Multicomponent telerehabilitation programme for older veterans with multimorbidity: a programme evaluation.

INTRODUCTION: Older veterans with multimorbidity experience physical, mental and social factors which may negatively impact health and healthcare access. Physical function, behaviour change skills and loneliness may not be addressed during traditional physical rehabilitation. Thus, a multicomponent telerehabilitation programme could address these unmet needs. This programme evaluation assessed the safety, feasibility and change in patient outcomes for a multicomponent telerehabilitation programme. METHODS: Individuals were eligible if they were a veteran/spouse, age ≥50 years and had ≥3 comorbidities. The telerehabilitation programme included four core components: (1) High-intensity rehabilitation, (2) Coaching interventions, (3) Social support and (4) Technology. Physical therapists delivered the 12-week programme and collected patient outcomes at baseline, 4 weeks, 8 weeks and 12 weeks. Programme evaluation measures included safety events (occurrence and type), feasibility (adherence) and patient outcomes (physical function). Safety and feasibility outcomes were analysed using descriptive statistics. The mean pre-post programme difference and 95% CI for patient outcomes were generated using paired t-tests. RESULTS: Twenty-one participants enrolled in the telerehabilitation programme; most were male (81%), white (72%) and non-Hispanic (76%), with an average of 5.7 (3.0) comorbidities. Prevalence of insession safety events was 3.2% (0.03 events/session). Fifteen (71.4%) participants adhered to the programme (attended ≥80% of sessions). Mean (95% CI) improvements for physical function are as follows: 4.7 (2.4 to 7.0) repetitions for 30 s sit to stand, 6.0 (4.0 to 9.0) and 5.0 (2.0 to 9.0) repetitions for right arm curl and left arm curl, respectively, and 31.8 (15.9 to 47.7) repetitions for the 2 min step test. CONCLUSION: The telerehabilitation programme was safe, feasible and demonstrated preprogramme to postprogramme improvements in physical function measures while addressing unmet needs in a vulnerable population. These results support a randomised clinical trial while informing programme and process adaptations.

Reactive oxygen species mediate high glucose-induced heparanase-1 production and heparan sulphate proteoglycan degradation in human and rat endothelial cells: a potential role in the pathogenesis of atherosclerosis.

AIMS/HYPOTHESIS: The content of heparan sulphate is reduced in the endothelium under hyperglycaemic conditions and may contribute to the pathogenesis of atherosclerosis. Heparanase-1 (HPR1) specifically degrades heparan sulphate proteoglycans. We therefore sought to determine whether: (1) heparan sulphate reduction in endothelial cells is due to increased HPR1 production through increased reactive oxygen species (ROS) production; and (2) HPR1 production is increased in vivo in endothelial cells under hyperglycaemic and/or atherosclerotic conditions. METHODS: HPR1 mRNA and protein levels in endothelial cells were analysed by RT-PCR and Western blot or HPR1 enzymatic activity assay, respectively. Cell surface heparan sulphate levels were analysed by FACS. HPR1 in the artery from control rats and a rat model of diabetes, and from patients under hyperglycaemic and/or atherosclerotic conditions was immunohistochemically examined. RESULTS: High-glucose-induced HPR1 production and heparan sulphate degradation in three human endothelial cell lines, both of which were blocked by ROS scavengers, glutathione and N-acetylcysteine. Exogenous H(2)O(2) induced HPR1 production, subsequently leading to decreased cell surface heparan sulphate levels. HPR1 content was significantly increased in endothelial cells in the arterial walls of a rat model of diabetes. Clinical studies revealed that HPR1 production was increased in endothelial cells under hyperglycaemic conditions, and in endothelial cells and macrophages in atherosclerotic lesions. CONCLUSIONS/INTERPRETATION: Hyperglycaemia induces HPR1 production and heparan sulphate degradation in endothelial cells through ROS. HPR1 production is increased in endothelial cells from a rat model of diabetes, and in macrophages in the atherosclerotic lesions of diabetic and non-diabetic patients. Increased HPR1 production may contribute to the pathogenesis and progression of atherosclerosis.

Clinician and staff perspectives on potential disparities introduced by the rapid implementation of telehealth services during COVID-19: a mixed-methods analysis.

