Dried blood spot analysis for elements of nutritional concern as demonstrated in studies of Galápagos land iguanas (Conolophus species).

BACKGROUND: Dried blood spot (DBS) technology is valuable in providing simple means of storing blood samples from wildlife with small blood volumes. Methods designed for heavy metal analysis on DBS become more useful if extended to elements of nutritional significance. PURPOSE: (1) Development of procedures for measuring Mn, Fe, Co, Cu, Zn, Se and Mo in DBS; (2) use the designed methods in health assessments of Galápagos land iguanas (Conolophus species). PROCEDURES: Elements were measured by inductively coupled plasma/mass spectrometry (ICP-MS) following acid digestion of whole blood or DBS from the same animal for direct comparison. Study animals comprised free-ranging iguanas from separate islands in the Galápagos archipelago. MAIN FINDINGS: DBS spikes (Mn, Fe, Co, Cu, Zn, Se and Mo) demonstrated accuracy to ∼100 ppb; reporting limits were set there except for Fe and Zn which were set at 1000 ppb. Plasma samples - generally preferable for nutritional element diagnostics - were submitted from Galápagos land iguanas along with DBS as part of a large-scale health assessment. In plasma versus DBS concentration comparisons, Fe, Cu, Se and Mn correlated well with R^2 values of 0.799, 0.818, 0.896 and 0.899, respectively, and slopes ranging 0.88 - 1.3. Co and Zn showed greater scatter. Mo had insufficient points above its reporting limit and offered advantages for toxicity assessments. Bland-Altman diagrams showed flat scatter between 2x standard deviation boundaries with no undue trends except for Mn which had few points above its reporting limit. Bias, defined as the average difference [DBS - plasma] divided by the average value, was relatively low throughout, with values of - 19.3 % (Fe), - 48.7 % (Co), - 19.6 % (Cu), - 6.9 % (Zn), - 21.4 % (Se) and + 40.7 % (Mn). Normal distribution assessment of iguana Cu, Zn, Se and Fe plasma values showed unanticipated divergences between two species. CONCLUSIONS: The DBS approach for nutritional element analysis offers a suitable methodology for determining crucial elements Mn, Fe, Co, Cu, Zn, Se, and Mo in veterinary samples. Analyses of samples from Conolophus species revealed interesting divergences particularly for Cu, Zn, Se and Fe, elements generally associated with defense against oxidative stress.

A Bayesian approach for mixed effects state-space models under skewness and heavy tails.

Human immunodeficiency virus (HIV) dynamics have been the focus of epidemiological and biostatistical research during the past decades to understand the progression of acquired immunodeficiency syndrome (AIDS) in the population. Although there are several approaches for modeling HIV dynamics, one of the most popular is based on Gaussian mixed-effects models because of its simplicity from the implementation and interpretation viewpoints. However, in some situations, Gaussian mixed-effects models cannot (a) capture serial correlation existing in longitudinal data, (b) deal with missing observations properly, and (c) accommodate skewness and heavy tails frequently presented in patients' profiles. For those cases, mixed-effects state-space models (MESSM) become a powerful tool for modeling correlated observations, including HIV dynamics, because of their flexibility in modeling the unobserved states and the observations in a simple way. Consequently, our proposal considers an MESSM where the observations' error distribution is a skew-t. This new approach is more flexible and can accommodate data sets exhibiting skewness and heavy tails. Under the Bayesian paradigm, an efficient Markov chain Monte Carlo algorithm is implemented. To evaluate the properties of the proposed models, we carried out some exciting simulation studies, including missing data in the generated data sets. Finally, we illustrate our approach with an application in the AIDS Clinical Trial Group Study 315 (ACTG-315) clinical trial data set.

Health status of the red-billed tropicbird (Phaethon aethereus) determined by hematology, biochemistry, blood gases, and physical examination.

