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A 31 year old man was admitted with recurrent syncope. Questions (1) Describe the abnormal features on his 12 lead electrocardiogram (fig 1). (2) What is the diagnosis and what [...]

The photoinduced dynamics of thiophene and 2,5-dimethylthiophene (2,5-DMT) were investigated upon excitation at 200 and 255 nm (2,5-DMT only) using time-resolved photoelectron spectroscopy and compared with results from ab initio coupled cluster calculations. For thiophene, depopulation of the initially excited B2(π3π4*) state to the lower-lying A1(π2π4*) state occurs within 25 ± 20 fs, with a subsequent bifurcation into a ring-puckering channel and a ring-opening channel with lifetimes of 80 ± 20 and 450 ± 50 fs, respectively. For 2,5-DMT, the dynamics following excitation at 200 nm is described by a monoexponential decay with a time constant of 120 ± 20 fs, while that following excitation at 255 nm is best fit by a biexponential decay with time constants of 115 ± 20 fs and 15 ± 3 ps, respectively. The fast signal observed after excitation of 2,5-DMT is assigned to the ring-opening channel, which is favored with respect to thiophene due to a lower excited-state barrier along the ring-opening coordinate and an increased inertia toward the ring-puckering channel. Coupled cluster calculations have been undertaken to compare the relaxation dynamics of thiophene to thiazole and isothiazole. For the latter two molecules, we find a strong gradient along the ring-opening coordinate in the Franck–Condon region of the initially populated ππ* state and predict that ring-opening is the dominating relaxation channel after photoexcitation. We use the extracted information for a comparison of the thiophene dynamics with the light-induced processes observed in other five-membered heterocyclic molecules.

In this paper, we report results regarding how LiH2+ fragments as a result of a low-energy collision with an electron (dissociative recombination), a reaction that contains only elements and particles created during the very first phase of the universe. The collision-energy-dependent reaction rate and cross sections show detailed structures, more so than predicted by theory, suggesting significant rovibrational coupling in the ion and a complex reaction surface. From the structure of the molecule, the reaction predominantly results in the formation of Li + H2. However, 23% of the reaction flux leads to more interesting products, with 17% producing Li + 2H and 6% producing LiH + H. These last two channels break the strongest molecular bond in the system and, in the case of the latter channel, form a significantly weaker ionic bond. Possible reasons behind this interesting behavior are discussed, together with the interaction between the available reaction channels. [ABSTRACT FROM AUTHOR]

Cross sections and branching ratios are presented for the dissociative recombination of the CF+2and CF+3ions with electrons. It is found that the channel producing CF + F is dominant for the reaction with CF+2and the production of CF2+ F is dominant for the reaction with CF+3. The cross sections for these two ions are very similar.

Absolute cross sections for electron-impact dissociation of D13CO+ions have been measured over a collision energy range from 4 to 100 eV with a crossed electron-ion beams method. Total experimental uncertainties are about 16% near the cross section peak. The role of resonant and direct dissociative excitation for energies below 21 eV is discussed in light of the energy levels and photo-dissociation cross sections of the HCO+formyl cation predicted by ab initiomulti-reference configuration interaction calculations.

The dissociative recombination and excitation of CF+have been measured at the ASTRID and CRYRING storage rings. Though examination of the available potential energy curves would suggest that the recombination rate would be large for this ion, in fact a rate constant of 5.2 ± 1.0 × 10?8(Te/300)?0.8cm3s?1was found. The recombination cross section at low energies falls off to a minimum at 0.5 eV centre-of-mass collision energy but exhibits resonances at energies above this. The dissociative excitation cross section leading to C++ F was also measured and this displays an onset beginning at about 7 eV.

We have investigated the dissociative recombination of the N2Oion using the CRYRING heavy-ion storage ring at the Manne Siegbahn laboratory in Stockholm, Sweden. The dissociative recombination branching ratios were determined at minimal 0 eV collision energy, showing that the dominating pathways involved two-body fragmentation: N2 O 48 and NO N 36. The branching ratio of the three-body break-up 2N O was 16. The overall thermal rate coefficient of the title reaction follows the expression kT 3.34 ± 0.75 × 10−7T300−0.57±0.03cm3s−1, which correlates perfectly with earlier flowing afterglow studies on the same process.

