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PubMed2001

Reflex adaptations during treadmill walking with increased body load.

Load dependent reflex adaptations were studied in healthy subjects walking on a split-belt treadmill. Compensatory reflex responses were elicited in the right leg extensor muscles during mid-stance by a short acceleration of the right treadmill belt. Electromyographic activity (EMG) was recorded from the right medial gastrocnemius (GMR), soleus (SO) and tibialis anterior (TA) muscles of the right leg as well as from the gastrocnemius of the left unperturbed leg (GML). To study the adaptational reflex behavior, multiple measurements were taken during walking with normal (control) and increased body load and after removing the load. In most experiments the compensatory EMG response in the GMR consisted of a short inhibitory and a subsequent excitatory component. Both reflex components were larger when the body was loaded. During the course of continuous loading, divergent reflex adaptations of different degrees and directions were observed in the subjects. In one group of subjects the reflex response increased to a higher level of EMG activity. In a second group EMG activity first increased and afterwards decreased to baseline level. A subsequent removal of body loading resulted in a slow adaptation to the control reflex values in both groups. Neither the EMG activity in the GM nor the reflex responses in the GMR after increasing the load changed differently in the two groups. Our results suggest that load information is not simply used in a fixed input/output relationship of the actual biomechanical conditions of a subject. Load information is rather used to slowly modify the reflex response, to achieve the desired posture during walking.

Adaptation, Physiological↗
PubMed2002

The cord stretch receptors in the abdominal nerve cord of the crayfish Cherax destructor: physiology and relationships.

The physiology and relationships of tonic cord stretch receptor neurons in the crayfish Cherax destructor were examined with intracellular and extracellular recording. Cord stretch evoked slow depolarisations leading to action potentials in tonic cord stretch receptor neurons. Intermittent post-synaptic potentials were also seen in cord stretch receptor neurons but were not the primary cause of the action potentials. Cord stretch still evoked action potentials in cord stretch receptor neurons when all synaptic activity, monitored at another known chemical synapse, was blocked using high [Mg(2+)] and low [Ca(2+)] in the bath. One source of facilitating excitatory post-synaptic potentials in the cord stretch receptor neurons was from mechanosensory hairs on the dorsal abdominal surface. Tonic cord stretch receptor neuron activity was associated with an increase in the activity of the abdominal slow extensor inhibitor motor neuron and at least one abdominal flexor excitor motor neuron in its segment, and reduced activity in the abdominal slow flexor inhibitor motor neuron. Activation of individual cord stretch receptor neurons produced a local resistance reflex. Cord stretch, activating many receptors, produced several other outcomes. One was the "extensor state" described in earlier literature. The tonic cord stretch receptor neurons of Cherax destructor appear to be stretch-sensitive interneurons that receive inputs from other elements of the abdominal control system and mediate polysynaptic reflex activity in postural motor neurons.

Abdominal Muscles↗
PubMed2001

Paroxysmal Dyskinesia.

This group of disorders is characterized by periodic sudden events of involuntary movement. The clinical range of these involuntary movements is wide including tonic spasms, choreiform and athetoid movements and sustained dystonic postures. Confusion with reflex forms of epilepsy has been common in the past, but in general, paroxysmal dyskinesias are not associated with alterations in consciousness or epileptiform activity on electroencephalogram. The underlying basis of the paroxysmal dyskinesia is under active investigation as is their relationship to epilepsy and other paroxysmal disorders.

Journal Article↗
PubMed1979

Localization of lumbar epaxial motoneurons in the rat.

In the rat, lateral longissimus and the lumbar transverso-spinalis muscles are lumbar trunk muscles, and participate in the lordosis reflex (female sexual posturing). Medial longissimus, the remaining major lumbar epaxial muscle, is a muscle of the proximal tail-tailbase. To allow an analysis of the motor control of lordosis, motoneurons for these muscles must be localized. Horseradish peroxidase (HRP) was injected into lumbar epaxial muscles of female rats. Following injection into medial longissimus, labeled cells were found posterior to the lumbar enlargement, ventrolaterally in the ventral horn. Following injections into lateral longissimus or into lumbar transverso-spinalis muscles, most labeled cells were found on the medial side of the ventral horn, extending through and anterior to the lumbar enlargement. Injections into lumbar transverso-spinalis muscles at more posterior levels led to more posterior locations of labeled cells. The distributions of the labeled cells agree with previous observations on innervation of the muscles. Additionally, the spinal cord was scanned for sites at which microstimulation produced visible twitches of medial longissimus or transverso-spinalis muscles. Locations of low threshold twitch sites were consistent with conclusions based on the HRP findings.

