Turning the tide of parachute science

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Spectral characteristics of airway opening and chest wall tidal flows in spontaneously breathing preterm infants.

We compared the harmonic content of tidal flows measured simultaneously at the mouth and chest wall in spontaneously breathing very low birth weight infants (n = 16, 1,114 +/- 230 g, gestation age: 28 +/- 2 wk). Airway opening flows were measured via face mask-pneumotachograph (P-tach), whereas chest wall flows were derived from respiratory inductance plethysmography (RIP) excursions. Next, for each, we computed two spectral shape indexes: 1) harmonic distortion (k(d); k(d,P-tach) and k(d,RIP), respectively) defines the extent to which flows deviated from a single sine wave, and 2) the exponent of the power law (s; s(P-tach) and s(RIP), respectively), describing the spectral energy vs. frequency. P-tach and RIP flow spectra exhibited similar power law functional forms consistently in all infants. Also, mouth [s(P-tach) = 3.73 +/- 0.23% (95% confidence interval), k(d,P-tach) = 38.8 +/- 4.6%] and chest wall (s(RIP) = 3.51 +/- 0.30%, k(d,RIP) = 42.8 +/- 4.8%) indexes were similar and highly correlated (s(RIP) = 1.17 x s(P-tach) + 0.85; r(2) = 0.81; k(d,RIP) = 0.90 x k(d,P-tach) + 8.0; r(2) = 0.76). The corresponding time to peak tidal expiratory flow-to-expiratory time ratio (0.62 +/- 0.08) was higher than reported in older infants. The obtained s and k(d) values are similar to those reported in older and/or larger chronic lung disease infants, yet appreciably lower than for 1-mo-old healthy infants of closer age and/or size; this indicated increased complexity of tidal flows in very low birth weight babies. Importantly, we found equivalent flow spectral data from mouth and chest wall tidal flows. The latter are desirable because they avoid face mask artificial effects, including leaks around it, they do not interfere with ventilatory support delivery, and they may facilitate longer measurements that are useful in control of breathing assessment.     

Scribed transparency microplates mounted on a modified standard microplate

The immense cost effectiveness of using transparencies as analyte handling implements in microplate instrumentation offers the possibility of application even in resource-limited laboratories. In this work, a standard microplate was adapted to serve as the permanent base for disposable scribed transparencies. The approach is shown to ameliorate evaporation, which can affect assay accuracy when analytes need to be incubated for some time. It also offers assurance against fluorescence measurement errors due to the cross-talk of samples from adjacent wells.     

Irreversible thermodynamic model equations of the transport across a horizontally mounted membrane

The Kedem-Katchalsky-Zelman model equations for transmembrane transport in multicomponent, non-ionic and heterogeneous solutions have been modified. The validity of this model for binary and ternary solutions was verified, using a cell with a horizontally mounted membrane. In the cell, volume and solute fluxes were measured as a function of gravitational configuration. In the experimental set-up, water was placed on one side of the membrane. The opposite side of the membrane was exposed to aqueous solutions of densities greater than that of water, aqueous ethanol (less dense than water) or glucose/ethanol/water solutions. The experimental results presented herein illustrate pseudo-phase transitions which occur from a non-convectional to convectional state or in the reverse direction.     

Corals fail to recover at a Caribbean marine reserve despite ten years of reserve designation

The ability of reserves to replenish fish stocks is relatively well documented, but the evidence of their ability to induce positive effects on benthic communities remains inconclusive. Here, we test whether 10 years of reserve designation have translated into positive effects on coral communities in Glover’s Reef, Belize. Surveys of 87 patch reefs inside and outside the reserve revealed no clear indication of reserve implementation benefitting coral cover, coral colony size, or abundance of juvenile corals. Furthermore, massive broadcasting coral species exhibited greater losses over time than their smaller-sized counterparts across all sites, suggesting that local management actions have not alleviated the regional trend of high mortality for these species. We detected no difference in herbivorous fish abundances or macroalgal cover between reserve and fished sites, providing a potential explanation for the lack of cascading positive effects on the coral community. We conclude that patterns of regional coral decline are evident at Glover’s Reef, including a shift in dominance from broadcasting species to brooding species and declines in mean colony size. Our findings suggest that regional stressors are overwhelming local management efforts and that additional strategies are required to improve local coral condition.     

