Structure and phase transitions of monolayers of intermediate-length n-alkanes on graphite studied by neutron diffraction and molecular dynamics simulation.

We present evidence from neutron diffraction measurements and molecular dynamics (MD) simulations of three different monolayer phases of the intermediate-length alkanes tetracosane (n-C(24)H(50) denoted as C24) and dotriacontane (n-C(32)H(66) denoted as C32) adsorbed on a graphite basal-plane surface. Our measurements indicate that the two monolayer films differ principally in the transition temperatures between phases. At the lowest temperatures, both C24 and C32 form a crystalline monolayer phase with a rectangular-centered (RC) structure. The two sublattices of the RC structure each consists of parallel rows of molecules in their all-trans conformation aligned with their long axis parallel to the surface and forming so-called lamellas of width approximately equal to the all-trans length of the molecule. The RC structure is uniaxially commensurate with the graphite surface in its [110] direction such that the distance between molecular rows in a lamella is 4.26 A=sqrt[3a(g)], where a(g)=2.46 A is the lattice constant of the graphite basal plane. Molecules in adjacent rows of a lamella alternate in orientation between the carbon skeletal plane being parallel and perpendicular to the graphite surface. Upon heating, the crystalline monolayers transform to a "smectic" phase in which the inter-row spacing within a lamella expands by approximately 10% and the molecules are predominantly oriented with the carbon skeletal plane parallel to the graphite surface. In the smectic phase, the MD simulations show evidence of broadening of the lamella boundaries as a result of molecules diffusing parallel to their long axis. At still higher temperatures, they indicate that the introduction of gauche defects into the alkane chains drives a melting transition to a monolayer fluid phase as reported previously.

Immunomodulation by perioperative administration of n-3 fatty acids.

It has been increasingly reported that administration of n-3 fatty acids is beneficial in patients with inflammatory processes. This effect is most likely caused by different biological characteristics, including an immunomodulating effect of the products derived from n-3 fatty acids through eicosanoid metabolism. The aim of this study was to investigate the effect of perioperative administration of n-3 fatty acids on inflammatory and immune responses as well as on the postoperative course of patients with extended surgical interventions of the abdomen. In particular, the effect of n-3 fatty acids on interleukin-6 release and on granulocyte/monocyte function (HLA-DR expression) was studied. There was a downregulation of the inflammatory response, and, simultaneously, a smaller postoperative immune suppression in the n-3 fatty acid group. In addition, we observed shorter postoperative periods in the intensive care unit and on the regular medical wards as well as lower rates of severe infections. The results suggest that perioperative administration of n-3 fatty acids may have a favourable effect on outcome in patients with severe surgical interventions by lowering the magnitude of inflammatory response and by modulating the immune response.

[Interleukin pattern, procalcitonin level and cellular immune status after endovascular aneurysm surgery]. / Interleukinmuster, Procalcitoninspiegel und zellulärer Immunstatus nach endovaskulärer Aneurysmachirurgie.

Endovascular repair of AAA's using stent grafts is considered to be a minimally invasive procedure. However, in some cases deleterious inflammatory reactions, e.g., flu-like postinterventional symptoms are observed. A few patients even develop a fatal "postimplantation syndrome". It is not clear whether these postoperative complications result from a) the inflammatory and immune response to the inserted graft material, b) alterations of the vascular endothelium during the implantation procedure, c) residual thrombotic material, or d) a combination of all these causes. This clinical trial aimed to prospectively investigate the association between inflammatory mediators like interleukin-1 receptor antagonist (IL-1RA), IL-6, and HLA-DR expression on monocytes and clinical outcome in patients after repair of abdominal aortic aneurysms (AAA). Fifteen patients treated with endovascular stent grafts for abdominal aortic aneurysm (AAA-E) were compared with 15 selected control patients who underwent a conventional surgical procedure (AAA-K) during the same period. Prior to intervention, there were no significant differences in marker levels. One hour postoperatively, IL-6 (421 pg/ml vs. 21 pg/ml) and IL-1RA (10,061 pg/ml versus 407 pg/ml) were significantly increased in the AAA-K-group, whereas in AAA-E patients, these parameters increased more gradually during the first postoperative day and did not reach the same level as in the control group. There was only a slight reduction of HLA-DR expression in both groups compared with baseline and no signs indicating a postimplantation syndrome were found. No excessive inflammatory response or complicated final outcome were observed. It is unclear if this can be explained by the prophylactic use of indometacin.

[Heparin-induced thrombocytopenia type II: reexposure to heparin]. / Heparin-induzierte Thrombozytopenie Typ II: Re-Exposition mit Heparin.

HISTORY AND ADMISSION FINDINGS: At the age of 55 years a now 70-year-old man had his aortic valve replaced by a prosthetic (Björk-Shiley) valve, and 11 years later a VDD pacemaker had been implanted. 18 months before the latest admission he had been hospitalized for treatment of staphylococcal endocarditis involving the aortic prothesis. At that time thrombocytopenia developed during heparin administration, diagnosed clinically and with the heparin-induced platelet activity (HIPA) test as type II heparin induced thrombocytopenia. His latest admission was for the diagnosis and treatment of peripheral arterial disease of the right leg (Fontaine stage IIb). INVESTIGATIONS: Right popliteal and pedal pulses were not palpable. He was able to walk pain-free for only 70 m. Doppler sonography demonstrated an arm-leg index on the right of 0.7. Angiography revealed marked stenosis in the right superficial femoral artery and a filiform stenosis in the right popliteal artery. TREATMENT AND COURSE: Both stenoses were relieved by percutaneous transluminal balloon angioplasty, in the course of which 5000 IU heparin were administered as a bolus intraarterially. Postoperative anticoagulation was maintained for 2 days with recombinant hirudin. There was no evidence of platelet reduction or heparin-induced antibodies despite the renewed infusion of heparin. CONCLUSION: Single re-administration of heparin in a patient who had developed a type II heparin-induced thrombocytopenia several years before does not necessarily lead to a booster of antibodies and thus to a reduction of platelets in the peripheral blood. It is a moot point whether the course in this case was an exception or the rule.

