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Biomedical subjects

G Benoît

Publications and source records attributed to G Benoît.

At least 37 records · Page 2Linked to original sources
PubMed2000

Data discretization for novel resource discovery in large medical data sets.

This paper is motivated by the problems of dealing with large data sets in information retrieval. The authors suggest an information retrieval framework based on mathematical principles to organize and permit end-user manipulation of a retrieval set. By adjusting through the interface the weights and types of relationships between query and set members, it is possible to expose unanticipated, novel relationships between the query/document pair. The retrieval set as a whole is parsed into discrete concept-oriented subsets (based on within-set similarity measures) and displayed on screen as interactive "graphic nodes" in an information space, distributed at first based on the vector model (similarity measure of set to query). The result is a visualized map wherein it is possible to identify main concept regions and multiple sub-regions as dimensions of the same data. Users may examine the membership within sub-regions. Based on this framework, a data visualization user interface was designed to encourage users to work with the data on multiple levels to find novel relationships between the query and retrieval set members. Space constraints prohibit addressing all aspects of this project.

Computer Graphics↗
PubMed1999

Expression of the RNA component of human telomerase (hTR) in prostate cancer, prostatic intraepithelial neoplasia, and normal prostate tissue.

Telomerase is a ribonucleoprotein that synthesizes telomeric DNA on chromosomal ends. While telomerase is undetectable in most normal somatic tissues, telomerase activation has been detected by a polymerase chain reaction (PCR)-based assay (TRAP) in many immortal cell lines and various cancers, including prostate cancers. To investigate the role of telomerase in prostate cancer at the cellular level, the expression of one of the ribonucleoprotein complexes, the RNA component of human telomerase (hTR), was studied in normal, preneoplastic, and cancerous prostate tissues using a non-radioactive in situ hybridization procedure. Nine human prostates resected at the time of radical prostatectomy were studied. In each case, archival paraffin-embedded samples from normal tissue, prostatic intraepithelial neoplasia (PIN) lesions, the putative precancerous lesion, and prostate carcinomas were selected for in situ hybridization. hTR mRNA expression was detected in carcinomatous glands of seven out of the nine cancers (75 per cent). Furthermore, in seven out of the eight cases showing PIN lesions, the epithelial cells of PIN foci also expressed hTR mRNA. By contrast, in normal tissue, epithelial cells were negative, whereas hTR mRNA expression was detected in the basal cells. The detection of hTR mRNA in PIN lesions clearly strengthens the link between PIN and carcinomatous glands and suggests that telomerase expression occurs early in prostate carcinogenesis. Furthermore, this study confirms previous experimental data suggesting that the basal cell layer is the stem cell compartment in prostate.

Aged↗
PubMed1999

Caverno-pudendal nervous communicating branches in the penile hilum.

Classically, the peripheral neural pathways for erection are proerectile, issuing from the parasympathetic sacral fibres, and antierectile from the thoracolumbar sympathetic trunk. The cavernous nerves as terminal branches of the pelvic plexus convey the parasympathetic fibres to the penis. The pudendal nerve conveys sensory fibres from the penis and somatic fibres to the bulbos-pongiosus and ischiocavernosus striated mm. In animals, it has been demonstrated that the dorsal nerve of the penis contains sympathetic fibres. These findings suggest that communicating branches exist between the cavernous nerves and the dorsal nerve. Our aim in this study was to demonstrate the presence of such connections in man. We dissected 20 fresh male cadavers. The pelvic plexus and pudendal nerves were dissected to identify their terminal branches and connections. Histologic study was performed. Our results showed evidence of communicating nervous branches between the cavernous nerves and the dorsal nerve of the penis. Several variants existed concerning the number and type of connections. The presence of such communicating branches proves that the supralevator and infralevator neural pathways communicate and suggest the possibility of a kind of plasticity of the nervous supply of penile erection. Further studies are needed to identify the nature of these communicating branches.

Adult↗
PubMed1999

Assessment of the functional role of accessory pudendal arteries in erection by transrectal color Doppler ultrasound.

