Evaluation of heroin-assisted treatment in Norway: protocol for a mixed methods study

BACKGROUND

Opioid agonist treatment (OAT) for patients with opioid use disorder (OUD) has a convincing evidence base, although variable retention rates suggest that it may not be beneficial for all. One of the options to include more patients is the introduction of heroin-assisted treatment (HAT), which involves the prescribing of pharmaceutical heroin in a clinical supervised setting. Clinical trials suggest that HAT positively affects illicit drug use, criminal behavior, quality of life, and health. The results are less clear for longer-term outcomes such as mortality, level of function and social integration. This protocol describes a longitudinal evaluation of the introduction of HAT into the OAT services in Norway over a 5-year period. The main aim of the project is to study the individual, organizational and societal effects of implementing HAT in the specialized healthcare services for OUD.

METHODS

The project adopts a multidisciplinary approach, where the primary cohort for analysis will consist of approximately 250 patients in Norway, observed during the period of 2022-2026. Cohorts for comparative analysis will include all HAT-patients in Denmark from 2010 to 2022 (N = 500) and all Norwegian patients in conventional OAT (N = 8300). Data comes from individual in-depth and semi-structured interviews, self-report questionnaires, clinical records, and national registries, collected at several time points throughout patients' courses of treatment. Qualitative analyses will use a flexible inductive thematic approach. Quantitative analyses will employ a wide array of methods including bi-variate parametric and non-parametric tests, and various forms of multivariate modeling.

DISCUSSION

The project's primary strength lies in its comprehensive and longitudinal approach. It has the potential to reveal new insights on whether pharmaceutical heroin should be an integral part of integrated conventional OAT services to individually tailor treatments for patients with OUD. This could affect considerations about drug treatment even beyond HAT-specific topics, where an expanded understanding of why some do not succeed with conventional OAT will strengthen the knowledge base for drug treatment in general. Results will be disseminated to the scientific community, clinicians, and policy makers.

TRIAL REGISTRATION

The study was approved by the Norwegian Regional Committee for Medical and Health Research Ethics (REK), ref.nr.:195733.

Who receives heroin-assisted treatment? A comparison of patients receiving opioid maintenance treatment in Denmark

BACKGROUND

Since 2010, heroin-assisted treatment (HAT) has been one of the treatment options available to people with opioid use disorder (OUD) in Denmark. This study aimed to characterize HAT patients at treatment start and compare their individual characteristics to those of patients entering traditional opioid maintenance treatment (OMT) with methadone or buprenorphine during the same period.

METHODS

Patients who initiated HAT or OMT with methadone or buprenorphine in Denmark from 2010 to 2018 were included (n=6798). Multiple national registers were linked to compare treatment groups in terms of socio-demographic variables, previous OUD treatment episodes, hospital-based care, and criminal conviction history.

RESULTS

Nearly all HAT patients had a history of methadone treatment (91%) and half had residential treatment experience (48%). In the year previous to admission, HAT patients recorded the highest percentages of non-fatal overdoses (12%) and chronic hepatitis C diagnoses (16%), and the lowest percentages of psychiatric disorders (11%) compared to traditional OMT patients. Criminal convictions were also common: 39% of the HAT group had committed a property crime and 18% a drug-related crime the year before HAT entry. During the study period, an overall reduction in OMT enrollments for each year was recorded. The HAT proportion to the total remained fairly stable (4%-10%), while the buprenorphine proportion increased.

CONCLUSIONS

In Denmark, OMT patients exhibited numerous vulnerabilities at treatment start, and among the patient groups, HAT patients were the most burdened. HAT seems to reach the target group and adhere to formulated eligibility criteria.

A novel estimate of biological aging by multiple fitness tests is associated with risk scores for age-related diseases

Introduction: Recent research highlights the need for a correct instrument for monitoring the individual health status, especially in the elderly. Different definitions of biological aging have been proposed, with a consistent positive association of physical activity and physical fitness with decelerated aging trajectories. The six-minute walking test is considered the current gold standard for estimating the individual fitness status in the elderly. Methods: In this study, we investigated the possibility of overcoming the main limitations of assessing fitness status based on a single measure. As a result, we developed a novel measure of fitness status based on multiple fitness tests. In 176 Sardinian individuals aged 51-80 years we collected the results of eight fitness tests to measure participants' functional mobility, gait, aerobic condition, endurance, upper and lower limb strength, and static and dynamic balance. In addition, the participants' state of health was estimated through validated risk scores for cardiovascular diseases, diabetes, mortality, and a comorbidity index. Results: Six measures contributing to fitness age were extracted, with TUG showing the largest contribution (beta = 2.23 SDs), followed by handgrip strength (beta = -1.98 SDs) and 6MWT distance (beta = -1.11 SDs). Based on fitness age estimates, we developed a biological aging measure using an elastic net model regression as a linear combination of the results of the fitness tests described above. Our newly developed biomarker was significantly associated with risk scores for cardiovascular events (ACC-AHA: r = 0.61; p = 0.0006; MESA: r = 0.21; p = 0.002) and mortality (Levine mortality score: r = 0.90; p = 0.0002) and outperformed the previous definition of fitness status based on the six-minute walking test in predicting an individual health status. Discussion: Our results indicate that a composite measure of biological age based on multiple fitness tests may be helpful for screening and monitoring strategies in clinical practice. However, additional studies are needed to test standardisation and to calibrate and validate the present results.

Adolescents' Psychoactive Substance Use During the First COVID-19 Lockdown: A Cross Sectional Study in Italy

Background

Italy was one of the first European countries to be affected by Covid-19. Due to the severity of the pandemic, the Italian government imposed a nationwide lockdown which had a great impact on the population, especially adolescents. Distance-learning, moving restrictions and pandemic-related concerns, resulted in a particularly stressful situation.

