Biofield therapies: Guidelines for reporting clinical trials

A set of guidelines has been developed to help improve reporting of clinical trials of biofield therapies. The need for enhanced transparency when reporting trials of this family of integrative health practices, e.g., External Qigong, Healing Touch, Reiki and Therapeutic Touch, has been advocated in systematic reviews of these studies. The guidelines, called Biofield Therapies: Reporting Evidence Guidelines (BiFi REGs), supplement CONSORT 2010 by including details of the intervention protocols relevant to biofield therapy trials. BiFi REGs evolved through a draft document created by a core group, two rounds of a Delphi process with an international group of subject matter experts and two panels, meeting via Zoom, which included editors of complementary and integrative medicine journals. BiFi REGs comprises a 15-item Intervention checklist. Modifications of two other CONSORT topic areas are also proposed to enhance their relevance to trials of biofield therapies. Included for each item are an explanation, and exemplars of reporting from peer-reviewed published reports of biofield therapy trials. When used in conjunction with all other items from CONSORT 2010, we anticipate that BiFi REGs will expedite the peer review process for biofield therapy trials, facilitate attempts at trial replication and help to inform decision-making in the clinical practice of biofield therapies.

Biofield therapies: Guidelines for reporting clinical trials

A set of guidelines has been developed to help improve reporting of clinical trials of biofield therapies. The need for enhanced transparency when reporting trials of this family of integrative health practices, e.g., External Qigong, Healing Touch, Reiki and Therapeutic Touch, has been advocated in systematic reviews of these studies. The guidelines, called Biofield Therapies: Reporting Evidence Guidelines (BiFi REGs), supplement CONSORT 2010 by including details of the intervention protocols relevant to biofield therapy trials. BiFi REGs evolved through a draft document created by a core group, two rounds of a Delphi process with an international group of subject matter experts and two panels, meeting via Zoom, which included editors of complementary and integrative medicine journals. BiFi REGs comprises a 15-item Intervention checklist. Modifications of two other CONSORT topic areas are also proposed to enhance their relevance to trials of biofield therapies. Included for each item are an explanation, and exemplars of reporting from peer-reviewed published reports of biofield therapy trials. When used in conjunction with all other items from CONSORT 2010, we anticipate that BiFi REGs will expedite the peer review process for biofield therapy trials, facilitate attempts at trial replication and help to inform decision-making in the clinical practice of biofield therapies.

Biofield Therapies: Guidelines for Reporting Clinical Trials

Highlights Guidelines have been created to improve the reporting of clinical trials of biofield therapies, e.g. External Qigong, Healing Touch, Reiki, and Therapeutic Touch. Appropriate use of these guidelines is likely to strengthen the evidence base for biofield therapies as well as increase their usage as stand-alone practices and as complementary therapies within mainstream healthcare.

Biofield Therapies: Guidelines for Reporting Clinical Trials

A set of guidelines has been developed to help improve reporting of clinical trials of biofield therapies. The need for enhanced transparency when reporting trials of this family of integrative health practices, eg, External Qigong, Healing Touch, Reiki and Therapeutic Touch, has been advocated in systematic reviews of these studies. The guidelines, called Biofield Therapies: Reporting Evidence Guidelines (BiFi REGs), supplement CONsolidated Standards of Reporting Trials (CONSORT) 2010 by including details of the intervention protocols relevant to biofield therapy trials. BiFi REGs evolved through a draft document created by a core group, two rounds of a Delphi process with an international group of subject matter experts and two panels, meeting via Zoom, which included editors of complementary and integrative medicine journals. BiFi REGs comprises a 15-item Intervention checklist. Modifications of two other CONSORT topic areas are also proposed to enhance their relevance to trials of biofield therapies. Included for each item are an explanation, and exemplars of reporting from peer-reviewed published reports of biofield therapy trials. When used in conjunction with all other items from CONSORT 2010, we anticipate that BiFi REGs will expedite the peer review process for biofield therapy trials, facilitate attempts at trial replication and help to inform decision-making in the clinical practice of biofield therapies.

Erratum: General Theory of Inflammation: Patient Self-Administration of Hydrocortisone Safely Achieves Superior Control of Hydrocortisone-Responding Disorders by Matching Dosage with Symptom Intensity [Corrigendum]

[This corrects the article DOI: 10.2147/JIR.S195165.].

Evaluation of a Distance Reiki Program for Frontline Healthcare Workers' Health-Related Quality of Life During the COVID-19 Pandemic

Background

Reiki is a biofield therapy which is based on the explanatory model that the fields of energy and information of living systems can be influenced to promote relaxation and stimulate a healing response.

Objective

To conduct a pragmatic within-subject pilot trial of a remote Reiki program for frontline healthcare workers' health-related symptoms during the COVID-19 pandemic.

Methods

Healthcare professionals in the UK (eg, physicians, nurses, and paramedics) were eligible to sign up for a distance Reiki program and were also invited to participate in the research study. Eight Reiki practitioners simultaneously gave each participant Reiki remotely for 20 minutes on 4 consecutive days. Feasibility of the research was assessed, including recruitment, data completeness, acceptability and intervention fidelity, and preliminary evaluation of changes in outcome measures. Participants' stress, anxiety, pain, wellbeing, and sleep quality were evaluated with 7-point numerical rating scales. Measures were completed when signing up to receive Reiki (pre) and following the final Reiki session (post). Pre and post data were analyzed using Wilcoxon signed ranks tests.

Results

Seventy-nine healthcare professionals signed up to receive Reiki and took the baseline measures. Of those, 40 completed post-measures after the 4-day intervention and were therefore included in the pre-post analysis. Most participants were female (97.5%), and the mean age was 43.9 years old (standard deviations = 11.2). The study was feasible to conduct, with satisfactory recruitment, data completeness, acceptability, and fidelity. Wilcoxon signed ranks tests revealed statistically significant decreases in stress (M = -2.33; P < .001), anxiety (M = -2.79; P < .001) and pain (M = -.79; P < .001), and significant increases in wellbeing (M = -1.79; P < .001) and sleep quality (M = -1.33; P = .019).

Conclusions

The Reiki program was feasible and was associated with decreased stress, anxiety and pain, and increased wellbeing and sleep quality in frontline healthcare workers impacted by the COVID-19 pandemic.

An Evaluation of the Subjective Experience of Receiving Reiki: Qualitative Results from a Pragmatic Effectiveness Study

Objectives: The main purpose of this study was to evaluate the subjective experience of Reiki in a large sample. Design: The study design was a single-arm pragmatic effectiveness trial with qualitative questions completed post-Reiki session. Setting: The study took place at private Reiki practices across the United States. Subjects: A total of 99 Reiki practitioners met the inclusion criteria and participated in the study. Reiki practitioners invited each of their Reiki clients to complete a survey before and after the Reiki session. Of the N = 1575 Reiki sessions recorded, N = 1284 qualitative responses were completed (82% of total) and included in the analysis. Interventions: Trained and experienced Reiki masters conducted Reiki sessions in person, with each session lasting between 45 and 90 min. Outcome measures: Participants were asked to describe their experience during the Reiki session. Results: Qualitative analysis revealed eight major themes: (1) deep relaxation and calm (68%), (2) body sensations/somatic experiences (53%), (3) emotions (29%), (4) spiritual or symbolic significance (18%), (5) changes in symptoms (17%), (6) changes in perception (11%), (7) sleep and drowsiness (10%), and (8) changes to breathing (4%). Significantly more males reported feeling relaxed and experiencing time perception changes, whereas more females reported body sensations, emotions, visual perceptions, and spiritual significance. Conclusions: The findings from this study suggest that Reiki can elicit the relaxation response and alter emotions and perception in such a way as to facilitate a transformative subjective healing experience. Future work will analyze these themes as they relate to changes in symptoms and compare the experience of Reiki with other biofield therapies.

