Natural History of Perianal Fistulising Lesions in Patients With Elderly-onset Crohn's Disease: A Population-based Study

INTRODUCTION

Most studies of elderly-onset Crohn's disease [CD; diagnosed in patients aged 60 or over] have described a mild course. However, data on the natural history of perianal fistulising CD [pfCD] in this population are scarce. In a population-based cohort study, we described the prevalence, natural history, and treatment of pfCD in patients with elderly-onset CD vs patients with paediatric-onset CD.

METHOD

All patients diagnosed with CD at or after the age of 60 between 1988 and 2006, were included [n = 372]. Logistic regression, Cox models, and a nested case-control method were used to identify factors associated with pfCD.

RESULTS

A total of 34 elderly patients [9% of the 372] had pfCD at diagnosis. After a median follow-up of 6 years (interquartile range [IQR]: 3; 10), 59 patients [16%] had pfCD; the same prevalence [16%] was observed in paediatric-onset patients. At last follow-up, anal incontinence was more frequent in elderly patients with pfCD than in elderly patients without pfCD [22% vs 4%, respectively; p < 10-4]. Rectal CD at diagnosis was associated with pfCD: hazard ratio (95% confidence interval [CI] = 2.8 [1.6-5.0]). Although 37% of the patients received immunosuppressants and 17% received anti-tumour necrosis factor agents, 24% [14 out of 59] had a definitive stoma at last follow-up.

CONCLUSION

During the first 6 years of disease, the prevalence of pfCD was similar in elderly and paediatric patients. Rectal involvement was associated with the appearance of pfCD in elderly-onset patients. Around a quarter of patients with elderly-onset CD will have a stoma. Our results suggest that treatment with biologics should be evaluated in these patients.

Dramatic Increase in Incidence of Ulcerative Colitis and Crohn's Disease (1988-2011): A Population-Based Study of French Adolescents

OBJECTIVES

Few data are available to describe the changes in incidence of pediatric-onset inflammatory bowel disease (IBD). The aim of this study was to describe changes in incidence and phenotypic presentation of pediatric-onset IBD in northern France during a 24-year period.

METHODS

Pediatric-onset IBD (<17 years) was issued from a population-based IBD study in France between 1988 and 2011. Age groups and digestive location were defined according to the Paris classification.

RESULTS

1,350 incident cases were recorded (8.3% of all IBD) including 990 Crohn's disease (CD), 326 ulcerative colitis (UC) and 34 IBD unclassified (IBDU). Median age at diagnosis was similar in CD (14.4 years (Q1=11.8-Q3=16.0)) and UC (14.0 years (11.0-16.0)) and did not change over time. There were significantly more males with CD (females/males=0.82) than UC (females/males=1.25) (P=0.0042). Median time between onset of symptoms and IBD diagnosis was consistently 3 months (1-6). Mean incidence was 4.4/10⁵ for IBD overall (3.2 for CD, 1.1 for UC and 0.1 for IBDU). From 1988-1990 to 2009-2011, a dramatic increase in incidences of both CD and UC were observed in adolescents (10-16 years): for CD from 4.2 to 9.5/10⁵ (+126%; P<0.001) and for UC, from 1.6 to 4.1/10⁵ (+156%; P<0.001). No modification in age or location at diagnosis was observed in either CD or UC.

CONCLUSIONS

In this population-based study, CD and UC incidences increased dramatically in adolescents across a 24-year span, suggesting that one or more strong environmental factors may predispose this population to IBD.

Extra-intestinal Manifestations at Diagnosis in Paediatric- and Elderly-onset Ulcerative Colitis are Associated With a More Severe Disease Outcome: A Population-based Study

BACKGROUND AND AIMS

Data on extra-intestinal manifestations [EIM] and their impact on the disease course of ulcerative colitis [UC] in population-based cohorts are scarce, particularly in paediatric- and elderly-onset UC patients. The aims of this population-based study were to assess: 1] the occurrence of EIM in paediatric- and elderly-onset UC; 2] the factors associated with EIM; and 3] their impact on long-term disease outcome.

METHODS

Paediatric-onset [< 17 years at diagnosis] and elderly-onset UC patients [> 60 years at diagnosis] from a French prospective population-based registry [EPIMAD] were included. Data on EIM and other clinical factors at diagnosis and at maximal follow-up were collected.