Objective

This cross-sectional study aims to analyse substance consumption and its associated factors during the Covid-19 lockdown imposed by the Italian government.

Methods

ESPAD is a questionnaire that is administered yearly in Italian high schools. In 2020, it was administered online during dedicated hours of distance learning, collecting data from 6027 Italian students (52.4% were male) aged 15-19. Data collected from the 2020 questionnaire was matched with that collected in 2019, in order to make them comparable.

Results

The prevalence of consumption of each substance decreased during the restriction period, and the most used substance during the lockdown period was alcohol (43.1%). There were some changes in factors associated with psychoactive substance use, especially painkillers and non-prescription drugs. For instance, unlike what was observed in the 2019 model, in 2020 spending money without parental control was associated with painkillers and non-prescription drug use while risk perception was not.

Conclusions

The restrictions and the increased difficulties in obtaining psychoactive substances did not prevent their consumption, and students with particular risk factors continued to use them, possibly changing the substance type of substance. This information is useful in order to better understand adolescents' substance use during the ongoing pandemic.

Is oral antibiotic therapy as effective as intravenous treatment in bacterial osteomyelitis? A real-life experience

OBJECTIVE

Osteomyelitis is a relatively understudied disease with no standardized and evidence-based approach to treatment. We aimed to evaluate a cohort of patients with osteomyelitis, comparing the outcomes between intravenous (IV) and oral treatment.

PATIENTS AND METHODS

We performed an observational retrospective study on osteomyelitis cases in adult patients seen for care between 2017 and 2019. We collected information on patient characteristics, microbiological etiology, infection treatment, and outcome. In addition, we divided osteomyelitis cases by antibiotic regimens [oral (OTG) vs. intravenous±oral (ITG)] and therapy durations to evaluate outcomes differences.

RESULTS

A total of 235 episodes of osteomyelitis were evaluated, with a higher prevalence in male gender. Staphylococci, especially S. aureus, were the most common strains. Out of the 235 evaluated episodes, we selected 142 cases. Of these, 75 were treated with OTG and 67 with ITG. Gram-positive bacteria were the most frequent aetiological agents, with 81 isolates (61.8%). Full recovery was observed in 79 (55.6%) cases; of these, 36 (53.7%) were in the ITG and 43 (57.3%) in the OTG (p = 0.666). At the logistic regression, a polymicrobial infection [OR 4.16 (95%CI 1.28-13.4), p = 0.017] and a less than six weeks treatment duration [OR 4.24 (95%CI 1.38-5.43) p = 0.004] were significantly associated with a higher risk of treatment failure.

CONCLUSIONS

Our study suggests that oral treatment efficacy is comparable to ITG therapy for osteomyelitis, confirming the most recent evidence suggesting that oral therapy is non-inferior to intravenous therapy to treat osteomyelitis.

Organic-Inorganic Hybrid Material Synthesis by on Line Coupling Twin Screw Extruder with a Microwave Oven

A new process for elaborating continuously organic-inorganic hybrid materials by reactive extrusion is presented. This synthesis consists in formulating a copolymer of ethylene and vinyl acetate (EVA)/tetrapropoxysilane (TPOS or Si(OC3H7)4)/catalyst blend by a corotating twin screw extruder followed by two successive reaction steps: on line microwave crosslinking reaction and hydrolysis-condensation reactions leading to a silica network cografted onto the organic matrix.

Extrusion feed rate (Q), temperature, microwave oven power (P), and microwave curing time (tmw) were studied. Crosslinking density was evaluated before and after hydrolysis-condensation reactions and compared with the previous results obtained in static conditions. These materials tailored by an on line process present a permanent elasticity at high temperature (up to 200 °C) and a certain optical transparency. This new approach offers the possibility to synthesize massive samples based on organic-inorganic hybrid material.

Association between circulating osteoblast progenitor cells and aortic calcifications in women with postmenopausal osteoporosis

BACKGROUND AND AIMS

Ectopic artery calcification has been documented in women with postmenopausal osteoporosis, in whom an imbalance in the number of circulating osteoprogenitor cells (OPCs) has been identified. Circulating OPCs form calcified nodules in vitro; however, it remains unknown whether an association exists between the number of circulating OPCs and aortic calcifications. We investigated the relationship between OPCs and aortic calcifications in women with postmenopausal osteoporosis.

METHODS AND RESULTS

The number of circulating OPCs was quantified by FACS analysis in 50 osteoporotic postmenopausal women. OPCs were defined as CD15-/alkaline-phosphatase(AP)+ cells coexpressing or not CD34. Participants underwent measurement of markers of bone metabolism, bone mineral density and abdominal aortic calcium (AAC) by 64-slice computed tomography. Patients with AAC were older, had lower 25(OH)vitamin D levels and higher circulating CD15-/AP+/CD34- cells than those without AAC. Significant correlates of AAC included age (rho = 0.38 p = 0.006), calcium (rho = 0.35 p = 0.01), 25(OH)vitamin D (rho = -0.31, p = 0.03) and the number of CD15-/AP+/CD34- cells (rho = 0.55 p < 0.001). In regression analyses, the log-transformed number of CD15-/AP+/CD34- cells was associated with the presence (OR = 6.45, 95% CI 1.03-40.1, p = 0.04) and severity (β = 0.43, p < 0.001) of AAC, independent of age, 25(OH)vitamin D, calcium and other potential confounders. Patients with low 25(OH)vitamin D and high CD15-/AP+/CD34- cells had higher median AAC than other patients (1927/μL, 862-2714/μL vs 147/μL, 0-1665/μL, p = 0.003).

