Assessing land use, sedimentation, and water quality stressors as predictors of coral reef condition in St. Thomas, U.S. Virgin Islands.

Coral reef condition on the south shore of St. Thomas, U.S. Virgin Islands, was assessed at various distances from Charlotte Amalie, the most densely populated city on the island. Human influence in the area includes industrial activity, wastewater discharge, cruise ship docks, and impervious surfaces throughout the watershed. Anthropogenic activity was characterized using a landscape development intensity (LDI) index, sedimentation threat (ST) estimates, and water quality (WQ) impairments in the near-coastal zone. Total three-dimensional coral cover, reef rugosity, and coral diversity had significant negative coefficients for LDI index, as did densities of dominant species Orbicella annularis, Orbicella franksi, Montastraea cavernosa, Orbicella faveolata, and Porites porites. However, overall stony coral colony density was not significantly correlated with stressors. Positive relationships between reef rugosity and ST, between coral diversity and ST, and between coral diversity and WQ were unexpected because these stressors are generally thought to negatively influence coral growth and health. Sponge density was greater with higher disturbance indicators (ST and WQ), consistent with reports of greater resistance by sponges to degraded water quality compared to stony corals. The highest FoRAM (Foraminifera in Reef Assessment and Monitoring) indices indicating good water quality were found offshore from the main island and outside the harbor. Negative associations between stony coral metrics and LDI index have been reported elsewhere in the Caribbean and highlight LDI index potential as a spatial tool to characterize land-based anthropogenic stressor gradients relevant to coral reefs. Fewer relationships were found with an integrated stressor index but with similar trends in response direction.

Contrasting responses of coral reef fauna and foraminiferal assemblages to human influence in La Parguera, Puerto Rico.

Coral reef biota including stony corals, sponges, gorgonians, fish, benthic macroinvertebrates and foraminifera were surveyed in coastal waters near La Parguera, in southwestern Puerto Rico. The goal was to evaluate sensitivity of coral reef biological indicators to human disturbance. Proxies for human disturbance were measured as distance to town (DTT) and rankings of a low-level sediment contamination gradient analyzed from a previous study. Contaminant rank and DTT showed that percent mud, stony coral taxa richness, reef rugosity, and numbers of invertebrates and sponges were higher at sites closer to human disturbance, but a foraminiferal assemblage index was significantly lower at sites with higher proxies for human disturbance. Fish indicators showed no significant relationships with human activity, but associations between fish community measures and certain measures of stony corals, gorgonians and sponges were found. Contrasting responses between foraminifera and reef organisms may be due to greater exposure and sensitivity of foraminifera to sediment contaminants.

Relationships between tissue contaminants and defense-related characteristics of oysters (Crassostrea virginica) from five Florida bays.

Evidence linking bivalve defense responses with pollutant exposure is increasing. Contaminant effects on immune or defense responses could influence the ability of an organism to resist infectious disease. This study explored relationships between xenobiotic chemicals accumulated in oyster (Crassostrea virginica) tissue and various measures of putative oyster internal defense activities and physiological condition. Defense-related and physiological measurements were made on individual oysters collected from 22 sites at five Florida bays and pooled oyster tissue from each site was analyzed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals and certain pesticides. Chemical concentrations, physiological condition, and hemocyte and hemolymph characteristics varied across bays and among sites within a bay. Within-bay comparisons showed that sites with high oyster defense-related activities often had accompanying high tissue concentrations of one or more classes of xenobiotic chemicals. Correlation analysis performed across bays demonstrated significant positive relationships between most defense-related characteristics and at least one contaminant, including various PAH, PCB and trace metal analytes. In combination with other recent studies, these results strengthen the hypothesis that certain xenobiotic chemicals may be associated with elevated oyster hemocyte activities, even though the ultimate influence on disease resistance remains unknown.

A survey of oysters Crassostrea virginica from Tampa Bay, Florida: associations of internal defense measurements with contaminant burdens.

