Search

Introduction/aims: Anecdotally, patients with facioscapulohumeral muscular dystrophy (FSHD) describe gastrointestinal (GI) and genitourinary (GU) symptoms. We explored the prevalence of GI and GU symptoms and their impact on quality of life (QOL) in people with FSHD compared to healthy household controls., Methods: In this descriptive, cross-sectional study, we emailed a survey exploring GI and GU symptoms to all FSHD Society patient contacts (n = 3507). We invited those with FSHD and unaffected household controls to respond. Non-parametric statistics were used to compare symptom frequency and impact of symptoms between respondents with FSHD and household controls. Within the FSHD group, symptom frequency was assessed relative to measures of disease progression (need for ambulatory or respiratory support)., Results: Surveys from 701 respondents (652 with FSHD) ≥18 years old were included in analysis. Those with FSHD had symptoms affecting both GI and GU systems more frequently than controls using ordinal rating of symptom frequency. Within the FSHD group, more advanced disease was associated with increased symptom frequency. QOL was negatively impacted by the GI and GU symptoms. There was no difference between groups in use of medications to treat these symptoms., Discussion: Recognition and treatment of GI and GU symptoms in people with FSHD, particularly those with more advanced disease, could improve QOL. Additional investigation is required to confirm these findings and understand the physiology., (© 2023 The Authors. Muscle & Nerve published by Wiley Periodicals LLC.)

Diving is central to the foraging strategies of many marine mammals and seabirds. Still, the effect of dive depth on foraging cost remains elusive because energy expenditure is difficult to measure at fine temporal scales in wild animals. We used depth and acceleration data from eight lactating California sea lions (Zalophus californianus) to model body density and investigate the effect of dive depth and tissue density on rates of energy expenditure. We calculated body density in 5 s intervals from the rate of gliding descent. We modeled body density across depth in each dive, revealing high tissue densities and diving lung volumes (DLVs). DLV increased with dive depth in four individuals. We used the buoyancy calculated from dive-specific body-density models and drag calculated from swim speed to estimate metabolic power and cost of transport in 5 s intervals during descents and ascents. Deeper dives required greater mean power for round-trip vertical transit, especially in individuals with higher tissue density. These trends likely follow from increased mean swim speed and buoyant hinderance that increasingly outweighs buoyant aid in deeper dives. This suggests that deep diving is either a 'high-cost, high-reward' strategy or an energetically expensive option to access prey when prey in shallow waters are limited, and that poor body condition may increase the energetic costs of deep diving. These results add to our mechanistic understanding of how foraging strategy and body condition affect energy expenditure in wild breath-hold divers., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Objective: The purpose of this descriptive study was to evaluate the presence of telehealth content on chiropractic state board websites compared with websites from the medical and physical therapy professions during the early COVID-19 pandemic., Methods: State board websites for chiropractic, medicine, and physical therapy for each of the 50 United States and the District of Columbia were searched for the word "tele" to determine if there was a link on the homepage for content related to telehealth guidance. If there was none, the homepage was queried for the word "COVID" to determine if there was a link for COVID-19-related guidance. If yes, that linked COVID-19 page was queried for the word "tele." Consensus of 4 of 5 reviewers was sought. Binary results were entered into a separate spreadsheet for each profession (telehealth content easily accessible, yes or no). Easily accessible was defined as information found within 1 or 2 clicks. This search was performed between January 1, 2021, and March 1, 2021., Results: There were 11 of 51 (21%) chiropractic state board websites that provided content regarding telehealth on the main page, 8 of 51 (16%) provided content on a separate COVID-19-related page, and 32 of 51 (63%) did not provide content that was accessible within 1 or 2 clicks. Comparatively, 9 of 51 (18%) medical state board websites provided content regarding telehealth on the main page, 20 of 51 (39%) provided content on a COVID-19-related page, and 22 of 51 (43%) did not provide content that was accessible within 1 or 2 clicks. Lastly, 10 of 51 (20%) physical therapy state board websites provided content regarding telehealth on the main page, 19 of 51 (37%) provided content on a COVID-19-related page, and 22 of 51 (43%) did not provide content that was accessible within 1 or 2 clicks., Conclusion: Telehealth content was more readily available on medical and physical therapy state board websites compared with chiropractic state board websites in the early stages of the COVID-19 pandemic., (© 2022 by National University of Health Sciences.)

