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Biomedical subjects

P Hubert

Publications and source records attributed to P Hubert.

234 records · Page 13Linked to original sources
PubMed1978

Induction of maturation in Xenopus laevis oocytes by a steroid linked to a polymer.

A progesterone analog has been covalently linked via an amide bond to polyethylene oxide (molecular weight, 20,000). This macromolecular steroid molecule displays the biological activity of progesterone in inducing meiotic maturation when incubated with Xenopus laevis oocytes (stage VI) in vitro. Its efficiency (half-maximum effective concentration, 30 muM) is approximately 10 times lower than that of its low molecular weight homolog (3 muM). Control experiments with polyethylene oxide and an estradiol derivative (up to 1 mM) assessed the specificity of the progesterone macromolecular analog. Uptake experiments using radioactive derivatives revealed a small (if not negligible) intake of the macromolecular progesterone analog by the oocytes compared to that of free steroids, and no parallelism was found between radioactivity incorporation and effect. The possibility of cleavage of the macromolecular derivative during the incubation was ruled out. Furthermore, injection of the polymer-linked progesterone into the oocytes did not induce maturation. These observations suggest that the macromolecular progesterone analog itself is responsible for the biological effect and that the presence of this compound inside the cell is neither necessary nor sufficient for triggering reinitiation of meiosis. These conclusions are in agreement with the proposal that interaction with the plasma membrane of the oocyte is necessary for progesterone action in this particular system, in contrast to the case of somatic cells which have intracellular steroid receptors.

Animals↗
PubMed1978

Soluble biospecific macromolecule for purification of estrogen receptor.

An alternative to affinity chromatography purification of proteins based on the use of a water-soluble biospecific polymer has been applied to the estrogen receptor from calf uterus. The receptor (4S-trypsin form) was bound to a dextran-estradiol conjugate (molecular weight approximately 500,000) and the complex was isolated by gel filtration. Highly purified receptor was subsequently released from the dextran-estradiol conjugate by exchange with [3H]estradiol.

Animals↗
PubMedDate not supplied

Importance of the matrix and its chemical activation on the stability of immuno-adsorbents.

Various matrices were reacted with four different activation reagents, in order to prepare immuno-adsorbents for the selective removal of low-density lipoproteins from blood plasma of patients affected by hypercholesterolaemia. The resulting immuno-adsorbents were compared to that obtained earlier with cyanogen bromide activation, in terms of coupling yield, adsorption capacity and moreover stability towards the various chemical and biochemical conditions to which they are submitted during their handling. Tresyl chloride-activated Sepharose 6 Fast Flow turns out to afford optimal stability in the whole pH range tested.

Chromatography, Affinity↗
PubMedDate not supplied

Determination of meprobamate in pharmaceutical dosage forms also containing carbromal by liquid chromatography and indirect photometric detection.

In a pharmaceutical form also containing carbromal, meprobamate could not be quantified selectively by classical methods described in pharmacopoeias due to a significant interference from carbromal. Consequently, reversed-phase HPLC methods have been developed to separate the two active ingredients using indirect photometric detection to visualize and determine meprobamate which has very poor chromophoric properties. Different parameters influencing the sensitivity of the indirect response, such as the nature of the highly absorbing compound added to the mobile phase (the marker) as well as the methanol content and the pH of this phase, have been studied. Two chromatographic systems containing benzoic acid or cinnamic acid as the marker, have been optimized and validated. Good linearity and reproducibility have been obtained with both systems but the cinnamic acid method has the advantage that meprobamate and carbromal can be determined simultaneously at 273 nm.

Benzoates↗
PubMedDate not supplied

Factors influencing outcome after intestinal transplantation in children.

