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N A Mortillaro

Publications and source records attributed to N A Mortillaro.

15 recordsLinked to original sources
PubMed1990

Lectures in physiology: a three-phase evaluation plan.

The initial phase of a voluntarily implemented multiphasic plan for improving faculty lectures was completed in 1988 and reported in 1989 [Am. J. Physiol. 256 (Adv. Physiol. Educ. 1): S3-S8, 1989]. That phase, conducted by a teaching consultant, included analysis of the teaching practices of each of seven faculty members. Following lecture observations, each faculty member received a written critique of his/her teaching, and individual as well as departmental strengths and weaknesses were identified. In the 1989 follow-up phase, faculty reviewed the feedback provided in their critiques and attended a seminar on developing effective lectures. Each faculty member was again observed during the presentation of a lecture; the same observation instrument was used in the follow-up phase as was used in the initial phase. A comparative analysis of the 1988 and 1989 teaching behaviors was completed for each faculty member and for the whole department. Results indicate that definitive changes had occurred in teaching methods employed since the initiation of the plan. Additional recommendations were made and specific target areas for ongoing improvement were identified.

Alabama↗
PubMed1990

Microvascular permeability to endogenous plasma proteins in the jejunum.

Steady-state lymph flow and lymph (CL) and plasma (CP) protein concentrations were measured at venous outflow pressures of 0, 10, 20, and 30 mmHg in an autoperfused segment of cat jejunum. In addition to determining total protein concentrations in lymph and plasma, polyacrylamide gradient gel electrophoresis was used to determine lymph and plasma protein concentrations of albumin and nine other plasma proteins. The osmotic reflection coefficient (sigma d) for total proteins, albumin, and each of the nine protein fractions was estimated using CL/CP at a capillary filtration rate independent state, when 1 - CL/CP = sigma d. A sigma d of 0.83 was obtained for total proteins, a value similar to that reported for both dog jejunum and descending colon (0.85) but appreciably different from that reported for both cat stomach (0.78) and ileum (0.92). Additionally, sigma d for albumin and each of the nine plasma protein fractions (molecular radii ranging from 37 to 120 A) increased as molecular radius increased. A two-pore model composed of a ratio of 3,750 48-A radius small pores to one 250-A radius large pore describes the data obtained, with 82% of the total volume flow occurring through the small pores and 16% through the large pores.

Animals↗
PubMed1989

Teaching effectiveness analysis plan applied to lectures in medical physiology.

To improve and thus strengthen its teaching program, the Department of Physiology at the University of South Alabama voluntarily embarked on a multiphasic self-assessment of its medical teaching program. One phase of the greater assessment plan included an analysis of the teaching methods of each faculty member. To design and implement this phase, the services of a teaching consultant from the College of Education were obtained. The implementation of the objectives as established by the consultant resulted in 1) the development of a systematic and consistent method of evaluating the teaching practices of the faculty through the design of a standard observation instrument for use in analyzing the teaching of each individual; 2) the sampling of the teaching of each of the seven participating faculty members; 3) the collection and critical review of teaching materials used; 4) an analysis of the effectiveness of the faculty; and 5) the submission of a written report of evaluation results. The seven participating faculty members were observed during the delivery of two lectures each presented to the freshman medical class. Based on the analysis of both the lectures and materials used, a written critique of each faculty member was submitted. Lecture strengths and weaknesses, both of individual members and of the whole department were summarized. Finally, the results of a survey taken of the faculty in which the participants were asked to respond to a series of questions regarding the self-assessment program were most favorably accepted by all participating faculty.

Alabama↗
PubMed1989

Interstitial fluid pressure of ileum measured from chronically implanted polyethylene capsules.

