Dissecting intermolecular interactions in the condensed phase of ibuprofen and related compounds: the specific role and quantification of hydrogen bonding and dispersion forces.

Ibuprofen is a well-established non-steroidal anti-inflammatory drug, inhibiting the prostaglandin-endoperoxide synthase. One of the key features defining the ibuprofen structure is the doubly intermolecular O-HO[double bond, length as m-dash]C hydrogen bond in cyclic dimers as know from carboxylic acids and confirmed by X-ray analysis. Until now, there was neither information about the vaporization enthalpy of ibuprofen nor about how this thermal property is determined by the subtle balance between different types of intermolecular interaction. In this study we derive the vaporization enthalpy of ibuprofen from thermochemical experiments to be . We dissected the hydrogen bond energy, EHB = 45.0 kJ mol-1, exclusively from measured vaporization enthalpies of related aliphatic carboxylic acids, their homomorph methyl esters and alkyl acetates, respectively. This contribution from hydrogen bonding could be confirmed almost quantitatively from quantum chemical calculations of ibuprofen clusters, which also suggest dispersion interaction of similar order (Edisp = 47 kJ mol-1). Following the full analysis of the gas-vapor transition enthalpy, we studied the changing structural components from the solid to the liquid phase of ibuprofen by means of Attenuated Total Reflection Infrared (ATR-IR) spectroscopy. The cyclic dimers as observed in the X-ray patterns are essentially preserved in the liquid state just above the melting point. However, with increasing temperature the doubly hydrogen-bonded cyclic dimers are replaced by singly hydrogen-bonded linear dimers in the liquid ibuprofen. The transfer enthalpy from the temperature-dependent equilibria of both dimers as obtained from the IR intensity ratios of the vibrational bands quantifies for the first time the energy of the released, single hydrogen bond to be EHB = 21.0 kJ mol-1. Overall, we show that a combination of thermodynamics, infrared spectroscopy and quantum chemistry provides quantification and detailed understanding of structure and molecular interaction in ibuprofen and related compounds.

When hydrogen bonding overcomes Coulomb repulsion: from kinetic to thermodynamic stability of cationic dimers.

Quantum chemical calculations have been employed to study the kinetic and thermodynamic stability of hydroxy-functionalized 1-(3-hydroxyalkyl)pyridinium cationic dimers. For [Py-(CH2)n-OH+]2 structures with n = 2-17 we have calculated the robust local minima with clear dissociation barriers preventing their "Coulomb explosion" into separated cations. For n = 15 hydrogen bonding and dispersion forces fully compensate for the repulsive Coulomb forces between the cations allowing for the quantification of the pure hydrogen bond in the order of 20 kJ mol-1. The increasing kinetic stability even turns to thermodynamic stability with further elongated hydroxyalkyl chains. Now, quantum-type short-range attraction wins over classical long-range electrostatic repulsion resulting in negative binding energies and providing the first thermodynamically stable cationic dimers. The electronic, structural and spectroscopic signatures of the cationic dimers could be correlated to NBO parameters, supporting the existence of anti-electrostatic hydrogen bonds (AEHB) as recently suggested by Weinhold. In principle, these pure cationic dimers should be detectable in gas-phase experiments at low temperatures without the need of mediating molecules or counteranions.

Simultaneous determination of deuteron quadrupole coupling constants and rotational correlation times: the model case of hydrogen bonded ionic liquids.

We show that deuteron quadrupole coupling constants (DQCCs), and reorientational correlation times of molecular bonds N-D that are involved in hydrogen bonding, can be determined from NMR T1 relaxation time experiments simultaneously. For this purpose, we used trialkylammonium-based protic ionic liquids (PILs) as model compounds. They exhibit high viscosities and wide liquid ranges that allow measurements far beyond the extreme narrowing region (ω0τc ≪ 1). The T1 minima already occur at temperatures significantly above room temperature. We obtain reasonable DQCCs for the liquid phase if anisotropic motion is considered. The DQCCs are very small due to attractive Coulomb interaction between the cation and anion, which is further enhanced by hydrogen bonding. The DQCCs strongly depend on the interaction strength of the anion but are independent of the alkyl chain length of the trialkyl ammonium cations pointing to the exclusive cation-anion interaction along the hydrogen bond.

The acceptability of volunteer, repeat blood donations in a hospital setting in the Adamaoua region of Cameroon.

BACKGROUND AND OBJECTIVES: The knowledge of factors that may influence blood donation in Cameroon is limited. The objectives of this study are to assess the characteristics of previous and potential blood donors by exploring the religious beliefs, and knowledge and understanding of blood donations among individuals present at a district hospital. MATERIALS AND METHODS: Forty-nine in-depth, semi-structured interviews were conducted among consenting, randomly selected 18 years or older community members present at a district hospital in the Adamaoua region during October and November 2011. RESULTS: Ninety-eight per cent (48/49) of the individuals present at this district hospital had heard of blood transfusions. Forty-seven per cent (23/49) had not previously been asked to donate blood; however, 94% (44/47) said that they would donate if given the opportunity. Thirty-three per cent (16/49) had previously donated blood to family members or for replacement, and 81% of these said they would repeat donations. The majority of both donors and non-donors were motivated to donate blood for altruistic reasons. CONCLUSION: The findings suggest that community members present at this district hospital in Cameroon may be recruited for repeat blood donations. Although the altruistic motivation to donate blood suggests that donors could be recruited from a district hospital population, targeted information about blood donations and accessible blood transfusion services need to be put in place. The study may add to the understanding of the preconditions for blood donations and the possibility to establish sustainable blood transfusion services in the Adamaoua region in Cameroon.