There has been a definite increase in the popularity and use of complementary and alternative medicines, including herbal medicines, in the last ten years. The aim of this study was to determine the prevalence and patterns of use of herbal medicines and vitamin supplements by patients in the preoperative period. A questionnaire was offered to all patients attending the pre-admission clinics at St. Vincent's Hospital and Box Hill Hospital, Melbourne, over an eight-month period in 2002.In all, 1102 questionnaires were completed (91.8% response rate). The prevalence of herbal medicine use was 14.3%, with an average user age of 54.0 years and 61.4% female predominance. The five most popular herbs were Garlic, Evening Primrose, Gingko, St. John's Wort and Echinacea. The commonest reasons for herbal medicine use were acute and chronic medical conditions. 63.2% of patients had self-prescribed. 27.8% of herbal remedy users had informed the hospital doctors and 41.8% had notified their general practitioner. The prevalence of vitamin supplement use was 20.4%, with an average user age of 54.8 years and 66.2% female predominance. The five most popular vitamins were multivitamins, followed by vitamin B, C, E and D. The commonest reasons for vitamin use were maintenance of general well-being and health.The use of herbal medicines and vitamin supplements preoperatively by patients is common. Clinicians should endeavour to familiarize themselves with the more popular and significant herbal medications and, as part of the routine preoperative assessment, ask all their patients about their consumption of herbal remedies.

We have tested the hypothesis that the meniscofemoral ligaments make a significant contribution to resisting anteroposterior and rotatory laxity of the posterior-cruciate-ligament-deficient knee. Eight cadaver human knees were tested for anteroposterior and rotatory laxity in a materials-testing machine. The posterior cruciate ligament (PCL) was then divided, followed by division of the meniscofemoral ligaments (MFLs). Laxity results were obtained for intact, PCL-deficient, and PCL-MFL-deficient knees.Division of the MFLs in the PCL-deficient knee increased posterior laxity between 15° and 90° of flexion. Force-displacement measurements showed that the MFLs contributed 28% to the total force resisting posterior drawer at 90° of flexion in the intact knee, and 70.1% in the PCL-deficient knee. There was no effect on rotatory laxity.This is the first study which shows a function for the MFLs as secondary restraints to posterior tibial translation. The integrity of these structures should be assessed during both imaging and arthroscopic studies of PCL-injured knees since this may affect the diagnosis and management of such injuries.

The meniscofemoral ligaments were studied in 84 fresh-frozen knees from 49 cadavers. Combined anterior and posterior approaches were used to identify the ligaments. In total, 78 specimens (93%) contained at least one meniscofemoral ligament. The anterior meniscofemoral ligament (aMFL) was present in 62 specimens (74%), and the posterior meniscofemoral ligament (pMFL) in 58 (69%). The 42 specimens (50%) in which both ligaments were present were from a significantly younger population than that with one MFL or none (p < 0.05). Several anatomical variations were identified, including oblique fibres of the posterior cruciate ligament (PCL), which were seen in 16 specimens (19%). These were termed the ‘false pMFL’.The high incidence of MFLs and their anatomical variations should be borne in mind during arthroscopic and radiological examination of the PCL. It is important to recognise the oblique fibres of the PCL on MRI in order to avoid wrongly identifying them as either a pMFL or a tear of the lateral meniscus. The increased incidence of MFLs in younger donors suggests that they degenerate with age.

