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Biomedical subjects

J Hamel

Publications and source records attributed to J Hamel.

54 records · Page 3Linked to original sources
PubMed1987

A monoclonal antibody directed against a serotype-specific, outer-membrane protein of Haemophilus influenzae type b.

Monoclonal antibodies (Mabs) were produced against outer-membrane proteins (OMPs) of Haemophilus influenzae type b. The clones were screened by ELISA with outer-membrane preparations of H. influenzae type b and untypable strains as coating antigens. Antibodies directed against the proteins of mol. wt (10(3)) 43, 37 and 13 were identified by immunoblotting of SDS-PAGE patterns of OMPs. Proteolytic enzyme treatments of the OMPs resulted in reduction of Mab reactivity as measured by ELISA. Furthermore, the absence of reactivity of Mab Hb-2 with a preparation of lipopolysaccharide confirmed the protein nature of its corresponding epitope. Binding assays with live bacteria showed that Hb-2 reacted with a cell surface-exposed antigenic determinant. Mab Hb-2 was bactericidal in vitro in the presence of complement. The characterisation of Hb-2 (IgG2a) by Western immunoblotting analysis revealed that it was directed against the 37 X 10(3)-mol. wt OMP. In a dot-enzyme immunoassay, Hb-2 reacted specifically with 326 strains of H. influenzae type b. It did not cross-react with the other serotypes or untypable strains of H. influenzae or with other bacterial species. This is the first report of a monoclonal antibody identifying a serotype-specific surface-exposed OMP of H. influenzae type b.

Antibodies, Monoclonal↗
PubMed1987

Identification of Haemophilus influenzae type b by a monoclonal antibody coagglutination assay.

A coagglutination assay using monoclonal antibody is described for the identification of Haemophilus influenzae type b. An immunoglobulin G2a monoclonal antibody, Hb-2, directed against a serotype-specific outer membrane protein of H. influenzae type b was adsorbed to Staphylococcus aureus Cowan 1 cells. In a dot enzyme immunoassay, Hb-2 reacted with 453 of 455 H. influenzae type b isolates and did not react with H. influenzae of other serotypes, untypeable H. influenzae strains, or other bacterial species. The Hb-2 coagglutination assay was evaluated by testing 136 H. influenzae type b strains selected on the basis of multilocus enzyme genotypes, 5 strains of another serotype, and 94 untypeable H. influenzae strains. The specificity of the coagglutination assay was demonstrated by the inhibition of the reaction by free Hb-2 monoclonal antibodies. The coagglutination assay was as specific as the dot enzyme immunoassay and can be rapidly performed and easily interpreted.

Agglutination Tests↗
PubMed1986

Rapid diagnosis of severe Haemophilus influenzae serotype b infections by monoclonal antibody enzyme immunoassay for outer membrane proteins.

A highly sensitive and specific enzyme immunoassay (EIA) for the detection of Haemophilus influenzae serotype b antigens in body fluids and broth cultures was developed, with a polyclonal antibody directed against polyribose phosphate as the solid-phase reagent and a biotinylated monoclonal antibody directed against H. influenzae type b outer membrane protein as the liquid-phase reagent. H. influenzae type b antigens could be detected in broth cultures containing as little as 50 organisms per ml. The sensitivity and specificity of this system were compared with those of two commercial kits and counterimmunoelectrophoresis. The overall detection of H. influenzae type b antigens in clinical specimens collected from children infected with H. influenzae type b was as follows: with Phadebact, 86 and 86% in cerebrospinal fluid and urine specimens, respectively; with Bactigen, 86, 80, and 92%, with counterimmunoelectrophoresis, 78, 73, and 75%, and with biotin-avidin EIA, 100, 100, and 100% for cerebrospinal fluid, serum, and urine specimens, respectively. In the biotin-avidin EIA, no positive reactions were noted in specimens collected from patients infected with other bacteria or from patients without evidence of bacterial infection, whereas false-positive reactions were found by counterimmunoelectrophoresis and the commercial kits. These results suggest that this monoclonal antibody reacting with the outer membrane protein is more specific and sensitive than the conventional methods using polyclonal antisera for the detection of H. influenzae type b antigens during severe infections in children.

