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Biomedical subjects

F Lacaille

Publications and source records attributed to F Lacaille.

At least 55 records · Page 3Linked to original sources
PubMed1996

Magnetic resonance imaging for diagnosis of Shwachman's syndrome.

Shwachman's syndrome is a rare disease characterized by the association of chronic diarrhea due to exocrine pancreatic insufficiency, metaphyseal dysostosis, and neutropenia. The diagnosis requires demonstration of lipomatosis, or fatty replacement of the pancreas, which is the typical pathological feature of the disease. Magnetic resonance imaging (MRI) was performed in 13 patients with exocrine pancreatic insufficiency, 7 with Shwachman's syndrome, 2 with Pearson's syndrome, 1 with normal sweat test later diagnosed as cystic fibrosis, and 3 without identified syndrome, and in 7 control children. Ultrasonography in the patients did not differentiate between atrophy and lipomatosis and could not be performed in 3. MRI visualized the pancreas in all. The same image was noted in all patients with Shwachman's syndrome with a normal-sized or enlarged pancreas, a hyperintense signal on T1- and T2-weighted image, and a null signal on short time inversion recovery (STIR)-weighted image, characteristic of fat. In all other patients, the findings were very different: The pancreas was a small structure surrounded with fat. In 1 patient without identified syndrome, the pancreas appeared to be partially replaced with fat. MRI is an excellent imaging technique to correlate the nature of a tissue and its radiological representation, especially fat, which gives a very typical signal. In our brief series of patients with Shwachman's syndrome, MRI had 100% positive predictive value in demonstrating lipomatosis. In atypical cases of pancreatic insufficiency in which some of the clinical features of Shwachman's syndrome are absent. MRI is an invaluable aid in the diagnostic procedure.

Adolescent↗
PubMed1995

[Bile acids and their therapeutic use in children].

Bile acids are natural detergents and the end-products of cholesterol metabolism. Their functions are mostly digestive: induction of bile flow and solubilization of biliary and alimentary lipids. They circulate along the enterohepatic cycle, and probably also along a shorter route, the cholehepatic shunt. They are relatively hydrophobic and perpetuate or worsen the hepatic lesions when their excretion is impaired in cholestasis, because of their affinity for biological membranes. Their functions depend on their relative hydrophilicity and ionization, ie on their structure and state of conjugation. They have an immunosuppressive effect in vivo and in vitro. Ursodeoxycholic acid (UDC) is a hydrophilic bile acid used in chronic cholestatic diseases. Biological improvement has been proven in autoimmune cholangiopathies in adults, and cystic fibrosis-associated liver disease in children. Clinical studies are on the way for other indications. It is still too early to evaluate the long-term clinical benefits, eg the reduction in needs for liver transplantation. UDC acid may induce a bicarbonate-rich hypercholeresis through the cholehepatic shunt, that would explain its efficacy in cystic fibrosis. In disorders of bile acid synthesis or transport, it could shunt the enzymatic block, or reestablish the bile flow through its osmotic effect. Like other bile acids it interacts with membranes, and is thought to stabilize them. In chronic cholestasis it would protect the membranes against the adverse effect of non-excreted endogenous bile acids. This interaction can also explain its immunosuppressive effect, through non-specific inhibition of transmission at the cell surface. That would explain the preferential clinical efficacy of UDC in autoimmune cholestasis, and stimulate its evaluation in "immunological" indications, such as liver transplantation and hepatic graft versus host disease.

Adult↗
PubMed1995

Hepatic toxicity associated with 2'-3' dideoxyinosine in children with AIDS.

Among 34 children with AIDS enrolled in a trial with 2'-3' dideoxyinosine (ddI), six (aged 1-6 years) developed liver abnormalities within 2-18 months after institution of ddI. Two children died of fulminant hepatic failure (one had also an adenovirus infection), and four had a striking elevation of alkaline phosphatases (AP: 1120-7000 IU/L). All of them received sulfa drugs and antifungic treatment with ketoconazole or fluconazole. Three had a serology positive for hepatitis C virus. The evolution of liver enzymes following withdrawal and rechallenge with ddI in the children with elevated AP was an indication of drug-induced toxicity in two patients. In both of the others, readministration of ddI did not cause any subsequent problems. Liver histology in the patients with fulminant hepatitis showed an extensive hepatic necrosis. Liver biopsy done in two other patients revealed a mild granulomatous hepatitis in one and nonspecific changes (i.e., steatosis and a mild inflammation) in the other. Hepatic toxicity has been described with ddI and other nucleoside analogs in adult patients. These six children had many potential causes of liver disease. It may be that ddI is not hepatotoxic per se but that it precipitates liver disease in predisposed patients. We recommend that liver functions be carefully monitored when using this drug.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Cerebrospinal fluid penetration of amikacin in children with community-acquired bacterial meningitis.