General theory of inflammation: patient self-administration of hydrocortisone safely achieves superior control of hydrocortisone-responding disorders by matching dosage with symptom intensity

Objective: To determine if patient self-administration of hydrocortisone will safely achieve superior symptom control for all hydrocortisone-responding disorders as it does for Addison's disease and rheumatoid arthritis. Methods: Two thousand four hundred and twenty-eight participants with hydrocortisone-responding disorders were brought to a minimum symptom state using daily administered hydrocortisone tablets in a 24-week, open study. Thereafter, participants used 5-day, low-dose hydrocortisone regimens to quench subsequent disorder exacerbations (flares) to maintain the minimum symptom state. Stressors such as emotional traumas, infections, allergies, and injuries were minimized to reduce disorder intensity, hydrocortisone consumption, and participant discomfort. Results: Two thousand fifteen participants, 601 with fibromyalgia, 579 with osteoarthritis, 246 with rheumatoid arthritis, 226 with undifferentiated arthritis, 75 with back pain, 51 with Parkinson's disease, 44 with polymyalgia rheumatica, 25 with neuropathy, 25 with chronic fatigue syndrome, 25 with dementia, 21 with migraine headache, 19 with multiple sclerosis, and 78 with other disorders completed the 24-week study to achieve a composite average symptom improvement of 76% with equal response rates. The participants averaged ingesting 12 mg of hydrocortisone per day. No significant adverse reactions were observed. Conclusions: Patient self-administration of hydrocortisone safely achieves superior symptom control for 38 hydrocortisone-responding disorders at equal rates and symptom improvements to confirm and amplify an earlier double-blind study finding on rheumatoid arthritis. These results are consistent with the body having an inflammation control system and chronic inflammation being a disorder unto itself with differing symptoms sets dependent on its location. Clinical Trials Government Identifier: NCT03558971.

An Integrative Review of Scientific Evidence for Reconnective Healing

Background: Biofield therapies offer a novel, non-invasive approach to treating chronic diseases based on assessing and adjusting an individual's physiological and emotional responses through their bio-energetic field. Reconnective Healing^™ (RH) is defined as: “…not just energy healing, but instead a more comprehensive spectrum of healing composed of energy, light, and information.”

Objectives: Several biofield therapies, such as Reiki, Therapeutic Touch and Johrei, have already been reviewed in the literature but RH has received little attention even though it is taught and practiced worldwide. This review provides a critical assessment of RH as a healing modality.

Methods: Scientific research articles published in peer-reviewed journals addressing RH were identified using relevant databases and archives. Information was extracted from each article that met selection criteria for evaluation of quality of reporting and design. This review summarizes and critically evaluates the five currently published peer-reviewed research papers involving RH and assesses whether RH provides consistent physiological outcomes between the studies.

Results: These results, taken together, suggest: (i) exposure of a healer or healee to RH, either directly or indirectly, amplifies their degree of autonomic arousal and energy, (ii) RH can reduce pain and improve range of motion in people with shoulder limitations, and (iii) when individuals experience RH as a group, their autonomic nervous systems simultaneously show sudden similar responses consistent with the idea that RH is mitigated by entrainment of biofields.

Conclusions: Since these studies are extremely varied in design it is not possible at this point to reach conclusions about the general effectiveness of RH. More clinical and physiological research performed on different populations under a range of conditions is needed in order to support this healthcare approach.

Transient diffusion of albumin in aortic walls: effects of binding to medial elastin layers

The goal of this study was to measure diffusive transport of albumin through artery walls experimentally and to analyze the results theoretically, taking into account the binding of albumin to elastic lamellae. Segments of rabbit aorta were placed in solutions of fluorescently labeled albumin for periods of 30, 60, 90, and 120 min, and the distributions of fluorescence intensity through the arterial media were observed. On average, intensity increased almost linearly with time. Bands of high intensity were observed corresponding to elastin layers within the media. The temporal and spatial variations of intensity were compared with predictions of theoretical models, including effects of albumin binding and hindered diffusion resulting from the complex wall structure. Based on these analyses, it was concluded that the spatial distribution of free albumin within the media equilibrated relatively rapidly, and that the observed linear increase in intensity reflected gradual accumulation of albumin bound to medial elastin layers. The results imply that previous theoretical analyses, in which binding was neglected, substantially underestimated albumin diffusivity in the aortic wall. With respect to stent-associated delivery of inhibitors of vascular cell proliferation, the results suggest that albumin might serve as an “affinity vehicle” for drug delivery to the aorta, by attaching the drug to an abundant component of the artery wall.

Knockout mice: is it just genetics? Effect of enriched housing on fibulin-4(+/-) mice

BACKGROUND

Fibulin-4 is an extracellular matrix protein expressed by vascular smooth muscle cells that is essential for maintaining arterial integrity. Fibulin-4(-/-) mice die just before birth due to arterial hemorrhage, but fibulin-4(+/-) mice appear to be outwardly normal. Experiments were therefore performed to determine whether fibulin-4(+/-) mice display arterial pathologies on a microscopic scale. After preliminary experiments were performed, a second purpose developed, which was to test the hypothesis that any observed pathologies would be ameliorated by housing the animals in enriched cages.

METHODOLOGY

Fibulin-4(+/-) and wild-type mice were housed either four/cage in standard cages or two per cage in larger cages, each cage containing a tunnel and a wheel. After three weeks the mice were sacrificed, and the aortas perfusion-fixed and excised for light and electron microscopy.

PRINCIPLE FINDINGS

When the mice were in standard cages, localized regions of disorganized extracellular matrix and collagen fibers consistently appeared between some of the medial smooth muscle cells in the fibulin-4(+/-) mice. In the wild-type mice, the smooth muscle cells were closely connected to each other and the media was more compact. The number of disorganized regions per square mm was significantly greater for fibulin-4(+/-) mice (172+/-43 (SEM)) than for wild-type mice (15+/-8) (p<0.01, n = 8). When the mice were in enriched cages, the fibulin-4(+/-) mice showed significantly fewer disorganized regions than those in standard cages (35+/-12) (p<0.05, n = 8). The wild type mice also showed fewer disorganized regions (3+/-2), but this difference was not significant.

CONCLUSIONS

These results indicate that arterial pathologies manifested in fibulin-4(+/-) mice can be reduced by enriching the housing conditions, and imply that appropriate environments may counteract the effects of some genetic deficiencies.

Effect of noise on microvascular integrity in laboratory rats

Housing rats in an environment with high personnel activity increases microvascular leakiness to albumin in the mesenteric microcirculation and causes mast cell degranulation. In this study, rats were exposed to daily 15-min episodes of 90-dB SPL noise to determine whether similar effects occurred and whether vitamin E with a-lipoic acid or Traumeel (a homeopathic anti-inflammatory-analgesic) reduced these effects. Groups of rats fed a control diet (1000 IU/kg vitamin E) only, the control diet with Traumeel, or a diet with 10,000 IU/kg vitamin E and 1.65 g/kg lipoic acid were exposed to daily noise for 3 to 5 wk; a fourth group of rats, fed control diet, was housed with no excess noise. The rats were anesthetized, the superior mesenteric artery cannulated, and a portion of the microvasculature perfused for 1 min with fluoroscein isothiocyanate-albumin before fixing for microscopy. All groups exposed to excess noise had significantly more leaks per venule length and greater leak area per venule length than did the quiet group. However, the number and area of leaks in the rats that received Traumeel or vitamin E were significantly smaller than those in rats exposed to noise only. In addition, mast cell degranulation was significantly lower in rats given Traumeel. Thus exposure of rats to excessive noise produces structural damage in the mesenteric microvasculature that is significantly reduced by dietary supplements.

Are investigators aware of environmental noise in animal facilities and that this noise may affect experimental data?