The COVID-19 pandemic has rapidly altered ambulatory health care delivery and may have worsened disparities in health care access. To assess the telehealth implementation experiences of ambulatory personnel in different disciplines and their perspectives on potential telehealth disparities, and to make recommendations for more equitable telehealth delivery. We used a convergent parallel mixed-methods design. Clinic managers from geriatric medicine, internal medicine, and psychiatry e-mailed a survey to clinicians and staff regarding experiences with telehealth care delivery. Quantitative survey responses were analyzed with Fisher's Exact tests. Qualitative responses were coded thematically. Recommendations were categorized by type of implementation strategy. Quantitative and qualitative findings on telehealth disparities were merged in a joint data display. Respondents (n = 147, 57% response rate) were distributed across three specialties: 66% internal medicine, 19% psychiatry, and 14% geriatric medicine. Prior to 2020, 77% of clinicians had never delivered telehealth services. By Spring 2020, 78% reported conducting more than half of clinic visits by telehealth. Among clinicians, 52% agreed/strongly agreed that rapid telehealth implementation exacerbated access to care disparities to: older adult patients, those with limited internet access, and those needing interpretation services. Staff expressed similar difficulties with telehealth set-up especially for these patients. To improve telehealth equity, clinicians recommended to: (i) change infrastructure; (ii) train and educate stakeholders; and (iii) support clinicians. Clinicians and staff reported specific subpopulations had challenges in accessing telehealth visits. To avoid perpetuating telehealth access disparities, further co-discovery of equitable implementation strategies with patients and clinics are urgently needed.

Thrombin receptor peptide inhibits thrombin-induced increase in endothelial permeability by receptor desensitization.

Thrombin, a potent activator of cellular responses, proteolytically cleaves, and thereby activates its receptor. In the present study, we compared the effects of the thrombin receptor 14-amino acid peptide (TRP-14; SFLLRNPNDKYEPF), which comprises the NH2 terminus after cleavage of the thrombin receptor, and of the native alpha-thrombin on endothelial monolayer permeability. Addition of TRP-14 (1-200 microM) to bovine pulmonary artery endothelial cells increased [Ca2+]i in a dose-dependent manner. The peak increase in [Ca2+]i in response to 100 microM TRP-14 or 0.1 microM alpha-thrombin was similar (i.e., 931 +/- 74 nM and 1032 +/- 80 nM, respectively), which was followed by a slow decrease with t1/2 values of 0.73 and 0.61 min, respectively. Extracellular Ca2+ chelation with 5 mM EGTA abolished the sustained increases in [Ca2+]i induced by either TRP-14 or alpha-thrombin. alpha-thrombin (0.1 microM) increased transendothelial [125I]albumin permeability, whereas TRP-14 (1-100 microM) had no effect. Coincubation of 100 microM TRP-14 with 1 microM DIP-alpha-thrombin also did not increase permeability over control values. Stimulation of BPAEC with 0.1 microM alpha-thrombin induced translocation of protein kinase C (PKC) from the cytosol to the plasma membrane indicative of PKC activation, whereas TRP-14 had no effect at any concentration. TRP-14 at 100 microM desensitized BPAEC to thrombin-induced increases in [Ca2+]i and transendothelial permeability. The Ca2+ desensitization was reversed after approximately 60 min, and this recovery paralleled the recovery of the permeability response. These findings indicate that the TRP-14-induced Ca2+ mobilization in the absence of PKC activation is insufficient to increase endothelial permeability. In contrast, the increase in endothelial permeability after alpha-thrombin occurred in conjunction with Ca2+ mobilization as well as PKC activation. TRP-14 pretreatment prevented the alpha-thrombin-induced increase in endothelial permeability secondary to desensitization of the Ca2+ signal. The results suggest that combined cytosolic Ca2+ mobilization mediated by TRP-14 and PKC activation mediated by a TRP-14-independent pathway are dual signals responsible for the thrombin-induced increase in vascular endothelial permeability.

The human HMGB1 promoter is modulated by a silencer and an enhancer-containing intron.

