A modified step-ramp-step protocol to prescribe constant-speed exercise in treadmill running.

PURPOSE: This study investigated whether a running-adapted version of the cycling-based "step-ramp-step" (SRS) protocol would improve prediction of V ˙ O2 in treadmill exercise compared to the traditional prescriptive approach. METHODS: Fourteen healthy individuals (6 females; 25 ± 6 years; 66.1 ± 12.7 kg) performed a treadmill-based SRS protocol including a ramp-incremental test to task failure followed by two constant-speed bouts within the moderate-(MODstep-below estimated lactate threshold; θLT), and heavy-intensity domains (HVYstep-between θLT and respiratory compensation point; RCP). Using the uncorrected V ˙ O2-to-speed relationship from the ramp exercise, three constant-speed bouts were performed at 40-50% between: baseline and θLT (CSEMOD); θLT and RCP (CSEHVY); and RCP and peak (CSESEV). For CSEMOD, CSEHVY, and CSESEV measured end-exercise V ˙ O2 was compared to predicted V ˙ O2 based on the: (i) "SRS-corrected" V ˙ O2-to-speed relationship (where MODstep and HVYstep were used to adjust the V ˙ O2 relative to speed); and (ii) linear "uncorrected" data. RESULTS: Average treadmill speeds for CSEMOD and CSEHVY were 7.8 ± 0.8 and 11.0 ± 1.4 km·h-1, respectively, eliciting end-exercise V ˙ O2 of 1979 ± 390 and 2574 ± 540 mL·min-1. End-exercise V ˙ O2 values were not different compared to SRS-predicted V ˙ O2 at CSEMOD (mean difference: 5 ± 166 mL·min-1; p = 0.912) and CSEHVY (20 ± 128 mL·min-1; p = 0.568). The linear "uncorrected" estimates were not different for CSEMOD (- 91 ± 172 mL·min-1; p = 0.068) but lower for CSEHVY (- 195 ± 146 mL·min-1; p < 0.001). For CSESEV (running speed: 13.8 ± 1.7 km·h-1), the end-exercise V ˙ O2 was not different from peak V ˙ O2 achieved during the ramp (3027 ± 682 vs. 2979 ± 655 mL·min-1; p = 0.231). CONCLUSION: In healthy individuals, the SRS protocol more accurately predicts speeds for a target V ˙ O2 compared to traditional approaches.

Nature-based interventions for physical health conditions: A systematic review and meta-analysis.

Nature-based interventions (NBIs) are activities, strategies, or programs taking place in natural settings, such as exercising in greenspaces, to improve the health and well-being of people by integrating the benefits of nature exposure with healthy behaviours. Current reviews on NBIs do not report the effects on different groups of physical health conditions. The purpose of this systematic review and meta-analysis was to identify and synthesize the evidence of the effect of NBIs on physical health outcomes and biomarkers of physical health conditions. Overall, 20,201 studies were identified through searching MEDLINE, Embase, CINAHL, SPORTDiscus, and CENTRAL databases up to June 7, 2024. Inclusion criteria were: 1) randomized controlled intervention studies; 2) population with a physical health condition; 3) NBIs vs. different intervention or no intervention; and 4) measuring physical health outcomes and/or biomarkers. Twenty-six studies were included in the review, 15 of which contributed to the meta-analysis. Compared to control groups, NBIs groups showed significant improvements in: diastolic blood pressure (MD -3.73 mmHg [-7.46 to -0.00], I2 = 62%) and heart rate (MD -7.44 bpm [-14.81 to -0.06], I2 = 0%) for cardiovascular conditions, fatigue (SMD -0.50 [-0.82 to -0.18], I2 = 16%) for central nervous system conditions, and body fat percentage (MD -3.61% [-5.05 to -2.17], I2 = 0%) for endocrine conditions. High effect heterogeneity was found in several analyses and the included studies had moderate-to-high risk of bias (RoB). The non-significant outcomes showed a direction of effect in favour of NBI groups for cardiovascular, central nervous system, endocrine, musculoskeletal, and respiratory conditions. This review found some beneficial effects in favour of NBIs for health outcomes in at least three condition groups though RoB and inconsistent effects limited some interpretations. NBIs are promising therapies that healthcare professionals can consider integrating into clinical practice.

The ventilatory response to modified rebreathing is unchanged by hyperoxic severity: implications for the hyperoxic hyperventilation paradox.