Control of environmental factors, such as noise, in animal facilities is important to ensure that research animals respond consistently to experimental procedures and that experimental results are not confounded by outside influences. A survey of personnel involved with animal facilities (173 respondents) showed that almost all agreed with this statement. However, 48% thought that one or more environmental factors in their facilities could be stressing the animals, and a majority of respondents reported generation of audible noise from people (72% of respondents), fans (61%), and squeaky carts (56%). The presence of these noises was correlated with the perception of noise as a problem because of its psychologic and physiologic effects on the animals. The amount of time respondents spent in the facilities was strongly correlated with their perception of noise as a problem, with veterinarians spending the most time and perceiving the most problems, and professors and assistant/ associate professors spending the least and perceiving the fewest. Therefore, they may lack key knowledge that can affect their research goals. In addition, because faculty are the least aware of noise as a potential problem but are primarily responsible for designing experiments, research involving animals may be confounded by noise as an unknown variable. This effect may lead to unnecessary numbers of animals being required to achieve statistical significance and possibly to erroneous interpretation of results. On the basis of the findings of this survey, we present recommendations for improving the environment, particularly for decreasing the noise level, in animal facilities.

Do audible and ultrasonic sounds of intensities common in animal facilities affect the autonomic nervous system of rodents?

In animal facilities, noises, often poorly controlled, occur over a wide range of frequencies and intensities. Evidence demonstrates that audible noise and ultrasound have deleterious effects on rodent physiology, but it is not known how they affect the autonomic nervous system (ANS). This study exposed 3 unrestrained, male, Sprague-Dawley rats daily to a 15-min white noise regime (90 dB), a quiet regime, or a 15-min ultrasound regime (90 dB at 4 frequencies in the range 20 to 40 kHz)--each for several weeks--and used radiotelemetry to monitor their cardiovascular responses. Exposure to audible noise increased heart rate and mean arterial pressure. Spectral analysis of HR variability showed diminished stimulation of the parasympathetic nervous system, shifting the sympathovagal balance. However, ultrasound, at the frequencies used, did not reproducibly affect cardiovascular parameters. The preliminary data obtained from this study indicate that audible noise, but not ultrasound (delivered using the same protocol), affects the ANS. Because the cardiovascular, respiratory, renal, and gastrointestinal systems are under autonomic control, such noise could have wide-ranging effects on animal physiology.

Effects of S-nitrosation on hemoglobin-induced microvascular damage

Blood substitutes, such as diaspirin cross-linked hemoglobin (Hb), cause microvascular leakiness to macromolecules. Because of the potentially stabilizing effects of nitric acid (NO) on endothelium, experiments were performed to determine whether S-nitrosohemoglobin (SNO-Hb), a potential NO-donor Hb-based blood substitute, would not cause microvascular damage. Release of NO, or its metabolites, from the SNO-Hb was facilitated by addition of glutathione, which aids in the decomposition of S-nitrosothiols. In anesthetized rats, the mesenteric microvasculature was perfused with SNO-Hb with glutathione (six rats), SNO-Hb alone (six rats), or saline (eight rats) for 10 min, followed by fluorescein isothiocyanate (FITC)-albumin for 1 min, and finally fixed for epifluorescence microscopic examination. When comparing the SNO-Hb group with saline, both the numbers and areas of leaks were significantly increased [0.019 +/- 0.003 (SEM) microm vs. 0.0030 +/- 0.0004 and 7.36 +/- 1.50 vs. 0.156 +/- 0.035 (p < 0.005)]. With the addition of glutathione, leakage was still high (0.005 +/- 0.00005 microm and 5.086 +/- 0.064 microm) but decreased compared with SNO-Hb alone (p < 0.005). In conclusion, NO, or a related vasodilator, when released from SNO-Hb, significantly reduces but does not eliminate microvascular damage. Further improvements may result by S-nitrosating a more stable form of modified hemoglobin.

Effect of noise on the morphology of the intestinal mucosa in laboratory rats

To determine whether noise-induced stress disrupts the intestinal mucosa of laboratory rats, one group of 8 rats ("noise" rats) was subjected to 15 min of white noise (90 dB) daily for 3 wk. Another group ("quiet"rats) was housed for 3 wk in an acoustically similar room but with no additional noise. A 3rd group ("recovery" rats) was housed in the noise room for 3 wk and then in the quiet room for a further 3 wk. The ilea were fixed for microscopy. Villi adjacent to Peyer patches showed significantly more degranulated mast cells (mean+/-standard error of the mean, 3.95+/-0.80 versus 0.35+/-0.29, respectively) and eosinophils (mean+/-standard error of the mean, 9.46+/-0.44 versus 4.58+/-0.38) per villus section in noise rats than in quiet rats. Similar results were obtained with rooms reversed, to account for any differences in room characteristics. The mean width of villus laminar propria was significantly greater in noise rats than quiet rats, suggesting edema. In addition, mucosal epithelial cells of noise rats were often separated, sometimes detaching from the basement membrane, whereas those of quiet rats were intact. Behaviorally, noise rats exhibited significantly more grooming and rearing than quiet rats. Compared with noise rats, recovery rats showed no reduction in mast cell degranulation or mean width of villus lamina propria, but there were increased numbers of secreting goblet cells in villi adjacent to Peyer patches and some recovery of epithelial integrity.

Personal Interaction with a Reiki Practitioner Decreases Noise-Induced Microvascular Damage in an Animal Model

OBJECTIVE

To determine whether Reiki, a process of transmission of healing energy, can significantly reduce microvascular leakage caused by exposure to excessive noise using an animal model.

RATIONALE

Reiki is beginning to be used in hospitals to accelerate recovery. Despite many anecdotes describing Reiki's success, few scientific studies are reported and none of those use animals. Animal models have the advantage over human subjects in that they provide well-controlled, easily interpretable experiments. The use of noise is relevant to hospital patients because of the excessive ambient noise in hospitals in the United Kingdom and United States. Loud noise can lead to several nonauditory disorders in humans and animals that impair recovery. In the rat, stress from noise damages the mesenteric microvasculature, leading to leakage of plasma into the surrounding tissue.

DESIGN

One group of four rats simultaneously received daily noise and Reiki, while two other groups received "sham" Reiki or noise alone. A fourth group did not receive noise or additional treatment. The experiment was performed three times to test for reproducibility.

OUTCOME MEASURES

Average number and area of microvascular leaks to fluorescent albumin per unit length of venule.

RESULTS

In all three experiments, Reiki significantly reduced the outcome measures compared to the other noise groups (sham Reiki and noise alone) (p < 0.01).

CONCLUSIONS

Application of Reiki significantly reduces noise-induced microvascular leakage in an animal model. Whether or not these effects are caused by Reiki itself, or the relaxing effect of the Reiki practitioner, this procedure could be useful for minimizing effects of environmental stress on research animals and hospital patients.

Mast cell activation by stress

Mental or emotional stress has been shown to cause mast cell degranulation in several different tissues. Several lines of experimental evidence indicate that stress, working through the sympathetic nervous system, or the hypothalamus-pituitary-adrenal axis, stimulates peripheral nerves to release neuropeptides that bind to receptors on the mast cells, causing them to degranulate. In order to investigate the effects of stress on mast cell degranulation, it is necessary to first establish a reproducible animal model of stress (in this case, rat) and also to ensure that the control animals do not show any signs of stress. This procedure requires a great deal of care and attention because the methods used by many institutions to house laboratory rodents, do in fact cause them stress. This topic is addressed in this chapter. In addition, two histological techniques are described to visualize connective tissue and mucosal mast cells and to assess their degree of degranulation.