The highly conserved, ubiquitous high mobility group protein HMGB1 (formerly named as HMG1) is an architectural transcription factor encoded by a single functional gene in human. HMGB1 is expressed in almost all cell or tissue types studied. In general, it is expressed at a basal level in most cells but at a slightly elevated level of 2--3-fold in actively proliferating tissues or estrogen stimulated breast cancer cells. To understand the regulatory mechanism controlling expression of the human HMGB1 gene, we cloned and analyzed the upstream region as well as the first intron of this gene. We found that transcription of the human HMGB1 gene in the breast cancer MCF-7 cells starts at one major site 57 nucleotides upstream from the first exon-intron boundary. Expression of the human HMGB1 gene is under the control of a very strong TATA-less promoter, which has an activity more than 18-fold that of the SV40 promoter. Immediately upstream, a silencer element is present. This silencer can repress the activity of the HMGB1 promoter down to just one-sixth. The first intron of the human HMGB1 gene contains enhancer elements, which can increase the human HMGB1 promoter activity by 2--3-fold. We postulate that the human HMGB1 gene is capable of being expressed at a very high level. The basal level of expression observed in most cells is probably a result of the strong promoter being held in check by the silencer. The 2--3-fold increase in HMGB1 expression observed in proliferating cells or breast cancer cells stimulated by estrogen may probably result from the action of the enhancer elements in intron 1.

The chicken genome contains no HMG1 retropseudogenes but a functional HMG1 gene with long introns.

We have cloned the genomic sequence coding for the high mobility group 1 (HMG1) protein in chickens. Multiple sequence alignment shows that the chicken HMG1 gene is highly homologous to the human and the mouse HMG1 genes. The gene structure of chicken HMG1 is similar to that of the mouse and the human HMG1 genes, with the same exon-intron boundaries. However, in contrast to other avian genes that have shorter introns, the chicken HMG1 gene has introns that are twice as long as their mammalian homologues. In addition to the functional, intron-containing HMG1 gene, all mammalian genomes contain more than 50 copies of HMG1 retropseudogenes each, while in the chicken genome there are no HMG1 retropseudogenes. This finding suggests that the HMG1 retropseudogenes arose in mammals after their divergence away from the birds.

CD18 integrin-dependent endothelial injury: effects of opsonized zymosan and phorbol ester activation.

We examined the hypothesis that neutrophil (PMN)-mediated injury of the vascular endothelium is dependent on adhesion of PMNs to endothelial cells via the leukocyte adhesion glycoprotein CD11/CD18. We compared the PMN activation responses [i.e. adhesion to cultured endothelial cells, superoxide (O2-) production, degranulation, and cytosolic [Ca2+] ([Ca2+]i)] and endothelial injury elicited by opsonized zymosan (OZ, which is phagocytosed by PMNs) or phorbol 12-myristate 13-acetate (PMA, a protein kinase C activator). The basal adherence of nonstimulated PMNs to bovine pulmonary artery endothelial cells (BPAEC) was 9.0 +/- 1.1 PMN/field. PMA and OZ increased PMN adherence to BPAEC (to 31.1 +/- 1.4 and 39.8 +/- 3.8 PMN/field, respectively), which in both cases was inhibited by anti-CD18 monoclonal antibody (mAb) IB4. Stimulation of PMNs with PMA or OZ produced injury to 73% and 53% of BPAEC examined, respectively, which corresponded to 6.8-fold and 3.5-fold increases in transendothelial 125I-albumin permeability from baseline. Pretreatment of PMNs with mAb IB4 prevented endothelial injury in both cases. Both PMA and OZ increased the production of O2- (by 7.6-fold and 3.1-fold over control, respectively) and promoted the release of myeloperoxidase (5.2-fold and 9.1-fold over control, respectively) (P < .01). IB4 did not inhibit the PMA- or OZ-induced increases in O2-. IB4 did not inhibit the PMA-induced myeloperoxidase release but reduced by approximately 29% the OZ-induced myeloperoxidase release. Stimulation of PMNs layered on BPAEC with OZ (0.5 mg/ml) caused an approximately 7-fold increase in PMN [Ca2+]i over baseline, which decayed to a steady-state level above baseline at 10 min. IB4 (10 micrograms/ml) alone did not alter baseline [Ca2+]i and did not inhibit the OZ-induced increase in [Ca2+]i. In contrast to OZ, stimulation of PMNs with PMA did not increase [Ca2+]i. The results indicate that the protective effects of the anti-CD18 mAb IB4 were associated predominantly with its antiadherence property. Therefore, CD18 integrin-mediated PMN adhesion to the endothelium is a critical determinant of endothelial injury irrespective of the PMN-activating stimulus.

