Sigma Delta Pi Research Articles

Hematoloechus sp. attachment shifts endothelium in vivo from pro- to anti-inflammatory profile in Rana pipiens: evidence from systemic and capillary physiology.

This prospective, descriptive study focused on lung flukes (Hematoloechus sp., H) and their impact on systemic and individual capillary variables measured in pithed Rana pipiens, a long-standing model for studies of capillary physiology. Three groups were identified based on Hematoloechus attachment: no Hematoloechus (No H), Hematoloechus not attached (H Not Att), and Hematoloechus attached (H Att). Among 38 descriptive, cardiovascular, and immunological variables, 18 changed significantly with H. Symptoms of H included weight loss, elevated immune cells, heart rate variability, faster coagulation, lower hematocrit, and fluid accumulation. Important capillary function discoveries included median baselines for hydraulic conductivity (Lp) of 7.0 (No H), 12.4 (H Not Att), and 4.2 (H Att) × 10-7 cm·s-1·cmH2O-1 (P < 0.0001) plus seasonal adaptation of sigma delta pi [σ(πc-πi), P = 0.03]. Pro- and anti-inflammatory phases were revealed for Lp and plasma nitrite/nitrate concentration ([NOx]) in both H Not Att and H Att, whereas capillary wall tensile strength increased in the H Att. H attachment was advantageous for the host due to lower edema and for the parasite via a sustained food source illustrating an excellent example of natural symbiosis. However, H attachment also resulted in host weight loss: in time, a conundrum for the highly dependent parasite. The study increases overall knowledge of Rana pipiens by revealing intriguing effects of H and previously unknown, naturally occurring seasonal changes in many variables. The data improve Rana pipiens as a general scientific and capillary physiology model. Diseases of inflammation and stroke are among the clinical applications.

Sigma Delta Pi: Rediscovering a Century. 1919–2019 by Mark P. Del Mastro

Reviewed by: Sigma Delta Pi: Rediscovering a Century. 1919–2019 by Mark P. Del Mastro Mary-Anne Vetterling Del Mastro, Mark P. Sigma Delta Pi: Rediscovering a Century. 1919–2019. Juan de la Cuesta, 2020. Pp. 239. ISBN 978-1-58871-348-3. This book is a gem! Full-sized, with over 80 photos (many in color), it comes meticulously researched and is beautifully organized. Mark Del Mastro, Associate Provost and Professor of Hispanic Studies at the College of Charleston and also the Executive Director of Sigma Delta Pi, has accessed numerous documents from the Society’s files and has organized the information into a fascinating narrative that contains a vast amount of information. Not only is it a history of Sigma Delta Pi (the National Collegiate Hispanic Honor Society) but it also contains a significant amount of information about AATSP members and leaders from the past hundred years. The volume is a monument to the hard work of many who have collaborated selflessly over the years. Del Mastro’s descriptions of the various leaders of the Society are captivating in their own right and are filled with details bringing these extraordinary human beings to life. Through their accomplishments, their illnesses (including heart attacks, pancreatic cancer, premature senility, tuberculosis), he provides the reader with a sense of the hard work and persistence that have made it possible for this Society to flourish. Del Mastro includes the affiliations of each leader, following their careers from institution to institution. The first two of the 24 chapters contain a detailed description of the founding of the Society by Ruth Barnes in 1919, at the time an undergraduate at the University of California at Berkeley. Del Mastro went to great lengths to find out about Ruth, and even interviewed her granddaughter in 2018 to retrieve a fascinating but sad story about Sigma Delta Pi’s founder. The next chapter provides us with a history of the Society’s presidents. It is astounding to read how the Society grew over the years via the enormous labors and talents of its leaders. The many facets of the Society—from the organization of its local chapters, the frequent letter-writing (now emails), the task of reviving inactive chapters, the work of organizing a myriad of meetings, the managing of its finances, on through the various awards for graduates and undergraduates—can all be found in these pages and will well serve future leaders and members with the wisdom contained herein. Del Mastro’s well-informed chapter on the position of Executive Secretary-Treasurer is impressive in its listing of the many duties and responsibilities of that office. We find out about honor cords, stoles, pins, insignia, awards, official agreements with various other organizations, handbooks, upgrading to the web, creation of email distribution lists, online voting, and much more. [End Page 422] The chapter on Honorary Presidents includes biographies of a number of AATSP officers, details from the lives of several wealthy Hispanists, and brief accounts of other leaders who have enhanced Sigma Delta Pi with their support and wisdom. We also learn about the history of the Vice Presidency, an office that eventually evolved into five regional Vice Presidencies from across the United States. Another chapter focuses on the ongoing changes to the association’s By-Laws/Constitution with detailed explanations on why each change was necessary. We also find out about the creation of the logo, the crest and the certificates, ranging from when they were fashioned by hand through their current reproduction by computer. The motto, slogan and the special induction ritual have also been under scrutiny and revision over the years. Del Mastro reports the details elegantly with even the amusing but impractical suggestion by one member that the ritual follow the adventures of Don Quijote (120). The chapter on the Triennial Meetings is the second lengthiest in the book (the longest deals with the national presidents). Initially these meetings were held in conjunction with the MLA and AATSP conventions, first when they met jointly, then with just the MLA when the two larger organizations separated, and finally exclusively with the AATSP, with whom Sigma Delta Pi has become increasingly affiliated. The detailed accounts...