In this study we investigated the effect of topical application of cool irrigation fluid on brain tissue temperature during craniotomy.Eight patients were given a standard general anaesthetic for craniotomy. Distal oesophageal and nasopharyngeal temperatures were measured continuously and systemic normothermia was maintained. A sterile needle temperature probe was inserted 18 mm into the cerebrum to measure brain temperature. Brain temperatures were recorded for five minutes while the brain was irrigated with 1000 ml of normal saline at a temperature of 30°C. Measurement continued until the brain temperature returned to baseline.The mean maximum decrease in cerebral parenchymal temperature following irrigation was 1.6±0.5°C (P<0.01). The average time to return to baseline temperature after cessation of irrigation was 5.3±1.5 minutes.Cooling the brain has a marked protective effect after brain injury, but systemic hypothermia can produce significant harmful effects. This study demonstrates that the use of cool irrigation fluid during neurosurgery is a simple and effective method of cooling the brain whilst minimizing the use of systemic hypothermia.

OBJECTIVES: To study the safety and benefit of mitral balloon valvotomy (MBV) in patients aged ≥ 80 years.

The local fibrinolytic activity of the femoral, popliteal and soleal veins has been studied using a histochemical technique. The results suggest that the fibrinolytic activity in the soleal veins may be low when compared with that in the femoral and popliteal veins. This may be an aetiological factor responsible for the high incidence of thrombi occurring in the soleal veins.

The effect of verapamil 120 mg t.d.s. was compared with propranolol 160 mg b.d. in the treatment of stable angina pectoris. Nineteen patients were studied in a randomized, double-blind, crossover trial, using patient diaries, exercise-testing and ambulatory electrocardiographic monitoring. Both drugs were given for 1 month. On average the number of attacks of angina was reduced equally by verapamil and propranolol. The degree of electrocardiographic evidence of myocardial ischaemia was decreased by the same amount, but verapamil was significantly more effective in prolonging the exercise time. Both drugs reduced the number of episodes of ST-segment depression during 24 hours of ambulatory electrocardiographic monitoring, which was analyzed in nine patients. It is concluded that verapamil compares very favourably with propranolol in the treatment of stable angina, and is more beneficial in improving exercise capacity.

1. The amount of lean tissue in the body can be assessed by measuring total body nitrogen, total body potassium or fat-free mass. To compare these techniques we have measured total body nitrogen, total body potassium and fat-free mass in 91 healthy subjects (62 males, 29 females). 2. Total body nitrogen in the women and civilian men agreed closely with the few values reported previously and was closely related to total body potassium and fat-free mass. 3. The simplest estimate of total body nitrogen in a subject whose body content has not been measured is the mean value for healthy people of the same sex. The standard deviation of individual values about this mean is 253 g. The precision of the estimate can be improved considerably by predicting body nitrogen from fat-free mass (156 g) and somewhat more by predicting it from body potassium (115 g). The error of measuring total body nitrogen directly is approximately 76 g. 4. When an individual's total body potassium is measured in a search for potassium depletion, the observed value must be compared with the value expected if the subject were healthy. The standard deviation of the healthy values about the group means is 408 mmol. The precision of the estimate can be improved by predicting total body potassium from fat-free mass (sd 237 mmol), and rather more by predicting it from total body nitrogen (sd 186 mmol). If gross body composition is normal, measurement of total body nitrogen has little advantage over measurement of fat-free mass by the anthropometric technique. 5. These results suggest that the simpler measure of fat-free mass from body weight and skinfold thickness has a major role in the assessment of total body nitrogen, and thus lean body tissue, in the individual.

1. The effects of single oral doses of various sympatholytic drugs on the heart rate and blood pressure increases during isometric handgrip contraction were studied in six healthy subjects. 2. Bethanidine reduced both the systolic and diastolic increases in pressure. Clonidine reduced the systolic but not the diastolic increase. Oxprenolol alone or in combination with phentolamine or phenyoxybenzamine failed to influence the pressor response. 3. The increase in systemic blood pressure associated with sustained contraction of voluntary muscle appears to be relatively resistant to acute sympathetic adrenoreceptor blockade in man.

Anna Comnena’s history the Alexiadhas been accorded a high honorary status by Byzantine historians. Her pioneering efforts in philosophy and the thoroughness of her historical methodology are admired, although there is a distinct reluctance to analyse her historical writing. On a superficial level the Alexiadis a straightforward text: an historical panegyric in its organisation, frequently eulogistic in tone, in the manner of court orations, and rhetorically strongly influenced by conventional Byzantine pastiches of Homer.

