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PubMed2004

Additive effects of estrogen and mechanical stress on nitric oxide and prostaglandin E2 production by bone cells from osteoporotic donors.

Mechanical loading is thought to provoke a cellular response via loading-induced flow of interstitial fluid through the lacuno-canalicular network of osteocytes. This response supposedly leads to an adaptation of local bone mass and architecture. It has been suggested that loss of estrogen during menopause alters the sensitivity of bone tissue to mechanical load, thereby contributing to the rapid loss of bone. The present study aimed to determine whether estrogen modulates the mechanoresponsiveness of bone cells from osteoporotic women. Bone cell cultures from nine osteoporotic women (aged 62-90 years) were pre-cultured for 24 h with 10(-11) mol/l 17beta-estradiol (E2) or vehicle, and subjected to 1 h of pulsating fluid flow (PFF) or static culture. E2 alone enhanced prostaglandin E(2) (PGE(2)) and nitric oxide (NO) production by 2.8-fold and 2.0-fold, respectively, and stimulated endothelial nitric oxide synthase protein expression by 2.5-fold. PFF, in the absence of E2, stimulated PGE(2) production by 3.1-fold and NO production by 3.9-fold. Combined treatment with E2 and PFF increased PGE(2) and NO production in an additive manner. When expressed as PFF-treatment-over-control ratio, the response to fluid shear stress was similar in the absence or presence of E2. These results suggest that E2 does not affect the early response to stress in bone cells. Rather, E2 and shear stress both promote the production of paracrine factors such as NO and PGE(2) in an additive manner.

Aged↗

PubMed1997

Directionality of auditory nerve fiber responses to pure tone stimuli in the grassfrog, Rana temporaria. I. Spike rate responses.

We studied the directionality of spike rate responses of auditory nerve fibers of the grassfrog, Rana temporaria, to pure tone stimuli. All auditory fibers showed spike rate directionality. The strongest directionality was seen at low frequencies (200-400 Hz), where the spike rate could change by up to nearly 200 spikes s-1, with sound direction. At higher frequencies the directional spike rate changes were mostly below 100 spikes s-1. In equivalent dB SPL terms (calculated using the fibers' rate-intensity curves) the maximum directionalities were up to 15 dB at low frequencies and below 10 dB at higher frequencies. Two types of directional patterns were observed. At frequencies below 500 Hz relatively strong responses were evoked by stimuli from the ipsilateral (+90 degrees) and contralateral (-90 degrees) directions while the weakest responses were evoked by stimuli from frontal (0 degree or +30 degrees) or posterior (-135 degrees) directions. At frequencies above 800 Hz the strongest responses were evoked by stimuli from the ipsilateral direction while gradually weaker responses were seen as the sound direction shifted towards the contralateral side. At frequencies between 500 and 800 Hz both directional patterns were seen. The directionality was highly intensity dependent. No special adaptations for localization of conspecific calls were found.

Acoustic Stimulation↗

PubMed1997

General and local cold responses in humans after 2 weeks at high altitude.

To investigate the effects of a short-term high altitude residence (2 weeks between 4150 m and 6885 m in the Andes) on the general and local cold responses after descent, 11 subjects were submitted both to a whole body standard cold air test (SCAT, dry bulb temperature = 1 degree C, 2 h, nude, at rest) and to a local cold water test of the right upper limb (CWT, 5 degrees C, 5 min) both before and after the expedition. Compared to before the expedition, a lower systolic blood pressure was observed after the high altitude residence [130.00 (SEM 3.35) mm Hg vs 140.40 (SEM 4.74) mm Hg at the end of CWT, P < 0.05] whereas no significant change either in diastolic blood pressure or in heart rate was found. All skin temperatures of the right upper limb were lowered (P < 0.05). During SCAT, body temperatures were unchanged (rectal and mean skin temperature, Tsk) but metabolic heat production was slightly but significantly diminished [110 (SEM 4) W.m-2 vs 125 (SEM 3) W.m-2, P < 0.05] and heat debt increased [11.37 (SEM 1.11) kJ.kg-1 vs 9.30 (SEM 2.30) kJ.kg-1, P < 0.05]. Moreover, the time of onset of continuous shivering (d) was shortened [8.20 (SEM 1.90) min vs 17.30 (SEM 3.60) min, P < 0.05] and the level of Tsk observed at (d) was higher [25.70 (SEM 0.80) degrees C vs 23.57 (SEM 0.78) degrees C, P < 0.05] suggesting an increase in the sensitivity of the thermoregulatory system despite the slight decreased shivering activity observed. It was concluded that general and local cold tolerance were modified by a short-term residence at altitude and that the changes observed were not in accordance with general or (and) local cold adaptation. In contrast, high altitude sojourn could be a risk factor for frostbite of the extremities.

