Big Multiple Sclerosis Data network: an international registry research network

BACKGROUND

The Big Multiple Sclerosis Data (BMSD) network ( https://bigmsdata.org ) was initiated in 2014 and includes the national multiple sclerosis (MS) registries of the Czech Republic, Denmark, France, Italy, and Sweden as well as the international MSBase registry. BMSD has addressed the ethical, legal, technical, and governance-related challenges for data sharing and so far, published three scientific papers on pooled datasets as proof of concept for its collaborative design.

DATA COLLECTION

Although BMSD registries operate independently on different platforms, similarities in variables, definitions and data structure allow joint analysis of data. Certain coordinated modifications in how the registries collect adverse event data have been implemented after BMSD consensus decisions, showing the ability to develop together.

DATA MANAGEMENT

Scientific projects can be proposed by external sponsors via the coordinating centre and each registry decides independently on participation, respecting its governance structure. Research datasets are established in a project-to-project fashion and a project-specific data model is developed, based on a unifying core data model. To overcome challenges in data sharing, BMSD has developed procedures for federated data analysis.

FUTURE PERSPECTIVES

Presently, BMSD is seeking a qualification opinion from the European Medicines Agency (EMA) to conduct post-authorization safety studies (PASS) and aims to pursue a qualification opinion also for post-authorization effectiveness studies (PAES). BMSD aspires to promote the advancement of real-world evidence research in the MS field.

Predictors of treatment switching in the Big Multiple Sclerosis Data Network

Background

Treatment switching is a common challenge and opportunity in real-world clinical practice. Increasing diversity in disease-modifying treatments (DMTs) has generated interest in the identification of reliable and robust predictors of treatment switching across different countries, DMTs, and time periods.

Objective

The objective of this retrospective, observational study was to identify independent predictors of treatment switching in a population of relapsing-remitting MS (RRMS) patients in the Big Multiple Sclerosis Data Network of national clinical registries, including the Italian MS registry, the OFSEP of France, the Danish MS registry, the Swedish national MS registry, and the international MSBase Registry.

Methods

In this cohort study, we merged information on 269,822 treatment episodes in 110,326 patients from 1997 to 2018 from five clinical registries. Patients were included in the final pooled analysis set if they had initiated at least one DMT during the relapsing-remitting MS (RRMS) stage. Patients not diagnosed with RRMS or RRMS patients not initiating DMT therapy during the RRMS phase were excluded from the analysis. The primary study outcome was treatment switching. A multilevel mixed-effects shared frailty time-to-event model was used to identify independent predictors of treatment switching. The contributing MS registry was included in the pooled analysis as a random effect.

Results

Every one-point increase in the Expanded Disability Status Scale (EDSS) score at treatment start was associated with 1.08 times the rate of subsequent switching, adjusting for age, sex, and calendar year (adjusted hazard ratio [aHR] 1.08; 95% CI 1.07-1.08). Women were associated with 1.11 times the rate of switching relative to men (95% CI 1.08-1.14), whilst older age was also associated with an increased rate of treatment switching. DMTs started between 2007 and 2012 were associated with 2.48 times the rate of switching relative to DMTs that began between 1996 and 2006 (aHR 2.48; 95% CI 2.48-2.56). DMTs started from 2013 onwards were more likely to switch relative to the earlier treatment epoch (aHR 8.09; 95% CI 7.79-8.41; reference = 1996-2006).

Conclusion

Switching between DMTs is associated with female sex, age, and disability at baseline and has increased in frequency considerably in recent years as more treatment options have become available. Consideration of a patient's individual risk and tolerance profile needs to be taken into account when selecting the most appropriate switch therapy from an expanding array of treatment choices.

The impact of healthcare systems on the clinical diagnosis and disease-modifying treatment usage in relapse-onset multiple sclerosis: a real-world perspective in five registries across Europe

Introduction

Prescribing guidance for disease-modifying treatment (DMT) in multiple sclerosis (MS) is centred on a clinical diagnosis of relapsing-remitting MS (RRMS). DMT prescription guidelines and monitoring vary across countries. Standardising the approach to diagnosis of disease course, for example, assigning RRMS or secondary progressive MS (SPMS) diagnoses, allows examination of the impact of health system characteristics on the stated clinical diagnosis and treatment access.

