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Biomedical subjects

J Benoit

Publications and source records attributed to J Benoit.

At least 19 recordsLinked to original sources
PubMed1992

Comparative effects of luminance and scatter on the pattern visual evoked potential and eye-hand reaction time.

We investigated the effect of reduced luminance and increased scatter on the pattern visual evoked potential and eye-hand reaction time evoked to a check size of 0.5 degrees in 10 normal subjects. Data analysis indicated that a reduction in luminance as well as an increase in scatter caused a statistically significant increase in the peak time of the pattern visual evoked potential P100 wave. The reaction time, however, was not significantly affected by the initial 0.9-log unit attenuation of the stimulus luminance or the 0.3 scatter filter. Further attenuation of luminance or increase of scatter also yielded statistically significant increases. Our results suggest that the reaction time is less affected by a reduction in luminance or an increase in scatter of a 0.5 degrees stimulus than the pattern visual evoked potential is and therefore represents a more reliable test to assess visual function, especially in the presence of medial opacities, which are known to reduce luminance and produce scatter.

Adolescent↗
PubMed1992

[Lesions of the ligaments associated with distal fractures of the radius. 58 intraoperative arthrographies].

Intracarpal ligamentous tears and fractures of the radius often have a similar mechanism. For instance, no prospective studies have defined the real incidence of such associations, which are not antagonistic. The authors performed a systematic operative wrist arthrogram during distal radius fractures in a group of 58 patients with a mean age less than 50 years. Such a population was at low risk of degenerative ligamentous tears. Triangular fibrocartilage complex was torn in two-thirds of all types fractures. Extra-articular radius fractures were associated with an intracarpal ligamentous tear in 25% and always a luno-triquetral lesion type. In contrast, intra-articular and radius styloid fractures were frequently associated with a scapho-lunate lesion.

Adolescent↗
PubMed1992

[Osteochondritis dissecans of the acetabulum. Apropos of a case].

Osteochondritis dissecans acetabuli is a rare affection. The observation presented is one of a 23 year old man, who presented hip blockages in external flexion rotation. X-ray only allowed to find a sequestrum in the acetabulum by tomography-Arthroscanner confirmed the osteochondritis without cartilage rupture. Arthroscopy eliminated a cartilage lesion and directed towards a cavity filled by spongious bone through an extra articular approach.

Acetabulum↗
PubMed1992

[Arthroscopic internal meniscectomy in patients over 55 years of age. Results over more than 4 years].

Fifty-one meniscectomies by arthroscopy were realised on patients of more than 55 years of age between 1981 and 1986. Twenty-four patients were reviewed after at least 4 years of follow up, 12 of them after a 7.5 years follow up. 21 results were noted as functionally very good or good, 3 were poor. The radiological analysis of femoro-tibial compartments in comparison with the non operative side showed a clear pejorative difference in one case, moderate in 5 without incriminating the morphological type. If the quality of result does'nt correlate with age, it was'nt the same for the type of lesion seen during arthroscopy, the best results after arthroscopic meniscectomies were seen in traumatic lesions occurring on normal menisci or on degenerative ones. The authors concluded that medial meniscectomy in patients older than 55 years is justified in precise indications: a known traumatism or also acute medial pain, or speedy with normal or subnormal X-ray and after a positive arthrography.

Aged↗
PubMed1992

[Bipolar endoprosthesis in fractures of the femoral neck. Apropos of 201 cases, 116 after a 6-year follow-up].

We report our experience with 201 SEM bipolar prostheses used to treat femoral neck fractures in patients with a mean age of 70 years and a mean follow-up of 57 months (median 75 months). Clinical outcome was favorable with 94 per cent satisfactory results (very good and good). Femoral complications requiring reoperation (conversion to total hip replacement) occurred in 2.2 per cent of cases. Among the 163 patients for whom roentgenographic data were available, 5 (3.6 per cent) developed evidence of acetabular wear but remained symptom-free and did not require reoperation. As compared with Moore's prosthesis, the SEM bipolar prosthesis seems to provide substantially better clinical and roentgenographic results. For the treatment of femoral neck fractures, total hip replacement seems to provide results comparable to those reported here but requires a more sophisticated operative technique and carries a greater risk of subsequent dislocation. Two factors prevent the widespread use of the bipolar prosthesis at present: the need for femoral grouting which carries a well-documented risk of hemodynamic complications, and the higher cost of the device.