Altitude↗

PubMed2004

Geographic variation in the life history of the sagebrush lizard: the role of thermal constraints on activity.

Thermal constraints on the time available for activity have been proposed as a proximate mechanism to explain variation in suites of life history traits. The longer that an ectotherm can maintain activity, the more time it has to forage and the greater chance that it will encounter a predator and be eaten. Thus, the thermal environment may produce a trade off between growth and survival when variation in the environment favors increased activity. I used mark-recapture data from a demographic study of three natural populations of the sagebrush lizard (Sceloporus graciosus) and estimates of thermal opportunity for each population to evaluate whether variation in the thermal environment can explain patterns of growth and survival that occur over an elevational gradient. Lizards from the highest elevation population exhibited higher individual growth rates than those of lizards from lower elevation, while mortality rates increased with elevation for these populations. The covariation of fast growth and high mortality with increased thermal opportunity is the opposite trend expected if the thermal environment alone is to explain patterns of life history in these lizards. Additional factors including thermal heterogeneity in the distribution of microhabitats of lizards, adaptation to local environmental conditions, and a potential trade-off between resource acquisition and predation risk need to be addressed to obtain a satisfactory explanation of the causative mechanisms producing life history variation.

Animals↗

PubMed2006

Geographic variation in attraction to human odor compounds by Aedes aegypti mosquitoes (Diptera: Culicidae): a laboratory study.

Previous investigations of Aedes aegypti response to human odor components have revealed a number of compounds that attract host-seeking females. However, such studies have utilized only a small number of long-term laboratory Ae. aegypti colonies. Using laboratory y-olfactometers, we studied the attraction of four different Ae. aegypti populations (North Queensland, Australia; Florida, USA; Singapore; and Minas Gerais, Brazil) to a key attractant compound from human skin, lactic acid. Combinations of lactic acid with ammonia and a fatty acid (caproic acid) were also investigated. The aims were to determine the extent of variation in lactic acid dose response among populations and to see whether all four populations responded equally to combinations of human odor components. Although all Ae. aegypti populations were attracted to lactic acid, there were differences in the threshold dose: Florida 0.03 microg/min, Singapore 0.17 microg/min, North Queensland 1.92 microg/min, and Brazil 10.27 microg/min. Attraction to lactic acid alone (maximum <40%) was significantly lower than for human odor (>87% for all populations). Significant increases in attraction were observed when lactic acid was combined with ammonia or caproic acid, although not for all populations. In addition, the highest doses of caproic acid tested decreased attraction when combined with lactic acid. The divergent responses to host kairomones seen here may be evidence of adaptation to locally available hosts in different parts of the geographic range of Ae. aegypti.

Aedes↗

PubMed1980

Surveillance, prevention, and control of sexually transmitted agents associated with pelvic inflammatory disease.

Control and prevention of pelvic inflammatory disease would result from successful control of Neisseria gonorrhoeae and genital Chlamydia trachomatis infections. The same control system applies to both, but while this system is well documented in gonorrhea control, there is still no evidence that it is effective for C. trachomatis infections. Primary prevention of PID should be realized through a reduction of the incidence of gonorrhea, and the available techniques--(1) contact tracing and epidemiologic treatment, (2) screening and case finding, (3) preventive measures, (4) health education, and (5) training of the health workers--are discussed. Secondary prevention of PID can be achieved through good management of uncomplicated infections due to N. gonorrhoeae and C. trachomatis. The approach must be adapted to local conditions and should be different in developing countries with a specialized health care system for sexually transmitted disease. Good management of PID is crucial in preventing sequelae and most important are tracing and treating the male contacts of patients with PID. Measures of tertiary prevention attempt to rehabilitate the patient; the main sequelae after PID are ectopic pregnancy and infertility. Surgical techniques can restore tubal function, but these methods are complicated and have a low success rate.

Delivery of Health Care↗

PubMed1988

An experience of war surgery and wounds presenting after 3 days on the border of Afghanistan.