Sigma Delta Pi and the AATSP: A Shared Century of Leadership and Collaboration

Sigma Delta Pi and the AATSP: A Shared Century of Leadership and Collaboration

Editor’s Message: Revisiting Writers and their Fiction

Editor’s Message: Revisiting Writers and their Fiction Sheri Spaine Long, Editor Last December, Hispania featured its first State-of-the-State article on the linguistic topic of aspect or tense (see Hispania 96.4 [2013]: 624–39). Taking into account past research and publication on selected topics, the goal of the State-of-the-State feature is to advocate for an up-to-date and comprehensive perspective on the topic whether it is literary, linguistic, or pedagogical. For this current issue, I invited Mark P. Del Mastro (see his bio below) to pen an introductory essay to his featured article, titled “Reflections of Oneself: Reconciling Identity in Carmen Laforet’s Al volver la esquina.” Dr. Del Mastro points out the urgency of reevaluating the contributions of Spanish novelist Carmen Laforet in particular. It is worth considering this issue raised by Del Mastro with an even broader lens; over the last decade we have lost contact with an important living generation of writers on both sides of the Atlantic. Laforet died in 2004, and, this year, we lost other seminal novelists, such as Gabriel García Márquez (see Hispania 97.3 (2014): 351–54) and, more recently, Ana María Matute (see “Announcements” at the beginning of this issue). As students and critics of literary and cultural production, these milestones alert us to the timeliness of redoubling our efforts to review and reframe the work of such novelists with whom many of us were grateful to have shared a cup of coffee. Mark P. Del Mastro Mark P. Del Mastro (PhD, University of Virginia) is Professor and Chair of Hispanic Studies at the College of Charleston, and among his publications he has several articles on Carmen Laforet. He is also Executive Director of Sigma Delta Pi, the National Collegiate Hispanic Honor Society, and Founding Director of the South Carolina Spanish Teacher of the Year program. [End Page 551] Sheri Spaine Long, Editor Hispania Copyright © 2014 American Association of Teachers of Spanish and Portuguese, Inc

The measurement of permeability in single rat venules using the red cell microperfusion technique

The red cell microperfusion-micro-occlusion technique has been used to measure fluid filtration and reabsorption (Jv/A) at known microvascular pressures (Pc) in single mesenteric venules of anaesthetized rats. The relation between Jv/A and Pc is linear over the range of Pc from 15 to 50 cmH2O and its slope is the hydraulic permeability, Lp. Reproducible estimates of Lp can be made in the same venule in separate microperfusions. The value of Pc at Jv/A = 0 varies linearly with perfusate oncotic pressure and is the effective oncotic pressure of the perfusate, sigma delta pi, when the hydrostatic pressure in the pericapillary fluid is zero. The mean value for Lp (+/- S.E.M.) in forty venules was 2.43 (+/- 0.2) x 10(-7) cm s-1 cmH2O-1. Two potential errors of the micro-occlusion technique (vessel distensibility and marker red cell size) were investigated. It was found that the effects of vessel distensibility had little effect on red cell movements at times later than 2 s after a step change in Pc. Red cell size had a potentially large effect on estimates of the absolute values of Lp. Cooling the mesenteric tissues from 37 to 7 degrees C reduced Lp in proportion to the change in the reciprocal of water viscosity with temperature. Rat venular permeability was shown to be sensitive to histamine, with Lp increasing and sigma delta pi falling in a concentration-dependent fashion with histamine concentrations of 1.6 x 10(-5) to 3.3 x 10(-4) mol l-1 in the perfusate.