PURPOSE: Anatomical studies have demonstrated accessory pudendal arteries originating from supralevator vessels in about two-thirds of men. Injury to accessory pudendal arteries derived from inferior vesical and obturator arteries has been reported to be responsible for vasculogenic impotence after nerve sparing radical prostatectomy. We performed transrectal and perineal color Doppler ultrasound in patients before radical pelvic surgery to identify accessory pudendal arteries and assess their functional role during erection. MATERIALS AND METHODS: A total of 12 patients with a mean age of 60 years were examined before radical prostatectomy (10) or cystoprostatectomy (2). Transrectal and perineal color Doppler flow imaging and spectral waveform analysis were performed. Peak systolic velocity, end diastolic velocity, resistive index and arterial diameter were measured before and during pharmacologically induced erection. Transrectal color Doppler ultrasound data were compared with intraoperative findings. RESULTS: Transrectal color Doppler ultrasound visualized accessory pudendal arteries derived from supralevator arteries in 9, and prostatic and seminal vesicle arteries in all patients. Perineal color Doppler ultrasound visualized internal pudendal arteries in all patients. After intracavernosal injection of papaverine accessory and internal pudendal arteries displayed similar significant hemodynamic changes. Diameter as well as peak systolic and end diastolic velocities increased, and resistive index decreased. Prostatic and seminal vesicle arteries showed no significant change. Presence and location of accessory pudendal arteries demonstrated by transrectal color Doppler ultrasound were confirmed by intraoperative findings. CONCLUSIONS: During pharmacologically induced erection hemodynamic changes in accessory and internal pudendal arteries are similar to those described in cavernous arteries, thus demonstrating the functional role of accessory pudendal arteries in penile erection. Color Doppler ultrasound appears to be reliable to examine internal and accessory pudendal arteries based on morphological and functional criteria.

Aged↗
PubMed1999

CD44 is an independent prognostic factor in conventional renal cell carcinomas.

PURPOSE: CD44 is a transmembrane glycoprotein involved in cell-cell and cell-matrix interactions. De novo expression of CD44 and its variant isoforms has been associated with aggressive behavior in various tumors. Since few data are available concerning the role of CD44 in the biological behavior of locally confined renal tumors, we analyzed the expression of CD44 in a large set of conventional renal cell carcinomas to determine its prognostic value in association with other clinicopathologic variables. MATERIALS AND METHODS: Ninety-one patients with locally confined conventional renal cell carcinomas were studied. CD44 standard form (CD44H) and v6 isoform expressions were semiquantitatively evaluated on paraffin-embedded tumor tissue by immunohistochemistry. The prognostic value of the usual clinicopathological variables and CD44 expression was tested using Kaplan-Meier plots by the log rank test and Cox multiple hazard regression analysis. RESULTS: No immunostaining was observed in normal renal tissue. Thirty-two of the 66 conventional renal cell carcinomas (48%) showed CD44H membranous staining of the tumor cells. Only 2 cancers displayed CD44v6 immunostaining. Among the different clinicopathological variables analyzed, tumor stage (p = 0.001), nuclear grade (p = 0.01), size (p = 0.02), vascular (p = 0.05) and perirenal adipose tissue invasion (p = 0.005), and CD44H expression (p = 0.01) were found to be significant prognostic parameters for survival using univariate analysis. Moreover, multivariate analysis indicated stage, nuclear grade and CD44 expression as independent prognostic factors both for overall and disease-free survival. CONCLUSION: CD44 can be considered as a useful prognostic parameter in conventional renal cell carcinoma and may be used in evaluation of the outcome of these tumors.

Adult↗
PubMed1998

[Is today's man really less fertile?].

In 1992, a statistical analysis of data from 61 studies of semen quality among normal men led to the conclusion that human sperm count fell of 40% from 1940 to 1990. This meta-analysis has since been invalidated for methodological reasons as well as for statistical reasons, but it caused enormous concern to both the scientific community and to the international media. A decline of human fertility was speculated. To date, the most popular hypothesis offered to explain this alleged decline has been increasing exposure to environmental estrogen mimicking chemicals. However, there is no evidence that male or mammal fertility is declining. Moreover, the sperm count of breeding mammals did not declined in the meanwhile. Since 1992, numerous papers reported on men investigated during the last 20 years have shown conflicting results, from sperm count improvement to sperm count decline. However, several publications included methodological and analytical biases. In fact, the techniques used for semen analysis have to be questioned. It is a subjective exam, lacking laboratory standards and quality control procedures. This induces very important variations between laboratories and between biologists. For the sperm count itself, numerous errors can occur, provoked by the technique, the equipment and the reader: for the same sperm, the coefficient of variation can exceed 40% between two technicians. Therefore, the current techniques of semen analysis cannot warrant epidemiological studies. It is indispensable to admit the limits of the semen analysis in order to improve as much as possible its quality and its reliability.

Adult↗
PubMed1998

Clonal analysis of renal sporadic angiomyolipomas.