Exuberant accessory mitral valve tissue with possible true parachute mitral valve: a case report

ABSTRACT: INTRODUCTION: A parachute mitral valve is defined as a unifocal attachment of mitral valve chordae tendineae independent of the number of papillary muscles. Data from the literature suggests that the valve can be distinguished on the basis of morphological features as either a parachute-like asymmetrical mitral valve or a true parachute mitral valve. A parachute-like asymmetrical mitral valve has two papillary muscles; one is elongated and located higher in the left ventricle. A true parachute mitral valve has a single papillary muscle that receives all chordae, as was present in our patient. Patients with parachute mitral valves during childhood have multilevel left-side heart obstructions, with poor outcomes without operative treatment. The finding of a parachute mitral valve in an adult patient is extremely rare, especially as an isolated lesion. In adults, the unifocal attachment of the chordae results in a slightly restricted valve opening and, more frequently, valvular regurgitation. CASE PRESENTATION: A 40-year-old Caucasian female patient was admitted to a primary care physician due to her recent symptoms of heart palpitation and chest discomfort on effort. Transthoracic echocardiography showed chordae tendineae which were elongated and formed an unusual net shape penetrating into left ventricle cavity. The parasternal short axis view of her left ventricle showed a single papillary muscle positioned on one side in the posteromedial commissure receiving all chordae. Her mitral valve orifice was slightly eccentric and the chordae were converting into a single papillary muscle. Mitral regurgitation was present and it was graded as moderate to severe. Her left atrium was enlarged. There were no signs of mitral stenosis or a subvalvular ring. She did not have a bicuspid aortic valve or coarctation of the ascending aorta. The dimensions and systolic function of her left ventricle were normal. Our patient had a normal body habitus, without signs of heart failure. Her functional status was graded as class I according to the New York Heart Association grading. CONCLUSIONS: A recently published review found that, in the last several decades, there have been only nine adult patients with parachute mitral valve disease reported, of which five had the same morphological characteristics as our patient. This case presentation should encourage doctors, especially those involved in echocardiography, to contribute their own experience, knowledge and research in parachute mitral valve disease to enrich statistical and epidemiologic databases and aid clinicians in getting acquainted with this rare disease.     

Low genetic diversity in a marine nature reserve: re-evaluating diversity criteria in reserve design

Little consideration has been given to the genetic composition of populations associated with marine reserves, as reserve designation is generally to protect specific species, communities or habitats. Nevertheless, it is important to conserve genetic diversity since it provides the raw material for the maintenance of species diversity over longer, evolutionary time-scales and may also confer the basis for adaptation to environmental change. Many current marine reserves are small in size and isolated to some degree (e.g. sea loughs and offshore islands). While such features enable easier management, they may have important implications for the genetic structure of protected populations, the ability of populations to recover from local catastrophes and the potential for marine reserves to act as sources of propagules for surrounding areas. Here, we present a case study demonstrating genetic differentiation, isolation, inbreeding and reduced genetic diversity in populations of the dogwhelk Nucella lapillus in Lough Hyne Marine Nature Reserve (an isolated sea lough in southern Ireland), compared with populations on the local adjacent open coast and populations in England, Wales and France. Our study demonstrates that this sea lough is isolated from open coast populations, and highlights that there may be long-term genetic consequences of selecting reserves on the basis of isolation and ease of protection.     

Development and validation of a finite element model to simulate the opening of a medial opening wedge high tibial osteotomy

Medial opening wedge high tibial osteotomy (MOWHTO) is a surgical procedure intended to alter the coronal and sagittal plane alignment of the lower limb to primarily relieve the symptoms of osteoarthritis in the medial compartment of the knee. The purpose of this work was to develop and validate a finite element model to simulate the opening of a high tibial osteotomy and determine whether a pilot hole at the cortical hinge reduces the risk of lateral cortical fracture. Fifteen models were reconstructed from CT images of eight cadaveric specimens. The validated models indicated that the addition of the pilot hole increased the stresses and likelihood of a type-I and type-II fractures during the opening of a medial open wedge high tibial osteotomy compared to the no-hole condition.     

