Relationship between intracellular proton buffering capacity and intracellular pH

Relationship between intracellular proton buffering capacity and intracellular pH. In a recent publication the widely held view that the intracellular proton buffering power [defined as the amount of acid or base that has to be added to the cytosol to change the intracellular pH (pHi) by one pH unit] increases as the intracellular pH decreases, has been challenged, with the opposite relationship being proposed. In that publication, buffering was defined not in terms of pH change, but in terms of the change in proton concentration. The reason for this re-definition was the fear that the conventional analysis, using as it does a logarithmic function (pHi), could bias the outcome in favor of an increasing buffering power with decreasing pHi. The new system uses a “buffering co-efficient,” defined as the number of protons necessary to be added to the cytosol to change the intracellular proton concentration by 1 mM. We report the use of both of these methods to analyze the relationship of pHi and buffering power, using human peripheral leucocytes loaded with the pH-sensitive fluorophore BCECF examined over a very wide range of pHi values (pHi 6.0 to 7.5). The most common method for pHi perturbation for the measurement of buffering is used, the rapid diffusion of ammonia across the cell membrane. In this study, analysis for both a bicarbonate-containing “open” system and for a Hepes-buffered “closed” system was performed. Unlike the previous publication, the intracellular and extracellular conditions were such that the change in pHi induced by the extracellular addition of an ammonia-containing compound (NH4Cl) was the same (0.15 to 0.25 pH unit) across the pHi range of 6.0 to 7.5. The pHrbuffering relationship varied depending on the analysis used, but taking into account the known properties of Na+/H+ exchange and the desirability of defence of the cell against intracellular acidosis, the traditional relationship seems conceptually to be the more satisfactory

SWAS and Arecibo observations of H2O and OH in a diffuse cloud along the line-of-sight to W51

Observations of W51 with the Submillimeter Wave Astronomy Satellite (SWAS) have yielded the first detection of water vapor in a diffuse molecular cloud. The water vapor lies in a foreground cloud that gives rise to an absorption feature at an LSR velocity of 6 km/s. The inferred H2O column density is 2.5E+13 cm-2. Observations with the Arecibo radio telescope of hydroxyl molecules at ten positions in W51 imply an OH column density of 8E+13 cm-2 in the same diffuse cloud. The observed H2O/OH ratio of ~ 0.3 is significantly larger than an upper limit derived previously from ultraviolet observations of the similar diffuse molecular cloud lying in front of HD 154368. The observed variation in H2O/OH likely points to the presence in one or both of these clouds of a warm (T > 400) gas component in which neutral-neutral reactions are important sources of OH and/or H2O.Comment: 15 pages (AASTeX) including 4 (eps) figures. To appear in the Astrophysical Journa

Herschel Search for O_2 toward the Orion Bar

We report the results of a search for molecular oxygen (O_2) toward the Orion Bar, a prominent photodissociation region at the southern edge of the H II region created by the luminous Trapezium stars. We observed the spectral region around the frequency of the O_2 NJ = 33-12 transition at 487 GHz and the 5_(4)-3_(4) transition at 774 GHz using the Heterodyne Instrument for the Far-Infrared on the Herschel Space Observatory. Neither line was detected, but the 3σ upper limits established here translate to a total line-of-sight O2 column density <1.5 × 10^(16) cm^(–2) for an emitting region whose temperature is between 30 K and 250 K, or <1 × 10^(16) cm^(–2) if the O_2 emitting region is primarily at a temperature of ≲100 K. Because the Orion Bar is oriented nearly edge-on relative to our line of sight, the observed column density is enhanced by a factor estimated to be between 4 and 20 relative to the face-on value. Our upper limits imply that the face-on O_2 column density is less than 4 × 10^(15) cm^(–2), a value that is below, and possibly well below, model predictions for gas with a density of 10^(4)-10^(5) cm^(–3) exposed to a far-ultraviolet flux 10^4 times the local value, conditions inferred from previous observations of the Orion Bar. The discrepancy might be resolved if (1) the adsorption energy of O atoms to ice is greater than 800 K; (2) the total face-on A V of the Bar is less than required for O_2 to reach peak abundance; (3) the O_2 emission arises within dense clumps with a small beam filling factor; or (4) the face-on depth into the Bar where O_2 reaches its peak abundance, which is density dependent, corresponds to a sky position different from that sampled by our Herschel beams

