Bronchiolitis obliterans in a patient previously working as a printer in a textile factory

We report the case of a 24-year-old man with a diagnosis of bronchiolitis obliterans, a rare clinical condition; the similarity to Ardystil syndrome was striking. Relevant occupational history included work in a textile air-brushing factory. Also noteworthy were lesions observed by CT scan in the form of cystic formations measuring less than 1 cm, a finding not previously described in the context of bronchiolitis obliterans. The patient improved immediately after starting corticoid treatment although scans failed to improve over several months of follow-up.     

Charge of a quasiparticle in a superconductor

Nonlinear charge transport in superconductor–insulator–superconductor (SIS) Josephson junctions has a unique signature in the shuttled charge quantum between the two superconductors. In the zero-bias limit Cooper pairs, each with twice the electron charge, carry the Josephson current. An applied bias V_SD leads to multiple Andreev reflections (MAR), which in the limit of weak tunneling probability should lead to integer multiples of the electron charge ne traversing the junction, with n integer larger than 2Δ/eV_SD and Δ the superconducting order parameter. Exceptionally, just above the gap eV_SD ≥ 2Δ, with Andreev reflections suppressed, one would expect the current to be carried by partitioned quasiparticles, each with energy-dependent charge, being a superposition of an electron and a hole. Using shot-noise measurements in an SIS junction induced in an InAs nanowire (with noise proportional to the partitioned charge), we first observed quantization of the partitioned charge q = e*/e = n, with n = 1–4, thus reaffirming the validity of our charge interpretation. Concentrating next on the bias region eV_SD ～ 2Δ, we found a reproducible and clear dip in the extracted charge to q? ～ 0.6, which, after excluding other possibilities, we attribute to the partitioned quasiparticle charge. Such dip is supported by numerical simulations of our SIS structure.Excitations in superconductors (Bogoliubov quasiparticles) can be described according to the Bardeen–Cooper–Schrieffer (BCS) theory (1) as an energy-dependent superposition of an electron with amplitude u(ε), and a hole with amplitude v(ε), where the energy ε is measured relative to the Fermi energy (2). Evidently, the expectation value of the charge operator (applied to the quasiparticle wave function), which we address as the quasiparticle charge e* = q(ε)e, is smaller than the charge of an electron, q(ε) = |u(ε)|² ? |ν(ε)|² (3). Solving the Bogoliubov–de Gennes equations, one finds that |u(ε)|2=1/2[1+(ε2−Δ2/ε)] and |v(ε)|2=1/2[1−(ε2−Δ2/ε)], with the expected charge evolving with energy according to q(ε)=ε2−Δ2/ε––vanishing altogether at the superconductor gap edges (3). Note, however, that the quasiparticle wave function is not an eigenfunction of the charge operator (3, 4). Properties of quasiparticles, such as the excitation spectra (5), lifetime (6–10), trapping (11), and capturing by Andreev bound states (12, 13), had already been studied extensively; however, studies of their charge are lagging. In the following we present sensitive shot-noise measurements in a Josephson junction, resulting in a clear observation of the quasiparticle charge being smaller than e, q(eV_SD∼2Δ) < 1, and evolving with energy, as expected from the BCS theory.To observe the BCS quasiparticles in transport we study a superconductor–insulator–superconductor (SIS) Josephson junction in the nonlinear regime. The overlap between the wave functions of the quasiparticles in the source and in the drain is expected to result in a tunneling current of their effective charge. This is in contrast with systems which are incoherent (14, 15) or with an isolated superconducting island, where charge conservation leads to traversal of multiples of e – Coulomb charge (16). As current transport in the nonlinear regime results from “multiple Andreev reflections” (MAR), it is prudent to make our measurements credible by first measuring the charge in this familiar regime.In short, the MAR process, described schematically in Fig. 1, carries a signature of the shuttled charge between the two superconductors (SCs), being a consequence of n traversals through the junction (as electron-like and hole-like quasiparticles), with n an integer larger than 2Δ/eV_SD. A low transmission probability t (via tunneling through a barrier) in the bias range 2Δ/n < eV_SD < 2Δ/(n ? 1) assures dominance of the lowest order MAR process (higher orders are suppressed as tⁿ), with the charge evolving in nearly integer multiples of the electron charge. Although there is already a substantial body of theoretical (3, 17–23) and experimental (24–29) studies of the MAR process, charge determination without adjustable parameters is still missing. An important work by Cron et al. (27) indeed showed a staircase-like behavior of the charge using “metallic break junctions;” however, limited sensitivity and the presence of numerous conductance channels some of which with relatively high transmission probabilities did not allow exact charge quantization. Our shot-noise measurements, performed on a quasi-1D Josephson junction (single-mode nanowire) allowed clear observation of charge quantization without adjustable parameters. To count a few advantages: (i) the transmission of the SIS junction could be accurately controlled using a back-gate; (ii) this, along with our high sensitivity in noise measurements, enabled us to pinch the junction strongly (thus suppressing higher MAR orders); and (iii) with the Fermi level located near the 1D channel van Hove singularity, a rather monoenergetic distribution could be injected (SI Appendix, section S7).Open in a separate windowFig. 1.MAR. Illustrations of the leading processes contributing to the current as function of bias. In general, for 2Δ/(n ? 1) > eV_SD > 2Δ/n the leading charge contribution to the current is ne. An electron-like quasiparticle is denoted by a full circle, whereas a hole-like quasiparticle is denoted by an empty circle. (A) When the bias is larger than the energy gap, eV_SD > 2Δ, the leading process is a single-path tunneling of single quasiparticles from the full states (Left) to the empty states (Right). This current is proportional to the transmission coefficient t. Higher-order MAR process (dashed box), being responsible for tunneling of Cooper pairs, is suppressed as t². (B) For 2Δ > eV_SD > Δ, the main charge contributing to the current is 2e with probability t². (C) For Δ > eV_SD > 2Δ/3, the main charge contributing to the current is 3e with probability t³.     

