When a parent suffers ABI: Investigation of emotional distress in children

PRIMARY OBJECTIVE

To investigate the type of emotional and behavioural impact that having a parent with a severe acquired brain injury (ABI) has on children during the first period of adjustment.

METHODS AND PROCEDURE

The study involved 25 couples in which one of the spouses was affected by ABI, and their 35 children (3-14 years). The children attended three sessions with a psychologist aimed at identifying their spontaneous playing and relational behaviour by means of a grid created on the basis of ICD-10 criteria. Both members of each parental couple attended a session with the psychologist, and were administered the Dyadic Adjustment Scale, the 36-item Health Survey and the Caregiver Burden Inventory.

RESULTS

63% of the children showed signs of emotional suffering, the presence of which was underestimated by their parents on the basis of the psychologist's assessments. The variables that correlated most closely with the children's psychological condition were related to the quality of their parents' relationship.

CONCLUSIONS

Our findings confirm the need for early interventions aimed at both parents and their children in order to investigate the children's emotional-affective situation, and favour an understanding of their discomfort by their parents.

Acute changes in clinical parameters and thyroid function peripheral markers following L-T4 withdrawal in patients totally thyroidectomized for thyroid cancer

After total thyroidectomy, differentiated thyroid cancer (DTC) patients have to undergo L-T4 withdrawal for measuring serum thyroglobulin and 131I whole-body scan (131I WBS) to evaluate residual/recurrent malignant disease. The aim of the present work was to study in these patients the effects of acute thyroid hormone deficiency on various target organs and tissues. Clinical parameters and thyroid function peripheral markers were evaluated in 20 DTC patients, both before and after L-T4 withdrawal. A 24-h urine collection, a fasting blood sample for laboratory examinations, a clinical score for hypothyroidism and cardiovascular, neurological and neuropsychological evaluations were carried out. After L-T4 withdrawal, the clinical score significantly increased, as well as total cholesterol, triglycerides, creatine kinase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase, whereas SHBG, osteocalcin and urine hydroxyproline levels significantly decreased. The acute thyroid hormone deficiency caused a systolic dysfunction of the left ventricle associated with an increase in systemic vascular resistance without cardiac contractility alterations. A significant increase in the left ventricular mass and thickness was also observed. Carpal tunnel syndrome appeared in 30% of patients and a significant reduction in the immediate auditive memorization and in attentive performance was also detected. These observations indicate that acute hypothyroidism causes significant clinical alterations of peripheral tissue function. In the follow-up of DTC patients, therefore, L-T4 withdrawal procedure should be restricted to cases where the cost/benefit ratio is favorable. Alternative procedures, such as the use of recombinant human TSH, should be used whenever possible.

Stress of routine follow-up in colorectal cancer operated patients

Postoperative follow-up is the logical consequence of cancer treatment, but colorectal cancer follow-up does not achieve all its goals. These unfavourable findings induced us to assess whether follow-up also causes negative psychological stress in our colorectal cancer patients. In this trial 100 colorectal cancer follow-up patients were asked to compile three questionnaires: 1) the McGil Pain Questionnaires; 2) Profile of Mood Status; and 3) Locus of Control. The questionnaires were handed to the patients at follow-up and were compiled immediately. In addition, the patients were asked to answer the firsts two tests spontaneously 30 days after follow-up and mail the questionnaires. Our results showed that only 41% of the patients complied the tests 30 days after follow-up. The scores for pain and mood disorders were greater in women, especially during the "before follow-up" period. The third test revealed a prevalence of subjects with internal-type reinforcement. Our data revealed that: 1) patients tend to repress the problem; 2) women are affected by greater stress and anxiety; 3) subjects with internal-type reinforcement have a positive attitude during follow-up and this enables the ego to bear the anguish, process it and dilute it to anxiety, thus favouring future life experiences.

Modulatory action of noradrenergic system on spinal motoneurons in humans

Previous findings in animals demonstrated that the noradrenergic coeruleospinal system exerts a tonic facilitation on spinal reflexes and that activation of alpha2-autoinhibitory receptors can be responsible for a disfacilitation of the spinal activity. To investigate this issue further, we examined whether this system is also involved in descending facilitatory control of spinal motoneurons in healthy humans. The H-reflex technique was utilized to assay the motoneuronal excitability. The ratio between the maximal reflex response (H) and maximal direct response (M) was determined in each subject and was calculated at 10 min intervals before and after i.v. administration of the alpha2-agonist clonidine (0.5 microg/kg). In all subjects a marked decrease of the H/M ratio, due to depression of the H response, occurred 10 min following the clonidine injection and reached its maximum within 30 min. No significant changes of blood pressure values were provoked by drug injections. These results suggest that an autoinhibitory action may be induced by alpha2-receptor activation of locus coeruleus neurons in humans, and that this device may serve as a mechanism for a myotonolytic action on spinal motoneurons.

