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Biomedical subjects

N Girard

Publications and source records attributed to N Girard.

At least 55 records · Page 3Linked to original sources
PubMed1999

Differential in vivo regulation of the pituitary growth hormone-releasing hormone (GHRH) receptor by GHRH in young and aged rats.

In aging, alterations of pituitary GH-releasing hormone (GHRH) receptor (GHRH-R)-binding sites have been proposed as one of the initiating factors contributing to the loss of somatotroph responsiveness to GHRH. Changes in the characteristics and/or concentration of the functional GHRH-R could take place in the course of aging and reduce the sensitivity of the somatotroph axis to GHRH. Because chronic exposure to GHRH has been proposed to resensitize aged somatotroph cells, better knowledge of its effects on the regulation of the somatotroph axis is required, particularly at the level of GHRH-R. Two- and 18-month-old male Sprague Dawley rats were treated for 14 days with a daily s.c. injection of 0.5 or 1.0 mg/kg BW human GHRH-(1-29)NH2 or saline. In 2-month-old rats, treatment with 0.5 mg/kg GHRH increased the number of high affinity pituitary GHRH-R-binding sites by 2-fold (P < 0.05) and hypothalamic somatostatin (SRIF) content by 45% (P < 0.05). It did not affect hypothalamic GHRH content, serum total insulin-like growth factor I (IGF-I), or body weight gain. Treatment with 1.0 mg/kg GHRH decreased the number of high affinity pituitary GHRH-R-binding sites by 2.4-fold compared with that in rats treated with 0.5 mg/kg BW (P < 0.05) and increased hypothalamic SRIF content by 45% (P < 0.05), but did not affect GHRH content. It also decreased circulating levels of IGF-I by 13% (P < 0.05) and slowed the growth rate by 17% (P < 0.05). In 18-month-old rats, treatment with 0.5 mg/kg GHRH for 14 days was not sufficient to rejuvenate pituitary GHRH binding parameters. However, treatment with 1.0 mg/kg GHRH restored the affinities of high and low affinity classes of GHRH-binding sites to values similar to those found in 2-month-old rats. Binding capacities of the high and low affinity classes of sites were increased by 1.8- and 3-fold, respectively, although significance was only reached for the low affinity site (P < 0.05). These changes were associated with a normalization of the level of 2.5-kb GHRH-R messenger RNA transcript, which was decreased by 31% in aging rats (P < 0.05), and by a trend for an increase in the 4-kb GHRH-R messenger RNA transcript, which was already increased by 49% in 18-month-old rats (P < 0.05). A normalization of serum IGF-I levels, which were decreased by 11% in 18-month-old control rats (P < 0.01), was also observed. No treatment effect was detected on body weight or hypothalamic SRIF and GHRH contents. We conclude that a 14-day administration of GHRH induces a differential GHRH-R-mediated regulation at the level of the pituitary and probably the hypothalamus as a function of age.

Aging↗
PubMed1999

Idiopathic temporal encephalocele: report of two cases.

BACKGROUND: Idiopathic brain herniation into the middle ear is a rare condition that represents diagnostic and therapeutic challenges. OBJECTIVE: The authors present here two new cases of idiopathic brain herniation with special clinical presentation and emphasis on radiographic studies, particularly computed tomographic scan and magnetic resonance imaging, which allowed the authors to detect the malformation. RESULTS: The two patients underwent surgical treatment with infratemporal approach and recovered perfectly.

Diagnosis, Differential↗
PubMed1999

Assessing the practicality of research findings for clinical practice.

Reading research articles can be challenging, but it also can be stimulating. Once you get a system for reviewing articles and interpreting their worth and value to your practice, you will find much usable information. Reviewing articles with the focus of assessing their importance to clinical practice could be done with a research committee of your local AORN chapter. It also would be an interesting and informational chapter program to have a panel discuss the relevance of two or three studies to perioperative practice. This process and type of information also can be used if your institution is developing research teams. Assessing the practicality of research to your practice is essential. Research is not a mystery; it is the answer to a mystery. It is necessary to the future of perioperative nursing. Change practice with empirical evidence!

Data Interpretation, Statistical↗
PubMed1998

Association between licensing examination scores and resource use and quality of care in primary care practice.

