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Biomedical subjects

F Robert

Publications and source records attributed to F Robert.

230 records · Page 13Linked to original sources
PubMedDate not supplied

Effects of dobutamine on isovolumic and ejection phase indices of cardiac contractility in conscious healthy dogs.

The aim of this study was to determine cardiac contractility using indices derived from cardiac catheterisation in conscious healthy dogs during dobutamine infusion. Eight dogs were studied. An ECG was recorded together with left ventricular pressure and volume which were measured using a conductance catheter with an integrated microtip pressure sensor. Eight indices of left ventricular systolic performance were derived from these records. Measurements were realised under basal conditions and during an incremental dobutamine challenge. The maximal rate of rise in ventricular pressure (max dP/dt), max dP/dt divided by the developed pressure and the mean systolic ejection rate were the most sensitive indices to detect dobutamine induced changes in contractility with maximal percentage changes of 122+/-11 per cent, 130+/-7 per cent and 102+/-24 per cent respectively. Ejection fraction increased significantly during dobutamine infusion (maximal percentage change of 43+/-9 per cent) whereas the pre-ejection period (PEP) and the left ventricular ejection time (LVET) decreased significantly (maximal percentage change of -41+/-2 per cent and -28+/-3 per cent respectively). All these six indices were significantly correlated with each other. Conversely, the ratio PEP/LVET and the LVET corrected for heart rate dependency showed a maximal percentage change of only -10+/-1 per cent and -16+/-7 per cent, respectively, during the dobutamine infusion and were not significantly correlated with the other contractility indices. This study demonstrated the feasibility of the conductance method to determine cardiac contractility in conscious healthy dogs submitted to a pharmacological stress testing and provides control values for eight indices of left ventricular contractility during dobutamine infusion at increasing dosages.

Animals↗
PubMedDate not supplied

Extensive genetic diversity of Plasmodium falciparum isolates collected from patients with severe malaria in Dakar, Senegal.

While some genetic host factors are known to protect against severe Plasmodium falciparum malaria, little is known about parasite virulence factors. We have compared the genetic characteristics of P. falciparum isolates collected from 56 severe malaria patients and from 30 mild malaria patients recruited in Hôpital Principal, Dakar, Senegal. All isolates were typed using polymerase chain reaction amplification of polymorphic genetic loci (MSP-1, MSP-2, HRP1, GLURP, CSP, RESA, and the multigene family Pf60). The complexity of infections was lower in severe than in mild malaria and the parasite genetic diversity in both groups was very large. No specific genetic make-up was associated with severity; there were, however, marked differences in allele frequencies in both groups, with a prevalence up to 60% of MSP-2 alleles specifically observed in the severe malaria isolates. In addition, the presence of MSP-1/RO33 alleles was significantly associated with a higher plasma level of tumour necrosis factor alpha receptor 1 (P < 0.05), a reported indicator of severity in human malaria. These results point to potential differences in the genetic characteristics of parasites inducing severe versus mild pathology.

Adolescent↗
PubMedDate not supplied

[Results of the conservative surgical and irradiation treatment of 132 nonpalpable ductal carcinomas in situ of the breast].

PURPOSE: Retrospective analysis of results of treatment of 132 subclinical ductal carcinomas in situ, non-palpable. MATERIAL AND METHODS: Patients were treated with limited surgery and 70 Gy radiation therapy (70 Gy). RESULTS: With a median follow-up of 7 years, the total recurrence rate was 6%, and the actuarial rate at 5 years 4% and at 10 years 13% at. These have no influence on recurrence on the specific actuarial survival rate which was 100% at 10 years. In spite of five infiltrating recurrences of seven, no metastasis appeared 48 months after the salvage surgery. The global rate of breast preservation was 92% at 7 years. DISCUSSION AND CONCLUSION: Therapeutic indications were developed taking into account the present analysis and a literature review (2,338 in situ ductal carcinomas, palpable or not, treated with conservative surgery, with or without adjuvant radio-therapy).

Adult↗
PubMedDate not supplied

Steroid synthesis and metabolism in the nervous system: trophic and protective effects.

Steroids influence the activity and plasticity of neurons and glial cells during early development, and they continue to exert trophic and protective effects in the adult nervous system. Steroids are produced by the gonads and adrenal glands and reach the brain, the spinal cord and the peripheral nerves via the bloodstream. However, some of them, named "neurosteroids", can also be synthesized within the nervous system. They include pregnenolone, progesterone, dehydroepiandrosterone and their reduced metabolites and sulfate esters. Little is known concerning the regulation of steroid synthesis in the nervous system, which involves interactions between different cell types. For example, the synthesis of progesterone by Schwann cells in peripheral nerves is regulated by a diffusible neuronal signal. Neurotrophic and neuroprotective effects of steroids have been documented both in cell culture and in vivo. PROG plays an important role in the neurological recovery from traumatic injury of the brain and spinal cord by mechanisms involving protection from excitotoxic cell death, lipid peroxydation and the induction of specific enzymes. After transection of the rat spinal cord, PROG increases the number of nitric oxide synthase expressing astrocytes immediately above and below the lesion. PROG also plays an important role in the formation of new myelin sheaths. This has been shown in the regenerating mouse sciatic nerve after lesion and in cocultures of sensory neurons and Schwann cells. PROG promotes myelination by activating the expression of genes coding for myelin proteins. The modulation of neurostransmitter receptors, in particular the type A gamma-aminobutyric acid, the N-methyl-D-aspartate and the sigma 1 receptors, is involved in the psychopharmacological effects of steroids and allows to explain their anticonvulsant, anxiolytic, antidepressive and sedative effects as well as their influence on memory. Pregnenolone sulfate has been shown to reverse age-related deficits in spatial memory performance and to have protective effects on memory in different models of amnesia.

