Bi-national outbreak of Salmonella Newport infections linked to onions: the United States experience.

From 2016-2019, dry bulb onions were the suspected cause of three multistate outbreaks in the United States. We investigated a large multistate outbreak of Salmonella Newport infections that caused illnesses in both the United States and Canada in 2020. Epidemiologic, laboratory and traceback investigations were conducted to determine the source of the infections, and data were shared among U.S. and Canadian public health officials. We identified 1127 U.S. illnesses from 48 states with illness onset dates ranging from 19 June to 11 September 2020. Sixty-six per cent of ill people reported consuming red onions in the week before illness onset. Thirty-five illness sub-clusters were identified during the investigation and seventy-four per cent of sub-clusters served red onions to customers during the exposure period. Traceback for the source of onions in illness sub-clusters identified a common onion grower in Bakersfield, CA as the source of red onions, and onions were recalled at this time. Although other strains of Salmonella Newport were identified in environmental samples collected at the Bakersfield, CA grower, extensive environmental and product testing did not yield the outbreak strain. This was the third largest U.S. foodborne Salmonella outbreak in the last 30 years. It is the first U.S. multistate outbreak with a confirmed link to dry bulb onions, and it was nearly 10-fold larger than prior outbreaks with a suspected link to onions. This outbreak is notable for its size and scope, as well as the international data sharing that led to implication of red onions as the primary cause of the outbreak. Although an environmental assessment at the grower identified several factors that likely contributed to the outbreak, no main reason was identified. The expedient identification of the outbreak vehicle and response of multiple public health agencies allowed for recall and removal of product from the marketplace, and rapid messaging to both the public and industry on actions to protect consumers; these features contributed to a decrease in cases and expeditious conclusion of the outbreak.

Multistate outbreak of Salmonella Poona infections associated with imported cucumbers, 2015-2016.

We investigated a large multistate outbreak that occurred in the United States in 2015-2016. Epidemiologic, laboratory, and traceback studies were conducted to determine the source of the infections. We identified 907 case-patients from 40 states with illness onset dates ranging from July 3, 2015 to March 2, 2016. Sixty-three percent of case-patients reported consuming cucumbers in the week before illness onset. Ten illness sub-clusters linked to events or purchase locations were identified. All sub-clusters investigated received cucumbers from a single distributor which were sourced from a single grower in Mexico. Seventy-five cucumber samples were collected, 19 of which yielded the outbreak strain. Whole genome sequencing performed on 154 clinical isolates and 19 cucumber samples indicated that the sequenced isolates were closely related genetically to one another. This was the largest US foodborne disease outbreak in the last ten years and the third largest in the past 20 years. This was at least the fifth multistate outbreak caused by contaminated cucumbers since 2010. The outbreak is noteworthy because a recall was issued only 17 days after the outbreak was identified, which allowed for the removal of the contaminated cucumbers still available in commerce, unlike previous cucumber associated outbreaks. The rapid identification and response of multiple public health agencies resulted in preventing this from becoming an even larger outbreak.

The Status of SEMS Versus Plastic Stents for Benign Biliary Strictures.

PURPOSE OF REVIEW: Benign biliary strictures can be treated with plastic stents and self-expandable metal stents (SEMS). This review article delineates the latest scientific evidence for their usage. RECENT FINDINGS: Despite evolving literature on both type of stents as treatment modalities of benign biliary strictures, which encompass mainly anastomotic strictures and strictures related to chronic pancreatitis, no final conclusions can be drawn regarding the superiority of a particular stent. SEMS tend to have higher stricture resolution rates and fewer procedural requirements which are partly offset by higher stent migration and stricture recurrence rates compared with plastic stents. Additional studies focusing on new SEMS types with anti-migration features as well as cost-effectiveness calculations are necessary for clinical decision-making when treating patients with benign biliary strictures.

New drugs and strategies for management of Clostridium difficile colitis.

