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Biomedical subjects

C Rich

Publications and source records attributed to C Rich.

At least 19 recordsLinked to original sources
PubMed1996

Enteroadherent Escherichia coli and diarrhea in children: a prospective case-control study.

The relative contribution of diarrheagenic Escherichia coli was examined during a 1-year prospective study of hospitalized children in Clermont-Ferrand, France, including 220 case patients (with diarrhea) and 211 matched controls. Fecal isolates were characterized by means of their pattern of adherence to HEp-2 cells and by colony hybridization with DNA probes specific for the six categories of diarrheagenic E. coli. No enteroinvasive or enterotoxigenic E. coli isolates were isolated. Twenty-eight (6.5%) eae-positive isolates and 39 (9%) enteroaggregative E. coli isolates characterized with the aggregative adherence probe and/or by their adherence pattern were detected; they were equally distributed among the patients and the controls. Diffusely adhering E. coli was the predominant pathotype: 30.7% were detected by their adherence pattern and 13.7% were detected with the daaC probe. They were isolated with similar frequencies from the patients and the controls, thereby showing no association with diarrhea. However, daaC-positive strains were significantly associated with a past record of urinary tract infections. These results suggest that the diffusely adhering E. coli organisms isolated in the present study are not true intestinal pathogens but may be regarded as resident colonic strains.

Adolescent↗
PubMed1996

Temporary vessel occlusion for aneurysm surgery: risk factors for stroke in patients protected by induced hypothermia and hypertension and intravenous mannitol administration.

Temporary vessel occlusion is an effective technique used by microvascular surgeons to facilitate dissection and permanent clipping of cerebral aneurysms; however, several questions remain regarding the overall safety of this technique. To identify technical and patient-specific risk factors for perioperative stroke, the authors examined a series of patients in whom induced hypertension and mild hypothermia and intravenous mannitol administration were used as protection during temporary vessel occlusion for aneurysm clipping. The study comprises a nonconcurrent prospective analysis of 132 consecutive aneurysm clippings performed with the aid of temporary vascular occlusion and a specific antiischemic anesthetic protocol at the Massachusetts General Hospital from 1991 to 1993. Factors studied included duration of the temporary clip application, number of occlusive episodes, patient age and neurological status, presence of preoperative subarachnoid hemorrhage (SAH), and intraoperative aneurysm rupture ("forced" temporary clipping), as well as whether proximal vessel occlusion or complete aneurysm trapping was used. In a univariate analysis, patient age, intraoperative aneurysm rupture, temporary clipping lasting more than 20 minutes, clipping between the 4th and 10th day after SAH, and multiple clipping episodes were all significantly associated with stroke outcome. Multivariate logistic regression revealed that intraoperative aneurysm rupture (relative risk 5.6, p = 0.02) and a duration of temporary clip application that lasted more than 20 minutes (relative risk 9.4, p = 0.04) were independently associated with stroke outcome. Overall, 5.2% of the patients had postoperative clinical strokes. Based on their findings the authors conclude that temporary clipping is a safe adjunct to aneurysm surgery, particularly when the duration of clipping is short.

Adult↗
PubMed1996

Experimental evaluation of a hydroxylapatite reservoir tube shunt in rabbits.

BACKGROUND AND OBJECTIVES: Anterior chamber tube shunts of various design are of increasing importance in the surgical management of refractory glaucoma. However, the reservoirs that are commonly used today are made of a silicone or an acrylic material that may become enveloped by a fibrous capsule, which in turn may impede aqueous resorption. In this study, the authors investigated the properties of hydroxylapatite (HA) as a reservoir in gonioimplants, using three different types of HA reservoir designs. It has been demonstrated that HA orbital implants become vascularized, and the authors hypothesized that this feature of HA might modify the development of the fibrous capsule, enhancing the efficacy and decreasing the size of the implants. MATERIALS AND METHODS: HA reservoirs with Silastic tube shunts were implanted in the right eyes of six Dutch-belted rabbits. Clinical examinations were performed and intraocular pressure was measured periodically for 16 weeks postoperatively. Prior to euthanasia, fluorescein-labeled latex microspheres were injected into the anterior chamber to demonstrate implant patency. Light microscopy was used to study the tissue response to the implants and the pathways of aqueous flow. RESULTS: In general, the authors found a granulomatous inflammatory response to the HA accompanied by neovascularization into the implant and minimal fibrous encapsulation of the reservoir. CONCLUSIONS: The use of HA as a suprascleral reservoir has several advantages, the major one being a theoretical increase in the functional lifetime of the implant.

