Effect of Cimetidine and other antihistaminics on the elimination of aminopyrine,phenacetin and caffein

Cimetidine is widely prescribed for the treatment of peptic ulcer disease and has recently been shown to inhibit the metabolism of warfarin, antipyrine and diazepam. To further examine this phenomenon we investigated the effect of various doses of cimetidine and other related drugs on ¹⁴C-aminopyrine, ¹⁴C-phenacetin and ¹⁴C-caffeine breath tests. Cimetidine caused a dose-related inhibition of the metabolism of aminopyrine and caffeine but had no effect on the phenacetin breath test. Metiamide, H₁-antihistamines, phenothiazines and local anesthetics also inhibited the aminopyrine breath test. Cyproheptadine had no effect on either phenacetin or caffeine elimination. This study demonstrates a complex drug-drug interaction which may have widespread clinical implications.     

Immunity to Epstein-Barr virus in Hodgkin's disease preceded by infectious mononucleosis

A patient who developed Hodgkin''s disease four years after infectious mononucleosis had elevated serum antibody titres to Epstein-Barr virus and delayed hypersensitivity reactions to membrane antigens prepared from fresh autologous spleen, from spleen cells of another Hodgkin''s patient, and from cell lines known to carry the Epstein-Barr virus genome. Additional studies in more lymphoma patients will be needed to determine the significance of the reactivity against tumour and virus-associated antigens which has been documented in this patient.     

The role of the conjugated carbonyl of cytochalasin A in contractility inhibitions

A study of the mechanism of action of cytochalasin A (CA) in relation to its structural features and to its selective inhibition of certain contractile processes has been initiated. Quantitative structure-function analyses with several CA-related cytochalasins — including synthetic 21, 22-dihydro-CA (DHCA), the 22-β-mercaptoethanol CA-adduct, (CA-2ME), and the 22-dithiothreitol CA-adduct (CA-DTT) — have been carried out in a temperature sensitive gel-sol extract from Ehrlich ascites tumor cells. Each drug congener was purified to homogeneity by HPLC prior to biological testing. The undiminished inhibitory indices of DHCA and CA-2ME $\text{(}\text{ID}{}_{\mathrm{5\; 0}}\text{? 3.7 × 10}{}^{\mathrm{?7}}\text{M}\text{)}$ overrules the prior circumstantial evidence accumulated for the obligatory electrophilic interaction of this drug, at its α-β-unsaturated ketone region, with presumptive receptor nucleophiles.     

Peripartum Cardiomyopathy Presenting With Ventricular Tachycardia: A Rare Presentation

A 25-year-old previously asymptomatic pregnant woman at 36 weeks'' gestation was noticed to have repetitive monomorphic ventricular tachycardia. A dilated left ventricle with moderately reduced systolic function was found on echocardiographic examination. This is a very rare presentation of peripartum cardiomyopathy (PPCMP) presenting with repetitive monomorphic ventricular tachycardia.     

Poly(vinyl amine)-silica composite nanoparticles: models of the silicic acid cytoplasmic pool and as a silica precursor for composite materials formation

The role of polymer (poly(vinylamine)) size (238-11000 units) on silicic acid condensation to yield soluble nanoparticles or composite precipitates has been explored by a combination of light scattering (static and dynamic), laser ablation combined with aerosol spectrometry, IR spectroscopy, and electron microscopy. Soluble nanoparticles or composite precipitates are formed according to the degree of polymerization of the organic polymer and pH. Nanoparticles prepared in the presence of the highest molecular weight polymers have core-shell like structures with dense silica cores. Composite particles formed in the presence of polymers with extent of polymerization below 1000 consist of associates of several polymer-silica nanoparticles. The mechanism of stabilization of the "soluble" silica particles in the tens of nanometer size range involves cooperative interactions with the polymer chains which varies according to chain length and pH. An example of the use of such polymer-poly(silicic acid) nanoparticles in the generation of composite polymeric materials is presented. The results obtained have relevance to the biomimetic design of new composite materials based on silica and polymers and to increasing our understanding of how silica may be manipulated (stored) in the biological environment prior to the formation of stable mineralized structures. We suspect that a similar method of storing silicic acid in an active state is used in silicifying organisms, at least in diatom algae.     

Lipofuscin like compound in mango

Thin layer chromatographic separation of chloroform-methanol extracts of mango on silica gel revealed a fluorescent substance in mango peel and pulp. The compound had fluorescence spectrum similar to that of lipofuscin, the age pigment of animal tissues and was found to be water insoluble and stable to ultraviolet irradiation. The fluorescent material appeared to be a lipoprotein.     

Luteal phase variations in endogenous concentrations of prosta-glandins PGE and PGF and in the capacity for their in vitro formation in the human corpus luteum

One evidence for a luteolytic role for prostaglandin F₂α in the human is the increase in luteal PGF at times corresponding to luteolysis as reported earlier by us and other groups. There have been other contradictory reports on this point. In the present experiments we have measured the concentrations of PGE and PGF in 16 more human corpora lutea and have determined the capacity of those tissues to form PGE and PGF in vitro. PGF concentrations were highest in the mid luteal phase but were accompanied by high PGE concentrations. On the other hand, in the late luteal phase PGF concentrations, lower than in mid luteal but generally higher than in early luteal phase, were significantly higher than PGE concentrations. This pattern in PGE and PGF concentrations was also evident in the capacity of these tissues to form these compounds in vitro. In view of the known capacity of PGE₂ to counteract the luteolytic effect of PGF₂α, these variations in the relative concentrations of PGE and PGF during the luteal phase may be of significance in the process of luteolysis in the human.