Spatial dysregulation of T follicular helper cells impairs vaccine responses in aging.

The magnitude and quality of the germinal center (GC) response decline with age, resulting in poor vaccine-induced immunity in older individuals. A functional GC requires the co-ordination of multiple cell types across time and space, in particular across its two functionally distinct compartments: the light and dark zones. In aged mice, there is CXCR4-mediated mislocalization of T follicular helper (TFH) cells to the dark zone and a compressed network of follicular dendritic cells (FDCs) in the light zone. Here we show that TFH cell localization is critical for the quality of the antibody response and for the expansion of the FDC network upon immunization. The smaller GC and compressed FDC network in aged mice were corrected by provision of TFH cells that colocalize with FDCs using CXCR5. This demonstrates that the age-dependent defects in the GC response are reversible and shows that TFH cells support stromal cell responses to vaccines.

The Use of Immersive Virtual Reality in Sensory Sessions on a Specialist Dementia Unit: Service Evaluation of Feasibility and Acceptability.

This service evaluation reviewed inclusion of Immersive Virtual Reality (iVR) relaxation activities as part of routine occupational therapy sensory sessions on a specialist dementia unit. Twenty-five sessions were completed over 13 wk with 14 participants. Nine participants chose to engage in multiple sessions. Feasibility was assessed through participant engagement and tolerability. Modal first session length was in the range 30 s to 2 min. This increased to over 2 min on second sessions. There was a lack of significant adverse effects measured by direct questioning, neuropsychiatric assessment before vs. after sessions and adverse incident reporting. Acceptability was assessed via structured review of user and staff feedback which noted positive experiences such as relaxation, openness to discussion, reminiscence, wider engagement and interest in future use. Further work is required to explore efficacy and use in other settings.

Views on sharing mental health data for research purposes: qualitative analysis of interviews with people with mental illness.

BACKGROUND: Improving the ways in which routinely-collected mental health data are shared could facilitate substantial advances in research and treatment. However, this process should only be undertaken in partnership with those who provide such data. Despite relatively widespread investigation of public perspectives on health data sharing more generally, there is a lack of research on the views of people with mental illness. METHODS: Twelve people with lived experience of mental illness took part in semi-structured interviews via online video software. Participants had experience of a broad range of mental health conditions including anxiety, depression, schizophrenia, eating disorders and addiction. Interview questions sought to establish how participants felt about the use of routinely-collected health data for research purposes, covering different types of health data, what health data should be used for, and any concerns around its use. RESULTS: Thematic analysis identified four overarching themes: benefits of sharing mental health data, concerns about sharing mental health data, safeguards, and data types. Participants were clear that health data sharing should facilitate improved scientific knowledge and better treatments for mental illness. There were concerns that data misuse could become another way in which individuals and society discriminate against people with mental illness, for example through insurance premiums or employment decisions. Despite this there was a generally positive attitude to sharing mental health data as long as appropriate safeguards were in place. CONCLUSIONS: There was notable strength of feeling across participants that more should be done to reduce the suffering caused by mental illness, and that this could be partly facilitated by well-managed sharing of health data. The mental health research community could build on this generally positive attitude to mental health data sharing by following rigorous best practice tailored to the specific concerns of people with mental illness.

Integrating Patient Activation Into Dialysis Care.

Patient activation, the measure of patients' readiness and willingness to manage their own health care, is low among people receiving in-center hemodialysis, which is exacerbated because such centers are commonly set up for patients to passively receive care. In our pursuit of person-centered care and value-based medicine, enabling patients to take a more active role in their care can lead to healthy behaviors, with subsequent reductions in individual burden and costs to the health care system. To improve patient activation, we need to embrace a patient-first approach and combine it with ways to equip patients to thrive with self-management. This requires changes in the training of the health care team as well as changes in care delivery models, promoting interventions such as health coaching and peer mentoring, while leveraging technology to enable self-access to records, self-monitoring, and communication with providers. We also need health care policies that encourage a focus on patient-identified goals, including more attention to patient-reported outcomes. In this article, we review the current status of patient activation in dialysis patients, outline some of the available interventions, and propose steps to change the dynamics of the current system to move toward a more active role for patients in their care.

