Crystal structure and optical and magnetic properties of Pr(2)(MoO(4))(3).

Praseodymium molybdate Pr(2)(MoO(4))(3) was synthesized using the standard ceramic route. The crystal structure of the material has been successfully solved in superspace group I2/b(alphabeta0)00 with lattice constants a = 5.30284(4), b = 5.32699(3), c = 11.7935(1) A, gamma = 90.163(1) degrees , and the modulation vector q = 2/3a* + 0.88810(2)b*. The deviation of the q vector from a rational value allows a description of the structure in terms of nanosize domains with the La(2)(MoO(4))(3)-like structure separated by stacking faults. Under 450 nm excitation, ((3)P(0) level) Pr(2)(MoO(4))(3) exhibits the characteristic red emission, with the most intense band at 649 nm corresponding to a (3)P(0) --> (3)F(2) transition. Magnetic susceptibility measurements reveal Curie-Weiss paramagnetism with predominating antiferromagnetic interactions between Pr(3+)-magnetic moments and no evidence of magnetic transitions down to T = 5 K.

Contactless ultrasonic device to measure surface acoustic wave velocities versus temperature.

A complete optical experimental setup for generating and detecting surface acoustic waves [Rayleigh waves (RWs)] in metals versus temperature up to the melting point is described. The RWs were excited by a pulsed Nd:YAG laser and detected by a high sensitivity subangstrom heterodyne interferometer. A special furnace was used to heat the sample using infrared radiation with a regulation of the sample temperature less than 0.1 K. First measurements on an aluminum alloy sample are presented to validate the setup.

Flavonoid-related modulators of multidrug resistance: synthesis, pharmacological activity, and structure-activity relationships.

A series of 28 flavonoid derivatives containing a N-benzylpiperazine chain have been synthesized and tested for their ability to modulate multidrug resistance (MDR) in vitro. At 5 microM, most compounds potentiated doxorubicin cytotoxicity on resistant K562/DOX cells. They were also able to increase the intracellular accumulation of JC-1, a fluorescent molecule recently described as a probe of P-glycoprotein-mediated MDR. This suggests that these compounds act, at least in part, by inhibiting P-glycoprotein activity. As in other studies, lipophilicity was shown to influence MDR-modulating activity but was not the only determinant. Diverse di- and trimethoxy substitutions on N-benzyl were examined and found to affect the activity differently. The most active compounds had a 2,3, 4-trimethoxybenzylpiperazine chain attached to either a flavone or a flavanone moiety (13, 19, 33, and 37) and were found to be more potent than verapamil.

Prevention of arrhythmias by flecainide after noncardiac thoracic surgery.

Cardiac arrhythmias are a frequent complication after thoracic operations. The prophylactic value of flecainide administered as a constant-rate, intravenous infusion (0.15 mg/kg/h) after a loading dose (2 mg/kg) was tested in a randomized, placebo-controlled study in 30 patients using Holter monitoring during the first 72 hours after operation. A high incidence of atrial and complex ventricular arrhythmias was observed in the placebo-treated group, with a clear predominance in patients undergoing left thoracotomy. Antiarrhythmic drugs had to be added in 6 patients in the placebo-treated group (n = 16), but in none in the flecainide-treated group (n = 14) (p less than 0.01). The preventive effect of flecainide was observed at serum concentrations in the middle of the therapeutic range (409 ng/mL) without side effects. It is concluded that flecainide administration effectively reduced or prevented cardiac arrhythmias after thoracic operations.

Long-time survival of a patient with glioblastoma and Turcot's syndrome. Case report.

A rare case of Turcot's syndrome is reported in a long-time survivor of glioblastoma multiforme. The patient was treated for his tumor in 1976 with macroscopically complete surgical resection and radiotherapy consisting of 60 Gy to the tumor bed and 40 Gy to the whole brain. Five years later, in 1981, he developed adenocarcinoma of the colon Dukes Stage B which was successfully treated at another hospital by surgery alone. In 1990, he presented with multiple colon polyps and adenocarcinoma Dukes Stage A. For more than 15 years, the patient has been afflicted with cystic and conglobate acne. Possible mechanisms and treatment with 13-cis retinoic acid are discussed.

Partial cricoid resection with primary tracheal anastomosis for subglottic stenosis in infants and children.