RESULTS

In all, 158 paediatric- and 470 elderly-onset patients were included [median age at diagnosis 14.5 and 68.8 years, median follow-up 11.2 and 6.2 years, respectively]. EIM occurred in 8.9% of childhood- and 3% of elderly-onset patients at diagnosis and in 16.7% and 2.2% of individuals during follow-up [p < 0.01], respectively. The most frequent EIM was joint involvement [15.8% of paediatric onset and 2.6% of elderly-onset]. Presence of EIM at diagnosis was associated with more severe disease course [need for immunosuppressants or biologic therapy or colectomy] in both paediatric- and elderly-onset UC (hazard ratio [HR] = 2.0, 95% confidence interval [CI]: 1.0-4.2; and HR = 2.8, 0.9-7.9, respectively). Extensive colitis was another independent risk factor in both age groups.

CONCLUSIONS

Elderly-onset UC patients had lower risk of EIM either at diagnosis or during follow-up than paediatric-onset individuals. EIM at diagnosis predicted more severe disease outcome, including need for immunosuppressive or biologic therapy or surgery, in both paediatric- and elderly-onset UC.

Bluetongue dynamics in French wildlife: exploring the driving forces

Bluetongue (BT) was monitored in wildlife in France during two consecutive years corresponding to contrasting incidence rates in livestock: in 2008 at the peak of domestic outbreaks and in 2009 when very few outbreaks were observed. The disease status of 2 798 ruminants comprising 837 red deer (Cervus elaphus) was explored using ELISA test on serum and real-time RT-PCR test on blood or spleen. A large proportion of red deer were seropositive and positive to RT-PCR in 2008, but also in 2009 (seroprevalence: 47.1% and 24.3%), suggesting that red deer could maintain infection when domestic incidence was negligible. By contrast, low seroprevalence (<3%) and few RT-PCR positive results were observed in other wild ruminant species, which rather appeared thus as dead-end hosts. The risk factors of bluetongue circulation during the periods of high (2008) and low (2009) domestic incidence were explored in red deer using logistic mixed models. In this species, prevalence has been mainly influenced by the initial peak of BT in livestock, but also by environmental factor such as elevation and edge density between forest and pastures. Surprisingly, cattle density has a negative influence on prevalence in red deer, possibly due to the protective effect of cattle regarding midges' bites and/or to still unexplained factors dealing with the host/midge interface. To our knowledge, this study is the first attempt at measuring the effect of landscape and wildlife/domestic interface on BT prevalence in wildlife in Europe.

Age-related male reproductive effort in two mountain ungulates of contrasting sexual size dimorphism

In polygynous ungulates, the reproductive effort of adult males peaks during a short period in which feeding activities are sacrificed for mating activities. Hence, both fat reserves and body mass are predicted to decline markedly during this period. The decline is also predicted to be greater in fat reserves than in body mass because fat is catabolized before muscle, and to increase with the intensity of sexual selection. In contrast, no specific patterns are expected in females for which late gestation and lactation rather than mating are the energetically most demanding periods. We tested these hypotheses in two mountain ungulates of contrasting sexual size dimorphism (SSD): Himalayan tahr ( Hemitragus jemlahicus (H. Smith, 1826)) (SSD = 123%) and alpine chamois ( Rupicapra rupicapra (L., 1758)) (SSD = 26%). As expected, kidney fat declined more rapidly than body mass in adult males of both species. Kidney fat declined faster in adult male tahr compared with adult male chamois. There was no consistent pattern of changes in body mass or kidney fat in female tahr or female chamois. Our results suggest that adult males of species with strong SSD allocate more energy to mating than males of less dimorphic species.

Daily responses of mouflon (Ovis gmelini musimon ×Ovis sp.) activity to summer climatic conditions

Investigating the factors shaping the activity of large herbivores is of prime importance because changes in their activity patterns may indicate physiological stress, which can affect reproduction and survival of individuals, and thereby population growth. Although climatic conditions are known to impact the activity patterns of large herbivores, few studies have investigated this relationship at a fine temporal scale. From a continuous monitoring of activity, we assessed the influence of temperature and wind on the summer activity of female mouflon ( Ovis gmelini musimon Pallas, 1811 × Ovis  sp.) facing summer droughts. Females showed a marked bimodal activity pattern, with activity peaks occurring after dawn and before dusk. When temperature increased and wind speed decreased, the morning activity peak occurred earlier, while the evening activity peak was delayed. Hence, under stressing climatic conditions, female mouflon decreased their diurnal activity while increasing their nocturnal activity. However, this nocturnal increase did not prevent the activity rate over 24 h to decrease during hot nonwindy days compared with cool windy days. Although the occurrence of wind mitigated the negative influence of heat on the diurnal activity, wind had no effect at the daily scale. These findings emphasize the importance of working at different temporal scales when assessing the activity patterns of free-ranging vertebrates.

