Effects of asphyxia on telencephalic microvessels of premature beagle pups

The authors identified alterations in the brain microvasculature of the premature Beagle pup that could be attributed to asphyxia and potentially associated with the etiology of intraventricular hemorrhage (IVH). Beagle pups were delivered by cesarean section six days before their predicted whelping date and exposed to an alternating protocol of asphyxial episodes known to produce IVH. Data from the telencephalic microvasculature at both the germinal matrix (an area susceptible to IVH) and the borderzone cerebral cortex (an area rarely involved in hemorrhage) were analyzed. The germinal matrix microvessels responded differently to asphyxia than the cortical vessels. The germinal matrix microvessels maintained junctional complexes and intraluminal microvilli, and increased in cross-sectional luminal area following asphyxia; however, total vessel cross-sectional area did not change. After the asphyxial insult, cortical microvessels no longer exhibited intraluminal microvilli and increased in both total cross-sectional area and luminal area. The number of junctional complexes in cross-sections of cortical vessels was significantly reduced due at least in part to the narrowing of the endothelial cell lateral borders. The data provide indirect evidence to substantiate vasodilation speculated to be due to an increased cerebral blood flow to telencephalic vessels (both the germinal matrix and cerebral cortex) following asphyxia. The data also suggest differential rates of maturation between germinal matrix and cortical microvessels.

Buffer zones promoting oligotrophication in golf course runoffs: fiddler crabs as estuarine health indicators

Nitrogen pollution above a threshold level induces a eutrophication process in coastal creek ecosystems and consequently impacts on the water quality. The remedy for this scenario is the introduction of methods to enhance oligotrophication by means of constructed wetlands and buffer zones. This paper discusses new data on nitrogen flux and population changes in the primary consumers in the Bradley Creek ecosystem, adjacent to the Duck Haven Golf Course in southeastern North Carolina. In 1998-99, over different seasons, density distribution of the field populations of the fiddler crab Uca minax, was monitored as an indicator of environmental health. A control site at Whiskey Creek, adjacent to the University Center for Marine Sciences, was monitored in the same period since this site is not influenced by any golf course nutrient flux. The results pointed out that threshold level for optimum population density in Spartina grandiflora salt marsh is 0.1 mg/L of nitrates. A dense crab population, adjacent to the golf course with a buffer zone, was indicative of restoration of the estuarine ecosystem. A model, involving the use of constructed wetlands for oligotrophication, is being prepared on the basis of studies conducted by the University of South Alabama for a stormwater wetland constructed adjacent to the university's golf course.

Treatment of a molasses based distillery effluent in a constructed wetland in central India

A field-scale 4-celled, horizontal subsurface constructed wetland (CW) was installed to evaluate removal efficiencies of wastewater constituents in an industrial distillery effluent. Total and dissolved solids, NH4-N, TKN, P and COD were measured. This CW design provides four serial cells with synthetic liners and a river gravel base. The first two unplanted cells provide preliminary treatment. Specific gravel depths and ensuing biofilm growth provides anaerobic treatment in Cell 1 and anaerobic treatment in Cell 2. Cell 3 was planted with Typha latifolia with an inserted layer of brick rubble (for phosphorus removal). Locally grown reed, Phragmites karka was planted in Cell 4. COD was reduced from 8420 mg/l 3000 from Cell 1 to the outlet of Cell 4. Likewise other parameters: total and dissolved solids, ammonium and total nitrogen, and total P, indicated declining trends at the 4-celled CW effluent. This study reveals how high strength distillery wastewater strongly impacts morphology, aeration anatomy in the chiseled plant tissues, reed growth; and composition of the biofilm in the specialized substratum. The reliability of a CW for organic and nutrients reduction, in association with a poorly performing conventional system is discussed. There is an immense potential for appropriately designed constructed wetlands to improve high strength wastewaters in India.