Self-organizing molecular networks.

Strong diffusional mixing and short delivery times typical for micrometer and sub-micrometer reaction volumes lead to a special situation where the turnover times of individual enzyme molecules become the largest characteristic time scale of the chemical kinetics. Under these conditions, populations of cross-regulating allosteric enzymes form molecular networks that exhibit various kinds of self-organized coherent collective dynamics.

Self-organizing molecular networks.

Strong diffusional mixing and short delivery times typical for micrometer and sub-micrometer reaction volumes lead to a special situation where the turnover times of individual enzyme molecules become the largest characteristic time scale of the chemical kinetics. Under these conditions, populations of cross-regulating allosteric enzymes form molecular networks that exhibit various kinds of self-organized coherent collective dynamics.

Predicting treatment costs and life expectancy for end-stage renal disease.

To estimate the cumulative 10-year direct medical costs and life expectancy associated with different methods of treatment for end-stage renal disease, we assessed predictively three treatment transition options. It is predicted that if 1000 patients shift from facility to home dialysis for each of 10 years, life expectancy of the cohort will not be reduced, but there will be a reduction of $241 million in total costs. The same number shifting from facility dialysis to cadaveric transplantation are predicted to have a $279 to $330 million reduction in total costs but a reduction of 7 to 17 per cent in life expectancy. Shifting from home dialysis to transplantation is predicted to reduce total costs by +103 to $142 million, and life expectancy by 10 to 20 per cent. As new program policies for treatment of end-stage renal disease are developed, their effect on both costs and life expectancy needs to be considered.

Tuberculosis control in a changing health care system: model contract specifications for managed care organizations.

Increasingly, patients with tuberculosis are receiving clinical care in managed care organizations as a result of enrollment in Medicaid or Medicare, or coverage under privately purchased insurance policies or employee benefit plans. This represents a change from the system that has been in place for decades, where the clinical care and public health functions concerning treatment and control of tuberculosis occurred primarily in local health departments. The separation of individual patient care from the public health aspects of tuberculosis control has created challenges for managed care administrators, medical providers, and public health officials. To assist in the integration of the goals of managed care and public health with respect to the prevention and control of tuberculosis, we developed a set of model contract specifications for use by purchasers of managed care and by managed care organizations concerning the management of patients with tuberculosis and other related public health issues. These specifications can assist health officials in continuing their leadership roles by ensuring that managed care contracts address public health needs.

Private sector health care organizations and essential public health services: potential effects on the practice of local public health.

This article focuses on the activities of eight private health care organizations undertaking public health and prevention activities. Few activities were motivated by or integrated into the business or operating strategy of the organizations and poor integration with the business strategy puts the long-term future of these activities in jeopardy. The lack of integrated activity can be attributed to: slow pace of managed care implementation; low penetrance of full-risk capitated reimbursement; and fragmented, competitive health care markets. Purchaser pressure, quality assurance requirements, community benefit standards, and government mandates are among the levers available to encourage such activities by the private sector.

Use of standing orders programs to increase adult vaccination rates.

The Advisory Committee on Immunization Practices recognizes the need for evidence-based policy to improve the delivery and receipt of immunization services recommended for adults (i.e., persons aged > or = 18 years). Two recent, systematic reviews of the health services research literature recommended standing orders programs as an effective organizational intervention to improve vaccination coverage rates among adults. This report briefly reviews the evidence on the effectiveness of standing orders programs, describes standards for program implementation, and recommends initiating these programs to improve immunization coverage in several traditional and nontraditional settings.

[Laparoscopic nephrectomy: report of 2 cases]. / Nefrectomia laparoscópica: comunicación de 2 casos.

Laparoscopic surgery has become very popular in general surgery. Its most significant advantages for patients are a better postoperative comfort and fast return to work. We report two young female patients with a gynecologic cancer in whom a laparoscopic nephrectomy was performed. The surgical procedure and the post operative recovery were uneventful. These promising results show that laparoscopic surgery is applicable in traditional urologic procedures.

Prostatectomía radical laparoscópica: experiencia inicial / Laparoscopic radical prostatectomy: initial experience

La prostatectomía radical es el tratamiento de elección en tumores confinados a la glándula. Desde las publicaciones de Guilleneau y Vallancien, el abordaje laparoscópico ha sido un tema de controversia. Entre mayo de 2000 y abril de 2001 se seleccionaron 18 pacientes para prostatectomía radical laparoscópica. Todos los pacientes eran portadores de un adenocarcinoma prostático localizado, en estadíos clínicos T1 y T2. La edad promedio fue de 65 años y el estadío clínico fue <= T2a. El APE promedio fue de 11 ng/ml y el score de Gleason estuvo entre 5 y 8. El tiempo operatorio fue en promedio de 260 minutos (rango de 155 a 450 minutos). El sangrado promedio fue de 344 ml. Fue necesaria la conversión en 2 de los primeros pacientes. La complicación más frecuente fue la lesión de recto en 3 pacientes, reconocida intraoperatoriamente. Nos encontramos en el inicio de la curva de aprendizaje de la técnica, por lo que se deberá esperar una serie mayor de pacientes para poder realizar conclusiones más acertadas.