Oysters from 16 sites in Tampa Bay, Florida, were collected during a 6-week period in winter 1993 and analyzed for both biological characteristics and tissue chemical concentrations. Using previous sediment contamination and toxicity data, oyster tissues from the selected sites were expected to exhibit a wide range in both quantity and type of chemicals. Chemical analysis showed tissue concentrations at some of these sites to be greater than national averages, as reported by the National Status and Trends Mussel Watch Program, for total PAH, total PCB, total chlordanes, DDT, Cu, Pb and Zn. Measures of oyster internal defense, including hemocyte density, rate of locomotion and superoxide generation, varied significantly among sites and were generally higher at sites with higher tissue concentrations of xenobiotic chemicals. Potential associations between oyster defense characteristics and accumulated chemical contaminants, either singly or in chemical classes, were explored using correlation analysis and a composited ranking procedure. Positive relationships were found for hemocyte characteristics with certain trace metal (Cu, Sn and Zn) and PAH analytes, whereas negative relationships were found with certain PCB and pesticide analytes. Heightened defenses in contaminated conditions may reflect a hemocyte process for sequestration and detoxification of environmental contaminants. Oysters from four of the 16 sites were additionally collected in June and September 1993 and site-related differences did not closely parallel those obtained in winter. Seasonal environmental factors may have altered contaminant-related differences among sites.

Patient preferences for management of first-trimester incomplete spontaneous abortion.

BACKGROUND: Approximately 15% of clinically recognized pregnancies end in miscarriage. The probabilities for successful outcome between expectant treatment and dilatation and curettage for management of many first-trimester incomplete spontaneous abortions are comparable. The goal of this study was to assess patient preferences for expectant treatment compared with dilatation and curettage, and the effect of physician recommendation on these preferences. METHODS: During individual telephone interviews, patients were read a case scenario and two treatment options. They were educated about the estimated risks, outcomes, and costs associated with each option. The patients then verbally completed a questionnaire assessing their likelihood of choosing each option, their reasons for their choice, and the effect of physician recommendation. RESULTS: Seventy-five women between the ages of 18 and 45 years, recruited from a university-affiliated family medicine clinic, were interviewed. Of these women, 27 had experienced spontaneous abortion (cases), and 48 had not (controls). Seventy-two percent of all participants (confidence interval 0.62-0.82) were likely or highly likely to choose expectant treatment, 23% of women rated the likelihood of choosing this option unlikely or highly unlikely, and 5% were uncertain. No significant difference existed between the case and control populations regarding choice of treatment (P = .566). One half of the women stated they would change their choice given a physician's recommendation (55% control, 40% case, P < .03) CONCLUSIONS: Participants indicated a strong preference for expectant treatment, but gave physician recommendation a significant role in the final decision. Physicians need to offer both options to patients and consider individual patient preferences when making recommendations regarding management of first-trimester incomplete spontaneous abortion.

Stimulus exposure effects in human associative learning.

Learning that one cue (CS) predicts a second, salient cue (US) can often be slowed by prior exposure to one or both stimuli. In animals, CS-US learning is more strongly retarded following uncorrelated exposure to both CS and US than following exposure to the US alone. In this paper we present several studies showing a similar effect in humans, using a computer-based task. Experiments 1 and 2 used a between-groups design and demonstrated a strong CS/US exposure effect, whether or not the US was signalled by a neutral cue during exposure. Experiment 3 demonstrated similar effects using a within-subjects design. Overall, these results are consistent with several theoretical interpretations and suggest that uncorrelated CS/US exposure leads to a robust retardation of subsequent CS-US learning in humans.

Factors influencing in vitro killing of bacteria by hemocytes of the eastern oyster (Crassostrea virginica).