Normobaric hyperoxia stimulates ventilation (V̇e) in a time- and dose-dependent manner. Whether this occurs via an oxygen (O2)-specific mechanism or secondary to carbon dioxide (CO2) retention at the central chemoreceptors remains unclear. We measured the ventilatory response to hyperoxic CO2 rebreathing with O2 clamped at increasingly higher pressures. We hypothesized that the V̇e versus Pco2 relationship is fixed and independent of Po2. On four occasions, 20 participants (10 F; mean ± SD age: 24 ± 4 yr) performed three repetitions of modified rebreathing in four, randomized, isoxic-hyperoxic conditions: mild: Po2 = 150 mmHg; moderate: Po2 = 200 mmHg; high: Po2 = 300 mmHg; and extreme: Po2 ≈ 700 mmHg. Breath-by-breath V̇e, end-tidal CO2 ([Formula: see text]), and O2 ([Formula: see text]) were measured by pneumotach and gas analyzer. For each rebreathing trial, the [Formula: see text] at which V̇e rose was identified as the ventilatory recruitment threshold (VRT, mmHg), data before VRT provided baseline V̇e (V̇eBSL, L·min-1) and the slope of the response above VRT gave central chemoreflex sensitivity (V̇eS, L·min-1·mmHg-1). For each condition, VRT, V̇eBSL, and V̇eS from like-trials were averaged, and repeated measures ANOVA assessed between-condition differences. There were no effects of [Formula: see text] on V̇eBSL (mild: 7.4 ± 4.2 L·min-1; moderate: 6.9 ± 4.2 L·min-1; high: 6.5 ± 3.7 L·min-1; extreme: 7.5 ± 2.7 L·min-1; P = 0.24), VRT (mild: 42.8 ± 3.2 mmHg; moderate: 42.5 ± 2.7 mmHg; high: 42.3 ± 2.7 mmHg; extreme: 41.8 ± 2.7 mmHg; P = 0.07), or V̇eS (mild: 4.88 ± 2.6 L·min-1·mmHg-1; moderate: 4.76 ± 2.2 L·min-1·mmHg-1; high: 4.81 ± 2.3 L·min-1·mmHg-1; extreme: 4.39 ± 1.9 L·min-1·mmHg-1; P = 0.41). The V̇e-Pco2 relationship is unaltered across a range of mild to extreme Po2. Brief exposure to normobaric hyperoxia may not independently stimulate breathing nor does it alter central chemoreflex sensitivity.NEW & NOTEWORTHY Normobaric hyperoxia stimulates ventilation (V̇e) in a time- and dose-dependent manner. Whether this occurs directly or indirectly through heightened central carbon dioxide pressure (Pco2) or via central chemoreflex sensitization is unclear. Participants who performed modified rebreathing at high oxygen pressures (Po2) of 150, 200, 300, and ≈700 mmHg exhibited no changes to their ventilatory responses to Pco2. Brief exposure to normobaric hyperoxia may not independently stimulate breathing nor does it alter central chemoreflex sensitivity.

A test of the interaction between central and peripheral respiratory chemoreflexes in humans.

How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic CO2 tensions ( P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and central P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Twenty participants (10F) completed three repetitions of modified rebreathing tests with end-tidal P O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ ( P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) clamped at 150, 70, 60 and 45 mmHg. End-tidal P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ( P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ), P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , ventilation ( V ̇ $\dot{V}$ E ) and calculated oxygen saturation (SC O2 ) were measured breath-by-breath by gas-analyser and pneumotach. The V ̇ $\dot{V}$ E - P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship of repeat-trials were linear-interpolated, combined, averaged into 1 mmHg bins, and fitted with a double-linear function ( V ̇ $\dot{V}$ E S, L min-1 mmHg-1 ). PChS was computed at intervals of 1 mmHg of P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ as follows: the difference in V ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆ V ̇ $\dot{V}$ E ) was calculated; three ∆ V ̇ $\dot{V}$ E values were plotted against corresponding SC O2 ; and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). These processing steps were repeated at each P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ to produce the PChS vs. isocapnic P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship. These were fitted with linear and polynomial functions, and Akaike information criterion identified the best-fit model. One-way repeated measures analysis of variance assessed between-condition differences. V ̇ $\dot{V}$ E S increased (P < 0.0001) with isoxic P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ from 3.7 ± 1.5 L min-1 mmHg-1 at 150 mmHg to 4.4 ± 1.8, 5.0 ± 1.6 and 6.0 ± 2.2 Lmin-1 mmHg-1 at 70, 60 and 45 mmHg, respectively. Mean SC O2 fell progressively (99.3 ± 0%, 93.7 ± 0.1%, 90.4 ± 0.1% and 80.5 ± 0.1%; P < 0.0001). In all individuals, PChS increased with P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear model in 75%. Despite increasing central chemoreflex activation, PChS increased linearly with P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ indicative of an additive central-peripheral chemoreflex response. KEY POINTS: How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions ( P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and central P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Participants performed three repetitions of modified rebreathing with end-tidal P O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ fixed at 150, 70, 60 and 45 mmHg. PChS was computed at intervals of 1 mmHg of end-tidal P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ( P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) as follows: the difference in V ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆ V ̇ $\dot{V}$ E ) was calculated; three ∆ V ̇ $\dot{V}$ E values were plotted against corresponding calculated oxygen saturation (SC O2 ); and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). In all individuals, PChS increased with P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear (rather than polynomial) model in 15 of 20. Most participants did not exhibit a hypo- or hyper-additive effect of central chemoreceptors on the peripheral chemoreflex indicating that the interaction was additive.

