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Biomedical subjects

D Briand

Publications and source records attributed to D Briand.

At least 19 recordsLinked to original sources
PubMed2002

Characterisation of thermoluminescent LiF:Mg,Ti (MTS-N) detectors in the 85-550 K temperature range.

Miniature LiF:Mg,Ti (MTS-N) pellets, specially designed for dosimetry in proton radiotherapy, were studied in the 85-550 K temperature range. TL glow curves for differently Mg- or Ti-doped detectors were recorded, showing the preponderant influence of Mg concentration on the intensity of peak 5. The presence of a three-peak complex was also confirmed near 140 K; spectral emission of this peak consists of two bands whose maxima occur at 290 and 420 nm. TSEE glow curves above 300 K similar to those of TL were observed. The behaviour of TSEE and TL peak 5 following an X ray exposure from 33 to 500 Gy was studied: its intensity is a linear function of air kerma in both cases.

Fluorides↗
PubMed2002

Thermoluminescent properties of Ni and Co doped synthetic, high pressure, high temperature diamonds: application to ionising radiation dosimetry.

An investigation of the thermoluminescence (TL) properties of high pressure, high temperature (HPHT) synthetic diamond crystals grown under diluted nickel or cobalt as solvent catalysts is reported. After a study of TL properties of 6 different samples, it is shown that a crystal grown with Ni+2%Ti and annealed at 2100 K presents an intense glow peak at around 490 K. This peak is characterised by a broad emission band centred at 530 nm (2.34 eV). This crystal presents a significant, reproducible and linear TL response relative to the absorbed dose up to an X ray air kerma of 10 Gy. All these features make this material suitable for ionising radiation dosimetry. A similar study is made on another crystal grown from pure Co, and a comparative review of the results does show that for dosimetry work, Ni-containing diamonds are more appropriate than those grown from Co catalyst.

Cobalt↗
PubMed2002

On the luminescence properties of CaSO4:Ce.

The luminescent properties of cerium doped calcium sulphate are studied: fluorescence and excitation spectra, optical absorption and thermoluminescence (TSL). It is known that, in rare earth doped CaSO4, only cerium induces a strong 400 degrees C TSL peak. In CaSO4:0.2%Ce samples synthesised under oxidising conditions, the recovery step of Ce3+ fluorescence is correlated with the 400 degrees C TSL peak readout, as mentioned by Nair er al. Our results indicate that an oxidation of Ce3+ ion does occur under X-irradiation (Ce3+ --> Ce4+), followed by a complete return to the trivalent state after thermal annealing at about 500 degrees C; our results confirm the hypothesis of Nair et al that Ce3+ ions are oxidised by ionising irradiation. So, a pure redox reaction seems the most probable for the 400 degrees C TSL peak of CaSO4:Ce. Moreover, the use of the 400 degrees C TSL peak for high temperature dosimetry applications is discussed.

Calcium Sulfate↗
PubMed1998

Differential inhibitory effects of three nitric oxide donors on ornithine decarboxylase activity in human colon carcinoma cells.

Ornithine decarboxylase (ODC, EC 4.1.1.17) is the enzyme responsible for the synthesis of polyamines, which are absolutely necessary for cell proliferation. In the present work, we tested the effects of 3 nitric oxide (NO) donors, namely, sodium nitroprusside (SNP), (Z)-1-(N-methyl-N-[6-(N-methylammoniohexyl)amino] diazen-1-ium-1,2-diolate (MAHMA/NO) and 1,1-diethyl-2-hydroxy-2-nitroso-hydrazine sodium (DEA/NO), on ODC activity in human-colon carcinoma cells (HT-29). SNP was the most effective inhibitor of ODC activity with a concentration of 8 micromol/L inducing 50% inhibition of basal activity. The effect of SNP was reversed by haemoglobin (Hb), but not by GSH or L-cysteine (CYS). Very little of the SNP in solution was degraded into nitrite, but the presence of cellular homogenate increased the production of nitrite. MAHMA/NO and DEA/NO were much less effective than SNP as ODC inhibitors, since the concentrations of these agents which induce 50% inhibition of basal activity were 20- to 60-fold higher than that of SNP. The effects of MAHMA/NO and DEA/NO were not reversed by haemoglobin. In solution, these latter 2 agents were totally degraded into nitrites. In conclusion, SNP on the one hand and MAHMA/NO and DEA/NO on the other appeared to release different NOx species with different efficiency on ODC activity.

