Continuous rise in oxygen consumption during prolonged military loaded march in the heat with and without fluid replacement: a pilot study.

INTRODUCTION: V̇O2 drift, the rise in oxygen consumption during continuous exercise, has not been adequately reported during prolonged military marches. The purpose of this study was to analyse V̇O2 and energy expenditure (EE) during a loaded march with and without rehydration efforts. Second, the study aimed to compare EE throughout the march with predicted values using a validated model. METHODS: Seven healthy men (23±2 years; V̇O2max: 50.8±5.3 mL/kg/min) completed four 60 min loaded marches (20.4 kg at 50% V̇O2max) in a warm environment (30°C and 50% relative humidity). Three were preceded by hypohydration via a 4-hour cold water immersion (18°C). The control (CON) visit was a non-immersed euhydrated march. After water immersion, subjects were rehydrated with 0% (NO), 50% (HALF) or 100% (FULL) of total body mass lost. During exercise, V̇O2 and EE were collected and core temperature change was calculated. To determine if EE could be accurately predicted, values were compared with a calculated estimate using the US Army Load Carry Decision Aid (LCDA). RESULTS: At the start of exercise, there was no difference between conditions in V̇O2 (ALL: 24.3±0.3 mL/kg/min; p=0.50) or EE (ALL: 8.6±1.0 W/kg; p=0.68). V̇O2 (p=0.02) and EE (p<0.01) increased during exercise and were 12.3±10.0% and 12.8±9.5% greater, respectively, at 60 min across all trials and were not mitigated by rehydration amount. There was an effect of core temperature change on V̇O2 for each condition (CON: r=0.62; NO: r=0.47; HALF: r=0.70; FULL: r=0.55). LCDA-predicted values were different from measured EE during exercise. CONCLUSION: V̇O2 drift occurred during loaded military marches and was associated with increases in EE and core temperature change. Pre-exercise hypohydration with water immersion followed by rehydration did not influence the degree of drift. LCDA prediction of EE may not agree with measured values during prolonged loaded marches where V̇O2 drift occurs.

[Evolution of the interventional reperfusion strategy and reperfusion times in acute ST-segment elevation myocardial infarction]. / Évolution de la prise en charge interventionnelle et des délais de reperfusion à la phase aiguë de l'infarctus du myocarde avec sus-décalage du segment ST.

BACKGROUND: In patients with acute ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI), the recommended times (first medical contact-to-balloon (M2B) <120 or <90min, and door-to-balloon (D2B) <45min) are reached in less than 50% of patients. PURPOSE: To compare the interventional reperfusion strategy and reperfusion times between two series of consecutive STEMI patients referred for pPCI within 12hours of symptom onset, in 2007 and 2012. METHODS: Retrospective study of 182 patients, 87 admitted from January 2007 to March 2008 (period 1), and 95 admitted from January to December 2012 (period 2). The procedural characteristics and the different times between onset of pain and mechanical reperfusion were gathered and compared by non-parametric tests. RESULTS: Radial access, thromboaspiration, and drug eluting stents were more frequent, and cardiogenic shock was less common during period 2, compared with the period 1. The median time from first medical contact to balloon (M2B) decreased by 26% (135min, [quartiles: 113-183] in 2007 versus 100 [76-137] in 2012, P<0.001), in relation to the reduction in both prehospital times and time in the catheterization laboratory (D2B: 51 [44-65] and 44min [37-55], respectively, P<0.01). CONCLUSIONS: The D2B and M2B times significantly decreased in our centre between 2007 and 2012, and reached the recommended values in >60% of the cases. This may be explained by better coordination between emergency medical units and interventional cardiologists, and by the presence of two paramedics in the catheterization laboratory for 24/24 7/7 pPCI since 2010 in France, in accordance with recent national regulation.

Neuregulin1 and ErbB expression in the uninjured and regenerating olfactory mucosa.

