Chronic Toxicity of 4-Nonylphenol to Two Unionid Mussels in Water-Only Exposures.

Limited studies indicate that mussels are generally insensitive to organic chemicals; however, these studies were conducted in acute or short-term exposures, and little is known about the chronic sensitivity of mussels to organic chemicals. We evaluated the chronic (28 days) toxicity of 4-nonylphenol (4-NP) to two commonly tested species of mussels: fatmucket (Lampsilis siliquoidea) and rainbow mussel (Villosa iris). By the end of the 28 days chronic exposures, mean survival was ≥93% in all treatments, but the mean dry weight and biomass of mussels at the highest exposure concentrations were significantly reduced relative to the control. The 20% effect concentrations were similar between the two species. When compared to all other tested species, fatmucket and rainbow mussels are among the top four most sensitive species to 4-NP. However, U.S. Environmental Protection Agency chronic water quality criterion of 6.6 µg 4-NP/L should protect the two mussel species.

Kidney Cell-Adapted Infectious Bronchitis ArkDPI Vaccine is Stable and Protective.

We previously demonstrated that adaptation of an embryo-attenuated infectious bronchitis virus (IBV) Arkansas (Ark) Delmarva Poultry Industry (DPI)-derived vaccine to chicken embryo kidney (CEK) cells (CEKp7) shifted the virus population towards homogeneity in spike (S) and nonstructural protein genes. Moreover, the typical Ark vaccine subpopulations emerging in chickens vaccinated with commercial Ark vaccines were not detected in chickens vaccinated with CEKp7, indicating that kidney-cell adaptation drastically increased the stability of the vaccine virus population in chickens. In the current study both conventional and next-generation sequencing results show that the changes achieved during CEK adaptation remained after five back passages in embryonated chicken egg (ECE). In a first protection study 1-day-old chickens were vaccinated with 104.0 or 105.0 50% embryo infectious doses (EID50)/chicken of the second ECE back passage of CEKp7 (CEKp7e2) and demonstrated protection against Ark virulent (106.0 EID50) challenge. In a second protection trial, protection by CEKp7e2 was compared with protection conferred by an attenuated commercial ArkDPI-derived vaccine different from that which the CEK-adapted virus originated. All vaccinated chicken groups showed a significant reduction of respiratory signs and viral load after Ark virulent challenge compared to unvaccinated-challenged controls. In CEKp7e2 vaccinated chickens viral subpopulations different from the challenge virus were detected after challenge in a marginal number (7%-8%) of chickens. In contrast, IBV S1 sequences that differed from the predominant population in the challenge virus were detected after challenge in a large number (77%) of chickens vaccinated with the commercial Ark attenuated vaccine. The CEK-adapted IBV ArkDPI-derived vaccine is a stable and effective vaccine, which drastically reduces the emergence of Ark-like viruses both at vaccination and after challenge.

Genetic variation and constraints on the evolution of defense against spittlebug (Philaenus spumarius) herbivory in Mimulus guttatus.

Plants mediate carbon into most ecosystems and are thus under persistent attack by diverse enemies. The evolution of defense against such assaults will depend on the availability of genetic variation, as well as the costs and constraints on defense. We estimated the magnitude of genetic variation for defense against spittlebug (Philaenus spumarius) herbivory in Mimulus guttatus using a diallel cross-grown in a greenhouse. Except for flowering time, additive genetic variation for the plant traits we measured was negligible, regardless of herbivory environment. In contrast, nonadditive genetic variation contributed significantly to all plant traits measured. We found significant additive genetic variation among plants for biomass of adult spittlebugs, suggesting heritability for resistance to herbivory. The other putative resistance trait measured, spittlebug maturation time, was not significantly heritable. We found no evidence for significant genetic variation for tolerance to herbivory except for a small non-nuclear paternal contribution to tolerance for flower number. Additive genetic correlations indicated that more resistant plant genotypes (in terms of adult spittlebug biomass) were also smaller in the absence of spittlebugs, suggesting a potential cost of resistance to herbivory. We found no other significant genetic correlations indicating a cost of defense, nor did we find evidence for a tradeoff between resistance and tolerance to herbivory. Overall, these results suggest the future adaptive evolution of tolerance to spittlebugs in this population will be limited primarily by available genetic variation, whereas the future evolution of antibiosis resistance may be constrained by allocation costs of resistance.

