Biomedical subjects

C Exner

Publications and source records attributed to C Exner.

11 recordsLinked to original sources

PubMed2006

Telemetric monitoring of tracheal pressure after tracheal occlusion for treatment of severe congenital diaphragmatic hernia.

INTRODUCTION: Prenatal tracheal occlusion using endoscopic techniques obstructs the normal egress of lung fluid during pulmonary development and stimulates lung growth in cases of congenital diaphragmatic hernia (CDH). Although FETO might be an effective strategy for treatment of CDH, the mechanism especially due to the supposed increasing transpulmonary pressure is unknown. OBJECTIVE: The purpose of this study was to monitor the pressure below the attached balloon in the fetal lamb telemetrically. METHODS: Four time-dated pregnant Merino ewes underwent fetal and maternal surgery. A special prepared silicone catheter was placed below the epiglottis by laryngoscopy on day 110 or 140 of gestation. The tracheal pressure below the fixed catheter could be monitored telemetrically using the Data Sciences TA11-PA-C40 pressure device. Hundred and twenty measurement points were recorded over a period of 2 min. RESULTS: A maximum of lung pressure rate was found immediately after implantation (23.7 +/- 4.6 mm Hg). During the first hour, the pressure decreased to an average value of 16.9 mmHg. About 70 h after the block, this value decreased to a minimum level of 8.3 +/- 0.4 mmHg. CONCLUSION: Decreasing pressure variation might indicate that lung growth has stopped and that the ideal point of time to remove the balloon is achieved. Increasing pressure has to be related to the morphometric analysis of the lung's structural development and maturation, comparing the efficacy of FETO in preventing or reversing pulmonary hypoplasia. Further investigation of continuous telemetric monitoring of tracheal pressure in the fetal lamb is required.

Animals↗

PubMed2006

PC1/3 and PC2 gene expression and post-translational endoproteolytic pro-opiomelanocortin processing is regulated by photoperiod in the seasonal Siberian hamster (Phodopus sungorus).

A remarkable feature of the seasonal adaptation displayed by the Siberian hamster (Phodopus sungorus) is the ability to decrease food intake and body weight (by up to 40%) in response to shortening photoperiod. The regulating neuroendocrine systems involved in this adaptation and their neuroanatomical and molecular bases are poorly understood. We investigated the effect of photoperiod on the expression of prohormone convertases 1 (PC1/3) and 2 (PC2) and the endoproteolytic processing of the neuropeptide precursor pro-opiomelanocortin (POMC) within key energy balance regulating centres of the hypothalamus. We compared mRNA levels and protein distribution of PC1/3, PC2, POMC, adrenocorticotrophic hormone (ACTH), alpha-melanocyte-stimulating hormone (MSH), beta-endorphin and orexin-A in selected hypothalamic areas of long day (LD, 16:8 h light:dark), short day (SD, 8:16 h light:dark) and natural-day (ND, photoperiod depending on time of the year) acclimated Siberian hamsters. The gene expression of PC2 was significantly higher within the arcuate nucleus (ARC, P < 0.01) in SD and in ND (versus LD), and is reflected in the day length profile between October and April in the latter. PC1/3 gene expression in the ARC and lateral hypothalamus was higher in ND but not in SD compared to the respective LD controls. The immunoreactivity of PC1/3 cleaved neuropeptide ACTH in the ARC and PC1/3-colocalised orexin-A in the lateral hypothalamus were not affected by photoperiod changes. However, increased levels of PC2 mRNA and protein were associated with higher abundance of the mature neuropeptides alpha-MSH and beta-endorphin (P < 0.01) in SD. This study provides a possible explanation for previous paradoxical findings showing lower food intake in SD associated with decreased POMC mRNA levels. Our results suggest that a major part of neuroendocrine body weight control in seasonal adaptation may be effected by post-translational processing mediated by the prohormone convertases PC1/3 and PC2, in addition to regulation of gene expression of neuropeptide precursors.

Adaptation, Physiological↗

PubMed2005

Do serological tissue turnover markers represent callus formation during fracture healing?

Serological parameters of bone and fibrous tissue turnover were demonstrated to monitor the course of fracture healing. The aim of this study was to evaluate the correlation between the serological parameter levels during fracture healing and callus development in a standardised ovine model of fracture healing. Two years old female sheep received a standardised 3 mm tibial bone defect stabilised by an external fixator. The serological levels of the C-terminal propeptide of procollagen type I (PICP), bone specific alkaline phosphatase (bALP), total alkaline phosphatase (tALP), osteocalcin, tartrate-resistant acid phosphatase (TRAP), calcium, phosphate and the N-terminal peptide of procollagen type III (PIIINP) were observed over a 9-week healing period. The course of fracture healing was monitored radiographically, and the callus composition was evaluated histologically at 2, 3, 6 and 9 weeks post-surgery. The serological results were compared with an untreated control group. Additionally, the maximum values during healing were compared with juvenile values to gauge the level of the serological response. The histological and radiographical results demonstrated callus formation without complications. All serological parameters showed broad inter-individual variations, and the response to the standardised fracture scenario was strongly individual. Maximum values during fracture healing did not reach the juvenile levels. The fractured as well as the control animals showed significant changes in the parameter levels. No correlations were observed between the histological course of healing and the course of bone formation markers whilst the TRAP level was reduced during bony callus formation. The PIIINP level increased when the amount of soft callus tissue decreased during healing. The observed bone formation markers were not suitable as general markers to detect the course of fracture healing, whilst PIIINP was able to reflect soft callus degradation.