Methods

We analysed registry data from six cohorts in five countries (Czech Republic, Denmark, Germany, Sweden and United Kingdom) on patients with an initial diagnosis of RRMS. We standardised our approach utilising a pre-existing algorithm (DecisionTree, DT) to determine patient diagnoses of RRMS or secondary progressive MS (SPMS). We identified five global drivers of DMT prescribing: Provision, Availability, Funding, Monitoring and Audit, data were analysed against these concepts using meta-analysis and univariate meta-regression.

Results

In 64,235 patients, we found variations in DMT use between countries, with higher usage in RRMS and lower usage in SPMS, with correspondingly lower usage in the UK compared to other registers. Factors such as female gender (p = 0.041), increasing disability via Expanded Disability Status Scale (EDSS) score (p = 0.004), and the presence of monitoring (p = 0.029) in SPMS influenced the likelihood of receiving DMTs. Standardising the diagnosis revealed differences in reclassification rates from clinical RRMS to DT-SPMS, with Sweden having the lowest rate Sweden (Sweden 0.009, range: Denmark 0.103 - UK portal 0.311). Those with higher EDSS at index (p < 0.03) and female gender (p < 0.049) were more likely to be reclassified from RRMS to DT-SPMS. The study also explored the impact of diagnosis on DMT usage in clinical SPMS, finding that the prescribing environment and auditing practices affected access to treatment.

Discussion

This highlights the importance of a healthcare system's approach to verifying the clinical label of MS course in facilitating appropriate prescribing, with some flexibility allowed in uncertain cases to ensure continued access to treatment.

Natalizumab treatment of multiple sclerosis - a Danish nationwide study with 13 years of follow-up

BACKGROUND

Natalizumab is a widely used high-efficacy treatment in multiple sclerosis (MS). Real-world evidence regarding long-term effectiveness and safety is warranted. We performed a nationwide study evaluating prescription patterns, effectiveness, and adverse events.

METHODS

A nationwide cohort study using the Danish MS Registry. Patients initiating natalizumab between June 2006 and April 2020 were included. Patient characteristics, annualized relapse rates (ARRs), confirmed Expanded Disability Status Scale (EDSS) score worsening, MRI activity (new/enlarging T2- or gadolinium-enhancing lesions), and reported adverse events were evaluated. Further, prescription patterns and outcomes across different time periods ("epochs") were analysed.

RESULTS

In total, 2424 patients were enrolled, with a median follow-up time of 2.7 years (interquartile range (IQR) 1.2-5.1). In recent epochs, patients were younger, had lower EDSS scores, had fewer pre-treatment relapses and were more often treatment naïve. At 13 years of follow-up, 36% had a confirmed EDSS worsening. On-treatment ARR was 0.30, corresponding to a 72% reduction from pre-initiation. MRI activity was rare, 6.8% had activity within 2-14 months from treatment start, 3.4% within 14-26 months, and 2.7% within 26-38 months. Approximately 14% of patients reported adverse events, with cephalalgia constituting the majority. During the study, 62.3% discontinued treatment. Of these, the main cause (41%) was due to JCV antibodies, while discontinuations due to disease activity (9%) or adverse events (9%) were less frequent.

CONCLUSION

Natalizumab is increasingly used earlier in the disease course. Most patients treated with natalizumab are clinically stable with few adverse events. JCV antibodies constitute the main cause for discontinuation.

Proportion and characteristics of secondary progressive multiple sclerosis in five European registries using objective classifiers

Background

To assign a course of secondary progressive multiple sclerosis (MS) (SPMS) may be difficult and the proportion of persons with SPMS varies between reports. An objective method for disease course classification may give a better estimation of the relative proportions of relapsing-remitting MS (RRMS) and SPMS and may identify situations where SPMS is under reported.

