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Biomedical subjects

M Amri

Publications and source records attributed to M Amri.

At least 19 recordsLinked to original sources
PubMed2006

Alterations in interferon-gamma and nitric oxide levels in human echinococcosis.

Human cystic hydatid disease is characterized by the long-term coexistence of Echinococcus granulosus and its host without effective rejection of the parasite. This parasitic helminth infection currently constitutes a major health problem in Algeria. We investigated interferon-gamma (IFN-gamma) and nitrite (NO2-) production in PBMC culture 2 supernatants from Algerian patients (n = 35), stimulated by a major antigen (antigen 5). Nitrite was also observed in 74 sera and 28 cyst fluids of patients carrying cysts in different locations. In addition, we report the detection of Nitric Oxide Synthase-2 (NOS2) in liver biopsies of patients (n = 8) by an immunochemical method using human NOS2 antibody. In vivo nitrite levels in host sera and cyst biological fluid point to a tight relation between host response and macro-parasite effects. Our in vitro results indicate a correlation between nitrite and IFN-gamma production in PBMC culture supernatants. Furthermore, by immunohistochemistry NOS2 expression was observed in hepatocytes and Küpffer cells from hydatid patients. Collectively, our data imply NO production in host defense against the extracellular parasite, probably in response to an IFN-gamma activating signal. Concomitant enhanced levels of IFN-gamma and nitrite represent useful indicators of the clinical aggressiveness of hydatidosis.

Adult↗
PubMed2005

Effect of combined active recovery from supramaximal exercise on blood lactate disappearance in trained and untrained man.

The purpose of this study was to determine the effect of different modalities of individualized active recovery on blood lactate disappearance after supramaximal exercise in subjects with different levels of aerobic fitness. Fourteen healthy subjects (7 trained and 7 untrained subjects mean age 20 +/- 1.5 and 19.5 +/- 1.5, respectively) participated in this study. They performed three supramaximal intermittent exercises at 60 % of the time to exhaustion at 120 % of the maximum aerobic power (MAP) with 5-min recovery periods (2 x 5 min). The third exercise was followed by 20 min of recovery. The effects of four types of recovery were compared in trained and untrained subjects: passive recovery (PR), an active recovery at an intensity corresponding to the first anaerobic ventilatory threshold minus 20 % (VT1), an active recovery at an intensity corresponding to the second anaerobic ventilatory threshold minus 20 % (VT2) and a combined active recovery (CR) which consisted of 7 min at VT2 followed by 13 min at VT1. Blood lactate levels were measured at rest and during the recovery periods. Peak blood lactate after supramaximal exercise was observed significantly earlier with VT2 and CR (4th min) than VT1 and PR (7th min) in trained and in untrained subjects. Combined active recovery (CR) showed a significantly faster lactate disappearance than did PR, VT1, or VT2 from the 7th min of recovery in trained subjects (p < 0.05) and at the 20th min in untrained subjects (p < 0.05). CR and VT2 conditions showed earlier peak blood lactate (4th min) than PR or VT1 (7th min). Blood lactate disappearance was faster in trained than untrained subjects during combined active recovery. This result suggests that the level of physical fitness plays an important role mainly in the pattern of blood lactate decrease during combined active recovery.

Adult↗
PubMed2005

Effects of intra-session concurrent endurance and strength training sequence on aerobic performance and capacity.