The red-billed tropicbird, Phaethon aethereus, is a species of seabird native to the Galápagos archipelago, and widely distributed across the neotropics. General health, blood chemistry, and haematology parameters have not been published for this species. Blood analyses were performed on samples drawn from 51 clinically healthy red-billed tropicbirds captured from their burrows at Islote Pitt on San Cristóbal Island in July, 2016 (21) and Daphne Major Island in June, 2017 (30). In the field, a point of care blood analyser (iSTAT) was used to obtain results for HCO3-, pH, pCO2, pO2, TCO2, iCa, Na, K, Cl, Hb, HCT, anion gap, creatinine, glucose and urea nitrogen. Additionally, a portable Lactate PlusTM analyser was used to measure blood lactate, and blood smears were also created in situ. The blood slides were used to estimate leukocyte counts and 100-cell differentials. Alongside these biochemistry and haematology parameters, average heart rate, respiratory rate, body temperature and scaled mass index (calculated from weight and a body measurement) were compared to determine the standard measurements for a healthy individual. The baseline data, and reference intervals reported in this paper are essential to detecting changes in the health of red-billed tropicbirds in the future.

Prevalence of Toxoplasma gondii in Galapagos birds: Inference of risk factors associated with diet.

Toxoplasma gondii is a zoonotic intracellular parasite of particular concern in the conservation of wildlife due to its ability to infect all homeotherms and potentially cause acute fatal disease in naive species. In the Galapagos (Ecuador), an archipelago composed of more than a hundred islets and islands, the presence of T. gondii can be attributed to human-introduced domestic cats, but little is known about its transmission in wildlife populations. We compared the prevalence of antibodies against T. gondii in sympatric Galapagos wild bird species that differ in diet and contact with oocyst-contaminated soil to determine the relative importance of trophic habits as an exposure factor. Plasma samples were obtained from 163 land birds inhabiting Santa Cruz, one of the cat-inhabited islands, and from 187 seabirds breeding in cat-free surrounding islands (Daphne Major, North Seymour, and South Plaza). These samples were tested for the presence of T. gondii antibodies using the modified agglutination test (MAT ≥ 1:10). All seven species of land birds and 4/6 species of seabirds presented seropositive results. All great frigatebirds (Fregata minor) (N = 25) and swallow-tailed gulls (Creagrus furcatus) (N = 23) were seronegative. Prevalence ranged from 13% in Nazca boobies (Sula granti) to 100% in Galapagos mockingbirds (Mimus parvulus). It decreased from occasional carnivores (63.43%) to granivores-insectivores (26.22%), and strict piscivores (14.62%). These results indicate that the consumption of tissue cysts poses the highest risk of exposure to T. gondii for Galapagos birds, followed by the ingestion of plants and insects contaminated by oocysts as important transmission pathways.

Lack of genetic differentiation in yellowfin tuna has conservation implications in the Eastern Pacific Ocean.

Yellowfin tuna, Thunnus albacares, is an important global fishery and of particular importance in the Eastern Pacific Ocean (EPO). According to the 2019 Inter-American Tropical Tuna Commission (IATTC) assessment, yellowfin tuna within the EPO is a single stock, and is being managed as one stock. However, previous studies indicate site fidelity, or limited home ranges, of yellowfin tuna which suggests the potential for multiple yellowfin tuna stocks within the EPO, which was supported by a population genetic study using microsatellites. If numerous stocks are present, management at the wrong spatial scales could cause the loss of minor yellowfin tuna populations in the EPO. In this study we used double digestion RADseq to assess the genetic structure of yellowfin tuna in the EPO. A total of 164 yellowfin tuna from Cabo San Lucas, México, and the Galápagos Islands and Santa Elena, Ecuador, were analysed using 18,011 single nucleotide polymorphisms. Limited genetic differentiation (FST = 0.00058-0.00328) observed among the sampling locations (México, Ecuador, Peru, and within Ecuador) is consistent with presence of a single yellowfin tuna population within the EPO. Our findings are consistent with the IATTC assessment and provide further evidence of the need for transboundary cooperation for the successful management of this important fishery throughout the EPO.

Elevated Mercury Concentrations and Isotope Signatures (N, C, Hg) in Yellowfin Tuna (Thunnus albacares) from the Galápagos Marine Reserve and Waters off Ecuador.