Materials and methods

Data were obtained for 61,900 MS patients from MS registries in the Czech Republic, Denmark, Germany, Sweden, and the United Kingdom (UK), including date of birth, sex, SP conversion year, visits with an Expanded Disability Status Scale (EDSS) score, MS onset and diagnosis date, relapses, and disease-modifying treatment (DMT) use. We included RRMS or SPMS patients with at least one visit between January 2017 and December 2019 if ≥ 18 years of age. We applied three objective methods: A set of SPMS clinical trial inclusion criteria ("EXPAND criteria") modified for a real-world evidence setting, a modified version of the MSBase algorithm, and a decision tree-based algorithm recently published.

Results

The clinically assigned proportion of SPMS varied from 8.7% (Czechia) to 34.3% (UK). Objective classifiers estimated the proportion of SPMS from 15.1% (Germany by the EXPAND criteria) to 58.0% (UK by the decision tree method). Due to different requirements of number of EDSS scores, classifiers varied in the proportion they were able to classify; from 18% (UK by the MSBase algorithm) to 100% (the decision tree algorithm for all registries). Objectively classified SPMS patients were older, converted to SPMS later, had higher EDSS at index date and higher EDSS at conversion. More objectively classified SPMS were on DMTs compared to the clinically assigned.

Conclusion

SPMS appears to be systematically underdiagnosed in MS registries. Reclassified patients were more commonly on DMTs.

Real-world experience of cladribine treatment in relapsing-remitting multiple sclerosis: A Danish nationwide study

BACKGROUND

Cladribine is a nucleoside analogue interfering with synthesis and repair of DNA. Treatment with cladribine leads to a preferential reduction in lymphocytes, resulting in profound depletion of B-cells with a rapid recovery of naïve B-cells, while T-cell show a lesser but long-lasting depletion It is approved for treatment of relapsing multiple sclerosis (MS). Cladribine tablets 3.5 mg/kg bodyweight are administered in two yearly treatment courses, each including two treatment series lasting 4 or 5 days, one at the start of the first month and the other at the start of the second month.

OBJECTIVE

To describe treatment patterns of cladribine in a real-world setting.

METHODS

Registry based observational cohort study with prospectively enrolled cases from December 2017 through June 2021. The data source is The Danish Multiple Sclerosis Registry, which is a near complete nationwide population-based registry. Outcomes were length of the treatment, preceding and following treatments, treatment response, and safety data.

RESULTS

In total 268 patients had started therapy with cladribine tablets, 89 men and 179 women, with a median age of 40 years (interquartile range (IQR) 32-48. The disease course was relapsing-remitting MS in 97.8% of the patients, and at treatment start the median time from disease onset was 8.1 years (IQR 4.2-14.5) and EDSS 2.5 (IQR 1.5-3.5). Thirty-four patients (12.7%) were treatment naïve while 56 (20.9%) had received one previous disease-modifying therapy (DMT), 67 (25.0%) two, and 111 (41.4%) three or more previous DMTs. In total, 214 (80.0%) patients had completed the full treatment of two courses of cladribine, while 54 (20.0%) had received only one course of cladribine tablets. The median follow-up time after cladribine initiation was 34.7 months (IQR 23.3-43.7). Compared with an annualized relapse rate (ARR) of 0.67 (95% CI [0.56, 0.79]) in the year prior to start of cladribine, ARR was reduced to 0.11 (95% CI [0.08, 0.15]) in year 0-2 after 3-month re-baseline with cladribine (84.8% reduction). Adverse events, reported in 44 (16.4%) of the patients, were mild or moderate, and herpes zoster was only reported in 2 patients. In total, 30 (11.2%) patients discontinued cladribine treatment, of whom 7 (2.6%) discontinued because of adverse effects and 12 (4.5%) discontinued because of disease activity.

CONCLUSION

In this nationwide review of all Danish patients starting therapy with cladribine tablets in a real-world setting, cladribine treatment was safe, and the therapeutic response was as expected from previous clinical trials. A prolonged observation period is necessary to assess the long-term benefit and risk of cladribine.