Plant-based beverage consumption is increasing markedly. Value-added dehulled rice ( Oryza sativa ) germination was investigated to improve beverage qualities. Germinating brown rice has been shown to increase health-promoting compounds. Utilizing green processing, wholesome constituents, including bran, vitamins, minerals, oils, fiber and proteins should should convey forward into germinated brown rice beverages. Rapid visco-analyzer (RVA) data and trends established that brown rice, preheated brown rice and germinated brown rice had higher pasting temperatures than white rice. As pasting temperature in similar samples may be related to gelatinization, RVA helped guide the free-flowing processing protocol using temperatures slightly above those previously reported for Rondo gelatinization. Particle size analysis and viscometric evaluations indicate that the developed sprouted brown rice beverage is on track to have properties close to commercial samples, even though the sprouted brown rice beverage developed has no additives, fortifications, added oils or salts. Phenolics and γ-aminobutyric acid increased slightly in germinated brown rice, however, increases were not maintained throughout most stages of processing. Significantly lower inorganic arsenic levels (113 ng/g) were found in germinated (sprouted) brown rice, compared to Rondo white and brown rice, which is far below the USA threshold level of 200 ng/g.

Adherence to therapy for pulmonary arterial hypertension is essential to optimize patient outcomes, but data on real-world adherence to different pulmonary arterial hypertension drug classes are limited. This retrospective database analysis evaluated relationships between adherence, hospitalization, and healthcare costs in pulmonary arterial hypertension patients treated with endothelin receptor antagonists or phosphodiesterase type-5 inhibitors. From the IQVIA Adjudicated Health Plan Database, patients with pulmonary arterial hypertension were identified based on diagnostic codes and prescriptions for endothelin receptor antagonists (ambrisentan, bosentan, macitentan) or phosphodiesterase type-5 inhibitors (sildenafil, tadalafil) approved for pulmonary arterial hypertension. Patients were assigned to the class of their most recently initiated (index) pulmonary arterial hypertension therapy between 1 January 2009 and 30 June 2015. Medication adherence was measured by proportion of days covered; patients with proportion of days covered ≥80% were considered adherent. The proportion of adherent patients was higher for endothelin receptor antagonists (571/755; 75.6%) than for phosphodiesterase type-5 inhibitors (970/1578; 61.5%; P  < 0.0001). In both groups, hospitalizations declined as proportion of days covered increased. Among adherent patients, those on endothelin receptor antagonists had a significantly lower hospitalization rate than those on phosphodiesterase type-5 inhibitors (23.1% versus 28.5%, P  = 0. 0218), fewer hospitalizations (mean (standard deviation) 0.4 (0.8) versus 0.5 (0.9); P  = 0.02), and mean hospitalization costs during the six-month post-index ($9510 versus $15,726, P  = 0.0318). Increasing adherence reduced hospitalization risk more for endothelin receptor antagonists than for phosphodiesterase type-5 inhibitors (hazard ratio 0.176 versus 0.549, P  = 0.001). Rates and numbers of rehospitalizations within 30 days post-discharge were similar between groups. Mean total costs were higher with endothelin receptor antagonists than phosphodiesterase type-5 inhibitors in all patients ($91,328 versus $72,401, P  = 0.0003) and in adherent patients ($88,867 versus $56,300, P  < 0.0001), driven by higher drug costs., (© The Author(s) 2020.)

