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Biomedical subjects

P Gerard

Publications and source records attributed to P Gerard.

At least 37 records · Page 2Linked to original sources
PubMed1998

Reference values of body composition obtained by dual energy X-ray absorptiometry in preterm and term neonates.

BACKGROUND: As previously reported, dual-energy x-ray absorptiometry provides reliable and accurate values for bone mineralization in piglets and infants, but overestimates fat content in small infants. The purpose of the current study was to determine an appropriate equation of correction for fat mass measurement and to establish reference values of body composition of preterm and term neonates. METHODS: Fat mass and chemical whole-body fat content were evaluated by dual-energy x-ray absorptiometry in eight piglets with a body weight between 1408 and 5151 g. The results were combined with previous data obtained in 13 piglets, and two correction equations were determined according to fat mass content. Close to birth, 106 healthy appropriate-for-gestational-age preterm and term infants were scanned by dual-energy x-ray absorptiometry to determine bone mineral content, bone area, and fat mass. Fat mass content determined by dual-energy x-ray absorptiometry was corrected using the equations obtained in piglets after which lean body mass was recalculated. RESULTS: Multivariate analysis showed that dual-energy x-ray absorptiometry body weight was the best predictor of bone mineral content (r2 = 0.94), bone area (r2 = 0.95), lean body mass (r2 = 0.98), and fat mass (r2 = 0.84). Gender was an additional significant independent variable for fat mass and lean body mass. Body weight related curves of percentiles for bone mineral content, bone area, fat mass, and lean body mass, were constructed. In vivo dual-energy x-ray absorptiometry values of fat mass and calcium content estimated from bone mineral content were in accordance with previously reported whole-body carcass reference values in preterm and term neonates. CONCLUSION: Normative data of dual-energy x-ray absorptiometry body composition for healthy preterm and term infants are provided and can therefore be used in research and in clinical practice.

Absorptiometry, Photon↗
PubMed1998

Correction of pressure waveforms recorded by fluid-filled catheter recording systems: a new method using a transfer equation.

BACKGROUND: Pressure measuring systems using fluid-filled catheters can result in the recording of distorted pressure waveforms. It results in phase delay, overestimation of systolic and, to a lesser extent, of diastolic pressure. We designed and evaluated a method to correct this pressure waveform distortion using an appropriate transfer equation obtained from the dynamic response of the fluid-filled catheter. This transfer equation is based on the principle that a fluid-filled catheter recording system is considered as an underdamped dynamic system fully characterized by its natural frequency (omega n) and damping ratio (zeta). METHODS: Pressure waveforms, simultaneously recorded in vitro or in vivo by a fluid-filled catheter (Pc) and a micromanometer-tipped catheter (Pref), were used to validate the method. Dynamic response of the catheter used was obtained from a fastflush test. The corrected signal (Ppred) was obtained using omega n, zeta and the following transfer equation: d2Pc/dt2 + 2 omega n zeta dPc/dt + omega n 2Pc = C Ppred (t) After correction of Pc, Ppred was compared, using a linear regression, with Pref taken as reference. RESULTS: Our results showed that Ppred was fitted to Pref with excellent coefficient correlation (0.99). The mean error and the standard error of estimate were respectively -1.16 mmHg and 1.4 mmHg. CONCLUSION: This new method can convert the distorted pressure waveforms transmitted by any fluid-filled catheters into high-fidelity signals. It suppresses the phase delay and the over-estimation of systolic pressure induced by fluid-filled catheters.

Animals↗
PubMed1998

Anterior/posterior influences on neural crest-derived pigment cell differentiation.

The neural crest of vertebrate embryos has been used to elucidate steps involved in early embryonic cellular processes such as differentiation and migration. Neural crest cells form a ridge along the dorsal midline and subsequently they migrate throughout the embryo and differentiate into a wide variety of cell types. Intrinsic factors and environmental cues distributed along the neural tube, along the migratory pathways, and/or at the location of arrest influence the fate of neural crest cells. Although premigratory cells of the cranial and trunk neural crest exhibit differences in their differentiation potentials, premigratory trunk neural crest cells are generally assumed to have equivalent developmental potentials. Axolotl neural crest cells from different regions of origin, different stages of development, and challenged with different culture media have been analyzed for differentiation preferences pertaining to the pigment cell lineages. We report region-dependent differentiation of chromatophores from trunk neural crest at two developmental stages. Also, dosage with guanosine produces region-specific influences on the production of xanthophores from wild-type embryos. Our results support the hypothesis that spatial and temporal differences among premigratory trunk neural crest cells found along the anteroposterior axis influence developmental potentials and diminish the equivalency of axolotl neural crest cells.

