Volatile oils of mature and juvenile leaves of Juniperus horizontalis: Chemosystematic significance

Comparison of 39 terpenoids between young (juvenile) foliage and mature (adult) foliage from naturally growing plants of Juniperus horizontalis revealed no significant differences. Canonical variate analysis of the terpenoids of J. scopulorum and J. virginiana along with the mature foliage of J. horizontalis and co-plotting juvenile foliage showed a slight loosening of the J. horizontalis group but not enough to blur taxonomic distinctions. These results stand in sharp contrast with the previous work on J. scopulorum and appear to be due to the indeterminant growth pattern seen in J. horizontalis.     

Synthesis and biological activity of brassinolide and its 22β,23β-isomer: Novel plant growth-promoting steroids

Brassinolide (2α,3α,22α, 23α-tetrahydroxy-24α-methyl-B-homo-7-oxa-5α-cholestan-6-one), a novel plant growth-promoting steroid isolated from rape pollen, and its hitherto unknown 22β, 23β-isomer were synthesized from a C-24 epimeric 60:40 mixture of 22-dehydrocampesterol (24α-methyl) and brassicasterol (24β-methyl) from oysters. The method of synthesis favored the formation of the 22β, 23β-isomer by better than 4:1. Comparative plant growth-promoting capabilities of brassinolide, both natural and synthetic, and its three side chain $\text{cis}$-glycolic isomers in the bean second internode bioassay showed that the natural and synthetic brassinolides were equally active and caused splitting of the internode at the 0.1 μg level. The least active was the 22β,23β-isomer of brassinolide. The isomers with the 22α, 23α and 24β, and the 22β, 23β and 24β configurations were highly active and were required at about 10 times the concentration of brassinolide to cause the same physiological response. In the bean first internode bioassay, an auxin-induced growth test system which employs isolated bean plant segments, the isomer with 22β, 23β and 24β configuration caused a greater response than brassinolide. Two of the four tetrahydroxy ketones obtained in the synthesis of the isomers were also active in both assays.     

Stereochemical aspects of forcing special substrate hydrazides to behave either as electrophiles or as nucleophiles during catalysis by crude papain

Restriction of hydrazides of N-blocked amino acids mainly to electrophilic action, in acylating crude papain, has been achieved by means of a large amount of aniline, with formation of insoluble anilides of N-acylamino acids. Similarly, nucleophilic behavior, on the part of a hydrazide, has been promoted by introducing a large proportion of an N-acylamino acid to produce an insoluble N¹,N²-diacylhydrazine. Achiral, chiral and racemic hydrazides and their corresponding N-acylamino acids were utilized in the study. Among the more informative combinations of reactants were Z-dl-alanine hydrazide with aniline and then with Z-glycine. A stereospecific response in the former situation produced Z-l-alanine anilide. In the latter case, a stereoselective interaction produced Z-Gly-NHNH-lAla-Z more rapidly than Z-Gly-NHNH-d-Ala-Z. The final incubation period yielded an optically pure D product. Differences in stereochemical control have been delineated in terms of different spatial aspects for interactions at the S and S′ subsites of sulfhydryl proteolytic enzymes. A racemic reactant encountered firm stereospecificity as an electrophile at the S subsite but only modest stereoselectivity as a nucleophile at the S′ subsite. The ready availability of crude papain allows an effective procedure for the synthesis of substantial quantities of diacylhydrazines.     

Membrane assembly from purified components. I. Isolated M13 procoat does not require ribosomes or soluble proteins for processing by membranes

The coat protein of coliphage M13 is an integral protein of the host-cell cytoplasmic membrane prior to its assembly into virions. It is initially synthesized as procoat, a soluble precursor with a 23 amino acid leader sequence at its amino terminus. ³⁵S-labeled procoat accumulates during an in vitro translation reaction that contains ³⁵S-methionine and RNA from M13-infected cells. Radiochemically pure procoat has been isolated from in vitro translation reactions by extraction into an organic solvent and gel filtration through Sephadex LH-60. Radiochemically pure procoat can be used as substrate in rapid and quantitative assays for leader peptidase and for leader peptide hydrolase, an enzyme that degrades the leader peptide after its release from procoat. Procoat solubility, digestion by leader peptidase and processing by membranes are affected by the presence of Mg²⁺ ion. Isolated procoat is soluble in water at low ionic strength and mildly alkaline pH as well as in detergent solutions. It is cleaved to coat protein by purified E. coli leader peptidase and by inverted E. coli inner-membrane vesicles. These properties of the purified procoat mirror those of the procoat in crude extracts. This suggests that there are no other soluble components that are necessary for the assembly of procoat into the membrane and its conversion to coat; specifically, it provides powerful evidence that protein synthesis is not involved.     

Arterial imaging with computerized fluoroscopy

Computerized fluoroscopy (CF) allows visualization of any segment of the arterial vascular system with intravenous injection of small volumes of standard iodinated contrast media. Because it avoids the risk of arterial puncture and the need for hospitalization, this technique is safer and more economical than standard arteriography. Because of these advantages, CF is likely to expand the role of arteriography in the clinical management of vascular disease. Computerized arteriographic imaging requires an intravenous power injection of 40 to 60 cc of iodinated contrast media. Immediately after injection, six to ten fluoroscopic images (1/15 sec duration) are obtained at 1.5-sec intervals. The first image serves as a mask from which subsequent images are serially subtracted by means of a digital video image processor. The sequence of different images is contrast enhanced and stored on a video disk. Video images are converted to hard copy arteriography with a standard multiformat camera. Technical failures (<5%) may result from patient motion, inadequate peripheral venous access, or extravasation of contrast media. Nearly 600 computerized intravenous arteriograms have been performed in 240 patients with peripheral vascular disease. Qualitative com-parisons with standard arteriograms suggest a close correlation between these two imaging techniques. Computerized fluoroscopy allows the identification of atheromatous plaque ulceration, stenoses, occlusions, and aneurysms. This method has been used to visualize the aortic arch and its branches, the cervical and intracranial vessels, the abdominal aorta, and arteries of the extremities. Computerized fluoroscopy has great potential as a method for safe, simple diagnostic screening and assessment of the postoperative patient.     