Coupling of [Formula: see text] and [Formula: see text] kinetics: insights from multiple exercise transitions below the estimated lactate threshold.

During a step-change in exercise power output (PO), ventilation ([Formula: see text]) increases with a similar time course to the rate of carbon dioxide delivery to the lungs ([Formula: see text]). To test the strength of this coupling, we compared [Formula: see text] and [Formula: see text] kinetics from ten independent exercise transitions performed within the moderate-intensity domain. Thirteen males completed 3-5 repetitions of ∆40 W step transitions initiated from 20, 40, 60, 80, 100, and 120 W on a cycle ergometer. Preceding the ∆40 W step transitions from 60, 80, 100, and 120 W was a 6 min bout of 20 W cycling from which the transitions of variable ∆PO were examined. Gas exchange ([Formula: see text] and oxygen uptake, [Formula: see text]) and [Formula: see text] were measured by mass spectrometry and volume turbine. The kinetics of the responses were characterized by the time constant (τ) and amplitude (Δ[Formula: see text]/Δ[Formula: see text]). Overall, [Formula: see text] kinetics were consistently slower than [Formula: see text] kinetics (by ~ 45%) and τ[Formula: see text] rose progressively with increasing baseline PO and with heightened ∆PO from a common baseline. Compared to τ[Formula: see text], τ[Formula: see text] was on average slightly greater (by ~ 4 s). Repeated-measures analysis of variance revealed that there was no interaction between τ[Formula: see text] and τ[Formula: see text] in either the variable baseline (p = 0.49) and constant baseline (p = 0.56) conditions indicating that each changed in unison. Additionally, for Δ[Formula: see text]/Δ[Formula: see text], there was no effect of either variable baseline PO (p = 0.05) or increasing ΔPO (p = 0.16). These data provide further evidence that, within the moderate-intensity domain, both the temporal- and amplitude-based characteristics of V̇E kinetics are inextricably linked to those of [Formula: see text].

Strategies to improve respiratory chemoreflex characterization by Duffin's rebreathing.