The International Committee of the Red Cross (ICRC) has run hospitals for the wounded of the conflict in Afghanistan since 1981. For political and geographical reasons the hospitals are situated in Pakistan, some distance from the fighting, and so the wounded may take many days to arrive. This has enabled a surgical team provided by the British Red Cross Society to observe wounds of varying age and degrees of putrefaction or healing. Twenty-nine (29) patients with wounds of 3 or more days are detailed. The old wounds showed a tendency either to putrefaction or healing and the surgical management had to be revised accordingly. Wounds sutured in the field tended to putrefy. Among the various problems, the most taxing and difficult were the cultural and religious objections to amputation. The ICRC is committed to providing surgical hospitals for the Afghan war wounded for as long as the conflict lasts. It has adapted the local facilities and staff to the particular political, geographical and cultural situation.

Adult↗

PubMed1991

EEG data compression with source coding techniques.

A data compression algorithm for the EEG, derived from the adaptive pulse code modulation scheme, is described where the consecutively computed differences are coded by passing them through a quantizer possessing only a few levels; the range of these levels is adapted to local signal statistics. Three different versions of the algorithm with data reduction up to 75% are presented. The system was validated using several multichannel-routine EEG recordings with both visual evaluation and computation of signal-to-noise ratios.

Algorithms↗

PubMedDate not supplied

Basic results for assessment of human ageing.

The study of collagen metabolism during the total life span of mammals has contributed greatly to the understanding of the human ageing process. Particularly relevant is the demonstration that these tissue dynamics of collagen in the whole organism is clearly age-dependent, but progresses non-synchronously in different organs. Thus, supply and degradation are tightly linked processes in all tissues, as in the case of other proteins, but the catabolic process regulates the turnover of already deposited collagen in adaptation to local needs. In the whole body there is a similar age-dependent interaction regarding the part of the organism whose activity is directly related with regulating functions mainly supporting the parenchyma, the other part of the organism to work as well as possible. It can be deduced that this regulation attains great importance in ageing because the capacity to survive is dependent on it. At the same time as we expose this dynamical conception of ageing we point out some ageing parameters from experimental gerontology capable of being applied in such a manner as to objectify human ageing manifestations. Furthermore, we propose a way to quantify total ageing on the basis of this interaction, as in a two-compartment system leading to one result which would mean vitality. We discuss related questions, mainly regarding the reference population as control and a good parameter selection which should represent total ageing manifestations in the human body.

Journal Article↗

PubMed1983

Biosynthesis of prostaglandins in microsomes of human skeletal muscle and kidney.

The capacity of human skeletal muscle, renal cortical and renal medullary microsomes to synthesize prostaglandins (PGs) from exogenous precursor was investigated. The microsomal fractions were incubated with [1-14C]-labelled arachidonate ([14C]-AA) in the absence and in the presence of reduced glutathione (GSH). [14C]-PGs formed in the incubates were extracted, separated by thin-layer chromatography and quantified using liquid scintillation spectrometry. [14C]-labelled PGE2, PGF2 alpha and 6-keto-PGF1 alpha were found to be the principal products of microsomal PG formation and appeared in similar relative quantities in the incubates of all three tissues studied. In some incubates of renal cortical and renal medullary microsomes formation of smaller relative amounts of [14C]-PGD2 and thromboxane B2 was also noted. In addition, formation of substantial amounts of a polar, not yet identified compound was frequently observed in all incubates. In the absence of GSH, [14C]-6-keto-PGF1 alpha was the main PG formed by microsomes of all of the three tissues. At the expense of 6-keto-PGF, the addition of GSH resulted in an almost 2-fold stimulation of [14C]-PGF2 alpha formation in the skeletal muscle and renal cortical incubates, whereas in the renal medullary incubates an increase in the relative amounts of [14C]-PGE2 was observed. The PG synthetic capacity was highest in the skeletal muscle and lowest in the renal cortical microsomes. The results demonstrate a considerable capacity of human skeletal muscle and of the renal cortex and renal medulla to synthesize prostacyclin. Furthermore, the data reveal GSH-dependent differences in the expression of PG biosynthesis in these tissues. The GSH-dependent differentiation of PG synthesis may reflect a mechanism of adaptation of local PG production to the physiological processes.

Aged↗

PubMed1987

Rural health care: a British success or a tale of unmet need?

