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Biomedical subjects

J Guerin

Publications and source records attributed to J Guerin.

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

Morphologic and histologic study of the ligamentum flavum in the thoraco-lumbar region.

The ligamentum flavum, of which there are only a few studies in the literature, has several features discussed in this work. On the macroscopic level, it has a metameric arrangement: it has two layers, superficial and deep, whose fibers are opposite, and it has close relations with the tendons of attachment of some spinal erector muscles. On the microscopic level, its structure is unique for a ligament, because of a predominance of elastic fibers, because of its intrinsic innervation at each level of the spine, and because this innervation grows poorer with increasing degeneration. The ligamentum flavum constitutes an active ligament, with an essential biomechanical role. Its injury is probably not without consequences, and therefore there are many technical problems about the surgical interlaminar approach.

Aged↗
PubMed1998

Implantation of anterior sacral root stimulators combined with posterior sacral rhizotomy in spinal injury patients.

Brindley-Finetech sacral anterior root stimulators combined with posterior sacral rhizotomy were implanted in 68 males and 28 females with spinal cord lesions. In 9 patients the electrodes were implanted extradurally in the sacrum, and in 90 patients they were implanted intradurally (3 patients had a second extradural implant after a first intradural implant). Three patients died from causes unrelated to the implant. Of the 93 surviving patients, 83 used their implants for micturition and 82 were fully continent. The mean bladder capacity increased from 206 ml preoperatively to 564 ml after the operation. Three patients had a preoperative vesicorenal reflux that disappeared after surgery. In all, 51 patients used the stimulator for defecation. Erection was possible with electrical stimulation in 46 males and was used for coitus by 17 couples. Secondary deafferentation at the level of the conus was performed four times. Three patients who had a cerebrospinal fluid leak were operated on again. Two implants had to be removed because of infection. Sacral anterior root stimulation combined with sacral deafferentation is a welcome addition to the treatment of neurogenic bladder in spinal cord injury patients.

Adult↗
PubMed1998

Antibodies to prothrombin in antiphospholipid syndrome and inflammatory disorders.

Antiphospholipid antibodies associated with the antiphospholipid syndrome (APS) have been shown to bind plasma proteins, particularly beta 2-glycoprotein I (beta2-GPI). In this study the incidence of antibodies to solid-phase prothrombin was examined in patients with antiphospholipid syndrome and a variety of other inflammatory disorders. Significantly elevated levels of IgG anti-prothrombin (anti-PT) antibodies were detected in 63% of patients with APS (n = 27, median 22 arbitrary units: AU), 33% with SLE (n = 92, median 14 AU). 45% with rheumatoid factor (n = 22, median 16 AU), 21% with carotid artery stenosis (n = 21, median 15 AU), 32% with stroke (n = 38, median 13 AU). 67% of patients with a false positive serology for syphilis (n = 21, median 24 AU), 37% with HIV (n = 30, median 14 AU), 29% with syphilis (n = 14, median 19 AU) and 3% with infectious mononucleosis (n= 30, median 9 AU). In addition, a group of lupus anticoagulant (LA) positive patients (n = 48) was examined for antibodies to prothrombin, beta2-GPI and cardiolipin. 10 (21%) patients had raised levels of IgG anti-PT antibodies, 30 (62%) had significantly elevated levels of anti-beta2-GPI antibodies and 15 (31%) had elevated levels of anticardiolipin antibodies (ACA). Of the LA-positive patients, 15 (43%) were identified with definite APS, eight (23%) with probable APS, two (6%) with possible APS and 10 (28%) patients had no clinical evidence of APS. In conclusion, antibodies to prothrombin were found in a variety of inflammatory disorders and were therefore not specific for the APS. However, identification of the plasma proteins recognized by antibodies from patients with APS may provide insight into the pathogenic mechanisms involved in the heterogenous clinical manifestations of the APS.

Antibodies, Anticardiolipin↗
PubMed1998

Comparative evaluation of conventional and dynamic magnetic resonance imaging of the pituitary gland for the diagnosis of Cushing's disease.