Why students engage in simulation and how it prepares them for work

In the future, learning will take the shape of a story, a play, a game; involving multiple platforms and players; driven by dialogue and augmented with technology, an interplay of immersive experiences, data, and highly social virtual worlds (Lee et al., 2021). Employers seek graduates who demonstrate attributes that organisations require to develop in the future. As students transition out of higher education, they should have the ‘abilities and capabilities to maintain employment’ (Asiri et al., 2017 p. 2). The transition out of university can be perceived as particularly stressful, with uncertainty about what is required for a successful career (Jackson and Tomlinson, 2020). This is exacerbated in the post Covid-19 environment when, even as the graduate job market has started to recover, students’ confidence about finding a job after graduation remains low (Curnock Cook, 2022). Our simulation methods are aligned to the theories that underpin these transitions, and designed to support students ‘becoming’ professionals in their field. Simulations can be designed for cognitive absorption, the psychological concept of flow and deep absorption in learning (Kukulska-Hulme et al., 2022). Premised on the innovation of best learning moments, the student tasks shared in this workshop engender deep involvement, through memorable learning activities. This reflects the ‘ways of working’ of the Learning Development (LD) community, and evidence suggests that reflective practice, Biggins, Holley, Goldsmith and Priego-Hernández Why students engage with simulation and how it prepares them for work. Journal of Learning Development in Higher Education, Special Issue 29: October 2023. Learning complex skills and scaffolding learning are the transferable aspects of these technologies (Chernikova et al., 2020). Widening participation research has provided evidence that students’ movements in and out of experiences such as care, work and studies are dynamic, non-sequential and context-dependent (Holley and Priego-Hernández, 2021). With the move to hybrid learning, students want their learning materials to be well-designed. However, 43% of students do not perceive their learning materials to be engaging/motivating (Killen and Didymus, 2022). Immersive technology and simulation may offer the solution to this disconnect, as simulations offer an immersive and embodied experience (Bayne 2004; Bayne et al., 2019). Signature pedagogies (Thomson et al., 2012) for professions can provide a means for institutions to achieve the requirements of Office for Students’ B3 (2022) which is now assessing student continuation, degree outcomes, including differential outcomes for student characteristics, and, framing this workshop, graduate employment and progression to professional jobs and postgraduate study. Learning Developers have a pivotal part to play operationalising actions that result into students’ graduate outcomes, and responding to this, our workshop invited participants to experience three types of simulation: a) a business game; b) a mass casualty evacuation; and c) a community project responding to a scenario

Lack of evidence does not justify neglect. how can we address unmet medical needs in calciphylaxis

Calcific uraemic arteriolopathy (CUA), or calciphylaxis, is a rare disease predominantly occurring in comorbidity with dialysis. Due to the very low frequency of CUA, prospective studies on its management are lacking and even anecdotal reports on treatment remain scarce. Therefore, calciphylaxis is still a challenging disease with dismal prognosis urgently requiring adequate strategies for diagnosis and treatment.In an attempt to fill some of the current gaps in evidence on various, highly debated and controversial aspects of dialysis-associated calciphylaxis, 13 international experts joined the 1st Consensus Conference on CUA, held in Leuven, Belgium on 21 September 2015. The conference was supported by the European Calciphylaxis Network (EuCalNet), which is a task force of the ERA-EDTA scientific working group on Chronic Kidney Disease-Mineral and Bone Disorders (CKD-MBD). After an intense discussion, a 9-point Likert scale questionnaire regarding 20 items on calciphylaxis was anonymously answered by each participant. These 20 items addressed unsolved issues in terms of diagnosis and management of calciphylaxis. On the one hand, the analysis of the expert opinions identified areas of general consensus, which might be a valuable aid for physicians treating such a disease with less experience in the field. On the other hand, some topics such as the pertinence of skin biopsy and administration of certain treatments revealed divergent opinions. The aim of the present summary report is to provide some guidance for clinicians who face patients with calciphylaxis in the current setting of absence of evidence-based medicin

Fitbit®: An accurate and reliable device for wireless physical activity tracking

Although physicians recognize the importance of physical activity in the prevention and maintenance of chronic diseases, few incorporate physical activity counseling into routine clinic visits. One major barrier has been the paucity of means to objectively assess patient's long-term physical activity patterns. We investigated if the Fitbit®, one of the most common wireless physical activity trackers in the consumer market, met reasonable validity and reliability standards such that they could be used by primary care physicians to monitor their patient's physical activity objectively between clinic visits. Keywords: Physical activity; Validation; Activity monitoring; Accelerometer; Walking; Fitbi

