Ecomorphology of Neotropical Electric Fishes: An Integrative Approach to Testing the Relationships between Form, Function, and Trophic Ecology.

The relationship between form and function is thought to play an integral role in structuring broad-scale patterns of morphological evolution and resource utilization. In ecomorphological studies, mechanical performance is widely understood to constrain the evolution of form and function. However, the relationship between form, function, and resource utilization is less clear. Additionally, seasonal fluctuations in resource availability may further complicate patterns of resource use. How organisms cope with these complexities, and the effect of these factors on broadscale patterns of morphological evolution is also poorly understood. Here we use three-dimensional geometric morphometrics, biomechanics, stable isotope analysis, and gut-content analysis to study trophic evolution in a clade of riverine-adapted electric fishes from a region with high seasonal variability; the Amazon River. We find significant and phylogenetically structured relationships among measures of trophic ecology and skull shape. We also recover a significant relationship between the mechanical advantage of the mandible and trophic position, where species feeding at higher trophic levels have narrower jaws with lower mechanical advantages, and species feeding at lower trophic levels have deeper jaws with higher mechanical advantages. Our results indicate that selection is driving the evolution of mandible shape and performance toward specialization on different trophic ecologies.

Ecomorfologia de Peixes Elétricos Neotropicais: Uma Abordagem Integrativa para Testar as Relações Entre Forma, Função, e Ecologia Trófica Acredita-se que a relação entre forma e função desempenhe um papel integral na estruturação de padrões de larga-escala de evolução morfológica e utilização de recursos. Em estudos ecomorfológicos, se é amplamente atribuído ao desempenho mecânico a restrição da evolução da forma e da função. Em estudos de sistemas complexos, como mandíbulas de peixes, a ideia de que a morfologia está relacionada ao desempenho é frequentemente estabelecida, mas sua relação com a utilização de recursos é menos clara. Aqui, nós usamos morfometria geométrica tridimensional, biomecânica, análise de isótopos estáveis e análise de conteúdo intestinal para estudar a evolução trófica em um clado de peixes elétricos adaptados a rios, da região da bacia Amazônica. Encontramos relações significativas e estruturadas filogeneticamente entre medidas de ecologia trófica e forma do crânio. Também recuperamos uma relação significativa entre a vantagem mecânica da mandíbula e posição trófica, onde as espécies que se alimentam em níveis tróficos superiores têm mandíbulas mais estreitas com menores vantagens mecânicas, e as espécies que se alimentam em níveis tróficos inferiores têm mandíbulas mais profundas com maiores vantagens mecânicas. Nossos resultados indicam que a seleção está conduzindo a evolução da forma e desempenho da mandíbula para a especialização em diferentes ecologias tróficas. Translated to Portuguese by J.P. Fontenelle (jp.fontenelle@mail.utoronto.ca).

Effect of relative humidity on preeclampsia.

PURPOSE OF INVESTIGATION: The authors aimed to determine the relationship between meteorological variables and hypertension in pregnancy by using data from a national weather database. MATERIALS AND METHODS: For this population-based observational study, the database of the Korea National Health Insurance (KNHI) Claims of the Health Insurance Review and Assessment Service (HIRA) and Korea Meteorological Administration was used. The 48,275 women with preeclampsia among 2,495,383 women who gave birth were included. Monthly meteorological factors and preeclampsia prevalence for five years were statistically analyzed. RESULTS: Among temperature, relative humidity, sunlight duration, and rainfall, only relative humidity had a significant inverse correlation with the preeclampsia prevalence (p < 0.001). The other meteorological factors were not associated with preeclampsia. CONCLUSION: Relative humidity may be a significant factor for of the development of preeclampsia. Further monitoring of weather parameters during the entire pregnancy period may be the best method for verifying the present results in the development of preeclampsia.

Mutagenicity studies of methyl-tert-butylether using the Ames tester strain TA102.

Methyl-tert-butylether (MTBE) is an oxygenate widely used in the United States as a motor vehicle fuel additive to reduce emissions and as an octane booster [National Research Council, Toxicological and Performance Aspects of Oxygenated Motor Vehicle Fules, National Academy Press, Washington, DC, 1996]. But it is the potential for MTBE to enter drinking water supplies that has become an area of public concern. MTBE has been shown to induce liver and kidney tumors in rodents but the biochemical process leading to carcinogenesis is unknown. MTBE was previously shown to be non-mutagenic in the standard Ames plate incorporation test with tester strains that detect frame shift (TA98) and point mutations (TA100) and in a suspension assay using TA104, a strain that detects oxidative damage, suggesting a non-genotoxic mechanism accounts for its carcinogenic potential. These strains are deficient in excision repair due to deletion of the uvrB gene. We hypothesized that the carcinogenic activity of MTBE may be dependent upon a functional excision repair system that attempts to remove alkyl adducts and/or oxidative base damage caused by direct interaction of MTBE with DNA or by its metabolites, formaldehyde and tert-butyl alcohol (TBA), established carcinogens that are mutagenic in some Ames strains. To test our hypothesis, the genotoxicity of MTBE-induced DNA alterations was assayed using the standard Ames test with TA102, a strain similar to TA104 in the damage it detects but uvrB + and, therefore, excision repair proficient. The assay was performed (1) with and without Aroclor-induced rat S-9, (2) with and without the addition of formaldehyde dehydrogenase (FDH), and (3) with human S-9 homogenate. MTBE was weakly mutagenic when tested directly and moderately mutagenic with S-9 activation producing between 80 and 200 TA102 revertants/mg of compound. Mutagenicity was inhibited 25%-30% by FDH. TA102 revertants were also induced by TBA and by MTBE when human S-9 was substituted for rat S-9. We conclude that MTBE and its metabolites induce a mutagenic pathway involving oxidation of DNA bases and an intact repair system. These data are significant in view of the controversy surrounding public safety and the environmental release of MTBE and similar fuel additives.