Neuregulin1, a protein involved in signaling through the ErbB receptors, is required for the proper development of multiple organ systems. A complete understanding of the expression profile of Neuregulin1 is complicated by the presence of multiple isoform variants that result from extensive alternative splicing. Remarkably, these numerous protein products display a wide range of divergent functional roles, making the characterization of tissue-specific isoforms critical to understanding signaling. Recent evidence suggests an important role for Neuregulin1 signaling during olfactory epithelium development and regeneration. In order to understand the physiological consequences of this signaling, we sought to identify the isoform-specific and cell type-specific expression pattern of Neuregulin1 in the adult olfactory mucosa using a combination of RT-qPCR, FACS, and immunohistochemistry. To complement this information, we also analyzed the cell-type specific expression patterns of the ErbB receptors using immunohistochemistry. We found that multiple Neuregulin1 isoforms, containing predominantly the Type I and Type III N-termini, are expressed in the uninjured olfactory mucosa. Specifically, we found that Type III Neuregulin1 is highly expressed in mature olfactory sensory neurons and Type I Neuregulin1 is highly expressed in duct gland cells. Surprisingly, the divergent localization of these Neuregulin isoforms and their corresponding ErbB receptors does not support a role for active signaling during normal turnover and maintenance of the olfactory mucosa. Conversely, we found that injury to the olfactory epithelium specifically upregulates the Neuregulin1 Type I isoform bringing the expression pattern adjacent to cells expressing both ErbB2 and ErbB3 which is compatible with active signaling, supporting a functional role for Neuregulin1 specifically during regeneration.

[Evaluation of a selective strategy for glycoprotein IIb/IIIa inhibitors administration in non-ST segment elevation acute coronary syndromes]. / Évaluation d'une stratégie sélective de prescription des antagonistes de la glycoprotéine IIb/IIIa dans les syndromes coronariens aigus sans sus-décalage du segment ST.

AIMS: We evaluated the impact of a selective strategy for glycoprotein IIb/IIIa inhibitors administration in non ST-segment elevation acute coronary syndrome. PATIENTS AND METHOD: Between February 1st, 2007, and February 1st, 2009, 331 consecutive patients were prospectively included in the study. Criteria for upstream glycoprotein IIb/IIIa inhibitors administration were as follows: transient ST elevation greater than 1mm, ST-segment depression greater than 2mm, ischemic recurrence, TIMI risk score greater than 5. Global mortality and cardiovascular outcomes were assessed at Day 7 and Day 30. RESULTS: The overall use of glycoprotein IIb/IIIa inhibitors was 16%. The procedure was successfully applied in 98%. Compared with non eligible patients (group 1, n = 254), eligible patients (group 2, n = 77) had a higher risk profile, median age: 73 versus 66, p < 0.01, TIMI risk score: 4 versus 3, p < 0.001. Eligible patients (66%) actually received the treatment. Among the 26 eligible but untreated patients, 19% had major bleeding risk, 34% had an unfavourable risk-benefit ratio and 34% were not suitable for an invasive strategy. Cardiovascular events occurred in 5.1% at Day 7 (Group 1, 1.6%), and 6.0% at Day 30 (group 1, 2.4%). Overall mortality at Day 30 was 1.2% (0.4% in Group 1). CONCLUSION: A strategy for glycoprotein IIb/IIIa inhibitors administration in non ST-segment elevation acute coronary syndrome restricted to 4 very high risk situations may be considered, without evidence for a loss of chance in intermediate risk patients, untreated although eligible for treatment according to the current guidelines.

[Secondary prevention after acute coronary syndrome: therapeutic goals achievement in relation with changes in guidelines]. / Prévention secondaire après syndrome coronarien aigu: évolution des recommandations et niveaux d'atteinte des objectifs.

