Detection of macro-ecological patterns in South American hummingbirds is affected by spatial scale.

Scale is widely recognized as a fundamental conceptual problem in biology, but the question of whether species-richness patterns vary with scale is often ignored in macro-ecological analyses, despite the increasing application of such data in international conservation programmes. We tested for scaling effects in species-richness gradients with spatially scaled data for 241 species of South American hummingbirds (Trochilidae). Analyses revealed that scale matters above and beyond the effect of quadrat area. Species richness was positively correlated with latitude and topographical relief at ten different spatial scales spanning two orders of magnitude (ca. 12,300 to ca. 1,225,000 km2). Surprisingly, when the influence of topography was removed, the conditional variation in species richness explained by latitude fell precipitously to insignificance at coarser spatial scales. The perception of macro-ecological pattern thus depends directly upon the scale of analysis. Although our results suggest there is no single correct scale for macro-ecological analyses, the averaging effect of quadrat sampling at coarser geographical scales obscures the fine structure of species-richness gradients and localized richness peaks, decreasing the power of statistical tests to discriminate the causal agents of regional richness gradients. Ideally, the scale of analysis should be varied systematically to provide the optimal resolution of macro-ecological pattern.

Objective measurement of hot flushes associated with the premenstrual syndrome.

Because the majority of women with PMS complain of sweats and chills resembling menopausal flushes, we attempted to document the physiologic changes during these episodes. A 26-year-old nulliparous woman with PMS described the occurrence of hot flush-like episodes coincident with PMS symptoms. The patient completed prospective self-rating scales for two consecutive cycles to establish the pattern and severity of PMS. On day 26 of the first cycle when PMS symptom scores were elevated, continuous monitoring of skin resistance and finger temperature and frequent blood sampling for LH were performed for 8 hours. The patient experienced five flush episodes, each of which was associated with a drop in skin resistance of up to 4000 ohms and was coincident with an LH pulse. Three of the flushes were associated with a rise in finger temperature of up to 10 degrees C. These physiologic changes are identical to those seen during menopausal flushes and suggest that PMS may be associated with neuroendocrine events typical of E withdrawal.

In vitro fertilization: diurnal and seasonal variation in luteinizing hormone surge onset and pregnancy rates.

The authors studied 740 consecutive in vitro fertilization (IVF) cycles over a 3-year period to compare the results of cycles in which an endogenous luteinizing hormone (LH) surge occurred with cycles in which human chorionic gonadotropin (hCG) was administered for induction of follicular maturation. Clomiphene citrate (100 to 150 mg daily on cycle days 5 to 9) and human menopausal gonadotropin (hMG; 75 to 150 IU daily from cycle day 6) were used for stimulation. Embryo transfer (ET) occurred in 164 (81.2%) of the LH surge cycles and 452 (84%; P = not significant [NS] of the hCG cycles. The first urinary rise in LH was detected in the 6 or 9 A.M. collections in 78 (47.3%) of the LH surge cycles, a greater number (P less than 0.01) than expected if LH surge onset was random. A total of 107 pregnancies was achieved, for an overall pregnancy rate of 17.4% per ET. The pregnancy rate in the hCG-stimulated cycles was 13.9% per ET (63/452) and, in spontaneous LH surge cycles, was 28.8% (44/166; P less than 0.001). The spontaneous abortion rate was 9.1% in LH surge cycles, compared with 25.4% in hCG-triggered cycles (P less than 0.001). The result was a 2.4 times increase in live births for LH surge cycles compared with cycles in which hCG was administered. In this program, occurrence of an LH surge is a favorable event, associated with higher pregnancy and live birth rates than hCG-stimulated cycles, and usually occurring in the early morning, allowing oocyte retrieval during normal working hours.

Neonatal salvage by week's gestation in pregnancies complicated by HELLP syndrome.

