The exploration of the crystal nucleation parameters and physico-chemical analysis of a single crystal: 2-amino-4,6-dimethoxypyrimidinium hydrogen (2R,3R)-tartrate 2-amino-4,6-dimethoxypyrimidine

This paper discusses the structural orientations and the physico-chemical properties of a single crystal of 2-amino-4,6-dimethoxypyrimidinium hydrogen (2R,3R)-tartrate 2-amino-4,6-dimethoxypyrimidine (2ADT). The experimental investigation of the properties of the compound improves the potential for the utilization of the crystalline compound in the fabrication of optical limiting and nonlinear optical devices. For the growth process, an organic nonlinear optical crystal of 2ADT is synthesized conventionally at varying molar concentrations to achieve an excellent yield. The structural orientations and refinements of the compound are identified and discussed with reference to a single crystal X-ray diffraction study and its supporting computations. The results of the experimental analysis via UV-vis-NIR spectrometry and a z-scan setup with a laser beam source are used in an in-depth discussion on the linear and nonlinear optical properties of the crystal together with its damage threshold induced by a Nd:YAG laser beam at 1064 nm. With optical transparency of 55% in the entire visible region, a lower cut-off wavelength at 228 nm, and a bandgap at 5.2 eV, the crystal was demonstrated to be suitable for use in optical device fabrication. The thermogravimetrically assessed thermal stability of 2ADT was examined up to 147 °C. In addition, the thermodynamic parameters responsible for activation reactions are also discussed because these give information about the material''s thermal behavior. An optical limiting study revealed that the transmitted output power increases linearly with the input power at about 1.89 mW cm⁻².

This paper discusses the structural orientations and the physico-chemical properties of a single crystal of 2-amino-4,6-dimethoxypyrimidinium hydrogen (2R,3R)-tartrate 2-amino-4,6-dimethoxypyrimidine (2ADT).     

Prevalence of asymptomatic left ventricular systolic dysfunction in hypertensive Nigerians: echocardiographic study of 832 subjects

Background

We sought to determine the prevalence of echocardiographically determined left ventricular systolic dysfunction in asymptomatic hypertensive subjects seen in Abeokuta, Nigeria.

Methods

Echocardiography was performed in 832 consecutive hypertensive subjects referred for cardiac evaluation over a three-year period.

Results

Data were obtained in 832 subjects (50.1% women) aged 56.0 ± 12.7 years (men 56.9 ± 13.3 years, women 55.0 ± 12.0 years, range 15–88). The prevalence of left ventricular systolic dysfunction (LVSD) was 18.1% in the study population (mild LVSD = 9.6%, moderate LVSD = 3.7% and severe LVSD = 4.8%). In a multivariate analysis, male gender, body mass index and LV mass were the predictors of LVSD.

Conclusion

Significant numbers of hypertensive subjects in this study had varying degrees of left ventricular systolic dysfunction. Early introduction of disease-modifying drugs in these patients, such as angiotensin converting enzyme inhibitors or angiotensin receptor blockers may retard or prevent the progression to overt heart failure.     

Fluid resuscitation in infantile hypertrophic pyloric stenosis

The purpose of this analysis was to investigate biochemical disturbances at presentation and initial fluid resuscitation before surgery in infantile pyloric stenosis. The charts of 139 consecutive infants (113 boys and 26 girls) between 7 d and 20 wk of age with hypertrophic pyloric stenosis were reviewed. The infants were treated at the Department of Pediatric Surgery, University of Bern, Switzerland, in the period between 1987 and 1997. A trend towards hypokalaemia (13 of the 139 patients), hypochloraemia (39 patients) and especially metabolic alkalosis (98 patients) was frequently noted on admission. In 84 patients, data on fluid management and on circulating sodium, potassium, chloride and the acid-base balance immediately before surgery were also available. In these patients a significant correlation was found between the parenteral chloride dose given for fluid repair (y = 0.310 x; r = 0.54; p < 0.001) and the changes in plasma bicarbonate. The equation indicates that a chloride dose of 10 mmol/kg body weight is required to reduce plasma bicarbonate on average by 3 mmol/. CONCLUSION: Since assessment of the fluid volume stated by physical examination and history is inaccurate in infants with vomiting, the severity of metabolic alkalosis helps to define the amount of fluid required for repair.     