Approaches for management of Clostridium difficile infection continually evolve as research reveals shifts in epidemiology, microbial pathogenesis, disease severity states, and response to therapy. These new discoveries significantly impact diagnostic and therapeutic strategies, given the high morbidity associated with this common nosocomial infectious diarrhea. Critically ill patients are at an increased risk of developing diarrheal illness like C. difficile and succumbing to potentially fatal complications of this infection. Early diagnosis of severe disease state may improve patient outcomes. In this article, we review treatment strategies and new approaches for the management of C. difficile in critically ill patients.

Effects of breaks in the interval cycle on temporal tracking in pigeons.

Two experiments examined the effects of inserting a break in a cyclic interval schedule on the temporal control of keypecking responses in pigeons. In Experiment 1, pigeons were exposed to intervals that changed from 45 to 15s and returned to 45 s. A break was inserted between the last 15-s and following 45-s interval and was in effect for either 0, 60, or 120 s. Either a blackout of lights in the test chamber or turning off the response key alone signaled breaks. In Experiment 2, we examined the effects of a wider range of breaks-0, 120, and 360 s. Post-reinforcement pause (PRP) tracked changes in the interval requirement across all conditions. However, breaks in the schedule, even one lasting 360 s, did not disrupt the overall time course of responding. The only effect that a break had on temporal performance was an elevation in the rate of responding and a shorter PRP in the interval following a break. The results suggest that breaks did not affect the birds' memory for short intervals, and that the momentary increase in responding may be related to the reinforcement omission effect.

Interval timing in Siamese fighting fish (Betta splendens).

The present study evaluated the temporal performance of Siamese fighting fish (Betta splendens) given short-term exposure to four fixed interval (FI) schedules of reinforcement, FI 30, 60, 120, and 240 s, during which a reinforcer (mirror image) was given for the first response (swimming through a hoop) after the interval requirement had elapsed. Response levels were generally low early in an interval and increased as the interval elapsed; wait times and break points in an interval increased with increases in the FI requirement. The results were similar to that obtained with other species and different types of responses and reinforcers, and demonstrate that the procedure is a feasible method for studying interval timing in fish.

Habituation, memory and the brain: the dynamics of interval timing.

Memory decay is rapid at first and slower later-a feature that accounts for Jost's memory law: that old memories gain on newer ones with lapse of time. The rate-sensitive property of habituation-that recovery after spaced stimuli may be slower than after massed-provides a clue to the dynamics of memory decay. Rate-sensitive habituation can be modeled by a cascade of thresholded integrator units that have a counterpart in human brain areas identified by magnetic source imaging (MSI). The memory trace component of the multiple-time-scale model for habituation can provide a 'clock' that has the properties necessary to account for both static and dynamic properties of interval timing: static proportional and Weber-law timing as well as dynamic tracking of progressive, 'impulse' and periodic interval sequences.

A tuned-trace theory of interval-timing dynamics.

Animals on interval schedules of reinforcement can rapidly adjust a temporal dependent variable, such as wait time, to changes in the prevailing interreinforcement interval. We describe data on the effects of impulse, step, sine-cyclic, and variable-interval schedules and show that they can be explained by a tuned-trace timing model with a one-back threshold-setting rule. The model can also explain steady-state timing properties such as proportional and Weber law timing and the effects of reinforcement magnitude. The model assumes that food reinforcers and other time markers have a decaying effect (trace) with properties that can be derived from the rate-sensitive property of habituation (the multiple-time-scale model). In timing experiments, response threshold is determined by the trace value at the time of the most recent reinforcement. The model provides a partial account for the learning of multiple intervals, but does not account for scalloping and other postpause features of responding on interval schedules and has some problems with square-wave schedules.

Are older hazardous and harmful drinkers less likely to participate in health-related behaviors and practices as compared with nonhazardous drinkers?