Steady-state fluid pressure measurements were obtained from polyethylene capsules chronically implanted in the walls of cat ileum. Measurements were performed while ileal venous outflow pressure was maintained at 0, 10, 20, or 30 mmHg. The resulting mean steady-state capsule pressure ranged from -0.56 to 7.3 mmHg over the range of imposed venous outflow pressures. The data provide evidence that at an ileal venous outflow pressure in the range of 10 mmHg, comparable to a normal portal pressure, interstitial fluid pressure is positive, increasing as tissue hydration increases, and is a significant contributing force opposing increases in the transcapillary filtration force. Additionally, the qualitative response of implanted capsules to close intra-arterial infusion of normal saline (transcapillary filtration), Dextran 40 (transcapillary absorption), and histamine (transcapillary filtration-permeability changes), and during and after an arterial occlusion of 60-s duration (transcapillary absorption-filtration) were obtained. The results demonstrate that the implanted capsules appropriately track changes in interstitial fluid pressure when the state of tissue hydration is altered by an induced net transcapillary fluid filtration or absorption. Finally, total protein concentration of capsule fluid was not significantly different from lymph fluid derived from a lymphatic vessel draining the ileal segment.

Animals↗
PubMed1987

Segmental vascular resistances and compliances in dog lung.

The segmental distribution of vascular resistances and compliances were evaluated in isolated blood perfused lung lobes using arterial, venous, and double-occlusion pressures and were compared with filtration midpoint capillary pressures (Pc,f). We separated total vascular resistance (RT) and compliance (CT) into large artery (Ra, Ca), large vein (Rv, Cv), and microvascular compartments (Rmc, Cmc) at base-line and increased vascular pressures and during infusions of histamine, serotonin, and norepinephrine. In control lobes, double-occlusion pressure (Pdo) closely approximated Pc,f at all vascular pressures. Pre- and postcapillary resistance were approximately equal when referenced to either Pc,f or Pdo. Although Rmc comprised 42% of RT and Cmc constituted 76% of CT, a twofold increase in base-line Pc,f caused RT to decrease to 67% and Rmc/RT to 29% of control values, whereas CT decreased to 87% and Cmc/CT decreased to 88% of control values over the same Pc,f range. Mean static CT was 2.25 +/- 0.09 ml X cmH2O-1. 100 g-1, whereas dynamic CT was 1.54 +/- 0.08 ml X cmH2O-1. 100 g-1, or only 68% of static vascular compliance. Drug infusions increased mean RT from 4.2- to 5.3-fold and significantly decreased both static and dynamic CT. Although all vascular segments were constricted, histamine affected primarily large veins, serotonin increased Ra greater than Rv, and norepinephrine constricted upstream and downstream vessels about equally. Increased Pc,f in the presence of these drugs decreased RT significantly in every case primarily through attenuation of the drug vasoconstrictor effect on Rmc and decreased CT primarily due to a decrease in Cmc, but increased Cmc/(Ca + Cv). Thus the microvascular compartment appears to be the major site of both fluid filtration and vascular compliance and contributes significantly to total vascular resistance. Drug infusions constricted large and small vessel compartments as defined here, but increased Pc,f attenuated microvascular vasoconstriction and to a lesser extent large vessel vasoconstriction resulting in a reduced microvascular resistance in both drug-treated and control lobes. This effect can be attributed to recruitment and/or distension of microvessels and distension of larger vessels.

Animals↗
PubMed1982

Autoregulation of intestinal capillary filtration rate.

To determine whether intestinal capillary filtration rate, capillary pressure, or both are autoregulated in the cat ileum, the following parameters were measured under isovolumetric conditions: lymph flow, capillary pressure, capillary filtration coefficient, and lymph and plasma oncotic pressures. Superior mesenteric arterial pressure was reduced in 25-mmHg steps from 125 to 25 mmHg. As arterial pressure was reduced, lymph flow, capillary pressure, and the transcapillary oncotic pressure gradient decreased while the capillary filtration coefficient increased. Over the arterial pressure range of 75-125 mmHg, capillary pressure decreased in a fashion expected from a rigid system; however, capillary pressure was slightly autoregulated at lower arterial pressures. Lymph flow fell proportionately more than capillary pressure over the entire arterial pressure range. The results of this study indicate that intestinal capillary pressure and capillary filtration rate are poorly autoregulated in the cat when arterial pressure is reduced. Changes in interstitial fluid pressure play a major role in preventing interstitial dehydration in the cat ileum when arterial pressure is reduced.

