Solitary fibrous tumor of the oral soft tissues: a clinicopathologic and immunohistochemical study of 16 cases.

We describe the clinicopathologic and immunohistochemical features of 16 solitary fibrous tumors (SFTs) originating within the oral soft tissues. There were 10 women and six men with a mean age at diagnosis of 56 years. In all cases the tumors were slow-growing, asymptomatic, submucosal growths of variable size and duration. The buccal mucosa was involved in 12 cases, and the tongue and lower lip were affected in two cases, respectively. Thirteen tumors developed on the left side of the mouth. Follow-up information was available in 10 cases and averaged 44.7 months, with no evidence of recurrence or metastasis. All 16 tumors were well circumscribed and demonstrated histologic features that were invariably benign. In all cases they were composed of an admixture of alternating hypercellular and hypocellular, collagenous zones; haphazardly arranged, cytologically bland spindle and ovoid cells that in areas were intimately intermixed with collagen; a prominent vasculature; and perivascular hyalinization. Immunohistochemically, the tumors were consistently positive for CD34, bcl-2, factor XIIIa, and vimentin, whereas 75% of the tumors were reactive for CD99. To further define the clinicopathologic profile of intraoral SFT, we include a review of the previously reported cases. We also include a comparison and brief review of the clinicopathologic and immunohistochemical features of other spindle cell tumors of the oral cavity, from which SFTs must be differentiated.

Reaction norm functions and QTL-environment interactions for flowering time in Arabidopsis thaliana.

Many plant traits are phenotypically plastic in response to resource levels that vary continuously among environments. To be able to predict phenotypes in new environments, it is useful to model reaction norms as functions, rather than as a collection of discrete character states. Flowering date and rosette leaf number were measured in 100 recombinant inbred lines of Arabidopsis thaliana, grown on a gradient of light intensity. The results show that there is genetic variation among the recombinant inbred lines for parameters of the reaction norm functions. Genetic variances for leaf number and flowering date are highest under low light conditions. Underlying quantitative trait loci (QTLs) affecting the shape of the reaction norm functions were mapped by modifying Haley & Knott (1992) regressions to include polynomial effects of the environment. Quantitative trait loci of large effect were generally insensitive to the resource gradient. Seven QTLs affecting flowering date and eight QTLs for rosette leaf number were identified, of which only two had significant effects on the linear and quadratic components of the reaction norm function. These results suggest that the genotype-environment interactions for flowering time are controlled by many minor genes, whose effects are below the detection limit in most mapping experiments.

Field tests of density-and frequency-dependent selection in Erigeron annuus (Compositae).

Selection may maintain genetic diversity in natural populations if the physical or biotic environment is variable over space and-or time. Because density and genotype frequencies can be heterogeneous, and because genotypes may differ in competitive ability, both density-and frequency-dependent selection have been considered to be potentially important evolutionary processes. To address the possibility that intraspecific interactions among plants are a source of fitness variation in Erigeron annuus, we conducted field experiments over 2 yr that were designed to examine the potential of population density, genotype frequency, and their interaction to act as selective agents. In both experiments, apomictic genotypes of Erigeron were paired. Seedlings were planted into plots that differed in density and the identity of minority and majority genotype. There was evidence for a differential effect of density among genotypes for only one year's experiment, suggesting that density-dependent selection is either weak or temporally variable. Genotype frequency had no effect on fitness in either year, and thus there was no evidence for frequency-dependent selection. In addition, the lack of a frequency ;ts density interaction demonstrates that resource partitioning, one mechanism for frequency dependence, is not strong among Erigeron genotypes. If frequency-dependent selection does occur in this species, it is either too weak to detect even in large field experiments, or occurs only in the presence of a selective agent (e.g., pathogens) that was lacking in our experiments.

Involving students in experimental design: three approaches.

Many faculty want to involve students more actively in laboratories and in experimental design. However, just "turning them loose in the lab" is time-consuming and can be frustrating for both students and faculty. We describe three different ways of providing structures for labs that require students to design their own experiments but guide the choices. One approach emphasizes invertebrate preparations and classic techniques that students can learn fairly easily. Students must read relevant primary literature and learn each technique in one week, and then design and carry out their own experiments in the next week. Another approach provides a "design framework" for the experiments so that all students are using the same technique and the same statistical comparisons, whereas their experimental questions differ widely. The third approach involves assigning the questions or problems but challenging students to design good protocols to answer these questions. In each case, there is a mixture of structure and freedom that works for the level of the students, the resources available, and our particular aims.

