Three-Dimensional-Printed Electrochemical Multiwell Plates for Monitoring Food Intolerance from Intestinal Organoids

Common symptoms of food intolerance are caused by chemical components within food that have a pharmacological activity to alter the motility of the gastrointestinal tract. Food intolerance is difficult to diagnose as it requires a long-term process of eliminating foods that are responsible for gastrointestinal symptoms. Enterochromaffin (EC) cells are key intestinal epithelium cells that respond to luminal chemical stimulants by releasing 5-HT. Changes in 5-HT levels have been shown to directly alter the motility of the intestinal tract. Therefore, a rapid approach for monitoring the impact of chemicals in food components on 5-HT levels can provide a personalized insight into food intolerance and help stratify diets. Within this study, we developed a three-dimensional (3D)-printed electrochemical multiwell plate to determine changes in 5-HT levels from intestinal organoids that were exposed to varying chemical components found in food. The carbon black/poly-lactic acid (CB/PLA) electrodes had a linear range in physiological concentrations of 5-HT (0.1-2 μM) with a limit of detection of 0.07 μM. The electrodes were stable for monitoring 5-HT overflow from intestinal organoids. Using the electrochemical multiwell plate containing intestinal organoids, increases in 5-HT were observed in the presence of 0.1 mM cinnamaldehyde and 10 mM quercetin but reduction in 5-HT levels was observed in 1 mM sorbitol when compared to control. These changes in the presence of chemicals commonly found in food were verified with ex vivo ileum tissue measurements using chromatography and amperometry with boron-doped diamond electrodes. Overall, our 3D electrochemical multiwell plate measurements with intestinal organoids highlight an approach that can be a high-throughput platform technology for rapid screening of food intolerance to provide personalized nutritional diet.

3D Printed Electrochemical Sensors

Three-dimensional (3D) printing has recently emerged as a novel approach in the development of electrochemical sensors. This approach to fabrication has provided a tremendous opportunity to make complex geometries of electrodes at high precision. The most widely used approach for fabrication is fused deposition modeling; however, other approaches facilitate making smaller geometries or expanding the range of materials that can be printed. The generation of complete analytical devices, such as electrochemical flow cells, provides an example of the array of analytical tools that can be developed. This review highlights the fabrication, design, preparation, and applications of 3D printed electrochemical sensors. Such developments have begun to highlight the vast potential that 3D printed electrochemical sensors can have compared to other strategies in sensor development.

POS1034 RESPONSE TO SEQUENTIAL LINES OF BIOLOGICAL THERAPY IN PSORIATIC ARTHRITIS: A SINGLE CENTRE COHORT STUDY

Background:

Biologic interventions using highly specific immuno-modulatory biologic disease-modifying anti-rheumatic drugs (bDMARDs) represent a rapidly developing therapeutic approach to the treatment of Psoriatic Arthritis (PsA). However, despite high rates of response, adverse events, primary and secondary inefficacy are common, and multiple sequential lines of bDMARDs are often required. Data on drug persistence, as a surrogate for response, from national registries indicates switching has become accepted routine practice. One third of patients will fail or discontinue their first biologic with a significant proportion switching on to a 3rd biologic or higher.1-4 Due to a lack of evidence on the response to sequential therapies, individual patients may not have further lines routinely funded after three bDMARDs in the UK. While limiting lines of therapy remains a UK concern, many countries with rationed healthcare systems follow the UK model of drug usage.

Objectives:

To describe the response to sequential lines of bDMARD therapy prescribed in routine care in a UK single centre cohort.

Methods:

A retrospective sample of patients with PsA who fulfilled CASPAR criteria and had received at least one bDMARD were taken from the Bath longitudinal cohort for inclusion in the study. Clinical and laboratory variables that constitute physician and patient-reported outcome measures were collected at baseline and after a median (range) follow-up of 3 months (2-5) into their respective therapy line in accordance with the National Institute for Health and Care Excellence (NICE) rules. The mean change with a 95% confidence interval (CI) was used to report the difference between the baseline and follow-up measures. All patients provided consent to use their data collected during routine care, and ethical approval by the local committee was granted.

Results:

The patients mean age was 57.7 (SD 12.2) with a median (range) disease duration of 14.4 years (9.7 – 23.2). Data was available for 194 patients commencing 1st line bDMARD, 106 (2nd line), 93 (3rd line), 33 (4th line), 12 (5th line), and 9 (6th line and higher) from a total of 759 patients in the cohort. Mean tender and swollen joint count at baseline 1st bDMARD was 7 (SD 4.7) and 22 (SD 14.0), pain visual analogue scale 50 (SD 27.6) and PASI 1.3 (SD 2.2). Reasons for changing biological therapies include lack or loss of efficacy, intolerance, side effects, and comorbidities. Mean levels of joint disease at drug initiation did not diminish with subsequent lines of therapy. Clinical and patient reported outcomes by line of therapy are reported in Figure 1. Clinical responses were greatest to first line bDMARD, however clinically relevant DAPSA improvements were seen up to 5th line. Absolute levels of psoriasis in the cohort were low, however improvement in PASI was achieved across all lines of therapy. Patient and Physician Global Assessments (1-5 on Likert scale) and the Pain Visual analogue score (VAS on 1-10 Likert scale) showed a similar trend with greatest improvement to first line treatment across all lines of therapy.