The penetration of amikacin into the cerebrospinal fluid (CSF) was studied with 16 children (mean age, 1 year and 9 months; range, 4 months to 8 years) with community-acquired bacterial meningitis. Amikacin was given intravenously at a dose of 7.5 mg/kg of body weight twice daily. CSF was collected on day 1, at the expected peak concentration of amikacin in CSF. The mean (standard deviation) concentration of amikacin in CSF was 1.65 (1.6) mg/liter. Concentrations of amikacin in CSF correlated significantly with CSF glucose levels on admission. The mean concentrations of amikacin in CSF were 2.9, 1.1, and 0.20 mg/liter in patients with CSF glucose levels of < 1, 1 to 2, and > 2 mmol/liter, respectively. Thus, amikacin penetrates the blood-brain barrier substantially in children with bacterial meningitis and achieves particularly high concentrations when CSF glucose level is < 1 mmol/liter on admission.

Amikacin↗
PubMed1994

Concentrations of ceftriaxone in cerebrospinal fluid of children with meningitis receiving dexamethasone therapy.

The penetration of ceftriaxone into cerebrospinal fluid (CSF) was studied with 11 children (mean age: 2 years, 4 months; range: 4 months to 8 years) with meningitis, receiving dexamethasone (0.15 mg/kg of body weight intravenously four times daily) as adjunctive therapy. Ceftriaxone was given intravenously at doses of 50 mg/kg twice daily to patients < 18 months old and 100 mg/kg once daily to patients > or = 18 months old. CSF was collected after 1 day of treatment at the expected peak concentration of ceftriaxone in CSF. Concentrations of ceftriaxone in CSF ranged from 0.7 to 9.2 mg/liter, with a mean value of 4.0 (standard deviation [SD], 2.9) mg/liter. Values were significantly higher for patients with CSF glucose levels of < 1 mmol/liter on admission to the hospital than for patients with CSF glucose levels of > or = 1 mmol/liter (mean values of 7.1 [SD, 2.2] mg/liter versus 2.2 [SD, 1.1] mg/liter; P < 0.001). After 1 day of treatment, ceftriaxone concentrations in the CSF of children receiving dexamethasone are similar to the mean values reported for children not treated with dexamethasone.

Ceftriaxone↗
PubMed1993

Lipoprotein abnormalities associated with cholesteryl ester transfer activity in cystic fibrosis patients: the role of essential fatty acid deficiency.

The purpose of this study was to elucidate the roles of lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) in the lipoprotein derangement of cystic fibrosis (CF) patients with respect to their essential fatty acid (EFA) status. Triglyceride enrichment and cholesteryl ester (CE) depletion were observed in the lipoproteins of 22 CF patients. The abnormal chemical composition was more severe in 12 EFA-deficient (EFAD) than in 10 EFA-sufficient (EFAS) patients. Expressed in nmol.L-1.h-1, LCAT activity was higher (P < 0.05) in both EFAS (mean +/- SE, 92.7 +/- 1.9) and EFAD (108.8 +/- 3.0) patients than in control subjects (65.2 +/- 0.9). An equal CE transfer was recorded in the lipoprotein-deficient serum, as a source of CETP activity, in all groups studied by using normal exogenous low-density lipoprotein (LDL) and high-density lipoprotein (HDL). However, in contrast to the maximal amount of CE transferred from endogenous HDL to endogenous apolipoprotein B (apo B) in control subjects, a reduction in CETP activity was seen in CF patients and more pronounced in the EFAD group. These findings indicate that impaired lipoprotein composition may have marked effects on the transfer of CE between HDL and apo B in EFAD CF patients.

Adolescent↗
PubMed1993

Circulating tumor necrosis factor-alpha levels and lipid abnormalities in patients with cystic fibrosis.

