Biomedical subjects
Publications and source records attributed to M Leon.
The authors tried to evaluate the benefit of sympathetic nerve blocks with guanethidine in 32 patients with a sympathetic dystrophy syndrome who failed to respond to conventional treatment.
The emphasis on the effects of early olfactory restriction has been on the deleterious nature of the consequences of this abnormal early experience. While these effects are certainly present and dramatic, it is also the case that the olfactory system is left fairly intact by this experimental manipulation. If one asks what mechanisms may account for the preservation of the developing olfactory system in the face of diminished activity, there are a number of neural responses that could help the system compensate for the damage inflicted upon the system by the loss of early sensory stimulation. I describe what may be compensatory responses to the decrease in dopamine, the increase in norepinephrine, the structural changes induced in the glomeruli and the increase in cell death within the olfactory bulb that follow neonatal unilateral naris occlusion.
In order to determine whether molecular features of odorants are represented spatially in the glomerular layer of the olfactory bulb, we used metabolic mapping of [14C] 2-deoxyglucose uptake in rats exposed to equal vapor concentrations of odorants differing systematically in chemical structure. The odorants were ethyl acetate, ethyl butyrate, isoamyl acetate, and isoamyl butyrate. Statistical analysis of anatomically standardized arrays of uptake revealed that each ester produced a characteristic spatial pattern of activity in the glomerular layer. The patterns were similar in different rats exposed to the same odorant, and their complexity increased with increasing odorant carbon number. This finding suggests that the presence of more potentially recognized molecular features is associated with a greater number of activated receptors. Individual regions of the glomerular layer responded specifically to isoamyl esters, and other regions preferred ethyl esters. Regions of similar specificity occurred in lateral and medial aspects of the bulb, the medial representation being more caudal and ventral than the lateral one. This pattern correlates with projections of olfactory sensory neurons expressing the same putative olfactory receptor gene. The patterns overlapped greatly in the posterolateral and posteromedial glomerular layer, a finding one should predict, given the large overlap in chemical structure across the aliphatic esters. Thus, molecular features appear to be encoded spatially in the glomerular layer, and the identity of the odorant may be determined by a subsequent decoding of the combination of molecular features represented in the glomerular layer.
This study compares the immediate and long-term outcomes of a primary coronary stenting strategy with primary balloon angioplasty with stent bailout in the treatment of patients with acute myocardial infarction (AMI). One hundred forty-seven consecutive patients who underwent primary balloon angioplasty with stent bailout (n = 94) or primary stenting (n = 53) for AMI were clinically followed for 8.1 +/- 5.7 and 8.5 +/- 4.5 months, respectively. Immediate results, as well as in-hospital and long-term ischemic events (death, reinfarction, and repeat revascularization) were compared between both groups. Angiographic success was 91.5% in the balloon angioplasty group and 94% in the stent group. In-hospital and late follow-up combined ischemic events were 22 of 94 (23%) versus 0 of 53 (0%); p < 0.001 and 33 of 78 (42%) versus 13 of 53 (25%), p = 0.04 for the balloon angioplasty and stent groups, respectively. At 6 months, the cumulative probability of repeat target lesion revascularization was higher in the balloon angioplasty group (47% vs 18%, p = 0.0006) as was the probability of late target revascularization (36% vs 18%, p = 0.046); the cumulative event-free survival after 6 months was significantly lower in the balloon angioplasty group (44% vs 80%, p = 0.0001). This study demonstrates that a primary stent placement strategy in patients with AMI is safe, feasible, and superior to primary balloon angioplasty with stent bailout. Primary stenting results in a larger postprocedural minimal luminal diameter, a lower early and late recurrent ischemic event rate, and a lower incidence of target lesion revascularization at follow-up.
Our purpose was to review the current status of carotid artery stent placement throughout the world. Surveys were sent to major interventional centers in Europe, North and South America, and Asia. Information from peer-reviewed journals was also included and supplemented the survey. The survey asked various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. Of the centers which were sent surveys, 24 responded. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 2,048 cases, with a technical success of 98.6%. Complications that occurred during carotid stent placement or within a 30-day period following placement were recorded. Overall, there were 63 minor strokes, with a rate of occurrence of 3.08%. The total number of major strokes was 27, for a rate of 1.32%. There were 28 deaths within a 30-day postprocedure period, resulting in a mortality rate of 1.37%. Restenosis rates of carotid stenting have been 4.80% at 6 mo. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative to vascular surgery, especially for patients that are at high risk for standard carotid endarterectomy. The periprocedural risks for major and minor strokes and death are generally acceptable at this early stage of development.
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Neural networks have demonstrated their research potential in bio-medical sciences. The literature is filled with experiments that evidence the value of neural networks for the solution of diagnostic and predictive problems. The next step is to direct research efforts toward implementation of these neural networks into the clinical information environments where their diagnostic and predictive capabilities can be truly utilized. To accomplish this goal, it is necessary to create a new generation of neural network tools that ease the transition of experimental results to a production state. This paper describes the architecture of such a system.