Remodeling of lung interstitium but not resistance vessels in canine pacing-induced heart failure.

We previously showed that pacing-induced heart failure in dogs results in an enhancement of pulmonary vascular reactivity. In the present study we hypothesized that enhanced matrix deposition and structural remodeling of lung resistance microvessels would underlie these functional changes. Using biochemical measures, we found no difference in the normalized lung content of hyaluronan, uronic acid, and collagen between control dogs and dogs paced for 1 mo, although lung dry weight and noncollagen protein content increased significantly in the paced group (P < 0.05). From separate Formalin-fixed lung lobes, 5-microm frozen sections were prepared and stained with Masson's trichrome, and vascular structure was evaluated using standard morphometric techniques. When perivascular fluid cuffs were excluded from the measure of wall thickness, collagen and media volume fractions in any size range did not differ between paced and control groups. Similarly, in the paced group, medial thickness in <400-microm arterial or venular microvessels did not vary significantly from that in the controls. In contrast, the relationship of interstitial fluid pressure to lung water was significantly shifted to the right in the paced group, such that normal tissue pressures were observed, despite the increased water content. We conclude that although 1 mo of pacing-induced heart failure results in altered interstitial function, the attendant pulmonary hypertension and/or hormonal responses are insufficient to induce medial hypertrophy or other remodeling of the extra-alveolar microvasculature.

Phosphotyrosine phosphatase and tyrosine kinase inhibition modulate airway pressure-induced lung injury.

We determined whether drugs which modulate the state of protein tyrosine phosphorylation could alter the threshold for high airway pressure-induced microvascular injury in isolated perfused rat lungs. Lungs were ventilated for successive 30-min periods with peak inflation pressures (PIP) of 7, 20, 30, and 35 cmH2O followed by measurement of the capillary filtration coefficient (Kfc), a sensitive index of hydraulic conductance. In untreated control lungs, Kfc increased by 1.3- and 3.3-fold relative to baseline (7 cmH2O PIP) after ventilation with 30 and 35 cmH2O PIP. However, in lungs treated with 100 microM phenylarsine oxide (a phosphotyrosine phosphatase inhibitor), Kfc increased by 4.7- and 16.4-fold relative to baseline at these PIP values. In lungs treated with 50 microM genistein (a tyrosine kinase inhibitor), Kfc increased significantly only at 35 cmH2O PIP, and the three groups were significantly different from each other. Thus phosphotyrosine phosphatase inhibition increased the susceptibility of rat lungs to high-PIP injury, and tyrosine kinase inhibition attenuated the injury relative to the high-PIP control lungs.

Involvement of cytochrome P-450 enzyme activity in the control of microvascular permeability in canine lung.

Products of cytochrome P-450 enzymes may play a role in capacitative Ca2+ entry in endothelial cells, which can promote a rise in vascular permeability. Thapsigargin (150 nM) stimulated capacitative Ca2+ entry and increased the capillary filtration coefficient (Kf,c) in isolated normal canine lung lobes. Pretreatment of the lobes with cytochrome P-450 inhibitors clotrimazole (10 microM) or 17-octadecynoic acid (5 microM) abolished the thapsigargin-induced increases in Kf,c. Because clotrimazole also blocks Ca2+-activated K+ channels, the K+-channel blocker tetraethylammonium (10 mM) was used to ensure that permeability was not influenced by this mechanism. Tetraethylammonium did not affect thapsigargin-induced permeability. The effects of the cytochrome P-450 arachidonic acid metabolite 5,6-epoxyeicosatrienoic acid (EET) were also investigated in lobes taken from control dogs and dogs with pacing-induced heart failure (paced at 245 beats/min for 4 wk). 5,6-EET (10 microM) significantly increased Kf,c in lobes from the control but not from the paced animals. We conclude that cytochrome P-450 metabolites are involved in mediating microvascular permeability in normal canine lungs, but an absence of 5,6-EET after heart failure does not explain the resistance of lungs from these animals to permeability changes.

