Leaf lifespan as a determinant of leaf structure and function among 23 amazonian tree species.

The relationships between resource availability, plant succession, and species' life history traits are often considered key to understanding variation among species and communities. Leaf lifespan is one trait important in this regard. We observed that leaf lifespan varies 30-fold among 23 species from natural and disturbed communities within a 1-km radius in the northern Amazon basin, near San Carlos de Rio Negro, Venezuela.

Vertical variation in canopy structure and CO(2) exchange of oak-maple forests: influence of ozone, nitrogen, and other factors on simulated canopy carbon gain.

Stand-level and physiological measurements were made for oak and maple species common in Wisconsin forests. Scaling relationships were identified to allow the development of a model for estimating net carbon exchange at the levels of a leaf, canopy stratum, and whole canopy. Functional relationships were determined between tissue gas exchange rates and perceived controlling variables.

Nitrofen-induced diaphragmatic hernias in rats: an animal model.

In embryological terms, pathogenesis of congenital diaphragmatic hernia (CDH) associated with pulmonary hypoplasia is still unclear. However, it is known since 1971 that Nitrofen (2,4-dichloro-phenyl-p-nitrophenyl ether) can induce anatomical malformations in rats including diaphragmatic hernias. On order to establish an animal model of the embryogenesis of CDH, the effect of Nitrofen on the developing diaphragm was studied.

Memory impairment in multiple sclerosis.

We compared the performance of 50 multiple sclerosis (MS) patients and 35 normal controls on a variety of memory tasks to determine the nature and severity of memory deficits in the MS patients and the proportion of patients affected. We also determined the relationship between memory and other cognitive functions, demographic factors, disease characteristics, depression, and psychoactive medication. We found significant differences between patients and controls on almost all memory tests.

Ecophysiology of exotic and native shrubs in Southern Wisconsin : II. Annual growth and carbon gain.

In this study we compared the aboveground growth rates of two exotic shrubs (Rhamnus cathartica and Lonicera X bella) and two native shrubs (Cornus racemosa and Prunus serotina) that are important in southern Wisconsin hardwood forests. For all species except P. serotina, aboveground growth rates in an open habitat were greater than in an understory environment.

Ecophysiology of exotic and native shrubs in Southern Wisconsin : I. Relationship of leaf characteristics, resource availability, and phenology to seasonal patterns of carbon gain.

We compared seasonal trends in photosynthesis of two naturalized exotic shrubs (Rhamnus cathartica and Lonicera X bella) and two native shrubs (Cornus racemosa and Prunus serotina) in open and understory habitats in southern Wisconsin. We examined the relationships between resource availability and leaf photosynthetic performance in these four species. All four species had similar relationships between leaf nitrogen (N) content and photosynthetic rate, but the species differed in absolute leaf N content and therefore in photosynthetic rates.

Response of Ulmus americana seedlings to varying nitrogen and water status. 2 Water and nitrogen use efficiency in photosynthesis.

Photosynthetic utilization of water and nitrogen in Ulmus americana L. seedlings was tightly linked with the relative availability of each resource. During periodic drying cycles, water use efficiency increased as predawn water potential fell from -0.

Response of Ulmus americana seedlings to varying nitrogen and water status. 1 Photosynthesis and growth.

Well-watered American elm (Ulmus americana L.) seedlings responded to increased nitrate availability with increased leaf nitrogen (N) concentration and photosynthetic rate, larger and more numerous leaves, greater total growth and greater proportional allocation of carbon to shoot than root. Plasticity of growth and carbon allocation were greater than plasticity of N concentration and photosynthetic capacity.

Pathogenesis of hypospadias--more questions than answers.

Most researchers believe that hypospadias arises from malformation of the penile urethra. However, this concept has been recently rejected, and it has been suggested that the opening of the urethra is "pushed forward" by growth of the perineum. In order to obtain more information on the development of the urethra, late stages of phallic development were studied in 220 rat embryos with scanning electron microscopy (SEM).

Role of phosphorus and nitrogen in photosynthetic and whole plant carbon gain and nutrient use efficiency in eastern white pine.

In white pine (Pinus strobus) seedlings grown in five forest soils from New York State, net photosynthetic capacity (Amax) plant was correlated with total foliar N plant (r =0.57), but was more highly correlated with total foliar P plant (r =0.82).

[Colorectal carcinoma--intracavitary sonography].

Staging of rectal carcinoma effected in 32 patients via ultrasound was re-examined on the basis of histological findings. One patient was classified in T3 by ultrasound, although histologically he belonged to the T2 stage. In no case was the spread of the tumour underestimated.

[The mesoduodenum].

In the present study an anatomical examination of ten bodies was made to describe the fixation of duodenum and pancreas to the posterior abdominal wall. It has become apparent that the shape of the posterior mesoduodenum of the first part of duodenum is rodlike. Due to the secondary retroperitoneal fixation between duodenum and pancreas a vascularized, wide-based borderline lamella remains in the area of second and third parts of the duodenum.

Depression in multiple sclerosis.

Standardized interview techniques, diagnostic criteria, and rating scales were used to assess 50 moderately disabled multiple sclerosis (MS) patients. Fifty-four percent met lifetime Research Diagnostic Criteria for major depression, with a significant increase in the rate from before to after the onset of MS symptoms. The MS patients were significantly more depressed than other medical patients described in the literature.

Quantifying plant response to ozone: a unifying theory.

Published information about the effects of ozone on plants and ecosystems is synthesized into a conceptual model to explain the response of evergreen conifers, deciduous hardwoods and agricultural crops to ambient levels of ozone pollution. The effects of ozone on carbon balance and growth of individual plants can be quantified on the basis of concentration, external dose (concentration x duration of exposure), or uptake. For an equivalent dose within a single growing season, agricultural crops are the most sensitive to ozone, with hardwoods intermediate and conifers least sensitive.

Mixed organic brain syndrome as a manifestation of systemic mastocytosis.

Systemic mastocytosis is a disease characterized by an excessive accumulation of mast cells, and associated with skin lesions, flushing, diarrhea, tachycardia, and psychiatric manifestations. In order to define more clearly the psychiatric manifestations, ten patients with this disorder underwent unstructured psychiatric interviews and a battery of psychologic testing. Both revealed a pattern of cognitive and affective changes in the majority of these patients, best categorized as an atypical or mixed organic brain syndrome.

Ambient levels of ozone reduce net photosynthesis in tree and crop species.

Experiments were conducted to measure the photosynthetic response of three crop and four tree species to realistic concentrations of ozone and (for tree species only) simulated acidic rain. The ozone concentrations were representative of those found in clean ambient air, in mildly to moderately polluted air such as occurs in much of the United States during the summer, and in more heavily polluted air. However, the highest concentrations of ozone used were lower than those found regularly in the Los Angeles area.

Agitation observed during treatment with newer hypnotic drugs.

Side effects involving agitation, e.g., sleepwalking, anger, and panic, were observed in 10 insomniac patients treated with temazepam or triazolam but not other benzodiazepines.

Electroconvulsive Therapy in Patients at High Risk for Physical Complications.

Nineteen patients had unrelieved incapacitating or life-threatening conditions likely remediable with electroconvulsive therapy (ECT). They also had coexisting medical conditions originally judged to preclude ECT because it risked unacceptable complications. ECT was administered with attempts to prevent complications, although some procedures were canceled for medical reasons.