Animals↗
PubMed1993

Neurologic and histologic evaluation of almitrine+raubasine (Duxil) in middle cerebral artery occlusion in cats.

Impairment of energy metabolism is the fundamental mechanism leading to cell death in ischemia. Using the middle cerebral artery (MCA) occlusion model in cats, we studied the effect of Duxil (almitrine and raubasine combination), which was given either before and after or only after MCA occlusion, on ischemia in terms of neurological function and histological changes. Neurological function was assessed consecutively for 7 days after MCA occlusion using a categorical rating scale in 18 cats. Neurological function was significantly improved in treated animals than in non-treated controls regarding to the motor and sensory function, walking, posture and stepping reflex. Animals were killed on the 8th day and histological changes were examined by light and electron microscopies. Significant improvement in the morphological scores based on the light-microscopy changes were found in animals treated with Duxil compared to non-treated ones. Under the electron microscopy, the protective effects of Duxil were characterized by retaining glycogen and mitochondria. Morphological improvement was associated with the recovery of neurological function and especially profound in penumbra areas of MCA infarction. These results suggest that Duxil has a protective effect against ischemic damage induced by occlusion of MCA in cats.

Almitrine↗
PubMed1979

Adipose cell morphology and control of lipolysis in a patient with partial lipodystrophy.

A previously unreported patient with partial (cephalothoracic) lipodystrophy is described. Glucose tolerance and plasma lipids were normal, but plasma insulin increased to 340 muU/ml during an oral glucose tolerance test. Plasma free fatty acids were appropriately suppressed by oral glucose, insulin, and nicotinic acid, and were increased by infusion of norepinephrine. The lipolytic responses was also normal in response to two stimuli for endogenous catecholamine release: upright posture and 2-deoxyglucose infusion. There was a gradual development of postural hypotension in response to upright posture despite appropriate reflex tachycardia. Anhidrosis was present over the lower half of the body during this test, in a distribution corresponding to the area of adipose tissue hypertrophy. Anhidrosis was also seen in this region in response to warm ambient temperature. Adipose cells from the atrophic area were smaller than those from the hypertropic area, but the atrophic cells were only 65% of the volume of the hypertrophic cells by two different methods. Thus, loss of cells occurred. Glucose-1(-14)C utilization and in vitro lipolysis were similar in the two cell preparations; the difference were explicable by cell size and did not suggest a metabolic abnormality. Counts of unmyelinated nerves were similar in the two areas. These findings indicate that in this patient the lipodystrophy was associated with normal fat cells and an autonomic dysfunction. However, the findings cannot completely explain the pathogenesis of her disorder. Loss of fat cells, rather than symmetrical shrinkage, occurred in the upper half of the body.

Adipose Tissue↗
PubMed1991

A neurotoxicity screening battery for use in safety evaluation: effects of acrylamide and 3',3'-iminodipropionitrile.