Ablation of lung endothelial injury after pacing-induced heart failure is related to alterations in Ca2+ signaling.

We have previously shown that ANG II increases microvascular permeability in normal dog lungs but not after pacing-induced heart failure. This study investigated how ANG II induces permeability in isolated blood-perfused canine lung lobes and what alterations occur during heart failure. In normal lobes, the protein kinase C (PKC) inhibitors staurosporine (500 nM) or chelerythrine (10 microM) did not modify ANG II-induced increases in the capillary filtration coefficient (Kf,c, ml . min-1 . cmH2O-1 . 100 g-1; an index of microvascular permeability), suggesting that PKC is not involved. Thapsigargin (150 nM) was used to stimulate capacitative Ca2+ entry in lobes from control dogs and dogs paced at 245 beats/min for 4 wk to induce heart failure. In control lobes, Kf,c rose after thapsigargin, from 0.06 +/- 0.01 to 0.17 +/- 0.03 ml . min-1 . cmH2O-1 . 100 g-1 (mean +/- SE, P < 0.05) but did not change in the paced group. A Ca2+ ionophore, A-23187, increased Kf,c in both control (10 microM; 0.05 +/- 0.01 to 0.17 +/- 0.05 ml . min-1 . cmH2O-1 . 100 g-1, P < 0.05) and pace (5 microM; 0.06 +/- 0.01 to 0. 21 +/- 0.07 ml . min-1 . cmH2O-1 . 100 g-1, P < 0.05) lobes, indicating that increasing intracellular Ca2+ is sufficient to induce pulmonary microvascular permeability after pacing. We conclude that during heart failure, Ca2+ signaling within the pulmonary microvascular endothelium is altered.

Gadolinium prevents high airway pressure-induced permeability increases in isolated rat lungs.

To determine the initial signaling event in the vascular permeability increase after high airway pressure injury, we compared groups of lungs ventilated at different peak inflation pressures (PIPs) with (gadolinium group) and without (control group) infusion of 20 microM gadolinium chloride, an inhibitor of endothelial stretch-activated cation channels. Microvascular permeability was assessed by using the capillary filtration coefficient (Kfc), a measure of capillary hydraulic conductivity. Kfc was measured after ventilation for 30-min periods with 7, 20, and 30 cmH2O PIP with 3 cmH2O positive end-expiratory pressure and with 35 cmH2O PIP with 8 cmH2O positive end-expiratory pressure. In control lungs, Kfc increased significantly to 1.8 and 3.7 times baseline after 30 and 35 cmH2O PIP, respectively. In the gadolinium group, Kfc was unchanged from baseline (0.060 +/- 0.010 ml . min-1 . cmH2O-1 . 100 g-1) after any PIP ventilation period. Pulmonary vascular resistance increased significantly from baseline in both groups before the last Kfc measurement but was not different between groups. These results suggest that microvascular permeability is actively modulated by a cellular response to mechanical injury and that stretch-activated cation channels may initiate this response through increases in intracellular calcium concentration.

Noise-induced tuning curve changes in mechanoreceptors.

Fibers from the tibial nerve of rat were isolated and spike activity recorded using monopolar hook electrodes. The receptive field (RF) of each recorded unit on the glabrous skin of the foot was mechanically stimulated with waveforms comprised of various frequency sine waves in addition to increasing levels of white noise. Single-unit responses were recorded for both rapidly adapting (RA) and slowly adapting (SA) units. Signal-to-noise ratio (SNR) of the output was quantified by the correlation coefficient (C1) between the input sine wave and the nerve responses. The addition of noise enhanced signal transmission in both RA and SA fibers. With increasing noise, the initially inverted "V"-shaped, zero-noise tuning curves for RA fibers broadened and eventually inverted. There was a large expansion of the frequencies that the RA receptor responded to with increasing noise input. On the other hand, the typical shape of the SA fiber tuning curves remained invariant, at all noise levels tested. C1 values continued to increase with larger noise input for higher frequencies, but did not do so at the lowest frequencies. For both RA and SA fibers the responses with added noise tended to be rate modulated at the low-frequency end, and followed nonlinear stochastic resonance (SR) properties at the higher frequencies. The changes in the tuning properties due to noise found here, as well as preliminary psychophysics data, imply that external noise is relevant for sensing small periodic signals in the environment. All current models of sensory perception assume that the tuning properties of receptors determined in the absence of noise are preserved during everyday tasks. Our results indicate that this is not true in a noisy environment.

