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Biomedical subjects

Javier Romero

Publications and source records attributed to Javier Romero.

17 recordsLinked to original sources
PubMed2006

Variation in multiple traits of vegetative and reproductive seagrass tissues influences plant-herbivore interactions.

Plant-herbivore interactions have strong ecological and evolutionary consequences, but have been traditionally overlooked in marine higher plants. Despite recent advances in seagrass ecology that highlight the importance of herbivory, the mechanisms that regulate the feeding behaviour of seagrass consumers remain largely unknown. Herbivores have been shown to reduce the sexual reproductive success of seagrasses through direct consumption of inflorescences and seeds, but we know little about intraspecific variation in susceptibility to grazing of different seagrass tissues. We contrasted the relative palatability of reproductive and vegetative tissues of the temperate seagrass Posidonia oceanica in the field, and we assessed the feeding preferences among these tissues of the main consumers of the plant, the fish Sarpa salpa and the urchin Paracentrotus lividus. Moreover, we identified the plant traits that explained the observed feeding behaviour. We provide strong evidence for herbivore selectivity among seagrass tissues. In the field, 70-90% of inflorescences were damaged by herbivores compared to 3-60% of leaves of similar age. In feeding assays, the urchin P. lividus showed over a twofold preference for reproductive tissue at various stages of development. By contrast, we detected no feeding activity on either leaves or inflorescences from the fish S. salpa, which is known to migrate to deeper waters soon after flowering starts and during the period of fruit maturation. Despite being the preferred food of urchins, inflorescences were chemically defended, had higher levels of phenolics and lower nutrient and calorific content than leaves. We experimentally demonstrated that leaf structural defences are the primary factor in determining urchin feeding preferences. Removal of plant structure results in a drastic shift in urchin selectivity towards the most nutritious and less chemically defended leaf tissue, indicating that multiple mechanisms of defence to herbivory may coexist in seagrasses.

Alismatales↗
PubMed2006

Risk factors for mortality among patients with extrapulmonary tuberculosis at an academic inner-city hospital in the US.

Despite an overall decrease in numbers of tuberculosis (TB) cases in the US, the proportion of extrapulmonary TB cases has increased. The study objective was to determine the most important predictors of all-cause mortality among patients with extrapulmonary TB. A retrospective chart review of adult extrapulmonary TB cases registered between 01/1995 and 12/2001 at Grady Memorial Hospital (a 1,000 bed, public inner-city hospital in Atlanta) was performed. Risk factors for death within 12 months after diagnosis of extrapulmonary TB were identified in multivariate analysis using log-binomial regression model. A total of 212 cases of extrapulmonary TB were identified; 100 (47%) were HIV-infected. The majority of patients were male (68%) and African-American (84%); mean age was 40 years. The most common sites of extrapulmonary TB were: lymph node (26%), pleural (21%), disseminated (20%), and central nervous system (CNS) or meningeal (16%). All-cause mortality rate in patients with extrapulmonary TB was 15% (21% among HIV-seropositive and 9% among HIV-uninfected patients, p = 0.02). In multivariate analysis, independent predictors of mortality included disseminated disease (PR = 4.66, 95% CI 1.93-11.24) and CNS/meningeal extrapulmonary TB (PR = 4.29, 95% CI 1.78-10.33), controlling for HIV infection. Extrapulmonary TB continues to be a persistent problem in the inner city and is associated with high mortality rates, especially among HIV-infected. Disseminated disease and the presence of CNS/meningeal TB are associated with poor prognosis.

Adult↗
PubMed2006

A multivariate index based on the seagrass Posidonia oceanica (POMI) to assess ecological status of coastal waters under the water framework directive (WFD).

We propose here a multivariate index based on structural and functional attributes of the Posidonia oceanica ecosystem (Posidonia oceanica multivariate index: POMI) to assess the ecological status of coastal waters following WFD requirements. POMI is based on the combination, through principal component analysis, of physiological, morphological, structural and community level seagrass descriptors (or metrics), univocally related to environmental quality. Scores on the first axis are normalised to a 0-1 scale (EQR) using reference and worst sites. The index was tested by sampling 22 seagrass beds in the Catalan coast (ca. 500 km, NW Mediterranean). The results show a clustering of variables on both sides of the first axis of the PCA, indicating a common relation of all metrics with ecological status. Moreover, the values (EQR) obtained reflect human pressure levels. The proposed index allows a practical and relatively simple assessment of the ecological status of coastal waters, and contains a considerable amount of ecological information, which can be useful for managing purposes.

