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PubMed2004

Control of pulmonary surfactant secretion in adult California sea lions.

Marine mammals have a spectacular suite of respiratory adaptations to deal with the extreme pressures associated with deep diving. In particular, maintaining a functional pulmonary surfactant system at depth is critical for marine mammals to ensure that inspiration is possible upon re-emergence. Pulmonary surfactant is secreted from alveolar type II (ATII) cells and is crucial for normal lung function. It is not known whether ATII cells have the ability to continue to secrete pulmonary surfactant under pressure, or how secretion is maintained and controlled. We show here that surfactant secretion in California sea lions (Zalophus californianus) was increased after high pressures (25 and 50 atm) of short duration (30 min), but was unaffected by high pressures of long duration (2 h). This is in contrast to a similar sized terrestrial mammal (sheep), where surfactant secretion was increased after high pressures of both long and short duration. Z. californianus and terrestrial mammals also show similar responses to stimulatory hormones and autonomic neurotransmitters. It therefore seems that an increase in the quantity of surfactant in seal lungs after diving is most likely caused by mechanostimulation induced by pressure and volume changes, and that seals are adapted to maintain constant levels of surfactant under long periods of high pressure.

Animals↗
PubMed2004

Ethiopian refugees in the UK: migration, adaptation and settlement experiences and their relevance to health.

OBJECTIVE: The study explores Ethiopian refugees' and asylum seekers' experiences of migration, adaptation and settlement in the UK and their health beliefs and practices. DESIGN: Data was collected using semi-structured depth interviews and a semi-structured questionnaire. The sample consisted of 106 Ethiopians resident in the UK. RESULTS: The majority of the participants fled Ethiopia due to political reasons. Whilst 65% of them had lived in the UK for over five years only 7% had full refugee status. Many of the participants faced difficulties with the immigration system, housing and social services and felt socially isolated. Many also had problems with gaining employment or employment appropriate to their qualifications, and 29% were unemployed. The majority of the participants believe that happiness is a prerequisite to healthiness and also an indication of healthiness. On the other hand the majority believed that sickness is caused by disease and mental illness is caused by both supernatural and psychosocial causes. Most of the participants sought the help of their GP in the first instance of illness although some had experienced difficulties accessing health services due to language problems and poor understanding of the primary healthcare system. The participants also believed that the stress of adaptation and settlement affected their mental health and led to depression. CONCLUSION: Migration, adaptation and settlement experiences impact on the health of refugees and are dependent on a number of barriers and enablers, both at a personal and societal level. These should be taken into account in the provision of health and social care services, in particular services should be provided in a culturally competent manner.

Acculturation↗
PubMed1992

Adaptations to high hydrostatic pressure.

The importance of adaptation to high pressure has long been implicit in the findings of studies in which 1 atm-adapted species were subjected to elevated pressures. Recent comparative studies have shown that pressure sensitivities of enzymes, structural proteins, and membrane-based systems differ markedly between shallow- and deep-living species. These studies allow operational definition of what constitutes high pressures for different biological structures and processes. These are the habitat (adaptation) pressures at which a given type of system first exhibits reduced perturbation by pressure. These threshold pressures vary among physiological systems, but are similar for a given system among different species. Dehydrogenase enzymes and adenylyl cyclases exhibit threshold perturbation pressures of only 50-100 atm; the Na(+)-K(+)-ATPase of teleost gills appears to have a pressure perturbation threshold near 200 atm, and a similar threshold was found for actin self-assembly. Even this limited sample of physiological processes indicates that the terms deep and high pressure begin to apply at depths of only 500 m or less--and processes yet to be examined in comparative analysis may yield even lower pressure thresholds. The differences in sensitivity to pressure of homologous systems in shallow- and deep-living organisms have implications at several levels of biological organization. The vertical distribution patterns of species in aquatic habitats may be established, in part, by interspecific differences in resistance to pressure. High pressures may restrict the depths to which shallow-living species can penetrate, and the obligately barophilic systems found in deep-living organisms may limit their upper distribution limits. The similarities noted among the adaptations of deep-sea species with different shallow-water ancestors reflect a high degree of convergent evolution in pressure adaptation. It will be interesting to learn if the similarities in pressure-resistance of function among diverse deep-sea species are the result of similar or identical changes at the molecular level, e.g. in protein sequence. Acclimation to pressure may be of widespread occurrence among species that undergo large changes in depth, e.g. during ontogeny. Pressure acclimation may require pressure-regulation of gene expression. Lastly, comparisons of species from the cold deep sea with those from hydrothermal vents have shown that adaptations to both temperature and pressure play critical roles in determining the distribution patterns of deep-living species.