Conclusion:

In this study we report the clinical response to sequential lines of bDMARD therapy for active PsA in routine clinical practice. Clinical response was greatest to the first line bDMARD but overall improvement in DAPSA, PASI or pain response did not appear to diminish up to 5th line. Further study in larger cohorts is required to confirm this finding and build on our understanding of clinical response to sequential lines of bDMARD therapy.

References:

[1]Hyrish et al 2006 Rheum 45, 1558-65

[2]Kawabe A. 2020 Arth Res Ther 22, 136

[3]Park DJ. 2017 Clin Rheum 36, 1013-22

[4]Karlsson. 2007 JA Rheum 47,507-13

Figure 1.

Clinical and patient reported outcomes by line of therapy

Disclosure of Interests:

Abuelmagd Abdalla: None declared, Adwaye Rambojun: None declared, Laura C Coates Speakers bureau: AbbVie, Amgen, Biogen, Celgene, Gilead, Eli Lilly, Janssen, Medac, Novartis, Pfizer, and UCB., Consultant of: AbbVie, Amgen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Eli Lilly, Gilead, Janssen, Novartis, Pfizer, and UCB, Grant/research support from: AbbVie, Amgen, Celgene, Eli Lilly, Pfizer, and Novartis, Eleanor Korendowych Consultant of: Abbvie, Celgene, Janssen, Lilly and Novartis., Neil McHugh: None declared, William Tillett Speakers bureau: AbbVie, Amgen, Celgene, Lilly, Janssen, Novartis, Pfizer Inc., and UCB, Consultant of: AbbVie, Amgen, Celgene, Lilly, Janssen, Novartis, MSD, Pfizer Inc., and UCB., Grant/research support from: AbbVie, Celgene, Eli Lilly, Janssen, Novartis, Pfizer Inc., and UCB.

P100 Acute crystal arthritis: a leading cause of hospital admission, yet poorly recognised and mistreated

Background/Aims 

Crystal arthritis is the commonest inflammatory arthritis in adults. A common mimic is septic arthritis. Without appropriate synovial fluid analysis, a mis-diagnosis of sepsis can be made with resultant unnecessary hospitalization, inappropriate intravenous antibiotic therapy and excess cost. Such cases are frequently described as ‘culture-negative’ septic arthritis. We aimed to examine and analyse the cases of acute arthritis requiring acute hospital admission in a tertiary referral centre in Dublin.

Methods 

A retrospective review of database between Jan - Dec 2019 at the Mater Misericordiae University Hospital, Dublin, was carried out. All cases of acute arthritis requiring acute hospital admission were identified. Cases treated at the Emergency Department, Acute Medical Unit or Outpatients which did not require hospital admission were excluded.

Results 

30 patients were identified during this period, 16 (53%) had an ultimate diagnosis of crystal arthritis, 8 (27%) had confirmed septic arthritis and 6 (20%) had other arthritides (e.g. haemoarthrosis). The median age for crystal arthritis was significantly higher (85.5 y) compared to septic arthritis (47 y). Apart from age, the clinical profile and biomarkers for crystal and septic arthritis were comparable. The majority of crystal arthritis cases were due to pseudogout (69 %), ultimately diagnosed by rheumatology. Septic arthritis led to more days in hospital than crystal arthritis (median 14 vs 5.5 days). All 30 patients received IV antimicrobial therapy for presumed septic arthritis.

Conclusion 

This retrospective study showed crystal arthritis, especially pseudogout, was the commonest cause of hospital admission (53%) with acute arthritis particularly among elderly patients. Accurate diagnosis by synovial fluid analysis with appropriate equipment is extremely useful in the assessment of these cases. More awareness and training among orthopedic, emergency and acute clinicians is needed in order to avoid unnecessary admissions and interventions.

Disclosure 

A. Abdalla: None.

P004 Rheumatologist vs pathology department: correlation of crystal identification in synovial fluid analysis

Background/Aims 

Crystal arthritis is the commonest inflammatory arthritis in adults. Diagnosis relies mostly on the correct identification of crystals under red-compensated polarized microscopy with assessment of birefringence. This is done routinely in our department when opportunity arises. Failure to appropriately identify crystals may result in lengthy hospitalisations, complications, avoidable repeated urgent visits, and unnecessary cost. We aimed to examine the agreement between rheumatology vs pathology-based microscopy for crystal analysis. There is currently no standardized pathway for synovial fluid crystal analysis in our tertiary centre in Dublin.