We evaluated 131 patients (6 months-14 years) who experienced 21 deaths before listing, 11 continuing on the waiting list, 38 well on home parenteral nutrition, 6 off parenteral nutrition and 59 transplanted (20 girls) aged 2.5 to 15 years, (18 >7 years). They received cadaveric isolated intestine (ITx, n = 31) or liver-small bowel (LITx, n = 32), including right colon (n = 43; 23 LITx) for short bowel (n = 19), enteropathy (n = 20), Hirschsprung (n = 14), or pseudo-obstruction (n = 6). Treatment included tacrolimus, steroids, azathioprine, or interleukin-2 blockers. After 6 months to 10.5 years, the patient and graft survivals were 75% and 54%. Sixteen patients (10 LITx) died within 3 months from surgery (n = 3), bacterial (n = 5) or fungal (n = 6) sepsis, or posttransplant lymphoproliferative disorder (n = 2). Rejection occurred in 27 patients, including 10 steroid-resistant episodes requiring antilymphoglobulins. The grafts were removed due to uncontrolled rejection in seven ITx recipients. Surgical complications were observed in 38 recipients (25 LSBTx) within 2 months, including bacterial (n = 22) or fungal (n = 11) sepsis, cytomegalovirus disease (n=12), adenovirus (n = 11), or posttransplant lymphoproliferative disorder (n = 12). Forty-two children (19 LSBTx) are alive. Weaning from parenteral nutrition was achieved after 42 days (median). Factors related to death or graft loss were pre-Tx surgery (P < .01), pseudo-obstruction (P < .01), age over 7 years (P < .03), fungal sepsis (P < .03), steroid resistant rejection (P < .05), hospitalized versus home patient (P < .01), and retransplantation (P < .05). Colon transplant did not affect the outcome. Interleukin-2 blockers improved isolated ITx (P < .05). Early referral and close monitoring of intestinal failure and related disorders are mandatory to achieve successful ITx.

Adolescent↗
PubMedDate not supplied

Selection and characterization of two specific monoclonal antibodies directed against the two variants of human herpesvirus-6.

Monoclonal antibodies (mAbs) specific for human herpesvirus-6 (HHV6) proteins were derived from the splenocytes of mice immunized with HHV6 TAN isolate-infected peripheral blood mononuclear cells. The two mAbs 8C8 and 7C7 reacted by means of immunofluorescence and immunoperoxidase assays with both variant A and variant B isolates giving two different staining patterns. In infected cells, cytoplasmic diffuse staining was observed with mAb 8C8, whereas intense nuclear staining was obtained with mAb 7C7. These different locations of viral target proteins were confirmed by confocal microscopy. The mAb 8C8 reacted with a family of six glycoproteins designated as the gp72 complex in the case of variant A strains and gp63 complex in the case of variant B strains. The endoglycosidases H and F reduced those glycoproteins to a putative precursor molecule of 58 kDa. The mAb 7C7 reacted with 116 and 109 kDa proteins with the two HHV6 variants. These two mAbs did not neutralize virion infectivity in the absence of complement. No cross-reactivity was observed when these mAbs were used in immunoperoxidase assay and immunoblotting against the proteins of human cytomegalovirus or other human herpesviruses. Thus, the two mAbs 8C8 and 7C7 may be valuable tools for the diagnosis and biological investigation of HHV6 infections.

Animals↗
PubMedDate not supplied

Intestinal transplantation in children: preliminary experience in Paris.

From November 1994 to November 1998, 20 children (2.5 to 14 years) received a jejunoileal graft alone (SBTx; n = 10) or in combination with the liver (SBLTx; n = 10 and/or the right colon (5 SBTx). Indications were intractable diarrhea of infancy (n = 8), short bowel syndrome (n = 6), extensive Hirschsprung disease (n = 4), and chronic intestinal pseudoobstruction (n = 2). Immunosuppression included tacrolimus, methylprednisolone, and azathioprine. Current follow-up ranges from 6 to 54 months. Five patients died (3 SBTx) within the first 2 months. Acute liver rejection occurred in 5 patients during the first 2 months. Sixteen episodes of intestinal rejection during the first 3 months in 11 patients (8 in 4 SBTx) were successfully treated in all but 3 by increasing tacrolimus dose and/or a 3-day methyprednisolone bolus or required antilymphoglobulins in 3 cases. Surgical complications occurred 8 times after SBLTx and 3 after SBTx. Infectious complications were more frequent in SBLTx recipients. Reversible Epstein-Barr virus-related posttransplant lymphoproliferative disease occurred in 3 recipients. Five presented cytomegalovirus infection. The SB graft was removed in 5 recipients (3 chronic rejection). All patients were started with oral and/or enteral feeding from the 7th postoperative day by using either normal food or protein hydrolysate diet. Currently, 10 of 11 children (8 SBLTx) achieved digestive autonomy after 5 to 30 weeks. All recipients gained weight; however, growth velocity remained reduced during the first 6 months because of the steroid therapy. Overall graft and patient survival is higher after SBLTx. Intestinal transplantation is indicated for patients with permanent intestinal failure. However, because parenteral nutrition is generally well tolerated, even for long periods, each indication for transplantation must be weighed carefully in terms of risk and quality of life.