Effects of phosphorothioate oligodeoxynucleotide on hemoglobin-induced damage to intestinal mucosa

Some "blood substitutes," such as human diaspirin cross-linked hemoglobin DBBF-Hb, can damage the intestinal mucosa. This response may be due to release of free iron from Hb leading to production of reactive oxygen species (ROS). Phosphorothioate oligodeoxynucleotides can bind and sequester iron. Therefore experiments were performed to test whether PS-ODN, composed of ten consecutive cytidines "C-10," reduces Hb-induced ROS generation and damage in the mucosa. Anesthetized Sprague-Dawley rats (4-6 per group) were injected arterially with 1 mg C-10, followed two minutes later by 50 mg DBBF-Hb. The positive controls received only DBBF-Hb and the negative controls either saline or PS-ODN followed by saline. Either ROS formation was monitored using a fluorescence technique, or the intestine was fixed for microscopy after 8 or 30 min. Sixty villi per rat were assigned an epithelial integrity index (EI), ranging from 1 (intact) to 3 (some cell-cell and cell-basement membrane separation). Pretreatment with PS-ODN significantly exacerbated DBBF-Hb-induced ROS formation, and PS-ODN groups showed significantly more epithelial damage near Peyer's patches, (EI of 1.93 +/- 0.06 (SEM) at 8 minutes and 1.31 +/- 0.04 at thirty minutes), than the negative controls, (1.11 +/- 0.02 at both 8 and 30 minutes), or the positive controls (1.43 +/- 0.05 at 8 minutes and 1.20 +/- 0.03 at 30 minutes) (p < 0.05). However, mast cell degranulation, eosinophil accumulation and goblet cell secretion were significantly reduced in the DBBF-Hb groups pre-treated with PS-ODN. Thus, PS-ODN, although an iron chelator, can significantly enhance epithelial damage caused by DBBF-Hb in the rat intestinal mucosa near Peyer's patches, possibly by formation of the ferryl component of the hemoglobin.

Effects of pulsation frequency and endothelial integrity on enhanced arterial transmural filtration produced by pulsatile pressure

The role of the endothelium in regulating transmural fluid filtration into the artery wall under pulsatile pressure and the effects of changes in pulsatile frequency on filtration have received little attention. Previous experiments (Alberding JP, Baldwin AL, Barton JK, and Wiley E. Am J Physiol Heart Circ Physiol 286: H1827-H1835, 2004) demonstrated significantly increased filtration after initial onset of pulsatile pressure compared with that predicted by using parameters measured under steady pressure. To determine the role of the endothelium in this phenomenon, the following experiments were performed on five New Zealand White rabbits (anesthetized with 30 mg/kg pentobarbital sodium). One of each pair of carotid arteries was deendothelialized, and filtration measurements under steady and pulsatile pressure were compared with those made in intact vessels (Alberding JP, Baldwin AL, Barton JK, and Wiley E. Am J Physiol Heart Circ Physiol 286: H1827-H1835, 2004). To determine the effect of increasing pulsatile frequency on arterial filtration, transmural filtration was measured by using pulsatile pressure frequencies of 1 Hz, followed by 2 Hz, in another set of intact arteries (6 arteries and 3 animals). For deendothelialized vessels, the initial increase in filtration after onset of pulsatility was similar to that observed in intact vessels, but the subsequent reduction in filtration was less abrupt. When pulsatile frequency was increased from 1 to 2 Hz in intact arteries, an initial increase in filtration was observed, similar to that obtained after onset of pulsatile pressure subsequent to a steady pressure. The observed responses of arteries to pulsatile pressure, with and without endothelium, or undergoing a frequency change, suggest a dynamic role for the endothelium in regulating transvascular transport in vivo.

Blood substitutes and redox responses in the microcirculation

Transfusion of hemoglobin-based blood substitutes, designed for their plasma expansion and oxygen transport capabilities, has resulted in some major problems, such as organ dysfunction, during clinical trials. Experimental evidence demonstrates that these hemoglobins damage tissue by producing highly reactive oxygen species. Although cell-free hemoglobin may present a low risk to people with normal redox status, patients who are sick and have a poor antioxidant status may be at risk. Oxidative damage is particularly dangerous in the microcirculation because excess leakage of plasma components into the interstitium will disturb the fluid balance between blood and tissue and alter the kinetics of delivery of intravascularly injected drugs, and endogenous enzymes and hormones, to various tissues. In this review, the redox chemistry of hemoglobin-based blood substitutes is briefly described, and their effects on cultured endothelial cells, and on the exchange properties of the microvasculature, are discussed. Taking into account the possible mechanisms by which oxidative damage can occur, various methods to reduce the deleterious effects of blood substitutes in vivo are evaluated. Finally, several possible cell signaling pathways that are triggered in endothelial cells, in response to modified hemoglobins, are considered in terms of protecting microvascular function.

Onset of pulsatile pressure causes transiently increased filtration through artery wall

Convective fluid motion through artery walls aids in the transvascular transport of macromolecules. Although many measurements of convective filtration have been reported, they were all obtained under constant transmural pressure. However, arterial pressure in vivo is pulsatile. Therefore, experiments were designed to compare filtration under steady and pulsatile pressure conditions. Rabbit carotid arteries were cannulated and excised from male New Zealand White rabbits anesthetized with pentobarbitol sodium (30 mg/kg iv administered). Hydraulic conductance was measured in cannulated excised rabbit carotid arteries at steady pressure. Next, pulsatile pressure trains were applied within the same vessels, and, simultaneously, arterial distension was monitored using Optical coherence tomography (OCT). For each pulse train, the volume of fluid lost through filtration was measured (subtracting volume change due to residual distension) and compared with that predicted from steady pressure measurements. At 60- and 80-mmHg baseline pressures, the experimental filtration volumes were significantly increased compared with those predicted for steady pressure ( P < 0.05). OCT demonstrated that the excess fluid volume loss was significantly greater than the volume that would be lost through residual distension ( P < 0.05). After 30 s, the magnitude of the excess of fluid loss was reduced. These results suggest that sudden onset of pulsatile pressure may cause changes in arterial interstitial hydration.

Differential effects of sodium selenite in reducing tissue damage caused by three hemoglobin-based oxygen carriers

Three “blood substitutes,” a diaspirin cross-linked human hemoglobin (DBBF-Hb), a bovine polymerized hemoglobin (PolyHbBv), and a human polymerized hemoglobin ( O-R-PolyHbA0), that have undergone clinical trials are used in this study. Previously, we showed in the rat that coadministration of sodium selenite (Na2SeO3) and DBBF-Hb significantly decreased mesenteric venular leakage and epithelial disruption produced by DBBF-Hb alone but did not reduce mast cell degranulation unless given orally. The purpose of this study was to determine whether Na2SeO3 produced similar beneficial responses when used with PolyHbBv and O-R-PolyHbA0. In anesthetized Sprague-Dawley rats, the mesenteric microvasculature was perfused with PolyHbBv or O-R-PolyHbA0, with and without Na2SeO3 in the perfusate and suffusate, for 10 min, followed by FITC-albumin for 3 min, and then fixed for microscopy. Na2SeO3 did not reduce leak number or area in preparations perfused with PolyHbBv and only reduced leak number (but not significantly) in preparations perfused with O-R-PolyHbA0. Na2SeO3 significantly increased mesenteric mast cell degranulation and impaired epithelial integrity in animals treated with PolyHbBv. In vitro, Na2SeO3 significantly reduced the oxidation rate of DBBF-Hb in the presence of oxidants, had little effect on PolyHbBv, and increased the oxidation rate of O-R-PolyHbA0. These results suggest that Na2SeO3 moderates hemoglobin-induced damage, at least partly, through its redox interactions with the heme sites in the hemoglobin molecules studied and that accessibility of the heme site to Na2SeO3 governs those interactions.

Disodium cromoglycate stabilizes mast cell degranulation while reducing the number of hemoglobin-induced microvascular leaks in rat mesentery

Blood substitutes, such as diaspirin cross-linked Hb (DBBF-Hb), have been considered for use during blood transfusions. Unfortunately, bolus injection of modified Hb has been shown to rapidly increase the leakage of microvessels to plasma albumin. This effect may result from production of excess reactive oxygen species (ROS) and could be linked to the observed increase in degranulated mast cells (DMC). Disodium cromoglycate (cromolyn) stabilizes mast cells and therefore might minimize the venular permeability in the rat mesentery. In 10 anesthetized Sprague-Dawley rats, the mesenteric preparation was continuously suffused with cromolyn while the microvasculature was filled with DBBF-Hb solution (10 mg/ml) for 10 min. Six animals received cromolyn pretreatment [two intravascular injections over 30 min (experiment A)] and four animals received pretreatment with 2% HEPES-buffered saline (HBS)-BSA (experiment B). Two more animals were pretreated with HBS-BSA without DBBF-Hb infusion but with cromolyn suffusion (experiment C). Another set of experiments was performed on five animals without cromolyn suffusion or any pretreatment but with DBBF-Hb infusion (experiment D). All groups then received a 1-min perfusion of FITC-albumin, fixation for 60 min, and microscopic examination. Experiments A and B demonstrated a significant reduction in the number of venular leaks and DMC compared with experiment D, but not in the area of venular leaks. These results suggest mast cell degranulation is not a major contributor to microvascular leakage induced by DBBF-Hb.