OBJECTIVES: To describe the (1) prevalence of at-risk drinking and participation in health-related behaviors and practices and (2) associations of at-risk drinking with other health-related behaviors and practices among older persons completing a health-risk appraisal for the elderly (HRA-E). DESIGN: Cross-sectional study using data from a self-administered, mailed survey sample. SETTINGS: Persons from three organizations were surveyed: (1) the American Association of Retired Persons; and (2) a large medical group and (3) a community-based senior health center in southern California. PARTICIPANTS: 1,889 persons age 55 years and older. MEASUREMENTS: The HRA-E included items on health characteristics, drinking behaviors (including amount of alcohol use and two alcoholism screening measures: the CAGE (Cut down, Annoyed, Guilty, Eye opener) and Short Michigan Alcoholism Screening Test-Geriatric version (SMAST-G), and participation in selected health-related behaviors and practices. Social drinkers were defined as those who drank fewer than 14 drinks weekly and screened negative on the CAGE (defined as two or more "no" responses) and SMAST-G. Hazardous drinkers drank fewer than 14 drinks weekly and screened negative. Harmful drinkers drank fewer than 14 drinks weekly and screened positive. Possible at-risk drinkers drank 14 or more drinks weekly and screened positive. Least squares regression models were used to assess the effects of hazardous, harmful, and possible at-risk drinking on each of the health-related practices and behaviors. We also conducted these analyses using three other definitions of social, possible at-risk, hazardous, and harmful drinking. RESULTS: Of all respondents, 40% were social drinkers, 3% were harmful drinkers, 2% were hazardous drinkers, and 11% were possible at-risk drinkers. Hazardous, harmful, and possible at-risk drinkers commonly reported driving after drinking or being driven by someone who had been drinking (67%, 76%, and 64% respectively). Harmful and possible at-risk drinkers were more likely than social drinkers to smoke and were less likely to use seatbelts regularly. These findings were observed regardless of how the drinking groups were defined. CONCLUSION: All groups of at-risk drinkers more commonly engaged in selected adverse health-related behaviors and practices than did social drinkers.

Feasibility of using an alcohol-screening and health education system with older primary care patients.

BACKGROUND: This study evaluated the feasibility of a combined alcohol-screening and health education system for elderly patients METHODS: The Computerized Alcohol-Related Problems Survey (CARPS) was evaluated in primary care practices among 106 current drinkers, 60 years and older. The CARPS contains (1) a self-administered screening survey; (2) software to scan or hand-enter survey responses; (3) software to process data and electronically generate reports of patients' drinking risks; (4) health education; and (5) a database useful for clinical and quality improvement purposes. RESULTS: Nearly all study participants were able to complete the CARPS while waiting for a prescheduled appointment with their physician. There were 44% of patients who were hazardous and 9% who were harmful drinkers. About 20% of men and 26% of women were binge drinkers. Most (85%) patients agreed that alcohol is an important topic, 67% reported learning new information, 78% had never discussed drinking with a physician, and 31% intended to do so. After reviewing CARPS data, physicians concluded that alcohol use in the elderly is an important quality improvement topic. CONCLUSIONS: Combined screening and health education systems appear feasible for use in practice if they deal with pertinent health problems such as alcohol use. Their data can encourage discussions between physicians and patients and might be used for quality improvement activities.

Relationship between body mass index and activity in hip or knee arthroplasty patients.