OBJECTIVE: For clinical management and counseling purposes, we determined the neonatal salvage by weeks' gestation and birth weight of pregnancies complicated by HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets). METHODS: All patients who delivered with a diagnosis of HELLP syndrome between January 1, 1980 and December 31, 1991 at a single tertiary care medical center were evaluated for neonatal outcome and survival. The syndrome was diagnosed in the presence of severe preeclampsia/eclampsia accompanied by laboratory evidence of hemolysis, hepatic dysfunction, and thrombocytopenia. RESULTS: During the study interval, 58,670 live-born deliveries occurred, of which 527 (0.11%) had HELLP syndrome. In this population, 143 patients delivered fetuses at less than 30 weeks' gestational age. Based upon gestational age intervals, neonatal salvage was 0% at 23 weeks in 13 deliveries, 17% (intact salvage 8.5%) at 24 weeks, 31% (intact salvage 15%) at 25 weeks, 75% (intact salvage 65%) at 26 weeks, 80% (intact salvage 70%) at 27 weeks, and 83% at 28 and 29 weeks (intact salvage 70 and 76%). Based on birth weight intervals, neonatal salvage was 0% at less than 600 g, 34% at 600-700 g (intact salvage 17%), 69% at 700-800 g (intact salvage 53%), and 84% or more at greater than 800 g. These pregnancy outcomes are similar to those in this institution in patients without HELLP syndrome. Disease severity was distributed evenly among the 143 patients at less than 30 weeks' gestation. Apart from gestational age, there was no significant relation between the severity of the HELLP disease process and ultimate neonatal salvage. CONCLUSIONS: Intact neonatal salvage in pregnancies complicated by HELLP syndrome is poor at weights less than 700 g and gestation of 25 weeks or less, but is more optimistic in pregnancies of greater than 700 g and 26 weeks' gestation or later. Aggressive efforts to enhance perinatal outcome, by operative delivery if indicated for fetal compromise, appear especially appropriate in gestations of greater than 700 g and 26 weeks' gestation or later, provided that adequate intensive care nursery facilities and neonatal expertise are available.

Health practices, attitudes, and beliefs of vegetarians and nonvegetarians.

Health practices, attitudes, and beliefs were studied in 150 vegetarians and 150 nonvegetarians matched for age and sex. A questionnaire was administered that included a medical history and questions concerning use of medications, recreational drugs, nutrition supplements, and alcohol; smoking habits; exercise; and relaxation activities. The questionnaire also included Likert scales on which the subjects rated themselves according to their knowledge and practice of nutrition and diet and their agreement or disagreement with statements concerning health. Vegetarians believed in visiting a physician when they were ill but were more willing to try alternative or unusual therapies and/or preventive treatments. Substances that are potentially harmful to the body, such as alcohol, tobacco, or prescription drugs, were used less frequently by vegetarians. Conversely, greater use was seen of substances that are thought to improve health. The area of greatest difference between the groups was in their attitudes and beliefs concerning health. Although the vegetarians believed that they as a group were healthier than nonvegetarians, the lack of differences in self-ratings of health and incidence of health problems suggest that that perception may not be true.

The use of isotope tracers for identifying populations of migratory birds.

To determine whether stable isotopes can be used for identifying the geographic origins of migratory bird populations, we examined the isotopic composition of hydrogen (deuterium, δD), carbon (δ13C), and strontium (δ87Sr) in tissues of a migratory passerine, the black-throated blue warbler (Dendroica caerulescens), throughout its breeding range in eastern North America. δD and δ13C values in feathers, which are grown in the breeding area, varied systematically along a latitudinal gradient, being highest in samples from the southern end of the species' breeding range in Georgia and lowest in southern Canada. In addition, δD decreased from east to west across the northern part of the breeding range, from New Brunswick to Michigan. δ87Sr ratios were highest in the Appalachian Mountains, and decreased towards the west. These patterns are consistent with geographical variation in the isotopic composition of the natural environment, i.e., with that of precipitation, plants, and soils for δD, δ13C, and δ87Sr, respectively. Preliminary analyses of the δD and δ13C composition of feathers collected from warblers in their Caribbean winter grounds indicate that these individuals were mostly from northern breeding populations. Furthermore, variances in isotope ratios in samples from local areas in winter tended to be larger than those in summer, suggesting that individuals from different breeding localities may mix in winter habitats. These isotope markers, therefore, have the potential for locating the breeding origins of migratory species on their winter areas, for quantifying the degree of mixing of breeding populations on migratory and wintering sites, and for documenting other aspects of the population structure migratory animals - information needed for studies of year-round ecology of these species as well as for their conservation. Combining information from several stable isotopes will help to increase the resolution for determining the geographic origins of individuals in such highly vagile populations.

Relationship of cranial midline shift to outcome of very-low-birth-weight infants with periventricular hemorrhagic infarction.