BACKGROUND: Secondary prevention is a key strategy for reducing levels of coronary heart disease, but a gap between guidelines and practice remains. OBJECTIVES: The aim of this double-part survey was to evaluate the improvement in secondary prevention one year after acute coronary syndrome (ACS) in real life, between 1999 and 2005, with respect to the change in guidelines. METHODS: Two surveys of almost similar design were performed in 1999 and 2005-2006. In each survey, unselected consecutive patients suffering from ACS (n=112 hospitalized in 1998, and n=110 in 2004) were evaluated at admission, and one year after hospitalization, for the risk factors, lifestyle, and achievement of therapeutic goals recommended by the most recent guidelines. Follow-up (FU) data were obtained by mail and phone contact with patient, general practitioner and cardiologist, and medical laboratory when appropriate. RESULTS: At 1-year FU (n=192 survivors with FU), smoking cessation (87% in 1999 versus 89% in 2005) and obesity (13% versus 19%, respectively) did not vary significantly. Blood pressure was controlled (< 140/90 mmHg, excepted in diabetics in 2005 with less than 130/80 mmHg) in 65% versus 80% (p<0.03). The rate of patients with no or controlled diabetes mellitus decreased from 1999 to 2005 (90% versus 76%), despite more intensive treatment (insulin in 1% versus 20%).The goals for LDL cholesterol were achieved in 47% of patients in 1999 (< 3.4 mmol/L) and in 76% in 2005 (< 2.6 mmol/L) (p<0.0001). Goals for triglycerides were achieved in 86% in 1999 (< 2g/L), and in 80% in 2005 (< 1.5 g/L) (NS). Besides, 63% of patients received an hypolipemic drug in 1999 (a statin in 59%) and 91% in 2005 (a statin in 88%). Mean number of controlled risk factors was 3.96+/-1.52 in 1999 versus 4.94+/-1.83 in 2005, and prevalence of pts with more than five controlled risk factors at one year FU increased from 15 to 44% (p<0.0001). CONCLUSIONS: These results, drawn from unselected consecutive patients managed in real life, demonstrate an improvement in secondary prevention one year after ACS, between 1999 and 2005, despite strengthened guidelines for blood pressure, triglycerides and LDL cholesterol levels. Control of obesity and diabetes remains unoptimal.

Intranasal inoculation with the olfactory bulb line variant of mouse hepatitis virus causes extensive destruction of the olfactory bulb and accelerated turnover of neurons in the olfactory epithelium of mice.

Viral upper respiratory infections are the most common cause of clinical olfactory dysfunction, but the pathogenesis of dysosmia after viral infection is poorly understood. Biopsies of the olfactory mucosa in patients that complain of dysosmia after viral infection fall into two categories: one in which no olfactory epithelium is seen and another in which the epithelium is disordered and populated mainly by immature neurons. We have used intranasal inoculation with an olfactory bulb line variant of MHV to study the consequences of viral infection on peripheral olfactory structures. MHV OBLV has little direct effect on the olfactory epithelium, but causes extensive spongiotic degeneration and destruction of mitral cells and interneurons in the olfactory bulb such that the axonal projection from the bulb via the lateral olfactory tract is markedly reduced. Moreover, surviving mitral cells apparently remain disconnected from the sensory neuron input to the glomerular layer, judging from retrograde labeling studies using Dil. The damage to the bulb indirectly causes a persistent, long-term increase in the turnover of sensory neurons in the epithelium, i.e. the relative proportion of immature to mature sensory neurons and the rate of basal cell proliferation both increase. The changes that develop after inoculation with MHV OBLV closely resemble the disordering of the olfactory epithelium in some patient biopsies. Thus, damage to the olfactory nerve or bulb may contribute to a form of post-viral olfactory dysfunction and MHV OBLV is a useful model for studying the pathogenesis of this form of dysosmia.

Functional consequences following infection of the olfactory system by intranasal infusion of the olfactory bulb line variant (OBLV) of mouse hepatitis strain JHM.