There is abundant evidence that domestic dogs (Canis familiaris) readily follow pointing and other cues given by humans. But there has been much less research into the question of whether dogs can learn to discriminate between different humans giving repeated honest or dishonest cues as to food location, by ignoring the information imparted by the deceiver. Prior research has demonstrated that even after repeated exposures to deceptive cues with respect to food location, dogs failed to learn to ignore those cues completely. Kundey, De Los Reyes, Arbuthnot, Coshun, Molina, and Royer (2010) found the same outcome in a similar experiment. The purpose of the current experiment was to determine if dogs could learn to discriminate between an honest and a deceptive human by ignoring the deceiver's cues even when it was obvious that the container being pointed at was not baited by using two transparent containers. Eight dogs were tested. On 20 cooperator trials, the experimenter stood behind the baited container and cued the dog, located midway between the containers and 3 m away, to approach it. On 20 deceiver trials, a different experimenter stood behind the empty container and cued the dog to approach that container. Results replicated prior research in that, even though the containers were transparent, the dogs failed to learn to distrust the deceiver completely and went to the empty and indicated container on more than half of the deceiver trials.

Objective: Burn-related immunosuppression can promote human herpesviridae infections. However, the effect of these infections on morbidity and mortality after pediatric burn injuries is unclear., Methods: We retrospectively analyzed pediatric patients with burns ≥10% of the total body surface area (TBSA) who were admitted between 2010 and 2015. On clinical suspicion of a viral infection, antiviral therapy was initiated. Viral infection was confirmed via Tzanck smear, viral culture, and/or PCR. Study endpoints were mortality, days of antiviral agent administration, type of viral test used, type of viral infection, and length of hospitalization., Results: Of the 613 patients were analyzed, 28 presented with clinically diagnosed viral infections. The use of Tzanck smears decreased over the past 5 years, whereas PCR and viral cultures have become standard. Patients with viral infections had significantly larger burns (53±15% vs. 38±18%, p<0.001); however, length of stay per TBSA burn was comparable (0.5±0.4 vs. 0.6±0.2, p=0.211). The most commonly detected herpesviridae was herpes simplex virus 1. Two patients died due to sepsis, which was accompanied by HSV infection. The mortality rate among all patients (2.7%) was comparable to that in the infected group (7.1%, p=0.898). Acyclovir was given systemically for 9±8days (N=76) and/or topically for 9±9days for HSV (N=39, combination of both N=33). Ganciclovir was prescribed in three cases for CMV., Conclusions: Viral infections occur more commonly in patients suffering from larger burns, and HSV infections can contribute to mortality., (Copyright © 2017 Elsevier Ltd and ISBI. All rights reserved.)

A rapid research method using microwave-assisted probe ultrasonication was developed to quantify total, insoluble, and soluble starch in various sugar crop products. Several variables affecting starch solubilisation were evaluated, (1) heating method, (2) boiling time, (3) probe ultrasonication time, (4) water loss, (5) concentration, (6) sample colour, and (7) sample. The optimised method solubilises < 40,000 ppm insoluble starch with microwave-assisted sonication in 6 min, has acceptable precision (<6% CV), accuracy (⩾ 95%), uses a corn starch reference, and incorporates a colour blank to remove contribution from natural colourants found in industrial samples. This method was validated using factory samples and found applicable to sugarcane and sweet sorghum bagasse (3% CV), mixed juices (2%), massecuites (4%), molasses (7%), and raw sugars (12%), 100% satisfactory performance z-scores were also obtained. Total starch values obtained with this method were significantly higher than those measured using other methods presently accepted by the sugar industry., (Published by Elsevier Ltd.)

