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Biomedical subjects

J Tessier

Publications and source records attributed to J Tessier.

At least 19 recordsLinked to original sources
PubMed2006

NPT2a gene variation in calcium nephrolithiasis with renal phosphate leak.

A decrease in renal phosphate reabsorption with mild hypophosphatemia (phosphate leak) is found in some hypercalciuric stone-formers. The NPT2a gene encodes a sodium-phosphate cotransporter, located in the proximal tubule, responsible for reclaiming most of the filtered phosphate load in a rate-limiting manner. To determine whether genetic variation of the NPT2a gene is associated with phosphate leak and hypercalciuria in a cohort of 98 pedigrees with multiple hypercalciuric stone-formers, we sequenced the entire cDNA coding region of 28 probands, whose tubular reabsorption of phosphate normalized for the glomerular filtration rate (TmP/GFR) was 0.7 mmol/l or lower. We performed genotype/phenotype correlations for each genetic variant in the entire cohort and expressed NPT2a variant RNAs in Xenopus laevis oocytes to test for cotransporter functionality. We identified several variants in the coding region including an in-frame 21 bp deletion truncating the N-terminal cytoplasmic tail of the protein (91del7), as well as other single-nucleotide polymorphisms that were non-synonymous (A133V and H568Y) or synonymous. Levels of TmP/GFR and urine calcium excretion were similar in heterozygote carriers of NPT2a variants compared to the wild-type (wt) homozygotes. The transport activity of the H568Y mutants was identical to the wt, whereas the N-terminal-truncated version and the 91del7 and A133V mutants presented minor kinetic changes and a reduction in the expression level. Although genetic variants of NPT2a are not rare, they do not seem to be associated with clinically significant renal phosphate or calcium handling anomalies in a large cohort of hypercalciuric stone-forming pedigrees.

Adult↗
PubMed2002

Lactation response and nitrogen, calcium, and phosphorus utilization of dairy goats differing by the genotype for alpha S1-casein in milk, and fed diets varying in crude protein concentration.

Twenty-four dairy goats were used in a preliminary trial to evaluate the effect of the genotype for alpha S1-casein (alpha S1-CN) in milk [homozygous variant A/A (n = 12) or F/F (n = 12)] on milk yield and composition for 2 wk from kidding. After this period, the main trial aimed at determining the effects of the genotype for alpha S1-CN in milk, the dietary crude protein concentration on milk yield and composition, and utilization of N, Ca and P. The goats within each genotype were allocated to a 3 x 3 Latin square for 14 wk with three crude protein concentrations in the total mixed ration (13.2, 16.8, and 19.8% of dry matter) and three periods (wk 3 to 6, wk 8 to 11, and wk 13 to 16 postpartum) as factors. Balances of N, Ca, and P were determined in the last week of each period. Two wk after kidding, the alpha S1-CN A/A goats had higher percentage and yield of protein and lower body weight than the alpha S1-CN F/F goats. During the main trial, yields of protein and fat, as well as percentages of fat and protein in milk were higher for the alpha S1-CN A/A goats than for the alpha S1-CN F/F goats, independent of dietary CP concentration and period. Efficiency of N digestion for milk N was higher for the alpha S1-CN A/A goats than for the alpha S1-CN F/F goats. Urinary N as a percentage of digested N, and total N excretion expressed relative to milk N were lower for the alpha S1-CN A/A goats than for the alpha S1-CN F/F goats. Neither the apparent absorption of calcium or phosphorus was affected by the genotype for alpha S1-CN. Goats fed the low crude protein diet had lower milk yield and lower yields of fat and protein than those fed the other diets. Increasing dietary crude protein concentration increased urinary N, milk N, and N excretion relative to milk N; it also decreased the efficiency of digested N for milk N. In conclusion, selection of goats with a genetically higher yield of casein and fed with diets formulated to reduce N excretion improves the cheese-making properties of goat milk and reduces concerns about N wastes in the environment.

Animals↗
PubMed2001

A family-based study of metabolic phenotypes in calcium urolithiasis.