Alismatales↗
PubMed2006

Enzymatic removal of free and conjugated sterols forming pitch deposits in environmentally sound bleaching of eucalypt paper pulp.

Free and conjugated sterols are among the main compounds responsible for pitch deposition in the manufacture of wood chemical pulps, making difficult the implementation of totally chlorine free bleaching (TCF) and closure of bleach plant circuits. In this work, the suitability of oxidative enzymes in efficiently removing sterols from eucalypt pulps is revealed. The enzymatic treatment was applied as an additional stage of an industrial-type TCF sequence for bleaching eucalypt kraft pulp. The pulp obtained after oxygen delignification was treated with a high-redox potential and thermostable fungal laccase using 1-hydroxybenzotriazole as an enzyme mediator. This pulp was further submitted to chelation and peroxide stages and compared with a control TCF pulp obtained using chemical reagents. The composition of the lipophilic extractives in the pulps and the corresponding liquids after the different stages was analyzed by gas chromatography and gas chromatography--mass spectrometry. Free sitosterol and sitosterol esters and glucosides, the major lipophilic compounds in eucalypt pulps, were completely removed during the laccase-mediator treatment. Only some intermediate products from sitosterol oxidation remained after the laccase stage, as well as in the final pulp. Pulp brightness was also improved due to the simultaneous removal of lignin by the laccase-mediator treatment.

Chromatography, Gas↗
PubMed2006

HIV/AIDS patients who move to urban Florida counties following a diagnosis of HIV: predictors and implications for HIV prevention.

We characterized patients at publicly funded HIV/AIDS patient treatment sites who moved ("migrated") post-diagnosis of HIV to five urban Florida counties, by geographic, demographic, socioeconomic and risk variables. Each patient who came for services at the sites in a 2-3 week sampling period was asked to complete a brief, self-administered questionnaire. We compared migrant with non-migrant patients to disclose characteristics predictive of migration and help plan for continuity of HIV care, future funding, and HIV prevention. Overall, 25% (range by site, 20%-38%) of the 1,286 patients in the study migrated to the counties from a non-contiguous Florida county, another state, or another country. In a multivariate model comparing interstate migrants with non-migrants, white and Hispanic race/ethnicity, age 9-29 years at first HIV diagnosis compared with older age, increasing education, highest current income and exposure category (men having sex with men and injection drug users) were independently associated with migration (all p < 0.05). In a similar model for international migrants, the independently associated variables included Hispanic ethnicity, education, and younger age at first HIV diagnosis. Although migrating can bring benefits to a patient such as improved access to health care or a new employment opportunity, it is stressful because it can result in changes in a person's social network, employment, and health care providers. Thus, moving could create unique patient needs concerning medication adherence, risk-taking, and other psychosocial needs. Given the high percentage of migrants in these urban Florida county clinics, these needs should be further examined and addressed.

Adolescent↗
PubMed2005

Designing a practical system for spectral imaging of skylight.

In earlier work [J. Opt. Soc. Am. A 21, 13-23 (2004)], we showed that a combination of linear models and optimum Gaussian sensors obtained by an exhaustive search can recover daylight spectra reliably from broadband sensor data. Thus our algorithm and sensors could be used to design an accurate, relatively inexpensive system for spectral imaging of daylight. Here we improve our simulation of the multispectral system by (1) considering the different kinds of noise inherent in electronic devices such as change-coupled devices (CCDs) or complementary metal-oxide semiconductors (CMOS) and (2) extending our research to a different kind of natural illumination, skylight. Because exhaustive searches are expensive computationally, here we switch to a simulated annealing algorithm to define the optimum sensors for recovering skylight spectra. The annealing algorithm requires us to minimize a single cost function, and so we develop one that calculates both the spectral and colorimetric similarity of any pair of skylight spectra. We show that the simulated annealing algorithm yields results similar to the exhaustive search but with much less computational effort. Our technique lets us study the properties of optimum sensors in the presence of noise, one side effect of which is that adding more sensors may not improve the spectral recovery.

Journal Article↗
PubMed2005

Multispectral synthesis of daylight using a commercial digital CCD camera.

Performance of multispectral devices in recovering spectral data has been intensively investigated in some applications, as in spectral characterization of art paintings, but has received little attention in the context of spectral characterization of natural illumination. This study investigated the quality of the spectral estimation of daylight-type illuminants using a commercial digital CCD camera and a set of broadband colored filters. Several recovery algorithms that did not need information about spectral sensitivities of the camera sensors nor eigenvectors to describe the spectra were tested. Tests were carried out both with virtual data, using simulated camera responses, and real data obtained from real measurements. It was found that it is possible to recover daylight spectra with high spectral and colorimetric accuracy with a reduced number of three to nine spectral bands.