We examined how dietary factors recorded by C and N influence Hg uptake in 347 individuals of yellowfin tuna (Thunnus albacares), an important subsistence resource from the Galápagos Marine Reserve (Ecuador) and the Ecuadorian mainland coast in 2015-2016. We found no differences in total Hg (THg) measured in red muscle between the two regions and no seasonal differences, likely due to the age of the fish and slow elimination rates of Hg. Our THg concentrations are comparable to those of other studies in the Pacific (0.20-9.60 mg/kg wet wt), but a subset of individuals exhibited the highest Hg concentrations yet reported in yellowfin tuna. Mercury isotope values differed between Δ199 Hg and δ202Hg in both regions (Δ199 Hg = 2.86 ± 0.04‰ vs. Δ199 Hg = 2.33 ± 0.07‰), likely related to shifting food webs and differing photochemical processing of Hg prior to entry into the food web. There were significantly lower values of both δ15 N and δ13 C in tuna from Galápagos Marine Reserve (δ15 N: 8.5-14.2‰, δ13 C: -18.5 to -16.1‰) compared with those from the Ecuadorian mainland coast (δ15 N: 8.3-14.4‰, δ13 C: -19.4 to -11.9‰), of which δ13 C values suggest spatially constrained movements of tuna. Results from the pooled analysis, without considering region, indicated that variations in δ13 C and δ15 N values tracked changes of Hg stable isotopes. Our data indicate that the individual tuna we used were resident fish of each region and were heavily influenced by upwellings related to the eastern Pacific oxygen minimum zone and the Humboldt Current System. The isotopes C, N, and Hg reflect foraging behavior mainly on epipelagic prey in shallow waters and that food web shifts drive Hg variations between these populations of tuna. Environ Toxicol Chem 2022;41:2732-2744. © 2022 SETAC.

Rapid adaptive radiation of Darwin's finches depends on ancestral genetic modules.

Recent adaptive radiations are models for investigating mechanisms contributing to the evolution of biodiversity. An unresolved question is the relative importance of new mutations, ancestral variants, and introgressive hybridization for phenotypic evolution and speciation. Here, we address this issue using Darwin's finches and investigate the genomic architecture underlying their phenotypic diversity. Admixture mapping for beak and body size in the small, medium, and large ground finches revealed 28 loci showing strong genetic differentiation. These loci represent ancestral haplotype blocks with origins predating speciation events during the Darwin's finch radiation. Genes expressed in the developing beak are overrepresented in these genomic regions. Ancestral haplotypes constitute genetic modules for selection and act as key determinants of the unusual phenotypic diversity of Darwin's finches. Such ancestral haplotype blocks can be critical for how species adapt to environmental variability and change.

HEALTH STATUS OF NAZCA BOOBIES (SULA GRANTI) ON DAPHNE MAJOR ISLAND IN THE GALÁPAGOS DETERMINED BY HEMATOLOGY, BIOCHEMISTRY, AND PHYSICAL EXAMINATION.

Island species are particularly vulnerable to environmental disturbances and introduced pathogens. Conducting health assessments of wild populations in the Galápagos improves the ability of wildlife managers and veterinarians to detect deteriorations in health status. Seabirds in particular are useful species to monitor due to their colonial breeding and wide migration range. Nazca boobies (Sula granti) in a breeding colony at Daphne Major (n = 30) were given physical examinations, and blood samples were collected for hematology and biochemistry using an iSTAT Portable Clinical Analyzer. Female boobies had longer wing length than males, as well as lower blood urea nitrogen, creatinine, and white blood cell counts. This could be attributed to sexual dimorphism or differences in foraging and mating strategies between the sexes. The time between capture and blood collection had a significant inverse relationship on plasma sodium, potassium, hemoglobin, anion gaps, and lymphocyte counts, suggesting that blood sampling in Nazca boobies should be done in less than 5 m to avoid the impacts of stress on hematological parameters. This is the first health assessment on the breeding colony of Nazca boobies at Daphne Major, and the results can inform future monitoring in this species as well as other sulids.