The effects of two known neurotoxicants, acrylamide (ACR) and 3',3'-iminodipropionitrile (IDPN), were assessed using a functional observational battery (FOB), a measurement of motor activity (MA), and neuropathology (NP) in the context of a safety evaluation study. One hundred Sprague-Dawley rats (10/sex/group) were tested initially and then doses with vehicle, ACR (10 or 30 mg/kg/day), or IDPN (50 or 125 mg/kg/day) by oral gavage 7 days/week for 5 weeks (except where otherwise indicated). Neurobehavioral assessments were conducted prior to initiating treatment at 1, 6, and 24 hr after the first dose, and weekly thereafter. Body weight and food consumption were determined weekly, and animals were observed twice daily for signs of toxicity. Blood samples were obtained at termination for routine clinical pathology studies. At termination three animals/sex/group were perfused in situ for neuropathology evaluations and the remaining animals were necropsied for standard histological evaluations. Prominent neurological signs were observed in high-dose animals after 2 weeks, and significant mortality occurred in high-dose ACR animals during Week 3. A 7- or 10-day recovery period was initiated after 20 or 22 daily doses for high-dose IDPN and ACR animals, respectively. ACR and IDPN affected body weight, body-weight gain, food consumption, general activity (horizontal and vertical), urination, muscle tone (grip strength), motor reflexes, gait, and posture. Significant sex effects were seen in animals exposed to IDPN, with males being more severely affected. Microscopic examination of nervous system tissue and selected organs revealed minimal to moderately severe axonal swelling characterized by the presence of enlarged balloon-like axons in the brainstem and the cervical and lumbar cord of IDPN-treated animals. This change was most prominent in males and most severe in the lumbar spinal cord. An increased incidence of chronic progressive nephropathy was also noted in IDPN-treated rats. ACR-treated animals exhibited minimal to moderate degeneration in the cervical and lumbar spinal cord, the gasserian and dorsal root ganglia, and the tibial, sciatic, and sural nerves which were characterized by changes in axonal diameter, increased argyrophilia of axons, and disruption, fragmentation, and distortion of axons and the myelin sheath. Granulomatous inflammation in the lungs of high-dose ACR animals resulted from inhalation of feed, most probably due to partial paralysis or incoordination during feeding.

Acrylamide↗
PubMed1986

Role of asphyxia and slow intrauterine growth in morbidity among breech delivered infants.

The outcome of breech delivery was evaluated by a neonatal neurological score and a follow-up examination at 18 months of age. The subjects were 132 children identified by ultrasound to be in breech presentation in the 33rd gestational week. 62 were born in breech presentation, while 70 turned to vertex presentation. During the early neonatal period, a neurological score was obtained based on the results of 29 items concerning posture, muscle tone, reflexes and reactions. Although there was no difference, in neurological score or in general development when the entire breech and vertex groups were compared, the SGA (small-for-gestational age) infants and the infants with low Apgar scores of the breech group had the poorest neurological scores. The contribution of certain maternal and fetal factors to postnatal condition was evaluated by a multiple linear regression analysis. Within the breech group, relationships were found between the neurological score and the variables intrauterine growth, fetal sex, and low Apgar score. A major part (66%) of the variation in neurological score was explained by the combination of these variables. These factors should therefore be taken into consideration when deciding on the mode of delivery in breech presentation.

Apgar Score↗
PubMed1983

Subdural hematomas. I. Acute subdural hematoma: progress in definition, clinical pathology, and therapy.

A series of 206 patients with clotted subdural hematomas operated within 3 days of closed head injury is presented. Sixty-two percent (128) were operated within 24 hours of trauma (acute subdural hematoma) carrying a high incidence of sterotypic motor posturing, impaired oculomotor reflexes, and unilateral dilated fixed pupil. A functional recovery occurred in 27% and a vegetative state or death resulted in 62%. The remaining 38% were operated after 24 but within 72 hours from injury (early subacute subdural hematoma) and generally had less severe neurologic dysfunction. A functional recovery occurred in 54% and vegetative state or death in 34%. The 128 acute cases are presented in detail to establish a logical basis for time differential. The cases requiring operation within 12 hours of injury were the most challenging. Improved outcome is felt to result from prompt referral and large craniotomy in the earliest hours after injury, combined with careful postoperative monitoring. Clinical, operative and autopsy findings are presented and discussed in relation to pathogenesis.

Acute Disease↗
PubMed2005

[The comatose patient].

Consciousness and wakefulness require normal functioning of the cerebral cortex, as well as of the midbrain reticular formation and its ascending projections. Bilateral structural lesions or functional disturbances of these brain areas can impair consciousness and can produce coma. The bodily posture and brainstem reflexes of the comatose patient provide clues as to whether the lesion lies in the brainstem or in the cerebral hemispheres. Brainstem reflexes are usually preserved in coma due to bilateral hemispheric dysfunction, including metabolic, anoxic, and toxic coma. Ancillary tests are used to answer specific diagnostic questions. The treatment of coma depends on its etiology.

Brain Injuries↗
PubMed1975

Neural control of renin release.