Animals↗
PubMed1995

Retrospective case-control study of diffusely adhering Escherichia coli and clinical features in children with diarrhea.

A retrospective case-control study with a small population group revealed that, among clinical signs, vomiting but not diarrhea was significantly associated with the presence of diffusely adhering Escherichia coli (DAEC) in children suffering from gastroenteritidis (P < 0.05). Of the children carrying DAEC strains, those who were F1845 DNA probe positive had a significantly longer hospital stay than those who were F1845 DNA probe negative. We believe that the heterogeneity of DAEC strains is responsible for the discrepant results concerning their involvement in disease and that only some of these strains are really pathogenic for children.

Adolescent↗
PubMed1994

Survey of clinical isolates of diarrhoeogenic Escherichia coli: diffusely adhering E. coli strains with multiple adhesive factors.

A total of 335 Escherichia coli strains were isolated from sporadic cases of aqueous diarrhoea in patients hospitalized in Clermont-Ferrand, France, during 1991 and 1992. Many of these strains belonged to the diffusely adhering E. coli (DAEC) group, since 51 of them (15.2%) hybridized with the daaC probe corresponding to the accessory gene of the F1845 adhesin and 13 (3.9%) with the AIDA-I (adhesin involved in diffuse adhesion-I) structural gene. The other pathogenic E. coli groups were weakly represented: 0.6% (2 strains) of enterotoxigenic E. coli (ETEC), 0.6% (2 strains) of enterohaemorrhagic E. coli (EHEC) and 3.9% (13 strains) of enteroaggregative E. coli (EAggEC). Neither enteropathogenic E. coli (EPEC) nor enteroinvasive E. coli (EIEC) were isolated in our study period. Among the DAEC strains studied, we described two major surface proteins of 16 and 29 kDa. We showed that the 16-kDa protein (CF16K) was involved in adhesion in vitro to Caco-2 and HEp-2 cells. Pretreatment of bacteria with anti-CF16K serum or of Caco-2 cells with purified CF16K greatly decreased the adhesion of the E. coli CF1085 strain producing the CF16K protein to both cell types. The CF16K adhesive factor was found in 9.5% (33 strains) of the 335 E. coli strains studied by colony immunoblot assays with anti-CF16K serum. Twelve strains producing CF16K hybridized with the daaC probe, indicating that the CF16K is not related to the Dr family adhesins which recognized the Dr blood group antigen as receptor. The 29-kDa protein, isolated from 9 strains out of the 335 studied (5.1%), was identified as the CS31A antigen by Western blot assay using anti-CS31A serum and by hybridization experiments with a CS31A DNA probe. This antigen is routinely observed in septicaemic or enterotoxigenic bovine E. coli strains. We showed that a single diarrhoeogenic E. coli strain could harbour at least two adhesive factors, since 36% of CF16K E. coli strain producers and 68.4% of CS31A E. coli strain producers hybridized with the daaC DNA probe.

Adhesins, Escherichia coli↗
PubMed1994

Self-transmissible R plasmids encoding CS31A among human Escherichia coli strains isolated from diarrheal stools.

The CS31A antigen was first described for septicemic and enterotoxigenic bovine E. coli strains. In our study, of 597 human Escherichia coli strains isolated from diarrheagenic stools of hospitalized patients, 30 (5%) hybridized with the CS31A DNA probe. These CS31A-positive E. coli strains diffusely adhered to Caco-2 and/or HEp-2 cells and produced a major surface protein of either 30 or 30.5 kDa according to the strain. These proteins were antigenically related to the two forms of the CS31A antigen, namely, CS31A-L and CS31A-H. Genes encoding CS31A were located on 140-kb conjugative R plasmids. E. coli transconjugants expressed major surface proteins similar to those of the wild-type strains and adhered to Caco-2 and/or HEp-2 cells. An association of CS31A and another adhesive factor of the Dr family was found in 70% of wild-type strains, since 21 strains hybridized with the diffuse adhesion DNA probe corresponding to the accessory gene (daaC) of the F1845 adhesin. Comparison of the restriction patterns of the 140-kb R plasmids of the CS31A-positive E. coli strains showed these plasmids to be similar. Hybridization experiments indicated that the genes encoding CS31A and resistance to penicillin were located together on either of two 20- or 27-kb EcoRI restriction fragments in four E. coli strains. We reported a similar linkage between these genes in Klebsiella pneumoniae strains which produced CF29K, a CS31A-like antigen. These results suggest a horizontal transfer between E. coli and K. pneumoniae strains.