Isoproterenol attenuates high vascular pressure-induced permeability increases in isolated rat lungs.

To separate the contributions of cellular and basement membrane components of the alveolar capillary barrier to the increased microvascular permeability induced by high pulmonary venous pressures (Ppv), we subjected isolated rat lungs to increases in Ppv, which increased capillary filtration coefficient (Kfc) without significant hemorrhage (31 cmH2O) and with obvious extravasation of red blood cells (43 cmH2O). Isoproterenol (20 microM) was infused in one group (Iso) to identify a reversible cellular component of injury, and residual blood volumes were measured to assess extravasation of red blood cells through ruptured basement membranes. In untreated lungs (High Ppv group), Kfc increased 6.2 +/- 1.3 and 38.3 +/- 15.2 times baseline during the 31 and 43 cmH2O Ppv states. In Iso lungs, Kfc was 36.2% (P < 0.05) and 64.3% of that in the High Ppv group at these Ppv states. Residual blood volumes calculated from tissue hemoglobin contents were significantly increased by 53-66% in the high Ppv groups, compared with low vascular pressure controls, but there was no significant difference between High Ppv and Iso groups. Thus isoproterenol significantly attenuated vascular pressure-induced Kfc increases at moderate Ppv, possibly because of an endothelial effect, but it did not affect red cell extravasation at higher vascular pressures.

Visual mental rotation of possible and impossible objects.

Participants were tested on two visual mental rotation tasks using three-dimensional "possible" and "impossible" shapes. Both types of stimuli can be easily encoded by their parts and how they are spatially organized. However, while possible shapes can also be easily encoded as a global image, it is more difficult to encode impossible shapes in such a way. Participants visually rotated both types of stimuli at comparable rates, reflecting that local representations were used in the process of visual mental rotation.

Neutrophil chemoattractants generated in two phases during reperfusion of ischemic myocardium in the rabbit. Evidence for a role for C5a and interleukin-8.

The neutrophil chemoattractants generated in a model of myocardial infarction in the anesthetized rabbit were investigated. Coronary artery occlusion was followed by reperfusion for periods from 5 min to 4.5 h. Extracts of myocardial tissue in normal and post-ischemic zones were tested for C5a and interleukin-8 (IL-8) using specific radioimmunoassays. In the post-ischemic zone, immunoreactive C5a was detected within 5 min and rose progressively to reach a plateau at 3-4.5 h. In contrast, immunoreactive IL-8 concentrations rose after a delay and were highest at the last time point tested, 4.5 h. Myeloperoxidase activity levels, an index of neutrophil accumulation, rose progressively as the concentrations of chemoattractants increased. Using cation exchange and reversed phase HPLC, immunoreactive C5a and IL-8 co-eluted with authentic standards. Fractions taken at the C5a and IL-8 peaks from reversed phase HPLC exhibited neutrophil aggregating activity which was neutralized by the respective antibody used in the radioimmunoassays. Depletion of circulating neutrophils virtually abolished immunoreactive IL-8 in the post-ischemic myocardial tissue. These observations suggest a sequential release of chemoattractants: the first, C5a is generated in interstitial fluid, followed by IL-8 generated by infiltrating neutrophils. Thus, over the time period studied, IL-8 generation would be expected to be indirectly dependent on C5a production.

Epidemic Shigella dysenteriae type 1 in Burundi: panresistance and implications for prevention.