AIM: To examine the effects of the sequencing order of individualised intermittent endurance training combined with muscular strengthening on aerobic performance and capacity. METHODS: Forty eight male sport students (mean (SD) age 21.4 (1.3) years) were divided into five homogeneous groups according to their maximal aerobic speeds (vV*o2max). Four groups participated in various training programmes for 12 weeks (two sessions a week) as follows: E (n = 10), running endurance training; S (n = 9), strength circuit training; E+S (n = 10) and S+E (n = 10) combined the two programmes in a different order during the same training session. Group C (n = 9) served as a control. All the subjects were evaluated before (T0) and after (T1) the training period using four tests: (1) a 4 km time trial running test; (2) an incremental track test to estimate vV*o2max; (3) a time to exhaustion test (t(lim)) at 100% vV*o2max; (4) a maximal cycling laboratory test to assess V*o2max. RESULTS: Training produced significant improvements in performance and aerobic capacity in the 4 km time trial with interaction effect (p < 0.001). The improvements were significantly higher for the E+S group than for the E, S+E, and S groups: 8.6%, 5.7%, 4.7%, and 2.5% for the 4 km test (p < 0.05); 10.4%, 8.3%, 8.2%, and 1.6% for vV*o2max (p < 0.01); 13.7%, 10.1%, 11.0%, and 6.4% for V*o2max (ml/kg(0.75)/min) (p < 0.05) respectively. Similar significant results were observed for t(lim) and the second ventilatory threshold (%V*o2max). CONCLUSIONS: Circuit training immediately after individualised endurance training in the same session (E+S) produced greater improvement in the 4 km time trial and aerobic capacity than the opposite order or each of the training programmes performed separately.

Adaptation, Physiological↗
PubMed2005

Effects of dominant somatotype on aerobic capacity trainability.

PURPOSE: This study examined the association between dominant somatotype and the effect on aerobic capacity variables of individualised aerobic interval training. METHODS: Forty one white North African subjects (age 21.4+/-1.3 years; Vo2max = 52.8+/-5.7 ml kg(-1) min(-1)) performed three exercise tests 1 week apart (i) an incremental test on a cycle ergometer to determine Vo2max and Vo2 at the second ventilatory threshold (VT2); (ii) a VAM-EVAL track test to determine maximal aerobic speed (vVo2max); and (iii) an exhaustive constant velocity test to determine time limit performed at 100% vVo2max (tlim100). Subjects were divided into four somatometric groups: endomorphs-mesomorphs (Endo-meso; n = 9), mesomorphs (Meso; n = 11), mesomorphs-ectomorphs (Meso-ecto; n = 12), and ectomorphs (Ecto; n = 9). Subjects followed a 12 week training program (two sessions/week). Each endurance training session consisted of the maximal number of successive fractions for each subject. Each fraction consisted of one period of exercise at 100% of vVo2max and one of active recovery at 60% of vVo2max. The duration of each period was equal to half the individual tlim100 duration (153.6+/-39.7 s). After the training program, all subjects were re-evaluated for comparison with pre-test results. RESULTS: Pre- and post-training data were grouped by dominant somatotype. Two way ANOVA revealed significant somatotype-aerobic training interaction effects (p<0.001) for improvements in vVo2max, Vo2max expressed classically and according to allometric scaling, and Vo2 at VT2. There were significant differences among groups post-training: the Meso-ecto and the Meso groups showed the greatest improvements in aerobic capacity. CONCLUSION: The significant somatotype-aerobic training interaction suggests different trainability with intermittent and individualised aerobic training according to somatotype.

Adaptation, Physiological↗
PubMed2002

The role of myoglobin in retarding oxygen depletion in anoxic heart.

The present study explores the role of myoglobin (Mb) in retarding the development of anoxia in the perfused working rat heart. We examine this phenomenon by analyzing the behavior and the kinetics of Mb oxygenation and cytochrome aa3 (cytaa3) redoxation. Absorbance changes, measured at wavelength pairs specific to Mb and cytaa3, show parallelism between the Mb oxygenation status and the redox states of cytaa3. Induction of anoxia leads to early and accelerated Mb deoxygenation whereas cytaa3 reduction marks a slight delay and its rate is twice slower than that of Mb. Then, when Mb is desatured above 50%, the cytaa3 reduction becomes accelerated. With the reoxygenated perfusion following the anoxia, the rate of Mb reoxygenation is twice faster than that of the cytaa3 reoxidation. When the oxygen-binding function of Mb, in situ in the heart, is abolished by treatment with sodium nitrite (NaNO2), the redox kinetics of cytaa3 show significant perturbations. Induction of anoxia leads to a precocious and accelerated reduction of cytaa3, compared to the same anoxic heart before the treatment. At reoxygenation, the reoxidation rate of cytaa3 decreases significantly, compared to that before the treatment. Similarly, in the nitrite treated heart, the phosphocreatine (PCr) level decreases to 60% of the control, whereas the inorganic phosphate (Pi) level increases to 300%. ATP concentration, however, remains constant. We conclude from these results that Mb may support mitochondrial respiration at the critical levels of the myocardial O2 supply.

