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Biomedical subjects

D Phaneuf

Publications and source records attributed to D Phaneuf.

16 recordsLinked to original sources
PubMed1992

Type 1 hereditary tyrosinemia. Evidence for molecular heterogeneity and identification of a causal mutation in a French Canadian patient.

Type 1 hereditary tyrosinemia (HT1) is a metabolic disorder caused by a deficiency of fumarylacetoacetate hydrolase (FAH). Using a full-length FAH cDNA and specific antibodies, we investigated liver specimens from seven unrelated HT1 patients (six of French Canadian and one of Scandinavian origin). The expression of FAH in livers of these individuals was analyzed at several molecular levels including mRNA, immunoreactive material (IRM), and enzymatic activity. Four phenotypic variants were differentiated by these assays: (i) presence of FAH mRNA without any IRM or enzymatic activity, (ii) decreased FAH mRNA, IRM, and enzymatic activity, (iii) moderately decreased FAH mRNA and IRM with severely reduced enzymatic activity, and (iv) undetectable FAH mRNA, IRM, and enzymatic activity. These various molecular phenotypes suggest that this disorder may be caused by a variety of FAH mutations. Interestingly, we found no apparent relationship between the clinical and the molecular phenotypes, except that patients with absent IRM and enzymatic activity tend to have higher levels of serum alpha-fetoprotein and an earlier clinical onset. To further analyze the molecular basis of HT1, the FAH cDNA of a patient designated as variant A was amplified and sequenced. An A-to-T transversion, which substitutes asparagine16 with isoleucine (N16I), was identified. This patient was heterozygous as shown by direct sequencing of the amplified region and hybridization with allele-specific oligonucleotide probes. The N16I allele originates from the father and the second allele appears not to be expressed in the liver of the proband. CV-1 cells transfected with the mutant cDNA produced FAH mRNA, but no protein or hydrolytic activity, as predicted by the "A" phenotype of the patient. This is the first demonstration of heterogeneity in the expression of FAH at the levels of protein, mRNA, and enzymatic activity in the livers of HT1 patients and is the first identification of a causal mutationin this disease.

Adolescent↗
PubMed1991

Cloning and expression analysis of a cDNA encoding fumarylacetoacetate hydrolase: post-transcriptional modulation in rat liver and kidney.

Fumarylacetoacetate hydrolase (FAH) is an enzyme which is deficient in human hereditary tyrosinemia type 1. We have cloned and sequenced a rat liver cDNA encoding FAH. The identity of the clone was ascertained by hybrid-selection experiments and deduced amino acid (aa) sequence homologies with sequenced oligopeptide fragments of the purified rat liver protein. The cDNA codes for a 419-aa protein of 45,946 daltons. We used this cDNA as a probe in conjunction with a specific anti-rat FAH antibody to study the expression pattern of the FAH gene in rat liver and kidney. Northern blot analysis indicates that the kidney contains slightly more FAH mRNA that the liver. Western blotting shows, however, that the liver contains about twice as much FAH protein as the kidney. Primer extension experiments suggest that there are no differences in the 5'-untranslated (UT) ends of the FAH mRNA of both tissues. We conclude that synthesis of the FAH protein is in part regulated at the post-transcriptional level in rats liver and kidney, and that this regulation does not appear to be mediated by the 5'-UT sequence of the FAH mRNA.

Amino Acid Sequence↗
PubMed1991

Enalapril versus digoxin in patients with congestive heart failure: a multicenter study. Canadian Enalapril Versus Digoxin Study Group.

Patients with New York Heart Association functional class II or III heart failure stabilized on furosemide therapy were entered into a randomized controlled trial comparing enalapril (n = 72) and digoxin (n = 73). End points were clinical outcome, treadmill exercise capacity and echocardiographic left ventricular dimensions. Improvement in clinical outcome was defined as a reduction of at least one functional class or withdrawal because of an adverse clinical event. After 4 weeks, 13 patients receiving enalapril showed improvement, 55 had no change and 9 manifested deterioration compared with 7, 49 and 17, respectively, in the digoxin group (p less than 0.01). After 14 weeks, 13 patients receiving enalapril showed improvement, 50 had no change and 9 manifested deterioration, compared with 14, 37 and 22, respectively, in the digoxin group (p less than 0.025). More patients in the digoxin group were withdrawn because of an adverse clinical event (p less than 0.05). Exercise time and percent fractional shortening improved in both groups (p less than 0.001 and less than 0.05, respectively), with no significant difference between groups (p greater than 0.50). Both rate-pressure product and subjectively evaluated exertion during submaximal exercise were reduced only in the enalapril group. Although the majority of patients in both groups did well, those receiving enalapril experienced fewer adverse clinical events and had less fatigue during submaximal exercise.

Adult↗
PubMed1991

Cloning and expression of the cDNA encoding human fumarylacetoacetate hydrolase, the enzyme deficient in hereditary tyrosinemia: assignment of the gene to chromosome 15.