Nasopharyngeal angiofibroma in a patient with haemophilia A: a bleeding tumour in a bleeding-prone patient

Nasopharyngeal angiofibroma is a highly vascular tumour which occurs almost exclusively in adolescent males. Although it is histologically benign, it may cause serious clinical problems because of its tendency to bleed profusely during surgery. This paper presents the first case of nasopharyngeal angiofibroma in a patient with haemophilia A, another well-known disease of bleeding tendency. In this case the tumoural mass was surgically removed with effective factor VIII replacement without any bleeding complication.     

Managing a traumatic wound in a geriatric patient

Clinical management of a wound in a geriatric patient requires an understanding of age-related changes in the skin and the knowledge to make appropriate treatment choices. This case study describes clinical assessment and management of a traumatic hip wound in a 75-year-old patient. In addition to addressing his nutritional status by providing supplements, topical wound care preparations, including papain-urea and castor oil/balsam of Peru/trypsin, were used as a conservative approach to address debridement and periwound skin concerns. Extra vigilance is required to assess wounds in geriatric patients to determine proper wound treatment and achieve optimum results. Additional studies to evaluate optimal treatment strategies in the clinical management of traumatic wounds in the geriatric population are needed.     

Fate of a mutation in a fluctuating environment

Natural environments are never truly constant, but the evolutionary implications of temporally varying selection pressures remain poorly understood. Here we investigate how the fate of a new mutation in a fluctuating environment depends on the dynamics of environmental variation and on the selective pressures in each condition. We find that even when a mutation experiences many environmental epochs before fixing or going extinct, its fate is not necessarily determined by its time-averaged selective effect. Instead, environmental variability reduces the efficiency of selection across a broad parameter regime, rendering selection unable to distinguish between mutations that are substantially beneficial and substantially deleterious on average. Temporal fluctuations can also dramatically increase fixation probabilities, often making the details of these fluctuations more important than the average selection pressures acting on each new mutation. For example, mutations that result in a trade-off between conditions but are strongly deleterious on average can nevertheless be more likely to fix than mutations that are always neutral or beneficial. These effects can have important implications for patterns of molecular evolution in variable environments, and they suggest that it may often be difficult for populations to maintain specialist traits, even when their loss leads to a decline in time-averaged fitness.Evolutionary trade-offs are widespread: Adaptation to one environment often leads to costs in other conditions. For example, drug resistance mutations often carry a cost when the dosage of the drug decays (1), and seasonal variations in climate can differentially select for certain alleles in the summer or winter (2). Similarly, laboratory adaptation to specific temperatures (3, 4) or particular nutrient sources (5, 6) often leads to declines in fitness in other conditions. Related trade-offs apply to any specialist phenotype or regulatory system that incurs a general cost to confer benefits in specific environmental conditions (7). Despite the ubiquity of these trade-offs, it is not always easy to predict when a specialist phenotype can evolve and persist. How useful must a trait be on average to be maintained? How regularly does it need to be useful? How much easier is it to maintain in a larger population compared with a smaller one?The answers to these questions depend on two major factors. First, how often do new mutations create or destroy a specialist phenotype, and what are their typical costs and benefits across environmental conditions? This is fundamentally an empirical question, which depends on the costs and benefits of the trait in question, as well as its genetic architecture (e.g., the target size for loss-of-function mutations that disable a regulatory system). In this paper, we focus instead on the second major factor: given that a particular mutation occurs, how does its long-term fate depend on its fitness in each condition and on the details of the environmental fluctuations?To address this