Tardive Seizures After Electroconvulsive Therapy.

OBJECTIVES: Seizures that occur spontaneously after termination of an electroconvulsive therapy (ECT) seizure are termed tardive seizures. They are thought to be a rare complication of ECT, influenced by risk factors that affect seizure threshold. However, there has been limited review of tardive seizures with modified ECT. We aimed to review the literature to provide clinical guidance for the use of ECT after tardive seizures. METHODS: PubMed, EMBASE, PsycInfo, and CINAHL databases were searched from inception to May 2021 to identify cases of modified ECT, with evidence of a seizure occurring within 7 days of a terminated ECT seizure. Data for demographic, medical, pharmacological, anesthetic, and ECT variables as well as management strategies were collected. RESULTS: There have been 39 episodes of modified ECT-related tardive seizures published over a period of 40 years. In 97.4% of cases, there was at least 1 identified potential risk factor for seizures, including use of a seizure-lowering medication and/or preexisting neurological injury. Major complications were uncommon (<15% of cases); however, 1 fetal death and 1 subsequent suicide were reported. No case was diagnosed with epilepsy, although around 20% continued on antiepileptic medications. More than half of the included patients were retrialed on ECT, with only 15% developing further tardive seizures. CONCLUSIONS: Seizures that occurred spontaneously after the termination of an ECT seizure are a rare complication of modified ECT. Recommencing ECT after a tardive seizure may occur after review of modifiable seizure risk factors and with consideration of antiepileptic medication and extended post-ECT monitoring.

Psychogenic nonepileptic seizures treated as epileptic seizures in the emergency department.

OBJECTIVES: We aimed to estimate the rate of psychogenic nonepileptic seizures (PNES) among patients presenting to an emergency department with presumed seizures. We also wanted to identify factors that can assist health care professionals in determining whether these events are likely to be epileptic or nonepileptic. METHODS: We performed two retrospective audits on patients who were treated for seizures in the department of emergency medicine at the Princess Alexandra Hospital, Brisbane, Australia. Exploratory analyses and logistic regressions were conducted to investigate the characteristics of the presentations and the relationships between our variables of interest. RESULTS: In the group of all presentations with presumed seizures over a 3-month period (n = 157), a total of 151 presentations (96.2%) presentations were given a primary diagnosis of epileptic seizures. Of these 151 presentations, only 84 (55.6%) presented with epileptic seizures and 40 (26.5%) actually presented with PNES. In the group of patients who presented with prolonged and/or multiple events (n = 213) over a 1-year period, 196 (92.0%) were treated as epileptic seizures. Of these 196 presentations, only 85 (43.4%) presented with epileptic seizures and 97 (49.5%) actually presented with PNES. Several factors were identified to help risk stratify between epileptic seizures and PNES: Duration of events and of the postictal phase, number of events, presence of a structural brain pathology, mental health history, lactate levels and presence of tongue bite, incontinence, and/or vomiting. SIGNIFICANCE: A large proportion of people who present to emergency departments with events resembling epileptic seizures actually have PNES rather than epilepsy-particularly those patients who present with prolonged and/or multiple events. The rate of misdiagnosis was high. Efforts need to be made to recognize patients with psychogenic nonepileptic seizures earlier and diagnose them correctly to avoid unnecessary iatrogenic harm and to provide adequate treatment.

Total dietary sugar consumption does not influence sleep or behaviour in Australian children.

This study aimed to compare sugar intake in Australian children with current guidelines and determine if total sugar consumption as a percentage of energy (sugar %E) exacerbates the relationship between sleep and behaviour. A sample of 287 children aged 8-12 years (boys 48.8%, age: 10.7 ± 1.3 years), and their parents/guardians completed a battery of questionnaires. Children completed a food frequency questionnaire, and parents completed demographic, sleep, and behaviour questionnaires. Average sugar intake was 134.9 ± 71.7 g per day (sugar %E 26.0 ± 7.0%), and only 55 (19%) participants did not exceed the recommended sugar intake limit. Correlations and logistical regressions indicated that sugar %E was not associated with sleep or behavioural domains (r range = -0.07-0.08; p range = .173-.979) nor contributed to the prediction of sleep behaviour problems (p range = .16-.80). Whilst a high proportion of children consumed above the recommended amount of daily total sugar, total sugar consumption was not related to behavioural or sleep problems, nor affected the relationship between these variables.