Effects of hydroxyethylrutosides on the permeability of microvessels in the frog mesentery

1. We have investigated the effects of a standardised mixture of hydroxyethylrutosides (HR, Venoruton), a mixture of five of its main components (M) and each of the five components separately (7-mono-HR, 7,4'-di-HR, 7,3',4'-tri-HR, 5,7,3',4'-tetra-HR and 7,3'4'-tri HQ) upon the permeability of single perfused capillaries and venules in the mesenteries of pithed frogs. 2. In each experiment, the hydraulic permeability (Lp) of a single perfused microvessel and the effective osmotic pressure (sigma delta pi) exerted by macromolecules across its walls were estimated by a microcclusion technique, first during control perfusion and then in the presence of a known concentration of test substance. 3. HR, M and 7,4'-di-HR reduced Lp in a similar concentration-dependent manner over the range of 1 microgram ml-1 to 1 mg ml-1 (maximum reduction was to 40% of control Lp at 1 mg ml-1). At perfusate concentrations greater than 1 mg ml-1, these substances reduced Lp to a lesser extent. While the four other test substances reduced Lp significantly when their perfusate concentrations equalled or exceeded 100 micrograms ml-1, they were all less potent than 7,4'-di-HR. 4. The reduction in Lp induced by the mixture of flavonoids was only slightly reversed by subsequent perfusion with flavonoid-free solutions. 5. When permeability was increased by perfusing with protein-free solutions, both HR and 7,4'-di-HR reduced and then reversed the increase in Lp in a concentration-dependent manner over the range of 1 microgram ml-1 to 100 micrograms ml-1. None of the other component flavonoids was effective in restoring Lp under these conditions.

Enhanced fluid uptake in frog mesenteric capillaries associated with plasmin perfusion.

1. We have measured the permeability of single capillaries of the mesenteries of decerebrated frogs, before and during perfusion with solutions containing the fibrinolytic enzyme, plasmin. 2. The hydraulic permeability (Lp) and the effective oncotic pressure exerted across the vessel walls (sigma delta pi) were measured using the method of Michel (1980). The vessels were sequentially perfused with a control frog Ringer solution containing either Ficoll 70 or bovine serum albumin (BSA) at concentrations of 40 mg ml-1 or a mixture of Ficoll 70 (40 mg ml-1) and BSA (10 mg ml-1), and then with a second Ringer perfusate containing plasmin (1 mg ml-1) but in all other respects identical to the control solution. 3. In sixteen out of seventeen experiments, perfusion with plasmin increased sigma delta pi. In eleven of these experiments the increase was very large such that sigma delta pi exceeded the in vitro value for perfusate oncotic pressure. 4. In the same seventeen vessels plasmin perfusion was associated with a fall in Lp from a mean value of 10.3 x 10(-7) cm s-1 cmH2O-1 to one of 7.7 x 10(-7) cm s-1 cmH2O-1. The fall in Lp was not significant. 5. In five of the seventeen vessels, a second control perfusion was made after exposure to plasmin. There was no evidence that Lp had increased above or sigma delta pi had fallen below the initial control value. 6. In a further six experiments, the effects of plasmin were investigated in the absence of other perfusate macromolecules. No significant changes in Lp or sigma delta pi were observed. 7. In a further eight vessels, the effects of plasmin on fluid filtration were investigated with the tissues cold and then at room temperature. In all eight vessels plasmin reduced filtration or increased fluid reabsorption to a greater extent when the tissue temperature was 17 degrees C than when it was 4 degrees C. 8. The large increases in sigma delta pi which we have observed during perfusion of single vessels with plasmin-containing solutions are consistent with the development of substantial local osmotic gradients at the capillary wall following the enzyme's action upon substrates at the endothelial cell surface, one of which could be fibrin. Alternatively, plasmin might stimulate endothelial cells to liberate molecules which locally amplify the oncotic pressure exerted by the perfusate macromolecules. These effects are more marked at room temperature than at 4 degrees C.