The emergence of multi-drug-resistant bacteria, coupled with the lack of new antibiotics in development, is fast evolving into a global crisis. New strategies utilizing existing antibacterial agents are urgently needed. We propose one such strategy in which four outmoded β-lactam antibiotics (ampicillin, carbenicillin, cephalothin and oxacillin) and a well-known antiseptic (chlorhexidine di-acetate) were fashioned into a group of uniform materials based on organic salts (GUMBOS) as an alternative to conventional combination drug dosing strategies. The antibacterial activity of precursor ions (e.g., chlorhexidine diacetate and β-lactam antibiotics), GUMBOS and their unreacted mixtures were studied with 25 clinical isolates with varying antibiotic resistance using a micro-broth dilution method. Acute cytotoxicity and therapeutic indices were determined using fibroblasts, endothelial and cervical cell lines. Intestinal permeability was predicted using a parallel artificial membrane permeability assay. GUMBOS formed from ineffective β-lactam antibiotics and cytotoxic chlorhexidine diacetate exhibited unique pharmacological properties and profound antibacterial activity at lower concentrations than the unreacted mixture of precursor ions at equivalent stoichiometry. Reduced cytotoxicity to invasive cell types commonly found in superficial and chronic wounds was also observed using GUMBOS. GUMBOS show promise as an alternative combination drug strategy for treating wound infections caused by drug-resistant bacteria.

In sugarcane processing, starch is considered an impurity that negatively affects processing and reduces the quality of the sugar end-product. In the last decade, there has been a general world-wide increase in starch concentrations in sugarcane. Industrial α-amylases have been used for many years to mitigate issues arising from starch in the sugarcane industry. Mixed results have prompted further studies of the behaviour of different physical forms of starch and their interactions with α-amylases during processing. By using corn starch as a reference in model juices and syrups, processing parameters, activities, and hydrolysis of insoluble, swollen, and soluble starch forms were evaluated for two commercial α-amylases with high (HT) and intermediate (IT) temperature stability, respectively. The ability of starch to solubilise across a sugarcane factory is largely limited by increased Brix values. Optimum target locations and conditions for the application of α-amylases in sugarcane processing are discussed in detail., (Published by Elsevier Ltd.)

Objectives: Reduction in faecal shedding of Shiga toxin-producing enterohaemorrhagic Escherichia coli (EHEC) in food-producing animals is a viable strategy to minimize human disease initiated by exposure to these microorganisms. To this end, an intervention strategy involving the electrostatic hybridization of two commonly used anti-infective agents for veterinary practice (i.e. chlorhexidine and ampicillin) was evaluated to curtail EHEC-transmitted disease from ruminant sources. Chlorhexidine di-ampicillin is a novel group of uniform material based on organic salts (GUMBOS) with inherent in vitro antibacterial activity that comes from its parent antimicrobial ions, chlorhexidine and ampicillin., Methods: Antibacterial activities for chlorhexidine diacetate, sodium ampicillin, chlorhexidine di-ampicillin and stoichiometrically equivalent 1 : 2 chlorhexidine diacetate : sodium ampicillin were assessed using the serial 2-fold dilution method and time-kill studies against seven isolates of E. coli O157:H7 and one non-pathogenic E. coli 25922. Further studies to investigate synergistic interactions of reacted and stoichiometrically equivalent unreacted antimicrobial agents at MICs and possible mechanisms were also investigated., Results: Synergism and in vitro antibacterial activities against EHEC were observed in this study, which suggests chlorhexidine di-ampicillin could be a useful reagent in reducing EHEC transmission and minimizing EHEC-associated infections. Likewise, chlorhexidine di-ampicillin reduced HeLa cell toxicity as compared with chlorhexidine diacetate or the stoichiometric combination of antimicrobial agents. Further results suggest that the mechanisms of action of chlorhexidine di-ampicillin and chlorhexidine diacetate against E. coli O157:H7 are similar., Conclusions: Reacting antimicrobial GUMBOS as indicated in this study may enhance the approach to current combination drug therapeutic strategies for EHEC disease control and prevention.