Update on pulmonary edema: the role and regulation of endothelial barrier function.

Discovery of the pathophysiologic mechanisms leading to pulmonary edema and identification of effective strategies for prevention remain significant clinical concerns. Endothelial barrier function is a key component for maintenance of the integrity of the vascular boundary in the lung, particularly since the gas exchange surface area of the alveolar-capillary membrane is large. This review is focused on new insights in the pulmonary endothelial response to injury and recovery, reversible activation by edemagenic agents, and the biochemical/structural basis for regulation of endothelial barrier function. This information is discussed in the context of fundamental concepts of lung fluid balance and pulmonary function.

Regulation of endothelial barrier function by the cAMP-dependent protein kinase.

Elevation of cAMP promotes the endothelial cell (EC) barrier and protects the lung from edema development. Thus, we tested the hypothesis that both increases and decreases in PKA modulate EC function and coordinate distribution of regulatory, adherence, and cytoskeletal proteins. Inhibition of PKA activity by RpcAMPS and activation by cholera toxin was verified by assay of kemptide phosphorylation in digitonin permeabilized EC. Inhibition of PKA by RpcAMPS or overexpression of the endogenous inhibitor, PKI, decreased monolayer electrical impedance and exacerbated the decreases produced by agonists (thrombin and PMA). RpcAMPS directly increased F-actin content and organization into stress fibers, increased co-staining of actin with both phosphatase 2B and myosin light chain kinase (MLCK), caused reorganization of focal adhesions, and decreased catenin at cell borders. These findings are similar to those evoked by thrombin. In contrast, cholera toxin prevented the agonist-induced resistance decrease and protein redistribution. Although PKA activation attenuated thrombin-induced myosin light chain (MLC) phosphorylation, PKA inhibition per se did not cause MLC phosphorylation or affect [Ca2+]i. These studies indicate that a decrease in PKA activity alone can produce disruption of barrier function via mechanisms not involving MLCK and support a central role for cAMP/PKA in regulation of cytoskeletal and adhesive protein function in EC which correlates with altered barrier function.

A species comparison of alveolar size and surface forces.

The independent roles of alveolar size and surface tension in relation to lung stability were investigated in 11 different mammalian species whose body weight ranged from 0.03 to 50 kg. This range in species provided a wide variation in subgross anatomy as well as a fourfold range in alveolar diameter. Alveolar diameter was estimated from the mean linear intercept (Lm) of fixed lungs. Quasi-static pressure-volume curves were determined in excised lungs and the percent volume remaining on deflation from total lung capacity at 30 cmH2O to 10 cmH2O (%V10) provided an index of deflation stability related to functional surfactant. Surface tension of lung extract was measured in the Wilhelmy balance, and the minimum surface tension measured provided an index of surface tension lowering capacity of surfactant. Relationships of %V10 with alveolar diameter and surface tension with alveolar diameter were examined for correlations. Our results indicated that despite a range in Lm between 31 and 133 micron (mouse to pig), %V10 did not change in proportion with Lm across species. Similarly, minimum surface tension was about the same (6.1 to 8.8 dyn/cm) across a threefold difference in alveolar diameter. These results suggest that a stable alveolar configuration is maintained by both surface and tissue forces in a complex manner yet to be analyzed.

Morphological evidence for alveolar recruitment during inflation at high transpulmonary pressure.

The effect of continuous inflation of lungs at 30 cmH2O transpulmonary pressure (Ptp) on air-space size was assessed by chord length-frequency distribution analysis. Lungs from gerbils were excised, allowed to collapse freely, and inflated to 30 cmH2O Ptp in a humidified chamber kept at 37 degrees C. When the lungs appeared fully inflated with no observable pleural surface atelectasis, the left lung was occluded while the right was maintained at 30 cmH2O for 10 min longer and then occluded. During this time, the right lung increased its volume from 70 to 100%. Then both lungs were quick frozen, freeze dried, and embedded in glycol methacrylate, and 1- to 2-microns-thick histological sections cut. Lungs from a control group of gerbils were similarly inflated to 30 cmH2O, both left and right were occluded, the left was quick frozen immediately, and the right was frozen 10 min later. Chord lengths of air spaces from cranial and caudal lobes of lungs were acquired using a Dapple Systems image analyzer, and a two-population frequency distribution was generated for analysis with an IBM PC. The results indicate that the volume increase during continuous inflation at 30 cmH2O Ptp was associated with a shift in the chord length distribution toward the smaller chord lengths. A two-population statistical analysis indicated that the inflation resulted in an increase in the relative proportion of smaller chord lengths, with no increase in the mean of this smaller population. We conclude that continuous inflation at 30 cmH2O Ptp results in alveolar recruitment.

