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Biomedical subjects

M Beaulieu

Publications and source records attributed to M Beaulieu.

At least 37 records · Page 2Linked to original sources
PubMed1997

Isolation and characterization of UGT2B15(Y85): a UDP-glucuronosyltransferase encoded by a polymorphic gene.

Genetic polymorphisms occur in many of the drug metabolizing enzymes. However, the effect of polymorphisms in the genes encoding phase II drug metabolizing UDP-glucuronosyltransferases is still undescribed, despite the many reported cases of variations in glucuronidation activities. Characterization of the UGT2B15(Y85) cDNA, which was isolated from human prostate and LNCaP cell cDNA libraries, revealed 20 nucleotide differences between UGT2B15(Y85) and the previously characterized UGT2B15 protein UGT2B15(D85). However, only one of the two variations in the coding region leads to an amino acid change from aspartic acid to a tyrosine residue at position 85. The genomic DNA of 27 subjects were analysed by direct sequencing of polymerase chain reaction (PCR) products and demonstrated that UGT2B15(D85) and UGT2B15(Y85) are encoded by variant alleles prevalent in the Caucasian population. Expression of UGT2B15(D85) and UGT2B15(Y85) in HK293 cells demonstrated similar substrate specificities. Of the 65 potential substrates tested for activity, the proteins were active on phenolic compounds, coumarins, flavonoids, drugs and steroid hormones. Both proteins displayed similar Km values of 2.2 and 2.4 microM for androstane-3alpha,17beta-diol and dihydrotestosterone, respectively. However, results suggest that UGT2B15(Y85) has a higher Vmax than UGT2B15(D85). Specific reverse transcriptase (RT)-PCR analysis revealed expression of the UGT2B15 gene in a wide range of extrahepatic tissues including the human liver, kidney, testis, mammary gland, placenta, adipose, skin, uterus, prostate and lung. The wide expression of UGT2B15 in many tissues indicates that it is a major glucuronidation enzyme in humans.

Alleles↗
PubMed1997

Differential regulation of two uridine diphospho-glucuronosyltransferases, UGT2B15 and UGT2B17, in human prostate LNCaP cells.

Although androgens are important regulators in the prostate, other effectors such as growth factors may also act to maintain normal function of the gland. Human prostate and human prostate cancer LNCaP cells express steroid conjugating uridine diphospho-glucuronosyltransferase (UGT) enzymes, and it was shown that the level of UGT activities and transcripts is down-regulated by androgens, especially dihydrotestosterone (DHT). In the present study, we examined the interaction between androgen, epidermal growth factor (EGF), and steroid UGT enzymes. The formation of DHT glucuronide (DHT-G) was inhibited by 47% when LNCaP cells were treated for 6 days with 10 ng/ml of EGF. Northern blot analysis also demonstrated a decrease in the steady-state level of UGT2B transcripts. Treatment with both DHT (0.5 nM) and EGF (10 ng/ml) caused a greater decrease of DHT glucuronidation and UGT2B messenger RNA levels than when the cells were treated with either compound alone. RNase protection assays showed that treatment with DHT and EGF caused a specific decrease of UGT2B17 transcript in LNCaP cells treated; however, the level of UGT2B15 messenger RNA was not affected. As well, Western blot analysis demonstrated a diminution of UGT2B17 protein level in response to DHT and EGF. These results demonstrate a differential regulation of different isoforms of steroid conjugating UGTs present in human prostate LNCaP cells. UGT2B17 was shown to be more labile than UGT2B15, indicating that regulation of UGT2B17 expression would lead to a more rapid change in the level of glucuronidated steroids.

Cell Division↗
PubMed1996

Isolation and characterization of a novel cDNA encoding a human UDP-glucuronosyltransferase active on C19 steroids.