OBJECTIVES: The ability of MRI to detect pituitary ACTH-secreting adenomas in patients with Cushing's disease is limited. Owing to different dynamics of contrast enhancement between adenomas and normal pituitary tissue, it has been suggested that obtaining images within seconds after gadolinium (Gad) injection using dynamic procedures increases the sensitivity of MRI in the detection of pituitary microadenomas. The objective of this study was to compare the ability of conventional magnetic resonance imaging (CMRI) and dynamic MRI (DMRI) to detect ACTH-secreting pituitary adenomas. DESIGN: Twenty-six consecutive patients with ACTH-dependent Cushing's syndrome and 10 normal subjects were investigated. According to the results of inferior petrosal sinus sampling, 21 patients had Cushing's disease and five had ectopic ACTH syndrome. Patients with Cushing's disease were operated regardless of the results of imaging studies. All underwent identical MRI and DMRI procedures using a 1.0 T magnet. Image sampling time during DMRI was 19 sec. Scans were randomly mixed and analysed blind, retrospectively and independently by two experienced radiologists. The clarity of the images was assessed by the analysis of agreement among radiologists. MRI findings were compared to surgical and histopathological findings. RESULTS: Surgical exploration identified three macrodenomas and 14 microadenomas. One microadenoma was found at pathological examination after subtotal hypophysectomy and no tumour was found in three cases. According to the combined opinion of radiologists, the three macroadenomas were identified equally well with CMRI and DMRI. Eight ACTH-secreting microadenomas were detected with CMRI and 11 with DMRI. The three microadenomas detected with DMRI only were visualized within 60 sec following Gad injection. No false positives occurred with CMRI. Three false positives were obtained with DMRI: one in a patient with ectopic ACTH syndrome while a silent microprolactinoma and normal tissue were found at the site of the radiological abnormality in two patients with Cushing's disease. In our study, the sensitivity of DMRI is greater than that of CMRI (0.67 vs. 0.52) but is associated with a loss in specificity (0.80 vs. 1.00). False positives may result from the increased sensitivity of DMRI which detects incidental pituitary lesions, technical artefacts or lowest clarity of images, as suggested by a lower observer agreement of DMRI (Kappa statistic 0.66 vs. 0.83). Overall, the two MR procedures had equivalent diagnostic power (0.72). CONCLUSIONS: In our hands, dynamic procedures did not improve the usefulness of MRI in Cushing's syndrome.

ACTH Syndrome, Ectopic↗
PubMed1998

High throughput analysis of differential gene expression.

Elucidation of the changes in gene expression associated with biological processes is a central problem in biology. Advances in molecular and computational biology have led to the development of powerful, high-throughput methods for the analysis of differential gene expression. These tools have opened up new opportunities in disciplines ranging from cell and developmental biology to drug development and pharmacogenomics. In this review, the attributes of five commonly used differential gene expression methods are discussed: expressed sequence tag (EST) sequencing, cDNA microarray hybridization, subtractive cloning, differential display, and serial analysis of gene expression (SAGE). The application of EST sequencing and microarray hybridization is illustrated by the discovery of novel genes associated with osteoblast differentiation. The application of subtractive cloning is presented as a tool to identify genes regulated in vivo by the transcription factor pax-6. These and other examples illustrate the power of genomics for discovering novel genes that are important in biology and which also represent new targets for drug development. The central theme of the review is that each of the approaches to identifying differentially expressed genes is useful, and that the experimental context and subsequent evaluation of differentially expressed genes are the critical features that determine success.

Animals↗
PubMed1997

Antibodies to beta2-glycoprotein I--a specific marker for the antiphospholipid syndrome.