Molecular and biological characteristics of Toxoplasma gondii isolates from wildlife in France

Toxoplasma gondii isolates have been classified into 3 genetic types. Little is known about genotypes of T. gondii isolates in wild animals in Europe. In this report, genotypes of T. gondii isolates from wildlife in France are described. Sera from wildlife were tested for antibodies to T. gondii with the modified agglutination test, and the hearts from animals with titers superior or equal to 1:6 were bioassayed individually in mice. T.gondii was isolated from 9 of 14 seropositive red foxes (Vulpes vulpes), 12 of 33 roe deer (Capreolus capreolus), 1 of 4 deer (Cervus elaphus), 1 of 7 mouflons (Ovis gmelini musimon) and 1 of 2 common mallards (Anas platyrhynchos). No isolate was obtained by bioassay in mice of 1 fallow deer (Dama dama) and of 3 European brown hares (Lepus europaeus). Genotyping of the 24 isolates using PCR-RFLP and microsatellite markers indicated that all were type II and none of these Toxoplasma isolates was virulent for mice.

Determinants of seasonal variation in activity patterns of mouflon

Balancing energetic requirements is a complex process governed by the current condition of the animal, its physiological state, and by the local environment. In response to these factors, animals are expected to adapt their activity patterns. Based on continuous monitoring of 14 GPS-collared animals in southern France, we studied how environmental conditions and reproductive life-cycle periods shape the monthly activity patterns of free-ranging female mouflon ( Ovis gmelini musimon  × Ovis sp. (Blyth, 1841)). More specifically, we analyzed total daily activity, diurnal activity, length of activity bouts, and number of activity bouts. We performed multivariate analyses to account for the relationship between several intercorrelated explanatory variables and monthly activity variables. Mouflon decreased their daily activity, diurnal activity, and length of activity bouts during the hot summer months. Such changes might allow animals to reduce thermoregulation costs. The resulting higher activity in winter compared with summer indicates that summer is the most limiting period for large herbivores in Mediterranean area. Both the number of active bouts and the daily activity increased during spring, when females have access to increased food quality, which ensures a faster digestion, and when they may face high energetic requirements owing to reproduction.

Age- and sex-specific settlement patterns of chamois (Rupicapra rupicapra) offspring

The social, spatial, and genetic structures of populations depend on where offspring settle and reproduce in relation to their parent’s home range. However, the patterns of settlement in wild populations of large mammals are often poorly described owing to the difficulty of monitoring mother–offspring pairs over a long period. Here, we investigated sex-specific settlement patterns in chamois ( Rupicapra rupicapra (L., 1758)) based on the study of 31 mother–offspring pairs. We calculated the distance between the center of the mother’s range and the center of her offspring’s range, and tested whether this distance differed when the offspring was immature (i.e., a yearling) and after offspring sexual maturity (>2 years of age). We found no sex effect on the distance between centers of mother and offspring ranges for yearling offsprings. However, mature sons ranged farther away from their mother than mature daughters. Daughters appear to settle close to their mother’s home range. The distance at which a daughter settles compared with her mother’s range seems to be determined before 2 years of age. On the contrary, the distance between the center of the locations of yearling males and the center of locations of their mother does not predict how far away males will eventually settle when mature. We discuss the implications of these patterns for generating female social structures, as well as population spatial and genetic structures.

Gastroesophageal reflux in patients with morbid obesity: a role of obstructive sleep apnea syndrome?

BACKGROUND

Obesity is a risk factor for gastroesophageal reflux disease (GERD) and for obstructive sleep apnea (OSA). Our aim was to evaluate in morbidly obese patients the prevalence of OSA and GERD and their possible relationship.

METHODS

Morbidly obese patients [body mass index (BMI) >40 or >35 kg/m(2) in association with comorbidities] selected for bariatric surgery were prospectively included. Every patient underwent a 24-h pH monitoring, esophageal manometry, and nocturnal polysomnographic recording.

