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Biomedical subjects

P Rat

Publications and source records attributed to P Rat.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Quaternary ammonium cytotoxicity in a human conjunctival cell line].

PURPOSE: Ophthalmic preparations can induce conjunctival toxicity, often caused by preservatives. The aim of this study was to evaluate in vitro cytotoxicity of quaternary ammonium. METHODS: Cytotoxicity tests were done on a continuous human conjunctival cell line using microplate cold light cytofluorimetry. Membrane integrity (neutral red test), DNA condensation (Hoechst 33342 test) and reactive oxygen species (ROS) production (dichlorofluorescein diacetate and hydroethidine tests) were evaluated on living cells treated with different concentrations of benzalkonium chloride, benzododecinium bromide and cetrimide (0.00001 to 0.01%) after 15 minutes of treatment or 15 minutes and 24 hours of cell recovery. RESULTS: All the compounds tested showed similar in vitro effects. Using the neutral red test, we observed a decrease in membrane integrity even at 0.005% and 0.01% (p < 0.001) and after a short time (15 minutes). A stimulation of ROS production (H2O2 and O2) was observed at 0.00001% and above (p < 0.001), associated with a chromatine condensation due to an apoptotic phenomenon. CONCLUSION: A necrotic phenomenon is suggested at high concentrations of quaternary ammonium preservatives whereas an apoptotic mechanism exists for lower concentrations. This toxicity observed in vitro can explain some of the ocular surface damage caused by long-term use of preserved eye-drops.

Anti-Infective Agents, Local↗
PubMed1998

Polymorphic insertions/deletions of both 1550nt and 100nt in two microsatellite-containing, LINE-related intronic regions of the rabbit kappa-casein gene.

The most frequent allele of the rabbit kappa-casein (kappa-Cas)-encoding gene (A allele) has previously been shown to possess two sequences similar to those found in the 5' end of long interspersed repeated elements (LINE). Part of an inverted rabbit LINE is present in the first intron and part of a direct rabbit LINE in the fourth intron. We describe herewith a less frequent allele (B allele) that lacks both 100bp in the first intron and 1550bp in the fourth intron. It was not possible to identify any allele exhibiting only one of the deletions in a population of 55 rabbits. The 100bp present in the first intron of the A allele, but absent from the B allele, are located at the 5' end of the inverse complementary LINE and include the poly (T) track of the LINE. The 1550bp present in the fourth intron of the A allele, but absent from the B allele, include the entire direct LINE sequence. Therefore, the B allele only possesses one partial LINE sequence that is located in the first intron and is truncated when compared to the copy found in the first intron of the A allele. The B allele might thus be more recent than the A allele. Differences between the sequences of transcripts corresponding to each allele are limited to two silent mutations and three modifications in the 3' UTR. In the mammary glands of lactating rabbits, which are homozygous for both alleles, kappa-Cas mRNA accumulate to similar levels and are translated into identical kappa-Cas that are secreted at similar concentrations into milk.

Alleles↗
PubMed1998

In vitro study of cytotoxicity of quinolones on rabbit tenocytes.

Tendinitis and tendon rupture complicating fluoroquinolone therapy have been reported recently, especially affecting men over 60 years. These new quinolones are more potent antimicrobial agents than older nonfluorinated compounds like nalidixic acid. We compared the effects of one quinolone (nalidixic acid) and two fluoroquinolones (norfloxacin and pefloxacin) on cultured rabbit Achilles tendon cells. First, we examined their effects on cell viability, mitochondrial succinate dehydrogenase and global activity, mitochondrial activity using microtitration methods. Pefloxacin and norfloxacin were more cytotoxic than nalidixic acid according to IC50 values. These results confirm that mitochondria represent a biological target of fluoroquinolones. Moreover, the extracellular matrix was studied by molecular hybridization. After a 72 h treatment, the level of type I collagen transcripts was not modified with any of the three antimicrobial agents, whereas mRNA encoding decorin was decreased with 10(-4) mol/L pefloxacin only. The decrease of transcripts encoding decorin suggests that this matrix component is another target of pefloxacin and modification of decorin seems to be an early event (before mitochondrion alteration) which may contribute to the explanation of tendon rupture.

Animals↗
PubMed1998

[Isolated leiomyomatosis of the right renal vein associated with hepatic myelolipoma: diagnostic and therapeutic problems].

The authors report a case of isolated intravenous leiomyomatosis involving a vein of the right renal hilum associated with operated hepatic myelolipoma with a diagnosis of metastatic renal cancer. These tumours are very rare and are usually diagnosed on histological examination of the resection specimen. Although they have a benign histology, they have a very different prognosis and therapeutic management. Although the association of these two exceptional tumours may appear to be purely incidental, a common aetiological factor may nevertheless exist.