Adult↗
PubMed1994

Six-month stability of psychiatric diagnoses in first-admission patients with psychosis.

OBJECTIVE: The short-term diagnostic stability of schizophrenic and other psychotic disorders was examined in first-admission patients, with attention to the principal reasons for diagnostic change. METHOD: Hospitalized first-admission patients (N = 278) participating in an epidemiologic study were interviewed at baseline and after 6 months with the Structured Clinical Interview for DSM-III-R. A best estimate diagnosis was made at both time points with the use of all available sources of information. Reasons for changes in diagnosis were determined by two psychiatrists. RESULTS: Affective psychosis and schizophrenic disorders were relatively stable broad diagnostic categories over the 6-month period, with 86.5%-88.9% of the patients remaining in the same category, although findings for specific diagnoses within these categories ranged from 61.5% to 85.7%. The groups with unknown and nonspecific diagnoses showed less stability; the diagnoses of more than one-third of these patients remained unknown or nonspecific at the 6-month evaluation. If the 6-month diagnoses are used as the research standard, somewhat lower percentages of patients received the same diagnoses at baseline. Forty-three percent of the changes in diagnosis were attributed to the clinical course of illness; the rest were attributed to the diagnostic process itself. CONCLUSIONS: A longitudinal diagnostic assessment based on multiple sources of information is crucial for categorizing first-admission psychotic patients, particularly those who do not initially fit into a DSM-III-R category. The short-term stability of a diagnosis is a function of multiple factors, including the changing clinical picture, additional sources of information, and new interpretations of original data.

Adolescent↗
PubMed1993

Escherichia coli strains involved in diarrhea in France: high prevalence and heterogeneity of diffusely adhering strains.

Two hundred sixty-two strains of Escherichia coli isolated from diarrheal stool specimens from infants, children, and adults hospitalized in Clermont-Ferrand, France, were studied to classify them in the previously described pathogenic groups of E. coli involved in diarrheal diseases. A total of 1.5% of them belonged to the enterotoxigenic E. coli pathotype, but none belonged to the enteroinvasive E. coli, enterohemorrhagic E. coli, or enteropathogenic E. coli pathotypes. Seventeen strains (6.5%) exhibited an aggregative pattern of adhesion to HEp-2 cells (EAggEC pathotype), but of these, three (17.6%) did not hybridize with the EAggEC DNA probe. Most of the strains involved in diarrhea belonged to the diffusely adhering E. coli group; 100 strains (38.2%) exhibited a diffuse adhesion (DA) to HEp-2 cells. Only eight strains (8.9%) from controls diffusely adhered to HEp-2 cells. The highly significant difference (P < 0.0001) between DA strains from patients and from controls suggests that the diffusely adhering E. coli strains should be considered pathogens. Only 33 of them (33%) hybridized with the previously described DA DNA probe, and only 2 (2%) hybridized with the AIDA DNA probe. Four different major proteins were observed in the bacterial surface extracts of the 33 strains positive with the DA DNA probe. In addition, 16 strains that diffusely adhered to HEp-2 cells induced a cytotoxic effect on HEp-2 cells that was characterized by pyknosis and lysis of the cytoplasmic membrane. This cytotoxic effect was correlated with the synthesis of a hemolysin. The genes involved in diffuse adhesion to HEp-2 cells were located on conjugative R plasmids in strains that did not hybridize with the DA or AIDA DNA probes.

Bacterial Adhesion↗
PubMed1993

An unusual cause of cerebral venous thrombosis in a four-year-old child.

BACKGROUND AND PURPOSE: Inherited protein S deficiency has been associated with an increased risk of thromboembolic disease. It is possible that such a coagulopathy could predispose children to the development of strokes by permitting clot formation in response to stimuli that ordinarily would be insufficient to cause thrombus formation. CASE DESCRIPTION: We evaluated a previously well 4-year-old boy who developed cerebral venous thrombosis after suffering minor head trauma. Crossed-immunoelectrophoresis of his plasma showed a marked decrease of the free, active form of protein S. Family studies revealed that the patient's father and other paternal relatives had a similar abnormality of protein S. CONCLUSIONS: We suggest that the cerebral venous thrombosis in this child was initially precipitated by minor head trauma and pathological thrombus formation was then potentiated by inherited protein S deficiency. This case extends the clinical spectrum for protein S deficiency and emphasizes the importance of evaluating family members to establish a specific diagnosis and therapeutic intervention.