Purpose: The purpose of this study is to evaluate the effectiveness of a nutrition-based shared medical appointment (SMA) intervention in the treatment of prediabetes compared to the individualized counseling standard of care., Methods: A randomized controlled trial design comparing health outcomes in patients with prediabetes attending either an individualized counseling (control group) or three 90-minute nutrition SMA (intervention group) sessions. Demographic, anthropometric (weight and body mass index), clinical (blood pressure), and biochemical (lipid profile, fasting blood sugar, glycated hemoglobin, albumin-to-creatinine ratio) measures were obtained from all participants at baseline, at 3 months, and at 1 year., Results: Ninety-four participants were randomized into the 2 study groups with a 69% completion rate at 1 year (n = 34 SMA, n = 31 control). The average participant was Caucasian (64%), male (54%), 58.3 ± 9.6 years, had a BMI of 30.8 ± 4.9 kg/m(2) (obese), and fasting blood glucose of 109 ± 9.5 mg/dL. The SMA and control participants lost a mean of 6.6 pounds and 3.6 pound, respectively; neither group met the 5% modest weight loss expected. The SMA and control group experienced a mean drop in fasting blood glucose of 6 mg/dL., Conclusions: As demands on health care providers continue to rise, finding innovative ways to manage the patient load while providing quality health care is increasingly important. SMA health outcomes were equivalent to individual counseling outcomes, while increasing the provider's productivity by treating 6 to 8 people with prediabetes in 90 minutes compared to 1 patient in 60 minutes.

Objectives: Intermittent bolus propofol is an effective agent for pediatric magnetic resonance imaging sedation but requires constant vigilance and dose titration. Magnetic resonance imaging-compatible infusion pumps may make it possible to continuously infuse propofol, achieving a steady level of sedation at a lower total dose. This study investigates total propofol dose, recovery time, and magnetic resonance image quality in children receiving intermittent vs. continuously infused propofol sedation in children undergoing brain and spine magnetic resonance imaging studies., Design: An open-label, prospective, randomized, controlled study. A single-blinded radiologist rated the quality of magnetic resonance images., Setting: Children's hospital pediatric radiology sedation center., Patients: One hundred seventy children age 1 month to 18 yrs undergoing deep sedation for brain, spine, or both brain and spine magnetic resonance imaging., Interventions: After informed consent, patients were randomly assigned to two groups: group 1 (intermittent) received a propofol bolus of 2-4 mg/kg, followed by repeat boluses of 0.5-2 mg/kg/dose as needed. Group C (continuous) received a bolus of propofol 2-4 mg/kg, followed by a continuous infusion of 100 μg/kg/min with 1-mg/kg/dose boluses with drip titration to effect., Measurements and Main Results: Patient demographics, sedation risk assessment, propofol dose, sedation recovery times, incidence of complications, and quality of the magnetic resonance imaging studies were measured. A total of 170 children were enrolled in the study, with 75 in group C and 95 in group I. Both groups were similar with regard to age, weight, gender, and magnetic resonance imaging study type. Group C required a lesser dose of propofol (132 ± 54 μg/kg/min) compared to (162 ± 74 μg/kg/min) in that required in group I (p = .018). There were no differences between the two groups with regard to quality of the imaging study, recovery time, or incidence of complications., Conclusions: Compared to intermittent bolus dosing, continuous propofol infusion provides lesser dose exposure without impacting recovery time or quality of the magnetic resonance imaging study.

We herein report the preparation and investigation of antibacterial activity of biocidal ionic liquids (ILs) consisting of cationic imidazolium or pyridinium and an anionic β-lactam antibiotic. The antibacterial properties were quantified by measuring the minimum inhibitory concentration and minimum bactericidal concentration against Escherichia coli O157:H7, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecium. In general, the ILs had improved antibacterial activity than their parent materials, whether individually or in combination. In 83% of the experiments, the ampicillin ILs (Amp-ILs) had better antibacterial activities than their quaternary halide parent materials, whereas in 92% of the experiments, Amp-ILs outperformed the commercially available sodium ampicillin salt. Amp-ILs had up to 43 times improved antibacterial activity than sodium ampicillin. Overall, when normalized for ampicillin content, ILs had greater antimicrobial activity against E. coli O157:H7, K. pneumoniae, S. aureus, and E. faecium than sodium ampicillin alone., (© 2011 John Wiley & Sons A/S.)

