Transmission of photo-catalytic function in a self-replicating chemical system: in situ amphiphile production over two protocell generations.

Glass microsphere supported protocells were built to investigate the transmission of catalytic function during replication. The chemical system's replication was driven through in situ amphiphile production that resulted in the formation of free bilayers, the system's second "generation". It was demonstrated that both generations, once separated, still exhibited the ability to convert amphiphile precursors. This result shows that transmission of function in chemical systems is possible during self-replication.

Self-assembly of phosphate amphiphiles in mixtures of prebiotically plausible surfactants.

The spontaneous formation of closed bilayer structures from prebiotically plausible amphiphiles is an essential requirement for the emergence of early cells on prebiotic Earth. The sources of amphiphiles could have been both endo- and exogenous (accretion of meteorite carbonaceous material or interstellar dust particles). Among all prebiotic possible amphiphile candidates, those containing phosphate are the least investigated species because their self-assembly occurs in a seemingly too narrow range of conditions. The self-assembly of simple phosphate amphiphiles should, however, be of great interest, as contemporary membranes predominantly contain phospholipids. In contrast to common expectations, we show that these amphiphiles can be easily synthesized under prebiotically plausible environmental conditions and can efficiently form bilayer structures in the presence of various co-surfactants across a large range of pH values. Vesiculation was even observed in crude reaction mixtures that contained 1-decanol as the amphiphile precursor. The two best co-surfactants promoted vesicle formation over the entire pH range in aqueous solutions. Expanding the pH range where bilayer membranes self-assemble and remain intact is a prerequisite for the emergence of early cell-like compartments and their preservation under fluctuating environmental conditions. These mixed bilayers also retained small charged solutes, such as dyes. These results demonstrate that alkyl phosphate amphiphiles might have played a significant role as early compartment building blocks.

Selecting the appropriate pacing mode for patients with sick sinus syndrome: evidence from randomized clinical trials.

Several observational studies have indicated that selection of pacing mode may be important for the clinical outcome in patients with symptomatic bradycardia, affecting the development of atrial fibrillation (AF), thromboembolism, congestive heart failure, mortality and quality of life. In this paper we present and discuss the most recent data from six randomized trials on mode selection in patients with sick sinus syndrome (SSS). In pacing mode selection, VVI(R) pacing is the least attractive solution, increasing the incidence of AF and-as compared with AAI(R) pacing, also the incidence of heart failure, thromboembolism and death. VVI(R) pacing should not be used as the primary pacing mode in patients with SSS, who haven't chronic AF. AAIR pacing is superior to DDDR pacing, reducing AF and preserving left ventricular function. Single site right ventricular pacing-VVI(R) or DDD(R) mode-causes an abnormal ventricular activation and contraction (called ventricular desynchronization), which results in a reduced left ventricular function. Despite the risk of AV block, we consider AAIR pacing to be the optimal pacing mode for isolated SSS today and an algorithm to select patients for AAIR pacing is suggested. Trials on new pacemaker algorithms minimizing right ventricular pacing as well as trials testing alternative pacing sites and multisite pacing to reduce ventricular desynchronization can be expected within the next years.

Posttraumatic spinal osteolysis in ankylosing spondylitis as part of pseudoarthrosis. A case report.

A case of ankylosing spondylitis with pronounced osteolysis of the 12th thoracic vertebral body as part of posttraumatic pseudoarthrosis is described. The appearance of posttraumatic osteolysis simulates a malignant lesion, and it is important to consider the diagnosis in cases of osteolytic lesions of unknown origin.

Fatigue fracture of the sacral bone associated with septic arthritis of the symphysis pubis.

Fractures of the pubic rami are almost invariably associated with fractures of the posterior arch of the pelvic ring. Two women, aged 50 and 67 years, with septic arthritis of the symphysis pubis attended by severe low back pain, were followed with CT and MR imaging of the pelvis, as well as bond scintigraphy in one patient. In the first patient sacral fractures with severe displacement were revealed, prompting stabilizing symphysiodesis. In the second patient an undisplaced fatigue fracture was confirmed in the right half of the sacrum. In patients with pelvic laxity following arthritis of the symphysis and post-traumatic osteolysis associated with low back pain, displaced or occult fractures of the bones adjacent to the sacroiliac joints should be considered.

Estimation of kinetic rate constants from multi-channel recordings by a direct fit of the time series.

The maximum-likelihood technique for the direct estimation of rate constants from the measured patch clamp current is extended to the analysis of multi-channel recordings, including channels with subconductance levels. The algorithm utilizes a simplified approach for the calculation of the matrix exponentials of the probability matrix from the rate constants of the Markov model of the involved channel(s) by making use of the Kronecker sum and product. The extension to multi-channel analysis is tested by the application to simulated data. For these tests, three different channel models were selected: a two-state model, a three-state model with two open states of different conductance, and a three-state model with two closed states. For the simulations, time series of these models were calculated from the related first-order, finite-state, continuous-time Markov processes. Blue background noise was added, and the signals were filtered by a digital filter similar to the anti-aliasing low-pass. The tests showed that the fit algorithm revealed good estimates of the original rate constants from time series of simulated records with up to four independent and identical channels even in the case of signal-to-noise ratios being as low as 2. The number of channels in a record can be determined from the dependence of the likelihood on channel number. For large enough data sets, it takes on a maximum when the assumed channel number is equal to the "true" channel number.

Posttraumatic osteolysis of the pubic bone simulating malignancy.

Posttraumatic osteolysis (PO) of the os pubis is a diagnostic entity characterized at radiography by rapidly progressing destructive changes in fractures of the pubic body or rami. Fourteen patients with PO are here reported of whom in 8 the radiographic course of the condition was followed. They were all post-menopausal women and 7 were predisposed to osteopenia. The primary fractures were related to mild trauma in 7 patients and 7 had insufficiency fractures. Four patients had bilateral symmetrical PO. All 14 patients had concomitant insufficiency fractures of the sacrum observed at radiography, CT, scintigraphy or MR, probably due to pelvic instability caused by the PO of the os pubis. Symptoms of the sacral fractures usually dominated the clinical condition. Bony healing of the PO did not occur in any of the patients, but in all 8 patients followed radiographically, the fractures of the sacrum healed clinically and at CT. Knowledge about the condition is important to avoid unnecessary biopsy of the PO considered a metastatic lesion and/or extensive diagnostic search for a primary tumor.

[Pulmonary rheumatoid nodules. A rare disease onset in rheumatoid arthritis]. / Pulmonale reumatoide noduli. En sjoelden sygdomsdebut ved reumatoid artrit.

Rheumatoid nodules are a benign differential diagnosis to neoplasia and infection, when round lesions are accidental findings on chest X-ray. Two cases are reported of rheumatoid lung nodules as presenting features of rheumatoid arthritis. In each case, the diagnosis was verified by open biopsy.