RESULTS

Sixty-eight patients [59 women and 9 men, age 39.1 +/- 11.1 years; BMI 46.5 +/- 6.4 kg/m(2) (mean +/- SD)] were included. Fifty-six percent of patients had an abnormal Demester score, 44% had abnormal time spent at pH <4, and 80.9% had OSA [apnea hypopnea index (AHI) >10] and 39.7% had both conditions. The lower esophageal sphincter (LES) pressure was lower in patients with GERD (11.6 +/- 3.4 vs 13.4 +/- 3.6 mm Hg, respectively; P = 0.039). There was a relationship between AHI and BMI (r = 0.337; P = 0.005). Patients with OSA were older (40.5 +/- 10.9 vs 33.5 +/- 10.4 years; P = 0.039). GERD tended to be more frequent in patients with OSA (49.1% vs 23.1%, respectively; P = 0.089). There was no significant relationship between pH-metric data and AHI in either the 24-h total recording time or the nocturnal recording time. In multivariate analysis, GERD was significantly associated with a low LES pressure (P = 0.031) and with OSA (P = 0.045) but not with gender, age, and BMI.

CONCLUSION

In this population of morbidly obese patients, OSA and GERD were frequent, associated in about 40% of patients. GERD was significantly associated with LES hypotonia and OSA independently of BMI.

Social and spatial patterns determine the population structure and colonization processes in mouflon

Although it is widely accepted that populations vary in space and time, defining the spatial scale of population structure relevant for understanding temporal variation or for management and conservation purposes remains a challenge. We studied jointly temporal patterns of social and spatial structures in an introduced population of mouflon ( Ovis gmelini musimon (Schreber, 1782)) to define the temporal stability of these structures and to uncover the history of the colonization process. We expected social organization to remain stable between years, mouflon to stay sedentary, and colonization to have occurred through a diffusion process. We used yearly censuses performed between 1994 and 2004, and collected information in managers’ archives and newspapers reporting the presence of mouflon in different areas since its introduction in 1954 in the Bauges mountains, France. Mouflons were divided into male and nursery groups, whose number (1.88 ± 0.31 for males and 7.54 ± 0.58 for nurseries) and composition (7.05 ± 1.25 individuals in male groups; 13.6 ± 1.41 females, 8.11 ± 0.72 lambs, and 6.51 ± 0.65 males in the nurseries) remained stable over years. The spatial distribution of nursery groups was clustered in five areas, highly correlated between years (p < 0.001), suggesting that the same groups were observed in given areas every year and confirming the sedentary lifestyle of the species. The presence–absence data of the species since its introduction suggested a colonization by diffusion. We discuss the social and spatial structures of the population and the type of colonization process that could have led to this kind of structure.

The effects of a severe drought on mouflon lamb survival

The mouflon population of Caroux-Espinouse, southern France, inhabits a highly seasonal area with dry summers. We monitored summer lamb survival during a severe drought in 2003, from early June to late August. The survival of 35 radio-tagged lambs over nine two-week periods was strongly affected by the timing of rainfall. Survival depended on the amount of rainfall recorded at a given 14 day period and in the previous 14-21 day period. Survival was not influenced by the exceptionally high mean daily temperature recorded during some periods. Male lamb survival (0.68) tended to be less than female survival (0.81), although not significantly, possibly because of a low sample size. The high lamb mortality (25.7%) recorded during a four-month period is much higher than previous estimates of first-year mortality (less than 10%). We recommend accounting for climatic variation in summer when studying the population dynamics of ungulates.

[Undergraduate medical education. Students' perspective and medical school policy]

OBJECTIVES

Student attendance to lectures in French medical schools is often poor. We surveyed undergraduate medical students in our medical school, repeating a similar survey conducted ten years earlier. The results are presented with the conclusions of the faculty seminar that followed this survey.

METHODS

A closed item questionnaire was distributed in June, 1998, through the hospital wards where the students were posted. After two reminders, the final response rate was 71% (247/348).

RESULTS

Overall, 71% of the students declared that they never, or only occasionally, attended lectures in the medical school. Reasons included lack of time (75%), the curriculum diverging from the program of the selective examination that gives access to graduate specialization programs (59%), or insufficient practical clinical content (36%); 46% believed that this teaching prepared them to practice family medicine (11% some specially), and 92% that the way it was organized was not compatible with preparing for the selective examination. On the other hand, 75% of the students in the final two years of the curriculum declared that attending regularly special preparation seminars for the selective examination, to succeed at this test (91%), but also to prepare for family practice (25%). Respectively, 75%, 68% and 66% declared that undergraduate medical courses should, ideally, prepare them for the selective examination, but also for the practice of family medicine, and for graduate medical education.