CONTEXT: Clinical competence is a determinant of the quality of care delivered, and may be associated with use of health care resources by primary care physicians. Clinical competence is assumed to be assessed by licensing examinations, yet there is a paucity of information on whether scores achieved predict subsequent practice. OBJECTIVE: To determine if licensing examination scores were associated with selected aspects of quality of care and resource use in initial primary care practice. DESIGN: Prospective cohort study of recently licensed family physicians, followed up for the first 18 months of practice. SETTING: The Quebec health care system. PARTICIPANTS: A total of 614 family physicians who passed the licensing examination between 1991 and 1993 and entered fee-for-service practice in Quebec. MAIN OUTCOME MEASURES: All patients seen by physicians were identified by the universal health insurance board and all health services provided to these patients were retrieved for the 18 months prior to (baseline) and after (follow-up) the physicians' entry into practice. Medical service and prescription claims files were used to measure rates of resource use (specialty consultation, symptom-relief prescribing compared with disease-specific prescribing) and quality of care (inappropriate prescribing, mammography screening). Baseline data were used to adjust for differences in practice population. RESULTS: Study physicians saw a total of 1116389 patients, of whom 113535 (10.2%) were elderly and 83391 (7.5%) were women aged 50 to 69 years. Physicians with higher licensing examination scores referred more of their patients for consultation (3.8/1000 patients per SD increase in score; 95% confidence interval [CI], 1.2-7.0; P = .005), prescribed to elderly patients fewer inappropriate medications (-2.7/1000 patients per SD increase in score; 95% CI, -4.8 to -0.7; P=.009) and more disease-specific medications relative to symptom-relief medications (3.9/1000 patients per SD increase in score; 95% CI, 0.3 to 7.4; P= .03), and referred more women aged 50 to 69 years (6.6/1000 patients per SD increase in score; 95% CI, 1.2-11.9; P = .02) for mammography screening. If patients of physicians with the lowest scores had experienced the same rates of consultation, prescribing, and screening as patients of physicians with the highest scores, an additional 3027 patients would have been referred, 179 fewer elderly patients would have been prescribed symptom-relief medication, 912 more elderly patients would have been prescribed disease-specific medication, 189 fewer patients would have received inappropriate medication, and 121 more women would have received mammography screening. CONCLUSIONS: Licensing examination scores are significant predictors of consultation, prescribing, and mammography screening rates in initial primary care practice.

Adult↗
PubMed1998

Prognostic value of proton MR spectroscopy of cerebral hemisphere tumors in children.

We studied 14 young people with newly diagnosed hemisphere tumors, aged from 3 to 20 years (average 10 years). All underwent surgery following MR imaging (MRI) and spectroscopy (MRS). The tumors studied were three glioblastomas, one each of ganglio-glioblastoma, primitive neuroectodermal tumor (PNET), rhabdoid teratoid tumor, pilocytic astrocytoma, ependymoma, anaplastic ependymoma, and gliomatosis cerebri, and four gangliogliomas. Four patients died; ten patients are alive (five with stable residual tumor, five with no evident tumor). Images and spectra were acquired on a 1.5-T imager. Proton MRS was performed before gadolinium injection in all but one case. Single-voxel techniques were utilized in all cases, using a spin-echo or STEAM sequence with a long echo time (135 or 270 ms). Peak areas of N-acetyl aspartate (NAA), choline (Cho), and creatine and phosphocreatine (Cr) were assessed. The NAA/Cho peak-area ratio was very low in the patients who died (mean +/- s.d. 0.20 +/- 0.14), and higher in the patients who are alive (0.74 +/- 0.47; P = 0.007 by two-tailed t-test). The Cr/Cho peak-area ratio also followed a similar trend for the two groups (mean +/- s.d. 0.17 +/- 0.07 and 0.49 +/- 0.30, respectively; P = 0.01 by two-tailed t-test).

Brain↗
PubMed1998

Hyaluronectin is produced by oligodendrocytes and Schwann cells in vitro.