Renal angiomyolipomas are benign tumors composed of variable amounts of mature fat, smooth muscle, and thick-walled blood vessels. They occur either sporadically or in association with tuberous sclerosis. Such tumors are considered as hamartomas, but few data are available concerning their pathogenesis. Indeed, it is not known whether angiomyolipoma is a congenital malformation or a neoplastic process. To answer this question, we assessed the clonality of sporadic angiomyolipomas using molecular analysis. Seven women (mean age, 59 years) with renal angiomyolipomas were included. DNA of the tumor and the normal adjacent kidney was extracted from archival paraffin-embedded tissue. DNA methylation pattern at a polymorphic site on the HUMARA gene was studied by polymerase chain reaction (PCR) amplification after methylation-sensitive enzyme digestion. This procedure enables the differentiation between polyclonal and monoclonal lesions according to their X-chromosome inactivation pattern. Five of the seven women included were informative for the HUMARA gene. The mean size of the angiomyolipomas was 53 mm (range, 18 to 110). In one case, a tumor thrombus was observed in the inferior vena cava. Clonal analysis showed that all of the angiomyolipomas and the tumor thrombus studied were monoclonal. This study shows that sporadic angiomyolipomas are monoclonal lesions consistent with neoplastic disorders. This result strongly supports the hypothesis that angiomyolipomas arise from the clonal proliferation of an uncommited cell, which will further evolve toward different cell types.

Adult↗
PubMed1998

De novo expression of CD44 in prostate carcinoma is correlated with systemic dissemination of prostate cancer.

AIMS: To evaluate the role of CD44 in early steps in the development of prostate cancer, and to assess the biological significance of preneoplastic lesions in prostate cancer. METHODS: 38 patients with clinically localised prostate cancer were studied. The standard form of CD44 (CD44H) and v6 isoform expressions were semiquantitatively evaluated on paraffin embedded tumour tissue by immunohistochemistry. Disseminated prostatic cells were detected by prostate specific membrane antigen reverse transcriptase polymerase chain reaction in the blood of each patient before radical prostatectomy. RESULTS: In normal or benign prostate glands, only basal cells showed CD44H and v6 labelling. Fourteen of the 38 prostate cancers (37%) had CD44H membranous staining of prostatic tumour cells. In 18 patients (47%), circulating prostatic cells were detected in blood before surgery. Although no correlation between the expression of CD44 and the Gleason score or staging was observed, a significant correlation was found between the expression of CD44H by tumour cells and prostatic cell blood dissemination (p = 0.04). In 28 cases, foci of prostatic intraepithelial neoplasia were observed, and nine had CD44H immunostaining. CONCLUSIONS: De novo expression of CD44 by prostatic tumour cells is associated with systemic dissemination of prostate cells independently of pathological criteria.

Adult↗
PubMed1997

[Risk of complications during endovesical treatment with BCG for superficial tumor of the bladder].

OBJECTIVES: BCG therapy is the reference adjuvant treatment for multiple and voluminous or recurrent superficial bladder cancer and can cause specific complications. We assessed the frequency and therapeutic modalities involved associated with such complications in a personal retrospective series of patients. PATIENTS AND METHODS: BCG therapy was given to 148 patients who were followed for a mean 40 months. RESULTS: Forty-six percent of the patients developed a follicular reaction in the bladder wall: 14 developed complications requiring anti-tuberculosis treatment. The frequency of BCG therapy complications was higher in patients who had had tuberculosis previously (50%) than those who did not (13.8%). Complications were more frequent after early treatment. In the patients who developed BCGitis with fever, a 3-month regimen of rifampicin and isoniazine appeared to be sufficient. DISCUSSION: The frequency of BCG therapy complications (bladder anomalies excluded) was 7.8% with only 2.8% major complications. The development of a follicular reaction of the bladder wall does not appear to have any prognostic value. Special surveillance is needed in patients with a past history of tuberculosis. CONCLUSION: Adjuvant BCG therapy requires careful follow-up because of the risk of BCGitis which can be effectively treated with a 3-month double-antibiotic regimen.

Adjuvants, Immunologic↗
PubMed1997

Penile arteries in humans. Origin--distribution--variations.

The arterial supply to the penis remains unclear. The frequency of occurrence and functional significance of accessory pudendal arteries remains controversial and it has been suggested that the presence of variations is correlated with atheromatous disease involving internal pudendal arteries. We dissected pelvic and penile arteries in 20 adult fresh male cadavers. The results are expressed according to age and the presence of atherosclerosis. Three patterns of penile arterial supply can be described: type I arising exclusively from internal pudendal arteries (3/20), type II arising from both accessory and internal pudendal arteries (14/20) and type III arising exclusively from accessory pudendal arteries (3/20). This study emphasizes the findings previously reported by early anatomists. No correlation between the presence of accessory pudendal arteries and the extent of atheroclerosis was observed. Accordingly we postulate that these variations are usually congenital. Terminal branches of accessory pudendal arteries mainly supply the corpora cavernosa. As they are located very close to the prostate, the risk of injury is high during radical prostatectomy. The possibility of impotence from such injury after radical prostatectomy needs therefore to be reconsidered.