CONCLUSIONS

These results echoed the difficulties of the faculty of the medical school to reconcile preparing students both for their future medical practice and for the selective examination. Two working groups were asked to identify independently appropriate educational objectives according to each perspective: their conclusions appeared to be quite compatible. Based on these conclusions, institutional objectives were ratified to guide the educational policy of our medical school, including the following: to reinforce the consistency and progressiveness of the curriculum; to promote active and autonomous student learning approaches; to develop faculty teaching skills, curriculum evaluation and recognition of teaching activities.

Testing of the AVL OPTI 1 portable blood gas analyzer during inflight conditions

The "AVL OPTI 1" (AVL Medical Instruments, Saint-Ouen l'Aumone, France), a completely automated portable blood gas analyzer, was chosen because of its accuracy under usual sea-level conditions and because of its new technology which broadens the possibilities for in-flight blood determinations: a) a single use cassette made of plexyglass containing the measurement chamber and the aligned sensors required for pO2, pcO2 and pH determination; b) calibration coefficients memorized in a bar code label fixed on the packing material; c) a quality control of each individual cassette prior to the measurement and at least once a day by two standard reference cassettes simulating high and low levels of pH, pcO2 and pO2; and d) a fully automatic introduction of the blood sample. The complete analytical cycle requires about 3 min with a sample volume of 80 microL of whole blood. After the measurement, the cassette containing blood sample is destroyed. Moreover, this device uses optical electrodes or "optodes" (fluorescence sensors). We tested the accuracy and imprecision of pO2 and pcO2 sensors on fresh blood which was equilibrated with four different gas mixtures at four different altitudes (250, 8000, 10,000 and 13,000 ft), simulated in a decompression chamber. Gas measurement optodes had linear responses and were accurate for all measured pO2 and pco2 values (n = 66), except for at high values of PO2 (>150 mmHg) and pco2 (>65 mmHg). The pressure value given by the AVL OPTI 1 was controlled before the experiment began and during the different depression levels. Barometric pressure results showed: a) concordance of pressure values with those of ground instrumentation; b) stable response; and c) absence of hysteresis. We conclude that the performance of the AVL OPTI 1 is satisfactory during inflight conditions.

Pressure-heart rate responses to alpha-adrenergic stimulation and hormonal regulation in normotensive patients with obstructive sleep apnea

Seven normotensive untreated patients with obstructive sleep apnea (OSA) and five control subjects without OSA were compared. Patients with cardiac dilation, chronic airflow limitation, liver and kidney disease, or diabetes mellitus were excluded. Change in pressure-heart rate relation to alpha-adrenergic stimulation (P-HRR), extracellular volume (ECV), and plasma volume (Vp) were measured during daytime. Plasma atrial natriuretic peptide (ANP), plasma renin and aldosterone concentrations were obtained at 1 hour intervals during the night. A mean apnea/hypopnea index (AHI) of 52.2 +/- 23.9/h and a mean lowest arterial oxygen saturation (SaO2) of 61.2 +/- 19.3% (mean +/- SD) were determined from polysomnographic monitoring in the patient group. Release of ANP was significantly higher during sleep in OSA patients than in control subjects (P < .01), with a maximum concentration between 4 and 6 AM in the former. Daytime ECV was significantly higher (P < .05) and Vp significantly lower (P < .05) in OSA patients. Night maximum concentration of ANP (max ANP) was negatively related to AHI (P < .05). P-HRR was negatively related to AHI (P < .05) and positively related to max ANP (P < .05). In conclusion, OSA syndrome alters hormonal system control of body fluid compartment regulation. The decreased response in night max ANP secretion in the most severe OSA patients could be explained by the smaller Vp observed in these patients, decreasing atrial and ventricular pressure loading. Furthermore, alteration of P-HRR, correlated to AHI and max ANP, strengthens the hypothesis that patients who develop hypertension are those in whom the protective mechanism of ANP release failed.