Calcium dependence of the thrombin-induced increase in endothelial albumin permeability.

We examined whether the increase in endothelial albumin permeability induced by alpha-thrombin is dependent on extracellular Ca2+ influx. Permeability of 125I-albumin across confluent monolayers of cultured bovine pulmonary artery endothelial cells was measured before and after the addition of 0.1 microM alpha-thrombin. In the presence of normal extracellular Ca2+ concentration ([Ca2+]o, 1000 microM), alpha-thrombin produced a 175 +/- 10% increase in 125I-albumin permeability. At lower [Ca2+]o (100, 10, 1, or less than 1 microM), alpha-thrombin caused a 140% increase in permeability (P less than 0.005). LaCl3 (1 mM), which competes for Ca2+ entry, blunted 38% of the increase in permeability. Preloading endothelial monolayers with quin2 to buffer cytosolic Ca2+ (Cai2+) produced a dose-dependent inhibition of the increase in 125I-albumin permeability. Preincubation with nifedipine or verapamil was ineffective in reducing the thrombin-induced permeability increase. A 60 mM K+ isosmotic solution did not alter base-line endothelial permeability. alpha-Thrombin increased [Ca2+]i in a dose-dependent manner and the 45Ca2+ influx rate. Extracellular medium containing 60 mM K+ did not increase 45Ca2+ influx, and nifedipine did not block the rise in 45Ca2+ influx caused by alpha-thrombin. Ca2+ flux into endothelial cells induced by alpha-thrombin does not occur through voltage-sensitive channels but may involve receptor-operated channels. In conclusion, the increase in endothelial albumin permeability caused by alpha-thrombin is dependent on Ca2+ influx and intracellular Ca2+ mobilization.

Dark CO2-fixation and diurnal malic acid fluctuations in the submerged-aquatic Isoetes storkii.

In the leaves (but not corms) of the submerged aquatic Isoetes storkii malic acid concentration fluctuated from 22 µeg g FW-1 in the evening to 171 µeg g FW-1 in the morning. Associated with this was a change in titratable acidity of 152 µeg g FW-1 between morning and evening. 14C carbon was fixed in both the light and the dark, though the amount of carbon fixed in the light was more than that fixed in the dark. Autoradiographs show 88% of 14CO2 fixed in the dark is recovered after 1 h, in malic acid and the remainder in one other unidentified product, whereas these two products contain less than 15% of the 14C fixed after 1 h exposure to 14CO2 in the light. It is suggested that CAM metabolism in this aquatic species may be related to the low availability of CO2 for photosynthesis during the day in its aquatic environment and that this metabolic pathway may prove common in the genus Isoetes.

Modeling vehicle accidents and highway geometric design relationships.

The statistical properties of four regression models--two conventional linear regression models and two Poisson regression models--are investigated in terms of their ability to model vehicle accidents and highway geometric design relationships. Potential limitations of these models pertaining to their underlying distributional assumptions, estimation procedures, functional form of accident rate, and sensitivity to short road sections, are identified. Important issues, such as the treatment of vehicle exposure and traffic conditions, and data uncertainties due to sampling and nonsampling errors, are also discussed. Roadway and truck accident data from the Highway Safety Information System (HSIS), a highway safety data base administered by the Federal Highway Administration (FHWA), have been employed to illustrate the use and the limitations of these models. It is demonstrated that the conventional linear regression models lack the distributional property to describe adequately random, discrete, nonnegative, and typically sporadic vehicle accident events on the road. As a result, these models are not appropriate to make probabilistic statements about vehicle accidents, and the test statistics derived from these models are questionable. The Poisson regression models, on the other hand, possess most of the desirable statistical properties in developing the relationships. However, if the vehicle accident data are found to be significantly overdispersed relative to its mean, then using the Poisson regression models may overstate or understate the likelihood of vehicle accidents on the road. More general probability distributions may have to be considered.