Animals↗
PubMed1981

Effects of histamine and histamine antagonists on intestinal capillary permeability.

Steady-state lymph flow, blood flow, and lymph and plasma total protein concentration were measured in an autoperfused cat ileum preparation during the continuous infusion of histamine at venous pressures of 0, 10, 20, and 30 mmHg. The capillary osmotic reflection coefficients for total proteins and each protein fraction were estimated. In addition, the ileum was pretreated with an H1-receptor antagonist (diphenhydramine) or with an H2-receptor antagonist (cimetidine). The results suggest that histamine selectively increases the ileal vascular permeability to plasma proteins of a molecular radius up to 96 A. The H1-receptor antagonist did not alter the histamine-induced permeability changes but did block the observed initial vasodilation. The H2-receptor antagonist significantly reduced the permeability changes associated with histamine while having only a slight effect on the initial vasodilation. It is concluded that the activation of H1-receptors is predominantly associated with the initial vasodilation, whereas the H2-receptors are predominantly associated with permeability.

Animals↗
PubMed1980

Role of the interstitial matrix during intestinal volume absorption.

The effects of net volume absorption rate (Jv,m) on intestinal interstitial fluid volume (VI), lymph flow (JL), and the excluded volume fraction for interstitial albumin (FE) were analyzed in an autoperfused cat ileum preparation. Tissue blood volume, extracellular space, and extracellular albumin (VA) were estimated using 51Cr-labeled red blood cells, 99mTc-labeled diethylenetriamine pentaacetic acid (DTPA), and 125I-labeled human serum albumin, respectively. Nonabsorptive values of 27.8 ml/100 g, 18.2 ml/100 g, and 0.37 were acquired for VI, VA, and FE, respectively. Net volume absorption results in an increase in intestinal interstitial volume and lymph flow and decreases the degree of albumin exclusion in the interstitial matrix. The magnitude of the changes in interstitial volume, lymph flow, and excluded volume of albumin during net volume absorption are related to the rate of absorption. The increased matrix hydration during absorption serves to enchance vascular and lymphatic removal of absorbed volume.

Animals↗
PubMed1980

Mechanism of glucagon-induced intestinal secretion.

The effects of local intra-arterial glucagon infusion on transcapilary, lymphatic, and transmucosal fluid and protein fluxes were studied in autoperfused segments of cat ileum. The glucagon infusions resulted in a significant increase in intestinal blood flow, lymph flow, capillary filtration coefficient, capillary pressure, interstitial volume, and interstitial fluid pressure. Precapillary resistance and the pre-to-postcapillary resistance ratio decreased during the glucagon infusion. The transcapillary oncotic pressure gradient and the osmotic reflection coefficient were reduced, suggesting that capillary permeability is significantly increased with glucagon. Ultrastructural analysis of tissue samples acquired during the infusion of higher doses of glucagon indicates disruption of the mucosal membrane. An glucagon indicates disruption of the mucosal membrane. An alteration in mucosal structure is supported by the appearance of plasma proteins in the secreted fluid. The results of this study indicate that glucagon-induced intestinal secretion results from an alteration in capillary fluid balance, i.e., an increased capillary pressure and permeability.

Animals↗
PubMed1980

Effect of luminal distension on intestinal transcapillary fluid exchange.