Nociceptin/orphanin FQ inhibits ischaemia-induced glutamate efflux from rat cerebrocortical slices

Nociceptin/orphanin FQ (NC), the endogenous ligand for the G-protein coupled nociceptin receptor (NCR), has a modulatory role in various physiological processes including neurotransmitter release. We have examined the effects of NC, the analogues NC(1-13)NH2 and [F/G]NC(1-13)NH2 and the competitive antagonist [Nphe1]NC(1-13)NH2 (Nphe1) on glutamate efflux during an acute simulated ischaemic challenge in rat cerebrocortical slices. The increase in glutamate efflux seen with ischaemia was inhibited by NC (EC50 250 nM). At micromolar concentrations, the analogues were found to have a similar effect on glutamate efflux compared to NC. In all cases, inhibition of glutamate efflux was abolished by Nphe1 (30 microM). These results suggest a neuroprotective action for NC.

Meal fatty acid uptake in adipose tissue: gender effects in nonobese humans

We tested for gender differences in dietary fatty acid metabolism in 12 nonobese men and 12 nonobese women using the meal fatty acid tracer/adipose tissue biopsy study design. In addition to determining body composition, measurements of regional adipose tissue lipoprotein lipase activity, blood flow, and fat cell size were performed to place the meal fatty acid kinetic studies in perspective. Twenty-four hours after ingesting the test meal, the concentration of meal fatty acids was greater (P < 0.05) in abdominal subcutaneous than in thigh adipose tissue in both men (0. 61 +/- 0.12 vs. 0.45 +/- 0.09 mg/g) and women (0.59 +/- 0.10 vs. 0. 43 +/- 0.05) but was not different between men and women. A greater percentage of dietary fat was stored in subcutaneous adipose tissue in women than in men (38 +/- 3 vs. 24 +/- 3%, respectively, P < 0. 05), and a greater portion of meal fatty acid disposal was unaccounted for in men. Significant gender differences in regional adipose tissue blood flow after meal ingestion were noted; the differences were in the direction that could support greater nutrient storage in lower body fat in women.

Meal fatty acid uptake in human adipose tissue: technical and experimental design issues

The adipose tissue uptake of dietary fat has been studied using fatty acid radiotracers incorporated into a meal, followed by adipose tissue biopsies. A number of experimental design issues, including the use of isotopic tracers to measure meal fatty acid oxidation and plasma appearance of tracer, as well as the heterogeneity of adipose tissue fatty acid uptake, have been addressed. We examined these questions in a study of 24 volunteers (12 men and 12 women) who consumed a meal containing [(3)H]triolein and [(14)C]triolein. Slight differences in the purity of [(3)H]triolein vs. [(14)C]triolein were found, which could affect the apparent adipose tissue uptake of meal fatty acids. The adipose tissue triglyceride specific activity from bilateral biopsy sites agreed well, implying that a unilateral biopsy is satisfactory for measuring tracer uptake. Meal fatty acid oxidation measured using [(3)H]triolein and [(14)C]triolein was well correlated (r = 0.79, P < 0.0001). The peak tracer appearance in plasma chylomicrons occurred 1 h after the ingestion of a second, unlabeled meal. Our findings have implications for the experimental design of future meal fatty acid tracer/adipose tissue biopsy studies.

On the regulation of ischaemia-induced glutamate efflux from rat cortex by GABA; in vitro studies with GABA, clomethiazole and pentobarbitone

Prisms of adult rat cortex were maintained in vitro in either aerobic conditions (control) or conditions simulating an acute ischaemic challenge (hypoxia with no added glucose). Endogenous glutamate efflux increased with time in ischaemic conditions, being 2.7 fold higher than control efflux at 45 min. Returning prisms to control solution after 20 min of simulated ischaemia resulted in glutamate efflux returning to near-control values. Endogenous GABA efflux in ischaemic conditions also increased, being 4.5 fold higher than control efflux at 45 min. Ischaemia-induced glutamate efflux was not accompanied by increased lactate dehydrogenase efflux and was unaltered by omitting calcium from the extra-cellular solution and adding EGTA (0.1 mM). Both GABA and the GABA-mimetic clomethiazole inhibited ischaemia-induced glutamate efflux, with IC(50) values of 26 and 24 microM respectively. The maximum inhibition by either drug was 60 - 70%. Bicuculline (10 microM) abolished the inhibitory effect of GABA (100 microM) but not clomethiazole (100 microM). Picrotoxin (100 microM) abolished the action of both GABA and clomethiazole. Pentobarbitone inhibited glutamate efflux at 100 - 300 microM (maximal inhibition: 39%). Bicuculline (10 microM) abolished this effect. These data suggest that ischaemia-induced glutamate efflux from rat cerebral cortex is calcium-independent and not due to cell damage up to 45 min. The inhibitory effect of GABA, clomethiazole and pentobarbitone on ischaemia-induced glutamate efflux appears to be mediated by GABA(A) receptors. The results suggest that clomethiazole, unlike pentobarbitone, is able to activate the GABAA receptor-linked chloride channel directly and not merely potentiate the effect of endogenous GABA.