The purpose of this study was to determine the relationship of a cranial midline shift accompanying periventricular hemorrhagic infarction to subsequent handicap in very-low-birth-weight infants. A study group of 44 infants with intraventricular hemorrhage and an associated periventricular hemorrhagic infarction was retrospectively selected from 1,080 very-low-birth-weight infants evaluated by cranial sonography. A cranial midline shift is defined sonographically as displacement of the septum pellucidum (or cavum septi pellucidi) more than 3 mm from the spatial midline. The midline is measured as half the distance between the right and left inner tables on an anterior coronal view. Other sonographic data recorded were the size of the lateral ventricle, the intracranial hemisphere, and the periventricular hemorrhagic infarction. Also noted was the appearance of the area of infarction at the time of initial detection of a midline shift. After discharge, the infants were periodically evaluated for major handicap in vision, hearing, cognition, and motor activity. A midline shift was identified in 29 (66%) of 44 infants with periventricular hemorrhagic infarction. Seven (24%) of the 29 infants with midline shift and 3 (20%) of the 15 infants without a midline shift died. In all of the 22 surviving infants with a midline shift and in 3 (25%) of 12 survivors without a midline shift, a handicap developed (p < 0.01). As a predictor of handicap, midline shift showed a sensitivity of 88% and a specificity of 100%. Predictability was not improved by combining midline shift with the size of the parenchymal infarct.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term outcome of infants at the margin of viability.

The outcome of babies at extremely short gestational age (22 to 26 weeks) effects our clinical decisions regarding their care. We looked at survival and presence of disability at 25 +/- 11 months of age in 246 of these infants born at our hospital between 1992 and 1996 who were average weight for gestational age. Babies were evaluated in our follow up clinic by a pediatrician, and a physical therapist for cerebral palsy, blindness and deafness, and by a psychologist with the Bayley II. Chances for survival without disability exceeded 50% of live born infants at 25 weeks gestation or a birth weight of 700 to 800 grams. Chances for survival exceeded 50% of live born infants at 24 weeks gestation or a birth weight of 600 to 700 grams. Chances for intact survival reached 50% of survivors at 23 weeks gestation or a birth weight of 400 to 500 grams.

Improving access to pediatric health care in Mississippi.

Working under the Mississippi Postneonatal Death Impact Project, the Mississippi Chapter of the American Academy of Pediatrics, in conjunction with the State Department of Health, helped improve access to pediatric health care in Mississippi. This was accomplished by developing a statewide telephone information and referral service (telephone case management), enlisting primary care physicians to treat a limited number of children without specific compensation and staging a public awareness campaign. System barriers encountered were identified and interagency coordination and cooperation suggested. This effort could be easily replicated and expanded.

Bergmann's rule near the equator: latitudinal clines in body size of an Andean passerine bird.

Critical correlative support for Bergmann's ecogeographic rule is provided by symmetrical patterns of size variation in Diglossa carbonaria, a tropical passerine bird whose geographic range in the Andes Mountains of South America straddles the equator. Body size is positively correlated with latitude both north and south of the equator. Moreover, parapatric taxa that exhibit either partial (north-western Bolivia) or complete (northern Peru) reproductive isolation converge in body size. Relative uniformity in the length of the highly modified flower-piercing bill among populations of D. carbonaria that differ significantly in body size suggests that character displacement or interspecific competition is not responsible for these patterns. These findings support the hypothesis that climate, particularly temperature seasonality, is an important environmental determinant of geographic size variation in homeotherms. In addition they demonstrate that clinal variation correlated with subtle climatic gradients can occur in tropical environments.

Assembly of avian mixed-species flocks in Amazonia.

Diamond's "assembly rules" model posits that competitive interactions among species govern the composition of avifaunas. Although originally applied to islands in archipelagoes, this controversial set of hypotheses is difficult to test because islands differ in habitat and resource availability, colonization history, and stochastic effects. Permanent mixed-species flocks of Amazonian birds are a model system for testing the assembly rules hypothesis because flocks occur in relatively homogeneous tracts of rain forest and because resident species are potentially interactive from minute to minute. To analyze cooccurrence patterns of species in flocks, we used null models that incorporate realistic autecological colonization parameters. Potentially competing pairs of congeneric species with similar ecologies cooccur in flocks less often than expected by chance, resulting in perfect checkerboard distributions. Interactions among more distantly related species, however, appear to have little effect on the assembly of mixed-species flocks. Checkerboard distributions enhance local species diversity within habitats by generating different combinations of species in different flocks. This process may have contributed to the immense species richness of the Amazonian avifauna.

Multiscale assessment of patterns of avian species richness.