Animals↗
PubMedDate not supplied

Low-grade myxoid chondrosarcoma of the base of the skull: CT, MR, and histopathology.

A retrospective CT, MR, and histopathologic study was performed in five patients with histologically verified low-grade myxoid chondrosarcoma of the base of the skull. In four patients, the tumor originated off the midline and was associated with bone destruction at the petrous apex near the petrooccipital fissure. Tumor extent included the cerebellopontine angle in three patients and the parasellar area in two patients. The fifth tumor originated on the midline and was associated with destruction at the dorsum sellae. Three tumors contained calcifications, whereas two lesions were mostly isodense with brain on CT scan. All tumors were hypointense on T1-weighted MR images and very intense on T2-weighted images except for areas of signal void consistent with calcifications. Light microscopy revealed islands of mature hyaline cartilage in an abundant myxoid ground substance. Histology and immunocytochemical analysis were consistent with a low-grade myxoid chondrosarcoma. The CT and MR features of low-grade myxoid chondrosarcoma are comparable with those of chordoma. Chordoma usually arises from the midline, but cases with origin from the lateral portion of the clivus or the petrous apex have been described. Low-grade myxoid chondrosarcoma has distinct histologic and immunocytochemical features and includes lesions formerly called "chondroid chordomas."

Adolescent↗
PubMedDate not supplied

A comparison of topical mequitazine and disodium cromoglycate in allergic conjunctivitis induced by a specific conjunctival provocation test.

PURPOSE: Twenty-two people with a history of grass pollen allergic conjunctivitis were enrolled outside the pollen season in this study to compare the efficacy of 0.05% mequitazine eyedrops with topical 2% disodium cromoglycate. METHODS: This randomized, double-blind study compared right and left eyes. Subjects received 2% disodium cromoglycate eyedrops in one eye and mequitazine vehicle in the fellow eye 4 times daily for 4 days. For the last instillation, mequitazine vehicle was replaced by one drop of 0.05% mequitazine and 15 min later a conjunctival provocation test (CPT) with grass pollen was performed. RESULTS: The sum of the scores for hyperemia and itching, and total composite score were lower after 0.05% mequitazine than after 2% disodium cromoglycate (p < 0.0001 in each case). The allergen threshold dose which elicited a positive allergic response was higher in the mequitazine group (p < 0.001). Both treatments showed good tolerance upon instillation. No adverse events related to study treatment occurred. CONCLUSIONS: These results demonstrate the superior efficacy of a single drop of 0.05% mequitazine 15 min before CPT compared with 2% disodium cromoglycate 4 times daily for 4 days.

Administration, Topical↗
PubMedDate not supplied

In vivo voltammetry and microdialysis monitoring of monoamine metabolism in the rat brainstem neurons.

Two "in vivo" techniques allow the monitoring of extracellular levels of monoamines and related compounds in selected rat brainstem regions: voltammetry and microdialysis. "In vivo" voltammetry has a high regional selectivity: for example, we have been able to perform a subregional study and to show that the increase in extracellular DOPAC induced by 30 min-hypotension was twice as larg in the rostral as in the caudal rat locus coeruleus. The spatial resolution, as expressed by x 1/2 (see text), is 4 times better for voltammetry (50 microns) than for microdialysis (190 microns). Another advantage of voltammetry is its excellent time resolution. However, microdialysis has a much better biochemical specificity than voltammetry. Furthermore it allows some enzymatic activities, such as tyrosine hydroxylase, to be measured almost continuously in catecholaminergic brain nuclei. From a functional point of view, the results of our experiments (alpha 2 ligand administration, arterial hypotension or stress) illustrate the respective interest and complementarity of these two "in vivo" techniques. Their current developments will lead to a better temporal and biochemical resolution combined with an increase in the number of substances analyzed "in vivo", including peptides and nitric oxide.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

[Leishmaniasis and AIDS].

Explore the source record for details and available documents.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

[Hypothalamic astrocytoma presenting as obesity with hypogonadism].

We report herein a case of a 30 year old male patient who consulted for a long standing obesity since childhood. Clinical examination reveals the presence of hypogonadism and gynecomastia without galactorrhea. Endocrine assessment showed an hypogonadotrophic hypogonadism with a moderate insufficiency of the adrenocortical axis. Neuro-ophthalmological examination disclosed an inferior bitemporal quadranopsia. MRI showed an extra-axial suprasellar mass, lightly hypointense in T1 and hyperintense in T2. After craniotomy and conservative biopsy, pathological examination of the tumor showed regular cells surrounded with collagen and reticulin marked with immunoperoxidase against S100 protein and GFAP (glial fibrinolytic acidic protein) strongly suggesting the diagnosis of juvenile pilocytic astrocytoma.

Adult↗