The argon "contact" laser scalpel: technical considerations.

The authors describe the use of a new contact argon laser scalpel designed specifically for hand-controlled cutting and hemostasis. This instrument delivers energy precisely to targeted tissue and produces minimal damage to adjacent healthy structures. Potential clinical applications are discussed.

The argon contact laser scalpel: a study of its effect on atherosclerosis.

A new argon laser scalpel (ALS) that delivers radiation to tissue by direct contact was used to perform endarterectomies on atherosclerotic rabbit aortas in vivo. The resultant effects were compared to those induced by CO2 laser (CO2) and conventional surgical endarterectomy (END) to determine whether this instrument might be useful in the treatment of occlusive cerebrovascular disease. Light microscopy of the treated aortic segments revealed significantly more atheroma removed and less damage to the underlying media in the ALS segments compared to the CO2 segments. Electron microscopy showed that the ALS surface and distal intima-media interface were smoother and more even than those of the CO2 or END groups. Prostacyclin synthesis, as measured by 6-keto-prostaglandin F1a levels, was significantly reduced in the ALS compared to the END and control segments. These results indicate that the ALS is superior to CO2 in performing open laser endarterectomies, but such treatment places the atherosclerotic blood vessel at greater risk for thrombotic complications during the early postoperative period that does surgical endarterectomy. It is conceivable that a contact laser may be useful in the smooth welding of the distal edge of an atheroma (i.e., during carotid endarterectomy) and for the transcatheter ablation of surgically inaccessible obstructions of the cerebral circulation.

Age-related rise in parathyroid hormone in man: the use of intact and midmolecule antisera to distinguish hormone secretion from retention.

Circulating levels of parathyroid hormone (PTH) rise with age in normal men and women. To resolve the basis for this observation we measured iPTH in 137 normal men and women, age 23 to 85 years, using two antisera which responded to different portions of the PTH molecule. A midmolecule assay (Mid-PTH) employed antiserum NG-5, which recognizes mid- and carboxy-terminal portions of hPTH, whereas antiserum CK-67, which recognizes determinants in the 1-34 hPTH sequence, was used to measure intact PTH (NH2-PTH). Two-hour fasting urine was collected for measurement of creatinine clearance and excretion indices of phosphorus and cyclic AMP. Serum was analyzed for 25-hydroxyvitamin D (25-OHD) in addition to iPTH. Mid-PTH rose significantly with age in the 72 women (r = 0.38, p less than 0.001) and in the 65 men (r = 0.40, p less than 0.001). NH2-PTH rose with age in women (r = 0.23, p less than 0.05), but a change in men was not significant (r = 0.19, n.s.). Cyclic AMP excretion rose significantly with age in both women (r = 0.42) and men (r = 0.41), whereas phosphorus excretion rose significantly in women only (r = 0.32, p less than 0.01). 25-OHD levels were 27.5 +/- 1.3 ng/ml for women and 26.1 +/- 1.2 ng/ml for men. No change in 25-OHD was observed with age in women, and a significant decrease in men was due entirely to extremely high values in three young subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Highly sensitive two-site immunoradiometric assay of parathyrin, and its clinical utility in evaluating patients with hypercalcemia.

We have developed a highly sensitive, two-site immunoradiometric assay (IRMA) for human parathyrin (PTH) that is specific for the intact, secreted, biologically active 84-amino-acid peptide. This assay has several technical advantages: it does not detect even high concentrations of inactive carboxyl-terminal fragments, results are available within 24 h, and the detection limit for intact hormone is low (1 ng/L). The assay readily measures concentrations of PTH in all healthy subjects and distinguishes these values from low or undetectable PTH values observed in clinical situations in which PTH secretion is expected to be suppressed. We found complete separation of results from 37 patients with surgically proven hyperparathyroidism and those from 23 patients with hypercalcemia associated with malignancy, the latter having PTH values at or below the lower limits of normal for this assay. The sensitivity, specificity, and rapid turnaround time of this two-site IRMA should advance the laboratory evaluation of patients with disorders of calcium metabolism.

Compression neuropathy of the radial nerve due to pentazocine-induced fibrous myopathy.

Fibrous myopathy is a common, well-known side effect of repeated pentazocine injection. However, compression neuropathy due to fibrotic muscle affected by pentazocine-induced myopathy has not previously been reported. In a 37-year-old woman with documented pentazocine-induced fibrous myopathy of triceps and deltoid muscles bilaterally and a three-week history of right wrist drop, electrodiagnostic examination showed a severe but partial lesion of the right radial nerve distal to the branches to the triceps, in addition to the fibrous myopathy. Surgery revealed the right radial nerve to be severely compressed by the densely fibrotic lateral head of the triceps. Decompression and neurolysis were performed with good subsequent recovery of function.