1. Factors involved in the neural control of renin release have been reviewed. 2. Experimental evidence has been obtained that sympathetic stimulation releases renin from the kidney independently of local vasomotor changes. 3. The reflex control of renin release on postural change has been established. 4. The effect of diuretics on renin release has been studied and evidence of neural and non-neural mechanisms obtained. 5. The effect of suprarenal aortic stenosis has been studied; the findings suggest that renin release is in some way dependent on neural mechanisms. 6. The pathological significance of the neural control of renin release has been discussed.

Animals↗
PubMed1995

The influence of ulnar nerve blockade on skin microvascular blood flow.

Microvascular research is seriously hampered by the great temporal and spatial variability of the measured skin blood flow and variation in sympathetic vasomotor reflexes within and between persons. Therefore skin vasomotor reflexes were studied before and after ulnar nerve blockade within the same person, resulting in a temporal complete denervation of the fifth finger and partial denervation of the fourth finger. Skin temperature and laser Doppler flux (LDF) were registrated to measure predominantly arteriovenous shuntflow. Measurements were performed on the palmar tip of the second and fifth finger in nine healthy volunteers, at baseline, and during a sympathetic reflex test (i.e. inspiratory gasp) and postural response test. Beat-to-beat digital blood pressure was recorded from the third and fourth finger by a Finapres device. Baseline capillary blood cell velocity (CBV) was measured at the nailfold of the second and the fifth finger. After ulnar blockade baseline skin temperature, LDF and CBV increased significantly, with respectively (mean +/- SE) 3.2 +/- 0.9 degrees C, 20.9 +/- 5.9 relative perfusion units and 0.79 +/- 0.40 mm-1 s. The percentage LDF decrease of the fifth finger during inspiratory gasp was 48.2 +/- 5.3% before and 3.1 +/- 0.9% after blockade. The postural response test showed a decrease in LDF of the fifth finger with no significant difference before and after blockade, respectively 12.3 +/- 14.7% and 8.0 +/- 2.7%, while no difference was found in the increase in digital blood pressure in the denervated fourth finger compared to both the same finger before blockade and to the third non-blocked finger.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1998

Postural after-contractions in man attributed to muscle spindle thixotropy.

1. It is an old observation that non-volitional arm abduction movements accompanied by a sensation of arm lightness often occur as an after-effect following forceful voluntary arm abductor contractions against a restraint. In the present study we have tested the hypothesis that such non-volitional, so-called 'postural after-contractions' are tonic reflex responses to an enhanced resting discharge in primary muscle spindle afferents which in turn is a consequence of thixotropy-dependent enhanced stiffness of intrafusal muscle fibres. 2. Results obtained in ten volunteers show that the arm abductor after-contraction phenomenon in man is most readily evoked by a type of conditioning procedure which in various respects mimics the procedure proven in animal experiments to be particularly effective in producing thixotropy-dependent excitation of primary spindle endings. 3. It is also shown that changes in arm abductor intramuscular temperature affect the strength of the after-contractions in a direction predicted by the thixotropy hypothesis. 4. Attention is drawn to several similarities between the after-contraction phenomenon with accompanying sensory illusions and the tonic reflex responses and illusions that can be induced when primary spindle endings are excited by muscle vibration. 5. The results support our hypothesis that postural after-contractions are induced by activity in primary muscle spindle afferents as a consequence of thixotropic properties of intrafusal muscle fibres. Central excitability changes following the conditioning voluntary effort may contribute to the phenomenon.

Adult↗
PubMed1992

Evaluation of captopril versus reserpine and frusemide in treating hypertensive children with acute post-streptococcal glomerulonephritis.

We have evaluated the effect of oral captopril versus a combination of oral reserpine and frusemide in the treatment of 20 children with post-streptococcal glomerulonephritis (APGN) with hypertension. Captopril produced a significantly greater reduction in systolic and diastolic blood pressure in both the standing and supine positions than reserpine + frusemide at 0.75, 1, 1.25, 8, 24, 48 and 72 h after initiating treatment. Neither postural hypotension nor reflex tachycardia accompanied the therapeutic effect of captopril. Blood urea, serum creatinine and creatinine clearance did not change significantly after therapy in either study group. Three days after initiating treatment, the 24 h urinary catecholamine output increased significantly in children who received captopril but did not change in children treated with frusemide and reserpine.

Acute Disease↗
PubMed2002

Don't throw in the towel! A case of reversible coma.