HEALTH STATUS AND BASELINE HEMATOLOGY, BIOCHEMISTRY, AND BLOOD GAS VALUES OF GALAPAGOS SHEARWATERS (PUFFINUS SUBALARIS).

The Galápagos shearwater, Puffinus subalaris, is a seabird endemic to the Galápagos archipelago. Hematology, blood chemistry, and general health parameters have not been published for this species. Analyses were run on blood samples drawn from 20 clinically healthy Galápagos shearwaters captured by hand at their nests at Islote Pitt on San Cristóbal Island in July 2016. A portable blood analyzer (iSTAT) was used to obtain near immediate field results for pH, pO2, pCO2, TCO2, HCO3 -, hematocrit, hemoglobin, sodium, potassium, chloride, ionized calcium, creatinine, urea nitrogen, anion gap, and glucose. Blood lactate was measured using a portable Lactate Plus analyzer. The reported results provide baseline data that can be used for comparisons among populations and in detecting changes in health status among Galápagos shearwaters.

Baseline haematology, biochemistry, blood gas values and health status of the Galapagos swallow-tailed gull (Creagrus furcatus).

The swallow-tailed gull, Creagrus furcatus, is a seabird endemic to the Galápagos archipelago. In general health, blood chemistry and haematology, parameters have not been published for this species. Blood analyses were run on samples drawn from 58 clinically healthy swallow-tailed gulls captured at Islote Pitt on San Cristóbal Island in July 2016 (28) and South Plaza Island in June 2017 (30). A point of care blood analyzer (iSTAT) was used in the field to obtain results for HCO3 -, pH, pCO2, pO2, TCO2, anion gap, chloride, creatinine, glucose, haematocrit, haemoglobin, ionized calcium, potassium, sodium and urea nitrogen. A portable Lactate Plus™ analyzer was used to measure lactate. The baseline data reported is valuable for comparisons amongst different populations in the archipelago and to detect changes in health status of Galápagos swallow-tailed gulls.

Health assessment of Conolophus subcristatus, Conolophus pallidus, and C. subcristatus X Amblyrhynchus cristatus hybrid (Galápagos land iguanas).

The land iguanas, Conolophus pallidus and Conolophus subcristatu are large and charismatic lizards endemic to the Galápagos archipelago, but little information exists on their normal health parameters. The former is restricted to Santa Fe island, while C. subcristatus inhabits the islands of the central and western region of the archipelago. Both species are classified as vulnerable by the IUCN Red List of Threatened Species. As part of a population health assessment authorized by the Galápagos National Park, wild adult iguanas from three islands (North Seymour, South Plazas, and Santa Fe) were captured in July 2018. Data from a single C. subcristatus X Amblyrhynchus cristatus hybrid captured on South Plazas is also included. We analyzed blood samples drawn from 52 healthy wild adult land iguanas captured on three islands. An iSTAT portable blood analyzer was used to obtain values for pH, lactate, pO2, pCO2, HCO3-, sO2%, hematocrit, packed cell volume (PCV), hemoglobin Na, K, iCa, and glucose. Standard laboratory hematology techniques were employed for PCV determination; resulting values were also compared to the hematocrit values generated by the iSTAT. Body temperature, heart rate, respiratory rate, and body measurements were also recorded and compared to previously published data for the marine iguana (Amblyrhynchus cristatus), which shares a common ancestor with the land iguana. The data reported here provide preliminary baseline values that may be useful in comparisons between captive and wild populations, between wild populations, and in detecting changes in health status among Galápagos land iguanas affected by anthropogenic threats, climate change, or natural disturbances.

Methods of body temperature assessment in Conolophus subcristatus, Conolophus pallidus (Galápagos land iguanas), and Amblyrhynchus cristatus X C. subcristatus hybrid.