An epidemic of Shigella dysenteriae type 1 infections has affected Africa since 1979. Reported dysentery cases increase sharply in Burundi during September through December. Of stool samples from 189 patients reporting bloody diarrhea in November 1990, a pathogen was identified in 123 (65%). The pathogen was S. dysenteriae type 1 in 82 (67%). All S. dysenteriae type 1 isolates were resistant to ampicillin, chloramphenicol, nalidixic acid, streptomycin, sulfisoxazole, tetracycline, and trimethoprim-sulfamethoxazole. Thirty-two specimens (26%) yielded other Shigella species. Patients with S. dysenteriae type 1 were more likely than those with other Shigella infections to have abdominal pain, "lots of blood" in the stool, blood in the stool specimen examined by the interviewer, recent contact with a person with dysentery, or recent antimicrobial treatment. Thus, the seasonal increase in dysentery was due largely to multidrug-resistant S. dysenteriae type 1, clinical and epidemiologic features may predict such infection, and efforts to control this epidemic must focus on preventing transmission.

Pathogen-specific risk factors and protective factors for acute diarrheal disease in urban Brazilian infants.

To evaluate potential risk factors and protective factors for acute diarrheal disease in urban infants, 500 infants < or = 12 months old with diarrhea and 500 age-matched control subjects coming to a São Paulo emergency room were studied. On multivariate analysis, these apparently sporadic community-acquired cases of diarrhea were significantly associated with hospitalization in the month before onset (odds ratio [OR], 3.4), day care center exposure (OR, 2.0), prior diarrhea in another household member (OR, 4.4), and low family income (OR, 1.8). Breast-feeding infants < 6 months old (OR, 0.3) and boiling household drinking water (OR, 0.4) were protective. Enteropathogenic Escherichia coli (EPEC; OR, 12.0) and Salmonella (OR, 7/0, discordant pairs) infections were associated with prior hospitalization, rotavirus infections were associated with day care (OR, 6/0), and breast-feeding was protective against EPEC infections (OR, 0.1). These results suggest that certain preventive strategies can prevent a substantial proportion of cases of diarrheal disease in Brazilian infants.

Enteropathogens associated with acute diarrheal disease in urban infants in São Paulo, Brazil.

To determine the prevalence and epidemiology of enteropathogens in acute infantile diarrhea, 500 infants less than or equal to 12 months of age with diarrhea and 500 age-matched control subjects coming to a São Paulo emergency room were studied. Enteropathogens were identified in 55% of case infants and 10% of controls; enteropathogenic Escherichia coli (EPEC) of classic EPEC serotypes producing EPEC adherence factor (EAF) (26% of case infants), rotavirus (14%), Salmonella species (8%), enterotoxigenic E. coli (7%), and Shigella species (5%) were associated with diarrhea. Isolation of EAF+ classic EPEC decreased with increasing age of cases and peaked in spring, whereas rotavirus was least common in early infancy and peaked in fall and winter. Bloody stool had a 36% positive predictive value for Shigella infection, EAF+ classic EPEC were highly resistant to antimicrobial drugs. Among poor São Paulo infants, EAF+ classic EPEC equaled or exceeded rotavirus throughout the year as a cause of diarrhea bringing children to medical attention.

Foodborne disease outbreaks, 5-year summary, 1983-1987.

This report summarizes data from foodborne disease outbreaks reported to CDC from 1983 through 1987. With a few exceptions, an outbreak is defined as an incident in which two or more persons experience a similar illness and food is implicated. During this period, 2,397 outbreaks of foodborne disease were reported, representing 91,678 cases. Among outbreaks in which the etiology was determined, bacterial pathogens caused the largest number of outbreaks (66%) and cases (92%). Chemical agents caused 26% of outbreaks and 2% of cases. Parasites caused 4% of outbreaks and less than 1% of cases, and viruses caused 5% of outbreaks and 5% of cases. The discrepancies between the number of outbreaks and the number of cases attributed to each etiologic agent emphasizes the importance of evaluating both numbers before drawing conclusions. The etiologic agent was not determined in 62% of outbreaks, reflecting the need for improved investigative skills. The number of outbreaks reported by this surveillance system is only a small fraction of the true number that occur. The likelihood of an outbreak's being reported depends on many factors, such as ease of recognition and ease of laboratory confirmation. Sporadic foodborne illness is far more common and is not included in this report.