Changes in prognosis of the Danish multiple sclerosis population over time

BACKGROUND

The course of multiple sclerosis (MS) appears to be milder in recent decades.

OBJECTIVE

To investigate how time from onset to disability milestones and how demographic and clinical characteristics have changed through subsequent onset cohorts of patients with MS.

METHODS

In the nationwide Danish Multiple Sclerosis Registry, we have registered all 13,562 Danish patients with onset of MS or clinically isolated syndrome from 1996 through 2020. For the analyses of prognosis, we used all cases with relapsing onset (N = 11,669). After stratification into 5-year onset cohorts, we computed the hazard ratios for disability endpoints for all cohorts having at least 10 years of follow-up and the oldest 1996-2000 onset cohort as reference.

RESULTS

Patients in more recent MS onset cohorts have a shorter diagnostic delay and more of them start disease-modifying treatment within 1 year since diagnosis. The prognosis was better for later onset cohorts. For the 2001-2005 cohort, the hazard ratio for confirmed Expanded Disability Status Scale (EDSS) 4 was 0.85 (95% confidence interval (CI), 0.76-0.95) and for confirmed EDSS 6: 0.76 (95% CI, 0.65-0.88). For the more recent 2006-2010 cohort, the corresponding hazard ratios were 0.70 (95% CI, 0.62-0.79) and 0.60 (95% CI, 0.50-0.71).

CONCLUSION

We observed a considerable improvement of the prognosis in recent onset cohorts of relapsing-onset MS.

Ocrelizumab treatment in multiple sclerosis: A Danish population-based cohort study

BACKGROUND AND PURPOSE

Real-world evidence regarding the effectiveness and safety of ocrelizumab for the treatment of multiple sclerosis (MS) is limited. The aim was to evaluate the effectiveness and safety of ocrelizumab treatment for MS in a real-world setting.

METHODS

A nationwide population-based cohort study was conducted where clinical and magnetic resonance imaging data of MS patients enrolled prospectively in the Danish Multiple Sclerosis Registry who initiated ocrelizumab treatment between January 2018 and November 2020 were analyzed.

RESULTS

A total of 1104 patients (85.7% relapsing-remitting MS [RRMS], 8.8% secondary progressive MS [SPMS], 5.5% primary progressive MS [PPMS]) were included, with a median follow-up period of 1.3 years. At baseline, the mean age was 41.4 years in the RRMS group, 44.5 years in the PPMS group and 50.3 years in the SPMS group. Median Expanded Disability Status Scale score was 2.5, 3.5 and 5.5, respectively. Most RRMS and SPMS patients had received previous disease-modifying therapies (87.5% and 91.8%, respectively), whereas PPMS patients were mostly treatment naïve (78.7%). After ocrelizumab initiation, 9.3% of the patients experienced a relapse and 8.7% a 24 weeks confirmed disability worsening. Conversely, 16.7% showed a 24 weeks confirmed disability improvement. After ~1 year of treatment, most patients (94.5%) were free of magnetic resonance imaging activity. Ocrelizumab was generally well tolerated, as side effects were only reported for 10% of patients, mostly consisting of infusion-related reactions and infections.

CONCLUSIONS

It is shown that most MS patients treated with ocrelizumab are clinically stabilized and with an adverse event profile consistent with the experience from the pivotal clinical trials.

Treatment Escalation vs Immediate Initiation of Highly Effective Treatment for Patients With Relapsing-Remitting Multiple Sclerosis: Data From 2 Different National Strategies

Importance

Treatment strategies for relapsing-remitting multiple sclerosis (RRMS) vary markedly between Denmark and Sweden. The difference in the association of these national strategies with clinical outcomes is unknown.

Objective

To investigate the association of national differences in disease-modifying treatment (DMT) strategies for RRMS with disability outcomes.