Adaptation, Physiological↗
PubMed2006

Extreme spatial variability and unprecedented methylmercury concentrations within a constructed wetland.

We began monitoring concentrations of both total mercury (THg) and methylmercury (MeHg) in surface water at Stormwater Treatment Area-2 (STA) on July 20, 2000. This 2602 hectare STA was constructed with three independent marshes to remove phosphorus from agricultural runoff and reduce eutrophication in the northern Everglades. However, there was concern that in doing so, STA-2 might inadvertently worsen the existing mercury problem in the Everglades. Accordingly, operating permits stipulated that flow-through operation of these treatment cells could not begin until concentrations of THg and MeHg in the interior marsh were not significantly greater than corresponding concentrations in the supply canal. Cells 2 and 3 quickly met the start-up criteria in the fall of 2000. In contrast, Cell 1 exhibited anomalously high MeHg concentrations in the fall of 2000 and 2001, and the summer of 2002. During the last such event, water-column concentrations in Cell 1 reached 32 ng THg/L and an unprecedented 20 ng MeHg/L. Tissue Hg in resident fishes reached levels as high as 430 ng/g in mosquitofish, Gambusia holbrooki, 930 ng/g in sunfish, Lepomis spp., and 2000 ng/g in largemouth bass, Micropterus salmoides. Guided by results from the monitoring program, flow rate and water depth were managed as a means to alter sulfur biogeochemistry and, thereby, reduce in situ mercury methylation. This adaptive management strategy likely played a role in the decline in water-column concentrations of THg and MeHg in Cell 1 by late 2002 and the subsequent declines in tissue Hg levels in resident fishes. Cell 1 finally met formal start-up criteria on November 26, 2002.

Animals↗
PubMed1986

Enamel-fluoride levels in deciduous and permanent teeth of children in high, medium and low fluoride areas.

The surface enamel-fluoride concentration (approximately 4 microns) of both deciduous and permanent teeth of the central upper incisors were determined in 5-7 and 11-13-year-old children, who were born and bred in isolated areas with naturally high (3.7 parts/10(6)), medium (0.6 parts/10(6)) and low (less than 0.1 parts/10(6)) fluoride in the drinking water. Samples were taken in vivo by an acid-etch procedure and fluoride levels measured with an adapted fluoride-ion selective electrode. There were no significant differences in the fluoride concentrations or between etching depths between boys and girls, none between the contralateral incisors nor between the etching depths of deciduous and permanent teeth either in a single area or the three different ones. However, a highly-significant difference (p less than 0.01) was found in the enamel fluoride levels between the deciduous and permanent teeth in a fluoride area or among the three different fluoride areas. The ratio of the mean enamel fluoride concentration of permanent teeth to that of deciduous teeth increased with rise in fluoride in the drinking water. It is concluded that the different lengths of time, during which the crowns of deciduous and permanent incisor mineralize, contribute to this differing ratio.

Adolescent↗
PubMed2000

Accuracy of estimating time to collision using only monocular information in unilaterally enucleated observers and monocularly viewing normal controls.

Since individuals who have lost an eye in early life rely on monocular information, one asked if they would better estimate the time to collision (TTC) with an approaching object based on the monocular cue [(θ/(dθ/dt), i.e. tau] than a control group using only monocular information. Estimates of TTC were measured with a simulated approaching textured object using a staircase procedure. Seven adult observers who were unilaterally enucleated at an early age were compared with 18 normally sighted control observers who viewed the stimuli monocularly. Consistent with previous findings, the majority of the controls (13/18) underestimated TTC. Three enucleated observers had larger estimation errors than the 95% confidence interval of the mean of the control group. One enucleated observer was unable to give reliable results. These results suggest that unilaterally enucleated observers cannot estimate TTC more accurately (and may even be worse) than normal controls when estimates are based on monocular information alone. Further, the majority (83%) of enucleated observers were influenced by perceived distance information derived from the object's initial size when estimating TTC with an approaching object. The use of this other optical variable could account for their reduction in performance. It was suggested that in every day life enucleated individuals make use of as many optical variables as possible to partially compensate for the lack of binocularity.

Adaptation, Physiological↗
PubMed1999

Revisiting motion repulsion: evidence for a general phenomenon?