Acid Phosphatase↗

PubMed2005

Adaptive mechanisms during food restriction in Acomys russatus: the use of torpor for desert survival.

The golden spiny mouse (Acomys russatus) is an omnivorous desert rodent that does not store food, but can store large amounts of body fat. Thus, it provides a good animal model to study physiological and behavioural adaptations to changes in food availability. The aim of this study was to investigate the time course of metabolic and behavioural responses to prolonged food restriction. Spiny mice were kept at an ambient temperature of 27 degrees C and for 3 weeks their food was reduced individually to 30% of their previous ad libitum food intake. When fed ad libitum, their average metabolic rate was 82.77+/-3.72 ml O(2) h(-1) during the photophase and 111.19+/-4.30 ml O(2) h(-1) during the scotophase. During food restriction they displayed episodes of daily torpor when the minimal metabolic rate gradually decreased to 16.07+/-1.07 ml O(2) h(-1), i.e. a metabolic rate depression of approximately 83%. During the hypometabolic bouts the minimum average body temperature T(b), decreased gradually from 32.6+/-0.1 degrees C to 29.0+/-0.4 degrees C, with increasing duration of consecutive bouts. In parallel, the animals increased their activity during the remaining daytime. Torpor as well as hyperactivity was suppressed immediately by refeeding. Thus golden spiny mice used two simultaneous strategies to adapt to shortened food supply, namely energysaving torpor during their resting period and an increase in locomotor activity pattern during their activity period.

Activity Cycles↗

PubMed2003

Hyperactivity in patients with anorexia nervosa and in semistarved rats: evidence for a pivotal role of hypoleptinemia.

Patients with anorexia nervosa (AN) often show normal to elevated physical activity levels despite severe weight loss and emaciation. This is seemingly in contrast to the loss of energy and fatigue characteristic of other starvation states associated with weight loss. Despite the fact that historical accounts and clinical case studies of AN have regularly commented on the elevated activity levels, the behavior has become only recently the subject of systematic study. Because rodents and other species increase their activity upon food restriction leading to weight loss when given access to an activity wheel--a phenomenon referred to as activity-based anorexia or semi-starvation-induced hyperactivity (SIH)-it has been proposed that the hyperactivity in AN patients may reflect the mobilization of phylogenetically old pathways in individuals predisposed to AN. Exogeneous application of leptin in this animal model of AN has recently been shown to suppress completely the development of SIH. Hypoleptinemia, as a result of the food restriction, may represent the initial trigger for the increased activity levels in AN patients and in food-restricted rats. In the first and second parts of our review, we will summarize the relevant findings pertaining to hyperactivity in AN patients and in the rat model, respectively. We conclude with a synopsis and implications for future research.

Animals↗

PubMed2003

Hormonal and behavioural changes during the mating season and pregnancy in Alpine marmots (Marmota marmota).

Under natural and artificial conditions, Alpine marmots (Marmota marmota) are true hibernators with a single breeding season starting immediately upon emergence from hibernation. Over three mating and breeding seasons, hormonal and mating patterns of colony-housed reproductive female marmots were investigated after exit from hibernation. Blood samples were taken for progesterone, oestrogen and relaxin assays with parallel ultrasound investigations. Copulations were observed from the first day after exit from hibernation until the end of pregnancy and reached a maximum number on day 37 before parturition. Mating behaviour was observed between the dominant animals as well as between dominant and subdominant group members. In the first week after exit from hibernation, plasma progesterone was detected in half of the animals. During the third week, progesterone concentrations were significantly higher in pregnant than in non-pregnant animals or animals that had aborted. Immediately after emerging from hibernation, all successfully mated females showed higher serum relaxin values than non-successfully mated animals and this increase in relaxin concentration lasted until the end of pregnancy. The total concentration of oestrogen did not differ between pregnant and non-pregnant animals. The results of this study indicate that progesterone and relaxin might be useful indicators of early pregnancy in Alpine marmots.

Animals↗

PubMed2001

Implicit and explicit memory after focal thalamic lesions.

BACKGROUND: Lesions of the thalamus interfere with cognitive functions mainly in the area of declarative learning and memory. Little is known about the role the thalamus plays in implicit learning. OBJECTIVE: To study explicit and implicit learning and memory in subjects with thalamic lesions and to analyze the influence of lesion characteristics on cognitive performance. METHODS: The authors studied the performance of 15 subjects with focal thalamic infarction or hemorrhage on a comprehensive neuropsychological test battery focusing on tests of explicit memory and learning of a nondeclarative motor skill. Subjects with thalamic lesions were compared to 15 healthy matched control subjects and to a clinical control group of 22 subjects who had sustained basal ganglia lesions. RESULTS: Subjects with thalamic lesions showed well-preserved intellectual and executive functions but demonstrated deficits on measures of attention and psychomotor speed, explicit memory, and implicit visuomotor sequence learning. Lesion size in the thalamus was clearly related to subjects' long-term explicit memory performance. However, few of the neuropsychological deficits found seemed specific to the long-term neuropsychological outcome of focal thalamic infarctions. Subjects with lesions in the basal ganglia demonstrated similar deficits. CONCLUSIONS: Focal subcortical lesions in the thalamus and the basal ganglia lead to a similar profile of neuropsychological deficits. Lesions in the thalamus not only affect declarative memory but also interfere with nondeclarative motor skill learning.