To isolate cDNA clones encoding novel UGT2B enzymes, human prostate and LNCaP cell cDNA libraries were screened using a pool of steroid-specific UGT2B cDNA probes. In approximately 10(6) recombinants, we isolated 3 cDNA clones of 2.1 kilobases that encode a novel UGT2B enzyme. UGT2B17 is 95% identical with UGT2B15 and 91% identical with UGT2B8. Primary structure analysis of UGT2B17 based on the nucleotide sequence revealed a putative amino-terminal membrane insertion signal peptide, a carboxyl-terminal membrane-spanning region, and three potential asparagine-linked glycosylation sites. UGT2B17 cloned in the pBK-CMV expression vector was transfected into HK293 cells to obtain a stable clonal cell line expressing a high level of the active 53-kDa UGT2B17 enzyme. Of the over 60 endogenous and exogenous substances tested, 25 compounds revealed reactivity. The major substrates are eugenol > 4-methylumbelliferone > dihydrotestosterone > androstane-3alpha, 17beta-diol (3alpha-diol) > testosterone > androsterone (ADT). The apparent Km values obtained with tritiated steroids in intact cells were 0.4 microM for ADT, 0.7 microM for dihydrotestosterone, 1.0 microM for 3alpha-diol, and 3.4 microM for testosterone. Southern blot analysis of reverse transcription-polymerase chain reaction products revealed expression of UGT2B17 mRNA in various tissues including the liver, kidney, testis, uterus, placenta, mammary gland, adrenal gland, skin, and prostate. UGT2B17 is the first human uridine diphosphoglucuronosyltransferase enzyme expressed in extrahepatic tissues to have a specificity for ADT as well as testosterone, dihydrotestosterone, and 3alpha-diol.

Amino Acid Sequence↗
PubMed1996

Characterization of the human and mouse Fli-1 promoter regions.

Overexpression of the Fli-1 gene has been shown to be involved in retrovirus-induced mouse tumors. Cloning of the 5' flanking sequence of the mouse and human Fli-1 exon 1 was performed. At least two major transcription initiation sites were localized respectively at 143 and 114 nucleotides upstream of the previously defined mouse Fli-1 cDNA 5' end. The sequences flanking the CAP sites show good conservation between human and mouse (94%). The promoter region contains a potential TATA box lying 30 bp from one of the major identified CAP sites. Several conserved elements, such as GATA, EBS, GC rich, AP-2, AP-3 elements and a repetition of GA were observed next to the two major CAP sites. Furthermore, this latter was shown to form a H-DNA structure in vitro by S1 nuclease sensitivity experiments. The highly conserved 5' non-translated region of exon 1 is predicted to form a very stable hairpin structure which could regulate the Fli-1 expression at the post-transcriptional level. In Cas-Br-E-induced tumors, all the proviruses are found clustered within 35 nucleotides directly upstream the Fli-1 ATG start codon, thus deleting the hairpin structure from the transcript. Promoter activity was tested using the CAT reporter gene transfected in mouse and human erythroid cell lines. No promoter activity could be detected with various mouse Fli-1 promoter-CAT constructs containing 600 bp of the 5' flanking region, the complete exon 1, the 5' end of intron 1 and/or retroviral LTR sequence. Constructions of the human homologue containing nearly 1.5 kbp of Fli-1 5' flanking region was also inactive in transfected cells. These results suggest that multiple levels of regulation might control the Fli-1 expression.

Animals↗
PubMed1995

Expression of transcripts encoding steroid UDP-glucuronosyltransferases in human prostate hyperplastic tissue and the LNCaP cell line.