Journal Article↗
PubMed2004

Spectral-reflectance linear models for optical color-pattern recognition.

We propose a new method of color-pattern recognition by optical correlation that uses a linear description of spectral reflectance functions and the spectral power distribution of illuminants that contains few parameters. We report on a method of preprocessing color input scenes in which the spectral functions are derived from linear models based on principal-component analysis. This multichannel algorithm transforms the red-green-blue (RGB) components into a new set of components that permit a generalization of the matched filter operations that are usually applied in optical pattern recognition with more-stable results under changes in illumination in the source images. The correlation is made in the subspace spanned by the coefficients that describe all reflectances according to a suitable basis for linear representation. First we illustrate the method in a control experiment in which the scenes are captured under known conditions of illumination. The discrimination capability of the algorithm improves upon the conventional RGB multichannel decomposition used in optical correlators when scenes are captured under different illuminant conditions and is slightly better than color recognition based on uniform color spaces (e.g., the CIELab system). Then we test the coefficient method in situations in which the target is captured under a reference illuminant and the scene that contains the target under an unknown spectrally different illuminant. We show that the method prevents false alarms caused by changes in the illuminant and that only two coefficients suffice to discriminate polychromatic objects.

Journal Article↗
PubMed2004

Spectral-daylight recovery by use of only a few sensors.

Linear models have already been proved accurate enough to recover spectral functions. We have resorted to such linear models to recover spectral daylight with the response of no more than a few real sensors. We performed an exhaustive search to obtain the best set of Gaussian sensors with a combination of optimum spectral position and bandwidth. We also examined to what extent the accuracy of daylight estimation depends on the number of sensors and their spectral properties. A set of 2600 daylight spectra [J. Opt. Soc. Am. A 18, 1325 (2001)] were used to determine the basis functions in the linear model and also to evaluate the accuracy of the search. The estimated spectra are compared with the original ones for different spectral daylight and skylight sets of data within the visible spectrum. Spectral similarity, colorimetric differences, and integrated spectral irradiance errors were all taken into account. We compare our best results with those obtained by using a commercial CCD, revealing the CCD's potential as a daylight-estimation device.

Journal Article↗
PubMed2003

Color and luminance asymmetries in the clear sky.

A long-standing assumption about the clear sky is that its colors and luminances are distributed symmetrically about the principal plane. As useful as this approximation is, our digital-image analyses show that clear-sky color and luminance routinely depart perceptibly from exact symmetry. These analyses reconfirm our earlier measurements with narrow field-of-view spectroradiometers [J. Opt. Soc. Am. A 18, 1325 (2001)], and they do so with much higher temporal and angular resolution across the entire sky dome.

Journal Article↗
PubMed2003

Cadaveric organ donor recruitment at Los Angeles County Hospital: improvement after formation of a structured clinical, educational and administrative service.

BACKGROUND/AIMS: There remains a critical shortage of cadaveric organs. At a large inner city level one trauma centre, several strategies were devised and combined to (a). optimize the physiologic status of potential donors, (b). promote awareness of the donation process among health care professionals and (c). perform quality control on the organ donation system - all in an effort to improve organ donation rates. Resuscitative and maintenance protocols were devised and implemented through a multidisciplinary team approach for patients diagnosed with brain death. We report the effect this approach has had on organ donation in a single centre. METHOD: A death record review (DRR) by the local organ procurement agency (OPO) was used to identify the number of patients diagnosed with brain death at Los Angeles County Hospital each year from 1995 through 2001. Data were collected to determine the number of these potential donors that eventually underwent organ donation. Data were collected for two time intervals: Phase I (1995-98) and Phase II (1999-2001). During Phase I, there was no focused institutional programme for the approach to potential donors. During Phase II, an institutional programme including the following characteristics was implemented: 1). donor resuscitation protocol, 2). assignment of a dedicated OPO coordinator liaison to interact with families, hospital personnel and the coroner's office, 3). assignment of the primary role of stabilization and care of potential donors and the integration of all medical services to the trauma service, and 4). biweekly conferences to review policies, protocols, and outcomes of donor management strategies. RESULTS: From 1995 to 2001 there was a large increase in patient referrals for donor evaluation from 86 (Phase I) to 124 (Phase II). There was a smaller increase in the number of suitable donors: Phase I (mean: 51/year) and Phase II (mean: 63/year). There was, however, an increase in the mean number of actual organ donors from 14.2/year to 25.7/year from Phase I to Phase II and an increase in organs donated from 29 to 49. Organ donor declines decreased from 53% (Phase I) to 39% (Phase II). CONCLUSIONS: Strategies to increase the number of cadaveric organs available for organ transplantation are crucial. A strategy combining prompt identification of potential organ donors, institution of resuscitative protocols, a multidisciplinary team approach, educational activities and utilization of personnel expert in organ procurement led to a marked increase in the number of organ donors and the number of organs donated at a single institution. Wider application of this approach should prove successful in increasing organ donation in a similar fashion in other institutions.