Adult↗

PubMed2000

Leptin suppresses semi-starvation induced hyperactivity in rats: implications for anorexia nervosa.

Semi-starvation induced hyperactivity (SIH) occurs in rodents upon caloric restriction. We hypothesized that SIH is triggered by the decline in leptin secretion associated with food restriction. To test this hypothesis, rats, which had established a stable level of activity, were treated with leptin or vehicle via implanted minipumps concomitantly to initiation of food restriction for 7 days. In a second experiment treatment was initiated after SIH had already set in. In contrast to the vehicle-treated rats, which increased their baseline activity level by 300%, the development of SIH was suppressed by leptin. Furthermore, leptin was able to stop SIH, after it had set in. These results underscore the assumed major role of leptin in the adaptation to semi-starvation. Because SIH has been viewed as a model for anorexia nervosa, we also assessed subjective ratings of motor restlessness in 30 patients with this eating disorder in the emaciated state associated with hypoleptinemia and after increments in leptin secretion brought upon by therapeutically induced weight gain. Hypoleptinemic patients ranked their motor restlessness higher than upon attainment of their maximal leptin level during inpatient treatment. Thus, hypoleptinemia might also contribute to the hyperactivity frequently associated with anorexia nervosa.

Animals↗

PubMed1998

Obsessive-compulsive disorder and ventromedial frontal lesions: clinical and neuropsychological findings.

OBJECTIVE: The authors sought to determine the long-term outcome of subjects with severe and refractory obsessive-compulsive disorder (OCD) who had undergone ventromedial frontal leukotomy during the 1970s. Special emphasis was given to the analysis of specific lesion sites. METHOD: Sixteen OCD subjects who had undergone ventromedial frontal leukotomy were evaluated clinically and neuropsychologically and compared to seven well comparison OCD subjects without leukotomy. The 16 leukotomized subjects were divided into three groups according to the main lesion sites as determined by current magnetic resonance imaging scans. RESULTS: The leukotomized OCD subjects showed significant improvement of obsessive-compulsive symptoms; subjects with frontostriatal lesions tended to have improved most. The subjects with combined diagnoses of OCD and obsessive personality disorder (N = 3) had improved significantly less. Of 11 subjects with lesions of the ventral striatum, eight had developed substance dependence postoperatively. Intellectual functions were largely preserved in subjects with ventromedial frontal lesions only or frontostriatal lesions. However, all subjects showed subnormal performance on the Wisconsin Card Sorting Test. Subjects with lesions of the dorsolateral frontal convexity also showed memory problems, attentional slowing, and lower performance IQ. CONCLUSIONS: Restricted ventromedial frontal leukotomy should be discussed as a last-resort treatment for severe and refractory OCD but not obsessive personality disorder. Lesions of the ventral striatum were significantly related to the occurrence of substance dependence, suggesting a role of this area in human addictive behavior.

Behavior, Addictive↗

PubMed1997

[Climatic condition and airborne microorganisms in wild cat housing].

The aim of the present study was to obtain information to improve the environmental conditions in enclosures for cats of prey. There was a large variation in indoor temperature, relative humidity, concentration of airborne ammonia and microorganisms during the year. The ascertained concentrations of airborne microorganisms distinguished between the different housing systems and ranged between 7177 and 15,835 KBE/m3. The concentration correlated negatively with the temperature outside of the buildings, while the amount of each compound, especially the gram positive cocci and rods, was influenced by the microclimate of the stables. The gram negative germs covered only 4.5 to 7.5%. Therefore the gram positive microorganisms were predominant. Part of the primary pathogen germs was low and amounted below 1%. There was now risks for visitors to get an infectious disease caused by the zoo animals.

Air Microbiology↗

PubMed1988

Comparison of tactile preferences in children with and without cerebral palsy.

Fifteen normal preschool children and 15 preschool children with cerebral palsy were presented with 10 pairs of objects and asked to identify their preference for one of the objects in each of the pairs. Five objects of different textures were used. The children only handled the objects; they did not view them during testing. The children with cerebral palsy chose hard objects significantly more often than they chose soft objects; the normal children had no significant choice preferences. Eleven of the children with cerebral palsy had choice patterns significantly different from those of the normal children. The apparent preference of the children with cerebral palsy for hard objects and their avoidance of soft objects suggests that they may have decreased tactile awareness and need the greater proprioceptive input that hard objects provide. The findings of this study indicate that preschool children with cerebral palsy may be at high risk for somatosensory disorders, which could markedly affect their hand function.

Cerebral Palsy↗