Dose-Response Relationship, Drug↗
PubMed1995

Functioning and regioselectivity of the lipase of Candida parapsilosis (Ashford) Langeron and Talice in aqueous medium. New interpretation of regioselectivity taking acyl migration into account.

The lipase of Candida parapsilosis catalyses the formation of esters in aqueous media. In addition, the hydrolytic activity of the enzyme has been described in a recent publication as being selective for the 2 position, which is extremely rare. These features led to deeper investigation of the functioning and regioselectivity of the lipase in a biphasic aqueous medium. It is shown that, in addition to hydrolysis, the lipase of C. parapsilosis catalyses an alcoholysis reaction in the strict sense of the term, i.e. the transfer of fatty acyls groups from acylglycerols to various alcohols without direct involvement of water. In the presence of alcohol in the aqueous medium, alcolysis occurred preferentially to hydrolysis. The enzyme thus displays transferase activity in which the acyl acceptor may be either water or alcohol. This activity is not stereospecific to either the acyl donor or acceptor. Hydrolysis and alcoholysis of monooleoylglycerols, dioleoylglycerols and trioleoylglycerols were studied successively. Investigation of the regiospecificity of alcoholysis in the presence of the lipase of C. parapsilosis showed that the selectivity of hydrolysis for the 2 position was, in fact, only apparent. In certain cases, and particularly when the initial substrate was a triacylglycerol, the similtaneous functioning of the two hydrolysis and alcoholysis reactions led to the appearance of equivalent quantities of 1,2(2,3)-diacylglycerol and 1,3-diacylglycerol in the reaction mixture; this proportion might then be interpreted as the result of selectivity of the hydrolysis reaction for position 2 of the triacylglycerol.

Alcohols↗
PubMed1995

Pharmacokinetic parameters of antipyrine in dog after hepatectomy.

Pharmacokinetic studies with antipyrine were carried out on beagle dogs to determine the consequence of hepatectomy on hepatic drug metabolizing capacity, the rate of hepatic regeneration, and the possible beneficial effect of hepatocellular transplantation. The drug (250 mg) was administered by short IV infusion in three groups of dogs (first group, 65% hepatectomy; second group, 65% hepatectomy with hepatocyte transplantation; third group 80% hepatectomy). Pharmacokinetic parameters of antipyrine were evaluated before surgery and within 10 d after surgery. Blood samples were taken at frequent intervals after drug administration and antipyrine was assayed in plasma by a specific HPLC method with UV detection. Before surgery, the mean elimination half-life was about 1.1 h and total clearance averaged 6 L h-1. In dogs with 65% hepatectomy, no statistical differences in pharmacokinetic parameters of antipyrine appeared before or after surgery. When 65% hepatectomy was associated with hepatocyte transplantation, a significant increase in elimination half-life and a significant decrease in total clearance were observed. The same statistical differences in the pharmacokinetic parameters were observed in the group with 80% hepatectomy. Transplantation of isolated hepatocytes into the spleen did not correct hepatocellular insufficiency. In this study, numerous laboratory tests were performed. A significant correlation was found between serum albumin, cholesterol, factor V, ALAT, total bilirubin, and ratio of amino acids and the pharmacokinetic parameters of antipyrine.

Alanine Transaminase↗
PubMed1995

Substrate specificity of the lipase from Candida parapsilosis.

Substrate specificity of the acyltransferase activity of the lipase (EC 3.1.1.3) from Candida parapsilosis CBS 604 was studied in aqueous media. The specificity toward both acid and alcohol parts of a large number of acylglycerols and aliphatic esters was investigated. This lipase showed a high activity in the presence of esters with long-chain fatty acids and particularly unsaturated fatty acids with a cis-delta 9 double bond. It was observed that the activity profile depended not only on the alcohol part of the acyl ester, but also on the temperature of the reactant medium. The best lipid substrates had their melting point between -40 to +20 degrees C, 14 to 18 carbon atoms in the acyl group and 1 to 4 carbon atoms in the alkyl group. The enzyme, defined as an acyltransferase in a previous paper, showed a high affinity for primary and secondary alcohols with a short carbon chain (1 to 5 carbon atoms) as acyl acceptors. The influence of free alcohols in the reactant medium on the hydrolysis and alcoholysis activities of the enzyme is discussed. Two phenomena seem to be involved, depending on the alcohol: competition with water for the acyltransfer reaction and lipid substrate dilution when the alcohol places at the oil/water interface.