Immunohistochemical modifications of vasoactive neuropeptides and excitatory amino acids in the nervous tissue of the Mongolian gerbil after transient cerebral ischemia

Modifications in the tissue concentration of vasoactive peptides (Endothelin, Calcitonin Gene Related Peptide, Atrial Natriuretic Peptide) and excitatory amino acids (glutamate, aspartate) were found in the nervous tissue of Mongolian gerbils after transient cerebral ischemia which was induced by unilateral occlusion of the common carotid artery for 30 min 4 h. In fact, immunostaining for these peptides was more intense in the ischemic tissue: the greatest increases of tissue immunoreactivity were observed for Endothelin; smaller differences were found for Calcitonin Gene Related Peptide and Atrial Natriuretic Peptide. Immunostaining for Neuropeptide Y, another vasoactive neuropeptide, was virtually unchanged. Infarct areas, when present, contained numerous Endothelin-immunoreactive cell bodies. On the contrary, the same areas were completely void of glutamate- or aspartate-immunostained neurons, normally present in the correspondent regions of the control tissue. The present results suggest that severe cerebral ischemia is paralleled by an unbalance of local vasoactive factors. The predominance of vasoconstrictor action of Endothelin might play a major role in the irreversible damage, together with the excitotoxic effect of the extracellular accumulation of excitatory amino acids, probably due to a leakage from neuronal cell somata, as suggested by the disappearance of glutamate- or aspartate-immunostained neurons.

Motor cortex modulation of exteroceptive information at bulbar and thalamic lemniscal relays in the cat

We have studied the control of the primary motor cortex on the activity of lemniscal neurons in semi-chronic implanted cats. In each experiment, two to three foci in the primary motor cortex were identified by intracortical microstimulation at low threshold (up to 20 microA) for their capacity to evoke movements of contralateral single limb joints. Neurons belonging to the dorsal column nuclei (main cuneate nucleus and gracile nucleus), or to the ventral posterolateral nucleus, were sampled for their response to stimulation of the peripheral cutaneous fields, as well as the antidromic response to stimulation of the contralateral medial lemniscus and ipsilateral somatosensory cortex, respectively. These neurons were then tested for stimulation of the cortical foci using a current intensity equal to the threshold needed to evoke motor effects, although we reduced the duration of the stimulating trains; thus, we avoided evoking movements which could elicit afferent volleys along the somatosensory paths. It was found that the primary motor cortex was able to modulate the transmission of exteroceptive signals at the level of both dorsal column nuclei and ventral posterolateral nucleus with analogous modalities. In particular: (i) a high percentage of responses, with a prevalence of excitatory effects, was observed when the receptive field of the neurons topographically corresponded to, or was very close to, the joint controlled by a given cortical focus; (ii) in these cases, higher percentages of excitations were observed in tests which concerned the distal segments of limbs than the proximal segments; (iii) the percentage of responses became lower as the neuronal receptive field was located further from the cortical motor target, the pattern being more frequently inhibitory in nature. From a functional point of view, the motor cortex control appears to be organized in a very precise manner. Its excitatory nature might subserve integrative mechanisms by which exteroceptive information arising in a given limb segment would be enhanced by a motor command inducing movements of the same body part. Moreover, a better definition of the afferent input could be obtained by a simultaneous depression of neurons, which send towards the cortex signals from adjacent or more distant cutaneous regions. It can be hypothesized that such an organization of the cortical control could improve the discriminative somatosensory aspects during the execution of explorative movements, besides supplying a sharper cutaneous feedback to the motor cortex.

Excitatory amino acids as neurotransmitters of corticostriatal projections: immunocytochemical evidence in the rat

The retrograde transport of a tracer has been combined with peroxidase immunocytochemistry to verify whether corticostriatal (CS) neurons contain in their cell bodies high levels of glutamate (Glu) and aspartate (Asp). Injections of WGAapoHRP-Au in the caudate/putamen of adult rats produced retrograde labeling of a large number of layer V neurons of wide regions of the ipsilateral cerebral cortex; fewer labeled neurons were also found on the contralateral side. In all experiments, most CS neurons were seen in the agranular frontal cortex, in both the medial and the lateral subdivisions. Moreover, numerous retrogradely labeled neurons were observed in the cingulate cortex and in the granular parietal cortex, depending on the location of the injection site in the various experiments. The majority of CS neurons examined were immunostained using antibodies against glutaraldehyde-conjugates of Glu or Asp. Glu immunopositive neurons resulted 52-61% of CS neurons. Asp immunopositive neurons ranged between 53% and 62%. In the cortical tissue where Glu and Asp antisera were visualized simultaneously, up to 96% of the CS neurons were immunostained. The latter finding indicates that the populations of Glu and Asp immunopositive neurons are largely segregated and that virtually all cortical neurons projecting to the striatum contain high concentrations of Glu and/or Asp, thus corroborating the hypothesis that CS projections use excitatory amino acids as neurotransmitters.