The search for a common cause of species richness gradients has spawned more than 100 explanatory hypotheses in just the past two decades. Despite recent conceptual advances, further refinement of the most plausible models has been stifled by the difficulty of compiling high-resolution databases at continental scales. We used a database of the geographic ranges of 2,869 species of birds breeding in South America (nearly a third of the world's living avian species) to explore the influence of climate, quadrat area, ecosystem diversity, and topography on species richness gradients at 10 spatial scales (quadrat area, approximately 12,300 to approximately 1,225,000 km(2)). Topography, precipitation, topography x latitude, ecosystem diversity, and cloud cover emerged as the most important predictors of regional variability of species richness in regression models incorporating 16 independent variables, although ranking of variables depended on spatial scale. Direct measures of ambient energy such as mean and maximum temperature were of ancillary importance. Species richness values for 1 degrees x 1 degrees latitude-longitude quadrats in the Andes (peaking at 845 species) were approximately 30-250% greater than those recorded at equivalent latitudes in the central Amazon basin. These findings reflect the extraordinary abundance of species associated with humid montane regions at equatorial latitudes and the importance of orography in avian speciation. In a broader context, our data reinforce the hypothesis that terrestrial species richness from the equator to the poles is ultimately governed by a synergism between climate and coarse-scale topographic heterogeneity.

Nonimmune hydrops fetalis: antenatal diagnosis and management.

An 8-year (1975-1982) study of 26 cases of nonimmune fetal hydrops revealed the main causes to be: anomalies (11/26), tachyarrhythmias (4/26), and twin-to-twin transfusion (4/26). The perinatal mortality was 19/26 (76%). Based on this series, and a review of the literature, a plan for the antenatal diagnosis and management of these cases is outlined.

Tachycardia as a sign of early onset neonatal sepsis.

A prospective study in two parts was designed to assess tachycardia in neonates (less than 72 hours of age) and its role as an early indicator of neonatal sepsis. In Part I of the study we determined the incidence of tachycardia among all inborn neonates in 1 year, and in Part II we assessed the presence of tachycardia in inborn and outborn infants evaluated for sepsis. Twenty-one infants were tachycardic among 4530 live births (incidence, 4.64/1000). Ten tachycardic infants were septic. Of 82 infants who were evaluated for sepsis, 13 had proved sepsis, 12 of whom had tachycardia as one of their presenting symptoms. Of the remaining nonseptic infants 6 of 69 had tachycardia. There was a significant difference in the two groups (P less than 0.001). The results demonstrate that tachycardia is an important sign of neonatal sepsis.

Neonatal fungemia and amphotericin B.

Disseminated candidemia is a common nosocomial infection in the neonatal intensive care unit, though only a few studies have reported the outcome of amphotericin B therapy in neonatal candidiasis. Our treatment regimen consisted of an initial daily amphotericin B dose of 0.5 mg/kg. (For infants weighing > 1 kg, the second dose was increased to 1 mg/kg.) At 3 to 5 days, if the blood culture was negative, amphotericin B therapy was changed to every other day and continued for a total of 10 doses. Records of 36 patients given this regimen were reviewed for signs of toxicity or treatment failure. The mean birth weight was 988 +/- 510 g, and the gestational age was 28 +/- 3.9 weeks. The patients were ventilated for 13 +/- 15 days and had central lines for 6.7 +/- 9.3 days before development of candidemia. The mean age at onset of candidemia was 29.1 +/- 19.8 days. The interval from culture to treatment was 2.9 days. Six of 36 patients died, 2 of candidal meningitis and 4 of complications unrelated to candidal infection. Thirteen (36%) of the patients had candidal pustules during the course of their disease; 1 had osteomyelitis. There was no evidence of toxicity from this drug regimen and no apparent treatment failures. There were no changes in BUN and creatinine before or during therapy and no change in total urinary output. Blood cultures became sterile except in one patient who died on the first day of therapy. Most of the patients in this study had candidemia in the absence of a central indwelling catheter. Further prospective pharmacokinetic and therapeutic studies are warranted for this regimen of amphotericin B, which carries a low risk for toxicity.

Torulopsis glabrata in the neonate: an emerging fungal pathogen.

Fungi are becoming increasingly common nosocomial pathogens in the neonatal intensive care patient. The fungus Torulopsis glabrata, a common skin inhabitant, is a potential pathogen in the high-risk neonate. In this report we have reviewed the cases of two infants in which systemic T glabrata infection was diagnosed. One patient survived without apparent sequelae; the other died before diagnosis and initiation of therapy. Five other cases of systemic infection by T glabrata in neonates have been reported previously, with only one survivor. Early recognition and treatment of this nearly uniformly fatal infection is imperative.