Animals↗
PubMed2001

[Sweet's syndrome].

Sweet's syndrome or acute febrile neutrophilic dermatosis is relatively frequent. It can be isolated or associated to other diseases, particularly, inflammatory or autoimmune diseases, lymphoproliferative or malignant disorders. In this retrospective study, we report 10 cases of Sweet's syndrome recorded over a 42 months period. The female predominance was net (9 womens for 1 man). The mean age was 45 years. The diagnosis was established, in all cases, on clinical, biological and histological criteria. The lesions occurred most commonly on legs (9 cases). The failure of antibiotics has been noted in all patients, and colchicine has been demonstrated efficient in 6 patients. Our study confirms the interest of cutaneous biopsy in case of papulo-nodular lesions which has not respond to antibiotics.

Adult↗
PubMed2000

Effects of lingual nerve afferents on swallowing in sheep.

We investigated in sheep the effects of stimulation of the thick afferent fibers running through the lingual nerve (LN) upon the activity of some of the muscles and medullary interneurons or motoneurons which are active during swallowing. Using electromyography (EMG), and extra- and intracellular neuronal recording, we demonstrated that LN stimulation inhibited triggering and/or distal progression of deglutition reflexly induced by stimulation of the superior laryngeal nerve (SLN). This inhibition appeared as a delay, or the interruption or total suppression, of the EMG and neuronal swallowing activities, depending on the interval between SLN and LN stimulation. It was apparent at the level of the muscles and motoneurons of the nucleus ambiguus, as well as at the level of the interneurons of the dorsal medulla within or around the nucleus of solitary tract, which are assumed to be the core of the organizing system for swallowing, the so-called central pattern generator (CPG). Taking into account the stimulation parameters used in our experiments, it was likely that only LN-mechanosensitive fibers were excited. These fibers were involved in the jaw-opening reflex, and possibly in mastication regulation. Therefore, inhibition of swallowing could result from interactions between the hindbrain mastication and swallowing CPGs. However, it was also possible that mechanosensitive afferents acted upon the swallowing CPG directly or indirectly through supramedullary, especially cortical, loops.

Afferent Pathways↗
PubMed1999

Stimulation of the chewing area of the cerebral cortex induces inhibitory effects upon swallowing in sheep.

Mastication and swallowing are two tightly integrated components of food intake behavior. We investigated the effects of stimulating the chewing area of the fronto-orbital cortex (CCx) on some muscles and medullary interneurons (Ins) or motoneurons (Mns) active during swallowing. For the purpose of comparison, the lingual nerve (LN) was also stimulated during the experiments. Electromyography (EMG) and extracellular neuronal recording were used, and swallowing was reflexly induced (RIS) by stimulation of the superior laryngeal nerve (SLN). RIS was almost totally abolished during long-lasting repetitive stimulation of CCx or LN, and was strongly facilitated after stimulation cessation. Short-duration stimulation (one or a few pulses) of both the CCx and LN also inhibited triggering of deglutition when delivered just before the onset of RIS. This inhibition appeared as a delay or total suppression of the EMG and neuronal swallowing activities. It was obvious at the level of the muscles, the hypoglossal Mns and the premotoneurons (PMns; Ins of the ventral medulla near the nucleus ambiguus), as well as at the level of the Ins of the dorsal medulla (within or around the solitary tract nucleus) which are assumed to be the core of the 'central pattern generator' (CPG) for swallowing. In addition to the 'chewing-related inhibition', many ventral Ins exhibited a short latency synaptic activation after CCx and/or LN stimulation. Therefore, these Ins may play a pivotal role for reflex or cortical fast control of tongue (and jaw) muscles, and for coordinating their contractions in the context of mastication-deglutition interactions.