Discussion over health needs and health care in the U.K. has mainly centered on the urban area. The countryside has not been included in this debate because it is assumed that rural people are healthier than their urban counterparts and that health and social services are more effective. This paper questions these two premises and shows higher than expected levels of illness in the rural area and the health services to be largely dependent on general practice which, like all rural services, is becoming increasingly centralised and inaccessible. What is needed, it is argued, is the construction of a case for more localised care. Not that this should necessarily lead to a singularly rural type of health service, rather that patterns of provision should be adapted to local needs wherever they are situated.

Family Practice↗

PubMed1995

Continuity and change in reproductive and abortion patterns of Soviet immigrants in Israel.

The abortion and fertility patterns of old-timer and new immigrants from the former Soviet Union in Israel are compared with those prevalent among the receiving population, where a different system of services, free-choice contraceptive means and outlooks on family size exist. High frequency of abortion in the U.S.S.R. looks adaptive to local circumstances rather than cultural, yet higher-than-average patterns of induced abortion and lower-than-average number of children persist after almost two decades. In the short range, new immigrants seem also to be exposed to very low fertility rates and to significant high rates of legal and illegal abortion than countrywide.

Abortion, Induced↗

PubMed1988

In vivo analysis of cortical amino acid neurotransmitters collected in the rat by a new double lumen push-pull catheter system.

The release of both endogenous and newly synthesized amino acid neurotransmitters was examined simultaneously in different areas of the cerebral cortex in the freely moving rat. An array of push-pull guide tubes was implanted permanently to rest above the frontal, parietal, temporal and occipital areas of the cortex of each rat. Then a new double-lumen catheter system, specially adapted for localized push-pull perfusion of the conscious animal, was used to perfuse an artificial cerebrospinal fluid at each cortical site. For the new synthesis experiments, 0.5 microCi of [14C]glucose in a volume of 2.0 microliter was first microinjected into the perfusion site as a precursor to label amino acids. After the site was perfused at a rate of 12.0 microliter/min, each of the samples was assayed by two-dimensional thin-layer chromatography. In a second analysis, the content of six endogenous amino acids present in unlabeled samples of push-pull perfusate was quantified by high-performance liquid chromatography analysis with electrochemical detection. The results showed a notable homogeneity among each of the four cortical areas in the content of four of the six amino acids examined. Endogenous glutamine exhibited the highest proportional content in the cortical perfusates, whereas glutamic acid was proportionally higher in terms of new synthesis. An anatomical analysis revealed that the level of endogenous glutamic acid in the frontal area was significantly lower than that found in the occipital or temporal regions of the rat's cortex. An opposite result was obtained when the proportional synthesis of glutamic acid from [14C] glucose was compared in different cortical regions in that a statistically higher release occurred in the frontal than in the occipital cortex.

Amino Acids↗

PubMed1989

Glucose metabolism and protein synthesis in stratified squamous epithelia from young and old mice.

Glucose metabolism in regionally distinct epidermis and oral epithelia of young adult and aged mice was studied using 5-3H glucose and differentially labelled 14C-glucose. The results obtained with 3H-glucose indicate there is active utilization of glucose by all the epithelia examined. However, an enhanced utilization of glucose was observed in old ear epidermis when compared to that in young mice. The measurements of respiratory 14CO2 in the young and old epidermis indicated that aerobic glycolysis was significantly greater in ear epidermis and buccal epithelium from old than from young mice. Pentose phosphate activity was significantly reduced in palate epithelium from old animals when compared with that of young animals. Incorporation of radioactively labelled leucine and histidine revealed some regional differences between the epithelia examined. However, no age-associated differences were observed in any of the tissues. It is concluded that the observed metabolic changes reflect regionally specific adaptations to local factors rather than representing a programmed biological event.

Aging↗

PubMed1991

The Three Rivers Regatta accident: an EMS perspective.