THE EFFECT OF INFLORESCENCE SIZE ON MALE FITNESS: EXPERIMENTAL TESTS IN THE ANDROMONOECIOUS LILY, ZIGADENUS PANICULATUS.

We studied the relationship between inflorescence size and male fitness in the andromonoecious lily Zigadenus paniculatus, using experimentally manipulated inflorescences to eliminate possible correlations between flower number, resource availability, and other floral traits. Allozyme markers were used to determine the siring success of large versus small plants in 14 arrays of plants, each array containing five large and five small plants. The inflorescence size of small plants was held constant both within and among arrays; the size of large plants was held constant within an array but was varied among arrays. Large plants sired more than half the seeds in 12 of the 14 arrays, and significantly more than half in six of these 12. However, in eight of the arrays, large plants sired significantly fewer seeds than expected on the basis of their size advantage. Furthermore, there was no significant relationship between relative size and relative siring success in comparisons among arrays. A maximum-likelihood model estimated that 28% of seeds were sired by imported pollen, with 95% confidence limits of 13% and 50%. Within these limits, high import rates tended to mask the relative success of large plants in several arrays. These results suggest that the evolution of inflorescence size in Z. paniculatus is at least partly driven by selection for increased male success, assuming genetic variation for flower number. However, the data also support a growing body of evidence that estimates of male fitness in plants can be highly variable. We discuss the sources of this variability and the possible effects of inflorescence design on the relationship between inflorescence size and fitness.

Exobiology research on Space Station Freedom.

The Gas-Grain Simulation Facility (GGSF) is a multidisciplinary experiment laboratory being developed by NASA at Ames Research Center for delivery to Space Station Freedom in 1998. This facility will employ the low-gravity environment of the Space Station to enable aerosol experiments of much longer duration than is possible in any ground-based laboratory. Studies of fractal aggregates that are impossible to sustain on Earth will also be enabled. Three research areas within exobiology that will benefit from the GGSF are described here. An analysis of the needs of this research and of other suggested experiments has produced a list of science requirements which the facility design must accommodate. A GGSF design concept developed in the first stage of flight hardware development to meet these requirements is also described.

Vascular responsiveness in the unstressed borderline hypertensive rat.

This study compares vascular responses of unstressed borderline hypertensive rats (BHR) to age-matched Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Rings of thoracic aorta were mounted for isometric force determinations in tissue baths. Cumulative additions of phenylephrine (PE) or serotonin (5-HT) produced contractile responses in BHR aorta that were less than WKY but greater than SHR. Removing the endothelium increased force development to both agonists, with BHR showing the greatest increase. Based on EC50 determinations, no differences in PE sensitivity existed between groups, although in response to 5-HT, rings from SHR were significantly more sensitive than WKY. While the sensitivity of all rings increased with denuding, BHR showed a greater relative increase in sensitivity than WKY or SHR (intact EC50 divided by denuded EC50) to both PE and 5-HT. This suggests that there may be greater endothelium-derived relaxation in BHR than in WKY or SHR. In rings precontracted with 1 microM PE, the cumulative addition of acetylcholine resulted in greater relaxation in BHR than in SHR and WKY preparations. Thus, rings from unstressed BHR, which have only slightly higher blood pressures than WKY rats, demonstrate greater endothelium-mediated relaxation than WKY or SHR. Increased endothelium-derived relaxation may represent a possible mechanism for masking hypertension in BHR that is compromised as a result of exposure to a chronic stress paradigm.

Calcium mobilization and sensitivity in intact and triton skinned aorta from thyropathologic rats.

Calcium mobilization and sensitivity in aortic rings from hyperthyroid, hypothyroid, and euthyroid rats was examined. The magnitudes of contractions were measured in rings consecutively exposed to phenylephrine (1 microM) incubated in normal physiological saline (PSS), in calcium-free PSS and in normal PSS containing nifedipine (1 microM). By comparing the generated tension under these three conditions it was possible to estimate the contributions of calcium release from the sarcoplasmic reticulum (SR), of influx through voltage gated calcium channels (VGCC), and of influx through receptor operated calcium channels (ROCC). The comparison revealed no change in the contribution of SR calcium release in the three thyroid states, but showed increased VGCC influx and decreased ROCC influx in hyperthyroid rings. No changes were seen in the hypothyroid state. When rings were chemically "skinned" with triton X-100 and subsequently contracted with increasing concentrations of free calcium, dose response curves were not significantly different among rings from the three thyroid states. This suggests that changes in tension development in hyperthyroid aortic tissue may be due, in part, to alterations in membrane calcium influx rather than to SR calcium release or modified calcium activation of contractile elements.