The radiolysis of tryptophan and leucine with32Pβ-radiation

Summary We have extended earlier experiments on the radiolysis of DL-tryptophan using³²P-radiation to longer reaction times, observing complete destruction of the tryptophan by secondary, non-radiolytic processes. We have also undertaken the irradiation of DL-leucine with³²P's at -196°, achieving radiolyses to the extents of ca. 20–30%, but observing no concomittant asymmetric bias. The implications of these observations are discussed with regard to the Vester-Ulbricht mechanism for the origin of optical activity.     

Regulation of Muscarinic Acetylcholine Receptor Concentration in Cloned Neuroblastoma Cells

Abstract: The concentration of muscarinic acetylcholine receptors in the neuroblastoma cell line NIE-115 is regulated by receptor activation. Muscarinic agonists cause a time and dose-dependent loss of [³H]quinuclidinyl benzilate binding sites from cultured cells. Muscarinic antagonists have no effect on receptor concentration and block agonist-induced regulation. The maximum decrease in steady state receptor levels is 80% and occurs within 9 h. The altered steady state concentration persists as long as agonist remains present. Upon withdrawal of agonist, the concentration of receptors returns to control levels. This increase requires protein synthesis. Kinetically, the increase in receptors following withdrawal of agonist is slower than the decrease caused by addition of agonist, suggesting that bursts of receptor activation could lower receptor levels. In harmony with this prediction, cycles in which receptors are active for 15 min and then inactive for 15 min cause a 50% decrease in receptor concentration in a 6-h period.     

Intermediate Filaments from Bovine, Rat, and Human CNS: Mapping Analysis of the Major Proteins

Abstract: Intermediate filaments were isolated by an axon-flotation method from bovine, rat, and human CNS. Gel electrophoresis showed four major proteins, having molecular weights of about 50,000, 70,000, 160,000, and 210,000, to be present in filaments of all three species. Small differences in molecular weights and major differences in relative distribution of the filament proteins were observed among species. In bovine and rat brain the predominant protein was the 50,000 band, but in human brain the 70,000 band was present in greatest amount. Each filament protein of the three species was studied by peptide mapping using limited proteolysis and cyanogen bromide cleavage. Within the same molecular weight group, filament proteins from different species gave similar maps with both techniques. Some degree of heterogeneity was also observed. However, filament proteins of different molecular weights of the same species gave distinctly different maps. These studies rule out the possibility that filament proteins from different molecular weight groups are related to each other by oligomerization; nor is it likely that the lower molecular weight proteins are derived from the subunit of molecular weight 210,000.     

Influence of Estrogen and Progesterone on Glutamic Acid Decarboxylase Activity in Discrete Regions of Rat Brain

Abstract: Female Charles River rats were ovariectomized and treated for three days with 17/8-estradiol benzoate (E) (1.0 /μg/day), progesterone (P) (500 μg/day), vehicle, or a combined treatment (2 days E, one day P). Animals were killed on day 3 and the brains were dissected by the micropunch technique. Glutamic acid decarboxylase (GAD) activity was measured by collection of ¹⁴CO². Estradiol benzoate and progesterone were potent inhibitors of GAD activity in regions such as the arcuate nucleus, ventromedial hypothalamus and corticomedial amygdala. Estrogen reduced the V_max of GAD for glutamate as a substrate without changing the K_m. Estrogen also failed to change the K_m for pyridoxal phosphate. Combined treatment with estrogen and progesterone did not reduce GAD from ovariectomized levels except in the septum, indicating an interaction of the two hormones at the level of GAD. The suggestion is made that under conditions that inhibit LH secretion GAD activity is low, but when LH secretion is stimulated GAD activity may be comparatively high.     

Catecholamine-Sensitive Guanylate Cyclase from Human Caudate Nucleus

Abstract: Partial purification of soluble guanylate cyclase on DEAE-Sephacel yields two separate peaks of guanylate cyclase activity. After 10-fold purification of the soluble enzyme, guanylate cyclase is markedly inhibited by micromolar concentrations of dopamine (I₅₀= 0.2 μm). Dopamine inhibition is observed whether the reaction is conducted with Mn²¹ or with Mg²⁺, under atmosphere or N₂(g), and using enzyme from either peak from the DEAESephacel column. Other catecholamines also inhibit partially purified guanylate cyclase with an order of potency at 1 μm of: dopamine =l -DOPA > norepinephrine = isoproterenol = adrenochrome > epinephrine. The structural requirements for inhibition are two free hydroxyl groups on the phenyl ring and an ethylamine side chain. Dopamine also inhibits the Triton X-100-solubilized microsomal guanylate cyclase after partial purification on DEAESephacel. Neither chlorpromazine, propranolol, nor phentolamine at 20 μm effectively block the dopamine inhibition of partially purified soluble guanylate cyclase. Micromolar concentrations of the reducing agents dithiothreitol and glutathione also inhibit partially purified guanylate cyclase, but unlike these agents, catecholamines can inhibit whether added in the reduced or the oxidized forms. Inhibition of enzyme activity by micromolar concentrations of dopamine, adrenochrome, or dithiothreitol is rapidly reversed by dilution and the dopamine inhibition is competitive with MgGTP. Inhibition does not appear to involve covalent binding or to result from the ability of catecholamines to reduce the concentrations of oxygen or free radicals in solution.