The antiphospholipid syndrome is a disorder characterized by recurrent thrombosis and the presence of antibodies specific to phospholipids. However, the diagnosis of this syndrome is hampered by the lack of a specific laboratory test. In this study an ELISA for the measurement of antibodies to solid-phase beta2-glycoprotein I (beta2-GPI) was established and compared with anticardiolipin antibodies for diagnosis of antiphospholipid syndrome. Significantly elevated levels of antibodies to beta2-GPI were found in all patients with definite antiphospholipid syndrome (median = 91 AU). Marginally elevated levels of antibodies to beta2-GPI were observed in 5% of patients with systemic lupus erythematosus (SLE; median = 4 AU), 1% with stroke (median = 3 AU), 13% with infectious mononucleosis (median = 3 AU), 10% with HIV infection (median = 3 AU) and 8% with VDRL false-positive serology for syphilis (median = 4 AU), but not in patients with rheumatoid factor, syphilis or carotid artery stenosis. In contrast, significantly raised levels of anticardiolipin antibodies were observed in 100% of patients with definite antiphospholipid syndrome, 30% with SLE, 88% with HIV infection, 94% with syphilis, 62% with infectious mononucleosis, 9% with rheumatoid factor-positive sera, 74% VDRL false-positive serology for syphilis, 47% with stroke and 0% with carotid artery stenosis. This solid-phase assay for antibodies to beta2-GPI is highly specific for the antiphospholipid syndrome and represents an advance in the laboratory diagnosis of this disorder.

Antibodies, Anticardiolipin↗
PubMed1997

Study and course of the psychological profile in 77 patients expressing panic disorder with agoraphobia after cognitive behaviour therapy with or without buspirone.

BACKGROUND: The change of psychopathological dimensions during treatment of panic disorder is attracting increasing interest. METHODS: A population of subjects experiencing panic disorder with agoraphobia is evaluated with the French version of the factor structure of the Symptom Checklist 90 R (SCL 90 R). Two groups of patients are compared: a group receiving cognitive behaviour therapy (CBT) combined with buspirone and a group receiving cognitive behaviour therapy combined with placebo. RESULTS: Comparative analysis of pre- and post-test changes between both groups completing treatment showed that the combination cognitive behaviour therapy plus buspirone provided better results than those in patients who had received cognitive behaviour therapy plus placebo. This difference between treatments did not persist at the 1-year follow-up, since, while results had been effectively maintained in the CBT plus buspirone group, the CBT plus placebo group continued to improve significantly for the target dimensions of treatment. CONCLUSIONS: Psychopathological dimensions on the SCL 90 R show that combination of buspirone and cognitive behaviour therapy accelerates the behaviour modification process only in the short term.

Adult↗
PubMed1997

The widened retrolabyrinthe approach: a new concept in acoustic neuroma surgery.

For many years, the retrolabyrinthine approach has been limited to functional surgery of the cerebellopontine angle (CPA). As a result of the increased surgical exposure, particularly the opening of the internal auditory meatus (IAM), the widened retrolabyrinthine technique permits tumor excision from both the CPA and the IAM, regardless of the histological nature of the tumor. The authors have treated 60 acoustic neuromas of varying sizes via this approach (6% intrameatal tumors; 30% > 25 mm in diameter). The postoperative mortality rate was 0%. The risk of fistula formation was 3.3%, and 3.3% of the patients suffered from postoperative meningitis. The results for facial nerve function were equivalent to those obtained previously via a widened translabyrinthine approach and those in a series treated via a suboccipital approach (80% with Grades I and II, 15% with Grade III, and 5% with Grades V and VI). One patient (1.7%) required a secondary hypoglossal-facial nerve anastomosis and had attained a Grade IV result 6 months later. Postoperatively 21.7% of these patients maintained socially useful hearing and 20% had mediocre hearing. Socially useful hearing was preserved in 50% of a subgroup of 20 patients who had both good preoperative hearing and a tumor that involved less than half of the IAM regardless of its volume. Additionally, 15% had mediocre hearing that could be improved with hearing aids. Because of its efficacy in preserving hearing, the authors favor the retrolabyrinthine over the occipital approach, with the latter being considered less subtle and more aggressive.

Adult↗
PubMed1996

[Enlarged retro-labyrinthic approach: application to surgery of acoustic neurinoma. Apropos of 55 cases].