Aged↗
PubMed1995

[Neoplastic ureteral obstruction: drainage by percutaneous nephrostomy or double J catheterization].

OBJECTIVES: Neoplasic obstruction of the ureter is observed in patients with pelvic or extra-pelvic cancer. Indications of upper urinary tract drainage need to be clarified. METHODS: Percutaneous nephrostomy or double J catheter drainage was performed in 104 patients with ureteral obstruction due to pelvic cancer (bladder, prostate, uterus, ovary, rectum) or extra-pelvic cancer (usually breast and digestive cancers). Percutaneous nephrostomy or double J catheter was the first drainage procedure in 85 and 76 patients respectively. RESULTS: Success rate in first intention drainage was 74.5% with the double J catheter. When this procedure was impossible, percutaneous nephrostomy was always performed. In 52 cases we attempted to convert the nephrostomy to double J catheter drainage. Success rate was 68.8%. The main complications observed were ineffective drainage (12.5%) and infection (10.5%). CONCLUSION: These patients have a mean survival of 6.8 months despite the chemotherapy which is facilitated by the improved renal function.

Adult↗
PubMed1994

[Erection disorders: efficacy and tolerability after 6 months of intracavernous self-injections of alprostadil. Groupe Français d'Etude de l'Alprostadil].

OBJECTIVES: Self-administered intracavernous injections, notably with alprostadil are currently the most widely used non-psychotherapeutical treatment of erectile dysfunction. We assessed the effectiveness of this treatment after 6 months of self-injections. METHODS: Efficacy, acceptability and tolerance to alprostadil self-administered via intracavernous injections for 6 months was evaluated in 144 men, age 24 to 72 years, and followed monthly after an initial training period and search for the optimal dose. RESULTS: The mean number of self-injections was 5.5 at a mean dose of 18.6 micrograms per injection. From the first to sixth month, the frequency of complete erections after self-injection rose from 62% to 77% and failures declined from 8% to 3%. After six months, 40% of the patients had abandoned the treatment including 9% who abandoned during the first month, usually due to poor acceptance and because of cure in two patients (4.5%). Patients reported sexual intercourse after self-injections as satisfactory in 81% of the cases; 66% of their partners reported satisfactory intercourse. Tolerance assessment revealed pain in 14% of the patients and decreasing effect with time in two patients who discontinued self-injections for this reason. Other undesirable side effects were infrequent, usually related to technical injection errors and decreasing effect with time. One case of priapism and two indurations of the cavernous bodies were also observed. CONCLUSION: Self-administration of intracavernous alprostadil can lead to rigid erection in patients with erectile dysfunction. Patients are generally well satisfied and tolerance is good.

Adult↗
PubMed1994

[Diagnosis and treatment of impotence. Indications of intracavernous injections].

Based on progress in our understanding of the physiology of erection, intracavernous injections of vasoactive substances have completely changed the treatment of impotence. Essentially, erection results from the effect of smooth muscle relaxation in the vascular walls leading to local fall in vascular resistance and increased arterial flow combined with smooth muscle relaxation within the sinusoid spaces of the cavernous bodies. Smooth muscle cell tone is regulated not only by the classical norepinephrine and acetylcholine neurotransmitters, but also by other non-adrenergic and non-cholinergic neurotransmitters released locally. Although the "erectile neurotransmitter" has not been identified parasympathetic nerve terminaisons release nitric oxide (NO) a powerful myorelaxant agent. NO is also synthetized by the endothelial cells on the internal surface of the sinusoidal spaces. These recent findings have led to the use of papaverin to reduce the level of intracellular calcium, alpha-blockers to antagonize alpha-receptor and prostaglandin to inhibit norepinephrine release. Vasoactive intestinal polypeptide, a myorelaxing agent, and linsidomine which favours NO release have also been used. Diagnostic tests by intracavernous injections are indicated as part of the complete work-up in patients consulting for impotence. Therapeutic indications for auto-injections require careful choice of the agent and the dosage to inject depending on the cause of the impotence and the patient's demands and capacity to learn the technique. Papaverin or prostaglandin E1 alone or in combination with phentolamine give good results. Rigid erections can be obtained in over 60% of the patients. Alpha-blockers appear to be the least active in terms of rigidity. Mid-term results of intracavernous fibroses have been reported after papaverine injections. Priapism is the main secondary effect of intracavernous injections.

Humans↗