Reduction in cardiolipin decreases mitochondrial spare respiratory capacity and increases glucose transport into and across human brain cerebral microvascular endothelial cells.

Microvessel endothelial cells form part of the blood-brain barrier, a restrictively permeable interface that allows transport of only specific compounds into the brain. Cardiolipin is a mitochondrial phospholipid required for function of the electron transport chain and ATP generation. We examined the role of cardiolipin in maintaining mitochondrial function necessary to support barrier properties of brain microvessel endothelial cells. Knockdown of the terminal enzyme of cardiolipin synthesis, cardiolipin synthase, in hCMEC/D3 cells resulted in decreased cellular cardiolipin levels compared to controls. The reduction in cardiolipin resulted in decreased mitochondrial spare respiratory capacity, increased pyruvate kinase activity, and increased 2-deoxy-[(3) H]glucose uptake and glucose transporter-1 expression and localization to membranes in hCMEC/D3 cells compared to controls. The mechanism for the increase in glucose uptake was an increase in adenosine-5'-monophosphate kinase and protein kinase B activity and decreased glycogen synthase kinase 3 beta activity. Knockdown of cardiolipin synthase did not affect permeability of fluorescent dextran across confluent hCMEC/D3 monolayers grown on Transwell(®) inserts. In contrast, knockdown of cardiolipin synthase resulted in an increase in 2-deoxy-[(3) H]glucose transport across these monolayers compared to controls. The data indicate that in hCMEC/D3 cells, spare respiratory capacity is dependent on cardiolipin. In addition, reduction in cardiolipin in these cells alters their cellular energy status and this results in increased glucose transport into and across hCMEC/D3 monolayers. Microvessel endothelial cells form part of the blood-brain barrier, a restrictively permeable interface that allows transport of only specific compounds into the brain. In human adult brain endothelial cell hCMEC/D3 monolayers cultured on Transwell(®) plates, knockdown of cardiolipin synthase results in decrease in mitochondrial cardiolipin and decreased mitochondrial spare respiratory capacity. The reduced cardiolipin results in an increased activity of adenosine monophosphate kinase (pAMPK) and protein kinase B (pAKT) and decreased activity of glycogen synthase kinase 3 beta (pGSK3ß) which results in elevated glucose transporter-1 (GLUT-1) expression and association with membranes. This in turn increases 2-dexoyglucose uptake from the apical medium into the cells with a resultant 2-deoxyglucose movement into the basolateral medium.

Relative validity and reproducibility of an FFQ to determine nutrient intakes of New Zealand toddlers aged 12-24 months.

OBJECTIVE: The study objective was to determine the relative validity and reproducibility of a modified FFQ for ranking the nutrient intakes of New Zealand toddlers aged 12-24 months. DESIGN: Cross-sectional study. SETTING: Dunedin, New Zealand. SUBJECTS: One hundred and fifty-two participants completed a ninety-five-item FFQ twice, and five days of weighed diet recording (WDR), over one month. Validity and reproducibility were assessed for crude data and for data that were weighted for total fruit and vegetable intake (FV-adjusted). RESULTS: De-attenuated correlations between FV-adjusted FFQ data and WDR data ranged from 0.45 (Zn) to 0.77 (Ca). The percentage classified to the correct WDR quartile by the FV-adjusted FFQ data ranged from 34.6% (total fat, Zn) to 50.3% (Fe). Average gross misclassification was 3%. Bland-Altman statistics showed crude data had a range of 128-178% agreement with the WDR and mean FV-adjusted intakes had 112-160% agreement. FV-adjusted intra-class correlations, assessing reproducibility, ranged from 0.65 (vitamin C) to 0.75 (Ca). CONCLUSIONS: The Eating Assessment in Toddlers (EAT) FFQ showed acceptable to good relative validity, and good reproducibility, for ranking participants' nutrient intake and is able to identify toddlers at extremes of the nutrient intake distribution. It will be a useful tool for investigating toddlers' nutrient intakes in studies that require a method of dietary assessment with low respondent burden.