The role of anticipation and fear of pain in the persistence of avoidance behavior in patients with chronic low back pain

STUDY DESIGN

A correlative design using stepwise regression analysis.

OBJECTIVE

To explore the variation in spinal isometric strength that can be accounted for by anticipation of pain, sensory perception of pain, functional disability belief, and the fear-avoidance belief in chronic low back pain patients.

SUMMARY OF THE BACKGROUND DATA

Several biobehavioral factors contribute to the persistence of pain behavior in chronic patients. Recent studies suggest a need to explore the relation between reduced physical performance and the sensory and cognitive perception of pain.

METHODS

Sixty-three patients with chronic low back pain 20 to 56 years of age participated in this study. Visual Analogs Scales, the Fear-Avoidance Belief questionnaire, and the Disability Belief questionnaire were used to measure the sensory and cognitive dimensions of pain. Spinal isometric strength was measured by the Medx lumbar extension machine.

RESULTS

Analysis of variance and the stepwise regression analysis demonstrated that anticipation of pain and the fear-avoidance belief about physical activity significantly predicted variation in the spinal isometric strength deficit P < 0. 001. True pain experienced during the testing and answers to the Disability Belief questionnaire were not related.

CONCLUSION

The results of this study strongly support the hypothesis that spinal physical capacity in chronicity is not explained solely by the sensory perception of pain. The anticipation of pain and the fear-avoidance belief about physical activities were the strongest predictors of the variation in physical performance.

Variability in physician opinion on limiting pediatric life support

OBJECTIVE

We conducted this study to investigate how physicians in a pediatric intensive care unit (ICU) currently make decisions to withdraw and withhold life support. Consultation with the patient's primary caregiver often precedes decisions about withdrawal and limitation of life support in chronically ill patients. In these scenarios, the patient's primary caregiver was the pediatric oncologist. To evaluate the influence of subspecialty training, we compared the attitudes of the pediatric intensivists and the oncologists using scenarios describing critically ill oncology patients.

DESIGN

Cross-sectional survey. Each physician was randomly assigned 4 of 8 potential case scenarios.

SETTING

A total of 29 American pediatric ICUs.

PARTICIPANTS

Pediatric intensive care and oncology attendings and fellows.

INTERVENTION

Systematic manipulation of patient characteristics in two hypothetical case scenarios describing 6-year-old female oncology patients presenting to the ICU after the institution of mechanical ventilator support for acute respiratory failure. Cases 1 through 4 described a patient who, before admission, had a 99% projected 1-year probability of survival from her underlying cancer and suffered from severe neurologic disabilities. Cases 5 through 8 described a patient who was neurologically normal before admission and had a <1% chance of surviving longer than 1 year because of her underlying cancer. Each physician was randomly assigned 2 cases from cases 1 through 4 and 2 cases from cases 5 through 8. Within each of these case scenarios, parental preferences (withdraw or advance support or look for guidance from the caregivers) and probability of survival (5% vs 40%) were manipulated. Before distribution, the survey instrument was pilot-tested and underwent a rigorous assessment for clinical sensibility.

PRIMARY OUTCOME MEASURES

Physicians ratings of the importance of 10 factors considered in the decision to withdraw life support, and their decisions about the appropriate level of care to provide. Respondents were offered five management options representing five levels of care: 1) discontinue inotropes and mechanical ventilation but continue comfort measures; 2) discontinue inotropes and other maintenance therapy but continue mechanical ventilation and comfort measures; 3) continue with current management but add no new therapeutic intervention; 4) continue with current management, add additional inotropes, change antibiotics and the like as needed, but do not start dialysis; and 5) continue with full aggressive management and plan for dialysis if necessary. Respondents also were asked whether they would obtain an ethics consultation.