Objective: Megestrol acetate (MA) has been used to treat weight loss in pediatric patients with malignancies, cystic fibrosis and HIV/AIDS. We herein report our experience with MA in pediatric patients with chronic kidney disease (CKD)., Design: We conducted a retrospective cohort study. Charts were evaluated for clinical, treatment, and laboratory data at six time points: approximately 6 months prior to initiation of MA, at initiation and cessation of MA, and at 2-, 4-, and 8-month follow-up. Anthropometric measurements were corrected for age and sex by conversion to z scores., Setting: Division of Pediatric Nephrology, Helen DeVos Children's Hospital, Grand Rapids, MI., Patients: Pediatric patients (n = 25) with CKD and poor weight gain., Intervention: Patients were administered MA at initial and tapered doses of 14.4 ± 8.1 mg/kg/d and 10.1 ± 6.5 mg/kg/d, respectively, for 5.4 ± 6.3 months., Results: The study population (n = 25) was 60% male, 16% African American, 72% white, and 12% Hispanic with a mean ± SD age of 8.9 ± 5.4 years. Prior to MA therapy, patients demonstrated a decrease in BMI and poor weight gain. The treatment phase was associated with significant increases in BMI (P < .0001) and weight (P < .0001), which were well sustained at 8-month follow-up (P < 0.01 and P < 0.001, respectively). Patients demonstrated continued increases in height. A single patient exhibited physical adverse side effects (cushingoid features) associated with MA; otherwise, MA was well tolerated., Conclusions: MA appears to effectively improve weight gain in pediatric CKD patients with minimal adverse side effects and may therefore serve as a safe, short-term, nutritional strategy., (Copyright © 2010 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

In previous research designed to test whether place learning or response learning proceeds more quickly and better in rats, place has not been defined unambiguously when direction has been controlled by moving an apparatus around in the test room (Blodgett, McCutchan, & Mathews, 1949; Skinner et al., 2003). In Experiment 1, we compared place and response learning while controlling direction in a static apparatus, thus making the meaning of place unambiguous. The performance of rats that had to make different turns to find food in a particular place and rats that had to always make the same turn to find food in two different places did not differ. In Experiment 2, visual cues were made equally discriminable for place and response learners in a static apparatus. Place learners still failed to outperform response learners, but there was evidence that response biases interfered more with place than with response learning. The results are discussed with reference to the historical debate that generated the original research and also in terms of morecontemporary spatial-learning issues in rats.

In Experiment 1, rats foraged for food in six successive phases with 8, 16, 24, 32, 40, and 48 arms attached in random locations to a large radial maze. The percentage of novel choices appeared to be determined more by spatial proximity than by number of arms. In Experiment 2, rats foraged for food in four successive phases with 8, 16, 24, and 48 arms attached to the maze in spread-out or tight configurations. Performance was poor in the tight configurations regardless of the number of arms. Performance was excellent in the 8-arm spread-out condition but declined as 16 and, then again, 24 arms were added. Thus, spatial separation, not number of locations, was the chief determinant of performance in the first two experiments. In Experiment 3, in successive phases, 8, 16, 24, 32, 40, 48, 16, and 8 food towers were set in a circle on the floor, with the spatial separation between adjacent towers held constant at 33 cm. The percentage of novel choices declined as 8 towers became 16 and did not change again with 24, 32, 40, or 48 towers in place but then increased again as 16 towers became 8. In Experiment 4, in successive phases, 8, 16, 24, and 32 food towers were set in a circle, with the spatial separation between adjacent towers held constant at 66 cm. The percentage of novel choices declined as 8 towers became 16 and again as 16 towers became 24 but did not decline further. These data were discussed in terms of the fundamental problems posed by variations in the number of food locations in the pursuit of the limit of spatial memory in rats.