Methods 

A prospective study at Mater Misericordiae University Hospital - Dublin, was started in Dec 2019. Synovial fluid samples were obtained from acutely inflamed joints where clinically indicated. Fresh samples which were found to contain crystals (MSU or CPP) by a rheumatology consultant or trained registrar using compensated polarized microscopy, were also simultaneously sent to our pathology laboratory to receive similar analysis. Ethical approval was granted and all patients consented for their joint fluid to receive double analysis.

Results 

33 samples have been analysed to date. 13 samples of MSU crystals and 20 CPP crystals (table 1). Both rheumatologist and pathologist agreed on all but only one MSU sample. The pathologist identified CPP crystals only on 2/20 samples. The fluid analysis was carried out within the same working day by rheumatologist Vs. median of 2.3 working days for the result by the pathologist.

Conclusion 

The study showed a high agreement between rheumatologists and pathologists on identification of MSU crystals (92%), but very poor agreement on CPP crystals (only 10%). A quality improvement project is currently underway to address this issue and bridge the gap. Majority of Rheumatologists don't routinely perform crystal analysis using polarized microscopy and rely on their local cellular pathology lab for the results. Rheumatologists need to liaise with their local pathologists to optimise and streamline the process of crystal microscopy specially CPP crystals. P004 Table 1:crystals samples analysed through rheumatology and pathologyCPPD positiveMSU positiveRheumatologist2013Pathologist212Total2013

Disclosure 

A. Abdalla: None.

Ex Vivo Electrochemical pH Mapping of the Gastrointestinal Tract in the Absence and Presence of Pharmacological Agents

Ex vivo pH profiling of the upper gastrointestinal (GI) tract (of a mouse), using an electrochemical pH probe, in both the absence and presence of pharmacological agents aimed at altering acid/bicarbonate production, is reported. Three pH electrodes were first assessed for suitability using a GI tract biological mimic buffer solution containing 0.5% mucin. These include a traditional glass pH probe, an iridium oxide (IrOx)-coated electrode (both operated potentiometrically), and a quinone (Q) surface-integrated boron-doped diamond (BDD-Q) electrode (voltammetric). In mucin, the time scale for both IrOx and glass to provide a representative pH reading was in the ∼100's of s, most likely due to mucin adsorption, in contrast to 6 s with the BDD-Q electrode. Both the glass and IrOx pH electrodes were also compromised on robustness due to fragility and delamination (IrOx) issues; contact with the GI tissue was an experimental requirement. BDD-Q was deemed the most appropriate. Ten measurements were made along the GI tract, esophagus (1), stomach (5), and duodenum (4). Under buffer only conditions, the BDD-Q probe tracked the pH from neutral in the esophagus to acidic in the stomach and rising to more alkaline in the duodenum. In the presence of omeprazole, a proton pump inhibitor, the body regions of the stomach exhibited elevated pH levels. Under melatonin treatment (a bicarbonate agonist and acid inhibitor), both the body of the stomach and the duodenum showed elevated pH levels. This study demonstrates the versatility of the BDD-Q pH electrode for real-time ex vivo biological tissue measurements.

AB0394 DOES HIGH DISEASE ACTIVITY IN SYSTEMIC LUPUS ERYTHEMATOSUS PATIENTS INCREASE THE RISK OF CANCER INCIDENCE?

Background:

Cancer is known as one of the causes of morbidity and mortality in systemic lupus erythematosus (SLE) patients. It has been thought that SLE activity and stimulation of the immune system predisposes the risk of cancer (1).

Objectives:

To investigate the correlation between SLE disease activity and the cancer incidence.

Methods:

The study included a cohort of SLE patients, diagnosed according to the American College of Rheumatology classification criteria(2)attending the Rheumatology department, Aswan University in the period from January 2018 to June 2019. We used a questionnaire to screen patients who were diagnosed with cancer. We collected demographic and laboratory data on all screened patients and their disease activity using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)(3). For the patients diagnosed with cancer, we recorded age of onset of SLE, age of diagnosis of cancer, type of cancer, treatment received, immunosuppressive regimen (dosage and duration) and cancer outcomes.

Results:

The study included 117 patients (95 female, 22 male), mean age (25.6 ± 6.5) years with mean SLE duration(7.3 ±6.3) years and mean SLEDAI(9± 8.9). 76% had lupus nephritis, 62.2% had hematological abnormalities and 17.8%had neurophsycatric lupus. 91% were on corticosteroids (CCS), 33% on mycophenolate mofetil (MMF), 43% on azathioprine, 14% on cyclosporin. 56.8% were either receiving or had received intravenous cyclophosphamide (CYC) with a mean cumulative dose (7.5 ± 4.7) gm. We found 18 (15.3%) patients (13 female and 5 males) were diagnosed with cancer during the course of SLE with mean age at onset (31±3.7), mean age at cancer diagnosis (39.28±10.77), mean SLE duration(18.17±6.02) and mean SLEDAI (7.39±4.19). Most of SLE patients with cancer had lupus nephritis (89%) and all cancer patients were on a median dose of CCS 10 (2.5- 20) mg daily for median 10 (4-24) years. 83.5% of them had received intravenous CYC prior to the development of cancer with mean total cumulative dose of (6.7±4.6) gm, 67% received MMF, 33% received cyclosporine and 50% received azathioprine. Types of cancer were as follow; 22.2% lymphoma, 16.7% cancer cervix, 16.7% cancer breast, 11.1% colorectal cancer, 11.1% squamous cell carcinoma, 5.6% leukemia, 5.6% bronchogenic carcinoma, 5.6% prostate cancer and 5.6% cancer thyroid. 66.7% of them had been successfully treated, 27.8% had metastasis, 5.6% had died. There was no significant difference in SLEDAI between patients with cancer and patients without. Whereas malignancy is correlated to longer disease duration (p= 0.01) and older age of SLE onset with significant difference (p= 0.001).

Conclusion:

Although we have detected an increasing incidence of cancer in SLE patients in comparison to normal population, our study didn’t find a signficant correlation between SLE disease activity and the risk of cancer. We should closely observe SLE patients with old age at onset and/or long disease duration because of their higher risk for cancer development.

References:

[1]Bernatsky S, Ramsey-Goldman R, Joseph L, et al (2014). Lymphoma risk in systemic lupus: effects of disease activity versus treatment. Ann Rheum Dis, 73, 138–42.

[2]Hochberg MC (1997). Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum, 40, 1725.

[3]Bombardier C, Gladman DD, Urowitz MB, Caron D, Chang CH (1992) Derivation of the SLEDAI. A disease activity index for lupus patients. The Committee on Prognosis Studies in SLE. Arthritis Rheum:630–640.

Disclosure of Interests:

None declared

Fast serotonin voltammetry as a versatile tool for mapping dynamic tissue architecture: I. Responses at carbon fibers describe local tissue physiology

It is important to monitor serotonin neurochemistry in the context of brain disorders. Specifically, a better understanding of biophysical alterations and associated biochemical functionality within subregions of the brain will enable better of understanding of diseases such as depression. Fast voltammetric tools at carbon fiber microelectrodes provide an opportunity to make direct evoked and ambient serotonin measurements in vivo in mice. In this study, we characterize novel stimulation and measurement circuitries for serotonin analyses in brain regions relevant to psychiatric disease. Evoked and ambient serotonin in these brain areas, the CA2 region of the hippocampus and the medial prefrontal cortex, are compared to ambient and evoked serotonin in the substantia nigra pars reticulata, an area well established previously for serotonin measurements with fast voltammetry. Stimulation of a common axonal location evoked serotonin in all three brain regions. Differences are observed in the serotonin release and reuptake profiles between these three brain areas which we hypothesize to arise from tissue physiology heterogeneity around the carbon fiber microelectrodes. We validate this hypothesis mathematically and via confocal imaging. We thereby show that fast voltammetric methods can provide accurate information about local physiology and highlight implications for chemical mapping. Cover Image for this issue: doi: 10.1111/jnc.14739.

Determination of tryptophan metabolism from biological tissues and fluids using high performance liquid chromatography with simultaneous dual electrochemical detection

Serotonin and kynurenine are formed following metabolism of the essential amino acid tryptophan. Both molecules play important biological roles and the balance of how tryptophan metabolism varies to either the serotonin or kynurenine pathway may provide key insight into the inflammatory status of the biological region. At present complex chromatographic methods are utilised which predominately focus on either monitoring analytes in the serotonin or kynurenine pathway rather than both. Our study develops a simple yet robust methodology for the monitoring of tryptophan metabolism. We utilised isocratic reverse phase high-performance liquid chromatography with simultaneously dual electrochemical detection. This approach allowed for separation of co-eluted analytes and identification of analytes from both pathways within 14 minutes. For all analytes, limits of detection were <35 nM. No crosstalk was observed when dual simultaneous detection was conducted in a radial flow cell. Responses from the hippocampus, blood and ileum mucosa highlighted that each region had a varying ratio of serotonin to kynurenine pathway, indicating varied approaches to tryptophan metabolism. The developed method can monitor how the metabolism of tryptophan varies between the two pathways which can provide insight into the inflammatory state of reach region with age and disease.

Estimating Concentration Response Function and Change-Point using Time-Course and Calibration Data

In this paper the problem of determining the functional relationship between time and the concentration of a chemical substance is studied. An intervention drug is administered on the experimental unit from which the chemical substance (specimen) is measured. This drug is hypothesized to cause a change in the concentration level of the chemical substance a certain lag-time after the intervention. However, the concentration value could not be directly measured, but rather a surrogate response can be measured. In the time-course study, this surrogate response is measured using different electrodes which possess varied behaviors. To utilize these surrogate measurements arising from the different electrodes (sensors), a calibration study is undertaken which measures the surrogate response for the different electrodes at known concentration levels. Based on the time-course and calibration data sets, a statistical procedure to estimate the signal function and the lag-time is proposed. Simulation studies indicate that the proposed procedure is able to reasonably recover the signal function and the lag-time. The procedure is then applied to the real data sets obtained during an analytical chemistry experiment.