Angiography↗
PubMed1997

Time trends in diagnostic strategy, treatment, and prognosis of gastric cancer in the elderly: a population based study.

The impact of changes in diagnostic strategies for gastric cancer and attitudes towards surgery in elderly patients is not known. A population-based series of 842 gastric cancers diagnosed between 1976 and 1993 in patients aged 70 and older in Côte-dOr, France, was used to establish trends in diagnostic strategy, treatment, and prognosis. The use of endoscopy alone increased from 3% (1976-78) to 81% (1991-93). This trend was initially associated with a decrease in the use of x-ray alone, then with a decrease in the use of both x-ray and endoscopy. The proportion of resection for cure increased from 26% during 1976-78 to 43% during 1991-93 (P < 0.001). The proportion of cancers not extending beyond the gastric wall increased from 12% to 24% (P < 0.05). Operative mortality decreased from 38.7% (1976-78) to 13.3% (1991-93) and the corresponding 3-year crude survival rate rose from 7% to 18%. Improvements in the care of gastric cancer in elderly patients have been achieved, but further progress is warranted.

Age Distribution↗
PubMed1996

[Mucinous pancreatic ductal ectasia: mucus secreting tumor of malignant potential].

We report two cases of mucinous pancreatic ductal ectasia including one which progressed to micro-invasive carcinoma. The frequency of this tumor may be under-estimated (24 cases reported in the literature) because of confusion with pseudocysts or mucinous cystadenoma. The diagnosis is made at retrograde cholangiopancreatography. Endosonography is useful for tumors in the head of the pancreas, the predominant localization. At present, there is no test which can distinguish malignant forms from benign mucinous ductal ectasia. Resection of the tumor and the surrounding pancreatitis is the only curative treatment known. Pancreatoduodenectomy may be discussed in elderly patients with a tumor without signs of malignancy.

Adenocarcinoma, Mucinous↗
PubMed1996

[Pulmonary excisions in patients aged 75 and over. Study of postoperative mortality].

The aim of this study was to determine what factors beyond age affect post-operative mortality. We included 971 patients (mean age 61 +/- 10 years; 882 men, 89 women). There were 61 patients (6%) 75 years of age and over. Post-operative death rate was 15% in patients 75 and over versus 6% in patients under 75 (p = 0.01). Other variables significantly correlated with post-operative death after univariate analysis were: heart failure, Karnofsky score, VEMS, CV, PaCO2, tumor size, right side resection, pneumonectomy and large exeresis. Multivariate analysis retained 6 independent variables affecting post-operative mortality: age > or = 75 years (p = 0.019), Karnofsky score (p = 0.0001), right side resection (p = 0.0002, pneumonectomy (p = 0.04, large resection (p = 0.029) and hypocapnia (p = 0.01). If these parameters are considered when deciding on surgery, pulmonary exeresis may be proposed in elderly patients.

Aged↗
PubMed1995

A non-isotopic, highly sensitive, fluorimetric, cell-cell adhesion microplate assay using calcein AM-labeled lymphocytes.

A simple and sensitive cell-cell adhesion microplate assay was established using the cytoplasmic fluorescent dye, calcein AM. The procedure involves three steps: the labeling of lymphocytes with an adequate concentration of calcein AM (20 microM) during a short incubation period (30 min); the adhesion of 2 x 10(5) labeled lymphocytes per well to confluent keratinocyte or fibroblast monolayers grown in microtiter plates for 90 min; and, finally, measurement of the fluorescent signal utilizing a new system of cold-light microfluorimetry (Rat, 1993). During the adhesion assay, the release of calcein from labeled lymphocytes is low and the method permits the detection of as few as 1000 adherent cells. This non-radioactive procedure takes less than 4 h to perform and has proven to be as accurate and reliable as the common method using radioactive isotopes. In addition to its simplicity, the use of a fluorescent molecular probe in conjunction with cold-light microfluorimetry (CLF) offers many advantages of safety and economy, and can readily be adapted to the different cell types that participate in cell-cell adhesion.

Cell Adhesion↗
PubMed1995

Heterogenous effects of natural flavonoids on monooxygenase activities in human and rat liver microsomes.

The in vitro effects of nine flavonoids on different monooxygenase activities from human and rat liver were investigated. Flavonoids belonging to different chemical classes [flavones (chrysin, tangeretin, flavone, 5,6-benzoflavone, 7,8-benzoflavone), flavonols (quercetin), and flavanones (pinocembrin, eriodictyol, flavanone)] were chosen. Ethoxyresorufin O-deethylase (EROD) and benzyloxyresorufin O-debenzylase (BROD) were selected as marker activities of P450 isoenzymes involved in carcinogen activation. Human EROD activity was inhibited by all flavonoids. Flavonoids without hydroxyl groups were more effective than those with hydroxyl groups. Flavonoids with an unsaturated flavone nucleus were more inhibitory than the corresponding saturated analogues. Similar structure-activity relationships were found in microsomes from methylcholanthrene-treated rats. The effects of flavonoids on human BROD activity were quite different from those observed on EROD activity. Nonhydroxylated flavones were effective activators. Hydroxylated flavonoids showed a biphasic effect, being activators at low concentrations and inhibitors at higher concentrations. The effects of flavonoids on BROD activity were rather similar in man and control rats.

