Selected scientific publications on diving medicine and physiology.
2011 Apr 4
The normobaric oxygen paradox: a novel way to administer oxygen as an adjuvant treatment for cancer?
De Bels D, Corazza F, Germonpré P, Balestra C.
The "normobaric oxygen paradox" is a dual mechanism by which oxygen regulates the expression of the Hypoxia Inducible Factor 1 alpha (HIF-1α). The HIF-1α-depending gene regulation is responsible for many different genetic expressions including EPO and VEGF that are usually expressed in parallel. First, VEGF under-expression could decrease tumor angiogenesis leading to a decrease in tumor growth or even apoptosis of cancer cells. Second, induction of EPO-expression can provide cytoprotection. Altogether, this could be deleterious for cancer cells while helping non-malignant cells (at least neural and cardiac) cells to be protected from the side effects of chemotherapy. Eventually, HIF induction could boost immune response by inflammatory cells, increasing their antitumor activity.
Respiratory rate can be modulated by long-loop muscular reflexes, a possible factor in involuntary cessation of apnea
Balestra C, Levenez M, Lafère P, Dachy B, Ezquer M, Germonpré P.
INTRODUCTION: The main limiting factors determining apnea time are generally considered to be related to blood and cerebrospinal fluid chemistry. Several physiological (adaptive) mechanisms and some psychologic parameters, such as motivation, are also known to increase apnea time.
AIM:We wished to study the link between peripheral muscle fatigue, the concomitant alteration of long latency (transcortical) reflexes and respiratory control.
METHODS: Fatigue was induced in a small hand muscle (abductor pollicis brevis) (n = 11). This muscle is sufficiently small that its fatigue and the resulting production of metabolites are unlikely to alter whole-blood biochemistry. The Hoffmann reflex, an involuntary reaction to electrical stimulation of muscle afferent sensory fibreswas studied, as was the long latency reflex (LLR) using the Dueschl method in which electrical stimulation is superimposed on a slight voluntary contraction, Different fatiguing protocols were performed, and respiratory rate continuously recorded.
Analysis of clinical outcomes of linear vs. deep stop decompression from 3.5 to 6 atmospheres absolute (350 - 600 kpa) in awake rats
Cronjé FJ, Meintjes WA, Bennett PB, Fitchat S, Marroni A, Hyldegaard O.
ecreational divers are introducing "deep stops" at half the depth (HD-DS) to reduce the risk of spinal DCS with only Doppler evidence to support it. Therefore this research was designed to show the effect of an HD-DS on spinal DCS manifestations by evaluating whether: (1) air diving-induced spinal DCS could be produced in awake, freely moving rats at 3.5-6.0 atm abs (350-600 kPa); and (2) whether the introduction of an HD-DS reduced spinal DCS in such a model. Fifty-one female, Wistar rats (221 to 450 g) underwent one-hour compression at 350 to 600 kPa with seven minutes of decompression with/without a five-minute DS (HD-DS / No-DS). Animals were observed for three hours. Outcomes were classified as: (1) asymptomatic; (2) breathing difficulties; (3) paralysis/weakness; (4) immobility; or (5) death. Eight animals, exposed to 385 kPa air breathing for 60 minutes followed by a three-staged decompression of 7.5 minutes, remained asymptomatic. The profile is known to produce spinal DCS in anesthetized rats. Eleven animals were then used to determine the threshold for DCS: 500 kPa. A total of 14 animals were compressed to 550 kPa (Group 1). Group 1-A (n = 8) No-DS; Group 1-B (n = 6) HD-DS; 18 were compressed to 600 kPa (Group 2). Group 2-A (n = 8) No-DS; Group 2-B (n = 10) HD-DS.
A Neuro-fuzzy Approach of Bubble Recognition in Cardiac Video Processing
Chefiri H., Zain J.M.m El-Qawasmeh E., Parlak I.B., Egi S.M., Ademoglu A., Balestra C., Germonpre P., Marroni A., Aydin S.
2D echocardiography which is the golden standard in clinics becomes the new trend of analysis in diving via its high advantages in portability for diagnosis. By the way, the major weakness of this system is non-integrated analysis platform for bubble recognition. In this study, we developed a full automatic method to recognize bubbles in videos. Gabor Wavelet based neural networks are commonly used in face recognition and biometrics. We adopted a similar approach to overcome recognition problem by training our system through real bubble morphologies. Our method does not require a segmentation step which is almost crucial in several studies. Our correct detection rate varies between 82.7-94.3%. After the detection, we classified our findings on ventricles and atria using fuzzy k-means algorithm. Bubbles are clustered in three different subjects with 84.3-93.7% accuracy rates. We suggest that this routine would be useful in longitudinal analysis and subjects with congenital risk factors
There is a limited understanding of the normal function of the pterygoïdeus proprius muscle and the role that this muscle may have in temporomandibular disorders. Despite a well-described anatomical in-vitro approach to this muscle, there are still difficulties in investigating the fossa pterygopalatina. This study reveals an alternative in-vivo approach by magnetic resonance imaging to visualise the muscle in the fossa pterygopalatina on 78 head halves, describe the connections with the musculus temporalis and pterygoïdeus lateralis as well as report the incidence without dealing with the known inconveniences of the dissection approach. The results show an incidence of 12.82% for the musculus pterygoïdeus proprius equally divided between both genders. Two different types of bridging between the musculus temporalis and musculus pterygoïdeus lateralis were also found: (i) 'O' shape (6.41%) and (ii) 'Y' shape (6.41%). This study suggests the use of magnetic resonance imaging to investigate the different connections between vascular and muscular structures in the fossa pterygopalatina. Further research with this approach to link the appearance of the muscle with neurovascular entrapment syndromes is warranted.
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