Design, Setting, and Participants

This cohort study used data on 4861 patients from the Danish and Swedish national multiple sclerosis (MS) registries from the date of index DMT initiation (between January 1, 2013, and December 31, 2016) until the last recorded visit at time of data extraction (October 2, 2019).

Exposures

All MS-specific DMTs initiated during the observation period were included in the analysis.

Main Outcomes and Measures

The primary study outcome was time to 24-week confirmed disability worsening. Secondary outcomes were 24-week confirmed disability improvement, milestone Expanded Disability Status Scale scores of 3 and 4, annualized relapse rate, time to first relapse, and treatment switching. Data were analyzed using inverse probability of treatment weighting-based models using a propensity score to weight and correct the comparison for the imbalance of confounders observed at baseline between the 2 countries.

Results

A total of 2700 patients from the Swedish MS registry (1867 women [69.2%]; mean [SD] age, 36.1 [9.5] years) and 2161 patients from the Danish MS registry (1472 women [68.1%]; mean [SD] age, 37.3 [9.4 years]) started a first DMT between 2013 and 2016, were included in the analysis, and were observed for a mean (SD) of 4.1 (1.5) years. A total of 1994 Danish patients (92.3%) initiated a low to moderately effective DMT (teriflunomide, 907 [42.0%]) and 165 (7.6%) initiated a highly effective DMT, whereas a total of 1769 Swedish patients (65.5%) initiated a low to moderately effective DMT (teriflunomide, 64 [2.4%]) and 931 (34.5%) initiated a highly effective DMT. The Swedish treatment strategy was associated with a 29% reduction in the rate of postbaseline 24-week confirmed disability worsening relative to the Danish treatment strategy (hazard ratio, 0.71; 95% CI, 0.57-0.90; P = .004). The Swedish treatment strategy was also associated with a 24% reduction in the rate of reaching an expanded disability status scale score of 3 (hazard ratio, 0.76; 95% CI, 0.60-0.97; P = .03) and a 25% reduction in the rate of reaching an expanded disability status scale score of 4 (hazard ratio, 0.75; 95% CI, 0.61-0.96; P = .01) relative to Danish patients.

Conclusions and Relevance

The findings of this study suggest that there is an association between differences in treatment strategies for RRMS and disability outcomes at a national level. Escalation of treatment efficacy was inferior to using more efficacious DMT as initial treatment.

Age and sex as determinants of treatment decisions in patients with relapsing-remitting MS

BACKGROUND

. Most patients with relapsing-remitting multiple sclerosis (RRMS) are initially treated with moderate efficacy disease-modifying therapies (meDMTs), and only a smaller group of highly active patients are initiated on a high efficacy disease-modifying therapy (heDMT). Real-world data have shown that choosing a heDMT as the initial therapy in highly active RRMS patients is more effective than using a meDMT, and that in patients with breakthrough disease on a meDMT escalation of treatment to a heDMT is more effective than staying on the same or switching to another meDMT. The role of age and sex as determinants for selection of the initial treatment intensity, and for using escalation of treatment intensity in patients with relapse activity on treatment with meDMTs, is only partially known.

METHODS

. We included all Danish patients with RRMS registered in The Danish Multiple Sclerosis Registry who began a DMT since 2014 and stratified the cohort according to sex and age < 40 and ≥ 40 years at first DMT treatment. We studied determinants, with emphasis on age and sex, for the primary choice of therapy, for adherence to the initial therapy and for treatment escalation. Based on existing literature and clinical relevance, we included the following potential confounders in the analyses: DMT efficacy, pre-treatment relapse activity, disease duration, Expanded Disability Status Scale (EDSS) score, and, in a subgroup, MRI activity.

