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.

Continuous-processing related ERPS in schizophrenic and normal children.

The continuous performance task (CPT) has proven to be sensitive to schizophrenic impairments. Multichannel event-related potential (ERP) data were recorded from schizophrenic and normal children during performance of easy and hard versions of the CPT. Schizophrenics produced fewer hits, more false alarms, and prolonged reaction times. Poor performance in schizophrenics was associated with four ERP abnormalities: (1) Schizophrenics did not exhibit the normal increase in amplitude of an early-onset, processing-related negativity from nontarget to target stimuli, suggesting a failure to appropriately allocate attentional resources to discriminative processing. (2) Although P3 amplitude to targets was not significantly smaller in schizophrenic children, the distribution of P3 amplitude between target and nontarget responses in the easy and hard versions of the CPT was abnormal, suggesting that schizophrenics differed in the strategic allocation of resources in later stages of CPT processing. (3) In all task conditions schizophrenics showed a parietal negative component with a latency of 400 msec seen in younger, but not older normal children, suggestive of maturational lag. (4) ERP data demonstrated absence of right-lateralized P1/N1 amplitude in schizophrenic children. Taken together these data indicate that at several stages of information processing, schizophrenics are deficient in the control and strategic allocation of processing resources.

Event-related potential correlates of impaired attention in schizophrenic children.

Electrophysiological correlates of focused attention were studied in 13 schizophrenic and 19 age- and gender-matched children. Subjects performed a version of the Continuous Performance Task (CPT) in which a target was designated as any digit from 0 through 9 occurring on two successive stimulus presentations. Signal digits were surrounded by distractor digits which varied in position, value, and number. Event-related potentials (ERPs) elicited by each stimulus of a target pair were recorded from midline and homologous parietal, temporal, and occipital electrode placements. Schizophrenic children made significantly more errors of omission and commission than normal children. The amplitude and time course of the intertrial CNV was the same for both groups. There was a circumscribed amplitude asymmetry, left smaller than right, for the P1/N1 and P2 measures which was greater in normal than in schizophrenic children. The P3 component was significantly larger to the second stimulus of the target pair than to the first for both groups, and larger for the normal than the schizophrenic children to both stimuli.

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.

Event-related potentials in high-functioning adult autistics: linguistic and nonlinguistic visual information processing tasks.

Event-related potentials (ERPs) were recorded from high-functioning adult autistics and age- and IQ-matched normal controls during performance of two non-linguistic information processing tasks, the Continuous Performance Task (CPT) and Span of Apprehension (SPAN), and an Idiom Recognition Task (IRT) involving idiomatic, literal and nonsense phrases. The autistics exhibited behavioral deficits only when attempting to identify idiomatic phrases. The ERP correlate of that deficit was greatly reduced N400 to idioms. In addition, autistics produced larger N1 amplitudes in all tasks, and larger P3s in the IRT and CPT.

Cognitive function, mood and P3 latency: effects of the amelioration of anemia in dialysis patients.

Attention difficulties and psychomotor slowing associated with depressed mood affect the ability of individuals to perform on most neuropsychological tests. It has been suggested that latency of the P3 (P300) component of the event-related EEG potential is an index of neurocognitive status which is not affected by mood. Dialysis patients, who experience diminished dysphoric mood with the reversal of anemia when treated with recombinant human erythropoietin (rHuEPO), were tested for neurocognitive performance, mood and latency of P3. Prior to rHuEPO treatment mood was dysphoric, and neurocognitive testing showed mild deficits, but P3 latency was normal. After treatment, mood improved and neurocognitive test performance was normal. P3 amplitude increased over frontal areas, while P3 latency remained unchanged. Thus, in the case of dysphoric mood, P3 latency may provide a more accurate index of cognitive capacity (as opposed to level of functioning) than neurocognitive test measures.

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.

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.

Dynamics of time discrimination.

Pigeons tracked sinusoidal sequences of interfood intervals (IFIs) by pausing in each interval for a time proportional to the preceding interval. Schedules with either long (30-90 s) or short (5-15 s) values, with variable numbers of cycles and starting phase each day, were tracked about equally well. Tracking was apparently immediate and did not improve across sessions. Experiment 2, in which long and short series were presented on alternate days, showed that tracking on long was more impaired than on short. Experiment 3 showed that occasional presentation of a short IFI in a series of fixed, longer IFIs caused a reduction in waiting time in the next IFI. These effects are evidence for a fast-acting timing mechanism in which waiting time in the IFI N + 1 is strongly determined by the preceding IFI, N. Earlier IFIs have some cumulative effect, but the details remain to be elucidated.

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.

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.

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.

Behavioral contrast in rats when qualitatively different reinforcers are used.

Behavioral contrast was studied during multiple schedules which provided qualitatively different reinforcers in the two components. Five rats responded on a baseline schedule in which both components delivered food reinforcers (food-food), and then on a contrast schedule in which one component delivered food and the other delivered water (food-water). Following this, baseline was recovered. Five other rats responded on a baseline schedule in which both components delivered water reinforcers (water-water), then on a food-water schedule, and then on the baseline, water- water, schedule. Contrast was not observed when relatively low rates of reinforcement were use but it was sometimes observed when high rates of reinforcement were used. The rate of responding for a constant water reinforcer decreased when food replaced water in the other component. The rate of responding for a constant food reinforcer did not change when a water reinforcer replaced food in the other component. These results are similar to those reported by Ettinger and McSweeney (1981) when pigeons served as subjects.

Massed and spaced stimulus sequences in dimensional discrimination.

In two experiments, pigeons' responding to a visual flicker-rate continuum was established by a maintained generalization procedure. For both experiments, variable-interval reinforcement was available for responses during stimuli from one half of the stimulus continuum while responses during other stimuli were extinguished. The first experiment compared gradients of dimensional stimulus control produced by randomly presented positive and negative stimuli with gradients produced by massed positive and negative stimuli. The second experiment alternated the order of massed stimulus sequences. In both cases, massing of stimulus sequences diminished positive dimensional contrast effects, without seriously disturbing discrimination between positive and negative stimuli. The results indicate that stimulus sequences can have an important role in the production of dimensional contrast effects.

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.