Fifteen infants and children with a severe subglottic stenosis underwent a partial cricoid resection with primary tracheal anastomosis. The etiology of the stenosis was congenital in 3 cases and was acquired after prolonged intubation in 12. Fourteen patients were tracheotomy dependent at the time of surgery, and 13 (87%) of the 15 were classified grade III (7 cases) and IV (6 cases) according to Cotton. The resection included the cricoid only in 5 cases and the cricoid and a segment of trachea (1 to 4 rings) in 10 cases. Decannulation was achieved after a single open procedure in 14 (93%) of the cases. The authors encountered no lesion of the recurrent laryngeal nerves and no fatalities. There was, however, 1 restenosis. Twelve cases were decannulated within 6 months, most of them at 2 months. The postoperative voice is normal in 10 cases, and a slight dysphonia is present in 4 cases. Twelve patients show no exertional dyspnea, and 2 exhibit a slight stridor while practicing sports. Ten of 14 cases have been followed for more than 5 years, with the longest follow-up now being 14 years. In all cases, the laryngotracheal development is normal. The results of this small series compare favorably with those of laryngotracheoplasty procedures usually performed for subglottic stenosis in infants and children. In the future, partial cricoid resection with primary tracheal anastomosis should be considered as an important treatment option for severe subglottic stenoses in infants and children.

Effects of intravenously infused fish oil on platelet fatty acid phospholipid composition and on platelet function in postoperative trauma.

BACKGROUND: The aim of this study was to assess the short-term effect of IV infusion of fish oil emulsion on the fatty acid profiles of platelet phosphatidylcholine and phosphatidylethanolamine and on platelet function in postoperative patients. METHODS: Over a 7-day period, 10 patients received a 20% soybean fat emulsion with an added 10% marine fish oil emulsion, whereas 9 controls received only 20% soybean fat emulsion. RESULTS: By comparison with controls, in patients receiving fish oil, (1) a large increase in eicosapentaenoic acid (20:5n-3) was observed in both platelet phosphatidylcholine (1.55% +/- 0.17% vs 0.38% +/- 0.06% by weight, p < .01) and phosphatidylethanolamine 2.21% +/- 0.18% vs 0.66% +/- 0.08% by weight, p < .01); (2) eicosapentaenoic acid (20:5n-3)/arachidonic acid (20:4n-6) ratios doubled in both platelet phosphatidylcholine (p < .01) and phosphatidylethanolamine (p < .05); (3) with collagen as aggregating factor, maximal reaction speed decreased (p < .02) and latency increased (p < .002); and (4) no toxic effect, in particular no increase of postoperative bleeding and no perturbation of hepatic and renal function, was observed during the fish oil infusion. CONCLUSIONS: A short-term IV infusion of fish oil clearly modifies the platelet composition and changes some parameters of platelet function.

Effects of intravenously infused egg phospholipids on lipid and lipoprotein metabolism in postoperative trauma.

Lipid emulsions contain not only triglyceride (TG)-rich particles but also phospholipid (PL)-rich particles that are believed to trap free cholesterol and apoprotein E, when they are infused in excess. The present study was designed to evaluate the effects of such abnormal PL-rich particles on lipid metabolism during a 5-day infusion in man. Eighteen patients undergoing esophagectomy were evenly randomized to receive intravenously during 5 days 1.75 g.kg-1.d-1 long-chain TG from either a 10% lipid emulsion with a PL/TG weight ratio of 0.12 (group A), a 10% emulsion with a PL/TG weight ratio of 0.06 (group B), or a 20% emulsion with a PL/TG weight ratio of 0.06 (group C). Plasma PL, free cholesterol, and apoprotein E increased progressively in group A (4.1 +/- 0.3 mmol/L, 2.4 +/- 0.3 mmol/L, and 0.089 +/- 0.012 g/L on day 5, respectively) but not in groups B (2.7 +/- 0.3 mmol/L, 1.3 +/- 0.2 mmol/L, and 0.048 +/- 0.007 g/L) and C (2.4 +/- 0.2 mmol/L, 1.2 +/- 0.1 mmol/L, and 0.050 +/- 0.006 g/L). Free fatty acids and TGs remained constant and similar in each group postoperatively. After fat infusion had been stopped at the end of the fifth day, the elimination of plasma TGs over the next 4 hours was comparable in the three groups. We conclude that excess egg PLs induce alterations of plasma lipids even within a few days.

Phase-transition-induced twinning in the 1:1 adduct of hexamethylenetetramine and azelaic acid.

