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M Boca

Publications and source records attributed to M Boca.

At least 19 recordsLinked to original sources
PubMed2001

Strong cooperativeness in the mononuclear iron(II) derivative exhibiting an abrupt spin transition above 400 K.

The spin crossover system, [Fe(bzimpy)(2)](ClO(4))(2).0.25H(2)O, was reinvestigated above room temperature (bzimpy = 2,6-bis(benzimidazol-2-yl)pyridine). The system exhibits an abrupt low-spin to high-spin transition at T(c) = 403 K. Liberation of a fractional amount of water does not affect the spin crossover: the system is perfectly reversible with a hysteresis width of DeltaT = 12 K. The existence of the hysteresis at such high temperature determines that the lowest limit of the solid-state cooperativity parameter is J/k > 403 K despite long iron(II) separations (10 A). The high cooperativeness has been assigned to a perfect pi-stacking of the benzimidazole rings in the crystal lattice at a distance as short as 3.6 A. Variable-temperature IR data and the heat capacity measurements match well the magnetic data. The thermodynamic properties are DeltaH = 17 kJ mol(-)(1), DeltaS = 43 J K(-)(1) mol(-)(1), so that the entropy of the spin transition shows a considerable contribution from the molecular vibrations. A theoretical model has been applied in fitting the magnetic data along the whole hysteresis path. A statistical distribution of the cooperativity parameter led to the feature that angled walls of the hysteresis loop are well reproduced.

Journal Article↗
PubMed2000

Selective imidazolidine ring opening during complex formation of iron(III), copper(II), and zinc(II) with a multidentate ligand obtained from 2-pyridinecarboxaldehyde N-oxide and triethylenetetramine.

The condensation of 2-pyridinecarboxaldehyde N-oxide and triethylenetetramine yields a product with two imidazolidine rings, as proven by a solid-state X-ray structure analysis as well as by NMR solution spectra. This ligand, L1, undergoes a ring-opening reaction on complex formation with Cu(II), yielding [CuL2]2+ where L2 functions as a pentadentate ligand, containing only one imidazolidine ring. On complexation with Zn(II) and Fe(III), both rings are opened and the complexes [ZnL3]2+ and [FeL3]3+ with a hexadentate L3 ligand are formed. The recrystallization of [ZnL3]2+ from DMSO solution results in the complex [ZnL1(DMSO)2]2+ in which L1 behaves as a tetradentate ligand. Thus L1, L2, and L3 are structural isomers with two, one, or no imidazolidine rings, as confirmed by X-ray structure analyses. The intramolecular ring formation is the result of the nucleophilic addition of the N(amino) group to the electrophilic sp2-hybridized -HC delta+=N site. Owing to the absence of the chelate effect on the sp3-hybridized carbon atom belonging to the imidazolidine ring, the ring opening is facilitated and readily observed upon complex formation with Cu(II), Zn(II), and Fe(III).

Journal Article↗
PubMed2000

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Journal Article↗
PubMed1996

[Lactilol (Importal, 10g in powder made by ZYMA) in the treatment of portal systemic encephalopathy].

In a group of 15 patients with portal systemic encephalopathy (PSE) associated with cirrhosis of the liver with portal hypertension and spontaneous systemic shunt of the portal circulation the authors administered Lactitol (Importal, powder à 10 g Zyma), in amounts up to 40 g/day for a period of 56 days. In the course of treatment every patient was repeatedly examined before the onset of treatment and three times during treatment. The grade of PSE was assessed on the basis of the score of the neuropsychiatric examination from which the PSE index was worked out. In the investigated group of patients with PSE the authors found a significant improvement of the PSE index during treatment with Importal Zyma. The mental condition of the patients improved, the NCT period was reduced, asterixis receded, on the EEG the delta and theta activity receded and normal alpha activity developed. The serum ammonia levels declined but did not reach statistical significance. During treatment the authors did not record changes of normal values of glucose, sodium and potassium in serum and did not detect any adverse side effects. Based on the assembled results the authors conclude that lactitol treatment extends possibilities of PSE treatment.

Adult↗
PubMed1991

Biochemical pattern of the ascitic fluid in liver cirrhosis and in neoplastic diseases.

In 22 subjects with liver cirrhosis and in 18 with malignancy, both with ascites, 10 biochemical parameters have been investigated in ascitic fluid. The evaluation of data by cluster analysis, optimized with the aid of multivariate normality testing, was able to recognize correctly a majority of cases. For diagnosis of malignancy, an 89% sensitivity and 82% specificity was obtained. The described way of data collecting and processing is recommended for the clinical practice.

Ascitic Fluid↗
PubMed1990

[Essential phospholipids in the treatment of chronic hepatitis B virus infection].

The authors investigated 24 patients with chronic infection with the hepatitis B virus. HBeAg-positive patients had significantly (alpha = 0.05) more frequently pathological initial values of biochemical and immunological indicators, as compared with anti-HBe-positive patients. Delta antigen in the liver and anti-delta antibodies in serum if examined, were always negative. All patients were subjected to 16-week treatment with Essentiale forte (Natterman). After treatment and after the subsequent 16 weeks in none of the patients loss of HBsAg or seroconversion of HBeAg-positive to anti-HBe-positive was recorded. In the sub-group of HBeAg-positive subjects after treatment a significant drop of gamma-globulins and circulating immunocomplexes occurred, in the sub-group of anti-HBe-positive subjects a significant rise of active and total T-lymphocytes was found. The authors recommend to test Essentiale forte in the prevention and treatment of immunocomplex disease in chronic infection with the hepatitis B virus.

Adult↗
PubMed1989

[Larval toxocariasis--a severe course of the manifest infection].

The case of a 17 year old patient with severe course of toxocariasis is reported. Over a period of 6 months the patient developed signs of serious systemic condition with fever, respiratory infections, diarrhea, urticaria, weight loss, and muscular atrophies. The most remarkable organ derangements involved bilateral exudative neuroretinitis, severe degree of peripheral motoneuron derangement, and grave kidney damage with developing polyuria, hypokalemia, metabolic alkalosis and therapeutically hardly tractable hypertension. The most important laboratory findings were high erythrocyte sedimentation, absolute and relative eosinophilia, and hypergammaglobulinemia. Serological examination exhibited weak larval toxocariasis positivity. Treatment with Mintezol and subsequent administration of prednisone resulted in complete restoration of the clinical state, including organ and laboratory manifestations. The reported case documents the occurrence of larval toxocariasis in our population as well as the possibility of a very severe course of this parasitic infection in man. The therapeutic effect is remarkable since literary data have so far reported mostly unsatisfactory results of toxocariasis treatment.

Adolescent↗
PubMedDate not supplied

[Hemorrhagic accidents in palatal tonsil surgery].

Here is shown that, even though tonsillectomy is the most frequently performed operation in ORL, it may sometimes cause severe hemorrhaging that could imperil the patient's life if not rapidly and competently dealt with. Tonsil hemorrhaging is favoured by the anatomical situating, tonsils being greatly vascularized, as well as by the specific of the pharyngeal wounds. There are discussed here the cases in the Bistriţa ORL Clinic between 1981-1987.

Humans↗