CONCLUSION

In women with postmenopausal osteoporosis, the number of circulating CD15-/AP+/CD34- cells is significantly associated with increased aortic calcifications, that appear to be correlated also with reduced 25(OH)vitamin D levels.

[Psychopathy and suicidal behaviour in a sample of mentally disordered offenders]

Empirical literature has yielded a positive association between psychopathy levels and suicide attempts. This association is centred around impulsivity and disinhibitory facets of psychopathy, whereas suicide and emotional poverty remain independent. Evidence about the relation between suicide and psychopathy in mentally disordered offenders is not conclusive. The present work explores the relation between several measures of antisocial personality, suicide attempt and deliberate self mutilation in a sample of inmates from a forensic psychiatric hospital. Results support the association between disinhibitory aspects of personality and suicide in this population.

Efficacy of intravenous tramadol treatment for reducing pain during office diagnostic hysteroscopy

OBJECTIVE

To assess whether IV tramadol before outpatient hysteroscopy could reduce procedure-related pain.

DESIGN

A randomized double-blind placebo controlled trial.

SETTING

Outpatient Hysteroscopy Centre in the Department of Obstetrics and Gynaecology of Cagliari University.

PATIENT(S)

Fifty healthy, parous, women who underwent outpatient diagnostic hysteroscopy and endometrial biopsy.

INTERVENTION(S)

Random IV infusion of tramadol or placebo before hysteroscopy and endometrial biopsy were performed.

MAIN OUTCOME MEASURE(S)

Visual analogue scale of pain was measured both immediately after and 15 minutes after the procedure. Stress hormones (ACTH, cortisol), blood pressure, and heart frequency were evaluated before, during, and 15 minutes after the procedure.

RESULT(S)

In the tramadol group, the visual analogue scale of pain was significantly lower than in the placebo group both immediately after the procedure and 15 minutes later. Basal levels of ACTH and cortisol did not differ between the groups. In both groups, the ACTH levels remained unchanged during the study, and the cortisol levels were higher 15 minutes after the procedure than before the procedure. Procedure time, heart frequency, blood pressure, and adverse effects did not differ between the groups.

CONCLUSION(S)

In parous women without uterine malformations, a treatment with tramadol before hysteroscopy and endometrial biopsy appears to be capable of reducing the pain and discomfort that are associated with this procedure.

Poor Reliability of Heart Rate Monitoring to Assess Oxygen Uptake During Field Training

The aim of this study was to quantify the error associated with the assessment of oxygen uptake (VO2) by heart rate (HR) monitoring in 15 athletes freely performing their training session. A laboratory-derived equation was used on the running track to calculate VO2 (VO2est) from HR. Oxygen uptake was also assessed by means of a portable gas analyzer (VO2real). Bland and Altman statistics were carried out in order to evaluate agreement between VO2real and VO2est. The excess in carbon dioxide production (CO2excess) was measured to test the hypothesis that the subject with the highest CO2excess had the highest VO2est - VO2real difference. VO 2real was on average 0.14 l x min (-1) below VO2est. The limits of agreement of this difference were between + 0.77 and - 0.48 l x min (-1). Thus, on average VO2real was overestimated by VO2est. Spearman non-parametric statistics found a significant correlation between CO2excess and VO2est - VO2real difference (R = 0.55, p = 0.031). This study demonstrates that the use of HR monitoring to assess VO2 during field training overestimates VO2real, especially when a substantial increase in CO2excess occurs. Therefore, this method should be used with care when an excessive amount of CO2 is produced as occurs in activities that involve the lactic acid anaerobic source of energy production.

Does reduction of blood prolactin levels reveal the activation of central dopaminergic pathways conveying reward in top athletes?

Prolactin blood levels are modulated directly by CNS via the known tubero-infundibular dopaminergic neurons which exert an inhibitory action on lactotrope cells in the hypophysis. Prolactin is devoid of peripheral negative feedback and via lesser known central pathways (e.g., mesolimbic and mesocortical) might be further tuned by means of appropriate stimuli (e.g., addictive drugs, gambling, exercise and so forth). Therefore, a prolactin test can be utilised to obtain an objective index to assess the compliance to exercise in men. This index may be used to identify the most suitable athlete for a given sport and mainly to survey exercise as rewarding behaviour in trained people. Prolactin was assessed in male top world windsurfers (WS) and in a control group of non-windsurfer trained subjects (CS) during an exercise simulating marine windsurfing. The result was that prolactin levels decreased significantly in WS with respect to CS when compared with pre-test levels (WS: -22.7%; P<0.05).

Persistent neutralizing antibodies abolish the interferon beta bioavailability in MS patients

BACKGROUND

MxA is an antiviral protein exclusively induced by type I interferons (IFN) and some viruses, and MxA gene expression is one of the most appropriate markers for measuring the biologic activity of exogenous IFNbeta.

METHODS

A new quantitative-competitive PCR method was used to quantify MxA mRNA in peripheral blood mononuclear cells of 99 treatment-naïve and 92 IFNbeta-treated patients with MS (22 Avonex, 17 Betaferon, and 53 Rebif-22). Every 3 months, IFNbeta-induced neutralizing antibodies (NAb) were evaluated in sera using a cytopathic effect assay. Three categories of patients were identified: NAb negative (NAb-), persistent NAb positive (NAb+, >or=2 consecutive positive samples), and isolated NAb+ (one positive sample).