Flower opening and closure: a review

Flower opening and closure are traits of a reproductive syndrome, as it allows pollen removal and/or pollination. Various types of opening can be distinguished such as nocturnal and diurnal and single or repetitive. Opening is generally due to cell expansion. Osmotic solute levels increase by the conversion of polysaccharides (starch or fructan) to monosaccharides, and/or the uptake of sugars from the apoplast. Repeated opening and closure movements are often brought about by differential elongation. In tulip petals, for example, the upper and lower sides of the mesophyll exhibit a 10 degrees C difference in optimum temperature for elongation growth, resulting in opening in the morning and closure in the evening. Opening and closure in several other species is regulated by changes in light intensity and, in some species with nocturnal opening, by an increase in relative humidity. A minimum duration of darkness and light are usually required for opening and closure, respectively, in flowers that open during the day. Both phytochrome and a blue light receptor seem involved in light perception. In some species, opening and closure are regulated by an endogenous rhythm, which, in all cases investigated, can be reset by changes from dark to light and/or light to dark. So far, Arabidopsis mutants have not been used to investigate the timing of flower opening and closure. As its flowers open and close in a circadian fashion, several mutants that are involved in the circadian clock and its light input may help to provide an insight into this type of flower opening. The co-ordination of processes culminating in synchronized flower opening is, in many species, highly intricate. The complex control by endogenous and exogenous factors sets flower opening and closure apart from most other growth processes.     

Analysis of conserved domains identifies a unique structural feature of a chloroplast heat shock protein

Summary A low molecular weight heat shock protein which localizes to chloroplasts has been identified in several plant species. This protein belongs to a eukaryotic superfamily of small HSPs, all of which contain a conserved carboxyl-terminal domain. To investigate further the structure of this HSP, we isolated and sequenced cDNA clones for the chloroplast LMW HSPs from Petunia hybrida and Arabidopsis thaliana. The cloning of chloroplast HSPs from these two species enabled us to compare the amino acid sequences of this protein from plant species (petunia, Arabidopsis, pea, soybean and maize) that represent evolutionarily divergent taxonomic subclasses. Three conserved regions were identified, which are designated as regions I, II and III. Regions I and II are also shared by cytoplasmic LMW HSPs and therefore are likely to have functional roles common to all eukaryotic LMW HSPs. In contrast, consensus region III is not found in other LMW HSPs. Secondary structure analysis predicts that this region forms an amphipathic -helix with high conservation of methionine residues on the hydrophobic face and 100% conservation of residues on the hydrophilic face. This structure is similar to three helices, termed methionine bristles, which are found in a methionine-rich domain of a 54 kDa protein component of signal recognition particle (SRP54). The conservation of regions I and II among LMW cytoplasmic and chloroplast HSPs suggests that these HSPs perform related functions in different cellular compartments. However, identification of the methionine bristle domain suggests that chloroplast HSPs also have unique functions or substrates within the special environment of the chloroplast or other plastids.Abbreviations HS heat shock - HSP heat shock protein - LMW low molecular weight     

Membrane capacitance in frog cut twitch fibers mounted in a double vaseline-gap chamber

In experiments on cut muscle fibers mounted in a double Vaseline-gap chamber, electrical measurements are usually made by measuring the voltage V1(t) in one end pool and by passing current I2(t) from the other end pool to the central pool, which is usually clamped to earth potential. The voltage in the current-passing end pool is denoted by V2(t). This article describes how the value of the holding current, Ih, and the values of delta V2(infinity)/delta V1(infinity) and delta I2(infinity)/delta V1(infinity) that are associated with a small change in V1(t) can be used to estimate the linear cable parameters rm, ri, and re in a cut fiber that has been equilibrated with a Cs-containing internal solution. rm, ri, and re represent, respectively, the resistance of the plasma membranes, the internal longitudinal resistance, and the external longitudinal resistance under the Vaseline seals, all for a unit length of fiber. The apparent capacitance, Capp, of the preparation is defined to equal integral of infinity 0 delta I2,tr(t) dt/delta V1(infinity), in which delta I2,tr(t) represents the transient component of current that is associated with a change in V1(t) of amplitude delta V1(infinity). A method is described to estimate cm, the capacitance of the plasma membranes per unit length of fiber, from Capp and the values of rm, ri, and re. In experiments carried out with a tetraethylammonium chloride (TEA.Cl) solution at 13-14 degrees C in the central pool, cm remained stable for as long as 3-4 h. The values of cm, 0.19 microF/cm on average, and their variation with fiber diameter are similar to published results from intact fibers. This article also describes the different pathways that are taken by the current that flows from the current-passing end pool to the central pool. Approximately two-thirds of delta I2,tr(t) flows across the capacitance of the plasma membranes in the central-pool region. The rest flows either across plasma membranes that are under the two Vaseline seals or directly from the current-passing end pool to the central pool, across the external longitudinal resistance under the Vaseline seal. [There is also a current that flows directly from the voltage-measuring end pool to the central pool but this does not contribute to delta I2,tr(t).]