A young woman with pre-eclampsia became unresponsive shortly after delivery. Examination revealed extensive brain stem dysfunction with absent pupillary light reflexes and decerebrate posturing. Computed tomography showed hypodensity throughout the brain stem, and it was initially thought that she had suffered catastrophic brain stem infarction. However, magnetic resonance diffusion imaging and apparent diffusion coefficient mapping showed that she had brain stem vasogenic oedema (posterior reversible encephalopathy syndrome, PRES), rather than cytotoxic oedema. With antihypertensive and supportive treatment, she recovered rapidly, and had no abnormalities on repeat imaging.

Adult↗
PubMed1989

Comparison of the effects of botulinum toxin in adult and neonatal rats: neuromuscular blockade and toxicity.

A single dose of botulinum toxin (BoTX) was injected subcutaneously to induce neuromuscular blockade in the triceps surae muscles of the hindlimbs of neonatal and adult rats. The efficacy of the toxin in producing complete neuromuscular blockade of the lower limb muscles, assessed by blockade of (a) postural and flexor reflexes and (b) muscle contraction in response to nerve stimulation, was dose dependent at all ages over a BoTX dose range of 10-60 ng/kg. However, BoTX was dramatically more toxic in adult animals resulting in a decline in body weight and lethal consequences in 25% of adult animals 1 week after administration of BoTX doses as low as 40 ng/kg. In contrast, neonatal animals, given the same dosage, continued to grow and no mortalities were observed. The differences in toxicity of BoTX in adult and neonatal rats are readily accounted for by the short duration of effect in the younger animals, which, in turn, is probably the result of more rapid generation of new and functional nerve terminals.

Aging↗
PubMed2003

Hormonal-neural integration in the female rat ventromedial hypothalamus: triple labeling for estrogen receptor-alpha, retrograde tract tracing from the periaqueductal gray, and mating-induced Fos expression.

The lordosis reflex, a stereotypic posture adopted by female rats during sexual behavior, requires the convergence of a hormonal signal, estrogen, with a descending neural pathway from the ventromedial hypothalamic nucleus (VMH). The VMH contains at least three lordosis-relevant neural populations: estrogen receptor-alpha immunoreactive (ERalpha-IR) neurons, VMH neurons that project to the periaqueductal gray (PAG), and neurons that are ERalpha-IR and project to the PAG. Expression of Fos, a marker for neuronal activation, is increased in the VMH after mating. However, it is unknown which, if any, of these lordosis-relevant populations is activated. The majority of ERalpha-IR and projection neurons were not colocalized. Of the Fos-positive neurons, 41% neither contained ERalpha nor projected to the PAG, and 35% contained ERalpha but did not project to the PAG. Only 25% of Fos-positive neurons projected to the PAG, including projection neurons that expressed ERalpha. Our results suggest that mating activates several distinct VMH neuron types. However, ERalpha-IR neurons are activated to a greater extent compared with the PAG-projecting neurons.

Animals↗
PubMed1986

Indoramin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in hypertension and related vascular, cardiovascular and airway diseases.

Indoramin is a postsynaptic selective alpha 1-adrenoceptor antagonist used in the treatment of hypertension. In contrast to some other alpha-blockers, animal studies suggest that its blood pressure lowering effect results from relaxation of peripheral arterioles as a consequence of blockade of postsynaptic alpha 1-adrenoceptors. Furthermore, unlike some other alpha-blockers, this lowering of blood pressure is rarely associated with reflex tachycardia or postural hypotension. Therapeutic trials have shown indoramin to be effective in lowering blood pressure in all grades of hypertension: mild and moderate hypertension when used alone, but generally in combination with a thiazide diuretic, and in moderate to moderately severe hypertension when used in combination with a beta-blocker and diuretic. In a few small comparative studies, no significant difference was found in the blood pressure lowering effects between indoramin and methyldopa, propranolol and prazosin. Side effects were similar for indoramin, propranolol and methyldopa; however in the 1 comparative study with prazosin, prazosin produced a lower incidence of sedation. Indeed, the most common side effect with indoramin therapy has been sedation of a mild to moderate and/or transient nature, reported in about 19% of cases. Other side effects which have sometimes led to a withdrawal of indoramin treatment have been dry mouth, dizziness, and in males, failure of ejaculation; however, side effects may be reduced by starting therapy with smaller doses and titrating more gradually.

Asthma↗