RESULTS

Treatment-naïve patients expressed detectable MxA mRNA levels (mean = 36 +/- 32 fg MxA/pg glyceraldehyde-3-phosphate dehydrogenase (GAPDH); range 1 to 160) and an upper normal threshold was established (mean + 3 SD = 132 fg MxA/pg GAPDH). IFNbeta-treated patients exhibited more than 11-fold higher levels (mean = 412 +/- 282 fg MxA/pg GAPDH; range 16 to 1,172). However, 17 patients did not exhibit an increase in MxA mRNA level; 15 of these 17 patients showed a concurrent Nab+ titer. Moreover, 13 were persistent NAb+. Isolated NAb+ patients did not show a decrease in bioavailability of IFNbeta (n = 9; mean = 567 +/- 366 fg MxA/pg GAPDH; range 83 to 1,120). In NAb- patients, bioavailability was comparable among the three different IFNbeta preparations 12 hours after injection.

CONCLUSION

During IFNbeta therapy, the presence of NAb reduced or abolished bioavailability in a relevant percentage of patients. These data could be important for the early detection of patients with MS who are not responsive to IFNbeta therapy.

External mechanical work versus oxidative energy consumption ratio during a basketball field test

BACKGROUND

A field test consisting of 5 continuous runs at the maximum speed possible, playing the ball, starting from the centre line to the basket with a final shot, was studied in order to obtain an index of mechanical work efficiency in basketball players (micro-index=Jmec/Joxy) and evaluate the correlation between micro-index and velocity, acceleration, mechanical power and lactacid anaerobic capacity, respectively.

METHODS

Eight male basketball players were studied; Jmec was the external mechanical work output obtained by means of a video image analysis software which gave the potential and the kinetic translational energies of athletes running and jumping and their velocity, acceleration and mechanical power. By means of a telemetric device (Kosmed K4), for measuring O2 consumption ( VO2), we obtained oxidative work (Joxy). By using this device we also assessed the excess of CO2, which was considered an index of lactacid anaerobic capacity.

RESULTS

Non-parametric Spearman statistics revealed a significant correlation between mu index and mean velocity (p<0.01, r=0.90), acceleration (p<0.05, r=0.78), mechanical power (p<0.05 r=0.76) and CO2 excess (p<0.01, r=0.95). Consequently athletes who had the best index of mechanical efficiency also had the best biomechanical quality and the greatest lactacid anaerobic capacity.

CONCLUSIONS

This study strongly supports the hypothesis that in basketball anaerobic capacity is important in achieving high values of speed, acceleration, mechanical power and endurance velocity.

Differential effects of three interferon betas on neutralising antibodies in patients with multiple sclerosis: a follow up study in an independent laboratory

OBJECTIVE

To evaluate the incidence and the prevalence of neutralising antibodies (NABs) to three interferon beta (IFNbeta) products in patients with multiple sclerosis (MS).

METHODS

Sera were tested from 125 patients with relapsing-remitting MS. Patients were treated with IFNbeta-1b (Betaferon, n = 29) 8 MIU subcutaneously every other day, IFNbeta-1a (Avonex, n = 44) 30 microg intramuscularly once weekly, or IFNbeta-1a (Rebif, n = 36) 22 microg subcutaneously three times weekly for 6 to 18 months. An additional 16 patients were treated with Rebif 22 microg intramuscularly once or twice weekly. NABs were assessed using the cytopathic effect assay before treatment and every three months during treatment. Patients with two or more consecutive positive samples were considered to be persistent NAB positive (NAB+).

RESULTS

At baseline, no patients were NAB+. NABs developed during the first three months of treatment and continued to develop until month 18. Over 18 months of treatment, the risk of being persistent NAB+ was 31% for Betaferon, 15% for Rebif, and 2% for Avonex (Betaferon versus Avonex, p = 0.001; Betaferon versus Rebif, p = 0.19; Rebif versus Avonex, p = 0.04). In all patients with one or more NAB+ samples, the risk of becoming NAB+ was 38% for Betaferon, 18% for Rebif, and 7% for Avonex (Betaferon versus Avonex, p = 0.0007; Betaferon versus Rebif, p = 0.10; Rebif versus Avonex, p = 0.07). At month 18, the prevalence of persistent NAB+ patients was 31.6% for Betaferon, 18.7% for Rebif, and 4% for Avonex. Numbers of NAB+ patients observed were similar with intramuscular Rebif and with subcutaneous Rebif.

CONCLUSION

The three IFNbeta preparations have different degrees of immunogenicity, with Betaferon producing the highest incidence of NABs and Avonex the lowest. These differences should be considered by neurologists when selecting treatment for their patients with MS because NABs can reduce both bioavailability and clinical efficacy of IFNbeta.

Haemodynamics during a complete exercise induced atrioventricular block

The case is reported of an athlete who, during an exercise test, had a complete atrioventricular block without symptoms of cardiac output failure. Heart rate, stroke index, cardiac index, and myocardial contractility were monitored during the episode by an impedance cardiograph. The most important findings of this report are the continuous increase in stroke index, which compensated for the lack of heart rate response, and the normal cardiac index values achieved during the exercise. This stroke index response was mainly due to an increase in myocardial contractility.

Evaluation of bioavailability of three types of IFNbeta in multiple sclerosis patients by a new quantitative-competitive-PCR method for MxA quantification

Intracellular expression of human myxovirus protein A (MxA) is exclusively induced by type I IFNs (IFNalpha,beta,omega) or by some viruses and it is strongly increased under IFN treatment. We set up an internally controlled quantitative-competitive polymerase chain reaction (qc-PCR) that quantifies MxA mRNA expressed in human peripheral blood mononuclear cells (PBMC). Our qc-PCR is accurate because the mean ratio of copy number estimated by qc-PCR to that quantified spectrophotometrically is 1.08+/-0.03, moreover it is repeatable with high sensitivity (1 fg MxA/pg GAPDH). MxA mRNA was tested in 47 Relapsing-Remitting Multiple Sclerosis (RR-MS) untreated patients and in 48 patients treated with one of the 3 IFNbeta licensed for MS (24 with Rebif, 14 with Avonex and 10 with Betaferon). All the 48 treated patients were negative to IFNbeta neutralising antibodies (NABs) as tested in our laboratory using a cytopathic assay (CPE). MxA mRNA levels were detectable in all untreated patients (mean 24+/-18 fg MxA/pg GAPDH) and significantly higher levels were found in all the treated patients 12 h after IFNbeta administration (mean 499+/-325 fg MxA/pg GAPDH); furthermore, the three types of IFNbeta showed comparable bioavailability. Our data indicate that the bioavailability of the three available types of IFNbeta can be evaluated by MxA qc-PCR.