Since cardiovascular, respiratory, and metabolic systems of reptiles are affected by temperature, accurate measurements are of great importance in both captive husbandry and research. Ectothermic animals generally have core body temperatures close to ambient temperature but can differ from the immediate environment if they are using sunlight to thermoregulate. Many zoological facilities and exotic pet caregivers have begun using infrared temperature guns to assess ambient temperatures of reptile enclosures but there are currently few studies assessing the efficacy of these devices for measuring the body temperatures of reptiles. Conolophus subcristatus, Conolophus pallidus (Galápagos land iguanas), and Amblyrhynchus cristatus X C. subcristatus hybrid are robust land iguanas endemic to the Galápagos archipelago. By comparing the infrared body temperature measurements of land iguanas against virtual simultaneous collection of cloacal temperatures obtained using a thermocouple thermometer, we sought to assess the efficacy of this non-invasive method. We found that internal body temperature can be predicted with a high level of accuracy from three external body temperature sites, providing a good non-invasive method that avoids the capture of animals.

Haematology and biochemistry of the San Cristóbal Lava Lizard (Microlophus bivittatus).

The San Cristóbal lava lizard, Microlophus bivittatus, is one of nine species of lava lizards endemic to the Galápagos Islands of Ecuador. No information presently exists about baseline health parameters for any of these species. We analysed blood samples drawn from 47 lizards (25 males and 22 females) captured at two locations on San Cristóbal Island. A portable blood analyser (iSTAT) was used to obtain near-immediate field results for total CO2, lactate, sodium, potassium, ionized calcium, glucose and haemoglobin. Standard laboratory haematology techniques were employed for differential white blood cell counts and haematocrit determination. Body temperature, heart rate and body measurements were also recorded. We found significant differences in haematocrit values between males and females. The values reported in this study provide baseline data that may be useful in detecting changes in health status among lava lizards affected by natural disturbances or anthropogenic threats. Our findings might also be helpful in future efforts to demonstrate associations between specific biochemical or haematological parameters and disease. Because there are several related species on different islands in the Galápagos archipelago, comparisons between populations and species will be of interest. Lay Summary:Haematology and biochemistry values of the San Cristóbal lava lizard Microlophus bivittatus, along with several other health parameters (morphometrics and temperature), are reported for the first time.

Health Status of Great Frigatebirds (Fregata minor) Determined by Haematology, Biochemistry, Blood Gases, and Physical Examination.

The great frigatebird, Fregata minor, is a widely distributed seabird native to the Galápagos archipelago. Haematology and blood chemistry parameters have been published for this species but not from the San Cristóbal and North Seymour great frigatebird breeding colonies. Analyses were run on blood samples drawn from 25 great frigatebirds captured by hand at their nests at Punta Pitt on San Cristóbal Island and 30 birds on North Seymour Island, Galápagos Islands. A portable blood analyser (iSTAT) was used to obtain near immediate field results for pH, pO2, pCO2, TCO2, HCO3- , haematocrit (Hct), haemoglobin (Hb), sodium (Na), potassium (K), chloride (Cl), ionized calcium (iCa), creatinine, urea nitrogen, anion gap and glucose. Blood lactate was measured using a portable Lactate Plus™ analyser. Average heart rate, respiratory rate, body weight, body temperature, biochemistry and haematology parameters were comparable to healthy individuals of other Fregatidae. The reported results provide baseline data that can be used for comparisons among populations and in detecting changes in health status among Galápagos great frigatebirds.

Impact of Telemedicine on Mortality, Length of Stay, and Cost Among Patients in Progressive Care Units: Experience From a Large Healthcare System.