Inappropriate use of carbamazepine and vigabatrin in typical absence seizures

Carbamazepine and vigabatrin are contraindicated in typical absence seizures. Of 18 consecutive referrals of children with resistant typical absences only, eight were erroneously treated with carbamazepine either as monotherapy or as an add-on. Vigabatrin was also used in the treatment of two children. Frequency of absences increased in four children treated with carbamazepine and two of these developed myoclonic jerks, which resolved on withdrawal of carbamazepine. Absences were aggravated in both cases where vigabatrin was added on to concurrent treatment. Optimal control of the absences was achieved with sodium valproate, lamotrigine, or ethosuximide alone or in combination.     

Localization and quantitation of the vitamin D binding protein (Gc- globulin) in human neutrophils

Plasma-derived vitamin D binding protein (DBP) is an important physiologic regulator of the neutrophil chemotactic response to activated complement. A cell-associated form of DBP has been observed in numerous cell types. We now report that mature, circulating human neutrophils also contain cell-associated DBP. Immunofluorescence studies of normal untreated neutrophils showed the presence of DBP on the cell surface. Western blotting of detergent-soluble neutrophil lysates with a polyclonal anti-DBP showed two major immunoreactive bands, one with an apparent molecular weight of 56 Kd (identical to purified plasma-derived DBP) and a second less prominent band at 12 to 14 Kd. Quantitation of the immunoreactive bands by video densitometry indicated that normal human neutrophils contain 1.5 +/- 0.8 ng DBP/10(6) cells (n = 9). Immunoprecipitation of detergent-soluble lysates with the polyclonal anti-DBP showed only the 56-Kd form by Western blotting. In contrast, a monoclonal anti-DBP immunoprecipitated the 12 to 14 Kd form of DBP from lysates of surface-radioiodinated cells. Western blots of subcellular fractions showed that immunoreactive bands were found in the specific (secondary) granule and plasma-membrane fractions. In addition, pretreatment of neutrophils with 10 nmol/L phorbol myristate acetate (PMA) resulted in approximately a 50% reduction in the amount of DBP in both the specific granule and plasma-membrane fractions. Finally, analysis of the cell- free supernates showed that DBP was spontaneously released into the extracellular milieu: moreover, this release was enhanced if the cells were first stimulated with C5a, formyl-norleucyl-leucyl-phenylalanine (fNLP) or PMA.     

Ring sequestrum: radiographic characteristics of skeletal fixation pin- tract osteomyelitis

Major pin-tract infections are a potentially dangerous complication associated with the use of skeletal transfixation pins. The presence of a characteristic radiographic finding, the ring sequestrum, is virtually diagnostic of this abnormality. The clinical and radiographic findings in seven patients treated for this complication are presented. Thermal necrosis without infection presents as a zone of sclerosis around the tract. A narrow, radiolucent halo may surround the dense bone. When a narrow ring sequestrum is surrounded by a radiolucent halo, there is associated infection.     

Warfarin potentiation with bezafibrate

Two cases are described in which lack of awareness of the potentiation of bezafibrate on warfarin was of clinical importance.     

Peptide-urea interaction

The excess enthalpies of the ternary aqueous solutions containing urea and the glycyl-glycine, glycyl-L-alanine, L-alanyl-L-alanine and sarcosyl-sarcosine diketopiperazines respectively have been determined. A weak but favourable enthalpic contribution to the interaction between these solutes is found. The difference between “strong” and “weak” interactions in aqueous solutions of non-electrolytes is stressed and the role of water in the weak, non-specific interactions, is discussed. The consequence of the weakness of the urea-peptide interactions on the binding of urea to the proteins is also briefly discussed.