Adult↗
PubMed1992

[Embolization of the circumflex femoral artery for recurrent hemorrhage after total hip arthroplasty. Apropos of a case].

Reoperation of an haemorrhagic complication after total hip arthroplasty may be not efficacious when, as in the case report, bleeding's origin is not found. The vital prognosis can be quickly set in action and then the arterial embolization be the swift and efficacious solution. The selective arteriography that precedes it allows to locate the bleeding's origin, to estimate gravity of leak and to set indication of embolization. So it is fitting to think of this therapeutic solution that may avoid new operation and new failure.

Aged↗
PubMed1991

Impact of a second insemination on the results of an in vitro fertilization-embryo transfer (IVF-ET) program.

In an attempt to increase the fertilization and pregnancy rates in our program, a second insemination was carried out when the first insemination yielded fewer than two fertilized oocytes. One hundred eighty consecutive patients were studied retrospectively and thirty-four required second insemination, 35% of them by donor semen. Fifty-five and nine-tenths percent of the patients had at least one fertilized oocyte for embryo transfer, but only 21.9% of the oocytes exposed to a second insemination were fertilized. No pregnancy resulted from the transfer of oocytes fertilized by the second insemination. There were no significant correlations between the success of fertilization after a second insemination and the number of oocytes retrieved, the protocol for the induction of superovulation, or the age of the female patient. Considering that the first insemination was done at a variable time after oocyte retrieval to allow oocyte maturation, we expected all oocytes to be mature at the time of first insemination and we considered the possibility of delayed fertilization as negligible since second insemination was done at least 24-30 hr after oocyte retrieval. Even though a second insemination provides further hope for the patient, by yielding additional fertilized oocytes for embryo transfer, its main value is that it may provide additional information about male fertility.

Adult↗
PubMed1991

Temporal relationship between the ERG and geniculate unit activity in rabbit: influence of background luminance.

The comparative analysis of the retinal and lateral geniculate nucleus (LGN) intensity-response function revealed that the timing of the LGN unit response was highly correlated to that of one oscillatory potential (OP2). To examine if this OP2-LGN intensity-response function was retained irrespective of the state of retinal adaptation, we performed simultaneous recordings to the ERG and single-cell unit activity at the geniculate level evoked to a flash of constant energy while the level of background luminence was varied. For a stimulus of 6.7 cd m-2 sec, the shifts in latency induced by increasing the background luminance from 0 to 125 cd m-2 are of 1.17 +/- 0.61 msec for OP2, a value almost identical (P greater than 0.10; n = 36) to the one obtained at the geniculate level (1.11 +/- 0.88 msec). However, when a dimmer flash is used, the latency shifts are not so well correlated. The latter could be partly explained by the threshold nature of the resulting stimulus (i.e. high photopic background combined with a dim flash).

Action Potentials↗
PubMed1991

[Local surgical treatment of anal-perineal lesions in Crohn's disease. Retrospective study of 68 cases].

Sixty eight cases of ano-perineal lesions (APL) were studied. Lesions were classified into primary (19) and secondary (49) after Hughes. The course of primary APL was favourable (15 cases, 78 p. cent) when proximal CD was controlled, with 4 proctectomies being required when the latter was not the case. Suppurative secondary APL (48) were treated surgically either for an acute abscess (22) or for a chronic fistula (low: 14; high: 12). The treatment of fistulas involved: opening in 10 cases (4 recurrences, 5 failures) or slow fistulotomy with elastic in 17 cases (9 recurrences, 4 failures). Genital fistulas (9 cases) were studied separately: 3 recto-vaginal fistulas resulted in a permanent bypass and 6 ano-vulval fistulas healed or were tolerated. When proximal CD was controlled medically, proctological treatment alone resulted in the healing or quiescence of APL in 17/24 cases. In the group of patients undergoing intestinal resection with restoration of continuity, 10/25 recurred, with the appearance of worsening of an APL in 9 of them. Fifteen had no recurrence, with the appearance or worsening of an APL in 3 of them. In total, 13 patients (19 p. cent) underwent proctectomy, including 6 from the outset. Five had a stroma which was left open and 46 (72 p. cent) a functional anus. Local surgical treatment improved the comfort of patients without any increased risk regarding sphincter function, but the long term benefits of the active treatment of chronic fistulas remain to be proven.