Type 1 hereditary tyrosinemia (HT) is an autosomal recessive disease characterized by a deficiency of the enzyme fumarylacetoacetate hydrolase (FAH; E.C.3.7.1.2). We have isolated human FAH cDNA clones by screening a liver cDNA expression library using specific antibodies and plaque hybridization with a rat FAH cDNA probe. A 1,477-bp cDNA was sequenced and shown to code for FAH by an in vitro transcription-translation assay and sequence homology with tryptic fragments of purified FAH. Transient expression of this FAH cDNA in transfected CV-1 mammalian cells resulted in the synthesis of an immunoreactive protein comigrating with purified human liver FAH on SDS-PAGE and having enzymatic activity as shown by the hydrolysis of the natural substrate fumarylacetoacetate. This indicates that the single polypeptide chain encoded by the FAH gene contains all the genetic information required for functional activity, suggesting that the dimer found in vivo is a homodimer. The human FAH cDNA was used as a probe to determine the gene's chromosomal localization using somatic cell hybrids and in situ hybridization. The human FAH gene maps to the long arm of chromosome 15 in the region q23-q25.

Amino Acid Sequence↗
PubMed1989

Clindamycin with primaquine for Pneumocystis carinii pneumonia.

Combined therapy with clindamycin and primaquine was used in twenty-eight episodes of Pneumocystis carinii pneumonia in 25 patients, of whom 17 had been unresponsive or intolerant to conventional treatment and 8 were being treated for the first time. The treatment was effective in all but two episodes, the main adverse reaction being a generalised maculopapular rash.

Administration, Oral↗
PubMed1985

Effect of aminoglycosides on the disposition of thyroid hormones and thyroglobulin.

Our study was designed to confirm the potential effects of three aminoglycosides on the disposition of thyroid hormones. Twenty-seven patients diagnosed with either cellulitis (n = 19), chronic osteitis (n = 4), or an abscess (n = 4) were selected. Thirteen patients received tobramycin, 60 to 100 mg iv q. 8 h., plus cloxacillin, 1 gm iv q. 4 h.; seven patients received netilmicin, 40 to 120 mg iv q. 8 h., plus cloxacillin, 1 gm iv q. 4 h.; and seven patients received either cloxacillin, 1.5 gm iv q. 4 h., or cefoperazone, 2 to 4 gm iv q. 12 h. for at least 7 days. Another group of six normal subjects received neomycin, 0.5 gm po q. 6 h. for 7 days. All these subjects had normal thyroid function before antibiotic dosing and none had thyroid function abnormalities. Tobramycin and cloxacillin/cefoperazone did not influence thyroid function. Netilmicin decreased the total serum concentrations of triiodothyronine (T3) from 114 +/- 9 to 75 +/- 7 ng/dl (P less than 0.01), probably because of increased clearance, as the T3 free fraction increased from 0.43% +/- 0.02% to 0.49% +/- 0.02% (P less than 0.05). Thyroxine (T4) and reverse T3 (rT3) levels were not affected. Neomycin decreased T3 levels from 104 +/- 8 to 92 +/- 7 ng/dl (P less than 0.05) and the serum concentrations of thyroglobulin from 17.3 +/- 2.0 to 11.7 +/- 2.0 ng/ml (P less than 0.001). Because T4 and rT3 levels did not change, our results suggest that neomycin may have directly affected the gland. We conclude that some aminoglycosides can alter the disposition of thyroid hormones.

Adult↗
PubMed1985

Aztreonam: correlation between disk diffusion and agar plate dilutions susceptibility tests.

Regression lines and error rate-bounded analyses were performed for correlating inhibitory zone diameters with the 30-micrograms aztreonam disk and aztreonam minimal inhibitory concentration for gram-negative aerobic clinical isolates. A correlation coefficient of -0.81 was found for the regression line. Preliminary proposed criteria to distinguish susceptible isolates from resistant ones are: susceptible greater than or equal to 22 mm (MIC less than or equal to 8 micrograms/ml), intermediate 16-21 mm (MIC = 16 micrograms/ml) and resistant less than or equal to 15 mm (MIC greater than or equal to 32 micrograms/ml). Using these criteria, the rates for false-susceptible and false-resistant isolates were zero.

Agar↗
PubMed1979

Agar disk diffusion susceptibility characteristics of azlocillin, carbenicillin, mezlocillin, piperacillin, and ticarcillin.

The agar disk diffusion susceptibility of Enterobacteriaceae to mezlocillin and piperacillin was correlated with agar minimal inhibitory concentrations and compared with the susceptibility to carbenicillin. The agar disk susceptibility of Pseudomonas aeruginosa to azlocillin, mezlocillin, and piperacillin was correlated with agar minimal inhibitory concentrations and compared with the susceptibility to carbenicillin and ticarcillin. Criteria are offered for the zones of inhibition to provide information about resistant and susceptible isolates that correlate with known serum levels.

Carbenicillin↗
PubMed1977

Difference in the distribution of e antigen among different ethnic groups in a population of blood donors.

Sensitive techniques were used to detect e antigen and the corresponding antibody (anti-e) among 368 voluntary blood donors positive for hepatitis B surface antigen in the Montreal area and 310 people living in close contact with them. Neither e nor anti-e was found in the absence of markers of hepatitis B virus (HBV). Among the blood donors e antigen was detected in 23 and anti-e in 313, and 32 were negative for both markers. Of the 368 blood donors 330 were of French origin and 38 from other ethnic groups. The 23 e-positive subjects were unequally distributed among the ethnic groups: only 14 (4.2%) were recruited among the French group while 9 (23.7%) were recruited among other ethnic groups (P less than 0.001). This differences among ethnic groups might be related to the vertical or horizontal mode of dissemination of HBV infection.

Antigens↗