Ether cleavage of THF at low temperature affords halide-free neohexyllithium in a two-step reaction via insertion of in situ formed ethylene into the C-Li bond of tert-butyllithium. The crystal structure analysis reveals the formation of tetrameric THF-solvated aggregates in the solid state. The neohexyl ligands adopt a staggered arrangement with respect to the tetrahedral lithium core, in contrast to the eclipsed conformation generally observed in unsolvated species. The different conformations in these oligomers can be rationalized readily by distinguishing between primary and secondary cation coordination.

1. Sodium and potassium transport rates in human leucocytes were measured in vitro at different external potassium concentrations. 2. At nominally zero external potassium concentrations, the ouabain-sensitive sodium efflux was reduced to less than 20% of its maximum value. There was evidence that under these conditions a ouabain-sensitive sodium-sodium exchange occurs. 3. Both total and ouabain-insensitive potassium influx increased with increasing external potassium concentration. The ouabain-sensitive potassium influx showed saturation. 4. Ouabain-insensitive potassium efflux was also stimulated by increasing the external potassium concentration, suggesting significant potassium-potassium exchange at physiological external potassium concentrations.

1. In sixteen patients with severe chronic renal failure the rate constant for total sodium efflux from leucocytes was significantly reduced compared with that in thirty control subjects. This difference lay chiefly in the glycoside-sensitive (‘active’) moiety of sodium efflux. 2. In sixteen patients receiving regular haemodialysis, the rate constant for total sodium efflux from the leucocyte was significantly greater than in the undialysed uraemic patients though still subnormal. 3. In individual patients, an increase in sodium efflux could be detected as early as 1 week after regular haemodialysis was started. 4. These results are compatible with the existence of a dialysable molecule in uraemic plasma affecting leucocyte sodium transport.

Abstract: Objective. Unusual manifestations are occasionally encountered in Langerhans cell histiocytosis and may be a source of confusion. The objective of this study was to determine the frequency of occurrence of the unusual manifestations in our case material. Design and patients. Thirty-four children, average age 4.4 years (range 3 months to 16 years) with 262 skeletal lesions of biopsy-proven Langerhans cell histiocytosis (LCH) were retrospectively reviewed to determine the frequency of occurrence of unusual manifestations defined either as an atypical location of a skeletal lesion or an atypical radiographic appearance of the lesion. Results. Twenty-four unusual lesions were found in this retrospective review. Among these were epiphyseal lesions, transphyseal lesions, extracranial ’button’ sequestra, posterior vertebral arch lesions, dural extension of vertebral lesions, and fluid-fluid levels. The finding of fluid-fluid levels has not previously been described in the radiologic literature. Involvement of unusual sites included clavicles and small bones of the hands and feet. Conclusions. Radiographic, computed tomographic, and magnetic resonance imaging of LCH yield a variety of unusual manifestations. Recognition of these varied appearances of LCH may prevent confusion of such appearances with other pathologic processes. When the unusual manifestation occurs as the initial finding of the disease, LCH should be included in the differential diagnosis.

Amino acids esterified to the ribose group of 5'-adenylic acid (AMP) constantly migrate between the 2' and 3' positions of the ribose at a rate of several times per second, which is slower than the rate of peptide-bond synthesis (15-20 per sec). Because the contemporary protein-synthesizing system only incorporates amino acids into protein when they are at the 3' position of the AMP at the terminus of tRNA, the value of the equilibrium constant relative to the 2' and 3' positions is of considerable interest. Differences between D and L isomers in this regard might be especially revealing. We have used N-acetylaminoacyl esters of AMP as models for the 3' terminus of tRNA and find that glycine and the L amino acids consistently distribute predominantly to the 3' position (approximately equal to 67% 3', approximately equal to 33% 2'), but D amino acids distribute to that position generally to a lesser extent and in a manner inversely related to the hydrophobicity of the amino acid side chain. This consistency of the L amino acid preference for the 3' position, combined with the inconsistency of the D amino acid preference, may be one reason for the origin of our contemporary protein-synthesizing system, which forms the peptide bond preferentially with L amino acids and only when they are in the 3' position of the ribose moiety of the AMP residue at the 3' terminus of every tRNA.