Ambystoma↗
PubMed1997

Biomechanical characteristics of unconditioned and conditioned latissimus dorsi muscles used for cardiocirculatory assistance.

An understanding of the biomechanical characteristics of striated skeletal muscles involved in cardiocirculatory assistance is a prerequisite to assess their efficacy and to evaluate their haemodynamic benefits. Six goats had their latissimus dorsi muscles evaluated by isometric strain gauge testing. Total tension, and both active and passive force development at different preloads were measured. The relationship between muscle impedance and starting length was also studied. Four additional muscles were submitted to isometric and isotonic strain gauge testing after 3 months of chronic electrical stimulation (Broussais Hospital protocol) with the contralateral muscle serving as a control. In isometric testing, both conditioned and unconditioned goat latissimus dorsi displayed a Frank-Starling length-tension curve, and a linear relationship between muscle impedance and starting length was found. Chronic stimulation preserved muscle mass and isometric force. Transformed muscles showed a mean 59% reduction of maximal shortening velocity; means (s.d.) residual shortening velocity at maximal work and power output was 0.17(0.07) m/s. The work and power output were both reduced 65% after stimulation, and the residual maximal power at optimal preload varied from approximately 7.7 and 9.6 W/kg. It is concluded that, following the Broussais protocol, the goat latissimus dorsi muscle retained mass and most of its isometric force-generating capacity, but lost significant work and power potential. The residual power output did not, however, preclude the possibility of a significant cardiocirculatory contribution, providing that the conditions for optimal energy transduction are adequately delineated.

Animals↗
PubMed1996

Crohn's disease and vitamin B12 metabolism.

The concentrations of vitamin B12, its analogs, and the haptocorrin and transcobalamin carriers in 21 patients suffering from Crohn's disease and a group of controls (20 adults) were measured. There were no significant differences in the mean values for vitamin B12, total corrinoids (vitamin B12 + analogs), or vitamin B12 or total corrinoids bound to haptocorrin or transcobalamin of the Crohn's and control patients. There was a significant increase in the binding capacity of transcobalamin in the Crohn's patients compared to the controls (P < 0.001), but there was no difference in the binding capacities of haptocorrin. The serum concentrations of the markers of vitamin B12 status, homocysteine and methylmalonic acid, showed an increase (P < 0.01) in homocysteine in the Crohn's disease patients, but no change in methylmalonic acid. As the hyperhomocysteinemia was associated with normal folate concentrations, there may have been a defect in the activation of the enzyme due to altered intracellular vitamin B12 status.

Adult↗
PubMed1996

Properties of Allyl Alcohol-Resistant Mutants of Clostridium butyricum Grown on Glycerol.

Mutants of Clostridium butyricum E5 exhibiting resistance to allyl alcohol which produced the same quantities of 1,3-propanediol as the wild-type strain but more acetate than butyrate were isolated. The acetate-butyrate formation plays a major function in the regulation of the internal redox balance. Allyl alcohol resistance can be attributed not to the loss of 1,3-propanediol dehydrogenase but to a shift in the reductive properties of the enzyme. The data support the view that cellular regulation is modified to avoid intracellular accumulation of 3-hydroxypropionaldehyde.

Journal Article↗
PubMed1995

Staphylococcus periprostatic abscess: an unusual cause of acute urinary retention.

Prostatic abscess has occasionally been known to present with urinary retention. We report an unusual case of a Staphylococcus aureus periprostatic abscess causing acute urinary retention. Diagnosis was made by transrectal sonogram and computed tomography scan, and the patient was treated successfully with intravenous antibiotics, perineal exploration, and drainage.

Abscess↗
PubMed1995

Specificity and sensitivity of temporalis ES2 measurements in the diagnosis of chronic primary headaches.