A hyaluronectin (HN)-like antigen was found in rat O-2A progenitors and oligodendrocytes, as well as in Schwann cells and in their culture medium. The HN-like antigen secreted in culture supernatants had a higher molecular mass than HN extracted from rat brain at acidic pH. In vitro the secreted HN-like antigen was spontaneously and slowly degraded into species whose Mr was close to that of HN found in acidic brain extract. In brain or nerve neutral pH extracts, both HN-like antigen and HN were present. The high Mr of the secreted antigen, the homology in amino acid sequences between HN and N-terminal domain of PG-M/versican, in addition to a positive hybridization between Schwann cell RNAs and a probe obtained with primers derived from HN sequences also found in versican suggested that HN is closely related to the large proteoglycan PG-M/versican. The presence in Schwann cell extract of a HN mRNA whose Mr was compatible with the size expected for HN showed that HN may be directly secreted by cells and not only the consequence of a proteolytic cleavage. The similarity of HN with PG-M (V3) suggested that HN found in vivo could be the result of an alternative splicing of a single gene. We conclude that HN as other members of the PG-M/versican family is a marker of oligodendrocytes and Schwann cells in culture.

Animals↗
PubMed1998

Predictive significance of magnetic resonance imaging at 4 months of adjusted age in infants after a perinatal neurologic insult.

The aim of this prospective study was to evaluate the predictive significance of magnetic resonance imaging (MRI) performed at 4 months of corrected age in 60 neonates after a perinatal neurologic insult. Follow-up ranged from 2 to 5 years of chronological age. MRI examination was normal in 10; isolated external hydrocephalus was found in 15 infants. Twenty-three of these infants developed normally. Focal or multifocal lesions were shown in 6 infants, of whom 2 developed normally. Diffuse brain involvement was present in 29 cases as atrophy (n = 18), leukomalacia (n = 5), basal ganglia lesions (n = 3), and delayed myelination (n = 3). All but 4 infants showed neurologic impairment. MRI performed at 4 months of adjusted age is of prognostic significance in neonates who suffer a moderate or mild neurologic insult.

Basal Ganglia↗
PubMed1998

Long-term calorie restriction protects rat pituitary growth hormone-releasing hormone binding sites from age-related alterations.

In mammals, middle age and late adulthood is characterized by a decrease of growth hormone (GH) secretion and insulin-like growth factor 1 (IGF-1) serum levels, contributing to tissue and organ atrophy. This condition is related, at least in part, to alterations of pituitary GH-releasing hormone (GHRH) receptor-binding sites. Prevention of age-related deterioration of tissues and organs, retardation of the onset or progression of a wide range of age-related diseases and extension of both mean and maximum life span can be achieved through life-long moderate calorie restriction (CR). Because CR has been reported to positively modulate the somatotropic axis resulting in the maintenance of a youthful GH secretory pattern in aged rats, we investigated whether or not benefits of a long-term (10 months) 40% CR, started in 8-month-old male Sprague-Dawley rats, was accomplished by preventing age-related alterations of pituitary GHRH receptor binding sites. We also studied whether or not a short-term (50 days) 40% CR, started in 16-month-old rats, could revert them. Potential hormonal and metabolic modulators of the GHRH receptors were investigated as well. GHRH binding parameters were derived from saturation studies performed in pituitary homogenates with [125I-Tyr10]hGHRH (1-44)NH2. As previously reported, the high affinity GHRH receptor-binding sites were blunted in 18-month-old ad libitum-fed rats and the apparent concentration of total binding sites was reduced. Short-term CR neither restored high affinity GHRH binding sites nor increased the apparent concentration of total binding sites. On the contrary, long-term calorie-restricted 18-month-old rats exhibited high and low affinity GHRH binding sites (Kd1: 1.73 +/- 0.35 nM; Kd2: 310 +/- 41 nM; Bmax1: 183 +/- 55 fmol/mg protein; Bmax2: 30 +/- 3 pmol/mg protein) as found in 2-month-old rats (Kd1: 0.68 +/- 0.15 nM; Kd2: 350 +/- 47 nM; Bmax1: 219 +/- 53 fmol/mg protein; Bmax2: 84 +/- 9 pmol/mg protein). Our results imply that CR must be implemented before age-related alterations of GHRH receptor-binding sites become too severe or that CR has to be carried out for a long period of time, independently from the age at which it begins. Protection of pituitary GHRH binding sites from age-related alterations could not be attributed to changes in circulating levels of total or free T4 or free fatty acids. Finally, the anti-aging effect of a long-term CR observed at the level of pituitary GHRH receptors does not result in a significant increase of total IGF-1 circulating levels. Identification of molecular and cellular mechanisms responsible for these actions will deserve attention in order to identify centrally and/or peripherally active classes of molecules that could preserve, in aging mammals, the functionality of the somatotropic axis through selective regulation of pituitary GHRH receptors.