Recognition of Significantly Delayed Spinal Cord Ischemia Following Thoracic Endovascular Aortic Repair: A Case Report and Review of the Literature.

Spinal cord ischemia (SCI) is an uncommon but serious complication of thoracic endovascular aortic repair (TEVAR). SCI after TEVAR is thought to result from decreased segmental blood supply to an important network of collateral blood flow in the spinal cord. Little is known about the prevalence and optimal treatment of SCI that occurs beyond the periprocedural period. We report a case of delayed SCI in a 67-year-old patient who underwent TEVAR. The patient presented almost two years after TEVAR with acute paraplegia preceded by pre-syncope. The delayed SCI was likely triggered by pre-syncope, a thrombosed endoleak shown on imaging, and the patient's vascular risk factors. Treatments included cerebrospinal fluid (CSF) drainage, mean arterial pressure (MAP) augmentation, and a naloxone infusion, which resulted in moderate recovery in lower extremity motor function. This case highlights the tenuous nature of spinal cord perfusion after TEVAR and that prompt recognition and early treatment of SCI are critical in preventing the progression from ischemia to infarction.

Binocular summation in high and low contrast letter acuities.

Binocular summation, a well-known phenomenon in letter acuity measurement, refers to the improvement in visual performance when viewing with both eyes compared to one eye alone. The present study aims to assess the relationship in binocular summation between high and low contrast letter acuities, and examine whether baseline measure (binocular summation at either high or low contrast) is predictive of the change in binocular summation between contrast conditions. Corrected high and low contrast letter acuities were assessed monocularly and binocularly in 358 normal vision observers aged 18-37 years using Bailey-Lovie charts. All observers had high contrast acuities (both monocular and binocular) of 0.1 LogMAR or better and no known eye disease. Binocular summation was calculated as the difference in LogMAR between the better eye acuity and binocular acuity. We found that binocular summation was present at both contrast levels (0.044 ± 0.002 LogMAR for high and 0.069 ± 0.002 LogMAR for low contrast) with higher magnitude of summation at low contrast, and declined with increasing interocular difference. There was a correlation in binocular summation between high and low contrast. The difference in binocular summation between the two contrast levels was found to be correlated with the baseline measurement. Using common commercially available letter acuity charts, we replicated the findings on binocular acuity summation in normally sighted young adults for both high and low contrast letters. Our study revealed a positive relationship in binocular acuity summation between high and low contrast, and an association between a baseline measure and the change in binocular summation between contrast levels. These findings may serve as a reference in clinical practice and research when high and low contrast binocular summations are measured in assessing binocular functional vision.

Violence and delusional jealousy in Parkinson's disease.

Psychosis in Parkinson's disease (PD) can have a hugely detrimental effect on patient outcomes and quality of life. It can be a feature of PD itself, or can be exacerbated by the very pharmacological agents that are prescribed to treat the motor symptoms of the disease. The treatment of psychosis in PD is often complex, with clinicians having to balance the debilitating physical symptoms of PD against the risk of exacerbating the psychosis. We describe the case of an octogenarian who presented with violence motivated by delusional jealousy in the context of PD, who was treated in a specialist psychiatric inpatient environment.

Changes in patient activation in people starting dialysis: A prospective longitudinal, observational study.