Correction to: Intrinsic and inducible resistance to hydrogen peroxide in Bifidobacterium species

In the published article, the co-author Abdelmoneim Abdalla’s affiliation has been published incompletely. The additional affiliation is given below:

Voltammetric evidence for discrete serotonin circuits, linked to specific reuptake domains, in the mouse medial prefrontal cortex

The medial prefrontal cortex (mPFC) is an important brain region, that controls a variety of behavioral and functional outputs. As an important step in characterizing mPFC functionality, in this paper we focus on chemically defining serotonin transmission in this area. We apply cutting-edge analytical methods, fast-scan cyclic voltammetry (FSCV) and fast-scan controlled adsorption cyclic voltammetry (FSCAV), pioneered in our laboratory, for the first real-time in vivo analysis of serotonin in the mPFC. In prior in vivo work in the substantia nigra, pars reticulata, we found that our sub-second measurements of a single evoked serotonin release were subject to two clearance mechanisms. These mechanisms were readily modeled via Uptake 1, mediated by the serotonin transporters (SERTs), and Uptake 2, mediated by monoamine transporters (dopamine transporters (DATs), norepinephrine transporters (NETs), and organic cation transporters (OCTs)). Here in the mPFC, for the first time to our knowledge, we observe two release events in response to a single stimulation of the medial forebrain bundle (MFB). Of particular note is that each response is tied to a discrete reuptake profile comprising both Uptake 1 and 2. We hypothesize that two distinct populations of serotonin axons traverse the MFB and terminate in different domains with specific reuptake profiles. We test and confirm this hypothesis using a multifaceted pharmacological, histological and mathematical approach. We thus present evidence for a highly elaborate biochemical organization that regulates serotonin chemistry in the mPFC. This knowledge provides a solid foundation on which to base future studies of the involvement of the mPFC in brain function and behavior.

In Vivo Ambient Serotonin Measurements at Carbon-Fiber Microelectrodes

The mechanisms that control extracellular serotonin levels in vivo are not well-defined. This shortcoming makes it very challenging to diagnose and treat the many psychiatric disorders in which serotonin is implicated. Fast-scan cyclic voltammetry (FSCV) can measure rapid serotonin release and reuptake events but cannot report critically important ambient serotonin levels. In this Article, we use fast-scan controlled adsorption voltammetry (FSCAV), to measure serotonin's steady-state, extracellular chemistry. We characterize the "Jackson" voltammetric waveform for FSCAV and show highly stable, selective, and sensitive ambient serotonin measurements in vitro. In vivo, we report basal serotonin levels in the CA2 region of the hippocampus as 64.9 ± 2.3 nM (n = 15 mice, weighted average ± standard error). We electrochemically and pharmacologically verify the selectivity of the serotonin signal. Finally, we develop a statistical model that incorporates the uncertainty in in vivo measurements, in addition to electrode variability, to more critically analyze the time course of pharmacological data. Our novel method is a uniquely powerful analysis tool that can provide deeper insights into the mechanisms that control serotonin's extracellular levels.

The learning curve for interpretation of oesophageal high-resolution manometry: a prospective interventional cohort study

BACKGROUND

High-resolution manometry has become the preferred choice of oesophagologists for oesophageal motor assessment, but the learning curve among trainees remains unclear.

AIM

To determine the learning curve of high-resolution manometry interpretation.

METHODS

A prospective interventional cohort study was performed on 18 gastroenterology trainees, naïve to high-resolution manometry (median age 32 ± 4.0 years, 44.4% female). An intake questionnaire and a 1-h standardised didactic session were performed at baseline. Multiple 1-h interpretation sessions were then conducted periodically over 15 months where 10 studies were discussed; 5 additional test studies were provided for interpretation, and results were compared to gold standard interpretation by the senior author. Hypothetical management decisions based on trainee interpretation were separately queried. Accuracy was compared across test interpretations and sessions to determine the learning curve, with a goal of 90% accuracy.

RESULTS

Baseline accuracy was low for abnormal body motor patterns (53.3%), but higher for achalasia/outflow obstruction (65.9%). Recognition of achalasia reached 90% accuracy after six sessions (P = 0.01), while overall accurate management decisions reached this threshold by the 4th session (P < 0.001). Based on our data, the threshold of 90% accuracy for recognition of any abnormal from normal pattern was reached after 30 studies (3rd session) but fluctuated. Diagnosis of oesophageal body motor patterns remained suboptimal; accuracy of advisability of fundoplication improved, but did not reach 90%.