question, we must analyze the fixation probability of a new mutation that experiences a time-varying selection pressure. This is a classic problem in population genetics, and has been studied by a number of previous authors. The effects of temporal fluctuations are simplest to understand when the timescales of environmental and evolutionary change are very different. For example, when the environment changes more slowly than the fixation time of a typical mutation, its fate will be entirely determined by the environment in which it arose (8). On the other hand, if environmental changes are sufficiently rapid, then the fixation probability of a mutation will be determined by its time-averaged fitness effect (9, 10). In these extreme limits, the environment can have a profound impact on the fixation probability of a new mutation, but the fluctuations themselves play a relatively minor role. In both cases, the effects of temporal variation can be captured by defining a constant effective selection pressure, which averages over the environmental conditions that the mutation experiences during its lifetime. This result is the major reason why temporally varying selection pressures are neglected throughout much of population genetics, despite the fact that truly constant environments are rare.However, this simple result is crucially dependent on the assumption that environmental changes are much slower or much faster than all evolutionary processes. When these timescales start to overlap, environmental fluctuations can have important qualitative implications that cannot be summarized by any effective selection pressure, even when a mutation experiences many environmental epochs over its lifetime. As we will show below, this situation is not an unusual special case, but a broad regime that becomes increasingly relevant in large populations. In this regime, the fate of each mutation depends critically on its fitness in each environment, the dynamics of environmental changes, and the population size.Certain aspects of this process have been analyzed in earlier studies. Much of this earlier work focuses on the dynamics of a mutation in an infinite population (11–24). However, these infinite-population approaches are fundamentally unsuitable for analyzing the fixation probabilities of mutations that are neutral or deleterious on average (and even for mutations that are beneficial on average, population sizes must often be unrealistically large for this infinite population size approximation to hold). Another class of work has focused explicitly on finite populations, but only in the case where the environment varies stochastically from one generation to the next (25–31). Later work has extended this analysis to fluctuations on somewhat longer timescales, but this work is still restricted to the special case where selection cannot change allele frequencies significantly during an individual environmental epoch (9, 32, 33).These studies have provided important qualitative insights into various aspects of environmental fluctuations. However, we still lack both a quantitative and conceptual understanding of more significant fluctuations, where selection in each environment can lead to measurable changes in allele frequency. This gap is particularly relevant because significant changes in allele frequency are the most clearly observable signal of variable selection in natural populations.In this work, we analyze the fate of a new mutation that arises in an environment that fluctuates between two conditions either deterministically or stochastically on any timescale. We provide a full analysis of the fixation probability of a mutation when evolutionary and environmental timescales are comparable and allele frequencies can change significantly in each epoch. We find that even in enormous populations, natural selection is often very inefficient at distinguishing between mutations that are beneficial and deleterious on average. In addition, substitution rates of all mutations are dramatically increased by variable selection pressures. This can lead to counterintuitive results. For instance, mutations that result in a trade-off but are predominantly deleterious during their lifetime can be much more likely to fix than mutations that are always neutral or even beneficial. Thus, it may often be difficult for populations to maintain specialist traits, even when loss-of-function mutations are selected against on average. This can lead to important signatures on the genetic level, e.g., in elevated rates of nonsynonymous to synonymous substitutions (dN/dS) (34).     

