On the diphasic nature of vasovagal fainting associated with blood-injury-illness phobia

A detailed psychophysiologic analysis of a vasovagal faint occurring in a "blood-injury-illness" phobic demonstrated that the syncopal episode consisted of a diphasic response. This lends support to the hypothesis that vasovagal fainting in these patients is caused by an overcompensating rebound parasympathetic activation following sympathetic arousal. Treatment and research implications of this finding are discussed.     

Analysis of Cell Types Identifiable In Air-Dried Cell Preparations of Human Testis

Abstract. The mixed cell population of the testicular epithelium has been studied in air-dried cell preparations obtained from a testicular biopsy. Observed cell types are defined, quantified and assigned to cell stages of the spermatogenic cycle. Studies with tritiated thymidine helped to categorize the spermatogonial cell types. Variation in cell size within cell categories, variation in frequency of cells in different categories within individuals, and variation in frequency of cells within categories between individuals were subjected to quantitative analysis.     

Solubilization of the calcium antagonist receptor from rat brain

[3H]Nitrendipine binds with high affinity to a calcium antagonist receptor in rat brain membranes. At 4 degrees C, treatment with digitonin solubilized the calcium antagonist receptor as a stable complex with [3H]nitrendipine. The nitrendipine concentration that gave a half-maximal amount of the solubilized [3H]nitrendipine-receptor complex was identical to the Kd for specific nitrendipine binding to brain membranes. Nitrendipine dissociated from digitonin-solubilized and membrane-bound receptors with a half-time of 24 to 30 min at 20 degrees C. Verapamil increased and diltiazem decreased the dissociation rate to a similar extent in both preparations indicating that the solubilized receptor contains both the dihydropyridine and diltiazem/verapamil binding sites. Sucrose gradient sedimentation experiments gave a value of S20, omega = 19.2 for the receptor-digitonin complex. The solubilized calcium antagonist receptor binds specifically to wheat germ agglutinin-Sepharose columns consistent with an identification as a glycoprotein.     

Haemolysis of rabbit erythrocytes by a lectin from the seeds of<Emphasis Type="Italic">Croton tiglium</Emphasis>

The kinetics of haemolysis of rabbit erythrocytes byCroton tiglium lectin was studied as a function of concentration of the lectin and erythrocytes. The length of the prelytic period decreased with increasing lectin concentrations, indicating that the secondary events at the membrane which follow the binding of the lectin to cell surface carbohydrate receptors are accelerated at higher surface concentrations of the lectin. The rate or extent of haemolysis was not affected by the inclusion of ions like K⁺, Ca²⁺ and Mg²⁺ in the medium or by the substitution of ionic medium by a non-ionic medium. The inhibition of haemagglutination and haemolysis of rabbit red cells byCroton tiglium lectin by antilectin rabbit serum was observed. A possible mechanism of haemolysis by the lectin is discussed.     

Plant lectins specific for N-acetyl-β-D-galactosamine

N-Acetyl-D-galactosamine in β-linkage being ubiquitous in cell surface glycoproteins, their interaction with lectins specific for this sugar moiety may be a significant event in cell adhesion phenomena. This article discusses the common β-N-acetyl galactosamine-specific lectins, with particular stress on the lectin from winged beans (Psophocarpus tetragonolobus).     

“Pleiotypic Response”

A hypothesis has been developed to relate stringent control in bacteria to a set of interactions involved in the regulation of growth of transformed and untransformed mammalian cells.     

Inhibition of DNA Synthesis but not of Poly-dAT Synthesis by the Arabinose Analogue of Cytidine <Emphasis Type="Italic">in vitro</Emphasis>

Kimball and Wilson¹ reported that the arabinose analogue of cytidine (ara-C) inhibited DNA polymerase in a crude extract prepared from Ehrlich ascites cells. Furth and Cohen² observed cytosine arabinoside triphosphate (ara-CTP) inhibited DNA polymerase in extracts from either calf thymus or bovine lymphosarcoma tissue, although these investigators³ had already found no effect of ara-CTP on DNA polymerase from Escherichia coli. The inhibition in both of these cases could be substantially reversed by dCTP; but incorporation of the arabinose nucleotide (ara-CMP) into DNA could not be unequivocally demonstrated. Graham and Whitmore⁴ reported the incorporation of ara-C into DNA in vivo and the inhibition of a DNA polymerase from L cells by ara-CTP. They found that ara-CMP was initially incorporated into small DNA strands but subsequently appeared in long strands. Momparler⁵ has presented evidence that, in vitro, ara-C incorporation was limited to the 3′-hydroxyl end of DNA chains. Such incorporation might be expected to block further chain elongation but this expectation was not supported by the evidence presented by Graham and Whitmore.     

Endopeptidase Activity of Phage λ-Endolysin

JACOB and Fuerst^1,2 demonstrated the presence of a bacteriolytic enzyme (λ-endolysin) in the induced cultures of lysogenic Escherichia coli K12 (λ). The enzyme was later identified as the product of gene R; of phage λ³ which is involved in bacterial lysis at the end of a latent period. The enzyme is apt to form spheroplast-like structures in E. coli² and one would therefore expect its substrate to be murein.     

Effects of anhydrous benzoylation on staining with a variety of protein end-group methods

Summary The effects of anhydrous benzoylation were examined in connection with the following protein end-group methods: diazosulfanilic acid — Azure A, the Sakaguchi reaction and a fluorescent variant, the phenanthrequinone fluorescent method for arginine, the Millon reaction, the Morel-Sisley reaction, the mercury orange method, the alloxan and ninhydrinShiff methods, the Dansyl-chloride fluorescent method for lysine, the dimethylaminobenz-aldehydenitrite (DMAB) method for tryptophan, and the acid fluorochrome brilliant sulfoflavin used at pH 2.8 as a stain for basic groups. With all of these methods except the DMAB method for tryptophan, selective blockage of cytoplasmic proteins and staining of nuclei was obtained. With the DMAB reaction, the results were reversed: cytoplasmic staining exceeded nuclear staining after benzoylation.