6-Hydroxydopamine-induced alterations in blood-brain barrier permeability.

Vascular inflammation is well known for its ability to compromise the function of the blood--brain barrier (BBB). Whether inflammation on the parenchymal side of the barrier, such as that associated with Parkinson's-like dopamine (DA) neuron lesions, similarly disrupts BBB function, is unknown. We assessed BBB integrity by examining the leakage of FITC-labeled albumin or horseradish peroxidase from the vasculature into parenchyma in animals exposed to the DA neurotoxin 6-hydroxydopamine (6OHDA). Unilateral injections of 6OHDA into the striatum or the medial forebrain bundle produced increased leakage in the ipsilateral substantia nigra and striatum 10 and 34 days following 6OHDA. Microglia were markedly activated and DA neurons were reduced by the lesions. The areas of BBB leakage were associated with increased expression of P-glycoprotein and beta 3-integrin expression suggesting, respectively, a compensatory response to inflammation and possible angiogenesis. Behavioural studies revealed that domperidone, a DA antagonist that normally does not cross the BBB, attenuated apomorphine-induced stereotypic behaviour in animals with 6OHDA lesions. This suggests that drugs which normally have no effect in brain can enter following Parkinson-like lesions. These data suggest that the events associated with DA neuron loss compromise BBB function.

Effects of 10% formalin fixation on fixed lung volume and lung tissue shrinkage. A comparison of eleven laboratory species.

This species comparative study examined tissue shrinkage from a known physiologic lung volume through to the processed histologic section. Eleven mammalian species with body weights that spanned 3 orders of magnitude were studied. Air pressure-volume curves were determined to obtain total lung capacity (TLC) at 30 cmH2O. The lungs were then fixed by airway filling at 25 cmH2O pressure, and a displacement fixed lung volume was determined. Linear dimensions were systematically measured on fixed tissue blocks, embedded tissue blocks, and stained sections. Results indicated that the ratio of fixed lung volume to TLC ranged between 0.6 and 2.0. The corresponding ratios for linear dimensions ranged between 0.8 and 1.3 for all species. Histologic processing caused further shrinkage; the ratios of linear dimensions measured after and to those measured before processing ranged between 0.6 and 0.7. Thus, the degree of fixed lung volume achieved relative to TLC varies considerably more among species than does the histologic shrinkage caused by processing. We conclude that measurement of these changes in lung dimensions caused by fixation and histologic processing in the different species is essential, particularly in quantitative interspecies physiologic studies.

Mechanisms of increased endothelial permeability.

The increase in endothelial permeability in response to inflammatory mediators such as thrombin and histamine is accompanied by reversible cell rounding and interendothelial gap formation, suggesting that the predominant transport pathway is a diffusive one (i.e., via cellular junctions (paracellular transport)). However, vesicle-mediated transport (i.e., via albumin-binding protein gp60) may also contribute significantly to the overall increase in permeability. Regulation of paracellular transport in endothelial cells is associated with modulation of actin-based systems, which anchor the cell to its neighbor or extracellular matrix, thus maintaining endothelial integrity. At the cell-cell junctions, actin is linked indirectly to the plasma membrane by linking proteins (e.g., vinculin, catenins, alpha-actinin) to cadherins, which function in homophilic intercellular adhesion. At endothelial focal contacts, the transmembrane receptors (integrins) for matrix proteins are linked to actin via linking proteins (i.e., vinculin, talin, alpha-actinin). In response to inflammatory mediators, second messengers signal two regulatory pathways, which modulate the actin-based systems, and can thus lead to impairment of the endothelial barrier integrity. One critical signal may be based on protein kinase C isoenzyme specific phosphorylation of linking proteins at the cell-cell and cell-matrix junctions. The increased phosphorylation is associated with actin reorganization, cell rounding, and increased paracellular transport. Another important event is the activation of myosin light chain kinase (MLCK), which causes an actin-myosin-based contraction that may lead to centripetal retraction of endothelial cells. Current research is being conducted at identification of protein substrates of protein kinase C isoenzymes, the specific role of their phosphorylation in barrier function, and determination of the precise role of MLCK in modulation of endothelial barrier function. Since mechanisms by which the increased permeability is returned to normal may be regulated at multiple levels (e.g., receptor desensitization, protein kinase C mediated negative feedback pathways, activation of protein phosphatases), it is also important to determine these cellular "off-switch" mechanisms.