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Early olfactory preference training causes both an increased number of juxtaglomerular cells and an increased number of such cells expressing Fos protein. In contrast, there are fewer cells expressing Fos protein in the granule cell layer after training. Here, we report no change in the number or size of granule and mitral cells as a consequence of these early olfactory experiences.
OBJECTIVE: To quantify the functional venous outflow obstruction with different location and extent of obstruction attributed to previous deep vein thrombosis. DESIGN: Case-control study. SETTING: Vascular Laboratory, St Mary's Hospital Medical School, London, England. PATIENTS: Two groups: group 1, 25 case patients and 9 control subjects, and group 2, 45 case patients and 30 control subjects. INTERVENTIONS: Ascending venography, duplex scanning, air plethysmography, and venous pressure measurements in the foot and the arm via a 21-gauge butterfly needle. MAIN OUTCOME MEASURES: Venous outflow fraction (VOF), venous outflow resistance (VOR), and arm-foot pressure differential (A-F PD) at rest and after reactive hyperemia. RESULTS: Venous outflow resistance was evaluated in group 1. Twenty-two case patients underwent VOF testing, and 16 had A-F PD measurement performed. Case patients in group 2 underwent VOF testing. Signs and symptoms of chronic venous dysfunction were associated with the anatomical extent of obstruction. Limb swelling and ache were present in most of the patients; skin changes were noted in about 30% and ulceration in 10% of patients. The results of all tests showed no evidence of obstruction in control subjects. In most case patients with popliteal vein obstruction, test results were similar to those in control subjects: the more proximal the veins involved, the more severe the obstruction. In 16 case patients, all 3 tests were performed and agreement between A-F PD and VOR test results was found in 14 of them. The VOF test results agreed with the results of A-F PD and VOR tests in 9 case patients. In group 2, 50% of the limbs with obstruction proximal to the popliteal vein had a reduced VOF, which became worst in the limbs with extensive obstruction, particularly when the iliac veins were involved. Of the 73 limbs tested for VOF in both groups, only 7 limbs (9.6%) had their venous outflow markedly reduced by occlusion of the superficial veins. CONCLUSIONS: The anatomical extent of venous obstruction and the development of collateral circulation determine the hemodynamic severity of the chronic venous obstruction. The deep collaterals seem to be more important than the superficial venous system in bypassing the obstruction. The VOR and the A-F PD tests can be used to identify those patients who have venous obstruction, whereas the use of the VOF test may reduce the need for performing the above tests in 50% of the patients.
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It has been demonstrated that patients predisposed to the development of varicose veins have an abnormal venous tone, and may have symptoms in the absence of obvious varicosities. It has been suggested that venotonic drugs relieve the symptoms of chronic venous insufficiency by decreasing capillary leakage and improving venous tone. The aim of this study was to determine the effect of Daflon 500 mg in patients with abnormal venous elasticity without varicose veins. Twenty-five healthy female volunteers aged 18-35 were included in the study. They presented with symptomatic varicose veins in one leg and an abnormal elastic modulus without varicosities in the opposite leg. Treatment group: 12 patients received 2 tablets of Daflon 500 mg (1000 mg/day); control group: 13 patients received no treatment. The elastic modulus K was determined using the air plethysmograph. Simultaneous measurements of calf volume changes were made in response to different venous pressures produced by a thigh pneumatic cuff. In the control group K (mean +/- sd) was 10.8 x 10(3) +/- 4.1 x 10(3) N/m2 at the beginning and 10.2 x 10(3) +/- 3.1 x 10(3) N/m2 at the end of the study (P > 0.1). In the treatment group the initial K was 10.2 x 10(3) +/- 3.9 x 10(3) N/m2 and 14.2 x 10(3) +/- 5.1 x 10(3) N/m2 at the end (P < 0.02). The results of the Wilcoxon rank sum test indicated that 4 weeks' therapy with Daflon 500 mg is effective in improving venous tone in patients with symptoms but without varicose veins.