OBJECTIVES: To determine whether Telemedicine intervention can affect hospital mortality, length of stay, and direct costs for progressive care unit patients. DESIGN: Retrospective observational. SETTING: Large healthcare system in Florida. PATIENTS: Adult patients admitted to progressive care unit (PCU) as their primary admission between December 2011 and August 2016 (n = 16,091). INTERVENTIONS: Progressive care unit patients with telemedicine intervention (telemedicine PCU [TPCU]; n = 8091) and without telemedicine control (nontelemedicine PCU [NTPCU]; n = 8000) were compared concurrently during study period. MEASUREMENTS AND MAIN RESULTS: Primary outcome was progressive care unit and hospital mortality. Secondary outcomes were hospital length of stay, progressive care unit length of stay, and mean direct costs. The mean age NTPCU and TPCU patients were 63.4 years (95% CI, 62.9-63.8 yr) and 71.1 years (95% CI, 70.7-71.4 yr), respectively. All Patient Refined-Diagnosis Related Group Disease Severity (p < 0.0001) and All Patient Refined-Diagnosis Related Group patient Risk of Mortality (p < 0.0001) scores were significantly higher among TPCU versus NTPCU. After adjusting for age, sex, race, disease severity, risk of mortality, hospital entity, and organ systems, TPCU survival benefit was 20%. Mean progressive care unit length of stay was lower among TPCU compared with NTPCU (2.6 vs 3.2 d; p < 0.0001). Postprogressive care unit hospital length of stay was longer for TPCU patients, compared with NTPCU (7.3 vs 6.8 d; p < 0.0001). The overall mean direct cost was higher for TPCU ($13,180), compared with NTPCU ($12,301; p < 0.0001). CONCLUSIONS: Although there are many studies about the effects of telemedicine in ICU, currently there are no studies on the effects of telemedicine in progressive care unit settings. Our study showed that TPCU intervention significantly decreased mortality in progressive care unit and hospital and progressive care unit length of stay despite the fact patients in TPCU were older and had higher disease severity, and risk of mortality. Increased postprogressive care unit hospital length of stay and total mean direct costs inclusive of telemedicine costs coincided with improved survival rates. Telemedicine intervention decreased overall mortality and length of stay within progressive care units without substantial cost incurrences.

Maximum likelihood estimation for stochastic volatility in mean models with heavy-tailed distributions.

In this article, we introduce a likelihood-based estimation method for the stochastic volatility in mean (SVM) model with scale mixtures of normal (SMN) distributions (Abanto-Valle et al., 2012). Our estimation method is based on the fact that the powerful hidden Markov model (HMM) machinery can be applied in order to evaluate an arbitrarily accurate approximation of the likelihood of an SVM model with SMN distributions. The method is based on the proposal of Langrock et al. (2012) and makes explicit the useful link between HMMs and SVM models with SMN distributions. Likelihood-based estimation of the parameters of stochastic volatility models in general, and SVM models with SMN distributions in particular, is usually regarded as challenging as the likelihood is a high-dimensional multiple integral. However, the HMM approximation, which is very easy to implement, makes numerical maximum of the likelihood feasible and leads to simple formulae for forecast distributions, for computing appropriately defined residuals, and for decoding, i.e., estimating the volatility of the process.

Bayesian analysis of stochastic volatility-in-mean model with leverage and asymmetrically heavy-tailed error using generalized hyperbolic skew Student's t-distribution.

A stochastic volatility-in-mean model with correlated errors using the generalized hyperbolic skew Student-t (GHST) distribution provides a robust alternative to the parameter estimation for daily stock returns in the absence of normality. An efficient Markov chain Monte Carlo (MCMC) sampling algorithm is developed for parameter estimation. The deviance information, the Bayesian predictive information and the log-predictive score criterion are used to assess the fit of the proposed model. The proposed method is applied to an analysis of the daily stock return data from the Standard & Poor's 500 index (S&P 500). The empirical results reveal that the stochastic volatility-in-mean model with correlated errors and GH-ST distribution leads to a significant improvement in the goodness-of-fit for the S&P 500 index returns dataset over the usual normal model.

HEALTH STATUS OF RED-FOOTED BOOBIES ( SULA SULA) DETERMINED BY HEMATOLOGY, BIOCHEMISTRY, BLOOD GASES, AND PHYSICAL EXAMINATION.

The red-footed booby ( Sula sula) is a widely distributed sulid native to the Galápagos archipelago. Hematology and blood chemistry parameters have been published for this species, but not from the San Cristóbal rookery. Analyses were run on blood samples drawn from 31 manually restrained red-footed boobies that were captured by hand from their nests at Punta Pitt on San Cristóbal Island. A portable blood analyzer (iSTAT) was used to obtain near immediate field results for pH, partial pressure of oxygen, partial pressure of carbon dioxide, bicarbonate, hematocrit, hemoglobin, sodium, potassium, ionized calcium, and glucose. Blood lactate was measured using a portable Lactate Plus™ analyzer. Average heart rate, respiratory rate, body weight, body temperature, and biochemistry and hematology parameters were comparable to those of healthy individuals of other sulids. The reported results provide baseline data that can be used for comparisons among populations and in detecting changes in health status among Galápagos red-footed boobies.