Role of the Actin Cytoskeleton in Regulating Endothelial Permeability in Venules

OBJECTIVE

This study was performed to determine the effect of myosin light chain kinase (MLCK) inhibition on histamine- and thrombin-induced venular permeability in the rat mesentery, coincidental with actin cytoskeleton changes.

METHODS

The mesenteric microvasculature of rats was perfused with a fluorescent tracer plus thrombin, histamine, or buffered saline, and the preparation was suffused with the MLCK inhibitor ML-7. The microvasculature then was stained for actin.

RESULTS

The average (+/- SE) number of leaks per micrometer of venule length of the thrombin plus 5 microM ML-7 treatment (35.3 +/- 5.9 x 10(-4); n = 224) was significantly lower than that for the thrombin-only treatment (61.7 +/- 5.6 x 10(-4); n = 385; p < 0.001). The histamine preparations required higher concentrations of ML-7 to significantly reduce the number of leaks. A concentration of 100 microM reduced the average leak number from 20.8 +/- 3.9 x 10(-4) (n = 140) to 2.5 +/- 0.8 x 10(-4) (n = 383; p < 0.001), but 20 microM ML-7 had no effect. Although leaky areas of both the thrombin- and histamine-treated preparations showed disruptions of the peripheral actin rim coincident with fluorescein isothiocyanate-bovine serum albumin leaks, qualitative and quantitative differences were identified.

CONCLUSIONS

The results suggest both similar and dissimilar mechanisms for thrombin and histamine regarding in situ endothelial gap formation.

Are laboratory animals stressed by their housing environment and are investigators aware that this stress can affect physiological data?

Although stress can affect the behavior and physiology of laboratory animals, there has been little investigation into how the quality of animal research is affected if the animals are stressed. Even minor perturbations (i.e., environmental noise) can produce a stress response. A pilot survey was designed (29/49 responded) to determine the prevalence of noise in animal facilities and whether researchers are aware that noise can affect animal physiology. Most respondents agreed that environmental factors are stressful to laboratory animals (97%) and minor pain/stress causes physiological changes (62%). Of 19/29 respondents who believed their facility was quiet, 8 identified at least 3-5 pronounced noise sources. We hypothesize that the level of extraneous noise considered acceptable by an investigator depends on their degree of awareness that environment can affect an animal's physiology, and their perception of the existence of 'mind-body' interactions in an animal.

Sodium selenite reduces hemoglobin-induced venular leakage in the rat mesentery

Modified Hbs are being developed as "blood substitutes," but intravascular injection of diaspirin cross-linked Hb (DBBF-Hb) can produce venular leakage. Hb toxicity may arise from reactive oxygen species, so the antioxidant sodium selenite (Na(2)SeO(3)) was used in an attempt to reduce leak formation. In anesthetized Sprague-Dawley rats, one-half of which received 2 x 10(-6) g/ml Na(2)SeO(3) in their drinking water for 3 wk, the mesenteric microvasculature was perfused with 2 mg/ml DBBF-Hb (N = 8) for 10 min. Controls (N = 7) received saline. This was followed by perfusion with FITC-albumin for 3 min, fixation, and microscopic examination. In rats given DBBF-Hb, Na(2)SeO(3) significantly reduced leak number, leak area, and mast cell degranulation. Venular leakage was also reduced in rats that only received Na(2)SeO(3) locally during DBBF-Hb perfusion. However, Na(2)SeO(3) did not affect animals receiving cyanomet-DBBF-Hb instead of DBBF-Hb and significantly increased leak number and mast cell degranulation in animals receiving saline. In vitro, Na(2)SeO(3) reduced the oxidation rate of DBBF-Hb while in the presence of oxidants. These results suggest that Na(2)SeO(3) reduces DBBF-Hb-induced microvascular leakage partly by retarding the oxidation of its heme iron.

Comparison of effects of two hemoglobin-based O(2) carriers on intestinal integrity and microvascular leakage

Two "blood substitutes," a diaspirin cross-linked human hemoglobin [bis(3,5 dibromosalicyl)fumarate, DBBF-Hb] and a bovine polymerized hemoglobin (PolyHbBv), advanced to clinical trials, are used in this study. Previously, we have shown that injection of DBBF-Hb into the rat circulation produces venular leakage and intestinal epithelial disruption. The purpose of this study was to determine whether PolyHbBv, currently approved for veterinary use in the United States, shows similar effects. In anesthetized Sprague-Dawley rats, the mesenteric microvasculature was perfused with DBBF-Hb (n = 6), PolyHbBv (n = 5), cyanomet Hb (CNmet-DBBF-Hb), or HEPES-buffered saline with 0.5% bovine serum albumin (HBS-BSA) (controls, n = 7) for 10 min, followed by FITC-albumin for 3 min, and then fixed for microscopy. For DBBF-Hb, the mean leak number per micrometer venule length [2.41 +/- 0.33 (+/-SE) x 10(-3)] was significantly greater than for PolyHbBv (0.53 +/- 0.14 x 10(-3)), CNmet-DBBF-Hb (0.36 +/- 0.14 x 10(-3)), and HBS-BSA (0.12 +/- 0.08 x 10(-3)) (P < 0.01). Corresponding quantities for leak area were 0.10 +/- 0.03, 0.010 +/- 0.003, 0.005 +/- 0.003, and 0.02 +/- 0.02 microm(2)/microm. In rats injected with DBBF-Hb (n = 8), intestinal epithelial integrity was significantly compromised compared with those injected with PolyHbBv (n = 5) or saline (n = 6). These results indicate that intravascular PolyHbBv produces significantly less disruption of the intestinal exchange barrier than does DBBF-Hb, probably because the heme is not so easily oxidized.

Mechanics of endothelial cell architecture and vascular permeability

Blood vessel walls form a selective barrier to the transport of materials between blood and tissue, and the endothelium contributes significantly to this barrier function. The role of the endothelium is particularly important in thin-walled vessels, such as venules, because during tissue inflammation the endothelial junctions widen in localized areas and gaps form, thus compromising the barrier function. The mechanisms of endothelial gap formation are still under question. In this review we describe what is known about the structure of endothelial cell-cell junctions and how this structure can change during inflammation. We then consider two possible mechanisms by which endothelial gaps are formed: active endothelial cell contraction or breakdown of the junctional complex, followed by passive recoil. Using measured values of the mechanical properties of endothelial cells, and the forces to which they are subjected, we calculate that gap formation by breakdown of cellular adhesion, followed by passive recoil, is a feasible mechanism. Finally, since endothelial cell surfaces, including junctions, are coated with a glycocalyx, we consider the question of whether changes in the glycocalyx can markedly increase endothelial permeability. We conclude that gap formation can occur by active contraction or by breakdown of adhesion, depending on the inflammatory mediator, and that the responses of the glycocalyx may also play an important role in the regulation of microvascular permeability.