Animals↗
PubMed1997

Intracellular activity of motoneurons of the rostral nucleus ambiguus during swallowing in sheep.

The nervous mechanisms that generate swallowing are still largely unknown. It has been suggested that a central pattern generator that contains a serial network of linked neurons must produce the successive excitation of motoneurons (Mns) and then the sequential activation of muscle through excitatory connections. Inhibitory connections have also been envisioned but never evidenced at the membrane level of the swallowing neurons. We investigated, by intracellular recordings, the behavior of 96 Mns in the rostral nucleus ambiguus during swallowing induced by application of superior laryngeal nerve stimulation to anesthetized sheep. The Mns were identified by antidromic activation following stimulation of glossopharyngeal, pharyngoesophageal, or cervical vagal nerves. Nine Mns showed a bell-shaped depolarization during the buccal or the early pharyngeal stage of swallowing. They probably projected to muscles of the soft palate (palatopharyngeal) and upper pharynx (stylopharyngeal, hyopharyngeal). Thirty-eight Mns exhibited a chloride-dependent hyperpolarization, indicating that they were under an active inhibition throughout the buccopharyngeal stage of swallowing. These Mns constitute a heterogeneous pool: some of them, producing spontaneous inspiratory discharges, probably innervated laryngeal or pharyngeal muscles; others might also be Mns of the esophagus, whose swallowing pattern was modified because of the anesthesia (suppression of the esophageal peristalsis). Forty-nine Mns showed a chloride-dependent hyperpolarization with a variable duration at the onset of swallowing, followed by a depolarization that could take place during either the buccopharyngeal (HD1-Mns) or the esophageal (HD2- and HD3-Mns) stage of deglutition. HD1-Mns probably projected to the median and inferior constrictors of the pharynx. HD2-Mns produced depolarizations with longer latencies and durations than those of the HD1-Mns. They probably projected to either the superior esophageal sphincter or the cervical esophagus (CE). HD3-Mns showed a buccopharyngeal hyperpolarization that was followed first by a lower-amplitude hyperpolarization accompanying the proximal CE contraction and then by a delayed depolarization. These Mns probably innervated the inferior CE or thoracic esophagus. We conclude that the initial inhibition exerted on the HD-Mns, by delaying the excitation of Mns, may play a role in the nervous mechanisms involved in temporal organization of the swallowing motor sequence. We suggest that swallowing disorders in humans such as dysphagia by failure of cricopharyngeal relaxation, diffuse esophageal spasm, and achalasia might be caused by impaired inhibitory mechanisms.

Animals↗
PubMed1992

Pregnancy complicating irradiation-induced constrictive pericarditis.

A case is reported of a 24-year-old primigravida who had severe effusive constrictive pericarditis secondary to mediastinal irradiation following chemotherapy for Hodgkin's disease. Pregnancy was threatened by serious maternal cardiovascular complications, and a non-viable fetus was born spontaneously and prematurely. Patient was completely asymptomatic before pregnancy.

Adult↗
PubMed1991

Effects of lingual nerve and chewing cortex stimulation upon activity of the swallowing neurons located in the region of the hypoglossal motor nucleus.

