Biomedical subjects
Publications and source records attributed to A Hernandez.
A major iatrogenic injury involving the bifurcation of the aorta and the inferior vena cava during lumbar disk surgery was successfully repaired by completing the near transection of the right common iliac artery, venorraphy and aortorraphy of the wounds of the bifurcation, and end-to-end anastomosis of the left hypogastric artery to the right common iliac artery.
A pyrethrin-piperonyl-butoxide shampoo was compared with a similarly formulated lotion for their pediculicidal and ovicidal effects against head lice. Forty children with active Pediculus humanus capitis infestation were randomly assigned to one of two groups for a single treatment with either the shampoo or the lotion. An average of ten nits were taken from each patient both before and after treatment. These eggs were incubated for 14 days, the resulting lice counted, and their conditions noted. Lice recovered from the rinse water after treatment were also counted and observed. Although both products proved to be effective in killing lice, the shampoo had greater ovicidal efficacy, 50% versus 25% for the lotion, after adjustment for natural mortality of the ova.
Calves were immunized twice in 4 weeks with a Fasciola/Schistosoma cross-reactive, cross-protective defined immunity antigen (denoted FhSmIII(M)) isolated from F. hepatica adult worm extracts by antibody affinity chromatography and challenged 7 weeks later with F. hepatica metacercariae. Flukes were recovered at 16 weeks of infection at which time the immunized calves had 55% less F. hepatica than the controls. All of the immunized calves developed high antibody levels of FhSmIII(M), detectable in the ELISA, by 4 weeks after a single immunization. By 9 weeks of infection with F. hepatica the immunized calves had lower sorbitol dehydrogenase levels than the unimmunized, F. hepatica-infected control calves, indicating less liver damage in the vaccinated group. These studies demonstrate that subcellular F. hepatica macromolecules cross-reactive and cross-protective against S. mansoni also have the potential to serve as vaccines in cattle exposed to this parasitic disease.
Bioelectrical responses evoked in the ventrolateral funiculus (VLF) of the spinal cord by electrical stimulation of the contralateral hind limb were studied following topical application of 1% morphine solution to the somatosensory SI area of the rat cerebral cortex. After morphine, a typical pattern was observed in the electrocorticogram, characterized by the appearance of rhythmic spiking activity. Time-related with each cortical spike, a significant reduction in the amplitude of VLF responses was observed. It is concluded that cortical excitation induced by morphine generates descending influences having the ability to inhibit spinal sensory transmission.
Molecular characterization of the alpha-thalassemia mutations present in nine HbH subjects from Cuba was achieved by digestion with Bam HI, Bgl II, and Apa I and hybridization with alpha- and zeta-specific probes. The results show that the molecular basis of the genetic defect is quite homogeneous, all the subjects carrying the - alpha 3.7 type I/--SEA genotype. Variations are observed in the size of the zeta polymorphic fragments.
LTB4 is a potent chemotactic and chemokinetic eicosanoid released by leukocytes during inflammatory reaction; in addition to this it possesses a bronchopulmonary activity in different animal species. Since cysteinyl containing leukotrienes and other eicosanoids have been shown to induce hyperreactivity of pulmonary smooth muscles, we investigated the release of LTB4 from different anatomical structures of guinea-pig lung in vitro and the possible interaction with histamine in these tissues. In fact, hyperreactivity is evidentiated by a synergism between different mediators. The ovalbumin sensitized guinea-pig lung has been brushed in order to separate lung parenchyma from bronchi and vessels which were divided into large and small preparations. The antigen challenge resulted in a statistically significant increase in LTB4 production in large bronchi and vessels, whereas in the other preparations considered the basal levels of the eicosanoid were not modified during the anaphylactic reaction. In parallel with the differential site of LTB4 release, a positive interaction between LTB4 and histamine was only observed in the pulmonary artery. These data suggest that the possible role of LTB4 in different pulmonary diseases is not confined to the airway smooth muscle but it might be related to its capacity to induce vascular hyperreactivity.