RESULTS

. With all covariates mutually adjusted, patient age was a strong decisive factor for choosing a heDMT with odds ratio 1.69 for starting a heDMT in patients < 40 years compared with patients ≥ 40 years. Men had odds ratio 1.53 for starting with a heDMT compared with women. The odds ratio of heDMT in patients with EDSS > 3 vs ≤ 3 was 3.49, and every additional relapse was associated with increased odds ratio 2.33 for heDMT. Patients were more adherent to the initial heDMTs than to the initial meDMTs. Patients above 40 years were more prone to stay on the initial treatment compared to patients below 40, regardless of whether the initial treatment was meDMT (p<0.001) or heDMT (p=0.008) (covariates mutually adjusted). Relapse activity resulted in escalation of therapy to a heDMT in 67% of patients aged < 40 years (N=273) and in 56% patients aged 40 years or above (N=159) (p=0.008), and younger patients had odds ratio 1.46 of escalating therapy compared to older patients. Male patients were more likely to have treatment escalation to heDMTs than female patients (odds ratio 2.03).

CONCLUSION

. Age and sex appear to be independent determinants for the choice of the initial DMT and for the decision of treatment escalation in patients with breakthrough disease on a meDMT. It is unfortunate, if older age is a factor that make choice of a heDMT more unlikely, as many DMTs seems to be less efficacious in older patients.

The Danish Multiple Sclerosis Registry

OBJECTIVES

The Danish Multiple Sclerosis Registry is the oldest operative and nationwide MS registry. We present The Danish Multiple Sclerosis Registry with its history, data collection, scientific contribution, and national and international research collaboration.

MATERIALS AND METHODS

Detailed description of data collection, completeness, quality optimizing procedures, funding, and legal, ethical and data protection issues are provided.

RESULTS

The total number of registered cases with clinical isolated syndrome and multiple sclerosis since 1956 was by start of May 2020 30,023 of whom 16,515 cases were alive and residing in Denmark, giving a prevalence rate of about 284 per 100,000 population. The mean annual number of new cases receiving an MS diagnosis was 649 per year in the period 2010 to 2019. In total, 7,945 patients (48.1%) are receiving disease modifying therapy at the start of May 2020.

CONCLUSIONS

Multiple Sclerosis registers are becoming increasingly important, not only for epidemiological research but also by quantifying the burden of the disease for the patients and society and helping health care providers and regulators in their decisions. The Danish Multiple Sclerosis Registry has served as data source for a number of scientific publications including epidemiological studies on changes in incidence and mortality, cohort studies investigating risk factors for developing MS, comorbidities and socioeconomic outcomes in the MS population, and observational studies on effectiveness of disease modifying treatments outside the narrow realms of randomized clinical trials.

Distinction among North Atlantic cod Gadus morhua stocks by tissue fatty acid profiles

The fatty acid (FA) profiles of the white muscle and heart tissues of cod Gadus morhua from five locations, Faroe Bank, Faroe Plateau, North-West Iceland, Norway-Barents Sea and Denmark-Skagerrak, were population dependent. The interregional differences of FAs were significantly dissimilar (P < 0.01) in most cases. By way of a rapid and simple analytical method, the stock dependence and harvest location of individual G. morhua were chemometrically determined by multivariate principal component analysis. The difference among the stocks was correlated with the average water temperature at the harvest locations. It thus appears that the tissue FA profile is a phenotypic trait that is partly temperature driven.

Lactate concentrations in the rectal lumen in patients in early septic shock

BACKGROUND

Previously, we observed that rectal luminal lactate was higher in non-survivors compared with survivors of severe sepsis or septic shock persisting >24 h. The present study was initiated to further investigate this tentative association between rectal luminal lactate and mortality in a larger population of patients in early septic shock.

METHODS

A prospective observational multicentre study of 130 patients with septic shock at six general ICU's of university hospitals. Six to 24 h after the onset of septic shock, the concentration of lactate in the rectal lumen was estimated by a 4-h equilibrium dialysis. Dialysate concentrations of lactate were determined using an auto-analyser.