Manifestation of malakoplakia in a urethral diverticulum in a female patient

We report about a rare case of malakoplakia in a female urethral diverticulum. A 25-year-old patient with a long history of recurrent urinary tract infections and a plum-sized, painful swelling on the vaginal roof presented for operative treatment. In the anamnesis the patient reported about two spontaneous perforations, emptying several millilitres of pus each time. After total operative excision using a vaginal approach the histology showed malakoplakia in a urethral diverticulum. We found the typical intracytoplasmatic "Michaelis-Gutmann bodies" as well as "von Hansemann cells". Postoperatively we excluded an underlying tumour disease or a chronic infection. The further urological diagnostics (cystoscopy and MRI) were without any pathological findings. In patients with atypical cystic tumours of the urogenital tract, especially with an immune deficiency, malakoplakia should be taken in consideration. The preferred therapy is surgical management followed by long-term antibiosis as well as a close follow-up as recurrences are frequent.     

Spontaneous retroperitoneal hemorrhage in a mediastinal tumor in a patient with polymyositis: a case report

Spontaneous retroperitoneal hemorrhage is a lethal cause of acute abdomen that is most frequently related to drugs, coagulopathy and intra-abdominal tumors. In patients with polymyositis and dermatomyositis, acute abdomen is attributed to intestinal vasculitis causing ischemia, ulceration or perforation. Spontaneous retroperitoneal hemorrhage, however, has rarely been reported in patients with polymyositis. We report the case of a 65-year-old woman with newly diagnosed polymyositis and suspected thymoma who suffered from spontaneous retroperitoneal hemorrhage. She experienced two massive retroperitoneal hemorrhage episodes within 24 hours, which resulted in shock and required emergent angiographic embolization. There was no evidence of tumor, vasculitis or aneurysm from abdominal angiography and computed tomography.     

Cryptogenic stroke in a patient with a PFO: a decision analysis

BACKGROUND: Octogenarian Israeli prime-minister Ariel Sharon recently sustained a mild, reversible stroke. A patent foramen ovale (PFO) was detected and anticoagulants were given pending PFO closure. A few days later, he sustained major intracerebral hemorrhage and has since remained in vegetative state. The events triggered serious criticism in the mass media, experts promoting one management option over others. Because knowledge of outcome and hindsight bias evaluation of appropriateness of care, we sought to systematically review the clinical case. METHODS: We performed a formal decision analysis to identify the preferred management between anticoagulation, antiplatelets, PFO closure, or no treatment. Using the best evidence available, we built a decision tree. Main outcomes: recurrent stroke and treatment complications within 1 year. RESULTS: Optimal decision was found to be critically sensitive to assumptions about etiology, efficacy and safety of treatments, recurrence risk, and to small changes in utilities. In multiway sensitivity analysis, when the risk of recurrent stroke was <0.12 per year, no treatment was the best management. PFO closure is dominant only when the risk of recurrent stroke is >0.12 per year closure effectiveness is assumed to be <0.28. When closure effectiveness is >0.6, it is inferior to anticoagulation and antiplatelet management. CONCLUSIONS: Uncertainties precluded a clear-cut answer and choice was found to be a "toss-up," often associated with much controversy. Use of novel therapies, such as PFO closure, outside clinical trials will not reduce uncertainty about efficacy.