CONCLUSIONS

High-resolution manometry has a steep learning curve among trainees. Achalasia recognition is achieved early, but diagnosis of other abnormal motor patterns and management decisions require further supervised training.

Regrowth of Serotonin Axons in the Adult Mouse Brain Following Injury

It is widely believed that damaged axons in the adult mammalian brain have little capacity to regrow, thereby impeding functional recovery after injury. Studies using fixed tissue have suggested that serotonin neurons might be a notable exception, but remain inconclusive. We have employed in vivo two-photon microscopy to produce time-lapse images of serotonin axons in the neocortex of the adult mouse. Serotonin axons undergo massive retrograde degeneration following amphetamine treatment and subsequent slow recovery of axonal density, which is dominated by new growth with little contribution from local sprouting. A stab injury that transects serotonin axons running in the neocortex is followed by local regression of cut serotonin axons and followed by regrowth from cut ends into and across the stab rift zone. Regrowing serotonin axons do not follow the pathways left by degenerated axons. The regrown axons release serotonin and their regrowth is correlated with recovery in behavioral tests.

A voltammetric and mathematical analysis of histaminergic modulation of serotonin in the mouse hypothalamus

Histamine and serotonin are neuromodulators which facilitate numerous, diverse neurological functions. Being co-localized in many brain regions, these two neurotransmitters are thought to modulate one another's chemistry and are often implicated in the etiology of disease. Thus, it is desirable to interpret the in vivo chemistry underlying neurotransmission of these two molecules to better define their roles in health and disease. In this work, we describe a voltammetric approach to monitoring serotonin and histamine simultaneously in real time. Via electrical stimulation of the axonal bundles in the medial forebrain bundle, histamine release was evoked in the mouse premammillary nucleus. We found that histamine release was accompanied by a rapid, potent inhibition of serotonin in a concentration-dependent manner. We developed mathematical models to capture the experimental time courses of histamine and serotonin, which necessitated incorporation of an inhibitory receptor on serotonin neurons. We employed pharmacological experiments to verify that this serotonin inhibition was mediated by H3 receptors. Our novel approach provides fundamental mechanistic insights that can be used to examine the full extent of interconnectivity between histamine and serotonin in the brain. Histamine and serotonin are co-implicated in many of the brain's functions. In this paper, we develop a novel voltammetric method for simultaneous real-time monitoring of histamine and serotonin in the mouse premammillary nucleus. Electrical stimulation of the medial forebrain bundle evokes histamine and inhibits serotonin release. We show voltammetrically, mathematically, and pharmacologically that this serotonin inhibition is H3 receptor mediated.

In vivo histamine voltammetry in the mouse premammillary nucleus

Histamine plays a major role in the mediation of allergic reactions such as peripheral inflammation. This classical monoamine is also a neurotransmitter involved in the central nervous system but its role in this context is poorly understood. Studying histamine neurotransmission is important due to its implications in many neurological disorders. The sensitivity, selectivity and high temporal resolution of fast scan cyclic voltammetry (FSCV) offer many advantages for studying electroactive neurotransmitters. Histamine has previously been studied with FSCV; however, the lack of a robust Faradaic electrochemical signal makes it difficult to selectively identify histamine in complex media, as found in vivo. In this work, we optimize an electrochemical waveform that provides a stimulation-locked and unique electrochemical signal towards histamine. We describe in vitro waveform optimization and a novel in vivo physiological model for stimulating histamine release in the mouse premammillary nucleus via stimulation of the medial forebrain bundle. We demonstrate that a robust signal can be used to effectively identify histamine and characterize its in vivo kinetics.

Intrinsic and inducible resistance to hydrogen peroxide in Bifidobacterium species

Interest in, and use of, bifidobacteria as a probiotic delivered in functional foods has increased dramatically in recent years. As a result of their anaerobic nature, oxidative stress can pose a major challenge to maintaining viability of bifidobacteria during functional food storage. To better understand the oxidative stress response in two industrially important bifidobacteria species, we examined the response of three strains of B. longum and three strains of B. animalis subsp. lactis to hydrogen peroxide (H₂O₂). Each strain was exposed to a range of H₂O₂ concentrations (0-10 mM) to evaluate and compare intrinsic resistance to H₂O₂. Next, strains were tested for the presence of an inducible oxidative stress response by exposure to a sublethal H₂O₂ concentration for 20 or 60 min followed by challenge at a lethal H₂O₂ concentration. Results showed B. longum subsp. infantis ATCC 15697 had the highest level of intrinsic H₂O₂ resistance of all strains tested and B. animalis subsp. lactis BL-04 had the highest resistance among B. lactis strains. Inducible H₂O₂ resistance was detected in four strains, B. longum NCC2705, B. longum D2957, B. lactis RH-1, and B. lactis BL-04. Other strains showed either no difference or increased sensitivity to H₂O₂ after induction treatments. These data indicate that intrinsic and inducible resistance to hydrogen peroxide is strain specific in B. longum and B. lactis and suggest that for some strains, sublethal H₂O₂ treatments might help increase cell resistance to oxidative damage during production and storage of probiotic-containing foods.