Previous studies have found large misperceptions when subjects are reporting the perceived angle between two directions of motion moving transparently at an acute angle, the so called motion repulsion. While these errors have been assumed to be caused by interactions between the two directions present, we reassessed these earlier measurements taking into account recent findings about directional misperceptions affecting the perception of single motion (reference repulsion). While our measurements confirm that errors in directional judgments of transparent motions can indeed be as big as 22 degrees we find that motion repulsion, i.e. the interaction between two directions, contributes at most about 7 degrees to these errors. This value is comparable to similar repulsion effects in orientation perception and stereoscopic depth perception, suggesting that they share a common neural basis. Our data further suggest that fast time scale adaptation and/or more general interactions between neurons contribute to motion repulsion while tracking eye movements play little or no role. These findings should serve as important constraints for models of motion perception.

Adaptation, Psychological↗
PubMed2003

Homeopathic practitioner views of changes in patients undergoing constitutional treatment for chronic disease.

OBJECTIVES: To identify areas that classical homeopathic practitioners would want to see evaluated in a patient self-report questionnaire sensitive to change during constitutional treatment. DESIGN: Open-ended, written practitioner questionnaire, analyzed using inductive content analysis. SETTINGS/LOCATION: Two classical homeopathic meetings held in the western United States. SUBJECTS: Homeopathic practitioners attending the above professional meetings and volunteering to complete the questionnaire in response to announcements prior to sessions. DATA COLLECTION METHODS: Practitioners completed a demographic questionnaire and answered an open-ended question inquiring for changes about which to ask people undergoing classical homeopathic constitutional treatment. RESULTS: The categories that the 38 homeopaths identified included changes in: (1) emotions; (2) mentation; (3) specific physical functioning; (4) general physical changes; (5) perception of self; (6) relationships; (7) spirituality; (8) lifestyle; (9) energy; (10) dream content and tone; (11) well-being; (12) perceptions by others; (13) life relationships; (14) a sense of freedom or feeling less "stuck"; (15) sleep; (16) coping; (17) ability to adapt; (18) creativity; and (19) recall of past experiences. Sixteen percent (16%) of participants added more in-depth description of the nature of changes across categories (i.e., a rhythmical process of innovation and flux). CONCLUSIONS: The findings are consistent with the systemic orientation of classical homeopathic philosophy to evaluate and treat the patient as a whole. Taken together, the results support the need for development of new, multidimensional outcome measures for clinical research in homeopathy beyond the disease-specific and health-related quality-of-life scales available from conventional medical research.

Activities of Daily Living↗
PubMed2005

Testing the exportability of a tool for detecting operational problems in VA teaching clinics.

BACKGROUND: Recurrent operational problems in teaching clinics may be caused by the different medical preferences of patients, residents, faculty, and administrators. These preference differences can be identified by cultural consensus analysis (CCA), a standard anthropologic tool. OBJECTIVE: This study tests the exportability of a unique CCA tool to identify site-specific operational problems at 5 different VA teaching clinics. DESIGN: We used the CCA tool at 5 teaching clinics to identify group preference differences between the above groups. We averaged the CCA results for all 5 sites. We compared each site with the averages in order to isolate each site's most anomalous responses. Major operational problems were independently identified by workgroups at each site. Cultural consensus analysis performance was then evaluated by comparison with workgroup results. PARTICIPANTS: Twenty patients, 10 residents, 10 faculty, members, and 10 administrators at each site completed the CCA. Workgroups included at minimum: a patient, resident, faculty member, nurse, and receptionist or clinic administrator. APPROACH: Cultural consensus analysis was performed at each site. Problems were identified by multidisciplinary workgroups, prioritized by anonymous multivoting, and confirmed by limited field observations and interviews. Cultural consensus analysis results were compared with workgroup results. RESULTS: The CCA detected systematic, group-specific preference differences at each site. These were moderately to strongly associated with the problems independently identified by the workgroups. The CCA proved to be a useful tool for exploring the problems in depth and for detecting previously unrecognized problems. CONCLUSIONS: This CCA worked in multiple VA sites. It may be adapted to work in other settings or to better detect other clinic problems.

Ambulatory Care Facilities↗
PubMed2006

Oxygen distribution in the mouse retina.