Accuracy of frozen section measurements for the determination of Breslow tumour thickness in primary malignant melanoma.

AIMS: Microstaging of primary malignant melanoma (MM) and the width of surgical margins depend mainly on Breslow tumour thickness (BTT). The use of frozen section (FS) measurements of BTT has been doubted, and previous reports have shown conflicting results regarding the comparability to paraffin sections (PS). To look for significant differences of BTT due to freezing or paraffin embedding, we evaluated a larger series of melanocytic lesions as far as possible excluding other technical influences. METHODS AND RESULTS: Paired 'mirror sections' of 112 melanocytic lesions (33 MM and 79 melanocytic naevi) were measured according to Breslow on single corresponding PS and FS of the same tumour specimen. Comparing measurements on FS and PS, we found very small differences of BTT on average and an almost equal distribution of BTT in the two sets of values with no statistically significant difference by applying the Wilcoxon signed rank test. Concerning the clinically most important 1 mm-threshold of BTT, 110 (98.2%) of the lesions gave equal measurements in FS and PS. CONCLUSIONS: Frozen sections can be used for accurate measurements of Breslow tumour thickness. Consequently, intraoperative frozen section diagnosis of thick melanoma immediately followed by excision with wide surgical margins is possible in experienced centres.

Methylphenidate effect on attention deficit in the acutely brain-injured adult.

OBJECTIVES: To determine the efficacy of methylphenidate in improving attention and functional outcome in acutely brain-injured adults. DESIGN: Prospective multiple baseline design (A-A-B-A) utilized on a consecutive sample of patients. SETTING: Acute brain injury rehabilitation unit in a large academic medical center. PATIENTS: Eleven acutely brain-injured adults were included by performing below two standard deviations of the age equivalent norms on 4 of 5 neuropsychological tests for attentional capacity. One subject was withdrawn after developing tachycardia. INTERVENTION: After a 1-week baseline assessment, subjects were placed on increasing doses of methylphenidate (Ritalin) so that on Day 7 all patients received a dose of 15 mg at 8 am and 12 pm. MAIN OUTCOME MEASURES: Nine neuropsychological subtests measured attention on admission, at 1 week, while on methylphenidate, and 1 week after its discontinuation. Functional outcome was evaluated utilizing the Disability Rating Scale (DRS) at the same intervals. RESULTS: Digit Span, Mental Control, and Symbol Search scores improved significantly (p < .05) on methylphenidate (A-B) as compared with the pre-methylphenidate (A-A) period. This advantage remained when the drug was removed. The mean improvement in DRS scores on methylphenidate approached a significant difference (p < .06) from that change in the DRS scores between baseline 1 and 2. CONCLUSIONS: Use of methylphenidate in acutely brain-injured adults was well tolerated and demonstrated a significant improvement in attention compared to natural recovery in a rehabilitation setting. Methylphenidate also correlated with faster functional recovery as measured by the Disability Rating Scale although the improvement did not achieve statistical significance.

Effects of partial decortication on opioid analgesia in the formalin test.

Partially decorticated rats were tested for their response to nociceptive stimulation in the formalin and tail flick tests, and for the effect of morphine on these responses and on motor activity. Undrugged rats showed vigorous responses to nociceptive stimulation in both tests, and exhibited the typical biphasic time course of pain in the formalin test. Morphine 4 and 8 mg/kg produced dose-dependent analgesia in both tests in sham operated rats, and in rats with lesions that removed all or part of the cortex from the midline to the rhinal fissure (excluding the occipital cortex). In rats with lesions that extended deep into the piriform cortex and damaged the amygdala morphine analgesia was eliminated or attenuated. These and other recent findings suggest that analgesia in the formalin test depends on ascending connections to the forebrain, probably the amygdala.

Behavioral management of agitation in the traumatically brain-injured person.

This paper outlines general management strategies used to prevent and control agitation throughout the continuum of recovery from traumatic brain injury. These include environmental management, alterations in the behavior of staff and family, use of physical and chemical restraints, redirection and substitution, time out, operant procedures, self monitoring and relaxation training. The need for both flexibility in choice of strategies and consistency in application is emphasized, along with the importance of staff training and patient and family participation.

Evidence to support the influence of the nucleus accumbens on drug-induced psychopathology

This study was designed to evaluate the hypothesis that the mesolimbic dopamine pathways are involved in the manifestations of psychotic symptoms. Rats were injected with amphetamine (5.0 mg/kg) and apomorphine (1.0 mg/kg) following bilateral lesions of the nucleus accumbens. The results showed high levels of stereotypy following amphetamine administrations in contrast to the low levels seen after the administration of apomorphine. These results, in conjunction with previous experiments involving the globus pallidus, were evaluated in terms of the accumbens' influence on drug-induced psychosis (AU)

Common psychological illnesses in the elderly

The elderly are especially prone to psychological illness. Cognitive impairment increases with age and as this is a primary symptom of many common disorders, it constitutes a major health problem. The elderly also frequently become depressed and have the highest suicide rate of all age groups. Given the increasing numbers of elderly persons in the population, the primary care physician must assume the reponsibility of evaluating, diagnosing and initiating psychiatric treatment with an emphasis on early and accurate diagnosis, and the detection of underlying causes, many of which are reversible (AU)