The UDP-glucuronosyltransferase (EC 2.4.1.17) enzymes transform many lipophilic compounds to more water-soluble products via conjugation with glucuronic acid. This conversion is responsible for enhancing the excretion of endogenous aglycones such as steroids. To date, several distinct isoforms of steroid UDP-glucuronosyltransferases (UGTs) have been isolated in the human liver. Among these UGTs, UGT2B7 is specific for estriol and 3,4-catechol estrogens, UGT2B15 glucuronidates 17beta-hydroxy-C19 steroids while UGT2B10 has as yet an undescribed activity. To further demonstrate the presence of UGTs in peripheral tissues we studied the expression of these enzymes in human prostate hyperplastic tissue and the LNCaP cell line. Metabolism studies using intact LNCaP cells in culture indicate the presence of UGT activities involved in the glucuronidation of 3alpha-hydroxysteroids (androsterone) and 17beta-hydroxysteroids (testosterone and dihydrotestosterone). Northern blot analysis of poly(A+) RNA from LNCaP cells and prostate using a UGT2B15 cDNA probe revealed two bands of 2.0 and 2.3 kb. In order to identify more specifically the mRNAs detected in Northern blot analysis we used RNase protection and RT-PCR, although, these approaches did not allow detection of UGT2B7 transcripts. Our studies demonstrate the presence of two UGT activities and at least two types of UGT transcripts in both the human prostate and the LNCaP.

Androsterone↗
PubMed1995

Influence of Ammonium Salts and Cane Molasses on Growth of Alcaligenes eutrophus and Production of Polyhydroxybutyrate.

The production of polyhydroxybutyrate (PHB) by Alcaligenes eutrophus DSM 545 was studied in a synthetic medium with 3% glucose at pH 7.0 supplemented with several ammonium substrates and cane molasses. Growth was measured by dry cell weight, and the PHB content was measured by gas chromatography. The effects of ammonium sources such as sulfate, nitrate, phosphate, and chloride salts and those of different ammonium sulfate concentrations were evaluated. The best growth and PHB production were obtained with ammonium sulfate; however, NH(inf4)(sup+) concentrations between 0.5 and 1.5 g/liter showed no significant difference. Ammonium sulfate was therefore used as the sole source of NH(inf4)(sup+) for experiments with cane molasses as the growth activator. Optimal growth and PHB production were obtained with 0.3% molasses. However, the yields of biomass (39 to 48%) and PHB (17 to 26%) varied significantly among the different ammonium substrates and cane molasses concentrations.

Journal Article↗
PubMed1994

Molecular cloning and characterization of the hamster preproenkephalin A cDNA.

The cDNA for hamster preproenkephalin A (ENK) was cloned from an adrenal gland cDNA library constructed in the lambda ZapII vector. A nearly full-length cDNA was obtained and its 5' end region was completed using the technique of rapid amplification of cDNA ends (RACE). The coding and 3' untranslated regions of the hamster ENK cDNA share a high sequence identity with the rat, human, and bovine cDNAs, whereas the sequence identity is lower for the 5' untranslated region. Southern blot analysis of genomic DNA digests showed that a single copy of the ENK gene is present in the hamster haploid genome. Northern blot analysis of poly(A)+RNA from various hamster tissues indicated the following rank order for ENK messenger RNA abundance: adrenal glands > right atrium > brain > left atrium > right ventricle > ventricular septum > left ventricle, whereas primer extension analysis showed a single, identical transcriptional initiation site for the ENK mRNA in all these tissues. The sequence of the 5' untranslated region of the heart ENK cDNA was found to be identical to that from adrenal glands. This rules out the possibility that structural divergences in the 5' untranslated region of the heart ENK mRNA could decrease its translation efficiency and contribute to the very low level of enkephalin-containing peptides in the heart, compared to the adrenal glands.

Adrenal Glands↗
PubMed1994

Comparative effects of quinapril, atenolol, and verapamil on blood pressure and forearm hemodynamics during handgrip exercise.

We compared the effects of angiotensin-converting enzyme inhibition with quinapril to those of selective beta-blockade with atenolol and calcium channel blockade with verapamil in 10 hypertensive subjects in a randomized double-blind placebo-controlled crossover study. All antihypertensive agents reduced baseline mean arterial pressure equally and did not modify forearm vascular resistance compared to placebo. In response to sustained handgrip exercise, both quinapril and verapamil, but not atenolol, attenuated the pressor response. However, verapamil was associated with an exaggerated increase in forearm vascular resistance during handgrip, whereas quinapril did not alter this response compared to placebo. It is concluded that quinapril and verapamil reduce the pressor response during isometric exercise by quantitatively different effects on the vasoconstrictor response in, as well as outside of, skeletal muscles.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Unchanged neurogenic vasoconstrictor response after exercise during angiotensin converting enzyme inhibition with fosinopril.