PURPOSE: To make the first measurements of intraretinal oxygen distribution in the mouse, an animal model of increasing importance in ophthalmic research. METHODS: Oxygen-sensitive microelectrodes were used to measure oxygen tension as a function of depth through the retina and choroid in anesthetized mice (n = 8). All measurements were performed under light-adapted conditions, with the animals spontaneously inspiring room air. The oxygen distribution in the avascular portion of the outer retina was analyzed by an established three-layer mathematical model that determines outer retinal oxygen consumption. RESULTS: The intraretinal oxygen distribution in the inner retina in individual profiles was often characterized by sharp peaks associated with elements of the retinal microvasculature, but, in the outer retina, the oxygen distribution was much more predictable and reflected the high oxygen uptake of the photoreceptors. Average choroidal oxygen tension was 42.0 +/- 1.2 mm Hg (mean +/- SE), and P(O2) at the surface of the retina was 21.7 +/- 0.8 mm Hg. The average minimum oxygen tension in the outer retina was 4.2 +/- 0.5 mm Hg. Average outer retinal oxygen consumption in the mouse was 193.3 +/- 10.6 nL O2/min per square centimeter, which is similar to that previously reported in the outer retina in vascularized areas of retina in the rat and monkey using similar techniques. CONCLUSIONS: The intraretinal oxygen distribution in the mouse is qualitatively and quantitatively similar to that in other species with vascularized retinas. The rate of oxygen consumption in the outer retina is also similar. These baseline data can now be used in studies employing mouse models of retinal disease.

Animals↗
PubMed1994

Characterization of region Ic in site I on human serum albumin. Microenvironmental analysis using fluorescence spectroscopy.

Characteristics of region Ic among at least three overlapping binding regions (regions Ia, Ib and Ic) in site I on human serum albumin (HSA) were analysed using n-alkyl p-aminobenzoates (n-alkyl p-ABEs), all of which are specific fluorescent probes for region Ic. In the interaction processes between n-alkyl p-ABEs and HSA, hydrophobic interaction, van der Waals interaction and local structural changes in region Ic were found to be involved based on the results obtained by analyses of the fluorescence spectra, structure-activity relationships and thermodynamic parameters. In addition, comparison of the fluorescence spectra of n-alkyl p-ABEs in HSA and detergents indicated that the possibility of a hydrophobic region Ic around which an amino acid with cationic charge locates could not be denied because of the similarity of fluorescence spectra between n-alkyl p-ABEs in HSA and in neutral and cationic detergents. The deviation of n-alkyl p-ABEs with long alkyl chains (C9-C12) in the relationships between association constants and physicochemical properties of a series of n-alkyl p-ABEs (C1-C12) suggested that region Ic possess an optimal depth. A conformational change of HSA with increasing pH (pH 6-9) generated an increase in hydrophobicity and adaptability of the binding region and made interaction easy, with an increase in adaptability of the binding region Ic; consequently, it enhanced the binding of n-alkyl p-ABEs to HSA.

Binding Sites↗
PubMedDate not supplied

Living in limbo--patients with cystic fibrosis waiting for transplant.

Lung transplant for patients with end-stage cystic fibrosis (CF) in the UK is recognized as the only successful treatment for CF patients with advanced lung disease. This study uses an exploratory approach to examine how patients with CF and their carers cope with the rigours of chronic illness and life on a transplant waiting list. Eight patients with CF, four awaiting transplant and four who had been transplanted within the previous 3 years, along with five of their carers, were asked to recount their experiences using a semi-structured interview technique. Four themes emerged from the interview data; displacement, disorder, life in limbo and readjustment to wellness. Support appears to be particularly important to patients and families after false alarms occur, and upon return home after transplant. The small sample size precludes generalization of the results to all patients with CF but gives an in-depth insight into the lived experience of waiting for transplant.

Adaptation, Psychological↗
PubMed1996

Stress among general practitioners and their spouses: a qualitative study.

BACKGROUND: Although research has been carried out on stress in general practitioners, little is known about the stresses experienced by their spouses. AIM: This study was undertaken to identify specific pressures at work and at home experienced by general practitioners and their spouses and to highlight their coping strategies. METHOD: In-depth interviews were conducted with 25 general practitioners and their spouses in the north-west of England. RESULTS: The doctors' increased workload and decreased interest in their family are important stressors for the entire family unit. Other stressors include time pressure, out-of-hours on-call, lack of support and amount of paperwork. General practitioners work late in the surgery, bring work home and spend time away from home at meetings. Family life is constantly interrupted by telephone calls. Role conflict was one of the major sources of stress for women general practitioners. Doctors' wives expressed concern regarding their husbands' excessive commitment to work and problems with communication. CONCLUSION: Recent changes to contractual working conditions have caused general practitioners to focus their energies on their practice instead of paying attention to the needs of their family. Male general practitioners leave the bulk of responsibility for running the family and household to their wives, but women general practitioners appear to maintain domestic responsibility while spending as much time in medical practice as their male colleagues. This is only an exploratory study based on a small sample, and so the findings cannot be generalized; however, it provides in-depth information on stress among general practitioners and their spouses.

Adaptation, Psychological↗
PubMed1999

Adaptive evolution of color vision of the Comoran coelacanth (Latimeria chalumnae).