The present study assessed the functional consequences of viral infection with a neurotropic coronavirus, designated MHV OBLV, that specifically targets central olfactory structures. Using standard operant techniques and a 'go, no-go' successive discrimination paradigm, six BALB/c mice were trained to discriminate between the presentation of an air or odor stimulus (three mice for each of the odorants propanol and propyl acetate). Two additional BALB/c mice were trained to discriminate between the presentation of air and the presentation of either vanillin or propionic acid. Following criterion performance, each mouse received an additional 2000 trials of overtraining. At completion of overtraining one mouse from the propanol and propyl acetate groups were allocated as untreated. The remaining six mice were inoculated with 300 microl of the OBLV stock per nostril for a total of 1.5 x 10(6) p.f.u. in 600 microl. Following a 1 month rest, untreated and inoculated animals were again tested on their respective air versus odor discrimination task. Untreated animals immediately performed at criterion levels. In contrast, inoculated animals varied in their capacity to discriminate between air and odorant. Five of the six inoculated mice showed massive disruption of the olfactory bulb, including death of mitral cells; the other was more modestly affected. In addition, the density of innervation of the olfactory mucosa by substance P-containing trigeminal fibers is also affected by inoculation. Those mice that remained anosmic to the training odorants had the most severe reduction in mitral cell number and substance P fiber density among the inoculated animals.

Plasma dynamics in capillary discharge soft x-ray lasers.

The dynamics and stability of collapsing gas columns, generated by a fast capillary discharge setup, are studied for obtaining soft x-ray amplification in highly ionized ions. Electron temperature and density measurements at the peak of the compression stage are used for tuning the discharge parameters. Once the needed conditions were achieved, strong amplification of the 3s-3p transition in Ne-like Ar ions at 469 A is observed. A gain coefficient of >0.75 cm(-1) and a beam divergence of <5 mrad are measured along plasma columns of <150 microm diameter and up to 165 mm length.

Mouse cyp2g1 gene: promoter structure and tissue-specific expression of a cyp2g1-lacz fusion gene in transgenic mice.

The structure of the mouse Cyp2g1 gene was determined to identify regulatory regions important for its olfactory mucosa-specific expression. Two Cyp2g1 genomic clones were isolated and characterized. A 3.6-kilobase 5'-flanking sequence was used to prepare a Cyp2g1--LacZ fusion gene for transgenic mice production. Transgene expression, as determined by beta-galactosidase activity in tissue extracts, was detected in the olfactory mucosa, but not in any other tissues examined, in five different transgenic lines. Thus, the 3.6-kilobase fragment contained regulatory elements sufficient for olfactory mucosa-specific and proper developmental expression of the reporter gene. However, histological and immunohistochemical studies indicated that the expression of the transgene in the olfactory mucosa was patchy and the cellular expression patterns of the transgene did not exactly match that of the endogenous gene. These results implicate the presence of additional regulatory sequences that are necessary for the correct cell type-selectivity within the olfactory mucosa.

Rhinotopy is disrupted during the re-innervation of the olfactory bulb that follows transection of the olfactory nerve.

Re-innervation of the olfactory bulb was investigated after transection of the olfactory nerve using monoclonal antibody RB-8 to assess whether rhinotopy of the primary olfactory projection is restored. In normal animals RB-8 heavily stains the axons, and their terminals, that project from the ventrolateral olfactory epithelium onto glomeruli of the ventrolateral bulb (termed RB-8(+)). In contrast, axons from dorsomedial epithelium are unlabeled (RB-8(-)) and normally terminate in the dorsomedial bulb. Sprague-Dawley rats underwent unilateral olfactory nerve transection and survived for 6 weeks prior to perfusion, sectioning and immunostaining with RB-8. Nerve lesion does not shift the position of the boundary between RB-8(+) and RB-8(-) regions of the epithelium. However, following transection and bulb re-innervation, the distribution of RB-8(+) and RB-8(-) axons is markedly abnormal. First, in all 10 experimental animals RB-8(-) axons displace RB-8(+) axons from anterior glomeruli. Furthermore, the usual target of the RB-8(-) fibers, i.e. the dorsomedial bulb at more posterior levels of the bulb, remains denervated, judging by the lack of staining with antibodies that label axons derived from all epithelial zones. Finally, RB-8(+) fibers invade foreign territory in the dorsolateral bulb on the lesioned side in some cases. The shifts in terminal territory in the bulb after transection contrast with the restoration of the normal zonal patterning of the projection after recovery from methyl bromide lesion, but is consistent with reports of mistargeting by a receptor-defined subset of neurons after transection.