RESULTS

A total of 270 physicians responded to our survey (165 of 198 potentially eligible pediatric intensivists and 105 of 178 pediatric oncologists for response rates of 83% and 59%, respectively). The respondents considered the probability of ICU survival and the wishes of the parents regarding the aggressiveness of care most important in the decision to limit life-support interventions. No clinically important differences were found when the responses of oncologists were compared with those of intensivists. In six of eight possible scenarios, the same level of intensity of care was chosen by less than half of all respondents. In three scenarios, >/=10% of respondents chose full aggressive management as the most appropriate level of care, whereas another >/=10% chose comfort measures only when viewing the same scenario. The most significant respondent factors affecting choices were professional status (attending vs fellow) and the self-rated importance of functional neurologic status. The majority of respondents (83%) believed that the intensive care and the oncology staff were usually in agreement at their institution about the level of intervention to recommend to the parents. (ABSTRACT TRUNCATED)

Variations on an Expectancy-Value Model of Motivation in Science

Relationships among motivational variables from goal theory and expectancy-value theory were investigated in this correlational study of high school students. Self-report surveys of motivation in science were collected during biology classes from 69 males and 80 females. Outcome measures were effort, persistence, and achievement. Gender differences were noted in the pattern of zero-order correlations. Internal motivation variables were related to achievement in males but not females. Regression analyses indicated that the motivation variables explained large proportions of variance in the outcomes. However, the contribution of individual variables differed by gender. Most notable was perceived ability, which contributed significantly to predicting outcome measures for females but not males. Findings suggest that interventions may need to focus on different motivational aspects depending on gender. Copyright 1999 Academic Press.

Detection system for reaction-rate analysis in a low-volume proteinase-inhibition assay

High-throughput screening of large combinatorial chemical libraries in biochemical assays will benefit from reduced reagent volume and increased speed of measurement. Standard assays typically are performed in 96-well microtiter plates having 200-microL well volumes and up to an hour of incubation time. In this paper, we demonstrate a technique for precise and rapid measurement of the progress of an enzymatic reaction and its inhibition with reduced volume and time (for this work, the assay was mixed at the 200-microL level and detected in 2-microL volumes with minutes of total assay time). Directly measuring the enzyme activity in the small volume format yields a precise value for the median inhibitory concentration (IC50) of an inhibitor compound. The model assay is the endoproteolytic cleavage of a small fluorogenic peptide by human neutrophil collagenase (MMP-8). The fluorogenic peptide was labeled at one end with a UV/blue fluorophore (N-methylanthranilyl) and at the other end with a quencher (dinitrophenol). To generate inhibition data, a hydroxamate peptide analog inhibitor of collagenase, actinonin, was included in the reaction. The experiments were performed using ultraviolet laser illumination (325 nm wavelength) and parallel fluorescence detection by a cooled, charge-coupled-device camera system to increase sensitivity and speed. The assay volume was reduced to 2 microL for data collection, and the total time for mixing, incubation, and measurement was less than 6 min. For comparison to a standard format, the same assay was performed in a 96-well microtiter plate in 200 microL using 30 min of incubation and measurement in a microtiter plate fluorimeter. Median inhibitory concentrations (IC50) for actinonin of 73 +/- 16 and 100 +/- 14 nM were obtained in the 2- and 200-microL assays, respectively. One concern with assay miniaturization and increases in throughput is a potential loss of precision and accuracy. Laser excitation and parallel detection of fluorescence is a promising approach for increased speed and reduced cost without loss of precision for proteinase inhibition assays.

Functional aspects of skeletal muscle contractile apparatus and sarcoplasmic reticulum after fatigue

This study examined the effects of fatigue on the functional aspects of the contractile apparatus and sarcoplasmic reticulum (SR). Frog semitendinosus muscles were stimulated to fatigue, and skinned fibers or a homogenate fraction was prepared from both fatigued and rested contralateral muscles. In fatigued fibers, maximal Ca2+-activated force of the contractile apparatus was unaltered, whereas maximal actomyosin-ATPase activity was depressed by 20%. The Ca2+ sensitivity of force was increased, whereas that of actomyosin-ATPase was not altered. Also, the rate constant for tension redevelopment was decreased at submaximal Ca2+ concentration. These latter findings suggest that fatigue slows the dissociation of force-generating myosin cross bridges. Ca2+ uptake and Ca2+-ATPase activity of the SR were depressed by 46 and 21%, respectively, in the fatigued muscles. Fatigue also reduced the rates of SR Ca2+ release evoked by AgNO3 and 4-chloro-m-cresol by 38 and 45%, respectively. During fatigue, the contractile apparatus and SR undergo intrinsic functional alterations. These changes likely result in altered force production and energy consumption by the intact muscle.