We have evaluated the specificity and sensitivity of temporalis ES2 measurements for the diagnosis of primary headaches. Ninety-four outpatients diagnosed according to IHS criteria were prospectively included: 25 had chronic tension-type headache (code 2.2.), 15 episodic tension-type headache (code 2.1.), 20 migraine without aura (code 1.1.) and 34 chronic daily headaches with daily analgesics/ergotamine abuse (code 8.2.). In chronic tension-type, the sensitivity of the ES2 test was 84% at the 0.1 and the 0.5 Hz, but only 56% at the 2Hz stimulation rates. Its specificity was 100% at 0.1Hz, 90% at 0.5Hz and 95% at 2Hz compared to migraine; positive predictive values were at similar levels. Sensitivity of ES2 at 0.1 Hz was 67% in episodic tension-type headache, but its positive predictive value versus migraine was excellent. Comparing chronic tension-type headache and analgesic abusers, the specificity and positive predictive value of the ES2 test for diagnosing chronic tension-type headache were less satisfactory (60%) while the negative predictive values, however, remained good (83% at 0.1Hz). The results confirm that the temporalis ES2 test has a higher diagnostic sensitivity in chronic and episodic tension-type headache, but that it has a high negative predictive value for both types of tension-type headache compared to other primary headaches. For diagnostic purposes, the 0.1Hz stimulation rate seems optimal. The 2Hz stimulation rate is the least sensitive, although it may induce total disappearance of ES2 in up to 40% of patients. ES2 is of limited usefulness for separating chronic tension-type headache and chronic drug-abuse headache, possibly because the latter group comprises both tension-type headache and migraine patients.

Chronic Disease↗
PubMed1994

Modulation of temporalis muscle exteroceptive suppression by limb stimuli in normal man.

The effects of noxious and non-noxious limb stimulations on the second exteroceptive suppression of voluntary temporalis muscle activity (ES2) were studied in healthy human volunteers. Duration of temporalis ES2 was measured on averaged rectified responses obtained after stimulating the labial commissure at an intensity of 25 mA. Single peripheral electrical stimuli applied over nerve trunks or over the skin before the labial stimulus decreased ES2 duration. This effect was most pronounced after cutaneous stimuli, especially of the index finger, and it was not observed when the conditioning stimulus was a 10 second, high frequency train. For stimulation at the index finger, temporalis ES2 inhibition progressively increased with intensity from 10 mA to 40 mA; it was maximal for an interstimulus interval between 50 and 140 ms. After naloxone (0.4 mg or 4 mg, i.v.) there was a partial reversal of the index-induced ES2 depression, but this effect was not significant. Immersion of one hand in water heated at 47 degrees C produced a short-lasting ES2 reduction. These results are comparable, though not similar, to the inhibition of the digastric reflex (or jaw opening reflex) observed in animals after limb stimuli and to the depression of the spinal flexion reflex reported in man after heterotopic peripheral stimuli. Although peripheral stimuli were able by themselves to suppress temporalis EMG activity in some subjects, it is likely that they reduce labial-induced ES2 via activation of brainstem structures, such as periaqueductal gray matter or raphe magnus nucleus, which are thought to inhibit the medullary inhibitory interneurons mediating ES2.

Electric Stimulation↗
PubMed1994

[Restoration of opposition using the extensor pollicis longus. Apropos of 8 cases reviewed after 11 years].

Moutet and coll. had studied in 1986 a series of 16 cases of restoration of thumb opposition by extensor pollicis longus transfer onto abductor pollicis brevis through the inter osseous membrane. Eleven years follow-up revision of 8 of those 16 patients was performed by the authors. Indication of transfer was traumatic median nerve isolated palsy or associated to ulnar nerve palsy. Objective and subjective analysed parameters allowed to check the evolution of the transfer and to justify its indications. No transfer retraction has been noted in long term follow-up. The side effects of its removal (thumb retropulsion and MP extension defects) have minimum functional consequences. The opposition has been restored at the time of thenarians recovery and as well, each time the palsy was going on. In the cases where the thenarians recovered, the transfer became an antepulsion supply. The authors suggest to perform an opposition transfer, each time it is technically possible, in severe median nerve lesions, at the time of emergency operation.

Adolescent↗
PubMed1994

[A new titanium-carbon finger joint implant. Apropos of 15 initial cases].

Arthroplasty of the MP and PIP joint remains a therapeutic challenge for the hand surgeon. The poor results of the currently available implants are due to their mechanical conception (non strained) or their material (silicone causing instability, ruptures and silicone synovitis). The authors present the preliminary results of a new digital articular implant (IAD). It is a strained implant with a rigid hinge allowing 105 degrees of range of movement (0 degree to 105 degrees). Three sizes are available and very soon four. The intramedullary stems are in titanium alloy (TA6V) and the gliding surfaces in pyrolytic carbon. This association allows solidity, endurance, excellent gliding and no wear debris. 15 implants were evaluated (13 PIP and 2 MP joints) with a follow-up from 4 to 1 year. A painless range of motion were restored in 11 cases and 4 articulations were only lightly painful during motion requiring strength and at the end of the movement. The gain of the range of movement was 50 degrees always in a useful sector. The grasp was 60% better in post than in pre operative conditions. No infection was found. It is only the beginning of this implant but the indications seem to be good for all the articular destructions of the digital joints what ever was the aetiology (traumatic, infection or rheumatoid arthritis).