Frequency-dependent LTP/LTD in guinea pig Deiters' nucleus

Synaptic plasticity was studied in the lateral vestibular nuclei (LVN) of the guinea pig in vivo. High frequency stimulation (HFS) of increasing or decreasing frequencies was applied to the ipsilateral vestibular nerve. Vestibular field potentials (VFPs) and extracellular single unit activity evoked in the LVN by electrical stimulation of the ipsilateral vestibular nerve, were analyzed before and after the application of different protocols of HFS. Results show that the monosynaptic component of the VFPs undergo long-term potentiation (LTP) with stimulation of 100 Hz applied for 20 s lower frequencies, applied for shorter periods, induce only a transient post-tetanic potentiation. This potentiation, although long lasting, is not permanent since it is susceptible of a reversal or cancellation by opposite patterns of HFS that determine a depression or depotentiation of the previously acquired potentiation. The results demonstrate that the plasticity phenomena that take place at the level of the LVN neurons are not steady but undergo continuous adjustment of their sign and gain depending on the variable flow of vestibular information that reach the nuclei from the labyrinthine receptors.

Autonomic nervous system activity and life threatening arrhythmias in experimental epilepsy

In the present study the possible derangement of the autonomic system and its influence in life threatening arrhythmias were analysed during paroxysmal activity. In hemispherectomized rats a paroxysmal activation of the hypothalamic and mesencephalic cardioarrhythmogenic triggers was performed by topical application of penicillin-G. Blood gas parameters and electrical activity of the thalamus, hypothalamus, vagal nerve fibre, ECG and arterial blood pressure were simultaneously monitored in basal conditions and repeated after the appearance of paroxysmal activity. Temporal correlation analysis was carried out. Results showed that during activation of these triggers, the spontaneous vagal nerve fibre activity significantly increased and triggered the appearance of cardiac arrhythmias which could become life threatening and induce animal death when blood gas and electrolytic parameters were simultaneously impaired. These experiments suggest that fatal evolution of the heart impairment is related not only to an autonomic cardiac trigger, but also to a concomitant metabolic derangement, which most likely shares the same autonomic origin.

Neurotoxic effect of lead at low concentrations

The effects of lead exposure at low concentrations were evaluated by studying the post-rotatory nystagmus (PRN) in two groups of rats exposed for 3 months to 50 parts per million (ppm) of sodium acetate and 50 ppm of lead acetate, respectively, in the drinking water. Only animals treated with lead acetate showed changes of the PRN parameters which were significantly related to the concentration of lead in the blood and in brain structures. The patterns of PRN responses were characterized and classified into four types: progressively inhibitory (40%), prematurely inhibitory (25%), late inhibitory (25%), and excitatory-inhibitory (10%). No alterations of the PRN parameters were observed in the animals treated with sodium acetate. The results show that exposure to lead, even at low concentrations, impairs both sensory and motor functions. The findings also point out that the vestibular system and brain stem structures which generate and control the PRN represent targets of the action of this heavy metal. Finally, the results indicate that the evaluation of the vestibulo-ocular-reflex can provide a test suited for the screening of the neurotoxic effects of lead even in the absence of clinical signs typical of lead intoxication.

Hemodynamic during a postexertional asystolia in a healthy athlete: a case study

Hemodynamic events leading to spontaneous postexertional vasovagal syncope are not completely understood because of the lack of beat-to-beat data. We report a case study of a young athlete who undergoes a syncopal episode during the recovery period following a maximal cycle-ergometer test. The episode was monitored by an impedance cardiograph which can gather noninvasively beat-to-beat the flow of heart rate (HR), stroke volume (SV), cardiac output (CO), diastolic filling rate (SV/DT), and myocardial contractility index (PEP/LVET). The most important findings of this report are the dramatic reduction of SV/DT preceding the syncope, the increment of SV together with the reduction of HR preceding and following the syncope, the prompt recovery of CO values after the syncopal episode despite the bradycardia, and the reduction of PEP/LVET after the syncope. This report confirms the importance of active recovery immediately after strenuous exercise and supports the hypothesis that the reduction of SV/DT in the presence of an inotropic stimulation can trigger the vasovagal reaction.

Epileptic discharge of cortical, subcortical and spinal neurons in penicillin induced experimental epilepsy