BACKGROUND: A family history increases the risk of kidney stone passage independent of dietary risk factors. However, the metabolic basis for familial aggregation of urolithiasis is unknown. METHODS: We evaluated metabolic risk factors in families with at least two sibs with a history of calcium stones. Sibs underwent outpatient evaluations simultaneously, including 24-hour urine collection and oral calcium loading. Phenotypes were compared between affected and unaffected sibs from the same sibship. RESULTS: Eighty-three sibships comprising 388 sibs (212 affected sibs, 114 males and 98 females, and 176 unaffected sibs, 68 males and 108 females) from 71 families were analyzed. Daily urine calcium excretion was higher in affected compared with unaffected sibs (0.64 +/- 0.33 vs. 0.50 +/- 0.22 mmol Ca(2+)/mmol creatinine, respectively, P < 10(-5)). This corresponded to absolute values of 7.4 +/- 3.9 and 5.1 +/- 2.3 mmol Ca(2+)/day, respectively, for affected and unaffected males, and 5.4 +/- 2.6 and 4.2 +/- 1.9 mmol Ca(2+)/day, respectively, for affected and unaffected female sibs. When analyzed by tertile of onset age of stone passage, the differences in urine calcium were only significant in the first two tertiles (with onset age of stone passage <35 years). The fasting urine Ca(2+)/creatinine ratio was significantly higher in stone formers compared with control sibs (0.46 +/- 0.27 vs. 0.40 +/- 0.27, P = 0.04), as was the postcalcium load Ca(2+)/creatinine ratio (0.57 +/- 0.46 vs. 0.43 +/- 0.41, respectively, P = 0.02). Body mass index was marginally significantly higher in stone forming sibs (P = 0.04). Other urine phenotypes, including oxalate, phosphate, magnesium, citrate, urate, sodium, ammonium, and volume, were not associated with stone passage. CONCLUSION: Increased urine calcium excretion is the only phenotype associated with a kidney stone formation in these French-Canadian families.

Adolescent↗
PubMed2001

Characterization of adenovirus-induced inverted terminal repeat-independent amplification of integrated adeno-associated virus rep-cap sequences.

Stable packaging cell lines expressing the rep and cap genes for recombinant adeno-associated virus type 2 (rAAV-2) assembly constitute an attractive alternative to transient transfection protocols. We recently characterized a stable HeLa rep-cap cell clone (HeRC32) and demonstrated that upon vector transfection and adenovirus infection, efficient rAAV assembly correlated with a 100-fold amplification of the integrated rep-cap sequence with the inverted terminal repeats (ITRs) deleted. We now report a more detailed analysis of this phenomenon and highlight the key cellular and viral factors involved. Determination of the rep-cap copy number of HeRC32 cells indicated that maximum rep-cap amplification occurred between 24 and 48 h following adenovirus infection. Analysis by pulsed-field gel electrophoresis of adenovirus-infected HeRC32 cells indicated that amplified rep-cap sequences were found in an extrachromosomal form. Amplification of the rep-cap sequence with the ITRs deleted was not dependent on adenovirus replication and still occurred when the highly specific adenovirus polymerase was inactivated. In contrast, amplification was inhibited in the presence of aphidicolin, indicating that cellular polymerases were needed. Our study also documented that among the adenovirus gene products, the DNA-binding protein (DBP) was essential, since rep-cap amplification was severely abrogated when HeRC32 cells were infected at a nonpermissive temperature with an adenovirus mutant encoding a thermosensitive DBP. Furthermore, expression of DBP alone in HeRC32 cells was sufficient to induce a sustained level of rep-cap amplification. Finally, immunofluorescence analysis showed that HeRC32 cells expressing the DBP also simultaneously expressed the Rep proteins, suggesting a possible involvement of the latter in rep-cap amplification. Indeed, the lack of detectable amplification in an adenovirus-infected stable rep-cap HeLa cell clone unable to produce Rep proteins further supported that, among the viral gene products, both the DBP and Rep proteins are necessary to induce the targeted amplification of the integrated rep-cap sequences in the absence of the AAV ITRs.

Adenoviridae↗
PubMed2001

Novel cis-acting replication element in the adeno-associated virus type 2 genome is involved in amplification of integrated rep-cap sequences.

This study identifies a region of the adeno-associated virus type 2 (AAV-2) rep gene (nucleotides 190 to 540 of wild-type AAV-2) as a cis-acting Rep-dependent element able to promote the replication of transiently transfected plasmids. This viral element is also shown to be involved in the amplification of integrated sequences in the presence of adenovirus and Rep proteins.

Base Sequence↗
PubMed1999

Burch colposuspension: long-term results and review of published reports.