In a double-blind, randomized, cross-over, placebo- and rest-period controlled study with two 4-week treatment periods, we examined the effects of angiotensin converting enzyme (ACE) inhibition with fosinopril (20 mg/day) on the postexercise pressor and forearm vasoconstrictor responses to a 60 sec cold pressor test. The results indicate that pressor and vasoconstrictor responses were unaffected by prior exercise, fosinopril, and both interventions combined. Expression of the responses as percent change from baseline levels provided identical results indicating that changes in baseline values did not mask an altered vascular responsiveness. It is concluded that skeletal muscle vascular responsiveness to sympathetic nervous activity is unchanged after exercise or during ACE inhibition with fosinopril.

Adult↗
PubMed1994

Survival related to nodal status after sleeve resection for lung cancer.

Sleeve lobectomy is a lung-saving procedure indicated for central tumors for which the alternative is a pneumonectomy. The relation between survival and nodal status is controversial because, in most series, the presence of N1 disease adversely affects the prognosis with few or no long-term survivors. During the period 1972 to 1992, 142 patients underwent sleeve resection for lung cancer at our institution. Mean age (+/- standard deviation) was 60.7 +/- 9.1 years (range 11 to 78 years), and indications for operation were a central tumor in 112 patients (79%), a peripheral tumor in 18 patients (13%), and compromised pulmonary function in 12 patients (8%). Histologic type was predominantly squamous (72.5%) followed by nonsquamous (24.6%) and carcinoid tumors (2.8%). Resection was complete in 124 patients (87%) and incomplete in 18 (13%), and the operative mortality was 2.1% (n = 3). Follow-up was complete for the 139 remaining patients. Including operative deaths, survivals at 5 and 10 years for all patients were 46% (95% confidence intervals 38% to 55%) and 33% (95% confidence intervals 24% to 42%), respectively. For patients with N0 status (n = 73), 5- and 10-year survivals were 57% (95% confidence intervals 45% to 69%) and 46% (95% confidence intervals 32% to 60%); for patients with N1 status (n = 55), these rates were 46% (95% confidence intervals 32% to 60%) and 27% (95% confidence intervals 14% to 40%) (p = 0.13). No patient with N2 status (n = 14) survived 5 years. Local recurrences occurred in 23% of cases, but the prevalence was not statistically different between patients with N0 disease (16.6%) and N1 disease (23.1%) (p = 0.43). These data suggest that sleeve resection is an adequate operation for patients with resectable lung cancer and N0 N1 status. The presence of N2 disease significantly worsens the prognosis and may contraindicate the use of the procedure.

Adolescent↗
PubMed1993

Post-exercise reduction in blood pressure in hypertensive subjects: effects of angiotensin converting enzyme inhibition.

1. Much attention has been given to the effects of various classes of antihypertensive drugs on blood pressure and haemodynamics. The effects of a single bout of exercise on post-exercise blood pressure have also been studied by several investigators. However, the combined effects of prior exercise and antihypertensive medication has drawn less attention. 2. We examined the separate and combined effects of a single bout of exercise and of angiotensin converting enzyme (ACE) inhibition with a new ACE inhibitor (fosinopril, 20 mg day(-1)) on post-exercise blood pressure and systemic and regional haemodynamics. Ten patients with mild-to-moderate hypertension were studied with a double-blind, randomized crossover, placebo- and rest period-controlled study design. 3. At rest, mean arterial pressure (MAP, -10 +/- 2 mm Hg), total peripheral resistance (TPR, -11 +/- 5%) and forearm vascular resistance (FVR, -17 +/- 8%) were significantly (P < 0.05) reduced during ACE inhibition as compared with the placebo phase. 4. During the placebo phase, MAP (-3 +/- 1 mm Hg), TPR (-10 +/- 4%) and FVR (-9 +/- 4%) were lower after exercise as compared with the control rest period. 5. During ACE inhibition, MAP (-3 +/- 1 mm Hg) and TPR (-8 +/- 4%) were lower, but FVR (+32 +/- 15%) was increased after exercise as compared with the control rest period. 6. Thus, blood pressure and TPR decreased similarly after exercise during the placebo phase and during ACE inhibition. However, differences in post-exercise forearm haemodynamics during the placebo phase and during ACE inhibition indicate that underlying regional haemodynamics are modified.