Blood Coagulation↗
PubMed1992

R-plasmid-encoded adhesive factor in Klebsiella pneumoniae strains responsible for human nosocomial infections.

Klebsiella pneumoniae strains involved in hospital outbreaks of nosocomial infections, such as suppurative lesions, bacteremia, and septicemia, were resistant to multiple antibiotics including broad-spectrum cephalosporins. Epidemiologic investigations revealed that the reservoir for these K. pneumoniae strains was the gastrointestinal tracts of the patients. The study of the adherence ability of the strains reported here showed that these bacteria adhered to the microvilli of the Caco-2 cell line. This adhesion was mediated by a nonfimbrial protein with a molecular mass of 29,000 Da designated CF29K. Pretreatment of bacteria with antibodies raised against CF29K or Caco-2 cells with purified CF29K prevented the adhesion of K. pneumoniae strains to Caco-2 cells. CF29K immunologically cross-reacted with the CS31A surface protein of Escherichia coli strains involved in septicemia in calves. Genes encoding CF29K were located on a high-molecular-weight conjugative R plasmid, which transferred to E. coli K-12. Transconjugants expressed a large amount of CF29K protein and adhered to the brush border of Caco-2 cells. These findings show that K. pneumoniae strains were able to colonize the human intestinal tract through a plasmid-encoded 29,000-Da surface protein. Hybridization experiments indicated that the gene encoding resistance to broad-spectrum cephalosporins by the production of CAZ-1 enzyme and the gene encoding the adhesive property to intestinal cells were both located on a 20- to 22-kb EcoRI restriction DNA fragment. Genes encoding aerobactin and the ferric aerobactin receptor were also found on this R plasmid.

Bacterial Adhesion↗
PubMed1991

Peri-operative colonoscopy detects synchronous tumours in patients with colorectal cancers.

The aim of this study was to assess the value of colonoscopy as a peri-operative investigation in patients treated for colorectal cancer by surgical excision. Patients (134 male, 83 female) undergoing curative resection for colorectal carcinoma between August 1984 and January 1989 had colonoscopy within 3 months of surgery. Eleven patients (5%) had a synchronous cancer, which was diagnosed by colonoscopy in eight. In six of these eight, the diagnosis was made after surgery and 3 patients needed a second colectomy. However, in 3 patients the synchronous cancer was removed endoscopically without the need for further surgical resection. Most synchronous cancers had an earlier pathological stage than the index tumour. The rate of synchronous cancers was higher in patients with synchronous benign polyps (16%) than in those without polyps (3%). Colonoscopy is clearly justified as a peri-operative investigation in all patients undergoing potentially curative resection of colorectal cancer. If possible, the examination should be carried out prior to surgery, to guide the extent of resection.

Adult↗
PubMed1991

[Factors intervening in the variations of in vitro adhesion power of enterotoxinogenic colibacillus (ETEC) to human enterocytes].

Human enterotoxigenic Escherichia coli adhere to the brush border of human enterocytes. The mean number of bacteria adhering to one enterocyte (adhesion index) varied from 0.5 to 3.1 when the strains produce adhesins. Different factors related to enterocytes and to bacteria are involved in this variability. The number of bacteria which adhered to enterocytes issued from the same donor varied from from 0 to 12. Moreover the proportion of enterocytes on which several bacteria sticked did not exceed 20%. This variability might be due to the disparity in the maturation of the enterocytes. On the other hand, whatever the adhesion factors considered, the adhesion index varied according to the donors. ETEC strains did not express adhesion when bacteria were grown in a liquid medium but this capacity could be restored after transfer on solid medium. This phenomenon seemed like a phase-variation and appeared to be linked to a 4 to 6 kilobases (kb) plasmid. On the other hand, when the bacteria were grown on agar medium (CFA-agar or Mueller-Hinton agar) two phenotypes of colonies could be observed: large colonies (LC) which were composed of non-adhesive bacteria and small colonies (SC) which were composed of a majority of adhesive bacteria; when the number of subcultures was not too great, a majority of colonies presented the small colonies phenotype. The plasmid content analysis showed the segregation of a high molecular weight plasmid DNA (approximately 100 kb) for the bacteria issued from large colonies phenotype.