Selenium reduces hemoglobin-induced epithelial damage to intestinal mucosa

Modified hemoglobins are being considered as possible "blood substitutes." Experiments were performed to determine whether diaspirin cross-linked hemoglobin (DBBF-Hb) produces epithelial damage and whether this is reduced by selenium (Se). Anesthetized Sprague-Dawley rats, half of which received 2 x 10(-6) g/ml Se, daily for 3 weeks, in their drinking water, were injected with a 5 ml bolus of 10 mg/ml DBBF-Hb. Control animals received saline (5 animals per group). After 30 minutes, the intestine was perfusion-fixed for light and electron microscopy. Eighty villi per rat were assigned an epithelial integrity index (E.I.), ranging from 1 (intact) to 3 (some cell-cell and cell-basement membrane separation). In non-Se rats, E.I. was significantly compromised by DBBF-Hb, compared to HBS-BSA (2.47+/-0.57 (SD) vs. 1.36+/-0.49, p<0.001). In Se rats, neither injection with DBBF-Hb or HBS-BSA caused epithelial damage (1.03+/-0.17 vs. 1.07+/-0.26). Mast cell degranulation per villus (MCD) was measured in 60 villi per rat. In non-Se rats, MCD was significantly greater after DBBF-Hb than after HBS-BSA injection (1.83+/-1.42 vs. 0.2+/-0.4). Supplementary Se did not reduce this effect. In fact, MCD was significantly increased in both sets of rats compared to their non-Se counterparts (3.27+/-2.40 and 1.48+/-1.70 for DBBF-Hb and HBS-BSA, respectively). Since mast cell mediators damage cells, Se must protect the mucosal epithelium in some way.

Introduction: a brief history of capillaries and some examples of their apparently strange behaviour

1. Over the past decade, evidence has accumulated challenging the notion that the smallest blood vessels, the capillaries, are static, uniform, semipermeable pipes with no function except as a passive barrier marking the boundary between the vascular compartments from the tissue compartment. 2. Instead, capillaries are dynamic structures that participate in the active regulation of water, waste and nutrient exchange, the formation and destruction of exchange vessels and the sites for initiation of signals to regulate the flow of blood into the exchange vascular network. 3. The following papers will provide insight into the expanded appreciation of the varied nature of capillaries and how their functions are co-ordinated to achieve 'whole organ' exchange.

Nitric oxide protects venules against histamine-induced leaks

OBJECTIVE

The goal of the present study was to investigate the prophylactic role of nitric oxide (NO) in the mesenteric microvasculature in preventing microvascular leakage subsequent to histamine application, and to evaluate the response of mast cells during these conditions.

METHODS

Regions of the rat mesenteric microcirculation were flushed free of blood and pretreated with either the nitric oxide donor sodium nitroprusside (SSP 10(-6) M) or Hepes-buffered saline containing 0.5% bovine serum albumin (HBS-BSA) for 15 minutes, then exposed to histamine (10(-3) M) for another three minutes. In another set of experiments, the microvasculature was treated with either histamine (10(-3) M) for three minutes or SNP (10(-6) M) for 15 minutes. A control group was treated with HBS-BSA for 15 minutes.

RESULTS

The protective role of NO was evaluated by its ability to reduce or prevent histamine-induced venular leaks. Mesenteric microvessels pretreated with SNP before histamine suffusion showed a significant decrease in both area and number of venular leaks following the perfusion of fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA). Although SNP pretreatment did not reduce the percentage of mast cells that degranulated in the presence of histamine, it did somewhat reduce the severity of the degranulation.

CONCLUSION

This study demonstrated that nitric oxide availability protects mesenteric venules against histamine-induced leaks, but does not prevent degranulation of mast cells. Therefore, nitric oxide probably acts directly on venular endothelial cells to prevent leak formation.

Structural alterations in the rat kidney after acute arsine exposure

The mechanism of arsine (AsH3) toxicity is not completely understood. In this investigation, the toxicity of AsH3 and AsH3-produced hemolytic products was determined in primary culture of renal cortical epithelial cells and in the in situ isolated rat kidney. The objective of this study was to model kidney dysfunction caused by AsH3 exposure. The hypothesis was that unchanged AsH3 and AsH3-produced hemolysate that may contain arsenite (As(III)) as metabolite are both responsible for renal toxicity. Toxicity in isolated cells was determined by 2, 3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxa nilide inner salt (XTT) bioreduction, intracellular potassium (K+), and lactate dehydrogenase (LDH) leakage. Data from XTT bioreduction showed that most toxicity occurred at 1 hour and was independent of the arsenic species. At 4 hours, the observed toxicity depended on the arsenic species and was generated by As(III). In the isolated cells, the As(III)-spiked hemolysate produced similar toxicities with regard to intracellular K and LDH. The AsH3-hemolysate only affected LDH at 1 hour. Unchanged AsH3 was very toxic to the isolated rat kidney. In this system, after 10 minutes exposure to AsH3, the effects of toxicity were observed mainly in the glomerular and peritubular endothelial cells. Tubular epithelial cells also presented early signs of toxicity. The AsH3-hemolysate was not toxic after a 1 -minute exposure. These data suggested that early cytotoxicity caused by unchanged AsH3 results in kidney dysfunction, produced by AsH3, and later by the formation of a hemolysate that may contain As(III). These data may be important in understanding the renal toxic effects after AsH3 intoxication.

Financial and risk considerations for successful disease management programs

Results for disease management [DM] programs have not been as positive as hoped because of clinical issues, lack of access to capital, and administrative issues. The financial experience of DM programs can be quite volatile. Financial projections that are protocol-based, rather than experience-based, may understate the revenue required and the range of possible costs for a DM program by understating the impact of complicating conditions and comorbidities. Actuarial tools (risk analysis and risk projection models) support better understanding of DM contracts. In particular, these models can provide the ability to quantify the impact of the factors that drive costs of a contract and the volatility of those costs. This analysis can assist DM companies in setting appropriate revenue and capital targets. Similar analysis by health plans can identify diseases that are good candidates for DM programs and can provide the basis for performance targets.

Nitric oxide: role in venular permeability recovery after histamine challenge

Histamine is an inflammatory mediator produced by mast cells that reside close to blood vessels. It causes a transient increase in venular permeability and stimulates endothelial production of nitric oxide (NO). In this study, we investigated the role that NO plays in the permeability recovery and evaluated the response of mast cells. The mesenteric microvasculature of anesthetized rats was suffused with 10(-3) M histamine for 3 min and then perfused with the NO donor sodium nitroprusside (SNP; 10(-6) M), the NO inhibitor N(G)-monomethyl-L-arginine (L-NMMA; 10(-5) M), its enantiomer (D-NMMA; 10(-5) M), or HEPES-buffered saline containing 0.5% BSA for 15 min. This was replaced by FITC-albumin for 3 min, followed by fixative. The vasculature was visualized using epifluorescence microscopy and was stained for mast cells. Preparations treated with histamine only showed discrete FITC-albumin leaks. Subsequent inhibition of NO increased venular FITC-albumin leaks and prevented permeability recovery, whereas subsequent treatment with SNP decreased the histamine-induced venular leaks. Mast cells degranulated due to histamine and the other treatment combinations. In conclusion, inhibition of NO prevented permeability recovery and depleted mast cells of their histamine content.

Environmental stress causes mast cell degranulation, endothelial and epithelial changes, and edema in the rat intestinal mucosa

OBJECTIVE

Mental stress has been shown to produce intestinal disease, but the effects of a mild environmental stress on intestinal physiology have not been elucidated. This study was performed to determine the effects of environmental stress on the ultrastructure of the intestinal mucosa, using the rat as an experimental model.

METHODS

One group of rats (group A, n = 3) was examined immediately upon arrival at the animal care facility. Groups B (n = 6) and C (n = 6) were housed in rooms with high and low personnel activity, respectively, for up to 4 wk. Group D (n = 8) was housed in the high activity room for 3 to 4 wk followed by 1, 2, or 3 in the low activity room.

RESULTS

Rats in group B had the greatest number of degranulated intestinal mucosal mast cells, and activated goblet cells. Intestinal villi were edematous and epithelial cells were detaching from the basement membrane at villus tips. Changes were observed in capillary endothelial ultrastructure. In group B there were greater numbers of vesicles and multilamellar fenestral diaphragms compared to group C. Rats in groups A and C had the lowest numbers of degranulated mast cells and activated goblet cells. Intestinal villi showed normal ultrastructure. Group D was in a recovery phase and the condition of the intestinal mucosa was improved relative to group B, but the number of degranulated mast cells was not significantly reduced.