Adult↗
PubMed1992

Critical functional role of the COOH-terminal ends of longitudinal hydrophobic strips in alpha-helices of T4 lysozyme.

The sensitivity of bacteriophage T4 lysozyme function to amino acid substitutions at defined positions in and around the longitudinal, hydrophobic strips of 9 alpha-helices was assessed after systematic replacement of each residue in the protein with a series of 13 amino acids. The hydrophobic strips were defined by identifying the longitudinal sectors in the helices with the highest mean residue hydrophobicities. Sensitivity to mutation (the percentage of replacements leading to loss of function) was calculated for each residue in the following positions: whole protein, helices, hydrophobic strips, other positions within the helices, and various positions within the hydrophobic strips as well as their extensions beyond the helices. Substitutions at positions in the hydrophobic strips led more frequently to loss of function than substitutions in the protein as a whole. One subset, the COOH-terminal hydrophobic strip residues, is apparently critical; substitutions of these residues (but not of their NH2-terminal counterparts) led at least as frequently to loss of function as substitutions of solvent-inaccessible residues, and nearly as frequently as substitutions of the most highly conserved residues.

Algorithms↗
PubMed1989

[Multiple primary lung cancers. The importance of early diagnosis and survival after a new surgical excision].

In a series of 1.025 consecutive resections for bronchogenic carcinoma, 68 patients developed a second primary lung cancer identified as the first site of recurrence (median interval of 38 months). Thirty-nine patients (57%) were asymptomatic (detection by chest-X-Ray (N: 28] or sputum cytology (N: 11) and 22 had one or more symptoms. A reoperation was possible in 50% (N: 34) of all patients with an operative (30 day) mortality of 14.7% (5/34) as compared to 3.5% (26/1.025) for the first procedure. Cumulative survival following the second resection was 33% at 5 years while no inoperable patient survived longer than three years. Clinical presentation of the second carcinoma is a significant prognostic variable since no symptomatic patient survived more than two years while 30% of the asymptomatic group survived 5 years (p less than 0.021).

Actuarial Analysis↗
PubMed1989

Current operative morbidity associated with elective surgical resection for lung cancer.

To determine the current operative morbidity for elective surgery of lung cancer, the authors reviewed the charts of 1076 consecutive patients who underwent pulmonary resection between 1978 and 1984 at two major Canadian teaching hospitals. Of these patients, 731 (68%) had a normal course. Minor complications occurred in 206 patients (19%); the majority were supraventricular arrhythmias (100 events) and atelectasis (41 events). Nonfatal major complications occurred in 105 patients (9.8%). The overall operative death rate was 3.2%. If supraventricular arrhythmias are excluded, nearly 80% of patients had a smooth postoperative course. In order to correlate the occurrence of complications with pre- and perioperative data, several possible risk factors were analysed. For major complications and death, the age, the forced expiratory volume, weight loss, coexisting disease, stage of cancer and extent of resection were significant risk factors (p less than 0.05). The data show that elective pulmonary surgery can be done safely and complications prevented. The necessary requirements are: proper selection of patients, a well-performed operation and prompt treatment of potential problems.

Adult↗
PubMed1989

Carcinoma of the lung. Evaluation of satellite nodules as a factor influencing prognosis after resection.