Hyperlipidemia is prominent among the disturbances in intermediary metabolism that occur subsequent to infections by microorganisms. The response to such infections is known to involve several cell types and is mediated by cytokines. We hypothesized that metabolic lipid disturbances seen during infection in cystic fibrosis (CF) patients may partly be the result of excessive tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine known to cause a large spectrum of pathophysiologic alterations, including impaired lipid metabolism. Therefore, we determined the circulating concentration of TNF-alpha and analyzed its relationship to lipid and lipoprotein levels, as well as lipoprotein lipase activity, in 31 CF patients. Plasma TNF-alpha values were significantly (p < 0.01) elevated in patients with CF compared with controls. The CF subjects were found to have decreased plasma cholesterol (25%), LDL cholesterol (35%), and HDL cholesterol (19%) concentrations, whereas plasma triglycerides were significantly increased (p < 0.001). The apo A-I level was reduced (p < 0.005), whereas apo B levels were normal. Low levels of the major essential fatty acids were found in the plasma of the CF patients, and the triene/tetraene ratio confirmed their essential fatty acid deficiency. Postheparin lipolytic activity was lower in CF patients than in controls, and the decreased activity was accounted for primarily by a decline in hepatic lipase. A significant positive correlation (p < 0.001, r = 0.70) was found between TNF-alpha and plasma triglyceride levels. However, no association was noted between TNF-alpha and essential fatty acid, cholesterol, or lipoprotein cholesterol levels, or with lipoprotein lipase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The immunosuppressive effect of ursodeoxycholic acid: a comparative in vitro study on human peripheral blood mononuclear cells.

Ursodeoxycholic acid is an efficient treatment for putatively immune-mediated liver diseases, but its mechanism of action is unknown. We studied human mononuclear cell proliferation as an in vitro model for cell-mediated immunity in the presence of ursodeoxycholic acid, its glycoconjugate and tauroconjugate and chenodeoxycholic acid at concentrations of 5, 25 and 50 mumol/L. Proliferation was inhibited in a dose-dependent manner compared with control values (15% to 54% depending on the bile acid, concentration and mitogen used), except at 5 mumol/L where inhibition was significant with only one mitogenic stimulus of the three used. With one mitogen (phorbolester) the inhibition was additive with that of cyclosporine. The number of cell-surface receptors studied was not modified by bile acids. Interleukin-2 production was decreased 35% to 60% by ursodeoxycholic acid and its conjugates. The proliferation of the interleukin-2-dependent cell line CTLL-2 was also inhibited. The immunosuppression was reversible except at a chenodeoxycholic acid concentration of 50 mumol/L. Because bile acids are able to partition into membranes and change their properties, we speculate that this allows them to interact with cell-surface receptors or signaling systems within the membrane or on its inner face, thus impairing their function. This would inhibit the numerous extracellular messages that lymphocytes need to proliferate.

Animals↗
PubMed1991

Taurine decreases fecal fatty acid and sterol excretion in cystic fibrosis. A randomized double-blind trial.

Patients with cystic fibrosis may still have a significant degree of steatorrhea despite adequate pancreatic enzyme supplementation. Taurine is a conditionally essential amino acid that possibly improves the micellar phase of fat digestion. Thirteen children with cystic fibrosis and a significant degree of steatorrhea (> 13 g/d) were enrolled in a randomized double-blind crossover study of taurine (30 mg/kg per day) in contrast to placebo for two successive 4-month periods. No difference was noted in height and weight velocity, lung function, vitamin A level, and essential fatty acid status. Twelve of the 13 patients showed a decrease in fecal fatty acid excretion (26.5 +/- 2.6 g/24 h vs 15.4 +/- 2.5 g/24 h), affecting mainly saturates and monounsaturates, and a decrease in total sterol excretion (1492.6 +/- 303 mg/24 h vs 1211.7 +/- 213.8 mg/24 h) while ingesting taurine. Taurine may be a useful adjunct in patients with cystic fibrosis and severe steatorrhea.

Adolescent↗
PubMed1989

Accuracy of two wavelength pulse oximetry in neonates and infants.

In 60 neonates (gestational age, 26.5-40 weeks; postnatal age, 1-14 days) and in 11 infants (gestational age, 26-33 weeks; postnatal age, 4.5-38 weeks), the accuracy of two wavelength pulse oximetry was examined. A total of 112 comparisons between transcutaneous pulse oximetry saturation (StcO2, NELLCOR N-100) and arterial oxygen saturation (SaO2, OSM2 RADIOMETER) were obtained. SaO2 ranged from 80 to 100%. Criteria for comparison between StcO2 and SaO2 were standardized: patients in behavioral state 1, StcO2 stable for 2 min, and arterial samples drawn from an indwelling arterial line. StcO2 was significantly related to SaO2 (P less than 0.01), but the difference, StcO2 - SaO2, significantly increased when SaO2 decreased [StcO2 - SaO2(%) = -0.39 SaO2(%) + 37.95; r = -0.64, P less than 0.01]. No significant relationship was found between StcO2 - SaO2 and either bilirubinemia (range, 5-222 mumol/L) or fetal hemoglobin (HbF) (range, 12-95%). We conclude that StcO2 overestimates SaO2 when SaO2 decreases, and this overestimation is not due to high levels of bilirubin or HbF.

Bilirubin↗