This study focuses on motoneurons and interneurons in the region of the hypoglossal nucleus (XIIth) related to swallowing and chewing. In sheep anesthetized with halothane, we have used extracellular microelectrodes to study the effects of stimulation of the superior laryngeal nerve (SLN), the lingual nerve (LN) and the chewing cortex (CCx) upon activities of the swallowing neurons (SNs). Ipsilateral stimulation (1-5 pulses at 500 Hz) of the peripheral afferents or CCx did not generally induce a short latency activation of the hypoglossal swallowing motoneurons (Group I SNs) since only 4 motoneurons (69 tested) were activated by the SLN, 4 motoneurons (56 tested) by the LN and none by the CCx. In contrast, the same stimulations were more effective with swallowing interneurons (Group II SNs) located in the reticular formation close to the XIIth motor nucleus since 12 neurons (30 tested) were activated with short latencies (9 +/- 1.8 ms; mean latency +/- S.D.) by the SLN, 9 neurons (21 tested) by the LN (latency; 8 +/- 1.8 ms) and 5 neurons (18 tested) by the CCx (latency: 13 +/- 1.7 ms). Seven neurons were activated by two or three modes of stimulation indicating the existence of convergent inputs upon some Group II SNs. During chewing movements induced by a prolonged stimulation (20-40 Hz) of the CCx, 10 Group I SNs (16 tested) versus only one Group II SN (8 tested) were found to fire in association with the jaw opening. Moreover, 3 motoneurons and 4 interneurons inactive during swallowing discharged during chewing movements.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1990

Axonal branching of medullary swallowing neurons projecting on the trigeminal and hypoglossal motor nuclei: demonstration by electrophysiological and fluorescent double labeling techniques.

The projections of ventral medullary reticular neurons on both trigeminal (Vth) and hypoglossal (XIIth) motor nucleus were studied in sheep anesthetized with halothane. In a first series of experiments, extracellular microelectrodes were used to record the activity of medullary swallowing interneurons (SINs) located in the ventral region (around the nucleus ambiguus) of the swallowing center. Antidromic activation after electrical stimulation of the Vth and XIIth nuclei was tested in 83 SINs. For 38 SINs a clear antidromic activation was observed and for 8 of them the response was triggered by stimulation of either nucleus. As confirmed by the reciprocal collision test, these 8 SINs had branched axons sending information to both nuclei tested. Average latencies for antidromic activation of branched SINs after stimulation of the XIIth and the Vth motor nucleus were 2.2 +/- 0.6 ms and 2.7 +/- 0.8 ms respectively. The axonal conduction velocity of these neurons was 4.4 +/- 1.3 m/s for the collateral to the Vth motor nucleus and 2.7 +/- 0.7 m/s for axons projecting to the XIith motor nucleus. In a second series of experiments the double retrograde labeling technique was used to confirm the existence of neurons with branched axons in the medullary regions corresponding to the swallowing center. Small and well localized injections of Fast Blue (FB) and Diamidino Yellow (DY) fluorescent tracers were made in the Vth and in the XIIth motor nucleus respectively. A relatively large number of double-labeled cells was found in the ventral region of swallowing center (reticular formation around the nucleus ambiguus, 2-4 mm in front of obex).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Activity of extrinsic tongue muscles during swallowing in sheep.

The participation of extrinsic muscles of the tongue in swallowing reflexly induced by stimulation of the superior laryngeal nerve was studied in 7 anesthetized sheep. The tongue retractor muscles (styloglossus and hyoglossus) always discharged in synergy with the suprahyoid (geniohyoid) and jaw (anterior digastric and medial pterygoid) muscles. The main protrusor muscle of the tongue, the genioglossus, was inactive in 5 animals and active in 2. The significance of this muscular synergy is discussed.

Animals↗
PubMed1988

Projections from the medullary swallowing center to the hypoglossal motor nucleus: a neuroanatomical and electrophysiological study in sheep.

