Extracting covalent and ionic structures from usual delocalized wave functions: the electron-expansion methodology.

We present easily programmable expansions, allowing the calculation of the weights of local covalent and ionic structures of a chemical bond from usual delocalized wave functions; they are obtained in the framework of the electron-expansion methodology, in which the hole conditions (involved by definition in a covalent or ionic structure) are expanded in terms involving only electrons. From the derived relations, true for both HF and correlated levels, one can also express the covalency/ionicity and the localization of a usual two-electron two-center (2e/2c) bond in terms of electronic populations. The three-electron populations are crucial for bond localization. On the contrary, in 2e/2c bonding, and particularly in Charge-Shift bonds (which show enhanced covalent-ionic interactions) although the three-electron populations can be non-negligible, they are not important for the covalency/ionicity of these bonds. Numerical applications and discussion are given for correlated MO wave functions of butadiene, hexatriene, and pyrrole molecules on the basis of both natural atomic orbitals (NAOs) (orthogonal orbitals) and pre-NAOs (nonorthogonal orbitals).

Anticonvulsants for alcohol withdrawal.

BACKGROUND: Alcohol withdrawal syndrome is a cluster of symptoms that occurs in alcohol-dependent people after cessation or reduction in alcohol use. This systematic review focuses on the evidence of anticonvulsants' use in the treatment of alcohol withdrawal symptoms. OBJECTIVES: To evaluate the effectiveness and safety of anticonvulsants in the treatment of alcohol withdrawal. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2004); MEDLINE (1966 to October 2004); EMBASE (1988 to October 2004) and EU-PSI PSI-Tri database with no language and publication restrictions and references of articles. SELECTION CRITERIA: All randomized controlled trials examining the effectiveness, safety and overall risk-benefit of an anticonvulsant in comparison with a placebo or other pharmacological treatment or another anticonvulsant were considered. DATA COLLECTION AND ANALYSIS: The authors independently assessed trial quality extracted data. MAIN RESULTS: Forty-eight studies, involving 3610 people were included. Despite the considerable number of randomized controlled trials, there was a variety of outcomes and of different rating scales that led to a limited quantitative synthesis of data. For the anticonvulsant versus placebo comparison, therapeutic success tended to be more common among the anticonvulsant-treated patients (relative risk (RR) 1.32; 95% confidence interval (CI) 0.92 to 1.91), and anticonvulsant tended to show a protective benefit against seizures (RR 0.57; 95% CI 0.27 to 1.19), but no effect reached formal statistical significance. For the anticonvulsant versus other drug comparison, CIWA-Ar score showed non-significant differences for the anticonvulsants compared to the other drugs at the end of treatment (weighted mean difference (WMD) -0.73; 95% CI -1.76 to 0.31). For the subgroup analysis of carbamazepine versus benzodiazepine, a statistically significant protective effect was found for the anticonvulsant (WMD -1.04; 95% CI -1.89 to -0.20), p = 0.02), but this was based on only 260 randomized participants. There was a non-significant decreased incidence of seizures (RR 0.50; 95% CI 0.18 to 1.34) favouring the patients that were treated with anticonvulsants than other drugs, and side-effects tended to be less common in the anticonvulsant-group (RR 0.56; 95% CI 0.31 to 1.02). AUTHORS' CONCLUSIONS: It is not possible to draw definite conclusions about the effectiveness and safety of anticonvulsants in alcohol withdrawal, because of the heterogeneity of the trials both in interventions and the assessment of outcomes. The extremely small mortality rate in all these studies is reassuring, but data on other safety outcomes are sparse and fragmented.

Pain experience following radical treatment for head and neck cancer.

During an investigation into the quality of life of people in the year following radical treatment for head and neck cancer, it became apparent that pain was a significant problem. Therefore, the current study was conducted to gain an understanding of the incidence and nature of pain in people who had received radical treatment for head and neck cancer and to explore their attitudes to pain and pain relief. A single cohort study was undertaken using a structured questionnaire designed for people with head and neck cancer (the EORTC QLQ-C30 and the EORTC QLQ H+N35). Fifty questionnaires were received from people who had received radical treatment between 6 and 12 months previously and who were disease-free. Twenty nine of the respondents also consented to a follow-up semi-structured interview. The interviews generated qualitative data about personal experiences of pain and pain management in head and neck cancer. Patient recollections from interviews identified that only nine out of 29 (31%) interviewees had pain at diagnosis. However, 74% (37) of respondents to the questionnaire reported some degree of pain at follow-up. Patients having both surgery and radiotherapy were significantly more likely to have troublesome pain than patients who received radiotherapy only (Fisher's exact test=0.039). The qualitative data identified a wide variety of pain sites, a number of which were not covered by the EORTC tool. A significant number of patients were rejecting regular pharmacological management and using a variety of other pain-relieving measures. We conclude that through an understanding of pain experience and attitudes to pain management, nurses can facilitate the care and support of patients in pain following treatment for head and neck cancer.

Prioritizing investments in health technology assessment. Can we assess potential value for money?

OBJECTIVE: The objective was to develop an economic prioritization model to assist those involved in the selection and prioritization of health technology assessment topics and commissioning of HTA projects. METHODS: The model used decision analytic techniques to estimate the expected costs and benefits of the health care interventions that were the focus of the HTA question(s) considered by the NHS Health Technology Assessment Programme in England. Initial estimation of the value for money of HTA was conducted for several topics considered in 1997 and 1998. RESULTS: The results indicate that, using information routinely available in the literature and from the vignettes, it was not possible to estimate the absolute value of HTA with any certainty for this stage of the prioritization process. Overall, the results were uncertain for 65% of the HTA questions or topics analyzed. The relative costs of the interventions or technologies compared to existing costs of care and likely levels of utilization were critical factors in most of the analyses. The probability that the technology was effective with the HTA and the impact of the HTA on utilization rates were also key determinants of expected costs and benefits. CONCLUSIONS: The main conclusion was that it is feasible to conduct ex ante assessments of the value for money of HTA for specific topics. However, substantial work is required to ensure that the methods used are valid, reliable, consistent, and an efficient use of valuable research time.

An empirical investigation of pressure ulcer risk factors.

Despite many improvements in practice, pressure ulcers continue to be a source of concern to nurses and distress to patients. Clearly, there are no simple solutions to this problem and it is necessary to improve our understanding of pressure ulcer epidemiology and the effectiveness of preventive methods to continue to progress. Risk assessment is an important aspect of such work and forms the topic of this article. The authors first consider some of the difficulties associated with risk assessment and suggest that progress requires the use of multivariate statistical methods. They then describe the difficulty of comparing existing studies, which gives rise to the need for further work. A description of the study currently being undertaken follows, together with a presentation of the preliminary findings and a discussion of their implications for practice.

Ruptured aneurysm at the trunk of the accessory middle cerebral artery.

We present a 32-year-old woman with intracranial haemorrhage due to rupture of a saccular aneurysm arising from the trunk of an accessory middle cerebral artery. This is the first report of an aneurysm arising distally to the anomalous vessel's origin from the A1 segment of the anterior cerebral artery.