The enlarged retro-labyrinthic route described here allows opening of the internal auditory canal, exeresis of tumors localized in the ponto-cerebellous angle and in the internal auditory canal. We used this route for 55 neurinomas of the auditory nerve (7.4% stage I, 23.6% stage II, 45.4% stage III and 23.6% stage IV). Most of the tumors in our series were > 2 cm. There were no post-operative deaths. Risk of fistulization was low, 3.8%. Post-operative meningitis (3.8%) regressed rapidly with treatment. Facial function outcome was equivalent to that obtained with the enlarged trans-labyrinthic route and reported in the literature in series treated via the sub-occipital route (83.6% for grades I and II, 11% for grade III). One patient required hypoglosso-facial anastomosis with a grade IV result at 6 months. Auditive function was preserved at a socially acceptable level in 14.5% of the patients and in 21.8% hearing aids were needed. Selecting a subgroup of 25 patients with good quality hearing prior to surgery (< 30 dB) and a tumor invading less than three-fourths of the internal auditory canal, for all tumor sizes, 28% preserved socially acceptable hearing. To these must be added 20% who had some hearing loss which could be corrected. The modulary mature of the retrolabyrinthic route is easily transposable to the trans-labyrinthic rout. Because of the potential for preserving auditive function this technique should replace the less flexible sub-occipital route.

Audiometry↗
PubMed1995

Calibration of an in vitro assay system using a non-adherent cell line to evaluate the effect of a drug on Toxoplasma gondii.

A TG 180 non-adherent cell culture with Toxoplasma gondii and spiramycin was performed in order to calibrate TG 180 cells used in a therapeutic assay system. TG 180 cells were infected with the RH strain of T. gondii, and spiramycin was added at final concentrations of 1, 2, 4, 8, 12, 16, 20 and 25 micrograms/ml. A least-squares linear regression with confidence interval was calculated from the experimental curve and allowed the determination of the 50% inhibitory concentration of spiramycin. The IC50 of 13.7 micrograms/ml obtained is comparable with the results of the literature. The system including TG 180 cells (recently cultured in vitro) provides a rapid, accurate and economical determination of the effects of a drug on Toxoplasma gondii.

Animals↗
PubMed1995

[Implantable sites in cancerology. The percutaneous technique. Results of a homogeneous series of 141 cases].

Percutaneous implantation sites were used by the same operator in 141 patients (87 females and 54 males) with usually metastatic cancer. A titanium Districath implantable chamber and a 1.1 mm inner diameter silicone catheter were used. Percutaneous venous access was via the subclavian vein in 139 cases (98.6%). Mandatory safety measures were emphasized. Insertion was complicated by puncture of the subclavian artery in 6 cases (4.2%). There were no case with abscess, disunion, infection or death due to the method. The chamber was removed in 7 cases due to: 3 ruptures of the catheter, 2 septicaemias, 1 rejection reaction and 1 psychological intolerance. In our series, percutaneous implantation via the subclavian vein has been a reliable and rapid technique with little morbidity.

Adult↗
PubMed1994

Gonadotropin-releasing hormone induced Ca2+ influx in nonsecreting pituitary adenoma cells: role of voltage-dependent Ca2+ channels and protein kinase C.

The action mechanism of gonadotropin-releasing hormone (GnRH) on the cytosolic free calcium concentration ([Ca2+]i) and high-threshold voltage-dependent Ca2+ channel activity was studied in human nonsecreting (NS) pituitary adenoma cells. [Ca2+]i was monitored in individual cells by dual emission microspectrofluorimetry using indo 1 as intracellular fluorescent Ca2+ probe. The whole-cell recording patch-clamp technique was used to study Ca2+ channels. A short application of GnRH (1 to 100 nM) induced an increase in [Ca2+]i due to Ca2+ entry through plasma membrane voltage-sensitive L-type Ca2+ channels. Protein kinase C (PKC) depletion induced by a pretreatment with 1 microM PMA for 24 h abolished spontaneous Ca2+ transients and the action of GnRH on [Ca2+]i and Ca2+ channels. Phloretin (250 microM) and staurosporine (20 nM), two protein kinase C inhibitors, inhibited Ca2+ channel activity, thereby suppressing the effect of GnRH. On the other hand, activation of PKC by a short application of phorbol myristate acetate (10 nM) stimulated Ca2+ influx through Ca2+ channels. These findings demonstrate that, in human NS adenoma cells, GnRH (1 to 100 nM) induces an increase in [Ca2+]i, principally due to Ca2+ entry through L-type voltage-activated Ca2+ channels. PKC regulates this mechanism as well as basal ion channel activity, thus exerting both positive and negative control of [Ca2+]i in stimulated and unstimulated NS adenoma cells.

