The hydrogen bond continuum in solid isonicotinic acid

The understanding and correct description of intermolecular hydrogen bonds are crucial in the field of multicomponent pharmaceutical solids, such as salts and cocrystals. Solid isonicotinic acid can serve as a suitable model for the development of methods that can accurately characterize these hydrogen bonds. Experimental solid-state NMR has revealed a remarkable temperature dependence and deuterium-isotope-induced changes of the chemical shifts of the atoms involved in the intermolecular hydrogen bond; these NMR data are related to changes of the average position of the hydrogen atom. These changes of NMR parameters were interpreted using periodic DFT path-integral molecular dynamics (PIMD) simulations. The small size of the unit cell of isonicotinic acid allowed for PIMD simulations with the computationally demanding hybrid DFT functional. Calculations of NMR parameters based on the hybrid-functional PIMD simulations are in excellent agreement with experiment. It is thus demonstrated that an accurate characterization of intermolecular hydrogen bonds can be achieved by a combination of NMR experiments and advanced computations.

Significant improvement in conversion efficiency of isonicotinic acid by immobilization of cells via a novel microsphere preparation instrument

An instrument for the automatic preparation of microspheres was designed and manufactured, and by which cells were immobilized as efficient biocatalyst with small particle diameter, high crosslinking uniformity, and high porosity. The concentration of polymer solution, crosslinking agent and other conditions for preparing the cells microspheres were determined, and the conversion conditions of isonicotinic acid from 4-cyanopyridine were optimized to minimize mass-transfer limitations, and improve thermal and storage stability. The immobilized cells microspheres, which were continuously used for 23 batches, showed a total transformation capacity of 4.6 mol/L 4-cyanopyridine and a cumulative mass of 566.31 g/L of isonicotinic acid, which demonstrated the potential of the durable biocatalyst with efficient conversion capacity.

Effect of 3d heterometallic ions on the magnetic properties of azido-Cu(II) with isonicotinic acid coligands: A theoretical perspective

Based on density functional theory and the broken-symmetry approach, the magnetic properties of an azido-Cu(II) complex with isonicotinic acid coligands were studied at the B1LYP/def2-TZVP level. According to the molecular magnetic orbitals and Mulliken spin population analysis, there are strong orbital interactions between the paramagnetic Cu^II/Ni^II ions and the bridging azide ligands and isonicotinic ions. The supposedly empty 4s/4p/4d orbitals of the M^II ions are found to play an important role in the mechanism of magnetic coupling and are probed using NBO analysis. As the number of unpaired electrons on the M^II ions increases, the number of electrons that occupy the empty 4d orbitals with the highest energy and overlap integrals of the magnetic orbitals in the Cu^IIM^II (M = Cu, Ni, Co, Fe, Mn) model complexes increases accordingly, and the magnetic coupling constant gradually decreases.

INDUCTION OF HEPATOMAS IN CBA-CB-SE MICE BY HYDRAZINE SULPHATE AND THE LACK OF EFFECT OF CROTON OIL ON TUMOUR INDUCTION IN BALB-C-CB-SE MICE

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An improved method for determination of thiocyanate in plasma and urine

An improved spectrophotometric method is described for the determination of thiocyanate in plasma and urine. Thiocyanate is adsorbed on a weak anion-exchange resin with strong affinity for chaotropic ions, and eluted with perchlorate. Thiocyanate is then chlorinated by hypochlorite and quantified according to the König (J Prakt Chem 1904; 69:105-37) reaction by use of isonicotinic acid and 1,3-dimethyl-barbituric acid. The method affords a simple, rapid and sensitive assay for thiocyanate and has a detection limit of 0.93 mumol/l. At thiocyanate concentrations of 107.1 and 167.4 mumol/l in plasma and urine the within-day CVs were 0.69% and 1.1% respectively, and the total imprecision measured for a period of 65 days was 0.98%. Analytical recoveries were quantitative both with urine and plasma samples.

Cortical GABAB and GABAA receptors in Alzheimer's disease: a quantitative autoradiographic study

GABAB and GABAA binding sites were evaluated by quantitative autoradiography of 3H-GABA binding in superior frontal gyrus of persons who died with dementia of the Alzheimer's type (DAT) and of age-matched normal controls. Scatchard analysis and competition studies disclosed 48 to 68% and 25% decrements in receptor density (Bmax) for GABAB and GABAA receptors, respectively, in layers II, III, and V of DAT frontal cortex as compared with controls. No significant difference in affinity (KD) for either GABAA or GABAB receptors was found. Our data may reflect multisystem pathologic involvement in DAT neocortex.

Effect of various GABA-receptor agonists and antagonists on anaphylactic histamine release in the guinea-pig ileum

In this paper we confirm the previously reported inhibition by GABA of anaphylactic histamine release from isolated guinea-pig ileum longitudinal muscle. Moreover we report that: GABA-inhibition of anaphylactic histamine release is mimicked both by GABA-A and GABA-B agonists; both GABA-A and GABA-B antagonists are effective in reversing GABA's inhibitory effect; the effect is exerted specifically by GABA-ergic drugs: taurine and beta-alanine are ineffective; the GABA-ergic effect seems not to involve cholinergic and adrenergic transmission. It is concluded that it might be interesting to assess the clinical value of GABA-ergic drugs in allergic gut disorders.

Functional evaluation of a corticosteroid molecule activity, dexamethasone-isonicotinate, by aerosol dosage in obstructive lung disease

The authors experimented with a corticosteroid molecule, dexamethasone-isonicotinate, by pressurized aerosol, testing it on 15 subjects suffering from a bronchial obstructive syndrome (7 cases of asthmatic bronchitis, 6 of chronic bronchitis with pulmonary emphysema, 2 of bronchial asthma). In such patients clinical evolution, spirographic patterns, and airway resistance were studied by means of body plethysmograph before and after administration of 0.25 mg dexamethasone-isonicotinate four times a day. In four subjects daily variations of airway resistance before and after 10 days of treatment were evaluated: in three cases the resistance diminished noticeably at all times of the day after therapy. In eleven cases the functional parameters were recorded before and after 7 days therapy, and ten subjects were followed up by a monthly, check during 6 months of therapy. In both methods, the authors obtained good or very good results in more than half of the subjects and fair results in a fifth of the subjects; in the remaining patients poor results were obtained. Side-effects attributed to improper dosage were never observed.

Enhanced migration of the ionized forms of acidic drugs from water into chloroform in the presence of phospholipids

The transfer process of various acidic drugs from water into chloroform containing phospholipids has been examined using a nonemulsifying system. The ionized forms of the drugs which have little lipid solubility show a marked increase in transfer to the chloroform phase containing lecithin at the physiological pH of the small intestine. The pH-profiles of salicylic acid, p-aminobenzoic acid and sulphisoxazole transfer are in good agreement with available in situ absorption data. These results suggest a role for phospholipids in the intestinal absorption of ionized acidic drugs which has not been clearly apparent with pH-partition hypothesis alone.