Effects of cortical stimulation on red nucleus neurons in the guinea pig

The aim of the present work was to study the control that the cerebral cortex exerts on red nucleus (RN) neurons in the guinea pig. The experiments were carried out in anaesthetized animals. Electrical stimulation of localized cortical foci was performed by tungsten microelectrodes in frontal and parietal regions containing sensorimotor representations of the body. Single unit RN activity was extracellularly recorded through glass micropipettes, and the encountered RN neurons were recognized by searching their peripheral receptive field. Then, corticorubral influences were tested on RN neurons whose receptive field was located in the same body regions where motor responses were evoked by cortical stimulation. The stimulation with a single pulse evoked complex responses, typically consisting of long lasting inhibitions sometimes preceded by a weak facilitation and always followed by an excitatory rebound. The application of a second pulse modified this pattern, depending on the time interval between the two stimuli. In fact, the reduction of the interval below 300 ms enhanced the excitatory components whereas it shortened the inhibitory component; moreover, an "early" facilitation was evoked but only at intervals as short as 50-150 ms, or less. These results suggest that the corticorubral control may vary according to different levels of cortical activation, becoming more and more facilitatory as the cortical discharges increase from low frequency values (tonic activity) towards high frequency values (phasic activity).

Effect of nedocromil sodium on allergen-induced airway responses and changes in the quantity of airway smooth muscle in rats

BACKGROUND

Allergen exposures induce growth of airway smooth muscle in the Brown Norway rat.

OBJECTIVE

The purpose of the study was to examine the role of mediators associated with the early and late responses in the induction of airway smooth muscle growth.

METHODS

Nedocromil sodium was administered to block early and late responses in ovalbumin-sensitized and ovalbumin-challenged rats undergoing single or multiple challenges (5 times at 5-day intervals) with ovalbumin. Airway smooth muscle was quantitated by morphometry on lungs removed 2 days after the final challenge.

RESULTS

Nedocromil sodium administered before ovalbumin challenge blocked both the early and late responses. When administered 2 hours after ovalbumin challenge, it also blocked the late response. Rats undergoing challenge with aerosolized ovalbumin five times at 5-day intervals were also treated with nedocromil before (n = 10) or 2 hours after (n = 10) each ovalbumin inhalation, respectively. The quantity of airway smooth muscle standardized for size was greater after ovalbumin challenge (0.069 +/- 0.005) compared with saline controls (0.033 +/- 0.003, p < 0.005). Nedocromil significantly reduced the airway smooth muscle (0.036 +/- 0.003, p < 0.005) when administered before ovalbumin. However, the airway smooth muscle in rats that received nedocromil 2 hours after ovalbumin challenge (0.046 +/- 0.003), although lower than in ovalbumin-challenged rats (p < 0.01), was still significantly higher than in saline-treated rats (p < 0.05).

CONCLUSIONS

Allergen-induced early responses, late responses, and airway inflammation are antagonized by nedocromil. The mediators of both the early and late responses contribute to allergen-induced airway smooth muscle growth, a process that can be prevented by administration of nedocromil.

Effects of ketotifen on airway responses to allergen challenge in the actively sensitized brown Norway rat

The purpose of the study was to examine the effect of ketotifen on the airway responses and the recruitment of the inflammatory cells into the airways of sensitized rats after antigen challenge. Twenty-five Brown Norway rats, 7-9 weeks old, were actively sensitized to ovalbumin (OA) (1 mg s.c.) and Bordetella pertussis vaccine (10(9) bacilli i.p.). At 14 days after sensitization rats were anesthetized with urethane (1.1 g/kg i.p.) and intubated endotracheally. Aerosols of OA (5% W/V in saline for 5 min) were administered to control rats (Group A; n = 9), to a low-dose ketotifen group (Group B; 1 mg/kg PO; n = 8) and a high-dose ketotifen group (Group C; 10 mg/kg; PO for 10 days; n = 9). Pulmonary resistance (RL) was measured at baseline, and every 15 min for up to 8 h after OA. The magnitude of the early response was 241 +/- 51% in A (% baseline RL; mean +/- SE), and significantly less in B(119 +/- 7%) and C(131 +/- 16%) (p < 0.01). The late response was significantly lower in C than A but not B. The total cell number in bronchoalveolar lavage at 8 h after OA challenge was significantly higher in A than B and C (p < 0.01). The lymphocyte and eosinophil counts were reduced in B and C compared to A (p < 0.05). A positive correlation was found between the late response and total number of cells recovered in the BAL (r = 0.78) (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of upper and lower airway responses of two sensitized rat strains to inhaled antigen

The purpose of the study was to investigate the relationships between upper airways responses and pulmonary responses of two strains of highly inbred rats to inhaled antigen. To do this we measured the upper and lower airways resistance for 60 min after challenge of Brown-Norway rats (BN; n = 13) and an inbred rat strain (MF; n = 11), derived from Sprague-Dawley, with aerosolized ovalbumin (OA). Rats were actively sensitized with OA (1 mg sc) using Bordetella pertussis as an adjuvant. Two weeks later the animals were anesthetized and challenged. Tracheal pressure, esophageal pressure, and airflow were measured, from which total pulmonary resistance was partitioned into upper airway and lower pulmonary resistance (RL). The peak upper airway response to inhaled OA was similar in BN (1.89 +/- 0.66 cmH2O.ml-1.s; n = 7) and MF (2.85 +/- 0.68 cmH2O.ml-1.s; n = 6). The lower airway response to OA challenge was substantially greater in BN, and RL changed from 0.07 +/- 0.01 to 0.34 +/- 0.13 (n = 6; P < 0.05). The MF did not have any significant increase in RL after challenge; the baseline RL was 0.12 +/- 0.02 and only reached a peak value of 0.15 +/- 0.05 (n = 5; P = NS). Lower airway responsiveness of BN (n = 10) to serotonin, an important mediator early allergic airway responses, was similar to MF (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of interleukin-2 on the airway response to antigen in the rat