Anterior distribution of human olfactory epithelium.

OBJECTIVES/HYPOTHESIS: To functionally investigate the distribution of the olfactory epithelium in humans by means of the electro-olfactogram (EOG) and anatomically located biopsy specimens. STUDY DESIGN: Prospective, nonrandomized, investigational. METHODS: Supra-threshold EOG recordings were made on 12 healthy, trained volunteers (6 women, 6 men; age range, 21-48 y). Vanillin was used as the stimulus, since it exclusively excites olfactory receptor neurons. The EOG was recorded with tubular electrodes that were placed using thin-fiber endoscopic guidance. Biopsy specimens were obtained of anterosuperior nasal cavity mucosa in the same regions as the positive EOGs in 15 smell-tested patients (7 women, 8 men; age range, 22-60 y) during routine nasal and sinus surgery. This biopsied tissue was histologically processed and stained for olfactory and neural proteins. RESULTS: Viable responses to EOG testing were obtained in 7 of 12 subjects. In these seven subjects it was possible to identify nine sites above or below the anterior middle turbinate insertion where EOGs were obtained. The biopsy results showed mature olfactory receptor neurons in this same area. CONCLUSIONS: Human olfactory epithelium appears to be distributed more anteriorly than previously assumed.

Reinnervation of the rat olfactory bulb after methyl bromide-induced lesion: timing and extent of reinnervation.

We used the inhalation of methyl bromide gas to produce a near-complete destruction of the rat olfactory epithelium and analyzed the reinnervation of the bulb during reconstitution of the epithelium. The degeneration of olfactory axons elicits a transient up-regulation of glial cell proliferation and glial fibrillary acidic protein expression in the olfactory nerve and olfactory nerve layer of the bulb. Anterograde transport after intranasal infusion of wheat germ agglutinin conjugated horseradish peroxidase demonstrates that the first nascent axons reach the bulb within the first week after lesion. Subsequently, a massive wave of fibers arrives at the bulb between 1 and 2 weeks postlesion, and enters the glomeruli between 2 and 3 weeks postlesion. However, the olfactory projection does not stabilize until 8 weeks after lesion judging from the return in growth associated protein-43 expression to control levels. The extent of reinnervation after lesion is correlated with the completeness with which the epithelium reconstitutes itself. In rats that are lesioned while fed ad libitum, there is near-complete reconstitution of the neuronal population, and the projection onto the bulb fills the glomerular layer in its entirety. However, in rats that are lesioned while food restricted, a significant fraction of olfactory epithelium becomes respiratory during its reconstitution, and the population of reinnervating fibers is less. As a consequence, the posterior half of the bulb remains hypoinnervated overall and denervated at its caudal margin. The preferential reinnervation of the anterior bulb in the food-restricted, methyl bromide gas-lesioned animals indicates that the mechanisms that guide the growth of the olfactory axons and restore receptotopy do not operate with the same precision in this setting as they do during development or during the lower level of turnover associated with the "normal" laboratory existence. Accordingly, we hypothesize that the persistence of a significant population of pre-existing neurons is needed to preserve receptotopy during reinnervation. In addition, the results suggest that in the face of massive turnover and a reduced afferent population, there is a tendency for reinnervating axons to fill available synaptic space.

Adult olfactory epithelium contains multipotent progenitors that give rise to neurons and non-neural cells.