To relate the evolution of ventricular fibrillation (VF) to the haemodynamic recovery after cardioversion, we characterized the differences in the ECG power spectrum (PS) time course, among different types of VF: under control conditions, with previous administration of nifedipine and on cardiopulmonary bypass (CPB). In the first few seconds VF showed a PS with a narrow peak between 8 and 15 Hz and its higher harmonics, suggesting some organization and regularity. In the following 40 seconds, the arrhythmia accelerated slightly, maintaining an organized spectrum. Afterwards, the PS became slow and irregular, losing its initial characteristics after 60 seconds. Conversely, VF on CPB maintained its organized PS, over a prolonged period. Previous administration of 0.32, 0.64 mg kg-1 of nifedipine maintained the initial characteristics of the PS for 90 and 150 seconds. Similar results were obtained with previous autonomic blockade. In another group of dogs, defibrillation was performed after successive periods of VF, to study electromechanical dissociation (EMD). In all control dogs, EMD was observed after 90 seconds of VF. Pretreatment with nifedipine postponed EMD until 120-150 seconds and was not observed in dogs on CPB. The PS time course during VF seems a reliable method of analyzing and quantifying the different types of VF. It could be related with the onset of EMD, reflecting the metabolic alterations that happen during VF. Nifedipine could delay the ischaemic effects during VF and increase the possibility of successful cardiac resuscitation.
We reviewed 72 patients with penetrating trauma to the extremities who underwent arteriography for proximity injury only. None of the patients had clinical evidence of vascular trauma. There were 62 males and ten females, with a mean age of 29.9 years. Gunshot wounds were the most common cause of injury (91.7%) and the thigh was the most common site of injury (47.2%). A normal arteriogram was found in 55 of 72 patients (76.4%). The remaining 17 patients (23.6%) had arteriographic abnormalities that did not warrant surgery. Only one patient was explored (1.4%) for spasm of the popliteal artery. No vascular injury was found at surgery. This study suggests that routine arteriography in proximity injury only may be unnecessary and that these patients could safely be admitted to the hospital for a 24-hour period of observation.
Desensitization of lung beta-adrenoreceptors induced by 4 day in vivo isoprenaline administration to rats has been investigated both from a functional a biochemical viewpoint. Chronic isoprenaline treatment significantly reduced the relaxing activity of the beta-agonist when tested ex vivo in lung parenchymal strips and also impaired the adenylate-cyclase system. Moreover, the desensitization procedure decreased by about 30% beta-adrenoreceptor number. In vivo indomethacin treatment prevented the loss of pharmacological responsiveness of the tissue to isoprenaline and restored basal adenylate-cyclase activity. These data indicate that in vivo isoprenaline administration actually leads to pulmonary beta-adrenoreceptor desensitization. The involvement of arachidonic acid metabolites in this phenomenon is also discussed.
We compared the development of antigen-induced airway hyperresponsiveness (AHR) 24 h after challenge with Ascaris suum antigen in allergic sheep with acute (n = 7) and with dual (n = 7) airway responses and then attempted to modify this AHR. Cholinergic airway responsiveness was determined by measuring the carbachol dose required to increase specific lung resistance (sRL) 150% (i.e., PC150). Subsequently the sheep were challenged with antigen and sRL was measured at predetermined times to document the presence or absence of a late response. PC150 was redetermined 24 h later followed by bronchoalveolar lavage (BAL) to assess inflammation. Only dual responders developed AHR (PC150 decreased, P less than 0.05). There were no significant differences in BAL between the two groups. Six dual responders were then, on separate occasions (greater than or equal to 3 wk), pretreated with placebo, indomethacin (2 mg/kg iv), or a leukotriene antagonist, FPL-57231 (30 mg inhaled). Neither agent significantly affected the acute response to antigen. Only FPL pretreatment blocked the late response, but both agents blocked the antigen-induced AHR 24 h later. BAL at 24 h showed no significant differences. These results indicate that only dual responders develop AHR 24 h after antigen challenge. This AHR appears independent of the late increase in sRL or the severity of pulmonary inflammation. AHR appears to be sensitive to agents that interfere with the early release or actions of cyclooxygenase and lipoxygenase metabolites in dual responders.