Age Factors↗
PubMed1990

Adhesion of enterotoxigenic Escherichia coli to the human colon carcinoma cell line Caco-2 in culture.

Enterotoxigenic Escherichia coli (ETEC) strains possessing colonization factor antigen I (CFA/I), CFA/II, CFA/III, and antigen 2230 were tested for their ability to adhere to the following cell lines: HeLa, HEp-2, HRT 18, Hutu 80, MDBK, MDCK, Vero, and Caco-2. ETEC strains adhered only to the Caco-2 cell line. Irrespective of the known adhesive factors, the ETEC strains that adhered to the brush border of human enterocytes also adhered to the Caco-2 cell line. The negative variants, which were cured of the plasmid encoding the adhesive factor, did not adhere. Adhesion of ETEC strains no longer occurred when the Caco-2 cells were pretreated with the homologous colonization factor antigen or when the bacterial cells were pretreated with homologous antibodies raised against the adhesive factors. This indicates that this adhesion is specific and that a different receptor exists for each type of adhesion factor. Electron micrographs of cross sections of the monolayer showed that the adhesion of ETEC strains to the brush border microvilli does not induce any lesion. Therefore, the Caco-2 cell line behaves in the same way as human enterocytes do.

Antigens, Bacterial↗
PubMed1989

Adhesive properties of enteropathogenic Escherichia coli isolated from infants with acute diarrhea in Africa.

The adhesive properties of 69 enteropathogenic Escherichia coli (EPEC) strains were studied. The strains were isolated from diarrheal stools of infants in Burundi, Africa, and identified by serotyping with 12 classical EPEC O serogroup antisera. A test for adhesion to HEp-2 cells revealed that 52% of the strains showed localized adherence and 13% diffuse adherence. Localized adherence phenotype was found in previously described serogroups O86, O111, O125, O127, O128 and O142; strains belonging to another serogroup, O126, also exhibited localized adherence. Use of an EPEC adherence factor DNA probe in colony hybridization and in Southern blot techniques revealed that all strains exhibiting localized adherence and no strain exhibiting diffuse adherence produced a positive reaction; the genes were localized on high molecular weight plasmids (50-70 megadaltons). In vitro adhesion tests with human enterocytes performed concurrently with all 69 strains showed that only six of them adhered. These strains belonged to the O26, O117, O125, O128 and O142 serogroups. The adhesin CFA/I was detected only in the O128 Escherichia coli. The strain of serogroup O142 exhibited both adhesion to human enterocytes and localized adherence to HEp-2 cells, which suggests that the adhesive systems of enterotoxigenic and enteropathogenic Escherichia coli may coexist.

Bacterial Adhesion↗
PubMed1989

[Inhibition by nifurzide of the adhesion capacity of enteropathogenic colibacillus to HEP-2 cells].

Enteropathogenic Escherichia coli (EPEC) adhere in vivo to enterocytes. This adhesion capacity can be obtained in vitro with Hep-2 cells on which a characteristic localized adherence (LA) is observed. We studied the effect of subinhibitory concentrations (SIC) of nifurzide, a nitrofurane derivative, on this bacterial adherence phenomenon. Three EPEC strains are used: 11201 (026 serogroup), 7958 (0128) and 7836 (0142). Various SIC (MIC/2; MIC/4;...; MIC/32) were added either to the culture medium of bacteria or to the Eagle medium in which bacteria and Hep-2 cells were mixed during the adhesion experiments. In each case an adhesion index is determined. Nifurzide strongly inhibits the adherence capacity of the three strains when concentrations ranging from MIC/2 to MIC/16 where added in both culture media. On the other hand three other nitrofurane derivatives which have no antibacterial effect did not inhibit adherence. The mechanism of the adherence inhibition by nifurzide is discussed.

Anti-Bacterial Agents↗
PubMed1988

Characterization of Haemophilus influenzae isolated from patients with otitis media.

Two hundred and twenty-three Haemophilus influenzae strains isolated from patients with otitis media throughout France were characterized by biotype, serotype, antibiotic susceptibility, type of beta-lactamase production and human erythrocyte agglutination properties. All strains fell in one of two groups. One group consisted of encapsulated type b strains, 50% of which were biotype I, often resistant to ampicillin (38.5% of beta-lactamase producing strains) and seldom positive for haemagglutination (3.8%). The second group was composed of non-encapsulated strains, 42% of which were of biotype II, 10.6% beta-lactamase producers and 10.5% positive for haemagglutination.

Adolescent↗