical is rapidly cleared from the blood by the liver and rapidly excreted through the common bile duct into the duodenum. Because of its rapid removal from the liver, visualization of the gallbladder and biliary passages was obtained within 15 min after injection in experimental animals.

Chemical and biologic properties of isolated radiolabeled bleomycin preparations

Cobalt-57-bleomycin is a diagnostically useful radiopharmaceutical, but little is known about the nature of its individual fractions in regard to their metal-binding capacity and their in vivo distribution. Bleomycin was separated by high performance liquid chromatography (HPLC) into four major components. These were labeled and the distribution studied in tumor-bearing rats at 2 and 24 hr. In vivo radiochemical purity was also determined. Of the nine HPLC systems studied, Porasil A eluted with a mobile phase of 0.3% ammonium formate in methanol gave the best separation of the fractions. These fractions were copper free and retained their biologic activity and purity. An in vitro competitive binding study of 57Co-bleomycin with either 57Co-human serum albumin (HSA) or 57Co-ethylenediaminetetraacetic acid (EDTA) showed the labeled bleomycin to be a strong chelate. The biologic distribution in tumor-bearing rats showed significantly higher concentration in tumors at 2 hr for fractions A2 and B2 as compared to the bleomycin mixture. The other fractions, A1 and demethylA2, gave lower tumor concentrations than the bleomycin mixture. The tumor-to-blood ratios for A2 and B2 were not significantly different from the bleomycin mixture, suggesting that the concentration of the bleomycin in the tumor was related to blood concentration. Tumor-to-blood ratios of greater than 10:1 at 2 hr were achieved for A2, B2, and the mixture; ratios of greater than 31:1 were achieved at 24 hr for all three. From these data it appears that the major components A2 and B2 are the most useful for diagnostic tumor imaging.

In vitro development of resistance to erythromycin, other macrolide antibiotics, and lincomycin in Mycoplasma pneumoniae

Mycoplasma pneumoniae was made highly resistant to erythromycin in vitro by serial subculture in broth media containing erythromycin. The resistance developed to erythromycin was 200 mug/ml with the Mac strain, a prototype of M. pneumoniae, and 10 mug/ml with the Fukumura strain, an isolate. The erythromycin resistance was accompanied by cross resistance to other macrolide antibiotics (leucomycin, josamycin, spiramycin, and oleandomycin) and to lincomycin, but there was no resistance to vernamycin B. Resistance to the antibiotics developed in vitro or in vivo was stable after the microorganisms were repeatedly transferred in antibiotic-free media.