RESULTS

The overall 30-day mortality was 32%, with age and Simplified acute physiology scores II and sequential organ failure assessment scores being significantly higher in non-survivors. In contrast, there were no differences in concentrations of lactate in the rectal lumen [2.2 (1.4-4.1) and 2.8 (1.6-5.1) mmol/l (P=0.34)] (medians and 25th-75th percentiles) or arterial blood [2.1 (1.4-4.2) and 2.0 (1.3-3.2) mmol/l (P=0.15)] between non-survivors and survivors. The rectal-arterial difference of the lactate concentration was higher in survivors. There were no differences in blood pressure, noradrenaline dose or central venous oxygen saturation between the groups.

CONCLUSION

In this prospective, observational study of unselected patients with early septic shock, there was no difference in the concentration of lactate in the rectal lumen between non-survivors and survivors.

TRIAL REGISTRATION

Clinicaltrials.gov (no: NCT00197938).

Opioid action on respiratory neuron activity of the isolated respiratory network in newborn rats

BACKGROUND

Underlying mechanisms behind opioid-induced respiratory depression are not fully understood. The authors investigated changes in burst rate, intraburst firing frequency, membrane properties, as well as presynaptic and postsynaptic events of respiratory neurons in the isolated brainstem after administration of opioid receptor agonists.

METHODS

Newborn rat brainstem-spinal cord preparations were used and superfused with mu-, kappa-, and delta-opioid receptor agonists. Whole cell recordings were performed from three major classes of respiratory neurons (inspiratory, preinspiratory, and expiratory).

RESULTS

Mu- and kappa-opioid receptor agonists reduced the spontaneous burst activity of inspiratory neurons and the C4 nerve activity. Forty-two percent of the inspiratory neurons were hyperpolarized and decreased in membrane resistance during opioid-induced respiratory depression. Furthermore, under synaptic block by tetrodotoxin perfusion, similar changes of inspiratory neuronal membrane properties occurred after application of mu- and kappa-opioid receptor agonists. In contrast, resting membrane potential and membrane resistance of preinspiratory and majority of expiratory neurons were unchanged by opioid receptor agonists, even during tetrodotoxin perfusion. Simultaneous recordings of inspiratory and preinspiratory neuronal activities confirmed the selective inhibition of inspiratory neurons caused by mu- and kappa-opioid receptor agonists. Application of opioids reduced the slope of rising of excitatory postsynaptic potentials evoked by contralateral medulla stimulation, resulting in a prolongation of the latency of successive first action potential responses.

CONCLUSIONS

Mu- and kappa-opioid receptor agonists caused reduction of final motor outputs by mainly inhibiting medullary inspiratory neuron network. This inhibition of inspiratory neurons seems to be a result of both a presynaptic and postsynaptic inhibition. The central respiratory rhythm as reflected by the preinspiratory neuron burst rate was essentially unaltered by the agonists.

The redfish species Sebastes viviparus, Sebastes marinus and Sebastes mentella have different composition of their tissue fatty acids

The fatty acid profile in the tissue of heart, gill, skull- and otolith-oil of the three redfish species, Sebastes viviparus, S. marinus and S. mentella was determined by a chemometric method, consisting of methanolysis of samples of the tissues and of the oils and gas chromatography of the resulting fatty acid methyl esters. The analytical data were treated by multivariate statistics comprising principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). Although the differences in fatty acid composition among the two tissues and two oils were the dominating features of the data, the three species had significantly different fatty acid profiles within each tissue. Variation among the individuals was considerable. The fatty acid profiles appeared to be species specific. The mutual relationship between S. marinus and S. mentella is closer than the relationship between either of them and S. viviparus. A comparison with a corresponding investigation on the same three species from another location indicates that the observed differences do not seem to be affected by biotic or abiotic factors.