The weight of patients has not been demonstrated to have a consistent effect on the rate of polyethylene wear in clinical studies of total joint replacement. For this reason, we analyzed the relationship between quantitative activity, measured with a pedometer, and body mass index, a measure of obesity. Data were acquired for 209 individuals, 22-82 years of age; all were independent community walkers. One hundred and fifty-one had a well functioning total hip or knee replacement. Analysis of variance was used to evaluate the relationship between activity and body mass index, with adjustments for confounding variables. The 58 individuals with no total joint prosthesis averaged 7,781 steps per day, which was higher (p < 0.01) than those with a total hip (5,869 steps per day) or knee (4,597 steps per day) replacement. The subjects with no total joint prosthesis were, however, younger than the patients with a prosthesis (p < 0.01), and the body mass index of the patients with a total knee replacement was higher than that of the patients with a hip replacement and that of the subjects with no prosthesis (p < 0.01). After adjustment for differences in age, gender, and Charnley class, a higher body mass index (greater obesity) was associated with lower activity (p = 0.05). With regard to the rate of polyethylene wear, decreased ambulatory activity may counterbalance increased weight, which could, at least in part, explain why weight has not had a consistent effect on polyethylene wear in clinical studies. Wear is a function of use, not time. The effect of obesity on activity should be considered in radiographic studies of wear and other outcome assessments of total joint replacements.

The choose-short effect and trace models of timing.

The tuned-trace multiple-time-scale (MTS) theory of timing can account both for the puzzling choose-short effect in time-discrimination experiments and for the complementary choose-long effect. But it cannot easily explain why the choose-short effect seems to disappear when the intertrial and recall intervals are signaled by different stimuli. Do differential stimuli actually abolish the effect, or merely improve memory? If the latter, there are ways in which an expanded MTS theory might explain differential-context effects in terms of reduced interference. If the former, there are observational and experimental ways to determine whether differential context favors prospective encoding or some other nontemporal discrimination.

Time and memory: towards a pacemaker-free theory of interval timing.

A popular view of interval timing in animals is that it is driven by a discrete pacemaker-accumulator mechanism that yields a linear scale for encoded time. But these mechanisms are fundamentally at odds with the Weber law property of interval timing, and experiments that support linear encoded time can be interpreted in other ways. We argue that the dominant pacemaker-accumulator theory, scalar expectancy theory (SET), fails to explain some basic properties of operant behavior on interval-timing procedures and can only accommodate a number of discrepancies by modifications and elaborations that raise questions about the entire theory. We propose an alternative that is based on principles of memory dynamics derived from the multiple-time-scale (MTS) model of habituation. The MTS timing model can account for data from a wide variety of time-related experiments: proportional and Weber law temporal discrimination, transient as well as persistent effects of reinforcement omission and reinforcement magnitude, bisection, the discrimination of relative as well as absolute duration, and the choose-short effect and its analogue in number-discrimination experiments. Resemblances between timing and counting are an automatic consequence of the model. We also argue that the transient and persistent effects of drugs on time estimates can be interpreted as well within MTS theory as in SET. Recent real-time physiological data conform in surprising detail to the assumptions of the MTS habituation model. Comparisons between the two views suggest a number of novel experiments.

Interval schedule performance in the goldfish Carassius auratus.

In experiment 1, five goldfish (Carassius auratus) paddle-pressed on fixed-interval (FI) and variable-interval (VI) schedules for food pellet reinforcement. The order of conditions was FI 60 s, FI 240 s, FI 30 s, FI 60 s, and VI 60 s. FI responding showed a scalloped pattern and response-rate break points were proportional to interval duration. Post-food wait times varied with interval duration, but were not proportional. Response rate on VI was constant. Experiment 2 studied the properties of food reinforcement as a time marker. The same five fish were presented an FI 60 s schedule of reinforcement with 25% of intervals ending in non-reinforcement (N). The fish responded faster and paused less following the omission stimulus (omission effect) and response rate was flat or declined through post-N intervals.

Temporal control in rats: analysis of nonlocalized effects from short interfood intervals.