Regional differences in serotonergic contractile sensitivity mediated by 5-HT2 receptors in rat aorta.

The present studies examined serotonergic contractile sensitivity mediated by 5-HT2 receptors in thoracic and abdominal regions of rat aorta. Increasing concentrations of 5-HT (10 nM-100 microM) in the presence or absence of the selective 5-HT2 antagonist ketanserin (5 nM) produced differential concentration-response curves in thoracic and abdominal aortic ring preparations. Abdominal aortic preparations were significantly more sensitive to 5-HT than thoracic regions. Regional variations in maximal response produced by 5-HT were not observed. Ketanserin produced distinct rightward shifts in the 5-HT concentration-response curves, revealing a similar profile of sensitivity in thoracic and abdominal aorta. These data suggest that regional patterns in 5-HT-induced contractile responses in rat aorta are mediated by 5-HT2 sites exhibiting differential, site specific sensitivity.

Double-blind comparisons of slow-release theophylline, ketotifen and placebo for prophylaxis of asthma in young children.

Clinical trials of slow-release theophylline and ketotifen as prophylaxis against asthma in 18 young children suggested that both drugs had some efficacy. The theophylline was more effective and produced reduction in salbutamol usage as well as an increase in peak expiratory flow rates. Transient nausea and vomiting was commoner during theophylline treatment but did not usually necessitate discontinuing therapy.

A controlled comparison of slow-release theophylline, ketotifen and placebo in the prophylaxis of asthma in young children.

A double blind crossover comparison of slow-release theophylline, ketotifen and placebo was carried out in 18 young children with perennial asthma. Theophylline significantly reduced symptoms and increased the mean peak expiratory flow rate. Transient nausea and vomiting was commoner during theophylline treatment but did not usually necessitate discontinuance of therapy.

A study of the role of immunological factors in the pathogenesis of the anaemia of acute malaria.

Children with acute Plasmodium falciparum malaria and anemia were investigated to see if immunological factors could be implicated in the pathogenesis of their anaemia. Direct Coombs tests using an anti-whole immunoglobulin antiserum were negative in all 12 children tested but two had positive tests with antisera to C3b and C3d. Low plasma levels of C3 and C4 were found but these were not significantly different from values found in a group of children with acute malaria who were not anaemic. Serum levels of immune complexes were normal at the time of their presentation at hospital with anaemia but were elevated one month later. Incubation of group O rhesus-negative red cells in a serum pool obtained from children with acute malaria and anaemia did not cause enhanced haemolysis or reduce their survival time on injection into mice. Splenic uptake of red cells was, however, significantly enhanced. We conclude that the anaemia of acute malaria is due mainly to destruction of red cells by malaria parasites and to enhanced erythrophagocytosis of normal cells.

Diagnosis of acute bacterial pneumonia in Nigerian children. Value of needle aspiration of lung of countercurrent immunoelectrophoresis.

Eighty-eight Nigerian children with untreated, severe, acute pneumonia were investigated by standard bacteriological techniques (blood culture and culture of pharyngeal secretions) and by needle aspiration of the consolidated lung. Countercurrent immunoelectrophoresis (CIE) against grouped pneumococcal and Haemophilus influenzae type b antisera was carried out on serum samples from 45 patients. The aetiology of pneumonia was shown by examination of the needle aspirate in 70/88 patients (79%), by CIE in 9/45 patients (20%), and by blood culture in 4/36 patients (11%). Overall, a bacterial cause for pneumonia was shown in 73/88 patients (83%). The results of pharyngeal culture were misleading when compared with cultures of needle aspirates. The prediction of aetiology from the radiological appearance was alos inaccurate, even for labor pneumonia. Needle aspiration of the lung, with a low (5%) and minor complication rate, merits wider application in the diagnosis of acute pulmonary infections in children. Tradiational bacteriological techniques (blood culture and pharyngeal culture) are of very limited value. The place of CIE in the investigation of childhood pneumonia still needs thorough evaluation.

Aural temperature of the newborn infant.

The aural, oesophageal, and rectal temperatures of 10 term infants were monitored during changes in environmental temperature. The aural temperature in normal infants was found to be consistently higher than at any other site. It is suggested that this finding is due to the local heating effect of brain metabolism and shows the important contribution to total body heat production made by the brain. The depressed aural temperature found in an infant with hydranencephaly is cited as supporting evidence and may indicate the potential of aural temperature measurement in the investigation of cerebral metabolism.