OBJECTIVES: To review our long-term results with the Burch colpocystourethropexy, compare our results with those in recently published reports, and define factors that may influence the long-term outcome of this procedure. METHODS: A group of 79 patients who underwent Burch colposuspension as modified by Tanagho between January 1985 and January 1991 were studied retrospectively. Preoperative investigation consisted of clinical history, physical examination, cystourethroscopy, multichannel urodynamic evaluation, including pressure-flow studies, and static and dynamic urethral pressure profile analysis. A postal survey was sent to all patients to evaluate their symptoms and the impact on their quality of life. RESULTS: The mean follow-up was 7.6 years (range 5.3 to 10.8). Forty-four percent of patients were considered cured (responders), 25% significantly improved (partial responders), and 31% failures (nonresponders). The success rate was higher among patients who had not undergone previous continence surgery (75%) or hysterectomy (78%) than among those who had previously undergone continence surgery (59%) or hysterectomy (65%). Seventy-five percent of the patients were responders or partial responders if the bladder was stable preoperatively, as opposed to 70% when the bladder was unstable before surgery. Analysis of the postal questionnaire indicated a statistically significant difference in terms of irritative symptoms between the responder and partial responder groups combined and the nonresponder group. CONCLUSIONS: More than two thirds (69.6%) of our patients who underwent a Burch-Tanagho colpocystourethropexy had a favorable long-term outcome (mean 7.6 years). Previously failed continence procedures, unstable bladder preoperatively, and previous or concomitant hysterectomy had a negative influence on the final outcome in the long term from the clinical point of view, even if, statistically, the difference was not significant. The incidence of irritative symptoms and nocturia were significantly higher among nonresponders than among responders and partial responders. More attention paid to these symptoms during the post-operative follow-up should increase the perception of success by the patient after retropubic colpocystourethropexy.

Adult↗
PubMed1999

Meiotic instability of human minisatellite CEB1 in yeast requires DNA double-strand breaks.

Minisatellites are tandemly repeated DNA sequences of 10-100-bp units. Some minisatellite loci are highly unstable in the human germ line, and structural analysis of mutant alleles has suggested that repeat instability results from a recombination-based process. To provide insights into the molecular mechanism of human minisatellite instability, we developed Saccharomyces cerevisiae strains carrying alleles of the most unstable human minisatellite locus, CEB1 (ref. 2). We observed that CEB1 is destabilized in meiosis, resulting in a variety of intra- and inter-allelic gains or losses of repeat units, similar to rearrangements described in humans. Using mutations affecting the initiation of recombination (spo11) or mismatch repair (msh2 pms1 ), we demonstrate that meiotic destabilization depends on the initiation of homologous recombination at nearby DNA double-strand break (DSBs) sites and involves a 'rearranged heteroduplex' intermediate. Most of the human and yeast data can be explained and unified in the context of DSB repair models.

Alleles↗
PubMed1997

Retropubic cystourethropexy: is it an obstructive procedure?

PURPOSE: We sought to establish whether colpocystourethropexy creates bladder outlet obstruction, as evaluated by pressure-flow studies. MATERIALS AND METHODS: We retrospectively analyzed the records of 50 women. Preoperative evaluation included a detailed questionnaire, physical examination, urine culture, cystourethroscopy and multichannel urodynamic testing. Every patient underwent retropubic colpocystourethropexy according to the Tanagho modification of the original Burch technique. An average of 3 months after the operation clinical evaluation and identical multichannel urodynamic testing were repeated. Preoperative and postoperative urodynamic parameters were compared for each patient and statistical differences were established using Student's 2-tailed t test. RESULTS: No statistically significant difference was demonstrated in static urethral pressure profile parameters and in parameters during the filling phase of the cystometrogram except for cystometric capacity, which decreased after surgery (p = 0.02). In contrast, all 5 pressure-flow parameters analyzed (minimum urethral opening pressure, detrusor pressure at maximum flow, maximum flow, theoretical cross-sectional area and theoretical diameter of the flow rate controlling zone) showed statistically significant differences induced by surgery. Pressure-flow data reported on Schäfer's diagram and on the Abrams-Griffiths nomogram failed to demonstrate urodynamically significant obstruction created by surgery. CONCLUSIONS: Our data suggest that colpocystourethropexy does not create obstruction but, rather, restores pressure-flow conditions to a normal or nearly normal level.

Adult↗
PubMed1996

Quantitative method for the evaluation of biomicrocapsule resistance to mechanical stress.

A quantitative method has been developed for the evaluation of biomicrocapsule resistance to mechanical stress. Fluorescein isothiocyanate-labelled dextran (M.W. 2 x 10(6)) was microencapsulated in alginate-poly-L-lysine membranes. Microcapsules of 302.0 +/- 3.2 microns were mixed with 3 mm glass beads and continuously agitated for 0 to 144 h. The percentage of broken capsules was calculated by measuring the fluorescence in the supernatant and in the residual intact capsules after the latter were dissolved. The fluorescence method was validated by comparison with a manual method (handpicking under a stereomicroscope). The highest percentage of broken capsules was obtained with a ratio of 225 +/- 25 glass beads per 1000 microcapsules. The percentage of broken capsules increased linearly from 7.3% at 12 h to 48.3% at 72 h of continuous agitation. The applicability of the method was evaluated by studying microcapsules of potentially different levels of resistance. The results confirmed that capsule resistance is improved by increasing poly-L-lysine concentrations and incubation times. Microcapsules made with guluronic acid-rich alginate were stronger than those made with mannuronic acid-rich alginate. In conclusion, this is a simple, precise and sensitive method for the quantification of biomicrocapsule resistance to mechanical stress.