NEW FINDINGS: What is the central question of this study? We assessed the test-retest variability of respiratory chemoreflex characterization by Duffin's modified rebreathing method and explored whether signal averaging of repeated trials improves confidence in parameter estimation. What is the main finding and its importance? Modified rebreathing is a reproducible method to characterize responses of central and peripheral respiratory chemoreflexes. Signal averaging of multiple repeated tests minimizes within- and between-test variability, improves the confidence of chemoreflex characterization and reduces the minimal change in parameters required to establish an effect. Future experiments that apply this method might benefit from signal averaging to improve its discriminatory effect. ABSTRACT: We assessed the test-retest variability of central and peripheral respiratory chemoreflex characterization by Duffin's modified rebreathing method and explored whether signal averaging of repeated trials improves confidence in parameter estimation. Over four laboratory visits, 13 participants (mean ± SD age, 25 ± 5 years) performed six repetitions of modified rebreathing in isoxic-hypoxic conditions [end-tidal P O 2 ${P_{{{\rm{O}}_{\rm{2}}}}}$ ( P ET , O 2 ${P_{{\rm{ET,}}{{\rm{O}}_{\rm{2}}}}}$ )  = 50 mmHg] and isoxic-hyperoxic conditions ( P ET , O 2 ${P_{{\rm{ET,}}{{\rm{O}}_{\rm{2}}}}}$   = 150 mmHg). End-tidal P C O 2 ${P_{{\rm{C}}{{\rm{O}}_{\rm{2}}}}}$ ( P ET , C O 2 ${P_{{\rm{ET,C}}{{\rm{O}}_{\rm{2}}}}}$ ), P ET , O 2 ${P_{{\rm{ET,}}{{\rm{O}}_{\rm{2}}}}}$ and minute ventilation ( V ̇ $\dot {\rm V}$ E ) were measured breath-by-breath, by gas analyser and pneumotachograph. The V ̇ $\dot {\rm V}$ E versus P ET , C O 2 ${P_{{\rm{ET,C}}{{\rm{O}}_{\rm{2}}}}}$ relationships were fitted with a piecewise model to estimate the ventilatory recruitment threshold (VRT) and the slope above the VRT ( V ̇ $\dot {\rm V}$ E S). Breath-by-breath data from the three within- and between-day trials were averaged using two approaches [simple average (fit then average) and ensemble average (average then fit)] and compared with a single-trial fit. Variability was assessed by intraclass correlation (ICC) and coefficient of variance (CV), and the minimal detectable change was computed for each approach using two independent sets of three trials. Within days, the VRT and V ̇ $\dot {\rm V}$ E S exhibited excellent test-retest variability in both hyperoxic conditions (VRT: ICC = 0.965, CV = 2.3%; V ̇ $\dot {\rm V}$ E S: ICC = 0.932, CV = 15.5%) and hypoxic conditions (VRT: ICC = 0.970, CV = 2.9%; V ̇ $\dot {\rm V}$ E S: ICC = 0.891, CV = 17.2%). Between-day reproducibility was also excellent (hyperoxia, VRT: ICC = 0.930, CV = 2.2%; V ̇ $\dot {\rm V}$ E S: ICC = 0.918, CV = 14.2%; and hypoxia, VRT: ICC = 0.940, CV = 3.0%; V ̇ $\dot {\rm V}$ E S: ICC = 0.880, CV = 18.1%). Compared with a single-trial fit, there were no differences in VRT or V ̇ $\dot {\rm V}$ E S using the simple average or ensemble average approaches; however, ensemble averaging reduced the minimal detectable change for V ̇ $\dot {\rm V}$ E S from 2.95 to 1.39 L min-1  mmHg-1 (hyperoxia) and from 3.64 to 1.82 L min-1  mmHg-1 (hypoxia). Single trials of modified rebreathing are reproducible; however, signal averaging of repeated trials improves confidence in parameter estimation.

Cardiovascular and single-unit responses to L-glutamate injection into the posterior insular cortex in rat.

The insular cortex in rat is a longitudinal strip that runs along the rostral half of the rhinal fissure. The previous studies showed connections between the posterior insular cortex (PIC) and some major cardiovascular centers. Based on the stimulation site, electrical or chemical stimulation of the PIC induced an increase or a decrease in blood pressure (BP) and heart rate (HR). There is no report of simultaneous cardiovascular and single-unit recording microinjection of Glut in the PIC. In this study, L-glutamate was microinjected into the PIC of urethane anesthetized rats and arterial pressure, HR and single-unit responses were recorded simultaneously. Also the response of the neurons to baroreceptor activation was explored. Glut produced five types of long oscillatory, pressor, depressor, bradycardic and tachycardic cardiovascular responses, with no association between pressure and HR responses. We also observed five single-unit responses, consisting of short excitatory, long oscillatory, excitatory, inhibitory and mixed responses. There was an association between oscillation in BP and in single-unit response. There were some differences between the two sides especially for single-unit responses. In conclusion, there were five types of cardiovascular and five types of single-unit responses, to Glut microinjection into PIC, from which three types were correlated. The left side of the PIC is involved more in the cardiovascular functions. These data along with the fact that most recorded neurons responded to baroreceptor activation, might imply the presence of feedback systems in the PIC, producing irregularity in BP and HR.

Cardiovascular and single-unit responses to microinjection of angiotensin II into the bed nucleus of the stria terminalis in rat.