Fiberoptic bronchoscopy for the early diagnosis of subglottal inhalation injury: comparative value in the assessment of prognosis

The aim of this study was to determine the value of bronchoscopy in the early diagnosis of inhalation injury. A total of 130 burn patients underwent bronchoscopy on admission to a specialized center. In order to validate the method and the bronchoscopist's conclusions, they underwent staged bronchial biopsies. Using the histologic findings as the "gold standard," bronchoscopy proved to be sensitive (sensitivity, 0.79) and highly specific (specificity, 0.94) for the diagnosis of inhalation injury. In addition, it was more reliable than the circumstances of the injury, the clinical findings, and complementary tests. In a one-dimensional analysis, bronchoscopy-proven inhalation injury was one of the most strongly predictive variables for the onset of ARDS and death. The analysis of survival curves confirmed that inhalation injury portends a bad outcome in burn patients. It was used to predict the likelihood of ARDS and death at the time of admission with a view to early specific treatment.

Cost effectiveness of noninvasive oxygen saturation measurement during exercise for the diagnosis of Pneumocystis carinii pneumonia

We assessed (1) the sensitivity and specificity of exercise oxygen saturation measurement (EOS) for the diagnosis of Pneumocystis carinii pneumonia (PCP); and (2) the cost of introducing this indirect diagnostic test compared with that of standard diagnostic strategies for PCP. In a prospective study, 85 HIV-infected patients with suspected PCP underwent EOS, followed by induced sputum (IS) and bronchoalveolar lavage (BAL) if IS was negative for P. carinii. The prevalence of PCP was 0.22, the sensitivity of IS was 0.6, and its specificity was perfect. The cost ratios of IS to BAL and EOS to BAL were 0.1 and 0.2, respectively. A desaturation of three points was the best cutoff point, giving perfect sensitivity and a specificity of 0.77. The cost analysis showed that the introduction of EOS into diagnostic strategies for PCP is highly justified when the local prevalence is low. Exercise oxygen saturation measurement is simple and safe, and the results are available rapidly; its sensitivity is perfect and its specificity good. Its economic utility depends on its cost and the local prevalence of PCP in the test population.

Decreased oxyhemoglobin affinity in patients with sleep apnea syndrome

Oxyhemogloblin affinity (P50 at pH 7.4, PaCO2 = 40 mm Hg, temperature = 37 degrees C) and 2,3-DPG concentration were assessed in 15 nonsmokers (14 men and one woman 46 to 63 yr of age) with sleep apnea syndrome (SAS) and in 10 normal subjects (eight men and two women 22 to 48 yr of age). In patients with SAS, mean nocturnal apnea index was 46 +/- 20/h, and mean nocturnal SO2 was 86 +/- 6% versus 94.6 +/- 1.8% during the daytime. Daytime mean P50 of the patients was 28.5 +/- 1.2 mm Hg versus 27.1 +/- 0.3 mm Hg in the normal subjects (p less than 0.05). Daytime mean 2.3-DPG was 1.23 +/- 0.25 moles DPG/mole hemoglobin versus 0.80 +/- 0.15 (p less than 0.05). Significant correlations were found in patients between P50 and mean nocturnal SO2 (r = -0.62, p less than 0.01) and between P50 and 2,3-DPG (r = 0.68, p less than 0.01). The measurements were repeated in five patients after surgical or positive-pressure treatment. P50 and 2,3-DPG both decreased and returned to normal values. In conclusion, the oxyhemoglobin dissociation curve is shifted to the right in patients with SAS and there is an increase in 2,3-DPG. These could be protective mechanisms against the development of polycythemia, pulmonary hypertension, and cor pulmonale.

Ventilatory adjustments during sustained resistive unloading in exercising humans

Effect of He-O2-breathing (79.1%:20.9%) compared to air-breathing on inspiratory ventilation (VI) and its different components [tidal volume (VT), the duration of the phases of each respiratory cycle (tI, tTOT)] as well as on inspiratory mouth occlusion pressure (P0.1) were studied in six normal men at rest and during 72 constant-load exercises (90 W) over a much longer period than in previous studies. Results showed that, irrespective of the order of administration of the two gases (7 min air----7 min He-O2 or vice versa): at rest, P0.1 decreased during He-O2 inhalation but no changes in VI and breathing pattern were detectable; during exercise, sustained He-induced hyperventilation was observed without any change in the absolute value of P0.1; increase in P0.1 between the resting period and exercise (delta P0.1) was significantly higher during He-O2-breathing than during air breathing; this He-induced hyperventilation was associated with a sustained increase in VT/tI, but with constant tI/tTOT. Helium-breathing during exercise cannot be a simple situation of resistance unloading, as has been suggested. We conclude that He-O2-breathing, after the initial compensation period, induces reflex changes in ventilatory control with an increase in inspiratory neural drive. Moreover, it appears that exercise P0.1 is not a legitimate index of inspiratory neural drive whenever rest P0.1 changes according to the nature of the inhaled gas mixture.