CONCLUSIONS

This study demonstrates that environmentally induced stress causes pathological changes in the rat intestinal mucosa that compromise the epithelial-endothelial exchange barrier. These results emphasize the importance of closely monitoring the environment of experimental animals and provide evidence to stimulate further research into the mechanisms linking mental stress to gastrointestinal dysfunction in humans.

Environmental stress causes mast cell degranulation, endothelial and epithelial changes, and edema in the rat intestinal mucosa

OBJECTIVE

Mental stress has been shown to produce intestinal disease, but the effects of a mild environmental stress on intestinal physiology have not been elucidated. This study was performed to determine the effects of environmental stress on the ultrastructure of the intestinal mucosa, using the rat as an experimental model.

METHODS

One group of rats (group A, n = 3) was examined immediately upon arrival at the animal care facility. Groups B (n = 6) and C (n = 6) were housed in rooms with high and low personnel activity, respectively, for up to 4 wk. Group D (n = 8) was housed in the high activity room for 3 to 4 wk followed by 1, 2, or 3 in the low activity room.

RESULTS

Rats in group B had the greatest number of degranulated intestinal mucosal mast cells, and activated goblet cells. Intestinal villi were edematous and epithelial cells were detaching from the basement membrane at villus tips. Changes were observed in capillary endothelial ultrastructure. In group B there were greater numbers of vesicles and multilamellar fenestral diaphragms compared to group C. Rats in groups A and C had the lowest numbers of degranulated mast cells and activated goblet cells. Intestinal villi showed normal ultrastructure. Group D was in a recovery phase and the condition of the intestinal mucosa was improved relative to group B, but the number of degranulated mast cells was not significantly reduced.

CONCLUSIONS

This study demonstrates that environmentally induced stress causes pathological changes in the rat intestinal mucosa that compromise the epithelial-endothelial exchange barrier. These results emphasize the importance of closely monitoring the environment of experimental animals and provide evidence to stimulate further research into the mechanisms linking mental stress to gastrointestinal dysfunction in humans.

Effect of early transient adherent leukocytes on venular permeability and endothelial actin cytoskeleton

In a time course study of the development and recovery of venular leaks, it was shown that, after as early as 3 min of histamine application, venular leak formation was identified [Baldwin, A. L., and G. Thurston. Am. J. Physiol. 269 (Heart Circ. Physiol. 38): H1528-H1537, 1995]. This was accompanied by changes in the endothelial actin cytoskeleton and the presence of adherent leukocytes. The venular leaks remained elevated for at least 30 min, whereas the adherent leukocytes were decreased by 20 min. The present study was performed to determine the role that 3 min (early), transient histamine-associated adherent leukocytes play in the formation of venular leaks and changes in the endothelial actin cytoskeleton. In anesthetized rats, the microvasculature of a mesenteric window was perfused with buffered saline or fucoidin. FITC-BSA or FITC-BSA and 10(-4) M histamine was added to the perfusate for the last 3 min. The vasculature was perfusion fixed, stained for filamentous actin, and viewed microscopically. Fucoidin pretreatment significantly reduced the number of early, transient histamine-associated adherent leukocytes (P < 0.01). The number of adherent leukocytes in leaky venules was significantly greater than that seen in nonleaky venules (P < 0.01); however, the reduction in the number of histamine-associated adherent leukocytes with fucoidin pretreatment had no significant effect on the number (P > 0.05) or area (P > 0.05) of FITC-BSA leaks or on the endothelial actin cytoskeleton.

Modified hemoglobins produce venular interendothelial gaps and albumin leakage in the rat mesentery

Cross-linked hemoglobin (alphaalpha-Hb) and polyethylene glycol (PEG)-conjugated Hb have both been considered as possible "blood substitutes." Previously, we showed that PEG-Hb extravasates rapidly in the intestinal mucosa and causes transient epithelial sloughing, resulting in temporary opening of the intestinal epithelial barrier. In the present study, the rat mesenteric preparation was used to quantify the effects of the two Hbs on microvascular leakage to albumin and to investigate possible changes in the integrity of the interendothelial cell junctions and the endothelial actin cytoskeleton. In anesthetized Sprague-Dawley rats, the microvasculature of a mesenteric window was perfused with HEPES-buffered saline (HBS) containing 0.5 mg/ml BSA and 2 mg/ml alphaalpha-Hb (n = 16) or PEG-Hb (n = 5) for 2 or 10 min. Controls (n = 4) just received HBS-BSA. In some experiments (n = 9 for alphaalpha-Hb; n = 5 for PEG-Hb), the perfusate was then replaced by FITC-albumin in HBS-BSA for the next 3 min. The vasculature was then perfusion fixed, stained for filamentous actin and for mast cells, and viewed microscopically. In the remaining experiments, the mesenteric microvasculature was stained with silver nitrate to determine the number of endothelial junctional gaps per length of venules. Both Hbs increased the number and area of leaks per micrometer of venular length compared with control, but alphaalpha-Hb increased to a greater extent than PEG-Hb. Formation of leaks was accompanied by changes in the endothelial actin cytoskeleton and by an increased number of endothelial gaps. Mast cell degranulation was significantly greater (P < 0.05) in Hb-treated preparations compared with controls, but there was no direct correlation between sites of degranulation and albumin leakage. These Hbs appear to induce venular leakage in the mesentery by mechanisms similar to those previously observed after treatment with histamine or nitric oxide synthase inhibitors.

Cadherin-5 redistribution at sites of TNF-alpha and IFN-gamma-induced permeability in mesenteric venules

The response of the endothelial permeability barrier in microvascular networks of the rat mesentery to perfused immune inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) was examined. TNF-alpha (12.5 U/ml) treatment did not change albumin permeability, but in combination with IFN-gamma (20 U/ml), there was a marked increase in the number of sites of extravascular albumin in postcapillary venules. Endothelial integrity was characterized by cadherin-5 immunoreactivity, which was localized to the continuous intercellular junctions of endothelium in arterioles, capillaries, and venules. Perfusion with the combined cytokines showed that the increased albumin permeability was dose dependent and correlated with the focal disorganization of cadherin-5 at intercellular junctions of venular endothelium. No correlation was found between the increase in albumin permeability and the localization of intravascular leukocytes or extravascular mast cells. These results show that the combination of TNF-alpha and IFN-gamma induces an endothelial phenotype with focal loss of cadherin-5 intercellular adhesion, which, in part, facilitates passage of blood macromolecules and cells to the interstitium.

Effects of environmental stress on the architecture and permeability of the rat mesenteric microvasculature

OBJECTIVE

This study was performed to determine the effects of environmental stress on the leakage to albumin and architecture of microvessels in the rat mesentery.

METHODS

One group of rats (Group A, n = 6) were examined immediately upon arrival at the animal care facility. Groups B (n = 24) and C (n = 32) were housed in rooms with high and low personnel activity, respectively, for up to 7 weeks. Group D (n = 18) was housed in the high activity room for 2, 3, or 4 weeks followed by the low activity room.

RESULTS

Rats in the low activity room for 3-4 weeks showed robust microvascular networks within 25% to 50% of the mesenteric windows (each window consisting of the tissue extending between two adjacent feeding arterioles in the mesentery), whereas rats in Group B only showed fragile vessels at the edges of the mesenteric windows within fat deposits. Groups A and C demonstrated little mesenteric fat and few fragile vessels, in contrast to group B. Group D showed increased mesenteric networks and decreased mesenteric fat as recovery progressed. The microvascular networks of 6 rats, randomly selected from Group C, showed few venular leaks following perfusion with fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA). Such leaks were abundant in the mesenteric microvasculature of 3 rats randomly selected from Group B.

CONCLUSIONS

This study demonstrates that environmentally induced stress alters the architecture and leakage to albumin of the rat mesenteric microvasculature, and emphasizes the importance of closely monitoring the environment of experimental animals.