Adult↗
PubMed1994

[A proposal for a functional evaluation record for the hand].

Proposition of a new evaluation method included an analytic cotation, a functional cotation, and a cosmetic cotation. Use is speeded by the suppression of all kind of measure instrument and facilited by pictures. Application to the corporal damage evaluation.

Disability Evaluation↗
PubMed1994

[A rare renal tumor: cavernous hemangioma. Apropos of a case].

The authors report a case of cavernous hemangioma of the kidney, a rare benign tumor. The interest of this case is probably to be the only one reported with MRI: an high signal intensity T2 in weight sequence could represent in the future a good information for the diagnosis. Endoscopic methods are useful for the diagnosis, but cannot be used for therapy. The treatment is surgical. Selective embolisation could be a good alternative in the future.

Adult↗
PubMed1993

[Subcutaneous rupture of long finger flexor pulleys in rock climbers. 12 case reports].

Rock climbing generates a new type of microtraumatic, stress pathology involving all of the osteoarticular chain of the upper limb. The hand is the site of specific lesions: pulley ruptures (A2) are the most frequent. 12 top-level climbers (7a and above) were reviewed out of a series of 23 cases. In 7 cases, the ring finger was affected and in 5 cases the middle finger was affected. All cases were treated by rest and protection of the A22 pulley with an external rigid ring. Progressive return of climbing was allowed after the 45th day. The effects on the level of performance, residual pain and its consequences, and on associated lesions of the upper limb were investigated. 8/12 patients regained at least their previous level of performance and 6/12 no longer experienced any pain. 5/12 patients experienced minor pain which did not affect their level of performance. One patient had to stop top-level climbing because of persistent pain. Protection of the pulley, possibly combined with syndactylisation and complete rest, not only from sports activities, for at least 45 days are the best way of ensuring a satisfactory functional result in these particularly demanding subjects. Physiotherapy and non-steroidal anti-inflammatory treatment can also be combined.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

[Protected early mobilization using Levame's device after primary repair of the extensor tendons of the hand. Apropos of a series of 88 cases].

Seventy patients with 88 lesions of the hand extensor apparatus were treated by primary repair followed by post-operative mobilisation with a dynamic steel blade splint (Levame). Results were good or very good in 97.7% of cases and moderate in 2.3% of cases for this series of simple lesions from zones 3 to 6. Prognostic factors influencing final result and wrist position during splint are discussed, the authors leave the wrist free for lesions in zone 3 and 4. Early mobilisation is the best treatment for tendinous lesions and a review of the literature confirms the validity of the author's choice. In spite of its biomechanical deficiencies, this simple technique may be used for non-disciplined patients and by non-specialized physiotherapists. For simple lesions of extensor tendons, the Levame splint may be considered as a real dynamic protective splint.

Adolescent↗
PubMed1992

Facilitation of responses to motor cortex stimulation: effects of isometric voluntary contraction.

In 7 normal subjects we compared the facilitatory effect of isometric contraction of the tibialis anterior on the size of electromyographic responses evoked in this muscle by electric stimuli applied over the cervical column and by electric and magnetic percutaneous stimulation of the motor cortex. No significant difference was found between the degrees of facilitation of the responses to any of the stimuli. Using collision techniques, we also showed that the pyramidal fibers activated by spinal and cortical stimuli are the same. Facilitation induced by isometric contraction (20% maximum) was of similar or greater magnitude than that found with constant vibration of the tendon of the target muscle. In cases where vibration and contraction had equal facilitatory effects, there was no further facilitation of the responses when both conditions were applied together. These findings indicate that the facilitatory effect of isometric contraction of the target muscle essentially originates at a spinal level rather than in the motor cortex.

Adult↗
PubMed1992

High rate of multiple genital HPV infections detected by DNA hybridization.

Cervical smears collected from 450 patients involved in a clinical follow-up of cervical human papillomaviruses (HPV) infections were screened for the presence of HPV 6b, 11, 16, and 18 DNA by both dot blot and southern blot hybridization methods. Using very high stringency hybridization assays, the four HPV types could be easily distinguished by dot blotting. After a preliminary clinical sorting, 42.9% of the samples were found to be HPV-positive. Among the samples infected by a single HPV, type 16 was the most frequent (25.4% of the positive samples) followed by 6b (19.7%), 11 (8.3%), and 18 (7.2%). Double or even multiple infections by the different HPV types were detected at a very high rate (39.4% of the positive samples).

Belgium↗