To evaluate the hypothesis that lymphocyte stimulation can modify the bronchoconstrictive response to inhalational challenge with an allergen, we administered interleukin-2 (IL-2), an important lymphokine in lymphocyte activation and proliferation, to actively sensitized rats. Brown Norway rats received either human recombinant IL-2 (n = 8) or its vehicle (n = 7) twice a day from the ninth to the fourteenth day after active sensitization to ovalbumin (OA) and were challenged with an aerosol of OA. Lung resistance (RL) during the early response increased to a maximum of 698 +/- 230% and 180 +/- 26% of baseline values in the animals receiving IL-2 and vehicle, respectively (p less than 0.025). The late response was threefold greater in IL-2-treated than in vehicle-treated animals (p = 0.01). IL-2 increased OA-specific IgG levels in the serum, but it did not significantly affect total or specific IgE levels. IL-2 caused an inflammatory infiltrate around the airways with significant increases in eosinophils, lymphocytes, and mast cells prior to antigen challenge. Our results indicate that stimulation of cell-mediated immunity can affect airway responsiveness to antigen.

Cortical modulation of thalamo-cortical neurons relaying exteroceptive information: a microstimulation study in the guinea pig

The nature and organization of cortical influences on somatosensory thalamic neurons were investigated in the guinea pig in order to ascertain if mechanisms subserving sensory-motor integration in the thalamus are as precise as has previously been demonstrated in the agranular frontal cortex (AGr) and granular parietal cortex (Gr). The study was carried out on 14 chronically-implanted awake animals. In each experiment one or two motor foci within AGr and Gr were identified according to the region of the movement evoked by intracortical microstimulation at the lowest threshold stimulation (usually 5-15 microA). Spontaneous activity of 182 thalamo-cortical single neurons was recorded in the nucleus ventralis thalami (VT). The neurons were also identified by their response to activation of cutaneous receptive fields (RFs) located in regions of vibrissae or limbs, and then tested for cortical stimulation with a pulse intensity equal to the threshold for evoking motor effects. During the cortico-thalamic tests, the duration of stimulating trains was reduced in order to avoid the appearance of limb or vibrissa movements which could activate somatosensory ascending pathways forwarding peripheral messages to VT. The cortical control on VT neurons appears to be organized in a very precise manner. It was seen that: 1) The influences on these neurons relaying exteroceptive signals specifically emanated from AGr and Gr areas which in turn received exteroceptive input. 2) The vibrissa units responded to stimulation of foci in either AGr or Gr but the reactivity was greater upon stimulation of Gr than AGr. The incidence of responses was very high when the vibrissa RF was overlapping or adjacent to the region of the cortically-evoked vibrissa movement. The response pattern was mostly excitatory. Responses were rarely observed when vibrissa RF lay distant from the vibrissa moved by cortical stimulation. 3) Neurons with limb RFs responded constantly to stimulation of Gr foci only when the RF was overlapping or adjacent to the region of the cortical motor target; in these two conditions the response pattern was excitatory and inhibitory, respectively. Inhibitions only concerned neurons with forelimb RFs. Responses to stimulation of AGr were rarely obtained. From a functional point of view, the excitatory nature of the cortical control on thalamo-cortical VT neurons suggests that a cortical signal inducing movement of a given body part is able to enhance the afferent transmission of somatosensory messages arising in the same body part.(ABSTRACT TRUNCATED AT 400 WORDS)

Structural changes in the airways of sensitized brown Norway rats after antigen challenge

The purpose of this study was to quantitate the structural changes in the airways of sensitized rats after repeated challenge with aerosolized antigen and to examine the relationship between these changes and alterations in responsiveness to methacholine (MCh). We studied 28 Brown Norway rats that were actively sensitized to ovalbumin (OA). Responsiveness to aerosolized MCh was quantitated as the concentration of MCh required to double pulmonary resistance (EC200 RL). The EC200 RL was determined before and 1 and 5 days after three inhalational challenges with OA (n = 17) or saline (n = 11) at 5-day intervals (on Days 14, 19, and 24 after sensitization). Responsiveness to MCh increased after OA; EC200 RL fell from 1.71 to 0.71 mg/ml at 1 day (p less than 0.01) and 0.87 mg/ml at 5 days (p less than 0.02) after OA but did not change after saline challenge. Formalin-fixed lungs from a sample of OA-challenged (n = 12) and saline-challenged (n = 6) animals were paraffin embedded, and 5-microns sections were stained with hematoxylin-phloxin-saffron. Cross-sectional areas of the airway wall and smooth muscle (ASM) were determined for all intrapulmonary membranous airways. There was an approximately twofold increase in the quantity of airway smooth muscle in airways of OA-challenged animals compared with saline-challenged control animals. Airway wall area did not change significantly. There was a correlation (r = 0.618, p less than 0.05) between the quantity of ASM in large airways (basement membrane length 2.00 to 2.99 mm) and change in responsiveness to MCh.