Alcohols↗
PubMed1994

Repeated hepatic resections for liver metastases from colon carcinoma. Montpellier Cancer Institute experience.

The main cause of death after hepatic resection for colorectal liver metastases is tumor recurrence. An improvement in survival may be achieved by resection of recurrent hepatic metastases as previously reported. In this paper we report our experience with 13 repeated liver resections in 11 patients. The post-operative mortality was 8% and the morbidity was 23% with two biliary tract fistulas and one recurrent pleural effusion. The median survival time from the first hepatic resection was 23 months, but differed according to the length of the disease-free interval (more than 1 year and less than 1 year: 49 and 17 months, respectively (P < 0.05). Our results suggest that repeated hepatic resection is technically a safe procedure and may be beneficial to selected patients. All candidates should be carefully evaluated pre-operatively for extrahepatic disease.

Adult↗
PubMed1993

Treatment of fistulas of the gastrointestinal tract with total parenteral nutrition and octreotide in patients with carcinoma.

The development of a fistula is a serious postoperative complication. Conservative medical treatment with total parenteral nutrition, skin care and intensive infection control usually succeeds in closing fistulas (60 to 75 percent), but the treatment is of long duration (two to three months), high cost and high morbidity related to prolonged hospitalization. We have used octreotide, a long half-life stomatostatin analog, in 40 patients from two European university centers with postoperative enterocutaneous fistulas. Twenty-two patients had low fistula output and 28 patients had high fistula output. Spontaneous closure was achieved in 77.5 percent of the patients after a mean of 13.6 days. One patient died. Glucose intolerance, which has been reported with stomatostatin treatment of fistulas, was not observed. Previous chemotherapy or radiotherapy or low albumin level (23 grams per deciliter) negatively influenced fistula closure. As an adjunct treatment to primary care (total parenteral nutrition, skin care and infection control), octreotide is efficient in reducing fistula output and accelerating spontaneous fistulas closure.

Adult↗
PubMed1992

Plasma and jejunal glutamine levels after extensive small bowel resection in dogs.

Recent studies have demonstrated that glutamine may be required for mucosal growth and that it is widely utilised by the intestinal tract after surgery. This study has evaluated the effect of massive small bowel resection on plasma and jejunal glutamine and related amino-acids level evolution after surgery. Transection was performed in 6 dogs (control group) and enterectomy in 10 dogs leaving 25cm of jejunum, associated with colectomy (group 1). Plasma glutamine levels decreased on D2 (p = 0.03) in the resected group while a significant decrease of plasma alanine levels was observed on D2 (p = 0.002), D4, D6 and D8 (p < 0.001). Intestinal mucosa glutamic acid content was increased on D8 in this group (p < 0.001). No changes were observed in the control group. These results suggest that glutamine is a required substrate after massive small bowel resection which could improve the intestinal adaptation encountered after enterectomy.

Journal Article↗
PubMed1991

Autotransplantation of the pylorus sphincter at the terminal abdominal colostomy. Experimental study in dogs.

A method for constructing a continent colostomy has been tried in dogs. The pylorus sphincter with blood supply by the left gastroepiploic vessels was transposed around or anastomosed to the terminal abdominal colostomy in five dogs. One dog had a colostomy without pylorus transplantation. Evaluation was by clinical (consistency and weight of fecal material and number of defecations per day), radiologic, and manometry studies. There was no difference in the clinical data. In all the dogs, the radiologic study demonstrated emptying of the contrast medium to the peristomal skin. By manometry one high-pressure zone was demonstrated, and, in all dogs with a transposed or anastomosed pyloric segment, the average resting pressure was superior to that of the control dog. However, the transposed pylorus sphincter alone was not sufficient to control continence.