INTRODUCTION: Increased patient activation is associated with improved health outcomes; however, little is known about patient activation in people with end-stage kidney disease at the start of their dialysis journey. This study aimed to measure activation status changes over the first 4 months of dialysis. METHODS: Prospective, longitudinal, and observational study. Incident patients initiating dialysis at 25 in-center hemodialysis and 17 home dialysis programs across three US states managed by the same dialysis provider completed the 13-item Patient Activation Measure (PAM-13) survey at baseline (month 1 after commencement of dialysis) and follow-up (month 4). The survey yields a score (0-100) that corresponds to four levels (1-4), with higher scores or levels indicating higher activation. FINDINGS: One hundred eighty-two participants (139 center, 43 home) completed both baseline and follow-up surveys. Mean age was 60 ± 15 years, 40% female. Mean PAM-13 scores were 65.1 ± 16.8 and 64.8 ± 17.8 at baseline and follow-up, respectively; mean intraindividual change: -0.3 ± 17.3. The proportions of patients at levels 1-4 at baseline were 11%, 23%, 35%, and 31% respectively. At follow-up, 50%, 64%, 52%, and 37% of participants at levels 1-4, respectively, changed to a different PAM level (Spearman correlation = 0.47; p < 0.001). Home dialysis was associated with higher PAM scores when compared to in-center hemodialysis in multivariable analyses, adjusted for sociodemographic variables, comorbidities, and predialysis nephrology care (ß = 5.74, 95% confidence intervals [CI]: 0.11-11.37 and 9.02, 95% CI: 3.03-15.02, at baseline and follow-up, respectively). DISCUSSION: Although aggregated group scores and levels remained stable, intra-individual patient activation changed significantly during the first 4 months of dialysis. This novel finding is foundational to future projects aiming to design interventions to improve patient activation.

Reframe the pain: Divided attention and positive memory reframing to reduce needle pain and distress in children-A feasibility randomized controlled trial.

BACKGROUND: Negative experiences of needle procedures in childhood can lead to medical avoidance and vaccine hesitancy into adulthood. We evaluated the feasibility of two new interventions provided by clinical nurses to reduce the negative impact of vaccinations: divided attention (DA) and positive memory reframing (PMR). METHODS: Children (8-12 years) were randomized into four groups: usual care (UC), DA, PMR or combined (DA + PMR). To evaluate feasibility, we undertook in-depth analysis of video-recorded interventions, nurse experiences (phone interviews) and child/parent memory recall of interventions (phone interviews at 2 weeks post-vaccination). Key clinical outcomes included child and parent ratings of needle-related pain intensity and fear assessed at baseline, immediately post-vaccination and 2 weeks post-vaccination (recalled). RESULTS: A total of 54 child-parent dyads were screened, with 41 included (10/group, except PMR [n = 11]). The interventions were not always completed as intended: 10%-22% of participants received complete interventions and two had adverse events related to protocol breach. Preliminary within-group analyses showed no effects on child/parent pain ratings. However, children in DA + PMR had reduced recalled fear (p = 0.008), and PMR (p = 0.025) and DA + PMR (p = 0.003) had reduced fear of future needles. Parent ratings of child fear were also reduced immediately post-vaccination for UC (p = 0.035) and PMR (p = 0.035). CONCLUSIONS: The interventions were feasible, although enhanced nurse training is required to improve fidelity. Preliminary clinical results appear promising, particularly for reducing needle-related fear. PROTOCOL REGISTRATION: Protocol number ACTRN12618000687291 at ANZCTR.org.au SIGNIFICANCE: Two new nurse-led interventions to reduce negative impacts of vaccinations in children, divided attention and positive memory reframing, were feasible and may reduce needle-related fear. Nurses were able to deliver the interventions in various environments including non-clinical settings (schools). These interventions have potential to facilitate broader dissemination of vaccinations for children in a manner that minimizes distress.

Patient Activation Among Prevalent Hemodialysis Patients: An Observational Cross-Sectional Study.

Patient activation is the product of knowledge, skills, and confidence that enables a person to manage their own healthcare. It is associated with healthy behaviors and improved patient outcomes. We surveyed prevalent hemodialysis (HD) patients at 10 centers using the Patient Activation Measure 13-item instrument (PAM-13). Activation was reported as scores (0-100) and corresponding levels (1-4). Of 1149 eligible patients, surveys were completed by 925 patients (92% response rate). Mean age was 62 ± 14 years, 40% were female, median vintage was 41 (IQR 19-77) months, and 66% had diabetes. Mean PAM score was 56 ± 13, with 14%, 50%, 25%, and 10% in levels 1 to 4, respectively. In adjusted analysis, older age and having diabetes were associated with lower activation, whereas higher educational levels and female gender were associated with higher scores. Significant variation in activation was observed among participants from different centers even after adjustment for other variables. In conclusion, low activation is common among prevalent HD patients.