Adult↗
PubMed1994

New in vitro fluorimetric microtitration assays for toxicological screening of drugs.

Flow cytometry has been widely used to quantify fluorescent probes in cell culture. However, FCM is not adapted to toxicological screenings due to the cost, the length and the poor reproducibility of this technique. Moreover, several multicenter studies have preferred microtitration methodologies for drug screening. A new fluorimetric technology has been designed that is sensitive and adapted to direct screening in 96-well microplates. This fluorimeter uses cold light technology (CLF) with chemical and physical modifications of the lighting system (Rat et al., 1995). CLF allows reading of UV, visible and near infrared fluorescence by increasing light energy (from 1000 to 2300 lumens) and reducing the calorific part of light (IR > 900 nm, Joule effect). It induces a decrease in background and a 500- to 1000-fold improvement of detection limit of probes in comparison with classical fluorimeters and permits detection of pg/ml to fg/ml. CLF allows easy evaluation of cell injury induced by physical agents (UVA) or chemical toxins (CCl4). Four biological endpoints for cytotoxicity evaluation have been tested with several probes: proliferation (H33258); viability (fluorescent Neutral Red); cell-cell adhesion (calcein-AM); and mitochondrial metabolic effects (Rhodamine 123). Rh123 assay appeared more sensitive than fluorimetric or photometric detection of Neutral Red assay. Cold light fluorimetry (CLF) permits direct detection of low concentrations of probes (pg/ml to fg/ml). CLF is shown to improve classical cytotoxicity assays and, owing to its adaptability to microtitration (in 6-, 12- or 96-well plates and in Petri dishes), it is thus a promising alternative to flow cytometry for drug cytotoxicity screening.

Carbon Tetrachloride↗
PubMed1994

[Papillary and cystic tumor of the pancreas. Histological, immunohistochemical and flow cytometric study].

The authors are reporting a case of papillary and cystic neoplasm of the pancreas. This rare malignant epithelial neoplasm occurs mostly in young women and has a more favorable prognosis than the adenocarcinoma. Radiologic investigations showed a well demarcated, heterogeneous, hypovascular mass. The histological study showed the proliferation of epithelial cells in a papillary pattern. The immunochemistry was negative for markers of adenocarcinoma but positive for vimentin, alpha-1-antitrypsin, alpha-1-antichymotrypsin and neuron specific enolase. Receptors of progesterone were also detected. By flow cytometric analysis, the tumours was hypoploid. The histogenesis of these tumours remained controversed. Ultrastructural details of the neoplastic cells suggest that these tumours originate from small duct cells; detection in several cases of markers for endocrine neoplasm suggests that they originate from primitive multipotential cells, that may show exocrine or endocrine differentiation.

Adult↗
PubMed1994

[Reoperation by thoracic approach after surgery for gastroesophageal reflux].

Eleven patients underwent left transthoracic reoperation for recurrence of hiatus hernia after previous surgical treatment. A left thoracic approach was chosen because of three cases of major obesity, three patients with multiple previous laparotomies, three recurrences of para-esophageal hernia, three associated dyskinetic disorders of lower esophagus. Ten patients underwent a Belsey Mark IV procedure with three myotomies of lower esophagus and one pyloroplasty. One patient underwent a Collis-Belsey procedure. Operative mortality was zero. Every patient had been followed up with a mean of 31 months. Ten patients have a good result. One patient had a massive recurrence of gastroesophageal reflux after Belsey Mark IV which led to a duodenal diversion 18 months later. Although the abdominal approach allows easier dissection of lower esophagus and complementary procedures to the lower esophagus. Results are as good as those of the abdominal approach.

Adult↗
PubMed1993

[Melanoma and primary hyperparathyroidism].

The authors present 3 cases of melanoma associated with a parathyroid adenoma discovered by routine measurement of blood calcium levels. The melanomas were differently located and had different histological degrees. Hypercalcaemia is an infrequent complication of melanoma. According to data found in the literature, it is most often consecutive to bone metastases. The other causes of hypercalcaemia are metastatic extension of melanoma to the parathyroid glands, secretion of parathormone-related peptide (PTH-RP) and the actions of prostaglandins, vitamin D and the osteoclast-activating factor (OAF). Primary hyperparathyroidism due to adenoma has seldom been described associated with melanoma.

Aged↗