A tetrazolium dye reduction assay was used to study factors governing the killing of bacteria by oyster hemocytes. In vitro tests were performed on bacterial strains by using hemocytes from oysters collected from the same location in winter and summer. Vibrio parahaemolyticus strains, altered in motility or colonial morphology (opaque and translucent), and Listeria monocytogenes mutants lacking catalase, superoxide dismutase, hemolysin, and phospholipase activities were examined in winter and summer. Vibrio vulnificus strains, opaque and translucent (with and without capsules), were examined only in summer. Among V. parahaemolyticus and L. monocytogenes, significantly (P < 0.05) higher levels of killing by hemocytes were observed in summer than in winter. L. monocytogenes was more resistant than V. parahaemolyticus or V. vulnificus to the bactericidal activity of hemocytes. In winter, both translucent strains of V. parahaemolyticus showed significantly (P < 0.05) higher susceptibility to killing by hemocytes than did the wild-type opaque strain. In summer, only one of the V. parahaemolyticus translucent strains showed significantly (P < 0.05) higher susceptibility to killing by hemocytes than did the wild-type opaque strain. No significant differences (P > 0.05) in killing by hemocytes were observed between opaque (encapsulated) and translucent (nonencapsulated) pairs of V. vulnificus. Activities of 19 hydrolytic enzymes were measured in oyster hemolymph collected in winter and summer. Only one enzyme, esterase (C4), showed a seasonal difference in activity (higher in winter than in summer). These results suggest that differences existed between bacterial genera in their ability to evade killing by oyster hemocytes, that a trait(s) associated with the opaque phenotype may have enabled V. parahaemolyticus to evade killing by the oyster's cellular defense, and that bactericidal activity of hemocytes was greater in summer than in winter.

Expectant, medical, or surgical treatment of spontaneous abortion in first trimester of pregnancy? A pooled quantitative literature evaluation.

BACKGROUND: Spontaneous abortion is a common problem in everyday clinical practice, accounting for 15 to 20 percent of all recognized pregnancies. The traditional treatment of this problem has been surgical, emptying the uterus by dilatation and curettage (D&C). Recent therapeutic and laboratory advances call surgical therapy into question for many patients. It is believed that this pooled quantitative literature evaluation is the first with the goal to clarify the roles of expectant, medical, and surgical treatment of this common problem. METHODS: The literature review was focused on published studies in the English language of outcomes of therapy for spontaneous abortion in the first trimester. We looked for both observational and randomized controlled trials. A successful outcome of treatment required that three criteria be met: vaginal bleeding stopped by 3 weeks, products of conception fully expelled by 2 weeks, and absence of complications. Pooled weighted average success estimates and standard errors were determined for each study; 95 percent confidence intervals were calculated for each form of treatment. Sensitivity analysis compared randomized controlled trials with observational studies for both expectant and surgical treatment. RESULTS: Of the 31 studies retrieved, 18 met inclusion criteria, including 9 involving expectant treatment (545 pooled patients), 3 for medical treatment (prostaglandin or antiprogesterone agents) (198 pooled patients), and 10 for surgical treatment (D&C) (1408 pooled patients). Successful outcomes were found in 92.5 percent of patients receiving expectant treatment, in 93.6 percent of those undergoing D&C, and in 51.5 percent of patients receiving medical treatment. CONCLUSIONS: Expectant management of spontaneous abortion in the first trimester is safe and effective for many afebrile patients whose blood pressure and heart rate are stable and who have no excess bleeding or unacceptable pain. Transvaginal sonographic studies might be useful in patient selection, and serial chorionic gonadotropin monitoring should be considered while observing the initial course of expectant treatment. Currently there is insufficient evidence to support medical therapy of spontaneous abortion, and further research is needed to clarify the more limited role of surgical treatment.

Perkinsus marinus tissue distribution and seasonal variation in oysters Crassostrea virginica from Florida, Virginia and New York.

Perkinsus marinus infection intensity was measured in eastern oysters Crassostrea virginica collected in October and December 1993, and March, May, and July 1994 from 3 U.S. sites: Apalachicola Bay (FL), Chesapeake Bay (VA), and Oyster Bay (NY). Gill, mantle, digestive gland, adductor muscle, hemolymph, and remaining tissue (including gonadal material and rectum) were dissected from 20 oysters from each site at each collection time. Samples were separately diagnosed for P. marinus infections by incubation in Ray's Fluid Thioglycollate Medium (RFTM) and subsequent microscopic quantification of purified enlarged hypnospores. At all sampling times and sites, average P. marinus infection intensity (g wet wt tissue-1 or ml hemolymph-1) was lowest in hemolymph samples, and generally highest in the digestive gland. Perkinsus marinus prevalence was 100% at both FL and NY sites for each of the 5 collection times, and, for the VA site, was less than 100% in only 1 month (May 1994). Seasonal intensity patterns and mean total body burdens differed among the sites. Average body burden was highest in VA during October and progressively declined to a minimum in May. This decline was probably due to mortality of heavily infected oysters and diminution of parasite activity associated with colder temperatures and reduced salinities. Intensities varied little during the months of October and December at both the FL and NY sites. Minimum average intensities were observed in March in FL oysters and May in NY oysters. Relatively high P. marinus infection levels that persisted throughout the winter in NY oysters compared with VA oysters could reflect constant high salinity in Long Island Sound which favors parasite activity, and also rapid decline in temperature in the fall that may have prevented epizootic oyster mortalities.