The bed nucleus of the stria terminalis (BST) is part of the limbic system located in the rostral forebrain. BST is involved in behavioral, neuroendocrine and autonomic functions, including cardiovascular regulation. The angiotensin II (Ang II) receptor, AT1, was found in the BST, however its effects on the cardiovascular system and on single-unit responses have not been studied yet. In the present study, Ang II was microinjected into the BST of anesthetized rats and cardiovascular and single-unit responses were recorded simultaneously. Furthermore the responses were re-tested after the microinjection of a blocker of the AT1 receptor, losartan, into the BST. We found that microinjection of Ang II into the BST produced a pressor response of 11±1mmHg for a duration of 2-8min. Ang II had no consistent effect on heart rate. It also produced two types of single-unit responses in the BST, short excitatory and long inhibitory. Blockade of AT1 receptors abolished both the cardiovascular and single-unit responses, indicating that the responses were mediated through AT1 receptors. These findings imply that Ang II may be utilized as a neurotransmitter and may play a role in returning blood pressure toward normal during hypotension.

Effect of chronic stress on short and long-term plasticity in dentate gyrus; study of recovery and adaptation.

Stress dramatically affects synaptic plasticity of the hippocampus, disrupts paired-pulse facilitation and impairs long-term potentiation (LTP). This study was performed to find the effects of chronic restraint stress and recovery period on excitability, paired-pulse response, LTP and to find probable adaptation to very long stress in the dentate gyrus. Thirty-eight male Wistar rats were randomly divided into four groups of Control, Rest-Stress (21 days stress), Stress-Rest (recovery) and Stress-Stress (42 days stress: adaptation). Chronic restraint stress was applied 6-h/day. Input-output functions, paired-pulse responses and LTP were recorded from the dentate gyrus while stimulating the perforant pathway. We found that chronic stress attenuated the responsiveness, paired-pulse response and LTP in the dentate gyrus. A 21-day recovery period, after the stress, improved all the three responses toward normal, indicating reversibility of these stress-related hippocampal changes. There was no significant adaptation to very long stress, probably due to severity of stress.

Glutamate injection into the cuneiform nucleus in rat, produces correlated single unit activities in the Kolliker-Fuse nucleus and cardiovascular responses.

The cuneiform (CnF) and Kolliker-Fuse (KF) nuclei are implicated in several functions including regulation of cardiovascular system and pain modulation. The KF also is a potential candidate for relaying the CnF cardiovascular responses to the rostral ventrolateral medulla (RVLM). In a previous study we showed that blockade of the KF strongly attenuated the short responses and moderately attenuated the long responses to glutamate microinjection into the CnF, suggesting that the cardiovascular effects of the CnF, especially the short responses, were mediated by the KF. In the present study the cellular basis of the cardiovascular responses of the CnF and possible role of the KF in relaying them to the RVLM were explored. In one group, l-glutamate was microinjected in the CnF and the cardiovascular responses were recorded. In another group the single unit responses of the KF to l-glutamate injection into the CnF were recorded. Our results showed that chemical stimulation of the CnF with glutamate produced mainly excitatory cardiovascular and single unit responses and a minority of mixed (excitatory and inhibitory) responses. In about one fourth of the cases there were no responses to stimulation. Various patterns of each group were presented and compared between cardiovascular and single unit responses. Similarities were found between cardiovascular and single unit response patterns, suggesting a significant role of KF neurons in mediating the CnF cardiovascular responses to the RVLM.

Ascorbate reduces morphine-induced extracellular DOPAC level in the nucleus accumbens: A microdialysis study in rats.

Most drugs of abuse increase dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) release in the shell of the nucleus accumbens. The effects of ascorbate, which is known to modulate dopamine neurotransmission, on the extracellular level of DOPAC in the nucleus accumbens of naive rats and of rats treated acutely with morphine were studied by using in vivo microdialysis and high performance liquid chromatography with electrochemical detection (HPLC-ECD). Acute morphine (20 mg/kg ip) treatment increased the level of DOPAC in the nucleus accumbens to approximately 170% of basal level. Acute treatment with ascorbate (500 mg/kg ip) alone did not alter nucleus accumbens' DOPAC level, but pretreatment with ascorbate (500 mg/kg ip) 30 min before morphine administration attenuated the effects of acute morphine on the level of DOPAC. These results suggest that ascorbate modulates the mesolimbic dopaminergic pathway.

Ascorbic acid decreases morphine self-administration and withdrawal symptoms in rats.