Effects of hydroxyethyl rutosides upon the permeability of single capillaries in the frog mesentery.

1. We have investigated the effects of a standardised mixture of hydroxyethyl rutosides (HR) upon the permeability of the walls of single capillaries and venules of the frog mesentery. 2. In each experiment a single vessel was perfused via a micropipette with frog Ringer solutions containing bovine serum albumin (10 mg ml-1) and Ficoll 70 (40 mg ml-1) first in the absence of HR and then with HR added to the perfusate. The permeability of the vessel walls was assessed during each perfusion by using a development of the Landis micro-occlusion technique to estimate their hydraulic permeability (Lp) and the effective osmotic pressure (sigma delta pi) exerted across them by the perfusate macromolecules. 3. Measurements were made both in vessels which appeared to be healthy and in vessels showing signs of stasis or inflammation before perfusion. 4. HR at concentrations of 1.0, 0.1 and 0.01 mg ml-1 reduced hydraulic permeability to approximately half of its value in the absence of HR. It increased sigma delta pi to macromolecules at concentrations of 10, 1.0, 0.1, 0.01 and 0.001 mg ml-1. The effects of HR upon permeability were not reversed within 10 min of perfusion with an HR-free solution. 5. Ultrastructural examination of a number of vessels in which initial high values of permeability were reduced to values within the normal range of permeabilities by HR, showed clear signs of damage to the endothelium, with large gaps between adjacent endothelial cells. 6. These observations suggest that HR does reduce microvascular permeability both in healthy vessels and vessels showing of inflammation. The reduction in permeability of inflamed vessels does not appear to be the result of closure of the gaps between adjacent endothelial cells.

THE EFFECTS OF IONOPHORE A23187 ON PERMEABILITY OF THE FROG MESENTERY MICROVASCULATURE

The effects of the divalent cation ionophore A23187, upon microvascular permeability have been investigated in single perfused capillaries and venules in the mesenteries of pithed frogs. In all experiments, the vessels were perfused with Ringer solutions containing the macromolecules Ficoll 70 (40 mg ml-1) and bovine serum albumin (10 mg ml-1). Hydraulic permeability (Lp) of the vessel walls and the effective osmotic pressure (sigma delta pi) exerted across them by the perfusate macromolecules were estimated by the method of Michel (1980). In eleven experiments addition of A23187 to the perfusate raised Lp from a mean value (+/- S.E.M.) of 4.76 (+/- 1.05) x 10(-7) cm s-1 cmH2O-1 to one of 11.97 (+/- 1.96) x 10(-7) cm s-1 cmH2O-1 and reduced sigma delta pi from a mean (+/- S.E.M.) of 16.5 (+/- 2.01) cmH2O to one of 7.6 (+/- 1.93) cmH2O. The effects of A23187 on Lp and sigma delta pi were reversible. A23187 was found to increase Lp and reduce sigma delta pi after the mesentery had been exposed to compound 48/80 to degranulate the mast cells two or more hours previously. A23187 also appeared to be effective in raising Lp and lowering sigma delta pi in the absence of Ca2+ ions from the perfusate and superfusate. The ionophore was found to reduce permeability, however, when Mg2+ ions were removed from the perfusate and superfusate both in the absence and in the presence of Ca2+. This reduction in permeability could be converted into an increase in Lp and fall in sigma delta pi if Mg2+ were restored to the superfusate. It is concluded that A23187 increases vascular permeability in a reversible manner and that Mg2+ ions in the extracellular fluids are necessary for its action.

Inflammatory changes in permeability and ultrastructure of single vessels in the frog mesenteric microcirculation.