Purification of recombinant human precursor acid alpha-glucosidase.

Large quantities of recombinant acid alpha-glucosidase are needed for in vivo experimentation of enzyme replacement therapy in Pompe disease. We describe a new purification method for the purification of this recombinant enzyme from tissue culture medium consisting of concanavalin A affinity chromatography, hydrophobic interaction chromatography, affinity chromatography on Superdex, and anion exchange chromatography. The new method is amenable to scale up, and has increased speed, and improved reproducibility with similar high yield and purification efficiency when compared to previous methods.

Extending models of hippocampal function in animal conditioning to human amnesia.

Although most analyses of amnesia have focused on the loss of explicit declarative and episodic memories following hippocampal-region damage, considerable insights into amnesia can also be realised by studying hippocampal function in simple procedural, or habit-based, associative learning tasks. Although many simple forms of associative learning are unimpaired by hippocampal damage, more complex tasks which require sensitivity to unreinforced stimuli, configurations of multiple stimuli, or contextual information are impaired by hippocampal damage. In several recent papers we have developed a computational theory of hippocampal function which argues that this brain region plays a critical role in the formation of new stimulus representations during learning (Gluck & Myers, 1993, 1995; Myers & Gluck, 1996; Myers, Gluck, & Granger, 1995). We have applied this theory to a broad range of empirical data from studies of classical conditioning in both intact and hippocampal-lesioned animals, and the model correctly accounts for these data. The classical conditioning paradigm can be adapted for use in humans, and similar results for acquisition are obtained in both normal and hippocampal-damaged humans. More recently, we have begun to address an important set of category learning studies in both normals and hippocampal-damaged amnesics. This work integrates experimental studies of amnesic category learning (Knowlton, Squire, & Gluck, 1994) with theoretical accounts of associative learning, and builds on previously established behavioural correspondences between animal conditioning and human category learning (Gluck & Bower, 1988a). Our work to date illustrates some initial progress towards a more integrative understanding of hippocampal function in both animal and human learning, which may be useful in guiding further empirical and theoretical research in human memory and amnesia.

Late-training amnesic deficits in probabilistic category learning: a neurocomputational analysis.

Building upon earlier behavioral models of animal and human learning, we explore how a psychobiological model of animal conditioning can be applied to amnesic category learning. In particular, we show that the late-training deficit found in Knowlton, Squire, and Gluck's 1994 study of amnesic category learning can be understood as a natural consequence of Gluck and Myers's (1993) theory of hippocampal-region function, a theory that has heretofore been applied only to studies of animal learning. When applied to Knowlton et al.'s category learning task, Gluck and Myers's model assumes that the hippocampal region induces new stimulus representations over multiple training trials that reflect stimulus-stimulus regularities in the training set. As such, the model expects an advantage for control subjects over hippocampal-damaged amnesic patients only later in training when control subjects have developed new hippocampal-dependent stimulus representations; in contrast, both groups are expected to show equivalent performance early in training. A potentially analogous early/late distinction is described for animal studies of stimulus generalization. Our analyses suggest that careful comparisons between early and late-training differences in learning may be an important factor in understanding amnesia and the neural bases of both animal and human learning.

Changes in medial cortical blood flow with a stimulus-response compatibility task.

Previous work has suggested that human subjects engaged in tasks, like the Stroop task, that require response selection utilize the medial frontal cortex. We used positron emission tomography to measure blood flow changes in a stimulus-response compatibility task designed to maximize the demand on response selection processes. We report significant activation in the cingulate sulcus (Brodman's area 32) and a correlation of activity in this region with faster response time for an incongruent stimulus-response task.