Ultrastructural effects of intravascularly injected polyethylene glycol-hemoglobin in intestinal mucosa

Polyethylene glycol (PEG)-conjugated Hb (PEG-Hb) is being considered as a blood substitute. Previously, we showed that PEG-Hb extravasates rapidly from the intestinal mucosa and causes transient epithelial sloughing, resulting in temporary unimpeded passage of material between the intestinal lumen and the microcirculation. The present study quantifies the time course of factors related to this disturbance. Anesthetized Sprague-Dawley rats (350-450 g) were injected with a bolus of PEG-Hb (10 mg/ml) in saline. Control animals received saline, alone or with Dextran 70 (5 mg/ml). After 2, 8, 15, 60, or 90 min, the small intestine was perfusion fixed for microscopy (4 animals for each time point). Epithelial cell detachment and mucosal mast cell degranulation peaked at 2 and 8-15 min, respectively, but by 90 min were back to normal. Goblet cell secretion increased with time up to 8-15 min, after which it leveled off. Mean interstitial width was significantly greater 8 min after injection than for controls and continued to increase with time. In capillaries, endothelial fenestral diaphragms were replaced by thick, amorphous structures. Mesenteric mast cell degranulation was significantly greater 60-90 min after injection compared with controls. We propose that these results are consistent with intravascular injection of PEG-Hb invoking a transient inflammatory response in the intestine.

Inhibition of nitric oxide synthesis increases venular permeability and alters endothelial actin cytoskeleton

Inhibition of nitric oxide (NO) synthesis using NG-nitro-L-arginine methyl ester (L-NAME) or NG-monomethyl-L-arginine (L-NMMA) increases venular permeability in the rat mesentery (I. Kurose, R. Wolf, M. B. Grisham, T. Y. Aw, R. D. Specian, and D. N. Granger. Circ. Res. 76: 30-39, 1995), but the cellular mechanisms of this response are not known. This study was performed to determine whether such venular leaks are associated with changes in the endothelial actin cytoskeleton. In anesthetized Sprague-Dawley rats, the microvasculature of a mesenteric window was perfused with buffered saline, with or without 10(-5) M L-NAME, L-NMMA, or the inactive enantiomer NG-nitro-D-arginine methyl ester for 3 or 30 min. FITC-albumin was added to the perfusate for the last 3 min. The vasculature was perfusion fixed, stained for filamentous actin and for mast cells, and viewed microscopically. In control preparations, venules showed few FITC-albumin leaks and the endothelial actin cytoskeleton consisted of a peripheral rim along the cell-cell junctions. Preparations treated with L-NAME or L-NMMA showed significantly more leakage, the actin rims in leaky venules were discontinuous, and short, randomly oriented fibers appeared within the cells. In nonleaky venules, the peripheral actin rims sometimes contained small, equally spaced discontinuities not seen in control preparations. Although a mast cell stabilizer was used, 27-70% of the mast cells were degranulated in the presence of L-NMMA. Thus inhibition of NO synthesis alters the endothelial cytoskeleton and increases albumin leakage from mesenteric venules, either directly or indirectly via the involvement of mast cells.

Identification and determination of material properties for porohyperelastic analysis of large arteries

A "porohyperelastic" (PHE) material model is described and the theoretical framework presented that allows identification of the necessary material properties functions for soft arterial tissues. A generalized Fung form is proposed for the PHE constitutive law in which the two fundamental Lagrangian material properties are the effective strain energy density function, W(e), and the hydraulic permeability, kij. The PHE model is based on isotropic forms using W(e) = Ue (phi) = 1/2C0(e phi - 1) and the radial component of permeability, kRR = kRR(phi), with phi = C1'(I1 - 3) + C2'(I2 - 3) + K'(J - 1)2. The methods for determination of these material properties are illustrated using experimental data from in situ rabbit aortas. Three experiments are described to determine parameters in Ue and kRR for the intima and media of the aortas, i.e., (1) undrained tests to determine C0, C1', and C2'; (2) drained tests to determine K'; and (3) steady-state pressurization tests of intact and de-endothelialized vessels to determine intimal and medial permeability (adventitia removed in these models). Data-reduction procedures are presented that allow determination of kRR for the intima and media and Ue for the media using experimental data. The effectiveness and accuracy of these procedures are studied using input "data" from finite element models generated with the ABAQUS program. The isotropic theory and data-reduction methods give good approximations for the PHE properties of in situ aortas. These methods can be extended to include arterial tissue remodeling and anisotropic behavior when appropriate experimental data are available.

Acute blood stasis reduces interstitial uptake of albumin from intestinal microcirculatory networks

Temporary blood flow stoppage occurs in a greater percentage of the capillaries when blood flow to organs is reduced. Previous studies on the small intestine have suggested that acute blood stasis (< or = 10 min) results in expression of negative charge, not present when blood flow is brisk, on the luminal surface of mucosal capillaries. Negative surface charge would tend to reduce transcapillary passage of albumin from blood to interstitium, since albumin is also negatively charged. Here we test the hypothesis that acute blood stasis reduces the interstitial uptake of albumin from mucosal capillary networks in rat small intestine in situ. Animals were subjected to two treatments, which included intestinal blood flow and acute stasis. After each treatment, fluorescent albumins were perfused into the intestinal circulation, and then interstitial fluorescence was recorded using fluorescence microscopy. Images were later quantified by computer analysis. After brisk blood flow, but not after acute blood stasis, fluorescence rapidly appeared in the interstitium and resulted in higher interstitial fluorescence intensity values. These results may have relevance to the mechanisms by which albumin flux in the small intestine is synchronized with digestion and fasting, which are associated with high and low intestinal blood flow, respectively.

Effect of atherosclerosis on transmural convection an arterial ultrastructure. Implications for local intravascular drug delivery

Local infusion of agents through perforated catheters may reduce neointimal formation following vascular angioplasty. Such treatment will succeed only if the drug is retained within the arterial intima long enough to promote repair. Drugs will be dispersed throughout the wall predominantly by transmural convection instead of diffusion if the Peclet number, Pe = J (1-delta f)/P, is greater than unity, where J is the transmural fluid flow per unit surface area and delta(f) and P are the reflection and permeability coefficients to the drug, respectively. Although the targets of local drug delivery will be atherosclerotic vessels, little is known about the transport properties of these vessels. Accordingly, we evaluated the effects of hypercholesterolemia and atherosclerosis on J per unit pressure (hydraulic conductance, Lp) and on ultrastructure in femoral arteries. Measurements were made at 30, 60, and 90 mm Hg in anesthetized New Zealand white rabbits fed a normal diet (n = 6) and after 3 weeks of lipid feeding (n = 19). Atherosclerosis was induced in six lipid-fed animals by air desiccation of a femoral artery. Hydraulic conductance was significantly greater in vessels from hypercholesterolemic than from normal animals and decreased with pressure only in hypercholesterolemic arteries. Atherosclerosis did not augment hydraulic conductance compared with hypercholesterolemia alone. Electron microscopic examination demonstrated damaged endothelium in hypercholesterolemic arteries and both altered endothelium and less tightly packed medial tissue, compared with controls, in atherosclerotic vessels, at least at lower pressures. Peclet numbers for macromolecules exceeded unity for all three groups of arteries and reached 0.3 to 0.4 for molecules as small as heparin. Thus, convection plays a dominant role in the distribution of macromolecular agents following local delivery and may result in their rapid transport to the adventitia in the femoral artery.

Changes in endothelial actin cytoskeleton at leakage sites in the rat mesenteric microvasculature

Pages H316–H329: Gavin Thurston, Ann L. Baldwin, and Lisa M. Wilson. “Changes in endothelial actin cytoskeleton at leakage sites in the rat mesenteric microvasculature.” The volume number in the abstract line was incorrectly cited and should appear as the following.

Thurston, Gavin, Ann L. Baldwin, and Lisa M. Wilson.Changes in endothelial actin cytoskeleton at leakage sites in the rat mesenteric microvasculature. Am. J. Physiol. 268 ( Heart Circ. Physiol. 37): H316–H329, 1995.