Aging↗
PubMed1998

Prenatal diagnosis of fetal corpus callosum agenesis by ultrasonography and magnetic resonance imaging.

Corpus callosum agenesis (CCA) was evaluated by ultrasound examination and magnetic resonance imaging (MRI) in 14 cases. Ultrasonography was able to suspect CCA by indirect signs but a definitive diagnosis of CCA was achieved in only four cases. MRI was able to diagnose complete CCA in 13 cases and showed absence of the posterior portion of the corpus callosum in one case. Additional neurological abnormalities including heterotopia, gyration anomaly, asymmetry of the cerebral hemispheres, and Dandy-Walker variant were documented in five cases, as well as an ocular anomaly which was present in one case, by MRI examination. Prenatal counselling for fetal agenesis of the corpus callosum is difficult as the prognosis is uncertain. The association with other cerebral abnormalities increases the likelihood of a poor outcome and ultrasonographic assessment of the fetal brain is limited. We found MRI to be a safe and useful additional procedure to complement ultrasonographic diagnosis or suspicion of CCA.

Adult↗
PubMed1998

[Anatomic MRI study of commissural agenesis and dysplasia of the Telencephalon (Agenesis of the corpus callosum and related anomalies). Clinical correlations and morphogenetic interpretation].

A series of 78 patients presenting with agenesis of the cerebral commissures and properly investigated with MR imaging, was reviewed and analyzed morphologically. Results were compared with descriptive data from the literature, and with the developmental models proposed. From this, a model of a-commissural brain is described: the lamina terminalis would be homologous to a telencephalic anterior medullary velum of which the commissure would be the anterior commissure, and the lamina of white matter described as the Probst's and the fornical bundles, would be homologous to a posterior medullary velum having become a medial medullary velum due to the division of the prosecephalon into two cerebral hemispheres, and of which the commissure would be the (posterior) calloso-hippocampal commissure. Also, the comparison with the model establishes that in the actual malformations, defects of the cingulum and of at least some of the intralobaroccipital association bundles are observed beside the commissural defect. Such a model would reclassify these disorders, distinguishing the "simple" commissural defects, complete or segmental, global or dissociated, without or with a ventricular expansion, from more complex forms with multicystic defects, adding major dysplastic lesions of the dura mater, leptomeninges and parenchyma, to the commissural defects. Paradoxically, the latter group seems to be clinically less severe than the "simple agenesis" group, of which prognosis (including the neurologic and intellectual disorders as well as the associated pathologies) is generally very poor; this should be seriously considered since the antenatal diagnosis of these malformations is made routinely with ultrasonography and MRI.

Agenesis of Corpus Callosum↗
PubMed1997

Increased hyaluronidase levels in breast tumor metastases.

Hyaluronidase, a matrix-degrading enzyme, was assayed in extracts from breast primary tumors and regional metastases using a pool of human sera as a standard. Optimal activities of tumor extracts and serum were found for concentrations of 0.15-0.20 M NaCl in pH 3.8-4.0 buffer. In evaluating contamination by serum due to vascular proliferation, we expressed our results as the ratio of the entire activity (mU/l extract) on serum albumin content of tumors (g/l). Median (interquartile range) activities were 9.02 (6.04-14.34) for primary tumors and 37.36 (24.06-99.63) mU/g albumin for metastases. The difference was significant. Zymographic analysis showed that 3 bands of activity were detected which corresponded to 68, 53 and 49 kDa for tumoral hyaluronidase. The same pattern was observed for cellular extracts of breast cancer cell line CAL51, demonstrating that hyaluronidase detected in tumor extracts had mainly a cellular origin. Our results suggest that hyaluronidase may be involved in the metastatic process.

Breast Neoplasms↗
PubMed1997

The origin of hyaluronectin in human tumors.