We have infused replication-incompetent retroviral vectors into the nasal cavity of adult rats 1 day after exposure to the olfactotoxic gas methyl bromide (MeBr) to assess the lineage relationships of cells in the regenerating olfactory epithelium. The vast majority of the retrovirus-labeled clones fall into three broad categories: clones that invariably contain globose basal cells (GBCs) and/or neurons, clones that always include cells in the ducts of Bowman's glands, and clones that are composed of sustentacular cells only. Many of the GBC-related clones contain sustentacular cells and horizontal basal cells as well. Most of the duct-related clones contain gland cells, and some also include sustentacular cells. Thus, the destruction of both neurons and non-neuronal cells that is caused by MeBr activates two distinct types of multipotent cells. The multipotent progenitor that gives rise to neurons and non-neuronal cells is a basal cell, whereas the progenitor that gives rise to duct, gland, and sustentacular cells resides within the ducts, based on the pattern of sparing after lesion and the analysis of early regeneration by using cell type-specific markers. We conclude that the balance between multipotency and selective neuropotency, which is characteristic of globose basal cells in the normal olfactory epithelium, is determined by which cell types have been depleted and need to be replenished rapidly.

Transplantation of multipotent progenitors from the adult olfactory epithelium.

Mammalian olfactory epithelium produces new neurons rapidly throughout adulthood. Here, we demonstrate that precursor cells harvested from the adult olfactory epithelium, when transplanted into the nasal mucosa of host rats exposed previously to an olfactotoxic gas, engraft and participate in neuroepithelial reconstitution. In contrast to their normal neuronal fate in situ, grafted precursors harvested from bulbectomized donors produced non-neuronal cells as well as neurons. These results demonstrate that epithelial precursors activated following olfactory bulbectomy are not irreversibly committed to making neurons. Thus, olfactory progenitors are subject to a form of feedback control in vivo that regulates the types of cells that they produce within a broader-than-neuronal repertoire.

Immunohistochemical identification of discrete subsets of rat olfactory neurons and the glomeruli that they innervate.

Glomeruli at the posterior margin of the main olfactory bulb differ in several respects from those located in the remainder of the bulb; e.g., the olfactory sensory neurons (OSNs) that project here exhibit a distinct biochemical phenotype and signal transduction pathway, the microcircuitry of the glomeruli is substantially altered, and the glomeruli are activated by unconventional odorants. In the present work, we report that the monoclonal antibodies 2C6 and MAb213 label distinct subsets of OSNs in the olfactory epithelium (OE), including their axons to their terminations in the main olfactory bulb (MOB). Neurons immunopositive with 2C6 are concentrated in the cul-de-sacs of ectoturbinates 1 and 2 and of endoturbinate IV. Unlike the vast majority of OSNs, 2C6(+) neurons express olfactory marker protein (OMP) at a low level, but their failure to stain with anti-GAP-43 labeling indicates that the OMP "weak" neurons are nonetheless mature. Glomeruli positive for 2C6 are bilaterally symmetrical and occupy reproducible positions along the posterior margin of the MOB. Three of these are very large, and we refer to them as the lateral, posterior ventral, and anterior ventral 2C6(+) necklace glomeruli. MAb213(+) neurons are concentrated in the posteriormost tips of the cul-de-sacs and recesses at the reflection of the OE at the cribriform plate. Like 2C6(+) neurons, MAb213(+) OSNs are weakly labeled with anti-OMP but are fully mature. MAb213(+) glomeruli are also bilaterally symmetrical; they occupy reproducible positions along the posterior margin of the MOB. The three largest glomeruli occupy lateral, posterior ventral, and posterior positions; the first two are found close to the aforementioned 2C6(+) glomeruli. MAb213 also intensely labels one of the glomeruli of the modified glomerular complex, a string of small glomeruli ventrally, and another string dorsal to the accessory olfactory bulb. Acetylcholinesterase (AChE) histochemical staining of adjacent sections showed that many, but not all, MAb213(+) glomeruli colocalize with dense or moderate AChE staining. Thus, it is likely that the "necklace olfactory glomeruli" (Shinoda et al., 1990, 1993) and the phosphodiesterase (PDE2)(+) glomeruli (Juilfs et al., 1997) are a subset(s) of the MAb213(+) glomeruli. On the other hand, 2C6(+) glomeruli are not associated with AChE staining. These data indicate that the 2C6(+) glomeruli comprise a novel subset in the posterior MOB. In addition to the 2C6(+) and MAb213(+) necklace glomeruli, there is another distinct set of glomeruli at the posterior margin of the bulb that are OMP(-), 2C6(-), and MAb213(-). In summary, the current work indicates that glomeruli at the posterior margin of the bulb, which are necklace glomeruli in terms of location and appearance, are actually heterogeneous and may subserve specialized functions within the olfactory system.