The sensitivity and electrophysiological patterns of paroxysmal activity induced in different brain structures by topical application of penicillin-G were evaluated in the rat. Recordings were carried out in five groups of animals, in telencephalon, diencephalon, mesencephalon, rombencephalon and spinal cords. The following analysis were carried out: frequency distribution histograms, latency and time course duration of paroxysmal activity, duration and amplitude of epileptic bursts. The results obtained showed that the nervous structures tested with penicillin-G had a different epileptogenic sensitivity and response pattern which significantly changed along the cerebral cortex-spinal cord axis. The highest epileptic sensitivity was observed in somatosensory cortex (SI) at 500-600 microns depth; in the other cortical layers, a significant lenghtening in latency was observed. Among the other structures, the spinal cord seemed to be the most sensitive target to the epileptogenic action of penicillin-G, whereas in the remaining structures, sensitivity significantly decreased in rostro-caudal direction. As far as the features of the paroxysmal activity are concerned, significant differences among tested structures were observed. In particular, within the SI cortex, the main differences were represented by the gradual increase in burst frequency and voltage from the surface to the IVth layer and by their subsequent decrease in deeper layers (V-VI). In the diencephalon, the paroxysmal activity was similar to that observed in more superficial and deeper cortical layers even though epileptic bursts showed a lower amplitude. Mesencephalon and rombencephalon displayed a paroxysmal activity with a distinctive feature, characterized by long lasting bursts of low amplitude, although bulbar outbursts showed a shorter duration than the mesencephalic ones. In the spinal cord, the epileptiform activity displayed a different paroxysmal pattern, characterized by the longest duration and the highest amplitude. The different sensitivities of the investigated brain structures to penicillin-G and the characteristics of the induced paroxysmal activity have been extensively discussed.

Field test for mechanical efficiency evaluation in matching volleyball players

Field tests were performed in 10 volleyball (VB) players (4 females and 6 males) in order to obtain an index of mechanical work efficiency (mu' = Wmec/Woxy) while athletes played a game. Wmec was the mechanical work output, obtained by means of home made video image analysis software, by summing potential, kinetic translational and kinetic rotational energies of running and jumping athletes. Woxy was the oxidative energy consumption obtained from O2 consumption (VO2) by a telemetry device (Cosmed K2) that also gave values of pulmonary ventilation (VE) and heart rate (HR). VB were studied at rest before a game (R), during attacking phases (A) and during defensive phases (D). At R were found: VE = 11 +/- 1 l x min(-1), HR = 78 +/- 7b x min(-1), VO2 = 3.71 +/- 1.1 ml x kg(-1) x min(-1), Woxy = 75.1 +/- 22.3 J x kg(-1) x min(-1). During A all variables increased: VE = 49 +/- 6l x min(-1), HR = 149 +/- 15 b x min(-1), VO2 = 23.1 +/- 3.3ml x kg(-1) x min(-1), Woxy = 482.8 +/- 69.0 J x kg(-1) x min(-1), and Wmec 275.5 +/- 57.0 J x kg(-1) x min(-1) with mu'=0.57 +/- 0.09. In D HR (-9%), VE, VO2 and Woxy (-18%) were reduced when compared to A, decreasing mu' to 0.21 +/- 0.05. On the other hand mu' was found higher than 0.25 during A indicating an anaerobic contribution to energy expenditure; in D the mu' lower than 0.25 indicated a restoration of anaerobic energy sources. It might be proposed that a greater difference in mu' values between A and D also means a higher anaerobic energy contribution to the volleyball game.

The decrease of serotonin release induced by a tryptophan-free amino acid diet does not affect spatial and passive avoidance learning

We assessed whether consumption of a diet lacking in tryptophan (TRP) resulted in alteration in learning and memory performance and hippocampal 5-HT release in rats. Two hours after the acute administration of TRP-free (T) and balanced (B) diet rats were trained in a one-trial passive avoidance task. The two groups of rats showed no significant difference in retention latencies. Two other groups of rats, fed with the above diets during the acquisition of a radial-arm maze task, showed no difference in baseline performance. The acute ingestion of the T diet produced a significant and long lasting decrease of hippocampal and cortical 5-HT release in rats when compared to the B diet, while the 12th day of the T diet, 5-HT was not detectable in the dialysate. These data indicate that the diminished brain release of 5-HT induced by a T diet is not sufficient to impair cognitive processes.

Acute administration of a tryptophan-free amino acid mixture decreases 5-HT release in rat hippocampus in vivo

The effect of oral administration of a tryptophan-free amino acid mixture or the same mixture containing tryptophan (Trp) on hippocampal serotonin (5-HT) extracellular levels was studied using in vivo brain microdialysis of freely moving rats. During chloral hydrate anesthesia rats were implanted with dialysis probes in the dorsal hippocampus, and experiments were performed 24 h later. In vehicle-treated rats, the extracellular levels of 5-hydroxyindolacetic acid (5-HIAA) and 5-HT did not change during 240 min after ingestion. Oral administration of the Trp-free amino acid mixture significantly decreased basal 5-HT and 5-HIAA output 100 min after ingestion (65 and 81% of basal value, respectively) and remained at this level for another 140 min. The amino acid mixture containing Trp failed to significantly change basal extracellular levels of 5-HT, but enhanced that of 5-HIAA by approximately 134%. Moreover, in rats receiving the Trp-free amino acid mixture, the increase of hippocampal 5-HT release induced by d-fenfluramine (206%) was smaller than that released by the same drug in rats receiving the nutritionally balanced amino acid mixture (271%). Thus these results show that removal of Trp from the balanced amino acid mixture decreases spontaneous and d-fenfluramine-induced release of 5-HT in the hippocampus. In conclusion, our study supports the hypothesis that the mood-lowering effect observed in man after ingestion of a Trp-free amino acid mixture is associated with diminished 5-HT release in the brain.

Does long-term potentiation occur in guinea-pig Deiters' nucleus?

Long-term potentiation (LTP) was studied in the lateral vestibular nucleus (LVN-Deiters' nucleus) in guinea-pigs in vivo. Field potentials and extracellular single unit discharges were recorded in the LVN following electrical stimulation of the ipsilateral VIIIth nerve. High-frequency stimulation (HFS) of the VIIIth nerve fibres produced LTP of the monosynaptic component of the vestibular field potential. The LTP of the field potentials was paralleled by an increase of the evoked spike activity. Intranuclear administration of the NMDA antagonist MK-801 prevented LTP of the monosynaptic component of the vestibular field potentials and significantly suppressed the spontaneous firing of lateral vestibular neurones in a dose-dependent fashion. These results demonstrate that synapses between primary afferent fibres and second order LVN neurones undergo long lasting changes following HFS of the ipsilateral vestibular nerve.