Acute GVHD, BK virus hemorrhagic cystitis and age are risk factors for transplant-associated thrombotic microangiopathy in adults.

Hematopoietic cell transplantation-associated thrombotic microangiopathy (TMA) is a complication associated with higher nonrelapse mortality (NRM) in patients who undergo allogeneic transplant (HCT). Current classification criteria are not generally agreed on or validated, and the presence of confounding factors after transplant contribute to underdiagnosis or delayed diagnosis of TMA. We studied risk factors, incidence, and biomarkers of TMA in 119 adult allogeneic HCT recipients. Twenty-seven patients developed a clinically actionable phenotype of TMA (CA-TMA) and the incidence of CA-TMA was 22% by day 180. Among the 27 patients who developed CA-TMA, 10 developed it before the onset of acute graft-versus-host disease (aGVHD), and 17 patients developed it after the onset of aGVHD. We report for the first time that age >50 years, BK hemorrhagic cystitis, and other viral infections (CMV, HHV-6, or adenovirus) are risk factors for adult CA-TMA. Even after adjustment for aGVHD, CA-TMA was independently associated with significantly higher NRM. These data illustrate relationships between CA-TMA and aGVHD, describe new risk factors for CA-TMA and emphasizes the need to develop validated set of criteria for timely diagnosis.

Genetic and Epigenetic Interplay Within a COLGALT2 Enhancer Associated With Osteoarthritis.

OBJECTIVE: The osteoarthritis (OA)-associated single-nucleotide polymorphism (SNP) rs11583641 is located in COLGALT2, encoding a posttranslational modifier of collagen. In cartilage, the SNP genotype correlates with DNA methylation in a putative enhancer. This study was undertaken to characterize the mechanistic relationship between rs11583641, the putative enhancer, and COLGALT2 expression using cartilage samples from human patients and a chondrocyte cell model. METHODS: Nucleic acids were extracted from articular cartilage samples obtained from patients with OA (n = 137). Samples were genotyped, and DNA methylation was quantified at 12 CpGs using pyrosequencing. The putative enhancer was deleted in Tc28a2 chondrocytes using clustered regularly interspaced short palindromic repeat/Cas9, and the impact on nearby gene expression was determined using real-time quantitative polymerase chain reaction. Targeted modulation of the epigenome using catalytically dead Cas9 (dCas9) constructs fused to DNA methyltransferase 3a or ten-eleven translocase 1 allowed for the investigation of a causal relationship between DNA methylation and enhancer activity. RESULTS: The genotype at rs11583641 correlated with DNA methylation at 3 CpGs, and the presence of the OA risk allele, C, corresponded to reduced levels of methylation. Deletion of the enhancer resulted in a 2.7-fold reduction in COLGALT2 expression. Targeted methylation and demethylation of the CpGs had antagonistic effects on COLGALT2 expression. An allelic imbalance in the expression of COLGALT2 was identified in the cartilage from patients with OA, with relative overexpression of the OA risk allele. Allelic expression ratios correlated with DNA methylation at 4 CpGs. CONCLUSION: COLGALT2 is a target of OA genetic risk at this locus. The genotype at rs11583641 impacts DNA methylation in a gene enhancer, which, in turn, modulates COLGALT2 expression. COLGALT2 encodes an enzyme that initiates posttranslational glycosylation of collagens and is therefore a compelling OA susceptibility target.

Characterization of Horse Use in Therapeutic Horseback Riding Programs in the United States: A Pilot Survey.