Animals↗
PubMed1990

The thumb and index finger as principal surgical instruments to secure the inferior vena cava between the liver and the diaphragm in routine operations of the liver.

Presented herein is a simple and safe technique to secure the IVC in its segments above the liver and below the diaphragm through a simple incision in the abdomen. After complete division of the hepatic ligaments, the index finger is passed through the upper recessus of the lesser sac, behind the vein, and just above the caudate lobe, meeting the right thumb on the right side of the vein. A tissue string is then passed, and the IVC is secured. The experience of the authors with more than 100 consecutive hepatectomies has shown this technique to be a reliable approach to secure the IVC during routine hepatic operations.

Diaphragm↗
PubMedDate not supplied

Comparison of two methods of autologous intrasplenic hepatocellular transplantation in partially hepatectomized dogs.

Autologous hepatocellular transplantation using reflux into the spleen via the venous tributaries was compared in 65% hepatectomized dogs to direct injection into the splenic pulp. Transplantation into the spleen via the inferior terminal polar splenic vein led to a better survival rate (50 vs. 0%). Hepatocytes embolization to the intrahepatic portal vein system was observed. Although hepatocyte transplantation into the spleen can be accomplished either by direct punction of the spleen or by retrograde injection into a splenic vein, the second method decreases the frequency of cell embolization.

Animals↗
PubMedDate not supplied

Influence of N-acetylglutamine or glutamine infusion on plasma amino acid concentrations during the early phase of small-bowel adaptation in the dog.

Glutamine is a nonessential neutral amino acid that is widely consumed by the intestinal tract in catabolic states. We have followed up the plasma amino acid profile after extensive small-bowel resection in dogs receiving total parenteral nutrition (TPN) with or without glutamine (GLN) or N-acetylglutamine (aGLN) supplementation. Animals were divided into four groups according to the type of surgery (enterectomy or transection) and nutrition (TPN, TPN with aGLN, or TPN with GLN). Plasma GLN levels decreased in group I (enterectomy and TPN) on day 2 (p = .03) and significantly increased on postoperative days in groups III (enterectomy and TPN with aGLN) and IV (enterectomy and TPN with GLN). A significant increase of plasma GLN was observed in groups III and IV compared with group I on days 6 and 8 (p = .03 and p = .01). Plasma alanine decreased in groups with bowel resection, whereas no change was observed in the control group (transection) and the decrease of plasma alanine was significantly less pronounced in groups III and IV compared with group I. The increase of crypt depth and villous height was more pronounced in groups III and IV. These results suggest that GLN is a required substrate for mucosal growth and function, which could improve the intestinal adaptation encountered after enterectomy.

Alanine↗
PubMedDate not supplied

[Short bowel syndromes in adults. Prognostic factors. Evaluation and treatment. Retrospective study. Apropos of 80 cases].

Since 1981, a consensus is appeared in order to define and to precise the natural evolution of short bowel with a maximal remaining small bowel of 150 cm. The phenomenon of intestinal adaptation which are better known in animals than in humans, are on the dependence of luminal, hormonal and humoral factors (epidermal growth factor, polyamines). The knowledge of prognostical factors and the anatomical and functional evaluation of remaining small bowel allow to "measure" the improvement of digestive absorption and to decide the duration of nutritional support. An experience in 80 cases of short bowel syndrome is reported. A significant correlation exists between the duration of parenteral nutrition support and the length of the remaining gut (p < 0.001) and multifactorial analysis differentiates 3 groups of short bowel characterized by their length and parenteral support duration.

Adult↗
PubMedDate not supplied

[Liver tumors around the vena cava. Strategy for surgical approach of segments I and IX].

The technical problems raised by the delicate surgery of tumours of the liver developing around the vena cava, with and without invasion of segments I and IX was studied on the basis of 7 cases reports. The intra- or extra-hepatic pedicule route, the denudation of the entire retrohepatic vena cava, and the clamping needed for exsanguinous surgery are presented together with future perspectives including 3-D liver imaging, stimulation of liver regeneration potential and ex-vivo techniques are discussed with the aim of more and more carcinological liver surgery.

Aged↗