The title compound, C(6)H(12)N(4).C(9)H(16)O(4), undergoes several thermotropic phase transitions. The crystalline structure is layered, with sheets of azelaic acid linked to sheets of hexamethylenetetramine by hydrogen bonds. In the room-temperature phase, the azelaic acid molecules are disordered. By lowering the temperature, this disorder partially disappears. The ordering is clearly observed in reciprocal space where on the rods of diffuse scattering, present in the room-temperature phase, a series of superstructure reflections emerges. This phase transition leads to twin-lattice quasi-symmetry (TLQS) twinning. The structure of this twinned phase is explored in this paper. There are two orientational domains linked by a mirror plane which relates disordered orientations of the acid molecules above the phase transition. A single domain has space group P2_1/c. The structure has been solved and refined on the complete set of data to R(1) = 0.0469. The chains remain partially disordered, showing two acid groups with unequal population: the major form corresponding to a carboxylic acid and the minor to a carboxylate. The ordering of the structure, when going through the phase transition, is interpreted in terms of stabilization by C-H.O hydrogen bonding. A least-squares estimator of the twinning volume ratio is developed that gives an expression for the twinning ratio in terms of the intensities of nonoverlapping reflections. The twinning ratio obtained in the structure refinement compares very well with that obtained from this estimator.

Modulated structure of La2Co1.7 from neutron and X-ray diffraction data

An La(2)Co(1.7) crystal was investigated by single-crystal neutron and X-ray diffraction. The neutron measurement was performed with a Laue white-beam technique at 15 K and room temperature, using a large position-sensitive detector. The X-ray measurements were obtained at room temperature from a CCD detector. The average structure of La(2)Co(1.7) is hexagonal with cell parameters a = 4. 885 (1), c = 4.273 (2) A and space group P6(3)/mmc. The satellites are located at the vertices of small hexagons perpendicular to the c axis. The modulated crystal was indexed assuming a sixfold twinned 3 + 1 dimensional structure with q = (alpha, 0, gamma). The structure was solved in the pseudoorthorhombic cell, with a = 8.461 (1), b = 4. 885 (1), c = 4.273 (2) A, in the superspace group C2/m(alpha, 0, gamma). Owing to space requirements, the Co atoms cannot fit precisely into the octahedral sites of the La h.c.p. (hexagonal close packing). Instead, the Co atoms adopt a different periodicity, which is not commensurate with the periodicity of the La atoms. Two structure models have been refined in order to describe this behaviour, one using the sawtooth function for the positional modulation of cobalt and the other describing the structure as a composite system. The chemical composition calculated from the composite model is La(2)Co(1.8 (1)) with the estimated standard deviation arising from the variation of q for different samples. In both models lanthanum is incommensurately modulated, while the position of cobalt seems not to be affected by any relative periodic displacement.

Combined small-cell and transitional cell carcinoma of the renal pelvis. A light microscopic, immunohistochemical, and ultrastructural study of a case with literature review.

Primary small-cell carcinomas of the kidney are rare, locally aggressive, and rapidly fatal neoplasms in elderly people. We report an example of combined small-cell and transitional cell carcinoma of the renal pelvis in a 71-year-old woman who had a history of heavy smoking. The cells that pertained to the small-cell component were morphologically mostly of an intermediate type. Immunohistochemically, they reacted with synaptophysin, carcinoembryonic antigen, and epithelial markers (Lu-5, EAB902, EAB903, and cytokeratin 19), and they contained scanty neurosecretory granules at the ultrastructural level. We review the literature on small-cell carcinoma of the kidney and renal pelvis, and we discuss the histogenesis of such a tumor.

[Surgical treatment of exogenous morbid obesity: results of Mason's vertical gastroplasty]. / Traitement chirurgical de l'obésité morbide exogène: résultats de la gastroplastie verticale selon Mason.

Among the various surgical methods of treating exogenous morbid obesity, Mason's vertical gastroplasty has gradually become the method of choice throughout the world. The method is relatively simple and the operating time short, so that if offers the great advantage of maintaining normal digestive activity free of metabolic disturbances. Between December 1981 and December 1988 we treated 160 patients in this way, the mortality in the series being nil. The results obtained are encouraging, since among 75 patients followed up for at least 2 year, 50 (66%) had a weight index between 20 and 25, 15 (20%) a weight index between 25 and 30, while 10 patients (14%) failed to respond to the treatment.