Adolescent↗
PubMed1991

[Bone allografts revascularized by autogenous endosseous flap. Experimentation in rats].

The experimentation was based on the analysis of revascularization phenomenons and reossification of cross allografts of Wistar rat femoral diaphysis firstly canalized with an epigastric subcutaneous intramedullar autogenous flap. An endosteal revascularization has been observed in addition to the periosteal one which is usually the sole characteristic of classic allografts. The bone transplant, quickly vascularized after a short period of creeping substitution, had normal histomechanical properties which were never observed without the addition of a vascular pedicule. The use of such cortical allografts seems to be useful in human surgery.

Animals↗
PubMed1991

[Luxation of total hip prosthesis. Mathematic modelization, biomechanical approach].

Two particular aspects of total hip prosthesis dislocations were assessed by a mathematical method. A theoretical analysis of the intra-prosthetic motions, in function of the architectural parameters was presented as well as a biomechanical approach of the dynamic stability of the prosthetic hip during the flexion. It showed then two potential causes of dislocations: malposition dislocations, due to the block-effect of the femoral neck on the acetabular border; the position of the acetabular cup appeared as predominant for a given type of prosthesis too anteversed and/or too vertical, it limited the movement of external rotation at the origin of anterior dislocations; too horizontal and not enough anteversed it obstructed the flexion, especially if there was an association of internal rotation and adduction, the dislocation was then posterior. dislocation by muscular discoaptation. Here, the dislocating forces, during the flexion of the hip, were greater than the coaptation phenomenon which became precarious by the arthroplasty and quantified, in our model, by a multifactorial parameter translating the behaviour of the gluteus medius muscle during flexion.

Biomechanical Phenomena↗
PubMed1991

[Luxation of total hip prosthesis. Statistical validation of a modelization, apropos of 52 cases].

A previous modelization of the Total Hip Dislocation phenomenon enabled us to separate two main forms: The malposition dislocation, secondary to an error in the position of one of the prosthetic pieces, and mainly of the acetabular cup; the dislocation by muscular discoaptation, where the arthroplasty has discompensated a precarious muscular balance. The authors present a statistical validation of the model regarding 52 dislocations which occurred during the follow-up of 1196 hip arthroplasties. A "control" group was composed of 50 prostheses taken at random within the non-dislocated hips. The total rate of dislocation was 4.30 per cent. Every second one showed to be of malposition origin with a significant limitation of the theoretical intra-prosthetic amplitudes. These dislocations--all appearing early--were, for half, of the anterior type, and in that case, were mainly due to an excess of acetabular anteversion (average 35.2 degrees), the other half was of posterior type, with, in particular, a low value of acetabular anteversion (average 11.4 degrees when it was 23.4 degrees in the non-dislocated group). The other dislocations (all posterior and more delayed) corresponded to a defect of muscular coaptation in the "high-risk" patients (previously operated hip, weight loss, necrotic etiology, neuromuscular etiology, old age). Thus, in almost 90 per cent of the cases, the clinical study brought a validation of our model giving a different explanation from the too classical "cam-acting", often held responsible for the dislocation phenomena.

Aged↗
PubMed1991

Psychosocial distress and infertility: men and women respond differently.

The purpose of this study was to evaluate gender differences in psychosocial responses of 449 consecutive first-admission couples in a fertility clinic. Consistent with previous research, infertile women showed higher distress than their partners on a global measure of psychiatric symptoms and subscales of anxiety, depression, hostility, and cognitive disturbances, as well as on measures of stress and self-esteem. When compared with same-sexed population norms on the measure of psychiatric symptoms, both male and female infertile patients were significantly more distressed than average. No evidence was found for unusually high levels of marital or sexual distress at intake. Implications of results for clinical management are explored.