Evaluation of the triangular cord sign in the diagnosis of biliary atresia

BACKGROUND

Infantile cholestasis continues to represent a diagnostic challenge. It is very important to diagnose surgically correctable disorders, such as biliary atresia, in a timely manner to prevent progressive damage to the liver. It has been recently suggested that the triangular cord (TC) sign is a simple and useful tool in the diagnosis of biliary atresia.

METHODS

We prospectively studied 65 infants presenting with conjugated hyperbilirubinemia (age range: 32-161 days). All patients underwent ultrasonographic examination with a 7.0-MHz transducer (Acuson, Mountain View, CA). The TC was defined as a triangular, or tubular, echogenic density seen immediately cranial to the portal vein bifurcation.

RESULTS

The TC sign was identified in 25 infants, and all of them had histologic features suggestive of biliary atresia; the diagnosis was confirmed at surgery by gross morphology of hepatobiliary system, and liver biopsy, with or without intraoperative cholangiogram. Among the 40 patients who did not have the TC sign, 6 had paucity of the intrahepatic bile ducts. Three had alph-1-antitrypsin deficiency, and 31 had neonatal hepatitis. None of the 40 patients who did not have the TC sign developed acholic stools. Seven patients with biliary atresia were followed by ultrasonographic examination for 6 months after the Kasai procedure. The TC sign disappeared in all patients after the surgery; however, the TC sign reappeared in 3 patients who developed progressive cholestasis after the procedure.

CONCLUSION

The TC sign is a simple, timesaving, and reliable diagnostic tool in the evaluation of infants with infantile cholestasis. The TC sign may also prove to be helpful in following patients after hepatoportoenterostomy. We suggest a new diagnostic strategy for patients suspected to have biliary atresia. When the TC sign is visualized, the patient should undergo intraoperative cholangiogram to confirm the diagnosis of biliary atresia, reserving percutaneous liver biopsy for those patients in whom the TC sign could not be detected.

The importance of the perfusion index in the evaluation of captopril renography for transplant renal artery stenosis

Severe renal artery stenosis (RAS) is a relatively uncommon complication following renal transplantation but is a curable cause of hypertension which demands reliable early diagnosis to reduce morbidity, mortality and graft loss. Captopril renography has been used for a number of years as a method of detecting RAS mainly in native kidneys, with only a few studies concerning the transplant situation. Controversy still exists as to the diagnostic accuracy of this test and as to the most appropriate interpretation criteria with which to establish a positive result. This paper reports the evaluation of 26 captopril renography investigations on hypertensive renal transplant patients with a suspected diagnosis of RAS. Each renogram study was correlated with an arteriogram as the 'gold standard' which was undertaken within 28 days of the renography. A sensitivity of 92%, a specificity of 86% and an accuracy of 88% were achieved by including a consideration of the change in perfusion to the kidney between pre- and post-challenge studies. It is concluded that captopril renography is a useful screening test for the detection of transplant renal artery stenosis (TRAS).

[Comparative effectiveness of class I anti-arrhythmia drugs and the algorithms of their selection in patients with ventricular arrhythmia]

The efficacy of 7 well-known Class I antiarrhythmic agents were retrospectively and by+crossover compared in 2 groups of patients treated in hospital in different years for ventricular arrhythmias. Class IC agents proved to be the most potent in the two groups of patients. The following algorithm is proposed to choose Class I agents: if quinidine or mexiletine is beneficial in the same patients, the other drugs will be also effective. If disopyramide fails to be beneficial, allapinin , ethacizine , propaphenon will be the most effective. When allapinin produces effects, ethacizine and propaphenon show their highest potency, but when each of them fails, a combination of antiarrhythmic agents should be used.

Immunogenetic study of the response to streptococcal carbohydrate antigen of the cell wall in rheumatic fever

An immunogenetic study of the response to streptococcal carbohydrate antigen of the cell wall was carried out on members of 15 multiplex families each having more than one sib affected with rheumatic heart disease. They comprised 30 parents and 61 sibs (32 with rheumatic disease and 29 without). Fifty healthy unrelated subjects served as controls. A history was taken and clinical examination carried out. Rheumatic activity was determined and HLA typing was carried out for nine A antigens, 15 B antigens, and six DR antigens. The immune response of lymphocytes to streptococcal polysaccharide antigen of the cell wall of group A beta haemolytic streptococci in vitro was studied by tritiated thymidine uptake. The results were statistically and genetically analysed. It was found that (a) all subjects with rheumatic disease were highly responsive to the streptococcal polysaccharide antigen of the cell wall, the sib pairs being mostly HLA identical; (b) all low responders had no rheumatic disease and their phenotypes were mostly different from those of the rheumatic member of their sib pair; (c) correlation of immune responsiveness (high or low) between HLA-identical sibs was significant, but insignificant between haplotype identical and non-identical sibs; (d) the gene responsible for high responsiveness to the streptococcal polysaccharide antigen of the cell wall is recessive and closely linked to HLA. In conclusion, it was found that exposure to pharyngeal infection with group A beta haemolytic streptococci may lead to acute rheumatic fever in those with an inherited recessive gene responsible for high responsiveness to the streptococcal polysaccharide antigen of the cell wall.