Adenoma↗
PubMed1993

Evolution of bladder contraction in course of time after implantation of a sacral anterior root stimulator.

We reviewed bladder contraction evolution after sacral anterior root stimulator implantation in thirty patients operated on from 1984 to 1991. Two patients underwent a complete denervation with a reinnervation within a maximal time of seventeen months. One patient underwent a lesion, like a neuropraxia with a complete recovery at four months. Five patients have undergone a partial denervation with a recovery of miction by neurostimulation within the time of eighteen months. In three patients, bladder contraction disappeared for various reasons.

Electric Stimulation Therapy↗
PubMed1993

[Electrostimulation of anterior sacral nerve roots in the treatment of central neurogenic bladders. G.S. Brindley's technique. Results of the 40 first French cases].

The results of the first 40 cases who underwent implantation of a sacral anterior root stimulator (G.S. Brindley) in France are reported. One patient die two years after implantation from an unrelated cause. 39 patients are using electrostimulation with a 6 month to 8 year follow-up. 90% have a satisfactory continence and no longer require an incontinence appliance. 82% of the patients have a post-void residue of 0 to 50 cc. Urinary infection rate has dramatically decreased. Bladder capacity and compliance have increased, and urethral closure pressure has decreased according to posterior rhizotomy. Possible side effect of total posterior rhizotomy from S2 to S4 could be stress incontinence.

Adult↗
PubMed1992

A pineal tumour with features of "pineal anlage tumour".

A primitive tumour of the pineal region in a 9 month-old boy caused hydrocephalus, ataxic gait and paraplegia leading to death after 9 months of evolution. Histological and histochemical examination revealed a pinealoblastoma with melanotic cells as well as cartilaginous formations. The leptomeningeal seeding of the tumour showed neuroblastic and neuronal differentiation. A diagnosis of pineoblastoma with neuroepithelial and ectomesenchymal differentiation was made. This tumour belongs to a recently defined category of pineal tumours, called pineal anlage tumours.

Biomarkers, Tumor↗
PubMed1992

Effect of naloxone and beta-casomorphin on the hypothalamic-pituitary-luteinizing hormone axis in vitro.

The effect of naloxone and beta-casomorphin on luteinizing hormone (LH) release from pituitary cell aggregates, obtained by three-dimensional culture, with or without mediobasal hypothalamic fragments was studied in vitro. Short-term naloxone perifusion at a concentration of 10(-5)M did not modify either basal or LHRH-stimulated LH release from the pituitary cell aggregates. In contrast, a 12-min naloxone perifusion at the same concentration caused an increase in LH release in the mediobasal hypothalamic-pituitary cell aggregate axis. This increase was rapid (12-16 min after time pulse), marked [up to 10 times (p less than 0.004) the initial base line], short (return to the base line secretion 32-40 min after the beginning of the time pulse) and dose-dependent, with a rise greater than 1000% at a concentration of 10(-4) (p less than 0.006). The same effect was observed when a second pulse was applied 48 min after the first one. LH release induced by naloxone was antagonized 56 +/- 2% (p less than 0.03) by beta-casomorphin (an exogenous opiate) at a concentration of 10(-5) M. beta-casomorphin alone did not modify LH basal secretion, but inhibited 25.1 +/- 2.4% (p less than 0.008) LH release enhanced by LHRH. These results indicate that naloxone, an opiate antagonist, markedly increases LH release via a mu-type opioid receptor mechanism at the hypothalamic level only, during short-term exposure.

Animals↗