Tell rats were given extended lever-press training on a fixed-interval (FI) 30-s food reinforcement schedule from the outset or following exposure to one or two previous reinforcement schedules. For 4 rats the previots schedule was either fixed-ratio 20, which generated high response rates, or differential-reinforcement-of-low-rate 20 s, which produced low response rates. For 4 additional rats the extended training on FI 30 s was preceded by experience with two schedules: fixed-ratio 20 followed by differential-reinforcement-of-low-rate 20 s; or the same two schedules in the reverse order. Fixed-interval response rates were initially affected by the immediately preceding schedule, but after 80 to 100 sessions, all traces of prior schedule history had disappeared. The results also showed no long-term effect of schedule history on the interfood-interval patterns of responding on the FI 30-s schedule. These results support one of the most central tenets of the experimental analysis of behavior: control by the immediate consequences of behavior.

In Experiment 1, a variable-ratio 10 schedule became, successively, a variable-interval schedule with only the minimum interreinforcement intervals yoked to the variable ratio, or a variable-interval schedule with both interreinforcement intervals and reinforced interresponse times yoked to the variable ratio. Response rates in the variable-interval schedule with both interreinforcement interval and reinforced interresponse time yoking fell between the higher rates maintained by the variable-ratio schedule and the lower rates maintained by the variable-interval schedule with only interreinforcement interval yoking. In Experiment 2, a tandem variable-interval 15-s variable-ratio 5 schedule became a yoked tandem variable-ratio 5 variable-interval x-s schedule, and a tandem variable-interval 30-s variable-ratio 10 schedule became a yoked tandem variable-ratio 10 variable-interval x-s schedule. In the yoked tandem schedules, the minimum interreinforcement intervals in the variable-interval components were those that equated overall interreinforcement times in the two phases. Response rates did not decline in the yoked schedules even when the reinforced interresponse times became longer. Experiment 1 suggests that both reinforced interresponse times and response rate-reinforcement rate correlations determine response-rate differences in variable-ratio 10 and yoked variable-interval schedules in rats. Experiment 2 suggests a minimal role for the reinforced interresponse time in determining response rates on tandem variable-interval 30-s variable-ratio 10 and yoked tandem variable-ratio 10 variable-interval x-s schedules in rats.

In the first of four experiments, rats were exposed to a modified multiple continuous reinforcement-extinction schedule during 15-min daily sessions. In one condition (saves condition) with the cuelight on, a single lever press produced a food pellet, briefly extinguished the cuelight, and started a clock. Saves (additional lever presses with interresponse times less than 1 s) produced an additional food pellet, briefly extinguished the cuelight, and restarted the interresponse time clock. The cuelight was extinguished 1 s after the last lever press and remained off during a 10-s period of extinction, during which no food pellets were delivered. In the other condition (savings account condition), the contingencies were the same except that the cuelight was extinguished and was not reilluminated after the initial lever press, and the delivery of all food pellets in the reinforcement component was delayed until the onset of extinction. In both conditions, rats made saves, but mean saves (total saves divided by the number of reinforcement components) were slightly reduced in the savings account condition. In Experiment 2, using six equally spaced 15-min sessions per day on alternate days, saves were either followed immediately with food and brief cuelight offset (saves condition) or were not reinforced at all. Mean saves were much greater when saves were reinforced. In Experiment 3, during 5-min daily sessions, saves earned a single pellet (savings account condition) or a number of pellets equal to the ordinal number of the lever press (interest condition). Rats made fewer mean saves, with little change in the food rate, when saves earned interest. In Experiment 4, the rats earned all their food in the operant situation during 24 daily 5-min sessions, these separated by 55-min intersession intervals during which no food was available; otherwise, the conditions were the same as in Experiment 3. In Experiment 4, the shift to interest for saves led to an increase in mean daily mean saves (total daily mean saves divided by the number of daily sessions) as well as to an increase in the number of food pellets delivered in each session. The results are discussed in terms of self-control and behavioral economics.