Lymphokine-induced airway hyperresponsiveness in the rat

We evaluated the potential role of the lymphocyte in chronic airway inflammation and responsiveness by repeated administration to rats of interleukin-2 (IL-2), the principal lymphokine responsible for lymphocyte proliferation. Lewis rats (mean weight, 184 +/- 2 g) received either 120,000 units of IL-2 (n = 10) or vehicle (n = 7) subcutaneously twice a day for 4.5 days. Animals were anesthetized with urethane and intubated for measurements of pulmonary resistance (RL) and airway responsiveness to aerosol methacholine (MCh). Lung lavage was performed, the animals were exsanguinated, and the lungs were fixed in 10% formalin. Histologic edema and the extent of infiltration of the bronchi, pulmonary veins, and arteries by cells was scored blindly. IL-2 increased airway responsiveness to MCh; the concentrations of MCh causing a doubling of RL were 0.14 versus 1.39 mg/ml (geometric mean) for the IL-2 and vehicle group, respectively (p = 0.001). IL-2 significantly increased total cellular return and the percentage of lymphocytes, neutrophils, and eosinophils in lavage. IL-2 caused edema and a mixed cellular infiltration of the bronchovascular tree. Lymphocytes predominated around the airways and veins. A correlation (r = 0.50) was present between airway responsiveness and airway inflammation but not with edema or vascular infiltration. Release of IL-2 by lymphocytes in the airways may be an important mediator of airway hyperresponsiveness.

Acute effects of interleukin-2 on lung mechanics and airway responsiveness in rats

We studied the acute effects of interleukin-2 (IL-2), the principal lymphokine responsible for lymphocyte proliferation, on lung mechanics and airway responsiveness to methacholine (MCh) in rats. Lewis (n = 12) and Fisher 344 (n = 13) rats were anesthetized and intubated, and intravenous and intra-arterial lines were inserted. IL-2 (750,000 U/kg) was infused intravenously over 2 to 4 min into seven Lewis and seven Fisher rats, and vehicle alone was administered to five Lewis and six Fisher rats. Blood pressure, heart rate, respiratory frequency (f), tidal volume (VT), minute ventilation (VE), and lung resistance (RL) were measured before and every 5 min for 45 min after the infusion of IL-2. Lung compliance was measured before and 30 min after IL-2. Bronchial provocation testing with MCh was performed 45 min after the infusion of IL-2. Subsequently, the animals were exsanguinated, and the lungs were removed for histologic examination. Infused IL-2 did not alter heart rate or blood pressure, VT, f, VE, and RL increased significantly by 15 min (p less than 0.05), but they returned to baseline by 45 min. Lung compliance decreased significantly in both rat strains. IL-2 increased airway responsiveness only in Lewis rats; the concentration of MCh that caused a doubling of RL (EC200RL) was 0.6 mg/ml and 4.3 mg/ml (p = 0.003) in IL-2-treated and control rats, respectively. The airway responsiveness did not change significantly in Fisher rats; EC200RL was 0.13 and 0.35 mg/ml for IL-2-treated and control rats, respectively (p = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Morphometry of the airways during late responses to antigen challenge in the rat

To quantitate the structural changes in the airways that contribute to the late bronchial response (LR) to antigen challenge we killed six Brown-Norway rats, sensitized to ovalbumin (OA) and challenged by aerosol, during the LR and compared the dimensions of the intraparenchymal airways with those of six control animals. Lungs were rapidly frozen with liquid nitrogen and fixed in Carnoy's solution. Paraffin sections were stained with hematoxylin-phloxine-saffron. At the time of the LR (382 +/- 39 min after OA challenge), RL increased from the baseline value (0.067 +/- 0.034 cm H2O.ml-1.s) by 0.107 +/- 0.03 cm H2O.ml-1.s (p less than 0.05). RL did not change significantly in the control rats. The lumen size and the wall area of all membranous airways were measured and were corrected for airway size by dividing by the basement membrane length squared (BM2). There was no increase in airway wall area in OA-challenged animals. However, the lumen of large airways (BM: 2.0 to 2.99 mm) was significantly less for the OA-challenged animals (0.039 +/- 0.0055 mm2) than for the control animals (0.058 +/- 0.0063 mm2; p less than 0.05). In six additional rats, the distribution of mast cells (MC) in the bronchial tree was determined. Tissues were fixed with Carnoy's solution and stained with a modified May-Grunwald-Giemsa stain. There were significantly more MC in the large airways than in medial or small airways. We conclude that smooth muscle constriction of large airways and not airway wall edema accounts for the LR in the rat. The distribution of the mast cells corresponds closely to the site of bronchoconstriction.