FGF2 suppresses neuronogenesis of a cell line derived from rat olfactory epithelium.

Neurogenesis continues throughout adulthood in the mammalian olfactory epithelium (OE), and both neurons as well as nonneuronal cells are reconstituted following experimental injury. Underlying the capacity of the OE to replenish its mature elements is a population of progenitor basal cells. Although the precise lineage relationships among progenitor and mature cell types are incompletely understood, the population of globose basal cells (GBCs) contains immediate precursors to neurons as well as amplifying progenitors, and retroviral lineage analyses suggest that multipotential GBCs are activated following direct injury to the OE. To assess the controls on the process of epithelial regeneration, we have characterized a cell line derived from rat OE and studied the effects of serum and tissue extracts, fibroblast growth factor-2 (FGF2) and transforming growth factor-alpha (TGF alpha) on the cells. Using a panel of cell type-specific markers whose patterns of labeling in the OE are well defined, including recently developed markers for GBCs, we characterized the phenotype of the cell line under differing culture conditions. In complete medium, which contains serum and tissue extracts, the cell line displayed characteristics of GBCs that are prominent during regeneration. Serum and extract withdrawal induced the cells to differentiate into neurons. In contrast, FGF2 prevented neuronal differentiation and maintained a GBC phenotype. TGF alpha had a mitogenic or differentiative effect that was context dependent. Finally, we demonstrate here that FGF2 is contained in mature olfactory neurons and sustentacular cells in vivo, suggesting a physiologic role for this growth factor in OE cell regulation.

Odorant threshold following methyl bromide-induced lesions of the olfactory epithelium.

The present study assessed the functional consequences of peripheral olfactory destruction on the minimum detectable levels of stimulation for the odorants 2-propanol, D-limonene, and ethyl acetoacetate. Using standard operant techniques, eight Long-Evans rats were trained to criterion on an air versus odor differential response task. Odorant threshold was then determined on 10 consecutive testing sessions, using a computer-automated olfactometer and psychophysical tracking procedure. Following the last testing session, the rats were lesioned by exposing them to 330 ppm methyl bromide gas for 6 h. For each lesioned animal the anatomical state of the olfactory epithelium was evaluated relative to behavioral performance on the odorant threshold task at 3 days postlesion. For the group of rats, a comparison of pre- and postlesion performance demonstrated that, on the average, odor sensitivity was not altered by lesions that destroy roughly 95-98% of the epithelium. However, analysis of individual cases illustrated that two of the eight rats showed an elevation in odor sensitivity, albeit minimally, that was considered different from the prelesion performance. For those animals affected, we could extract no apparent relationship between the behavioral findings and the extent of anatomical damage. The results of this study demonstrate the remarkable capacity of the olfactory system to maintain normal or near-normal detection sensitivity in the face of massive damage. This capacity presumably reflects both the normal exposure of the epithelium to continual injury and the importance of maintained olfactory function for the survival of the animal.

The aging olfactory epithelium: neurogenesis, response to damage, and odorant-induced activity.