We have investigated the sodium-lithium countertransport system as a screening test for hypertensive disease in children and adolescents using the method of Canessa et al. [New Engl. J. Med. 302: 772-776, 1980]. The sodium-lithium countertransport in erythrocytes was measured in patients, ages 4-18 years, having essential hypertension or secondary hypertension and compared with age-, weight-, sex- and race-matched normotensive controls. Children and adolescents with essential hypertension possessed a significantly higher erythrocyte sodium-lithium countertransport rate than the normotensive control group (0.39 +/- 0.18, n = 28, vs. 0.22 +/- 0.14 mmol Li/l red cells/h, n = 20, respectively; p less than 0.001). Children with secondary hypertension had intermediate values (0.31 +/- 0.15 mmol Li/l red cells/h; n = 17) which did not differ significantly from values of subjects with essential hypertension or normotensive controls. There was no correlation of counter-transport values with age, sex, or body weight in either hypertensive or normotensive groups. However, white normotensive children had significantly higher countertransport levels compared with black normotensives (0.32 +/- 0.14, n = 10, vs. 0.13 +/- 0.07 mmol Li/l red cells/h, n = 10, respectively; p less than 0.005). Similarly, white children and adolescents with essential hypertension had higher mean countertransport measurements than did black hypertensives (0.42 +/- 0.20, n = 21, vs. 0.27 +/- 0.05 mmol Li/l red cells/h, n = 7, respectively) although this difference did not reach statistical significance (p less than 0.1). Although children and adolescents with essential hypertension had a significant elevation of sodium-lithium countertransport when compared to normotensives, the large degree of overlap of countertransport values in these two groups, as well as the intermediate values of children with secondary hypertension, limits the usefulness of the sodium-lithium countertransport as a screening test for essential hypertension in this population. Taking into account the influence of racial differences on the countertransport assay does not sufficiently improve the discriminatory value of the test to render it clinically useful.
The effect of early postnatal malnutrition on the responsiveness of the rat prefrontal cortex was studied by determining excitability thresholds and fatigability to direct cortical stimulation. Malnutrition imposed during the period of rapid brain growth caused a significant increase of cortical chronaxie values as well as increased fatigability of direct cortical responses, indicating a detrimental effect on the axodendritic synapses. Since the prefrontal cortex plays an important role in the temporal organization of behavior, a dysfunction of this cortical area could be a causal link between nutritional and behavioral deficits.
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Bromelain, a proteolytic enzyme extracted from pineapple plants, was investigated for its capacity to interfere with arachidonic acid metabolism, since prostaglandins and other eicosanoids are well-known to be involved in the pathogenesis of inflammatory diseases. Bromelain was tested for its ability to interfere with eicosanoids generation in vivo in two experimentally-induced inflammatory reactions in the rat. Also antiplatelet aggregation activity of bromelain was studied in ex vivo rat platelets. The results seem to indicate an interference of bromelain with arachidonic acid cascade, which, however, deserves further investigation to be better assessed.
The somatosensory cortex responses and periaqueductal grey matter responses evoked by electric peripheral nerve stimulation were studied following topical application of 1% morphine solution to the primary somatosensory area of rat cerebral cortex. Cortically applied morphine increased the negative component of cortical potentials and enhanced the peak-to-peak amplitude of the periaqueductal grey responses. It is suggested that cortical excitation induced by morphine generates descending bioelectrical impulses modulating neuronal activity at this mesencephalic level.
The action of d-amphetamine on the histochemical activities of succinic and malic dehydrogenases in sections of cerebral cortex, cerebellum, and neostriatum has been studied. Meldola blue was used as an exogenous electron carrier in the histochemical reactions. The results have demonstrated that d-amphetamine increases the activity of the enzymes studied.
The possible involvement of arachidonic acid (AA) or its metabolites in beta-adrenoceptor desensitization has been studied in rat lung parenchyma both from a functional and a biochemical point of view. In vitro perfusion of rat lungs with AA (3 X 10(-5)M for 20 min) reduced the relaxant effect of isoproterenol (ISO) on lung parenchymal strips, shown by a shift to the right of ISO dose-response curve, similar to that obtained using desensitizing concentration of specific beta-agonist. Moreover, AA treatment reduced the capacity of ISO to stimulate adenylate-cyclase activity, whereas the number of beta-receptor binding sites was not significantly modified. Inhibition of cyclo-oxygenase pathway by indomethacin (INDO) (1.5 X 10(-5)M) prevented both the loss of ISO-relaxing capacity and the decrease of adenylate-cyclase activity induced by AA treatment. In order to support the role of eicosanoids in beta-adrenoceptor desensitization, changes of endogenous free AA levels have also been studied in lung homogenates. Perfusion of rat lung with ISO (10(-6)M for 20 min) decreased by about 50% the levels of free AA and the pretreatment with BW755C (9 X 10(-5)M), a lipo- and cyclo-oxygenase inhibitor, prevented this phenomenon. On the basis of these results, we suggest that the activation of AA cascade is actually involved in beta-adrenoceptor desensitization in lung tissues with a possible interference at the site beyond the drug-receptor interaction.