Regulation of vascular endothelial barrier function.

The increase in endothelial permeability in response to inflammatory mediators such as alpha-thrombin and histamine is accompanied by cell rounding and interendothelial gap formation, implicating that the predominant transport pathway is a diffusive one [i.e., via cellular junctions (paracellular transport)]. However, the possible contribution by vesicle-mediated transport (i.e., via albumin binding protein gp60) to the overall permeability increase needs investigation. Regulation of paracellular transport in endothelial cells is associated with modulation of actin-based systems which anchor the cell to its neighbor or extracellular matrix, thus maintaining endothelial integrity. At the cell-cell junctions, actin is linked indirectly to the plasma membrane by linking proteins (e.g., vinculin, catenins, alpha-actinin) to cadherins, which function in homophilic intercellular adhesion. Cadherins may also play a role in regulating the formation of tight junctions, which also may be associated with actin. At endothelial focal contacts, the transmembrane receptors (integrins) for matrix proteins are linked to actin via linking proteins (i.e., vinculin, talin, alpha-actinin). In response to inflammatory mediators, second messengers signal two regulatory pathways which modulate the actin-based systems, which may lead to impairment of the endothelial barrier integrity. One pathway is based on protein kinase C (PKC) isozyme-specific phosphorylation of linking proteins at the cell-cell and cell-matrix junctions. The increased phosphorylation is associated with actin reorganization, cell rounding, and increased paracellular transport. The other is the activation of myosin light-chain kinase, (MLCK), which causes an actin-myosin-based contraction that may lead to a centripetal retraction of endothelial cells. Current research is in the identification of protein substrates of PKC isozymes, the specific role of their phosphorylation in barrier function, and determining the precise role of MLCK in modulation of endothelial barrier function.

Oxidant stress and endothelial cell dysfunction.

Reactive oxygen species (ROS) are generated at sites of inflammation and injury, and at low levels, ROS can function as signaling molecules participating as signaling intermediates in regulation of fundamental cell activities such as cell growth and cell adaptation responses, whereas at higher concentrations, ROS can cause cellular injury and death. The vascular endothelium, which regulates the passage of macromolecules and circulating cells from blood to tissues, is a major target of oxidant stress, playing a critical role in the pathophysiology of several vascular diseases and disorders. Specifically, oxidant stress increases vascular endothelial permeability and promotes leukocyte adhesion, which are coupled with alterations in endothelial signal transduction and redox-regulated transcription factors such as activator protein-1 and nuclear factor-kappaB. This review discusses recent findings on the cellular and molecular mechanisms by which ROS signal events leading to impairment of endothelial barrier function and promotion of leukocyte adhesion. Particular emphasis is placed on the regulation of cell-cell and cell-surface adhesion molecules, the actin cytoskeleton, key protein kinases, and signal transduction events.

Non-predatory ingestive behaviors of the praying mantids Tenodera aridifolia sinensis (Sauss.) and Sphodromantis lineola (Burr.).

Praying mantids are thought to be so strictly predacious that, historically, carnivorousness has been used as a defining characteristics of the taxon Mantodea, and no data exist on other ingestive behaviors. We observed food- and water-deprived male and female Tenodera aridifolia sinensis (Sauss.) and Sphodromantis lineola (Burr.) in various situations and found that their ingestive behaviors are more variable than generally recognized. Both species regularly drink water in response to deprivation, the amount imbibed being correlated with the total (but not daily) percent of initial body weight lost. When presented with stimuli consisting of plastic beads of different reflective quality (shiny clear, opaque frosted, or matte black), lighted by a single direct light source, the shiny stimuli consistently elicited the most drinking-like behavior by the mantids. The preference was consistent, whether stimuli were presented together or singly. This suggests that visual cues can be used to identify water and are alone capable of maintaining drinking-like behavior. When S. lineola were presented with various stimuli, including diced apple and diced banana, in a five-way or a three-way choice test, mantids that chose a stimulus within the allotted time consistently ate the diced banana. When presented one of two stimuli differing only in odor (30 x 20 x 15 mm cloth bags filled with either plastic beads or banana), S. lineola did not attempt to eat the former, but 50% attempted to eat the bag of banana. Eating bouts were always preceded by antennae drumming in the direction of, or over the stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)