The coelacanth, a "living fossil," lives near the coast of the Comoros archipelago in the Indian Ocean. Living at a depth of about 200 m, the Comoran coelacanth receives only a narrow range of light, at about 480 nm. To detect the entire range of "color" at this depth, the coelacanth appears to use only two closely related paralogous RH1 and RH2 visual pigments with the optimum light sensitivities (lambdamax) at 478 nm and 485 nm, respectively. The lambdamax values are shifted about 20 nm toward blue compared with those of the corresponding orthologous pigments. Mutagenesis experiments show that each of these coadapted changes is fully explained by two amino acid replacements.

Adaptation, Physiological↗
PubMed2003

Effects of enteral arginine supplementation on the structural intestinal adaptation in a rat model of short bowel syndrome.

The nitric oxide precursor L-arginine (ARG) has been shown to influence intestinal morphology and intestinal absorptive function. The purpose of the present study was to determine the effect of enteral ARG supplementation on structural intestinal adaptation, cell proliferation, and apoptosis in a rat model of short bowel syndrome (SBS). Thirty male Sprague-Dawley rats were divided into three experimental groups: Sham rats underwent bowel transection, SBS rats underwent 75% small bowel resection, and SBS-ARG rats underwent bowel resection and were treated with ARG given in the drinking water (2%). Parameters of intestinal adaptation, enterocyte proliferation and enterocyte apoptosis were determined on day 14 following operation. We have demonstrated that SBS-ARG animals had a lower jejunal and ileal mucosal weight, jejunal mucosal DNA and protein, ileal mucosal protein, jejunal villus height, jejunal and ileal crypt depth, and enterocyte proliferation index and a greater enterocyte apoptosis compared to SBS untreated animals. We conclude that in a rat model of SBS enteral L-arginine inhibits structural intestinal adaptation. Possible mechanism for this effect may be decreased cell proliferation and increased cell apoptosis.

Animals↗
PubMed1998

[Endosseous implant management of tumor patients with the bone lock system. A 5-year study].

The implantologic rehabilitation of patients after ablative oral tumour surgery and defect reconstruction is carried out generally without strict assessment of the successfulness of the outcome. Therefore 210 dental implants inserted in 58 tumour patients were subjected to regular follow-up examinations for 5 years. The Bone-Lock osseointegrated implant system (Howmedica Leibinger, Freiburg) was used exclusively. The plaque index (Silness and Löe), the sulcus bleeding index (Löe), the pocket probing depth, the width of the passive peri-implant tissue, implant mobility by means of the Periotest method and bone resorption according to X-ray findings were ascertained. At 60-70% of measurement points a passive peri-implant tissue was created. After the beginning of loading, specific adaptation phenomena of tumour patients could be detected. Despite constant plaque accumulation (mean 1.79), the bleeding disposition diminished from maximal 1.83 to 0.71. Corresponding to this finding the pocket probing depths decreased from 5.75 mm to 4.57 mm. The implant mobility (Periotest method: mean 2.25, range -3 to +8.5) showed a decrease in the first 2 years, then the values increased. The mobility depends on the kind of supraconstruction. Ball attachments have the lowest and implant-supported bridges have the highest values. Peri-implant bone resorption showed 1.43 mm as a mean value of all measurements and had a horizontal component of 73-84%. In accordance with this the vertical bone loss was small. After an increase during the first 2 years both values reached a steady state around 2.5 mm. The success rate for all 210 inserted implants is 83.2%. For implants in place for over 365 days the success rate is 93%. Prosthetic restoration in tumour patients can be achieved with osseointegrated dental implants according to the acknowledged international standards.

Adult↗
PubMed1998

Display duration and stereoscopic depth discrimination.

We investigated the role of display duration in stereoscopic depth perception. The display consisted of a dynamic random-dot stereogram, with two disparity-defined squares (1.9 degrees x 1.9 degrees), one on the left and one on the right of a central (Nonius) fixation stimulus. The sign of the disparity (crossed or uncrossed) was always the same for both squares, and the magnitude of disparity was 0.25 degree for one square and either 0.125 degree or 0.375 degree for the other square. Participants indicated which square appeared closer. The display duration was varied adaptively between 20 and 1000 ms until participants performed at 75% accuracy. Results confirmed large individual differences in the display duration required for stereoscopic depth perception. Approximately half of the 100 naive participants were able to perform the task at 20 ms, while the remaining participants required up to 1000 ms to perform at criterion. The present study shows that display duration is a critical variable in explaining wide differences in reported abilities of individuals to process stereoscopic depth information.

Adult↗