Endogenous opioids modulate the increase in ventilatory output and dyspnea during severe acute bronchoconstriction

The aim of this study was to evaluate whether endogenous opioids are involved in the regulation of breathing pattern and respiratory drive during bronchoconstriction induced by methacholine (MCh). We studied six male asymptomatic asthmatics 18 to 35 yr of age. In a preliminary study we determined the concentration of MCh causing a 60% fall in FEV1 (PC60 FEV1). On two subsequent days, we measured breathing pattern, dyspnea sensation (Borg scale), mouth occlusion pressure (P0.1), and FEV1 before and 10 min after an intravenous injection of either naloxone (0.1 mg/kg) or saline according to a randomized double-blind crossover design. A MCh concentration equal to the PC60 FEV1 was then inhaled, and measurements were repeated 5 min later. Neither placebo nor naloxone affected baseline breathing pattern, P0.1, and FEV1. Naloxone pretreatment did not influence airway response to MCh; the mean percent fall in FEV1 was 65.9 +/- 1.3 and 64.7 +/- 1.2% (mean +/- 1 SE) on the placebo day and the naloxone day, respectively. After MCh inhalation no significant changes in VE, VT, and breathing frequency occurred when patients received placebo. However, P0.1 increased from 1.48 +/- 0.17 to 3.43 +/- 0.70 cm H2O (p less than 0.05), and VT/TI fell from 0.66 +/- 0.08 to 0.52 +/- 0.04 L/s (p less than 0.05). Naloxone pretreatment resulted in an increase in breathing frequency (from 18.2 +/- 1.7 to 22.8 +/- 2.6 breaths/min; p less than 0.05) and VT/TI (from 0.58 +/- 0.06 to 0.74 +/- 0.05 L/s; p less than 0.05) after MCh.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of leukotriene D4 in the early and late pulmonary responses of rats to allergen challenge

To examine the role of leukotriene D4 (LTD4) in early and late pulmonary responses to antigen, we evaluated the effects of two LTD4, antagonists, MK-571 and FPL-57231, on the changes in pulmonary resistance (RL) in the 8-h period following antigen challenge of allergic rats. A total of 69 rats, aged 6 to 8 wk, were sensitized to subcutaneous ovalbumin (OA, 1 mg) and intraperitoneal Bordetella pertussis vaccine (6 x 10(9) bacilli). At 14 days after sensitization, rats were anesthetized with intraperitoneal urethane (1.1 g/kg) and intubated endotracheally. Aerosols of OA (5% wt/vol in saline for 5 min) were administered to 24 control rats, to 11 rats that were pretreated with aerosolized FPL-57231, and to 8 rats that were pretreated with MK-571; 6 rats also received MK-571 at 2 h after OA. A control group of 13 rats was challenged with aerosols of saline. We defined an early response (ER) as an increase in RL to at least 150% of the postsaline value occurring within 1 h after OA challenge. A late response (LR) was defined as a value of RL exceeding the mean plus 2 SD of all values of RL from 75 min to 8 h after OA challenge and lasting at least 30 min. An ER was observed in 17 of 24 control rats, in 8 of 11 FPL-57231-pretreated rats, and in 3 of 8 MK-571-pretreated rats (not significant). The magnitude and duration of the ER were significantly reduced by MK-571, whereas only the duration was affected by FPL-57231.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple representations of the body and input-output relationships in the agranular and granular cortex of the chronic awake guinea pig

The organization of somatosensory input and the input-output relationships in regions of the agranular frontal cortex (AGr) and granular parietal cortex (Gr) were examined in the chronic awake guinea pig, using the combined technique of single-unit recording and intracortical microstimulation (ICMS). AGr, which was cytoarchitectonically subdivided into medial (AGrm) and lateral (AGrl) parts, also can be characterized on a functional basis. AGrl contains the head, forelimb, and most hindlimb representations; only a small number of hindlimb neurons are confined in AGrm. Different distributions of submodalities exist in AGr and Gr: AGr receives predominantly deep input (with the exception of the vibrissa region, which receives cutaneous input), whereas neurons of Gr respond almost exclusively to cutaneous input. The cutaneous or deep receptive field (RF) of each neuron was determined by natural peripheral stimulation. All studied neurons were activated by small RFs, with the exception of lip, nose, pinna, and limb units of lateral Gr (Grl), for which the RFs were larger. Microelectrode mapping experiments revealed the existence of three spatially separate, incomplete body maps in which somatosensory and motor representations overlap. One body map, with limbs medially and head rostrolaterally, is contained in AGr. A second map, comparable to the first somatosensory cortex (SI) of other mammals, is found in Gr, with hindlimb, trunk, forelimb, and head representations in an orderly mediolateral sequence. An unresponsive zone separates the head area from the forelimb region. A third map, with the forelimb rostrally and the hindlimb caudally, lies adjacent and lateral to the SI head area. This limb representation, which is characterized by an upright and small size compared to that found in SI, can be considered to be part of the second somatosensory cortex (SII). A distinct head representation was not recognized as properly belonging to SII, but the evidence that neurons of the SI head region respond to stimulation of large RFs located in lips, nose, and pinna leads us to hypothesize that the SII face area overlaps that of SI to some extent, or, alternatively, that the two areas strictly contiguous and the limits are ambiguous, making them difficult to distinguish. The input-output relationships were based on the results of RF mapping and ICMS in the same electrode penetration. The intrinsic specific interconnections of cortical neurons whose afferent input and motor output is related to identical body regions show a considerable degree of refinement.(ABSTRACT TRUNCATED AT 400 WORDS)