Olfactory epithelium retains the capacity to recover anatomically after damage well into adult life and perhaps throughout its duration. None the less, olfactory dysfunctions have been reported widely for elderly humans. The present study investigates the effects of aging on the neurophysiological and anatomical status of the olfactory epithelium in barrier-raised Fischer 344X Brown Norway F1 hybrid rats at 7, 10, 25 and 32/35 months old. The posterior part of the olfactory epithelium in 32/35-month-old rats is well preserved. Globose basal cells are dividing, and new neurons are being born even at this advanced age. None the less, the numbers of proliferating basal cells and immature, GAP-43 (+) neurons are significantly decreased. Neurophysiological status was evaluated using voltage-sensitive dye techniques to assess inherent patterns of odorant-induced activity in the epithelium lining the septum and the medial surface of the turbinates. In middle and posterior zones of the epithelium, there were neither age-related changes in overall responsivity of this part of the olfactory epithelium to any of five odorants, nor shifts in the location of the odorant-induced hotspots. The inherent activity patterns elicited by the different odorants do become more distinct as a function of age, which probably reflects the decline in immature neurons and a slight, but not statistically significant, increase in mature neurons as a function of age. In contrast with the excellent preservation of posterior epithelium, the epithelium lining the anterodorsal septum and the corresponding face of the turbinates is damaged in the 32/35-month-old animals: in this part, horizontal basal cells are reactive, more basal cells and sustentacular cells are proliferating than in younger animals or in posterior epithelium of the same animals, and the neuronal population is less mature on average. Our findings indicate that degeneration of the olfactory epithelium is not an inevitable or pre-programmed consequence of the aging process, since the posterior zone of the epithelium is very well preserved in these barrier-protected animals. However, the deterioration in the anterior epithelium suggests that environmental insults can accumulate or become more severe with age and overwhelm the regenerative capacity of the epithelium. Alternatively, the regenerative capacity of the epithelium may wane somewhat with age. Either of these mechanisms or some combination of them can account for the functional and anatomical deterioration of the sense of smell associated with senescence in humans.

Time course of troponin I, myoglobulin, and cardiac enzyme release after electrical cardioversion.

The results of this study, conducted in 25 patients without myocardial infarction, showed that all the biologic markers of myocardial infarction, except the highly cardiospecific cardiac troponin I, increased in some patients after electrical cardioversion. These results allow us to conclude that electrical cardioversion, even preceded by a mechanical resuscitation of short duration, does not result in myocardial damage, and that cardiac troponin I is more accurate than creatine kinase-MB activity and creatine kinase-MB mass determination for the diagnosis of myocardial damage in patients who have undergone electrical cardioversion.

Analysis of the globose basal cell compartment in rat olfactory epithelium using GBC-1, a new monoclonal antibody against globose basal cells.

The olfactory epithelium (OE) supports ongoing neurogenesis throughout life and regenerates after experimental injury. Although evidence indicates that proliferative cells within the population of globose (light) basal cells (GBCs) give rise to new neurons, little is known about the biology of GBCs. Because GBCs have been identifiable only by an absence of staining with reagents that mark other cell types in the epithelium, we undertook to isolate antibodies that specifically react against GBCs and to characterize the GBC compartment in normal and regenerating OE. Monoclonal antibodies were produced using mice immunized with regenerating rat OE, and a monoclonal antibody designated GBC-1, which reacts against GBCs of the rat OE, was isolated. In immunohistochemical analyses, antibody GBC-1 was found to label GBCs in both normal and regenerating OE as we are currently able to define them: basal cells that incorporate the mitotic tracer bromodeoxyuridine and fail to express cytokeratins or neural cell adhesion molecule. During epithelial reconstitution after direct experimental injury with methyl bromide, expression of the GBC-1 antigen overlaps to a limited extent with expression of cell-specific markers for horizontal basal cells, Bowman's gland and sustentacular cells, and neurons. These data suggest that GBC-1 may mark multipotent cells residing in the GBC compartment, which are prominent during regeneration. However, a limited number of cells in the regenerating OE with other phenotypic characteristics of GBCs lack expression of the GBC-1 antigen. GBC-1 has revealed novel aspects of GBC biology and will be useful for studying the process of olfactory neurogenesis.