Cadaver↗
PubMed2003

Color-signal filtering in the Fourier-frequency domain.

We have analyzed the Fourier-frequency content of spectral power distributions deriving from three types of illuminants (daylight, incandescent, and fluorescent) and the color signals from both biochrome and nonbiochrome surfaces lit by these illuminants. As far as daylight and the incandescent illuminant are concerned, after filtering the signals through parabolic (low-pass) filters in the Fourier-frequency domain and then reconstructing them, we found that most of the spectral information was contained below 0.016 c/nm. When fluorescent illuminants were involved, we were unable to recover either the original illuminants or color signals to any satisfactory degree. We also used the spectral modulation sensitivity function, which is related to the human visual system's color discrimination thresholds, as a Fourier-frequency filter and obtained consistently less reliable results than with low-pass filtering. We provide comparative results for daylight signals recovered by three different methods. We found reconstructions based on linear models to be the most effective.

Journal Article↗
PubMed2002

Visceral vascular injuries.

This article deals with injuries to the celiac trunk, superior and inferior mesenteric arterial injuires. Surgical approaches and physiological implications of interruption of the mesenteric arterial circulation are addressed in detail. Surgical techniques for the management of these injuries and the need for second look operations are also examined.

Abdominal Injuries↗
PubMed2002

The Medtronic Intact bioprosthesis: clinical and hemodynamic performance over 13 years.

We evaluated our results over 13 years with the aortic-position Medtronic Intact bioprosthesis. Our study involved 91 consecutive patients with isolated aortic valve replacement with the Medtronic Intact bioprosthesis. The follow-up was complete for 95%. Mean follow-up was 6.61 years (range 16 days-13 years), 590 patient years. Early mortality rate was 3.3%. Late mortality was 23 patients. Survival at 13 years was 53.52% (SD = 7.63%). The linearized rate of major thromboembolism was 0.34% per patient year; rate of major bleeding events was 0.33% per patient year. The rate of nonstructural dysfunction was 0.16% per patient year. Rate of reoperation was 0.53% and rate of structural valve deterioration was 0.16% per patient year. New York Heart Association (NYHA) postoperative classes were I to II in 92.21%. Gradients were as follows: 21 to 23.87 mm Hg, 23 to 18 mm Hg, 25 to 15.5 mm Hg, and 27 to 16.50 mm Hg. Structural valve deterioration was low during the 13 years of follow-up. Valve gradients and areas remained the same over the follow-up period. The Medtronic Intact bioprosthesis shows excellent clinical and hemodynamic performance at 13 years of follow up.

Adult↗
PubMed2002

Day for night: should we staff a trauma center like a nightclub?

Most trauma services throughout the country are staffed on a fixed-call rotational basis. Staff is deployed in a linear fashion when trauma often occurs in a skewed sporadic fashion resulting in large fluctuations in volume, injury severity, and mechanism of injury. Medical error and increased mortality have been associated with certain admission times. We reviewed 8015 consecutive major trauma admissions over a 3-year period. When reviewing aggregate data we found a significant difference in mortality between patients admitted during the day (7:00 AM to 6:59 PM) compared with those admitted at night (7:00 PM to 6:59 AM) (10.1% vs 13.1%, P < 0.01). On further analysis the two populations were found to be significantly different in volume, Injury Severity Score (ISS), and mechanism of injury. More patients were admitted at night and on weekends. They had a higher ISS, higher frequency of penetrating trauma, and a higher likelihood of undergoing operative intervention. Multiple subset analyses were performed stratifying for ISS, time of admission, day of admission, and mechanism of injury using mortality rate as the end point. Six comparisons were performed: 1) morning versus night admission; 2) weekday versus weekend admission; 3) least busy day (Tuesday) versus busiest day (Sunday) admission; 4) weeknight versus weekend night admission; 5) in cases of penetrating trauma, morning versus night admission; and 6) in cases of blunt trauma, morning versus night admission. None of the six comparisons showed a significant difference in mortality. There was no significant difference in ISS-matched mortality related to fixed trauma call staffing.

After-Hours Care↗