Adolescent↗
PubMedDate not supplied

Determination of alpha-solanine and alpha-chaconine in potatoes by high-performance thin-layer chromatography/densitometry.

A high-performance thin-layer chromatographic (HPTLC) method was used to determine the glycoalkaloids alpha-solanine and alpha-chaconine in potatoes. Alpha-solanine and alpha-chaconine are extracted from dehydrated potatoes with boiling methanol-acetic acid (95 + 5, v/v). The analytes are separated on a Silica Gel 60 F254 HPTLC plate by a saturated mixture of dichloromethane-methanol-water-concentrated ammonium hydroxide (70 + 30 + 4 + 0.4, v/v), which is used for vertical development of the plate up to a distance of 85 mm. For visualization, the plate is dipped 3 times into a modified Carr-Price reagent, 20% (w/v) antimony(III) chloride in acetic acid-dichloromethane (1 + 3, v/v), and subsequently heated on a hot plate at 105 degrees C for 5 min. The glycoalkaloids all appear as red chromatographic zones on a colorless background. Densitometric quantification is performed at 507 nm by reflectance scanning. After determination of the appropriate response function, the proposed method was validated. Good results with respect to linearity, accuracy, and precision were obtained in the concentration range studied.

Algorithms↗
PubMedDate not supplied

[Therapy of severe asthma crisis in children. Therapeutic course. A propos of 40 cases].

Forty children with severe asthma were admitted to an intensive care unit from 1970 to 1981. Criteria of severity were alteration of consciousness, circulatory failure, hypercarbia greater than 7 KPa and paradoxical pulse greater than 35 mmHg persisting in spite of correct treatment. Some therapeutic measures (oxygen, corticosteroids, antibiotics, hydratation) were not modified during this period. On the contrary, bronchodilators, used at a higher dose since June 1980, were very effective on bronchospasm without side effects, making controlled ventilation unnecessary. These results seem to be very encouraging but have to be confirmed.

Adolescent↗
PubMedDate not supplied

[Acute cerebral edema complicating therapy for diabetic ketoacidosis in children ].

Cerebral edema complicating treatment of diabetic ketoacidosis does not seen to be very rare. This neurologic complication, which was observed in 3 cases, presents similarly in all patients, occurs mainly in children and adolescents and is usually lethal. Its mechanism has not been clearly explained yet. Various etiologic factors have been considered; sodium depletion, rapid infusion of hypotonic solutions and rapid fall of plasma glucose level might have a deleterious effect. On the basis of these data, some preventive therapeutic measures are proposed.

Blood Glucose↗
PubMedDate not supplied

Macrophage activation syndrome and rheumatic disease in childhood: a report of four new cases.

A macrophage activation syndrome (MAS) developed in four children with chronic rheumatic diseases. The presentation included fever, hepatic and splenic enlargement, profound depression of blood counts, lowering of ESR, elevation of SGOT/PT and hypofibrinogenemia. The most characteristic sign of MAS was the presence in the bone marrow aspirate of well differentiated macrophages showing active haemophagocytosis with haematopoietic elements in their cytoplasm. Activation of the macrophage was also illustrated by high levels of monokines in the serum of 2 patients. This immuno-hematological process of unknown etiology can be triggered by ubiquitous events such as infections and treatment with anti-inflammatory drugs. It is a potentially lethal complication which should be diagnosed rapidly, since administration of high-dose steroids with discontinuation of potentially toxic drugs can induce remission. Cyclosporin A was effective in two patients and may be of value in the management of the macrophage-activation syndrome. Its efficacy supports the central involvement of a T-cell dysfunction. It must be borne in mind that children with rheumatic diseases, especially the systemic form of juvenile chronic arthritis, are highly vulnerable to life-threatening macrophage activation, which appears to be more frequent than previously recognized. Very careful monitoring of apparently "innocent" drugs and intercurrent viral infections is thus required.

Adult↗