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Previous work has shown that odors induce focal uptake of [14C]2-deoxyglucose (2-DG) within the glomerular layer of the main olfactory bulb and that the amount of 2-DG accumulated in these foci increases after early odor learning. To determine if learning-associated changes in 2-DG uptake occur across the entire glomerular layer, we have mapped uptake throughout the layer at fixed angles in coronal sections through the bulb. Resulting arrays for individual bulbs were corrected for differing bulb size and averaged across experimental groups to address the spatial distribution of uptake. The average arrays revealed at least three discrete fields of uptake in naive, peppermint-exposed rats at postnatal day 19 that were not seen in air-exposed littermates. In agreement with previous studies, early preference training with peppermint odor given on postnatal days 1-18 increased 2-DG uptake at postnatal day 19 within odor-dependent patches of uptake in the posterior half of the midlateral bulb, whereas odor-dependent, ventrolateral patches of uptake did not increase to the same extent. In addition, early preference learning was associated with significantly increased 2-DG uptake average over the entire analyzed glomerular layer. These increases were smaller than those within odor-dependent foci and were distributed widely across the glomerular layer, showing low overlap between trained and control rats in anterior regions where peppermint odor did not stimulate 2-DG uptake. The widely distributed increases in 2-DG uptake after learning may reflect changed activity of centrifugal projections that diffusely innervate the glomerular layer.
Olfactory stimulation evokes a column of activity within the olfactory bulb extending from the glomerular layer to the granule cell layer that can be visualized with 2-deoxyglucose autoradiography, optical imaging, Fos protein immunohistochemistry and c-fos mRNA in situ hybridization. The Fos response to odors is typified by the activity of relatively few juxtaglomerular cells, which often occur in foci, and a large number of granule cells extending through much of the bulb. In this study, we characterized the granule cell response to an odor for which young rats had acquired a preference. Fos-like immunoreactive granule cells were quantified by image analysis, and densely stained cells were counted in a region previously shown to be responsive to peppermint odor. We found that odor-trained pups have about half the number of Fos-immunopositive superficial granule cells which respond to a learned odor than do control pups. We then determined whether there was a correlation between the juxtaglomerular cell response and the response of the superficial granule cells deep to those glomerular layer cells. We found a positive correlation between the number of juxtaglomerular cells and the number of granule cells demonstrating Fos immunoreactivity in both control and trained pups, a relationship that changed with early olfactory training.
Synaptophysin is a synaptic vesicle protein that provides a marker of synaptic distribution in the brain. We used synaptophysin immunohistochemistry to detect changes in synaptic distribution in the main olfactory bulb during normal early postnatal development and following early olfactory restriction. Synaptophysin-like immunoreactivity appears early in the postnatal development of most bulbar laminae. In the first postnatal week, the entire glomerular neuropil is stained intensely, but by PND 19, the glomerular perimeter becomes more intensely stained than its core. This immunoreactivity is especially dense along that aspect of the perimeter facing the olfactory nerve layer. To determine if this developmental pattern could be affected by early olfactory experience, unilateral naris closure was performed on PND 1. In deprived bulbs at PND 19, the difference in staining between the glomerular border and the glomerular core is significantly less than in either contralateral glomeruli or glomeruli from unoperated animals. The difference between the glomerular border and the glomerular core is greater in bulbs contralateral to a closed naris than in bulbs from unoperated animals. Staining intensity measured over entire glomeruli is not altered by naris closure, nor is staining of other laminae. The changes detected after naris closure indicate that the glomerular distribution of synaptophysin may be particularly sensitive to early olfactory experience.
OBJECTIVE: To determine the lower-limb venous hemodynamics in patients with varying grades of chronic venous insufficiency (CVI), not due to deep vein thrombosis, when matched for age and duration of disease. DESIGN: Case-control study. SETTING: Normal volunteers and patients with different grades of CVI referred to the vascular unit of a university hospital. MATERIALS: Fifty-one legs (40 patients) with CVI, but without a history of deep vein thrombosis, and 24 normal legs (20 volunteer subjects). These selected legs were grouped according to the severity of CVI (classes 0 - through 3) so that each class was matched for age (all study participants <60 years) and duration of signs and symptoms (<10 years). INVESTIGATIONS: Air plethysmography and color flow duplex imaging. MAIN OUTCOME MEASURES: Venous volume, venous filling index, and outflow, ejection, and residual volume fractions were assessed in all limbs with air plethysmography. The presence of reflux was confirmed by the results of color flow duplex imaging. RESULTS: Ten (42%) of 24 limbs in class 0 had no reflux. Twenty-five (57%) of the 44 limbs in classes 0 and 1 had superficial reflux alone, while all the limbs in class 1 had some degree of reflux in the superficial veins. The sites of reflux in these limbs were similar. The patterns of reflux in classes 2 and 3 were more complex. Eight (26%) of the 31 limbs had superficial reflux alone, whereas 10 (32%) had all three systems involved (superficial, deep, and perforating). The venous volume, venous filling index, and residual volume fraction worsened with progression of CVI. Significant statistical differences could, however, only be demonstrated between classes 0 and 1 vs classes 2 and 3. No changes could be found in the ejection and outflow fractions. CONCLUSIONS: Patients (age <60 years) with CVI of less than 10 years' duration and with no history of deep vein thrombosis had venous hemodynamic changes that correlated well with the clinical severity of the disease. This was owing to the increased reflux, as the ejecting ability of the calf muscle pump remained intact, and the venous outflow was normal.