The Three Rivers Regatta accident occurred on August 7, 1988 when a Formula I racing craft collided with shore, injuring 24 spectators. The authors retrospectively examined the prehospital-based response for this multiple-casualty incident that used emergency medical service (EMS) physicians and 32 paramedics stationed at water and land-based posts to triage and evacuate 24 patients in 32 minutes. Patients were transported to 5 hospitals including 4 Level I trauma centers; this was accomplished in 53 minutes. The EMS response was unique in a number of respects. This was a prehospital-based rescue with the entire triage and stabilization phase accomplished by River Rescue units that transported paramedic divers, EMS physicians, and trauma supplies for 30 patients. Also of significance was the inordinate proportion of pediatric patients that accounted for 50% (12/24) of the cases. Successful medical care was the result of planning based on "Daily Routine Doctrine" or escalation of existing treatment protocol; adequate supplies, personnel and transport adapted to local geography and patient population; communications, including all services--EMS, police, and fire; and prehospital physician input to ensure correct triage order and patient disposition.

Accidents↗

PubMed1994

Reproductive health in central and eastern Europe: priorities and needs.

The countries in Central and Eastern Europe combine induced abortion as the method of choice for family planning with low contraceptive use (Hungary and Slovenia excepted). This widespread use of induced abortion has a negative influence on reproductive and general public health, and an effort should be made to introduce modern, effective family planning. Both information, education and communication (IEC) programmes (for the users) and training in contraceptive technology and counselling (for the providers) is badly needed, as well as a continuing supply of contraceptives. In order to design optimal programmes, more research into knowledge, attitude and practice with regard to sexuality, sexual behaviour and contraception is urgently needed. So far, little research into contraceptive behaviour and its determinants has been done in Central and Eastern Europe, but the few data that are available point towards a lack of contraceptive knowledge in both the population and amongst contraception providers. The cultural differences between Western and Eastern industrialized countries are often underestimated or ignored, but because of the special situation in the countries in Central and Eastern Europe, education programmes which were successful elsewhere in the world may not work in these countries and may require extensive adaption to local needs and customs. Alternatively, special education programmes need to be developed. Programmes, especially those addressing contraception, should be combined with a long-term commitment for support and the provision of contraceptives.

Abortion, Induced↗

PubMed1992

A chronic disease score from automated pharmacy data.

Using population-based automated pharmacy data, patterns of use of selected prescription medications during a 1 year time period identified by a consensus judgement process were used to construct a measure of chronic disease status (Chronic Disease Score). This score was evaluated in terms of its stability over time and its association with other health status measures. In a pilot test sample of high utilizers of ambulatory health care well known to their physicians (n = 219), Chronic Disease Score (CDS) was correlated with physician ratings of physical disease severity (r = 0.57). In a second random sample of patients (n = 722), its correlation with physician-rated disease severity was 0.46. In a total population analysis (n = 122,911), it was found to predict hospitalization and mortality in the following year after controlling for age, gender and health care visits. In a population sample (n = 790), CDS showed high year to year stability (r = 0.74). Based on health survey data, CDS showed a moderate association with self rated health status and self reported disability. Unlike self-rated health status and health care utilization, CDS was not associated with depression or anxiety. We conclude that scoring automated pharmacy data can provide a stable measure of chronic disease status that, after controlling for health care utilization, is associated with physician-rated disease severity, patient-rated health status, and predicts subsequent mortality and hospitalization rates. Specific methods of scoring automated pharmacy data to measure global chronic disease status may require adaptation to local prescribing practices. Scoring might be improved by empirical estimation of weighting factors to optimize prediction of mortality and other health status measures.

Adolescent↗

PubMed2005

Resting metabolic expenditure as a potential source of variation in growth rates of the sagebrush lizard.

Along an elevational gradient on SW Utah, sagebrush lizards (Sceloporus graciosus) exhibit an unexpected pattern of growth. Lizards from a high elevation population grow faster than lizards from two populations at lower elevations despite shorter daily and seasonal activity. Results from a common environment study of growth suggest that the differences in growth are not due to adaptation to local environmental conditions. In this study, I test the hypothesis that higher growth rates in lizards from high elevation may be attributable to reduced resting metabolic expenditure compared to that of lizards from populations at two lower elevations. Resting metabolic rates were measured for individuals from each of the study populations across different times of day and over a broad range of temperatures. Under the same laboratory conditions, field-caught lizards from the high elevation population exhibited lower metabolic rates when compared to lizards from lower elevations. Daily resting metabolic expenditures were calculated using the observed metabolic rates coupled with estimates of daily activity. Daily resting metabolic expenditure was 50% greater for individuals from the two lower elevation populations, which could result in 12.5% more energy that could be potentially allocated to growth for lizards from high elevation. Such energetic savings may be able to explain differences in the patterns of growth observed in nature.

Acclimatization↗