Isoflurane does not depress the hypoxic response of rabbit carotid body chemoreceptors

Whether volatile anesthetics have an effect on the peripheral chemoreceptors is controversial, possibly because of differences in end-tidal CO(2) concentrations. We studied the effect of isoflurane on the hypoxic chemosensitivity of carotid body chemoreceptors at three different PaCO(2) levels before and during the administration of 1.0% isoflurane (0.5 minimum alveolar anesthetic concentration) in six normothermic New Zealand white rabbits anesthetized with thiopental. The response of the chemoreceptors was fitted to the equation: Frequency (Hz) = a + b x PaCO(2) + c x (1/PaO(2)) + Dx (1/PaO(2))(2). Mean values for the coefficients a, b, c and d for the control state were -4.5, 0.13, 771, and 6332, respectively. This relationship was not changed by addition of isoflurane at 1.0% end-tidal concentration (P = 0.40, analysis of variance). We conclude that isoflurane at 1.0% end-tidal concentration does not depress the hypoxic response of rabbit carotid body chemoreceptors during either hypo-, normo-, or hypercapnia.

IMPLICATIONS

By measuring single-fiber chemoreceptor activity in anesthetized rabbits, we showed that isoflurane at 1.0% end-tidal concentration does not depress the hypoxic chemosensitivity of peripheral chemoreceptors during either hypo-, normo-, or hypercapnia in this species.

Discrimination of Sebastes viviparus, Sebastes marinus and Sebastes mentella from Faroe Islands by chemometry of the fatty acid profile in heart and gill tissues and in the skull oil

The composition of fatty acids in the tissue of heart, gill and skull oil of the three redfish species, Sebastes viviparus, Sebastes marinus and Sebastes mentella was determined by a chemometric method. The method consists of methanolysis of samples of the tissues and of the oils, gas chromatography of the resulting fatty acid methyl esters and multivariate statistical treatment, by principal component analysis, of the analytical data. Although the differences in fatty acid composition among the three tissues were the dominating features of the data, the three species had significantly different fatty acid profiles within each tissue, even though variation among the individuals was considerable. The fatty acid profiles appear to be species specific. The mutual relationship between S. marinus and S. mentella is closer than the relationship between either of them and S. viviparus.

Carotid body chemoreceptor function is impaired by vecuronium during hypoxia

BACKGROUND

Neuromuscular blocking agents reduce the human ventilatory response to hypoxia at partial neuromuscular block. It was hypothesized that vecuronium impairs carotid body chemoreceptor function during hypoxia.

METHOD

The effect of systemic administration of vecuronium on single chemoreceptor activity during hypoxia, as recorded from a single nerve fiber preparation of the carotid sinus nerve, was studied in seven mechanically ventilated New Zealand White rabbits during continuous thiopental anesthesia. During normoventilation, the isocapnic hypoxic chemosensitivity of the single carotid body chemoreceptor was measured at four levels of oxygenation; these measurements were repeated at six separate occasions: control recording before injection, after intravenous administrations of 0.1 mg and 0.5 mg of vecuronium, and then at three occasions during a 90-min recovery period. Chemoreceptor chemosensitivity during isocapnic hypoxia was expressed as a hyperbolic function: Chemoreceptor output (Hz) = a + b x PaO2(-1) (mmHg).

RESULTS

Chemosensitivity was reduced after both 0.1 mg and 0.5 mg vecuronium intravenous administration compared with control measurements; the hypoxic response curve was significantly depressed after both doses (P < 0.05). Notably, there was variation in the effect of vecuronium; some chemoreceptor preparations showed only minimal impairment, whereas some showed an almost abolished response to hypoxia. The chemosensitivity remained significantly depressed at 30 and 60 min but had recovered spontaneously at 90 min after 0.5 mg vecuronium.

DISCUSSION

It is concluded that vecuronium depresses carotid body chemoreceptor function to a varying extent during hypoxia and that the depression recovers spontaneously.

Laryngeal mask airway guided tracheal intubation in a neonate with the Pierre Robin syndrome

Endotracheal intubation in infants with the Pierre Robin syndrome may sometimes be impossible to accomplish by conventional means. To aid difficult tracheal intubation many different techniques have been described. We present a case, in which we successfully intubated a small-for-date newborn boy with the Pierre Robin syndrome by using a modified laryngeal mask airway (no. 1) as a guide for the endotracheal tube. The technique is easy to perform, less traumatic and less time-consuming than multiple attempts at laryngoscopy or blind tracheal intubation.