[Anti-arrhythmia effect of prolecophen in patients with extrasystole in comparison with other anti-arrhythmia drugs]

Oral prolecohen (LEK, Yugoslavia) was given in a single dose of 300 mg to 15 patients with extrasystole of various genesis. The drug produced an antiarrhythmic effect in 50% of patients with ventricular extrasystole, but in those with supraventricular extrasystole. Prolecophenum showed a good tolerance. In 20% of the patients the adverse reactions appeared as mild headache, dizziness, dry mouth, malaise in the epigastric region. There is also evidence for efficacy of other antiarrhythmic agents used in this group of patients.

[Pharmacodynamics of allapinin and its possible adverse effects]

Allapinine (Class IC), a new antiarrhythmic agent, was studied in 76 patients with premature contraction. Allapinine was found to be beneficial both in ventricular and supraventricular premature beats. Oral allapinine usually showed its effect 40-60 minutes following its administration, its maximum action being 4-5 hours later, its duration was some 8 hours. The optimal dose of the drug amounted to 75 mg/day. Larger-dose allapinine produced adverse effects, its lower dosage had no antiarrhythmic effect. The drug failed to affect blood pressure, heart rate, QT interval length. The PQ interval and QRS complex were increased. The side effects were dose-dependent. There was a risk of the drug's arrhythmogenic effect.

[Safety of long-term therapy with a combination of various anti-arrhythmia agents]

Safety and the effectiveness of combined therapy of arrhythmia was studied in 27 patients in prolonged (up to 4 months) administration of a combination of medicinal agents specially chosen during pharmacodynamic investigation. The obtained anti-arrhythmic effect was stable and there were no new side effects in prolonged administration of combinations of ethmozine with chinidin, ritmilen, obsidan, cordaron (amiodaron) and of allapinin with chinidin, ritmilen (disopyramide) and obsidan (propronalol). Tolerance to drugs was adequate and the ECG parameters remained unaffected.

[Pharmacokinetics and pharmacodynamics of the new Russian anti-arrhythmia drug allapinin]

Pharmacokinetics of allapinin tablets, used as a single dose, alone or in combination with other antiarrhythmic drugs (cordarone, mexitil, ritmilen) were assessed in 11 patients with frequent extrasystoles. Allapinin pharmacokinetic pattern was basically similar in patients in whom it was very effective and those in whom it had no effect. Combined use of the above-mentioned antiarrhythmic drugs and allapinin did not affect the latter's pharmacokinetic parameters. Allapinin pharmacokinetics can be described using a one-part model.

[The pharmacokinetics and pharmacodynamics of the new Soviet anti-arrhythmia preparation allapinin]

Pharmacokinetics and pharmacodynamics of a new antiarrhythmic drug allapinin was studied in patients with frequent ventricular and supraventricular extrasystoles. The technique of determining allapinin by high performance liquid chromatography is described. Intravenous administration of the drug in a dose of 20 mg was shown to be effective in 50% of patients.

Studies of peripheral blood T lymphocytes in assessment of disease activity in rheumatic fever

The study included three groups of children: (a) 38 with active rheumatic fever (ARF) and active carditis; 21 seen during their first attack and 17 during recurrence of activity, (b) 47 with inactive rheumatic fever (IARF); the period since activity was less than 3 years in 31 cases and more than 3 years in 16 cases. Using monoclonal antibodies and T lymphocyte blast transformation induced by PHA, we found: (1) low total T lymphocytes, helper-inducer cells and helper-inducer/suppressor-cytotoxic ratio which persisted for years; and (2) reduced lymphoblast transformation in active disease.

Immune regulation dysfunction in chronic persistent hepatitis

The study included 19 children diagnosed clinically, biochemically, and by liver biopsy as having chronic persistent hepatitis. The following investigations were carried out: 1. detection of total T-lymphocytes, T-helper, and T-suppressor cells using monoclonal antibodies (OKT3, OKT4 and OKT8); 2. determination of HLA-A, B and DR antigens using the microcytotoxicity technique. The results were analysed in comparison with data from a normal control group. There are several important findings. First, low total T-lymphocytes with increased proportion of suppressor cells (P less than 0.001). Second, strong association between HLA-A1 antigen and CPH (Fisher exact = 0.000022). Third, significant association between the immunoregulatory dysfunction and A1 antigen (Fisher exact = 0.033). This observation suggests that a genetic component may influence susceptibility to CPH through an increased suppressor response.