Chronic ethanol consumption in rats: correlation between memory performance and hippocampal acetylcholine release in vivo

The effects of chronic alcohol consumption on memory performance and hippocampal acetylcholine release in vivo were investigated in rats. Rats were allowed to drink 25% (v/v) ethanol solution as the only source of fluid for nine consecutive months, whereas control rats received only tap water. Memory performance was tested by the acquisition of shuttle box active and passive avoidance. Chronic ethanol-consuming rats were not impaired in the acquisition of the active avoidance response task, whereas in the passive avoidance task, latency scores of treated rats were significantly lower than in controls. The basal release of acetylcholine in freely moving rats, assessed by the microdialysis technique, was significantly decreased in ethanol-treated rats. Impairment in memory performance, as assessed in the passive avoidance task, was significantly correlated with hippocampal acetylcholine release in vivo.

Increased hippocampal acetylcholine release during a working memory task

In this study we examined whether the food-reinforced alternation performance was associated with increased acetylcholine output in the dorsal hippocampus. Rats were trained to acquire the task using a T-maze. The control group consisted of rats introduced into the T-maze to run only on the day of dialysis. Acetylcholine release increased significantly in control rats only in the first 10 min after they were put into the T-maze. In trained rats acetylcholine output increased in the waiting cage as well as during trials in the T-maze. The increase in acetylcholine output in rats that had learned the task was significantly greater than in control rats.

Long-lasting changes of neuronal activity in the motor cortex of cats

The effect of tetanic intracortical microstimulation (ICMS) of superficial layers of the motor cortex on unit discharges responding to stimulation of the peripheral receptive fields was examined in the motor cortex (area 4y). Single or multiple unit discharges were isolated from 15 recording sites near the stimulating electrodes. Following tetanic ICMS, the response to the same peripheral stimulation showed a long lasting increase at six recording sites, a long lasting decrease at two sites and transient increase or decrease at four sites. In the rest of the sites, tetanic ICMS had no effect. The results demonstrate the existence of use-dependent modification of information processing in the motor cortex and support the hypothesis that the motor cortex participates in learning motor skills.

Trigeminal motoneuron responses to vestibular stimulation in the guinea pig

Experiments performed in the guinea pig were aimed at evaluating the effect of electric or caloric stimulations of the vestibular afferents on the electrical activity of the jaw-closing and jaw-opening trigeminal motoneurons. Results showed that masseter and digastric motoneurons mainly responded to vestibular ampullar activation with excitatory responses, with latencies being shorter for contralateral than ipsilateral ampullar stimulation. Differences in latencies between the jaw-closing and jaw-opening trigeminal motoneurons were observed: the masseter motoneurons constantly responded about 2 msec earlier than the digastric motoneurons. These results suggest that the vestibular-trigeminal relationship is quite complex and uses multiple systems to connect the vestibular apparatus with the trigeminal motor nuclei. From the functional point of view, the vestibular-trigeminal relationship may play a role in the dynamic control of the jaw muscle tone during head movements.

Olfactory influence on tongue activity

Recent findings have shown that olfactory stimulation by brief puffs of air odorized with amyl acetate induces several patterns of response in rabbit hypoglossal neurons. It has been argued that the functional role of the olfactory input may be the modulation of tongue muscular tone during the oral phase of digestion. In the present research, the peripheral effect of olfactory-hypoglossal modulation was analyzed. Both the spike traffic along the fibers of the hypoglossal nerve and the electromyographic activity of single tongue muscles (genioglossus, styloglossus, superior longitudinal and hyoglossus) were recorded before, during and after olfactory stimulation. Results showed that brief puffs of air odorized with amyl acetate induced a significant change in the efferent volleys along the hypoglossal nerve, as well as a substantial modulation of tongue muscle activity. Olfactory stimulation induced a significant increase in the spontaneous activity of both type I and type II genioglossal fibers; excitation followed by inhibition both in tonic and phasic styloglossal fibers; excitatory responses in tonic and phasic superior longitudinal fibers and short-lasting excitatory responses in the hyoglossal fibers. The diverse patterns of activation of the tested muscle and the significant differences between fibers, tonically or phasically controlled by the XIIth neurons, indicate that olfaction may be strongly involved in tongue reflex regulation. Different functional hypothesis are discussed about the role played by olfaction in the economy of tongue muscle activity.

Effects of the calcium channel antagonist darodipine on ethanol withdrawal in rats

The effect of the dihydropyridine calcium channel antagonist, darodipine, on ethanol withdrawal syndrome was examined in rats made dependent on ethanol by repeated ethanol administration for six consecutive days. Chronic co-administration of darodipine prevented the severity of ethanol withdrawal signs in a dose-dependent fashion. By contrast, acute administration of darodipine during the ethanol withdrawal phase was ineffective in reversing the withdrawal symptoms. The results suggest that the presence of darodipine in the central nervous system during the adaptative responses to ethanol is necessary to reduce the severity of the withdrawal syndrome. They also provide further evidence for a potential clinical usefulness of dihydropyridine calcium channel blockers in treatment of ethanol withdrawal.

Long-term potentiation within the cat motor cortex

Synaptic plasticity in the motor cortex of anesthetized cats was examined using intracellular recording and labeling techniques. Intracortical microstimulation (ICMS) was delivered in the superficial layers and recordings were made from cells in layer V. When the neuron responded to ICMS with an excitatory postsynaptic potential (EPSP), tetanic ICMS (100-200 Hz, 10-20 s) was delivered to the same site. Five of 19 cells which were examined and labeled with biocytin showed long-term potentiation (LTP) of the EPSP, and 12 cells showed post-tetanic potentiation (PTP) following the tetanic stimulation. All the examined cells were pyramidal neurons. These results demonstrate that plasticity exists within the intracortical connection of the motor cortex that may be involved in motor learning.