The present experiment analyzed temporal control of postreinforcement pause duration during within-session changes in the criterion for reinforcement (interfood interval, IFI). Analysis of interval-by-interval changes in the pause revealed localized and nonlocalized effects from short intervals that caused specific changes in performance. In Phase 1, rats were presented with five consecutive 15-s IFIs intercalated into a series of 60-s IFIs. The 15-s set decreased the pause in adjacent and more remote 60-s intervals. In Phase 2, two sets of 15-s intervals were intercalated. The spacing between the two sets varied so that 0, 5, 10, or 15 60-s IFIs separated the sets. The postreinforcement pause tracked all changes in the IFI duration, and the localized effect from a short set extended beyond the next interval to the next few 60-s IFIs. Effects from one set, however, did not combine with a second set: Changes in the pause after two sets were the same regardless of the spacing between sets.

Development of a health risk appraisal for the elderly (HRA-E).

The purpose of this project is to develop a health risk appraisal for the elderly (HRA-E) and test its application in both medical and nonmedical settings. The HRA-E system consists of a questionnaire and software for computer-generation of personalized reports to participants, 55 years and older, and their physicians. Items in the questionnaire cover a comprehensive range of content domains relevant to health promotion in the elderly. The goal of the HRA-E system is to prevent functional decline. Samples of eligible subjects from the American Association of Retired Persons (AARP), a group practice, and a senior center were extended invitations to participate. Those responding affirmatively to the invitation were given a questionnaire and evaluation form. Each person who returned the questionnaire received his or her personal report and a second evaluation form. Four months after receiving their reports, respondents were questioned about behavior changes during the interim. Preliminary findings, based on 1895 respondents, indicate that nearly all participants found the questionnaire easy to complete and were pleased with its overall length. In addition, most participants read their reports, and many planned to take action, based on report recommendations. In the next phase of this project, the intent is to refine the questionnaire, extend the intervention protocols for longitudinal application, and evaluate its impact on health-related behaviors, medical care utilization, and functional decline.

Dynamics of temporal control in rats: the effects of a brief transition in interval duration.

Five rats lever-pressed for liquid reinforcers delivered according to a fixed-interval (FI) reinforcement schedule, where the interval requirement changed at an unpredictable point within a session. In a short square wave (SSW) condition, eight 30-s intervals were intercalated in a series of 120-s intervals so that the intervals changed from 120 to 30 s then back to 120 s. In a long square wave (LSW) condition the intervals changed from 120 to 480 s then back to 120 s. We observed rapid temporal control of post-reinforcement wait time duration by the IFI duration in the SSW condition only: Wait times decreased significantly during a transition to shorter (30 s) intervals; whereas wait times did not reliably increase during a transition to longer (480 s) intervals. Furthermore, in the SSW condition, wait time in post-transition intervals was shorter than that observed during pre-transition intervals. The results show that rats' wait times are sensitive to moment-to-moment changes in interval duration and that the dynamics depend on the direction in which the intervals change.

Continuous-processing--related event-related potentials in children with attention deficit hyperactivity disorder.

Visual information processing in children with attention deficit hyperactivity disorder (ADHD) was studied using event-related potentials recorded during two versions of the Continuous Performance Task (CPT). ADHD children made more errors, and had longer reaction times than normal children on both the single- and dual-target CPT. Event-related potential waveforms were normal in the ADHD children with reference to early processing stages, i.e., contingent negative variation, P1-N1 laterality, and processing negativities, suggesting that ADHD children did not differ in their level of preparedness or their ability to mobilize resources for target identification and categorization. With respect to later processing, P3 amplitude was reduced in the ADHD group, whereas P3 latency was longer than normal. ADHD children had a diminished late frontal negative component, suggestive of reduced involvement in postdecisional processing.

Multiple time scales in simple habituation.

Habituation is the waning of a reflex response to repeated stimulation. Habituation to closely spaced stimuli is faster and more complete than to widely spaced stimuli, but recovery is also more rapid (rate sensitivity). We show that a 2-unit, cascaded-integrator dynamic model can explain in detail an extensive data set on rate-sensitive habituation in the nematode Caenorhabditis elegans. Many apparently complex properties of habituation and learning dynamics may reflect interactions among a small number of processes with different time scales.