The determination of total haemoglobin as haemiglobin

This study describes a new method for routine total haemoglobin determination by conversion to haemiglobin (Hi), and compares it with the haemiglobin cyanide (HiCN) method. Experiments were performed in two phases. Firstly, the absorbance coefficient (epsilon Hi,500mm) at pH = 6.8, determined from 24 blood samples, was found to be 998 +/- 31 m2.mol-1. Secondly, using this value of epsilon, the range of haemoglobin concentration measured was 3.7 to 19.2 mmol.l-1 (6 to 31 g.dl-1). The correlation data shows an excellent correlation (r = 0.982, p less than 0.001) with the reference procedure. Reproducibility and accuracy were shown to be good.

Protective effect of vasodilators on liver function after long hypothermic preservation: a study in the isolated perfused rat liver

The effects of two vasodilators, papaverine and pentoxifylline (a methylxanthine derivative), on liver function after 19 hr hypothermic preservation were investigated. Hypothermic preservation was performed according to the standard technique, and liver hemodynamics and function were studied during 70 min immediately after reperfusion in an isolated perfused rat liver system. No significant changes occurred after hypothermic storage for 5 hr. However, when the storage was prolonged to 19 hr, bile flow and taurocholate intrinsic clearance were significantly reduced; transaminase release was markedly increased and histological studies demonstrated centrilobular necrosis. Concomitantly, liver blood flow was significantly reduced and intrahepatic vascular resistance was increased. Papaverine and pentoxifylline administered during preservation and at the time of reperfusion significantly improved all parameters. The improvement was more pronounced after pentoxifylline, and this group showed no significant difference in any of the studied parameters from the control livers. The results show that two vasodilators significantly protect the liver during long hypothermic preservation. The data suggest that abnormalities of liver microcirculation are of major importance in the pathogenesis of liver injury after hypothermic storage.

Testing of the Eschweiler 2500-11 blood gas analyser during inflight conditions

Measurement of blood gas values during air transport of intensive care patients must take into account the extreme inflight variations in pressure. We tested the accuracy and reliability of the Eschweiler 2500-11 apparatus, with its incorporated pressure transducer, on four different gas mixtures equilibrated with fresh blood at two different altitudes simulated in a decompression chamber. Results for the pressure transducer show: 1) concordance of pressure values with those of ground instrumentation; 2) stable response; and 3) absence of hysteresis. Gas measurement electrodes were shown to have linear responses and were accurate for all tested values except very low PCO2 and very high PO2 figures. We conclude that the performance of this device is satisfactory during inflight conditions.

Effect of He-O2 breathing on blood gases and ventilation during exercise in normal man

Temporal changes in ventilation (VI) and arterial blood gases after substitution of helium (He) for nitrogen were studied in normal man during constant load exercises of 14 min duration (30 and 90 W). An abrupt switch of helium for air breathing (protocol 1; 5 subjects), or vice-versa (protocol 2; 4 subjects), was made at the 7th min. Whatever the work loads, the effect of He appeared rapidly: higher values of VI (protocol 1) were observed throughout the 7 min period of He-O2 breathing, but were only significant (p less than or equal to 0.05) during the first minute after substitution at 90 W. Reverse pattern was observed in protocol 2. Helium induced alveolar hyperventilation: sustained and significant hypocapnia (p less than or equal to 0.05) was observed during helium breathing. This effect does not seem to be a consequence of pulmonary gas exchange disturbance, in that concomitant Po2 was normal. It is suggested that He could have evoked a reflex which overrode humoral regulation. Significant increase in ventilatory CO2 responses at rest during He-O2 compared to air breathing in seven subjects (p less than or equal to 0.01) seems to confirm this hypothesis.