Interaction of secretory leukocyte protease inhibitor with heparin inhibits proteases involved in asthma

Protease inhibition by secretory leukocyte protease inhibitor (SLPI) is accelerated by the sulfated polysaccharides. The nature of the SLPI-polysaccharide interaction, explored with affinity chromatography, indicated that this interaction was sensitive to the charge and type of polysaccharide. Dextran and chondroitin had the lowest affinity for SLPI, followed by dermatan, heparan, and dextran sulfates. While heparin bound SLPI tightly, the highest affinity heparin chains unexpectedly contained a lower level of sulfation than more weakly interacting chains. Heparin oligosaccharides, prepared using heparin lyase I were SLPI-affinity fractionated. Surprisingly, undersulfated heparin oligosaccharides bound SLPI with the highest affinity, suggesting the importance of free hydroxyl groups for high affinity interaction. Isothermal titration calorimetry was used to determine the thermodynamics of SLPI interaction with a low molecular weight heparin, an undersulfated decasaccharide and a tetrasaccharide. The studies showed 12-14 saccharide units, corresponding to molecular weight of approximately 4,800, were required for a 1:1 (SLPI:heparin) binding stoichiometry. Furthermore, an undersulfated decasaccharide was able to bind SLPI tightly (Kd approximately 13 nM), resulting in its activation and the inhibition of neutrophil elastase and pancreatic chymotrypsin. The in vitro assessment of heparin and the decasaccharide and tetrasaccharide using stopped-flow kinetics suggested that heparin was the optimal choice to study SLPI-based in vivo protease inhibition. SLPI and heparin were co-administered by inhalation in therapy against antigen-induced airway hyperresponsiveness in a sheep bronchoprovocation model. Heparin, in combination with SLPI demonstrated in vivo efficacy reducing early and late phase bronchoconstriction. Heparin also increased the therapeutic activity of SLPI against antigen-induced airway hyperresponsiveness.

Persistent pulmonary hypertension of the neonate and asymmetric growth restriction

OBJECTIVE

To evaluate the possible associations between persistent pulmonary hypertension of the neonate, need for extra-corporeal membranous oxygenation, small for gestational age (SGA), and low ponderal index for gestational age in infants with persistent pulmonary hypertension of the neonate and in matched controls.

METHODS

Eighty-six infants with persistent pulmonary hypertension of the neonate delivered from 1991 to 1994 at our hospital were matched with 430 contemporaneous control singleton neonates. Birth weight and ponderal indices (100 x weight/length3) less than the tenth percentile for gestational age and gender were defined as SGA and low ponderal index, respectively. We assessed associations between these markers, the presence of persistent pulmonary hypertension of the neonate, and the need for extracorporeal membranous oxygenation.

RESULTS

Low ponderal index was associated with persistent pulmonary hypertension of the neonate (odds ratio [OR] 5.4), whereas SGA was not. Low ponderal index (OR 4.0) was an independent correlate of persistent pulmonary hypertension of the neonate after adjustment with logistic regression for 5-minute Apgar scores less than 7, umbilical arterial pH less than 7.10, and presence of meconium. Low ponderal index was associated with need for extracorporeal membranous oxygenation in neonates with persistent pulmonary hypertension (P < .001).

CONCLUSION

Fetal developmental events may significantly affect neonatal pulmonary status. Diminished neonatal nutritional status, as measured by low ponderal index for gestational age, is associated with increased risk of persistent pulmonary hypertension of the neonate and severity of the disease process.

Intraobserver and interobserver reliability of assessments of impairments and disabilities

BACKGROUND AND PURPOSE

The purpose of this study was to evaluate the interobserver and intraobserver reliability of assessments of impairments and disabilities.