Quantile regression for censored mixed-effects models with applications to HIV studies.

HIV RNA viral load measures are often subjected to some upper and lower detection limits depending on the quantification assays. Hence, the responses are either left or right censored. Linear/nonlinear mixed-effects models, with slight modifications to accommodate censoring, are routinely used to analyze this type of data. Usually, the inference procedures are based on normality (or elliptical distribution) assumptions for the random terms. However, those analyses might not provide robust inference when the distribution assumptions are questionable. In this paper, we discuss a fully Bayesian quantile regression inference using Markov Chain Monte Carlo (MCMC) methods for longitudinal data models with random effects and censored responses. Compared to the conventional mean regression approach, quantile regression can characterize the entire conditional distribution of the outcome variable, and is more robust to outliers and misspecification of the error distribution. Under the assumption that the error term follows an asymmetric Laplace distribution, we develop a hierarchical Bayesian model and obtain the posterior distribution of unknown parameters at the pth level, with the median regression (p = 0.5) as a special case. The proposed procedures are illustrated with two HIV AIDS studies on viral loads that were initially analyzed using the typical normal (censored) mean regression mixed-effects models, as well as a simulation study.

Complicaciones de la capsulotomía posterior por láser de Nd-Yag en el Centro Oftalmológico "Enrique Cabrera" de La Habana / Complications of posterior capsulotomy due to Nd-Yag laser in "Enrique Cabrera" Ophthalmological Center from Havana

Introducción: La opacidad capsular posterior es la complicación más frecuente de la cirugía de catarata y, aunque la capsulotomía con láser de Nd-Yag es un procedimiento muy efectivo para solucionarla, no está exenta de complicaciones.Objetivo: Describir las complicaciones en pacientes expuestos a capsulotomía con láser de Nd-Yag.Métodos: Se realizó un estudio descriptivo y prospectivo de 104 pacientes con opacidad capsular posterior, atendidos en el Centro Oftalmológico "Enrique Cabrera" de la Habana, durante el 2010. Se analizaron las variables frecuencia y tipo de complicaciones, edad, sexo, antecedentes patológicos personales oculares y sistémicos, clasificación de la opacidad capsular, energía utilizada, así como agudeza visual antes y después del tratamiento.Resultados: En la casuística predominaron el aumento de la presión intraocular y el edema macular quístico como las complicaciones más comunes, los pacientes de 56-75 años, el sexo femenino, así como la opacidad capsular fibrótica y la capsulotomía con más de 8,0 MJ.Conclusiones: Más de la mitad de los afectados presentaron complicaciones de carácter transitorio y reversible, las cuales no estuvieron relacionadas con la cantidad de energía empleada; la mejoría visual después del proceder fue notable.

Introduction: The posterior capsular opacity is the most frequent complication in the cataract surgery and, although capsulotomy with Nd-Yag laser is a very effective procedure to solve it, it is not free of complications. Objective: To describe the complications in patients exposed to capsulotomy with Nd-Yag laser.Methods: A descriptive and prospective study of 104 patients with posterior capsular opacity, assisted in "Enrique Cabrera" Ophthalmological Center from Havana, was carried out during the 2010. Variables of frequency and type of complication, age, sex, pathological ocular and systemic medical history, classification of the capsular opacity, energy used, as well as visual acuity before and after the treatment were analyzed.Results: The increase of the intraocular pressure and the cystic macular edema as the most common complications, the 56-75 year-old patients, female sex, as well as the capsular fibrotic opacity and the capsulotomy with more than 8,0 MJ prevailed in the case material.Conclusions: More than half of the patients presented complications of transitory and reversible type, which were not related to the quantity of energy used; the visual improvement after the procedure was remarkable.