Satellite nodules are considered to be predictive of poor prognosis in breast cancer and in melanoma. In lung cancer, there is no information as to their definition, prevalence, or implication as a prognosis factor of survival after resection. Over the past 18 years (1969 to 1987), 84 patients underwent pulmonary resection for primary lung cancer accompanied by satellite nodules. These nodules were defined as well-circumscribed accessory carcinoma foci clearly separated from the main tumor but with identical histologic characteristics. All were smaller than the primary carcinoma and most were located within the same lobe. Survival rates of patients with satellite nodules were compared to those of 1021 patients without satellite nodules who underwent resection during the same time interval. The 1-, 3-, and 5-year survival rates for all patients classified as having no satellite nodules were 78%, 54%, and 44%, respectively, and the median survival for the entire group was 30 months. In patients with satellite nodules, these survival rates were 60.9%, 32.7%, and 21.6%, respectively, with a median survival of 15 months. The deleterious effect of satellite nodules was more significant in patients with stage I disease (p = 0.0008) than in patients with stage II (p = 0.0354) or stage III (p = 0.0145) disease. Survival data obtained by comparison of satellite nodule status and histologic characteristics shows that 5-year survival figures are better for patients with no satellite nodules in both the squamous and the nonsquamous groups. This study demonstrates that satellite nodules associated with lung cancer are indicative of locally advanced and/or premetastatic disease. These patients should be included in the stage group IIIa of the TNM stage grouping classification.

Adult↗
PubMed1988

Chronic intermittent elemental diet improves growth failure in children with Crohn's disease.

Growth failure often complicates Crohn's disease in pediatric patients and is principally due to inadequate caloric intake. To assess whether intermittent courses of an elemental diet could reestablish growth, 8 children (aged 9.8-14.2 yr) with Crohn's disease and growth failure entered into a prospective trial. Each patient was studied during an observation year on standard therapy, then for an experimental year during which they received enteral elemental diet 1 out of 4 mo. An age- and disease-matched control group of 4 patients was treated by conventional medical therapy during both years. Elemental diet therapy was administered nocturnally, at home, by continuous nasogastric infusion and increased the daily caloric intake by 25% (p less than 0.01). Anthropometric measurements demonstrated significant height and weight gains in the elemental diet group vs. controls (p less than 0.01). Crohn's disease activity index and prednisone intake decreased significantly in patients receiving elemental diet therapy when compared with themselves and with controls on conventional medical therapy (p less than 0.05). In contrast, the rate of pubertal development was similar in both groups irrespective of the treatment modality. This study demonstrates that chronic intermittent elemental diet effectively reverses growth arrest, while decreasing prednisone requirements and Crohn's disease activity index in pediatric Crohn's disease patients prior to puberty.

Adolescent↗
PubMed1987

Clinical importance of D-1 and D-2 receptors.

The existence of subtypes of dopamine receptors as defined by Kebabian and Calne is now well accepted. The D1 receptor is typically associated with stimulation of adenylate cyclase, while the D2 receptor is either independent of adenylate cyclase or mediates its inhibition. Considerable interest has been generated by the potential physiological and clinical roles of these receptor subtypes. Availability of agonists and antagonists specifically acting at the D1 or D2 receptor site has stimulated research to characterize the functional effects of each receptor subtype. This might facilitate the development of effective compounds to control the signs and symptoms of Parkinson's disease and perhaps prevent the induction of debilitating side effects. Recent evidence indicates that D1 receptor stimulation is required to obtain full expression of the D2 receptor site, which has typically been associated with the clinical benefits of dopaminergic therapy. Both pre- and postsynaptic location of the receptors must also be taken into consideration as well as involvement of other neuronal systems. It appears that in PD, progressive involvement of the dopaminergic pathways is the principal pathological course, however, noradrenergic and serotonergic pathways are likewise involved. This multineuronal involvement suggests that drugs acting specifically at receptor sites, located on both pre- and postsynaptic neurons, might be required at different times during the course of the disease process to control its symptoms and/or the complications occurring after long-term treatment with a given drug.

Animals↗