With increasing public scrutiny on animal welfare, it behooves those involved in the equine industry to revisit best management practices to ensure these support healthy horses. There is little published research on how horses are used in the equine industry, particularly in therapeutic horseback riding (THR) programs. Although there is a large amount of information on the benefits of THR programs to the participants, there is little published information available about the horses. Therefore, the objective of this survey was to gather data regarding horse use and care in Professional Association of Therapeutic Horsemanship International (PATH Intl.)-affiliated THR programs in the United States to help establish a foundation for a standard of care. A 20-question survey sent to 659 PATH Intl.-affiliated THR programs returned a 40% response rate. Demographics demonstrated that the median number of horses in each program was 10; geldings outnumbered mares; most horses were between 16 and 20 years of age; and Quarter Horse or stock-type breeds predominated. Median session length was 8 weeks and median lesson length was 45 minutes. Horses were typically ridden by clients 4 days/week and 2 hours/day. Most horses were donated to the programs, participated for approximately 7 years, and left because of aging. Limb lameness and back soreness were the top health issues noted, with only a small percentage of colic and ulcers reported. More horses received nonsteroidal anti-inflammatory drugs for a lameness issue, chiropractic adjustment, and massage than any other supplemental care or complementary therapy. Based on data gathered in this survey, THR horses were not worked excessively. Horses were ridden less than PATH Intl.'s maximum recommendation of 6 hours/day and 6 days/week and less than those used in university programs. Horses in THR programs also appeared to have fewer reported health issues as compared with data in other national reports.

Genetic microheterogeneity and phenotypic variation of Helicobacter pylori arginase in clinical isolates.

BACKGROUND: Clinical isolates of the gastric pathogen Helicobacter pylori display a high level of genetic macro- and microheterogeneity, featuring a panmictic, rather than clonal structure. The ability of H. pylori to survive the stomach acid is due, in part, to the arginase-urease enzyme system. Arginase (RocF) hydrolyzes L-arginine to L-ornithine and urea, and urease hydrolyzes urea to carbon dioxide and ammonium, which can neutralize acid. RESULTS: The degree of variation in arginase was explored at the DNA sequence, enzyme activity and protein expression levels. To this end, arginase activity was measured from 73 minimally-passaged clinical isolates and six laboratory-adapted strains of H. pylori. The rocF gene from 21 of the strains was cloned into genetically stable E. coli and the enzyme activities measured. Arginase activity was found to substantially vary (>100-fold) in both different H. pylori strains and in the E. coli model. Western blot analysis revealed a positive correlation between activity and amount of protein expressed in most H. pylori strains. Several H. pylori strains featured altered arginase activity upon in vitro passage. Pairwise alignments of the 21 rocF genes plus strain J99 revealed extensive microheterogeneity in the promoter region and 3' end of the rocF coding region. Amino acid S232, which was I232 in the arginase-negative clinical strain A2, was critical for arginase activity. CONCLUSION: These studies demonstrated that H. pylori arginase exhibits extensive genotypic and phenotypic variation which may be used to understand mechanisms of microheterogeneity in H. pylori.

The Relationship Between Caffeine, Sleep, and Behavior in Children.

STUDY OBJECTIVES: To examine caffeine consumption from various dietary sources in a cohort of Australian children and the relationship between caffeine consumption, sleep, and daytime behavior. METHODS: Children aged 8 to 12 years and their parents/guardians completed a battery of questionnaires. Children completed a caffeine questionnaire while parents completed questionnaires regarding demographics, sleep, and behavior. RESULTS: The final sample consisted of 309 children (mean ± standard deviation [SD] age 10.6 ± 1.3 years, male = 48%) and corresponding parent reports. On average a mean ± SD 10.2 ± 17.4 mg/day of caffeine was consumed with a range of zero to 151 mg/day. Of the children who consumed caffeine (87% of the sample), the largest contributor was coffee and tea; making up 41% of total caffeine intake, and sodas (soft drinks) contributed to 40% of caffeine intake. Total caffeine consumption was significantly associated with sleep routine (r = 0.152); morning tiredness (r = 0.129); restless sleep (r = 0.113); and internalizing behavioral problems (r = 0.128). Using path analysis, caffeine consumption was positively associated with morning tiredness (ß = 0.111, P = .050) which was positively associated with internalizing behaviors (ß = 0.432, P < .001). The addition of sleep routine and restless sleep to the model led to a complete mediation of caffeine consumption on morning tiredness, as well as a partial mediation of the association between morning tiredness and internal behaviors. CONCLUSIONS: In 8- to 12-year-olds the primary sources of caffeine are coffee/tea and sodas. Overall mean caffeine consumption is small by adult standards but has an effect on behavior and sleep in children. The effect on behavior is mediated by disrupted sleep, indicating that caffeine is a contributor to sleep problems and related behavior in children.