The direct effects of luminal distension pressure on intestinal transcapillary fluid exchange were studied in isolated autoperfused cat ileum preparations. Intestinal lymph flow, lymphatic pressure, lymph-to-plasma protein concentration ratio (L/P), blood flow, and perfusion pressures were allowed to reach a steady state at different luminal distension pressures (0-40 mmHg). Luminal distension was induced using a nonabsorbable silicone solution, thereby eliminating an influence of net water absorption. At a venous outflow pressure of 0 mmHg, lymph flow and lymphatic pressure increased, whereas blood flow and L/P decreased as luminal pressure was increased. The relationship between lymph flow, blood flow, and venous pressure was acquired at luminal pressures of 0 and 20 mmHg. When luminal pressure was 0, lymph flow increased and blood flow decreased progressively with venous pressure elevation; however, when luminal pressure was 20 mmHg, lymph flow and blood flow were unaffected until pressure exceeded 20 mmHg. The results of this study indicate that luminal pressure elevation enhances transcapillary fluid exchange and imposes a "waterfall" effect on the intestinal vasculature.

Animals↗
PubMed1977

Interactions of intestinal lymph flow and secretion.

The relationship between lymph flow and intestinal secretion was studied in an isolated, vascularly perfused cat ileal preparation in which secretion was caused by three different means: 1) plasma dilution from a constant infusion of Tyrode solution (2.5 ml/min per kg), 2) elevation of intestinal venous pressure to 30 mmHg, and 3) exposure to cholera toxin. In the plasma-dilution group, lymph flow attained a peak value of 38 times control at 60-90 min following the onset of the infusion, after which time lymph flow progressively decreased. Concomitant to the rapid decrease in lymph flow was a rapid increase in intestinal secretion (filtration secretion). A similar pattern, i.e., a rapid increase in lymph flow followed by a progressive decrease in lymph flow and concomitant increase in filtration secretion, was observed in the venous hypertension group; however, peak lymph flow (20 X control) was observed within 10 min of the pertubation. No correlation between the onset of intestinal secretion and a decline in lymph flow was observed in the cholera toxin group.

Animals↗
PubMed1976

Interaction of capillary and tissue forces in the cat small intestine.

We measured steady state capillary hydrostatic pressure (P c,i), plasma and lymph protein concentrations, lymph and blood flow, and capillary filtration coefficients in an in situ loop of cat small intestine at venous outflow pressures (PV) of 0, 5, 10, 15, 20, 25, and 30 mm Hg. The data were used to calculate colloid osmotic pressure of lymph and plasma, interstitial fluid pressure (Pt), pre- and postcapillary resistances, and a tissue pressure-volume curve of the intestinal interstitium. When PV was elevated from 0 to 30 mm Hg, lymph protein concentration decreased from 3.8 to 1.9 g/100 ml (representing a change in colloid osmotic pressure of 6.2 mm Hg), lymph flow increased 7-fold (or an equivalent imbalance in Starling forces of 4.3 mm Hg), and the calculated PT increased from 1.8 to +5.3. Because lymph flow draining the loop decreased during the determination of Pc, i at venous pressures between 15 and 30 mm Hg, the corresponding calculated PT may be in error by 1-2 mm Hg. The tissue pressure-volume relationship calculated from the data indicates that the intestinal interstitial volume expands nonlinearly and this expansion is characterized by two distinctly different compliant components: (1) tissue compliance is low at PV between 0 and 15 mm Hg (0.4 ml/mm Hg), and (2) at PV greater than 15 mm Hg the tissue compliance is relatively high (4 ml/mm Hg). We found that when PV was elevated from 0 to 15 mm Hg, increases in PT are the major tissue adjustments that oppose the increased filtration pressures. Furthermore, at Pv of 20-30 mm Hg, tissue protein concentration decreases, lymph flow relative to the filtration coefficient (deltaP DROP) increases and, to a much lesser extent, PT increases. Finally, the combination of these changes in tissue force at high filtration pressures represent a maximum tissue edema "safety factor" of 10 mm Hg; further increases in filtration pressures result in large volume movements into the intestinal lumen.

Animals↗