Neurons of the hypoglossal (XIIth) motor nucleus participate in swallowing, but nothing is known of the input to these cells from swallowing interneurons (SIN) belonging to the medullary swallowing center (SC). After electrophoretic injection of horseradish peroxidase within the XIIth motor nucleus in sheep, labeled neurons were found principally in the ipsilateral ventrolateral reticular formation, 1-4 mm rostral to the obex which corresponds to the ventral region of the SC. Labeled cells were observed in the region of the nucleus of the tractus solitarius (dorsal region of the SC), predominantly when the injection site of HRP extended beyond the XIIth nucleus. The projections of ventral SIN to the XIIth nucleus was confirmed electrophysiologically. Twenty-seven of 98 tested SIN were antidromically activated (latency: 2.7 +/- 1.5 ms) by stimulating the XIIth nucleus. Twenty-one of these were histologically localized in the ventral SC, and only one in the dorsal SC. The other 5 SIN were located in the ventral group according to their stereotaxic coordinates. Our data show that SIN in the ventral reticular formation, part of the medullary SC, project to the XIIth motor nucleus; we suggest that ventral SIN are command interneurons for the different pools of motoneurons involved in swallowing.

Action Potentials↗
PubMed1987

Activity of neurons located in the region of the hypoglossal motor nucleus during swallowing in sheep.

Extracellular activity of swallowing neurons (SN) in the region of the hypoglossal (XIIth) motor nucleus was studied in sheep anesthetized with halothane. Eighty six SN exhibited a discharge closely linked to swallowing electromyographic (EMG) activity of the geniohyoïd (GH) muscle induced by stimulation of the superior laryngeal nerve. Swallowing activation persisted after motor paralysis, indicating that this activity did not result from sensory feedback. SN were classified into two groups. Group I SN (N = 66) discharged a burst of up to 12 spikes for 50-300 ms during the response of GH. Mean frequencies ranged from 10 to 60 Hz, peak instantaneous frequencies from 10 to 100 Hz. Thirty two SN were antidromically activated by stimulating the XIIth nerve. Mean latencies of antidromic spikes were 2.6 ms and 2.4 ms for SN sending their axons in the medial and lateral branches respectively of XIIth nerve, corresponding to conduction velocities of 50.4 m/s and 53.7 m/s. The other 34 group I SN were located at sites with large antidromic field potentials obscuring the identification of unitary antidromic spikes. Thirty group I SN, 16 antidromically activated and 14 in areas with large field potentials, were histologically located in the XIIth motor nucleus between the transverse planes 1 mm caudal to 2 mm rostral to the obex. Group I SN are likely motoneurons supplying GH and tongue musculature. Group II SN (N = 20) were never antidromically activated by XIIth nerve stimulation, and were all located in the reticular formation adjacent to the lateral edge of the XIIth motor nucleus, particularly in transverse planes within 1 mm of the obex.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1984

Medullary control of the pontine swallowing neurones in sheep.

The origin of the inputs from the medullary swallowing centre (dorsal region including the nucleus of the solitary tract, or ventral region corresponding to the reticular formation surrounding the nucleus ambigous) to the pontine swallowing neurones (PSNs) was studied in sheep anaesthetized with halothane. Out of 101 PSNs located in the posterior part of the trigeminal (Vth) motor nucleus, 46 were activated by stimulating either the dorsal (21 neurones) or the ventral (25 neurones) region of the ipsilateral medullary swallowing centre, 3-4 mm rostral from the obex. Thirty-one neurones out of the 46 were identified as alpha motoneurones supplying swallowing muscles (mylohyoïd, anterior body of digastric and medial pterygoïd). Their average activation latency through stimulation of the dorsal medullary region was about 1 ms longer than through stimulation of the ventral region (3.63 ms +/- 0.81 versus 2.72 ms +/- 0.32). To determine the origin of the medullary input to the PSNs, we tried to activate the medullary swallowing neurones (MSNs) antidromically through stimulating the posterior part of the Vth motor nucleus, which contains the swallowing motoneurones. Seventy-three MSNs were tested (25 located in the dorsal and 48 in the ventral region). None of the dorsal neurones tested could be antidromically activated by pontine stimulation: 15 ventral neurones showed a clear antidromic response (collision test) with an average latency of 2.5 ms +/- 0.73. These neurones, which send their axons into the pons, were all located in the reticular formation, above the nucleus ambiguus, 3-4 mm rostral from the obex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