1. In fifteen experiments, single microvessels in the exposed mesenteries of pithed frogs were perfused with Ringer solutions containing bovine serum albumin (40 mg ml-1). For each vessel, the hydraulic permeability of its walls (Lp) and effective osmotic pressure exerted across them (sigma delta pi) were determined from measurements of fluid filtration rates at two capillary pressures (Michel, Mason, Curry, Tooke & Hunter, 1974) before and at predetermined times after the tissue temperature had been raised abruptly from approximately 15 degrees C to 30-35 degrees C. Temperatures greater than 30 degrees C appear to damage the tissues of frogs acclimatized to temperatures of 5-10 degrees C. 2. In fourteen out of fifteen experiments Lp rose when the temperature was raised to 30-35 degrees C. In twelve of these experiments the increase in Lp was greater than expected from the fall in water viscosity with temperature, and was progressive. In five vessels where measurements were made 1-2 min after tissue temperature was raised, Lp increased from an initial mean value (+/- S.E.M.) of 3.76 (+/- 0.54) x 10(-3) micron s-1 cmH2O-1 to one of 8.72 (+/- 1.68) x 10(-3) micron s-1 cmH2O-1. In nine vessels where measurements were made at 10 min after tissue temperature was raised, Lp increased from an initial mean value of 4.03 (+/- 0.72) x 10(-3) micron s-1 cmH2O-1 to one of 16.9 (+/- 3.5) x 10(-3) micron s-1 cmH2O-1. Further increases in Lp were seen at 15 and 20 min. 3. The changes in the effective osmotic pressure opposing filtration, sigma delta pi, were very variable. Out of the twelve vessels which showed large changes in Lp with tissue heating, four showed no reduction in sigma delta pi after 10 min, though sigma delta pi fell in three of these vessels at 15 min. In the other eight vessels, sigma delta pi fell as Lp rose. A quantitative theory developed in this paper allowed the changes in sigma delta pi to be analysed in terms of a component across the regions of vessel wall of increased permeability (sigma H delta pi H) and a component across regions where Lp was unchanged. In six vessels sigma H delta pi H approximated to zero; in two vessels sigma H delta pi H was 6.2 and 4.5 cmH2O.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of chemical fixation on the permeability of frog mesenteric capillaries.

1. We have investigated the effects on microvascular permeability of two chemical fixatives, glutaraldehyde/formaldehyde mixture and osmium tetroxide, both of which are used widely in electron microscopy. 2. The permeability of single perfused frog mesenteric capillaries was assessed using the technique of Michel (1980) to estimate the hydraulic conductance (Lp) of the vessel walls and the effective osmotic pressure (sigma delta pi) which could be exerted across them by the neutral macromolecule, Ficoll 70. 3. In each experiment, Lp and sigma delta pi were estimated in the same capillary before and after chemical fixation with either an aldehyde mixture (n = 6) or 1% osmium tetroxide (n = 6). In the absence of serum proteins in the perfusate, the values of Lp recorded prior to fixation were high. The effect of both fixatives was to reduce Lp. With aldehydes the mean value (+/- S.E.M.) of Lp fell from 22.1 (+/- 6.3) x 10(-3) to 5.7 (+/- 2.0) x 10(-3) microns s-1 cmH2O-1. With osmium tetroxide the mean Lp fell from 29.1 (+/- 8.5) x 10(-3) to 8.6 (+/- 3.6) x 10(-3) microns s-1 cmH2O-1. 4. The perfusates contained the neutral macromolecule, Ficoll 70, at a concentration of 60 mg ml-1 which exerted an osmotic pressure of 35 cmH2O in a membrane osmometer. In the absence of plasma proteins in the perfusate, sigma delta pi was only a fraction of this perfusate oncotic pressure prior to fixation. After aldehyde treatment there was a small but insignificant decrease in sigma delta pi. Osmium tetroxide, however, increased sigma delta pi from a mean (+/- S.E.M.) of 6.3 (+/- 1.6) cmH2O before fixation to 16.4 (+/- 2.8) cmH2O after fixation, P less than 0.01 using a paired t test. 5. In three experiments, the reflection coefficient of the capillary wall to NaCl sigma NaCl, was measured using the technique of Curry, Mason & Michel (1976) before and after osmium fixation. Fixation raised sigma NaCl from a mean value (+/- S.E.M.) of 0.009 (+/- 0.001) to one of 0.017 (+/- 0.004). Although these changes may be interpreted as an increase in the contribution to the total Lp of the capillary wall of channels which are available only to water, the changes are too small for such a mechanism to account for the increase in reflection coefficient to Ficoll 70. 6. The reduction in Lp following chemical fixation could represent an increase in the hydraulic resistance of either the capillary wall itself, or in the tissues surrounding the vessel.(ABSTRACT TRUNCATED AT 400 WORDS)

The Spanish National Honor Society, Sigma Delta Pi

The Spanish National Honor Society, Sigma Delta Pi