Submillimeter Wave Astronomy Satellite mapping observations of water vapor around Sagittarius B2

Observations of the 1(10)-1(01) 556.936 GHz transition of ortho-water with the Submillimeter Wave Astronomy Satellite (SWAS) have revealed the presence of widespread emission and absorption by water vapor around the strong submillimeter continuum source Sagittarius B2. An incompletely-sampled spectral line map of a region of size 26 x 19 arcmin around Sgr B2 reveals three noteworthy features. First, absorption by foreground water vapor is detectable at local standard-of-rest (LSR) velocities in the range -100 to 0 km/s at almost every observed position. Second, spatially-extended emission by water is detectable at LSR velocities in the range 80 to 120 km/s at almost every observed position. This emission is attributable to the 180-pc molecular ring identified from previous observations of CO. The typical peak antenna temperature of 0.075 K for this component implies a typical water abundance of 1.2E-6 to 8E-6 relative to H2. Third, strong absorption by water is observed within 5 arcmin of Sgr B2 at LSR velocities in the range 60 to 82 km/s. An analysis of this absorption yields a H2O abundance ~ 2E-7 to 4E-7 relative to H2 if the absorbing water vapor is located within the core of Sgr B2 itself; or, alternatively, a water column density ~ 2.5E+16 to 4E+16 per cm2 if the water absorption originates in the warm, foreground layer of gas proposed previously as the origin of ammonia absorption observed toward Sgr B2.Comment: 29 pages (AASTeX), including 9 postscript figures, to appear in the Astrophysical Journa

Using HSV-Thymidine Kinase for Safety in an Allogeneic Salivary Graft Cell Line

Extreme salivary hypofunction is a result of tissue damage caused by irradiation therapy for cancer in the head and neck region. Unfortunately, there is no currently satisfactory treatment for this condition that affects up to 40,000 people in the United States every year. As a novel approach to managing this problem, we are attempting to develop an orally implantable, fluid-secreting device (an artificial salivary gland). We are using the well-studied HSG salivary cell line as a potential allogeneic graft cell for this device. One drawback of using a cell line is the potential for malignant transformation. If such an untoward response occurred, the device could be removed. However, in the event that any HSG cells escaped, we wished to provide additional patient protection. Accordingly, we have engineered HSG cells with a hybrid adeno-retroviral vector, AdLTR.CMV-tk, to express the herpes simplex virus thymidine kinase (HSV-tk) suicide gene as a novel safety factor. Cells were grown on plastic plates or on poly-L-lactic acid disks and then transduced with different multiplicities of infection (MOIs) of the hybrid vector. Thereafter, various concentrations of ganciclovir (GCV) were added, and cell viability was tested. Transduced HSG cells expressed HSV-tk and were sensitive to GCV treatment. Maximal effects were seen at a MOI of 10 with 50 μM of GCV, achieving 95% cell killing on the poly-L-lactic acid substrate. These results suggest that engineering the expression of a suicide gene in an allogeneic graft cell may provide additional safety for use in an artificial salivary gland device.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63119/1/10763270152436463.pd

Distribution of Water Vapor in Molecular Clouds

We report the results of a large-area study of water vapor along the Orion Molecular Cloud ridge, the purpose of which was to determine the depth-dependent distribution of gas-phase water in dense molecular clouds. We find that the water vapor measured toward 77 spatial positions along the face-on Orion ridge, excluding positions surrounding the outflow associated with BN/KL and IRc2, display integrated intensities that correlate strongly with known cloud surface tracers such as CN, C2H, 13CO J =5-4, and HCN, and less well with the volume tracer N2H+. Moreover, at total column densities corresponding to Av < 15 mag., the ratio of H2O to C18O integrated intensities shows a clear rise approaching the cloud surface. We show that this behavior cannot be accounted for by either optical depth or excitation effects, but suggests that gas-phase water abundances fall at large Av. These results are important as they affect measures of the true water-vapor abundance in molecular clouds by highlighting the limitations of comparing measured water vapor column densities with such traditional cloud tracers as 13CO or C18O. These results also support cloud models that incorporate freeze-out of molecules as a critical component in determining the depth-dependent abundance of water vapor