Recent studies have indicated that the glutamatergic system is involved in the motivational aspects during the initiation of drug self-administration. Ascorbic acid (AA), an antioxidant vitamin, is released from glutamatergic neurons, and it modulates the synaptic action of dopamine and glutamate. In this study the AA effects on the self-administration of morphine and on the morphine withdrawal syndrome have been investigated. Wistar rats were allowed to self-administer morphine (1 mg/infusion) during 10 consecutive days for 2 h/session. The number of lever pressings was recorded. An intrapritoneal AA injection (500 mg/kg, i.p.), 30 min before morphine self-administration produced a significant decrease in the initiation of morphine self administration during all sessions. After the last test session morphine withdrawal symptom signs (MWS) were recorded after naloxone precipitation. Most of MWS (but not all) were decreased by AA application. In conclusion, AA may change the motivational processes underlying the morphine self-administration.

[Use of the intraosseous route in a premature infant]. / Utilisation de la voie intraosseuse chez un prématuré.

BACKGROUND: The intraosseous route (IOR) is a rehabilitated vascular access in emergency situations. Its indications and duration are defined, although the age limit at which it is usable is not clearly established. CASE REPORT: A 34-week-old preterm neonate, without infection, receiving gastric gavage, developed, at 8 days of life, a severe septic shock requiring ventilatory support and emergency volume expansion via a subclavian catheter. During the chest X-ray to check its position, the catheter was unfortunately pulled out. The child presented an acute desaturation with bradycardia, requiring bag ventilation and endotracheal epinephrine. The umbilical vein being unusable, an intraosseous access (20 G, distal hole, Cook) was performed at the upper tibial level to continue resuscitation and left in place for 14 hours to infuse antibiotics, inotropic support, blood products and colloids. Blood cultures grew Klebsiella pneumoniae. After a severe initial phase, course was favorable with normal examination at 3 years without complication of the IOR. DISCUSSION: To our knowledge, it is the youngest child in whom IOR was performed. For neonates and especially preterms, the site of puncture is just below the tibial superior tuberosity, otherwise there is a risk of fracture of the diaphysis. This risk justifies the control of the IOR by X-ray. The place of the IOR among emergency vascular accesses in neonates, seems to us to be reserved to situations when umbilical vein is unusable. CONCLUSION: Although no study compared IOR to superior longitudinal sinus access, we suggest to reserve the sinus access only when IOR has failed, because of its potential cerebral complications.

[Neurologic manifestations in a child of a mother with gestational herpes]. / Manifestations neurologiques chez un enfant de mère atteinte d'herpès gestationis.

BACKGROUND: Herpes gestationis in the neonate is usually associated with an increased risk of premature birth and/or low birth weight for gestational age (GA) and sometimes skin lesions. Neurologic manifestations are nos described in these babies. CASE REPORT: A boy was born at 35 weeks of GA from a mother who developed skin eruption typical of herpes gestationis. His weight was 2320 g and his height was 46 cm. He had transient respiratory distress syndrome and was given antibiotics due to suspected group B streptococcus infection. He developed on day 3 skin vesiculous eruption which disappeared within 3 days and neurologic manifestations: hypertonia and hyperkinesis, abnormal EEG. The CSF was normal. The manifestations spontaneously disappeared within 5 days. The herpes gestationis factor was present in both mother and infant. CONCLUSION: A relationship between the maternal herpes gestationis and neonatal neurologic manifestations is possible; there was no other known causes for the transient neurological disease.

[What is the choice of training in neonatal intensive care? Analysis of wishes from 106 neonatologists]. / Quels choix pédagogiques pour la formation à la réanimation du nouveau-né? Analyse des souhaits de 106 néonatologues.

BACKGROUND: Improvement of the care to the neonate relys on an increased number of pediatricians in nurseries and adequate neonatal resuscitation training. METHODS: A questionaire about the optimal modes of neonatal resuscitation training was sent to 132 pediatricians in charge of a neonatal unit or a neonatal intensive care unit. Response rate was 80.3%. RESULTS: The training program was targeted to be regional for the organization and for the evaluation. Nevertheless, 41% of answers also favored local evaluation. Duties in neonatal intensive care unit or transportation system, with differences among areas, were the proposed training choices. The pediatrician was considered to be the first person as an instructor and also as a learner in a multidisciplinary training program. Cooperation between primary and tertiary centers physicians was proposed as the best way for training. Proposed criteria for evaluating training efficacy included neonatal mortality and meconium aspiration syndrome rates. Government funding was suggested in 92% of answers. CONCLUSION: It seems necessary to perform a wide neonatal resuscitation training program. This multidisciplinary approach should be regional and follow the guidelines of the neonatal study group.