The site of airway responses to methacholine or antigen inhalation challenge

We evaluated changes in upper airway and lower pulmonary resistance after methacholine or ovalbumin challenge in inbred rats. Methacholine or antigen were inhaled through the intact upper airway and through a tracheostomy, in two groups of normal sensitized animals. Methacholine challenge resulted in both upper airway and lower pulmonary resistance increase regardless of the inhalation route. Lower airway ovalbumin challenge caused an increase in lower pulmonary resistance with no change in upper airway resistance. By contrast ovalbumin inhalation through the nose provoked a striking increase in upper airway resistance. Atropine pretreatment of lower airways reduced lower pulmonary response to antigen. We conclude that: 1) the increase in upper airway resistance following methacholine challenge occurs through a reflex mechanism; 2) upper airway constriction following antigen challenge through the nose results from a local mechanism; 3) the site of airway constriction depends on local mechanisms and vagal reflexes.

Convergence pattern of cortical and interposital influences on rubrospinal neurons of the cat

In adult semi-chronically implanted sedated cats discharges of single rubrospinal (RS) neurons were tested for selective activation of movement-evoking foci within pericruciate cortex (CX; area 4) and anterior division of cerebellar interpositus nucleus (IN). It was found that a very high incidence of neuronal responses was obtained only when stimulating IN and CX foci which controlled the same joint with respect to that moved from activation of the rubral foci including the recorded neurons. In these cases very frequent convergence phenomena were observed by activating IN and/or CX foci. Analysis of response patterns showed that RS neurons included in a focus controlling a given muscle were excited by IN foci for the same muscle (agonist foci) and inhibited from IN foci for the antagonist muscle (antagonist foci). In contrast, the same RS neurons were inhibited by agonist CX foci and excited by antagonist CX foci. Such an organization suggests that the motor cortex plays a competitive role in modulating the action of the interposito-rubrospinal system.

[Simultaneous registration of rheographic and manometric parameters of the inferior esophageal sphincter in the cat]

The aim of the present study was to detect simultaneously hemodynamic parietal events and intraluminal pressure of the Lower Esophageal Sphincter (LES), with particular regards to cyclic changes due to systo-diastolic cardiac activity. A probe for combined Intraluminal Manometric Plethysmography (IMP) and Intraluminal Impedence Plethysmography (IIP) was used. It was a Swan Ganz bipolar pacing catheter, modified by removing the latex balloon from the tip. The exposed side-hole (diameter smaller than 0.5 mm) was utilized as a terminal orifice for an infused manometry system. It was preliminarly essayed in bench tests. A perfusion rate of 1.75 ml/min was chosen as it did not induce significant elevations of the pressure base-line and allowed detection of pressure rise rates up to 300 mm Hg/s. The two metallic rings, originally designed for intracardiac stimulation, were used as low resistance electrodes to record impedence variations. Since very small shifts of recording electrodes induce important artifacts, the present experiments were carried out on curarized cats. In these conditions, artificial ventilation could be temporarily stopped to avoid any artifact due to respiration mechanics. The proposed method seems to be satisfactory enough for simultaneous acquisition of IIP and IMP data at LES level. Recordings of IIP allow to reveal changes in parietal blood content which could chiefly be referred to lamina propria and submucosa districts. On the other hand, IMP cyclic fluctuations would signal variations of total sphincteric tension, likely depending on hemodynamic events in all vascular beds of the wall. In our opinion, a more extensive analysis of IMP and IIP waves, as well as of reciprocal relationships between rheografic and manometric parameters, may provide very useful knowledges on sphincteric physiology.

Effect of microstimulation of movement-evoking cortical foci on the activity of neurons on the dorsal column nuclei

Cortical foci in which stimulation produced movement in either the forelimb or hindlimb were isolated in rats. In each experiment, two foci were selected: one for movement in the forelimb, and the other in the hindlimb. Stimulation was subsequently reduced in order to avoid eliciting a movement, and the effects of this stimulation on activity of gracile and cuneate neurons were examined. Both excitation and inhibition were observed and were found to be arranged in a somatotopic manner. Excitation was almost exclusively obtained when the receptive field (RF) of a given neuron corresponded to the body surfaces overlying the joints involved in the cortically evoked movement. A high percentage of neurons with RFs on body surfaces corresponding to, or adjacent to, the region of cortically induced movement were inhibited, while the activity of neurons with RFs distant to the site of movement was seldom modified. These results suggest that cortical influences exerted on the dorsal column nuclei (DCN) in rats are organized in a somatotopic manner.