Female↗
PubMed1990

The effect of iodoacetic acid on the electroretinogram and oscillatory potentials in rabbits.

It has been shown that a single injection of iodoacetic acid selectively (but temporarily) abolishes the b-wave of the electroretinogram. We examined whether such use of this chemical further substantiate our claim that the b-wave of the electroretinogram is a composite potential resulting from the summation (or integration) of faster retinal potentials, usually referred to as the oscillatory potentials. Full-field electroretinograms were recorded from adult New Zealand rabbits before and after a single, bolus injection of 15 mg/kg of buffered iodoacetic acid. Both the 1-1000 Hz electroretinogram and the 100-1000 Hz oscillatory potentials were recorded simultaneously. The oscillatory potentials considered in this study were those normally seen on the rising phase of the b-wave. Following the intravenous injection of iodoacetic acid, there was a progressive decrease in the amplitude and peak time of the b-wave. This observation also was reflected in the oscillatory potential recordings, in which the long-latency oscillatory potentials (3 and 4) progressively disappeared while oscillatory potential 2 remained. We believe that these findings further support our contention that the oscillatory potentials are major components of the b-wave.

Animals↗
PubMed1990

[Dynamic stabilization of a total hip arthroplasty. Apropos of 100 total prostheses of which 52 dislocations].

This paper outlines the principal factors which stabilise a normal hip, and describes the modifications which occur following total joint replacement. Deficiencies in muscle function and mechanical restraints due to the prosthesis may be present. A biomechanical mathematical model has been devised which examines the variations in length of the middle gluteal muscle during movement, particularly in hip flexion, when there is the greatest risk of dislocation. This enables a critical evaluation of the muscle forces surrounding the hip, and allows identification of patients with a high risk of dislocation. These observations have been applied to a group of 100 patients, 52 of whom had experienced a dislocation and 48 with stable prostheses. Patients at high risk according to the statistical model tended to dislocate from one month after operation onwards, and are to be distinguished from those who dislocate early due to malposition of the prosthesis.

Biomechanical Phenomena↗
PubMed1990

Temporal relationship between ERG components and geniculate unit activity in rabbit.

The purpose of this study was to examine if there is an ERG component (alpha-wave, b-wave, oscillatory potentials) which can be used to account for the intraretinal processing time. To address this issue, ERGs and LGN unit responses were recorded simultaneously from anesthetized and paralyzed rabbits. A gradual decrease in the intensity of the light stimulus yields a progressive increase in the latency of the LGN unit response. A similar, highly correlated (r = 0.91 +/- 013), latency shift was also noted for one oscillatory potential (OP2). In comparison, correlation coefficients of r = 0.63 +/- 0.27 and r = 0.70 +/- 0.29 were obtained for the alpha- and b-wave respectively. Furthermore, in 77.6% of the cells examined, OP2 preceded LGN unit activity while the b-wave preceded LGN activity in only 17.8% of the cases. Our results suggest that, of all the retinal potentials considered, the peak time of OP2 better reflects the primary visual processes and the intraretinal time taken for visual processing.

Animals↗
PubMed1990

The oscillatory potentials in response to stimuli of photopic intensities delivered in dark-adaptation: an explanation for the conditioning flash effect.

Previous studies reported that the oscillatory potentials (OPs) evoked to the first flash of a series were always smaller than those produced by the later flashes. This conditioning flash effect (CFE) was suggested to arise from rod inhibition of cone-mediated OPs. We investigated this CFE with the use of two stimulus intensities: 10 cd sec m-2 and 1 cd sec m-2. While the highest intensity did yield the previously reported CFE, the dimmest intensity did not. Our results further indicated that with the brightest stimulus, there is a significant increase in the interpeak interval of the OPs, while dimmest stimuli failed to reveal a similar marked increase. We also noted a significant correlation between the frequency domain of the OPs (as estimated with the interpeak interval) and the amplitude of the OPs (individual or collective: SOPs). Our results would also suggest that the observed CFE could result from a cone inhibition of rod-mediated OPs.

Adaptation, Ocular↗