Two hundred and nine patients with moderate to severe chronic heart failure, all of whom remained symptomatic despite at least 80 mg of frusemide daily, were randomized to 12 months treatment with flosequinan or captopril. The patients were stratified into two groups, a treadmill group and a corridor walk test group, depending upon their exercise capability. Sixty-five out of 102 patients randomized to flosequinan and 43 out of 107 randomized to captopril (p<0.001) did not complete the study. There was no difference between the groups in mortality: 19 patients died while taking flosequinan and 15 while taking captopril. Both drugs had similar effects on treadmill exercise tolerance; the mean increase at week 52 was 117 seconds in the flosequinan group and 156 seconds (p=0.57) for the captopril group. For those patients stratified to the corridor walk test only, there was also very little difference in the improvement at 52 weeks; the mean increase for patients randomized to flosequinan was 61 meters and captopril was 75 meters (p=0.65). However, when the walk tests from all patients are examined, captopril produced a significant improvement compared with flosequinan at week 52 (p=0.015). Flosequinan has similar long-term efficacy to captopril but is associated with a higher incidence of adverse events.

The bimolecular rate coefficients and ion products for the reactions of H3O⁺ and H2O⁺ with the bromine-containing molecules CF3Br, CF2Br2, CF2BrCl, CFBr3, CFBr2Cl, and CBrCl3 at 300 K are reported. With the exception of the reactions of H3O⁺ with CF3Br and CF2BrCl, the rate coefficients are near the collisional values (k ≈ 10^-9 cm³ molecule^-1 s^-1). The most efficient exit pathway for the majority of the H3O⁺ reactions is the formation of a trihalomethyl cation, together with water and a hydrogen halide as the neutral products. In each case, more than one trihalomethyl cation can be formed. The branching ratios are largest for the products resulting from the breaking of a C−F bond. This is attributed to the high bond strength of HF relative to HCl and HBr. Similarly for CBrCl3, the major product cation is CCl2Br⁺. The H2O⁺ reactions are found to proceed predominantly via charge transfer. For the reaction of H2O⁺ with CF3Br there is clear evidence for intimate reaction pathways in which bonds are broken and formed.

In a 12-month prospective survey of CPR (cardiopulmonary resuscitation), 32 out of 192 patients (16.6%) survived to go home. This is a clear improvement compared with 7 years previously. This is attributed to better training in the use and management of CPR and more widespread availability of defibrillators. Certain patients could not be resuscitated--those with electromechanical dissociation, carcinoma, or multiple pathology. Age by itself was not a bar to resuscitation. There is still a high rate of inappropriate calls, often because of uncertainty by nurses about the use of CPR. This could be improved with clearer guidelines in hospitals about the value of CPR in selected patients. [ABSTRACT FROM PUBLISHER]

Morphological, taxonomic, and field observations on the ecology of the monotypic narrowly endemic genus Geocarponin southeastern Arkansas are presented, and the presence of anthocyanin pigments is demonstrated in plants of Geocarpon minimum, providing further support for its placement in the Caryophyllaceae rather than in the Aizoaceae to which it was originally assigned.

Mediastinal lymphadenopathy is commonly detected on CT. It is a non-specific finding, but because of its significance in the treatment in lung carcinoma it is important to know with which other disease states it is associated. We present a series of 42 patients in whom CT of the chest was used to confirm a clinical diagnosis of bronchiectasis. The size, number and distribution of mediastinal lymph nodes is documented. Lymph nodes were visible in 81% of patients. Nodes larger than 10 mm, the recognised maximum size for normal nodes in the U. K., were detected in 29%. In the absence of other recognised causes of lymphadenopathy in these patients, these findings confirm “reactive” mediastinal lymph node enlargement in bronchiectasis.