The origin of tumor stroma hyaluronectin (HN), a glycoprotein that binds to hyaluronan (HA), has long remained unknown. Histological observations of human tumors suggest that tumor HN could originate from stroma fibroblasts, and in some cases from inflammatory cells. The fibroblast origin was confirmed by the discovery of HN-like antigen along with hyaluronan in culture medium of tumor-derived fibroblasts. An HA-binding protein was characterized in the culture medium of peripheral blood mononuclear cells (PBMC) in both normal subjects and tumor-bearing patients and was found to be human HN. Cultivated monocytes did not produce HA. HN was not related to the HA-binding site CD44. Sequencing of brain HN-derived peptides demonstrated that each determined peptide sequence was similar to a sequence of the proteoglycan PG-M/versican, suggesting that HN is the HA-binding moiety of the proteoglycan. One probe was synthesized from human PBMC by polymerase chain reaction with primers derived from HN sequences also found in versican. Northern blots were positive only with HN-producing cells. The main RNAs were in the 6-8 kb range, and there was a limited proportion of smaller RNA, which was compatible with the size expected from the HN molecular mass. Southern blotting of monocytes and tumor cells demonstrated that the gene was limited to a unique band. We conclude that HN, an extracellular component of brain, connective embryonic, inflammatory and tumoral tissues, is a PG-M/versican-derived molecule. Our results suggest that tumor HN, which originates from fibroblasts and monocytes of tumor stroma, is a molecular component of the host-tumor relationship and could play a role in the regulation of HA activity in oncogenesis.

Adenocarcinoma↗
PubMed1997

Three-dimensional MRI of hemifacial spasm with surgical correlation.

MRI was used to investigate 100 patients with hemifacial spasm, using 3D-FT T2-weighted (CISS) and contrast-enhanced 3D-FT T1-weighted (turbo-FLASH) sequences in all cases. MR angiography was performed in 54 patients, using 3D-MT FISP images. Decompression of the facial nerve through a retromastoid craniotomy was performed in all patients. Hemifacial spasm caused by tumours in the cerebellopontine angle was not included. Vascular contact with the facial nerve root-exit zone or at the internal auditory canal was present in 96 of 100 patients with hemifacial spasm. The vessel responsible was the vertebral artery (VA) in 18 cases, the posterior inferior cerebellar artery (PICA) in 23, the anterior inferior cerebellar artery (AICA) in 22, the VA and PICA in 24, VA and AICA in 3, PICA and AICA in 1, VA, PICA and AICA in 4, and a vein in 1 case. CISS images showed compressive vascular loops better than contrast-enhanced turbo-FLASH images alone. The sensitivity of MRI was high, since only one false-negative case was found among the 100 patients who underwent surgery.

Adult↗
PubMed1997

Magnetization transfer in the investigation of patients with tuberous sclerosis.

We examined 21 patients aged 5 months to 19 years, on a 1.5 T magnet. T1-weighted spin-echo images, proton density and T2-weighted images with spin-echo and turbo spin-echo sequences, and contrast-enhanced magnetization transfer (MT) T1-weighted images were obtained in all cases. MT T1-weighted images were performed before injection in 9 patients. Subependymal nodules were found in 14, and cortical and subcortical tubers in 20 of the 21 patients. MT T1-weighted images showed tubers and subependymal nodules as higher signal than normal gray matter and revealed more tubers than conventional sequences in 11 cases. High signal intensity lesions of the white matter were found in 19 patients but were seen only on MT images in 9 cases. When MT images both before and after injection were available, tubers and white matter lesions were more easily recognised on unenhanced MT images because of their higher contrast.

Adolescent↗
PubMed1997

[Periarteritis nodosa disclosed by epilepsy in a drug addict with hepatitis B and C virus carrier state].

The authors report a case of periarteritis nodosa (PAN) with an inaugural symptom of febril epilepsy. The patient was drug addict with hepatitis B and C virus. A toxoplasmic lesion originally noted on the cranial computed tomography scan was confirmed by cerebral magnetic resonance imaging showing encephalitis, and a diagnosis of periarteritis nodosa was suggested by clinical signs and laboratory data. The responsibility of hepatitis B virus in the genesis of this PAN seems quite certain whereas possible others factors such as hepatitis C virus or cocaine are discussed.

Adult↗
PubMed1997

Hyaluronan: fundamental principles and applications in cancer.

Hyaluronan (HYA) plays a particular role in cancer cell microenvironment. A component of the desmoplasia. HYA is associated to other macromolecules and contributes to the net structure of the matrix. Cancer cells exhibit binding sites (CD44, RHAMM) for HYA. The cell adhesion to HYA can influence the cell motility and different factors could interplay to facilitate cell detachment from HYA. HYA protects cancer cells against immune cell attack. Serum HYA is often increased in metastatic patients.

Animals↗