[Influence of the sensorimotor cortex on single neurons of the nucleus gracilis in the cat]

The aim of this study was to investigate the functional role of the cortical projections to gracile nucleus. In unanesthetized cats single nuclear units projecting to the thalamus were tested for microstimulation of cortical foci (area 4) able to evoke single joint movements in contralateral hindlimb. A very significant percentage of gracile cells was influenced, very often in excitatory manner, if their receptive field was overlaying or very close to the joint controlled by a given cortical focus. Conversely, when the location of the receptive field was more distant, the percentage of responses and the incidence of excitatory effects decreased, inhibitions occurring more frequently. From a functional point of view, such an organization of the cortico-gracile control could be effective in modulating transmission of exteroceptive information from the region of the motor target (facilitation) as well as from adjacent ones (suppression). This arrangement could provide an higher resolution of afferent messages, in relation with the cortically induced movements.

Interpositus nucleus influences on pyramidal tract neurons in the cat

The influences of the interpositus nucleus on pyramidal tract neurons were investigated by stimulating, in unanesthetized cats, interpositus nucleus foci which activated single muscles in limbs, while recording unitary discharges of pyramidal tract neurons located in foci (area 4 gamma) from which contraction was obtained in the same muscles as those excited from interpositus nucleus (agonist pyramidal tract neurons), in their antagonist (antagonist pyramidal tract neurons), or in heteronymous muscles (heteronymous pyramidal tract neurons). It was found that agonist pyramidal tract neurons were inhibited from the interpositus nucleus, whereas antagonist pyramidal tract neurons displayed a pure excitatory or an excitatory-inhibitory pattern, and the heteronymous neurons were not significantly influenced. A direct activation of interposito-thalamic efferents could be responsible for these effects. In fact, unitary discharge changes of pyramidal tract neurons, elicited from interpositus nucleus stimulation, persisted after chronic intermediate cortex ablation and dentate nucleus lesions, and disappeared following coagulations in the ventrolateral nucleus of the thalamus. These results suggest that interpositus nucleus efferents, which activate a given muscle, via the rubrospinal pathway, could inhibit the discharge of pyramidal neurons controlling that muscle, via collaterals direct to the thalamic ventrolateral nucleus.

Relationship between input and output of cells in motor and somatosensory cortices of the chronic awake rat. A study using glass micropipettes

Experiments using the same glass microelectrode (6--8 M omega) for recording and stimulating were performed on 12 rats in which 379 cortical cells were studied in 65 penetrations through the motor and somatosensory cortical zones. To avoid anaesthetic effects the rats were chronically implanted with a head system derived from the one developed by Noda et al. (1971). These animals well accepted head fixation and the peripheral receptive fields could thus be easily investigated. In a preliminary experiment the number of pyramidal cells activated by a given stimulus intensity was evaluated. The lowest threshold intensities were always observed in the Vth pyramidal layer, as well as correspondence between cell input and output. The same type of organization, with identical thresholds, existed in the so-called "Motor" and "Somatosensory" cortical zones. Movements could be obtained when stimulating near non-PT cells (600--700 micron below the cortical surface). However, thresholds were higher at this level and it is thought that the movements were due to a spread of the stimulating current to the pyramidal tract cell layer.

Single muscle organization of interposito-rubral projections

In unanesthetized neuraxis intact cats microstimulation of the interpositus nucleus (IN) which activated a single flexor or extensor muscle in limbs, was used to investigate changes of unitary discharged of rubrospinal (RST) cells. Recordings were made from sites the stimulation of which excited the same muscle activated by the IN (agonist cells), its antagonist (antagonist cells) or heteronymous muscles (heteronymous cells). Cats submitted to chronic cerebellar decortication, acute brachium conjunctivum (BC) section, acute prerubral hemidecerebration or chronic prerubral hemidecerebration and contralateral BC section, were used as controls. It was shown that agonist RST cells were monosynaptically fired from IN, while antagonist cells were inhibited and the heteronymous ones were not influenced. Cerebellar efferents within the BC mediate both excitatory and inhibitory effects, but cerebellar cortex and prerubral structures were not involved in their production.

Motor responses evoked by microstimulation of restiform body in the cat

Motor effects produced by microstimulation of restiform body (RB) were studied in acute unanesthetized cats, using tungsten electrodes for stimulating the peduncle and bipolar steel electrodes for recording muscular activity (EMG). The main results were the following. 1. Threshold microstimulation (18.24 microA +/- 8.77 S.D.) of effective foci within RB elicited single muscle contractions of ipsilateral limbs, primarily of forelimb; overthreshold activation (32.83 microA +/- 9.25S.D.) of the same points produced complex movements in 61.54% of cases that involved muscles of shoulder, neck, and trunk. 2. Single muscle contractions exhibited a mean latency (20.09 msec +/- 2.04 S.D.) which was significantly longer than that shown by complex movements (10.00 msec +/- 3.10 S.D.). Furthermore, a decrease in frequency of stimulating train below 300 Hz and a reduction in duration below 30 msec caused a steep rise of threshold for single muscle responses that was not observed when studying complex movements. 3. Acute RB interruption between stimulating electrode and cerebellum abolished single muscle contractions; conversely, complex movements remained unmodified even when the RB was lesioned in cats chronically submitted to interruption of brachium conjunctivum (BC). 4. The pathway involved in promoting RB induced single muscle activation includes interpositus nucleus, BC and rubrospinal tract. Possible modalities of RB afferent participation to the motor control are briefly discussed.