SUBJECTS AND METHODS

One physical therapist's assessments were examined for intraobserver reliability. Judgments of two pairs of therapists were used to examine interobserver reliability. Reliability was assessed by Cohen's kappa.

RESULTS

Of the 42 impairments and disabilities assessed by the physical therapist in the intraobserver reliability study, kappa values could be calculated for 33 items. For 31 items (94%), kappa values ranged from .40 to .91, and 2 items (6%) had kappa values of less than .40. To determine interobserver reliability, 37 items were assessed in one practice. Kappa values could be calculated for 34 items, with 30 items (88%) having kappa values ranging from .41 to .80 and 4 items (12%) showing "poor" agreement. In the second practice, 47 items were assessed for interobserver reliability. Kappa values could be calculated for 40 items, with 11 items (27.5%) having kappa values ranging from .41 to .84. Poor agreement was shown for the remaining 29 items (72.5%).

CONCLUSION AND DISCUSSION

Assessments of impairments and disabilities are potentially reliable. The differences between practices of the interobserver reliability study can be explained by the fact that one of the therapists did not receive training in the use of the assessment form. More generalizable conclusions will require further study with more subjects and therapists.

Inhibition of colon carcinoma cell lung colony formation by a soluble form of E-selectin

During metastasis, tumor cells adhere to vascular endothelia. E-selectin is an adhesive protein expressed by cytokine-activated endothelium that can support adhesion of colon cancer cells through the recognition of specific carbohydrate ligands. Using a series of colon carcinoma cell lines that displayed E-selectin adhesiveness and an increased metastatic capacity in cytokine-treated mice, we examined possible inhibition of cytokine-dependent experimental lung metastasis by a soluble form of E-selectin, the recombinant fusion protein E-selectin-immunoglobulin. We found that E-selectin-immunoglobulin bound to the surfaces of HT-29 colon carcinoma cells and blocked the formation of cytokine-inducible experimental lung metastases; control L-selectin-immunoglobulin also bound to HT-29 cells but had no effect on tumor cell lung colonization. E-selectin-immunoglobulin was found to interfere with E-selectin-dependent adhesion of HT-29 cells to activated vascular endothelium and to block the retention of these cells in the lung, a process that implies tumor cell adhesive interactions with the host vasculature. Our results demonstrate that E-selectin-immunoglobulin inhibits adhesion and formation of lung metastases by colon carcinoma cells and suggest that impairment of tumor cell-endothelium adhesion might represent a therapeutic approach to the metastatic diffusion of tumors.

Ethics in the intensive care unit. Creating an ethical environment

This article discusses ethical issues that exist each and every day in interactions with patients, families, and fellow workers in the ICU, even in the absence of overt conflict or controversy. The creation of an ethical working environment in the ICU is a necessary precondition for dealing with the ethical issues raised by specific issues such as cardiopulmonary resuscitation, the limitation or withdrawal of life-sustaining treatment, the special care of children with disabilities, brain death, and organ procurement, and triage. The creation of an ethical working environment requires developing a collaborative relationship with patients, families, staff, and other health care professionals.

Literature and ethical medicine: five cases from common practice

This essay is composed of five stories written by practicing physicians about their patients. Each clinical story describes a challenging ethical condition-potential abuse of medical power, gravely ill and probably over-treated newborns, iatrogenic narcotic addiction, deceived dying people. Rather than singling out one ethical conflict to resolve or adjudicate, the authors attempt, through literary methods, to grasp the singular experiences of their patients and to act according to the deep structures of their patients' lives. Examining these five stories with simple literary tools-attention to narrative frames, time, plot, and desire-reveals the mechanisms through which acts of writing and reading contribute to clinical clarity and ethical actions.

Carbohydrate-protein interactions in vascular biology

Carbohydrate-protein interactions participate in a wide variety of biological and pathological events. In recent years, particular attention has been paid to the carbohydrate-protein interactions that occur in vascular biology. Sialylated oligosaccharides are ligands of a structurally diverse group of proteins that include the selectins and members of the immunoglobulin superfamily. Various glycosaminoglycans can be recognized by an overlapping set of proteins that include two of the selectins and CD44. Emerging knowledge of carbohydrate-protein interactions in human pathophysiology are discussed.