Cerebellar and mesencephalic influence on bulbar penicillin-G epileptogenesis in rats

The influence of the cerebellum and mesencephalon on epileptic bulbar discharge induced by topical application of penicillin-G on the floor of the IVth ventricle was analyzed in rats. Bulbar multiunit activity was recorded at different depths. The animals were divided into two main groups: totally cerebellectomized rats (Group I) and lobus anterior cerebellectomized rats (Group II). Each main group was further subdivided into two subgroups: animals with intact mesencephalon and animals with transected mesencephalon. In Group I: the total cerebellectomy, in intact mesencephalic rats (first subgroup) induced a sudden disappearance of bulbar epileptic discharge. The mid-collicular transection (second subgroup) produced the immediate disappearance of bulbar paroxysms and the total cerebellectomy, subsequently performed, further decreased the spontaneous firing rate. In Group II: (first subgroup) the lobus anterior ablation in rats with intact mesencephalon, significantly enhanced the paroxysmal discharge. In the second subgroup, where the midcollicular transection had provoked the disappearance of bulbar paroxysms, the lobus anterior ablation induced the immediate reappearance of the paroxysmal activity. The penicillin-G epileptogenic activity showed a different intensity at different depths in the bulb with a maximum intensity at the level of the vestibular nuclei. In conclusion, the present study shows that both the mesencephalon and the cerebellum have a facilitating influence on bulbar epileptic discharge induced by the topical application of the GABA antagonist. However, not all the cerebellum has a facilitating effect, because the anterior lobus was found to have an inhibitory influence on bulbar discharge.(ABSTRACT TRUNCATED AT 250 WORDS)

Visual and vestibular projections to tongue motoneurons

The rabbit hypoglossal neurons, localized in the mediocaudal part of the XIIth nucleus, receive visual and vestibular inputs able to induce reflex responses functionally driven both to prepare the oral cavity for food reception and to ensure a correct postural arrangement of the tongue. The aim of the present research was to show a possible convergence of visual input on the hypoglossal neurons modulated by the vestibular system and, thus, demonstrate that visual input plays a part in the control of the tongue posture. It was found that 78% of tested neurons responded to both photic stimulation of the retinae, performed by a conventional strobe unit, and electrical stimulation of the labyrinth, with different patterns of response. Moreover, visual input significantly modified both the hypoglossal neuron response and the electromyographic genioglossal response to caloric stimulation of the labyrinth. Because a significant visual influence on the hypoglossal nucleus response and the genioglossal muscle response to labyrinthine stimulation was observed, it can be concluded that vision does integrate the spatial information of the labyrinth to modulate the postural tone of the tongue muscles.

The brainstem cardioarrhythmogenic triggers and their possible role in sudden epileptic death

The cardiovascular effects of simultaneous activation of hypothalamic and mesencephalic cardioarrhythmogenic triggers were studied in hemispherectomized rats. Paroxysmal activity of hypothalamic neurons (HEF), elicited by topical application of penicillin G on the thalamus, triggered short-lasting bradyarrhythmic episodes, up to a maximum of 6 s, and alterations in repolarization. In the hypothalamic neurons, an additional penicillin G epileptic focus at mesencephalic level (MEF) induced the enhancement of paroxysmal activity by a recruitment of new units and potentiation of their background activity. HEF+MEF triggered second-degree 2:1-8:1 atrioventricular (A-V) blocks, impairment of the A-V conduction, alterations in the recovery phase and bundle branch blocks. After HEF, the arterial blood pressure decreased by 4-6%. HEF+MEF induced a further reduction of 17% in systolic pressure only. It is possible that the enhancement of the HEF following MEF could depend on MEF spreading upward. The HEF, in turn, by spreading downward could influence the MEF and so activate, between HEF and MEF, a circuitry with reciprocal co-excitation that could explain the more serious cardiovascular alterations observed during HEF+MEF compared with those observed during HEF only or during MEF only. However, this cardiovascular impairment, which must be neurogenic in origin as it was observed in animals with normal acid-base and blood parameter values, did not induce heart death. Thus, additional concomitances must be considered, such as metabolic derangement which can occur during seizures, to explain sudden death in epileptic patients. Some aspects of metabolic complications in cardiac activity during epilepsy are also discussed.

Olfactory modulation of hypoglossal neuron activity

Amyl acetate stimulation of the neuroepithelial cells of the olfactory mucosa induced significant responses in the olfactory bulb and modulated the spontaneous electrical activity of the hypoglossal neurons localized in the mediocaudal part of the XIIth nucleus. Olfactory stimulation induced several patterns of responses characterized by excitation, inhibition and combined effects frequently dependent upon the stimulation intensity. In addition, olfactory inputs converge with the visual inputs on the same part of the XIIth nucleus. The olfactory inputs inducing hypoglossal excitatory responses increased the hypoglossal excitation produced by visual stimuli and decreased its inhibition. Viceversa, the olfactory inputs inducing hypoglossal inhibitory responses decreased excitation and increased hypoglossal inhibition to photic stimulation of the retinae. The possible pathways involved in carrying the olfactory inputs towards the hypoglossal nucleus, and the olfactory or non-olfactory origin of the hypoglossal responses were considered. With regard to the role played by this input in the economy of the hypoglossal function, it was concluded that olfactory inputs, alone or together with visual inputs, may induce tongue reflex adjustments associated with the oral phase of digestion to prepare the oral cavity for food reception.