Alginates↗
PubMed1995

[The importance and significance of post-micturitional bladder residue in the evaluation of prostatism].

The presence of a significant post-voiding residue is often considered to be secondary to bladder neck obstruction and frequently constitutes the main indication for transurethral resection of the prostate. In order to validate this approach, the files of 350 patients presenting with symptoms of prostatism and assessed by urodynamic studies were analysed retrospectively. The results of the study demonstrated that, regardless of the value of the residue, approximately 30% of patients were not obstructed despite a high post-voiding residue (PVR), while approximately 70% of patients with minimal or no PVR were considered to be obstructed on the basis of urodynamic criteria. These results therefore demonstrate that the presence of a post-voiding residue is not indicative of bladder neck, but reflects a lesion of the detrusor. Considered alone, it therefore should not constitute an indication for transurethral resection of the prostate.

Humans↗
PubMed1993

Spinothalamocortical inputs nonpreferentially innervate the superficial and deep cortical layers of SI.

Using a combined anterograde and retrograde tracing technique, we examined the distribution pattern of the thalamocortical cells which projected to superficial layers of the hand region of the primary somatosensory cortex (hSI), and quantitatively analyzed the retrogradely labeled cells which putatively contacted terminals of the spinothalamic tract (STT) in the squirrel monkey and the macaque. Less than 25% of the superficial hSI projecting cells were putatively contacted by terminals of cervical enlargement spinothalamic neurons. These cells were primarily located in ventroposterior lateral, ventroposterior inferior and centrolateral nuclei. Although the number of superficial hSI projecting cells numbered less than 20% of the total hSI projecting cells, their patterns of location and their proportion of overlap with STT terminals within each thalamic nucleus were similar. It is suggested that the spinothalamic nociceptive information input to to the cortex equally accesses both superficial and deep SI.

Animals↗
PubMed1991

Trabecular smooth muscle modulates the capacitor function of the penis. Studies on a rabbit model.

We investigated the role of trabecular smooth muscle tone in regulation of intracavernosal pressure, venous outflow resistance, and penile capacitance. In an isolated rabbit whole penis model, corpora cavernosa were infused with either contracting (high K(+)-norepinephrine combination) or relaxing (no added Ca(2+)-papaverine combination) physiological salt solutions while intracavernosal pressure was recorded. An infusion pump regulated by an intracavernosal pressure feedback mechanism enabled the measurement of flow necessary to maintain intracavernosal pressures at 30, 60, 90, 120, and 150 mmHg under steady-state conditions (inflow = outflow). These experiments allowed resistance to outflow from corpora to be calculated when trabecular smooth muscle was either constricted or relaxed. Decay in intracavernosal pressure over time from various predetermined intracavernosal pressures (150, 120, 90, 60, and 30 mmHg) was studied under conditions of zero inflow following contraction or relaxation of trabecular smooth muscle. This permitted calculation of the time constant, which together with the outflow resistance, permitted the calculation of penile capacitance. When smooth muscle is relaxed, venous outflow resistance is high, constant, and independent of intracavernosal pressure. Furthermore, relaxation of smooth muscle allows expansion of corpora with accumulation of volume under pressure, enabling the penis to act as a capacitor. This capacitor function is limited in the presence of constant high outflow resistance by stiffness of the fibroelastic elements of penis, tunica, and fibroelastic frame, which exhibit nonlinear deflection trends. Analysis of these variables has led us to propose a model for penile erection.

Animals↗
PubMed1990

Does urethral instrumentation affect uroflowmetry measurements?

Uroflowmetry was performed before and after urethral catheterisation in 129 patients. Uroflowmetry measurements were significantly modified by urethral instrumentation. In males, both maximum and mean flow rates decreased following urethral catheterisation, while in females only the maximum flow rate decreased, the mean flow rate remaining unchanged. Voided volume increased (and consequently residual urine decreased) in females after catheterisation, but did not change significantly in males. False positive results were encountered in 32% of patients and false negative results in 11% when flowmetry was done immediately after catheterisation. Uroflowmetry after urethral instrumentation is not recommended.

Adolescent↗