[Spirometric monitoring of the effects of puncturing thoracic pain points in asthmatic disease]

The effects of puncture of thoracic pain points on ventilatory abnormalities were studied in 17 asthmatic subjects. For the tested group (n = 8), the painful character of the points was the only criterion for the choice of puncture sites. References to classical acupuncture points were not made. The points chosen for the control group (n = 9) were in extrathoracic zones (lower limbs). VEMS was significantly higher (p less than 0.05) after puncture of thoracic pain points whereas no shift was observed after puncture in the extrathoracic zone. VC was not modified by either technique.

[Cholesterol crystals and biliary lithiasis. Importance of the study of bile collected by duodenal intubation]

Cholesterol crystallization in a necessary step in the formation of cholesterol gallstones. Our purpose was to study the relationship between the presence of biliary cholesterol crystals and radiolucent gallstones. Bile was obtained by duodenal intubation from 60 subjects free of hepatic disease: 40 patients had radiolucent gallstones and in the remaining 20 subjects no gallstones could be found either by oral cholecystography or by ultrasound examination. In each patient a bile sample was used to search for cholesterol crystals; in another sample, biliary cholesterol, phospholipids and bile acids were measured to calculate the lithogenic index. Among the 44 subjects with lithogenic bile, 34 had radiolucent gallstones. Twenty-two out of the 60 patients had both cholesterol crystals and radiolucent gallstones; 21 subjects out of the 22 had lithogenic bile. In patients with frequent biliary colic or subacute pancreatitis without visible gallstones, finding cholesterol crystals in bile might suggest medical or surgical specific treatment.

Depressive effect of coughing on spinal monosynaptic reflexes in conscious man

1. The relationship between coughing and spinal monosynaptic reflexes (SMR) in extensors and flexors was investigated in eight healthy subjects by using the Hoffmann technique. Coughing exerted major depression (81% in extensor and 83% in flexor SMR). This depressant effect began simultaneously with the first cough and lasted through the coughing phase. Complete recovery to initial values occurred an average of 40 s thereafter. 2. In comparison, mental tasks induced only a slight decrease in SMR amplitude. In contrast, the Mueller and Valsalva manoeuvres induced facilitation. 3. During coughing, large variations in extensor amplitudes were observed that were coupled with the ventilatory cycle. Slight facilitation was observed during inspiration, but expiration induced pronounced depression, occurring 0.20 s after the beginning of the expiratory period. Experiments performed during baseline breathing failed to show any change throughout inspiratory or expiratory phases. 4. Chemical stimulation of irritant receptors (inhalation of citric acid) produced no specific modification of extensor responses compared with the effect of placebo inhalation (distilled water). 5. These data suggest that coughing exerts a major depressant effect on motor activity via a loop that possibly includes cardiopulmonary receptors and inhibitory supraspinal descending pathways.

Gas exchange during bicycle exercises preceded or not by loadless pedalling in female and male subjects

The effects on ventilation and oxygen uptake of pedalling with no load on the ergometer before exercise have been investigated in 10 subjects (6 males and 4 females). It has been found that: (1) the O2-deficit calculated at the beginning of exercise is less variable and generally reduced when exercise has been preceded by a loadless pedalling period; (2) for a given steady-state VO2, the O2-deficit is larger in female than in male subjects; (3) the respiratory equivalents for oxygen and for carbon dioxide are not affected by loadless pedalling; they are generally larger in female than in male subjects; (4) the increase in ventilation at the beginning of exercise is smaller after loadless pedalling but this seems to be apparent only in male subjects; (5) the pattern of breathing and heart rate are not affected by loadless pedalling. It is concluded that pedalling with no load on the ergometer before the exercise prepares the subject to deliver oxygen more rapidly to the muscles. It then reduces the variability in gas exchanges and the O2-deficit. Several factors which may account for this better efficiency of oxygen delivery are discussed.

Gas exchanges during exercise in normoxia and hyperoxia

Exercises of constant workload (90 watt) have been carried out during normoxia or hyperoxia FIO2 = 0.45). It has been shown that, in spite of a significant dispersion in the values of O2 deficit and O2 debt calculated, these values are related to the increased blood lactate level which contributes to the marked acidosis observed in both conditions of oxygenation. Hyperoxia reduces lactate level as well as the O2 debt. In addition to the significant increase in arterial [H+] and PCO2, exercise provokes a slight decrease in PO2. It is suggested that the significant variations of these humoral factors might contribute to the control of ventilation during exercise in both conditions of oxygenation.