Antibodies, Monoclonal↗
PubMed1986

Mouse models of infection for Neisseria meningitidis B,2b and Haemophilus influenzae type b diseases.

A disseminated and fatal infection was established in C57BL mice, injected intraperitoneally with either Neisseria meningitidis B,2b or Haemophilus influenzae type b bacteria plus enhancement factors. The effects of mucin, hemoglobin, and iron dextran as enhancement of bacterial infectivity in mice were evaluated individually and in combination. A mixture of mucin and hemoglobin was most effective in enhancing the virulence of the pathogens. Inbred mouse lines were more susceptible than outbred ones. Relative virulence of a number of bacterial strains was also compared in one selected mouse line. Neisseria meningitidis B,2b and Haemophilus influenzae type b strains were more virulent than non-B,2b and nontypable strains. Finally, the course of bacteremia for the two infections in mice was followed by quantitative blood cultures. The animals succumbed to the generalized condition within 72 h. In the case of Neisseria meningitidis B,2b, 10 organisms with 4% mucin and 1.6% hemoglobin were sufficient to kill 50% of the animals. For Haemophilus influenzae type b, 300 bacteria with 5% mucin and 2% hemoglobin were necessary to obtain similar effects.

Animals↗
PubMed1985

Physicochemical characterization of human fibroblast migration inhibitory factor.

We recently reported a new lymphokine activity that affects fibroblasts by inhibiting their spontaneous migration. Human fibroblast migration inhibitory factor (FIF) obtained from concanavalin A (Con A)-stimulated human lymphocytes was characterized by Sephadex gel filtration and by enzyme treatment. FIF was found to be stable at 56 degrees C for 15 min but destroyed at 80 degrees C or at pH lower than 5. Gel filtration revealed two peaks of FIF activity 15,000 and at 34,000 Da. FIF activity was lost following treatment with trypsin, chymotrypsin, and neuraminidase and FIF could not be generated in the presence of inhibitors of glycosylation, suggesting that the molecule was a glycoprotein. FIF could be removed by adsorption to human fibroblasts but not to PMN, monocytes, or red blood cells. Further studies were carried out to investigate the role of sugars in the interaction of FIF with the target cells. Human FIF activity was significantly reduced in the presence of several sugars including alpha-methyl-D-mannoside, L-xylose, N-acetyl-D-glucosamine, D-mannose, L-rhamnose but not L-fucose. Preincubation of human fibroblasts with alpha-methyl-D-mannoside prevented their response to FIF. In contrast, pretreatment of fibroblasts with mannosidase had no effect, suggesting that alpha-methyl-D-mannoside was an essential component of the FIF molecule recognized by the FIF receptor on fibroblasts.

Cell Migration Inhibition↗
PubMed1985

Protection against infection with Neisseria meningitidis group B serotype 2b by passive immunization with serotype-specific monoclonal antibody.

Hybridomas derived from mice immunized with Neisseria meningitidis serogroup B serotype 2b (B,2b) outer membrane preparations produced monoclonal antibodies (MAbs) specific for major outer membrane proteins of classes 1, 2, and 5. The MAbs were examined by enzyme-linked immunosorbent assay against a selected panel of seven strains of N. meningitidis (B,2b) of different sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns, a serotype 2a, and a nontypable strain. The five MAbs selected were all bactericidal and of different immunoglobulin subclasses. None of the MAbs reacted with other bacterial strains in a dot-enzyme immunoassay. The corresponding antigenic determinant for each MAb was localized on a specific outer membrane protein by immunoblotting of sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of major outer membrane proteins. MAbs M5-11 and M5-30 bound to the class 2 protein and were serotype 2b specific. MAb M2-20 bound to the class 1 protein, and MAbs M5-16 and M5-19 bound to the class 5 protein. A mouse model of infection was established whereby a local infection progressed to lethal bacteremia over 3 days, and 50% of the animals were killed with an intraperitoneal injection of 10 meningococci plus 4% mucin and 1.6% hemoglobin. The ability of the MAbs to provide passive protection against experimental infection with N. meningitidis (B,2b) was examined. Both serotype-specific MAbs M5-11 and M5-30 were highly protective even though they were of different immunoglobulin subclasses. The class 5-specific MAb offered no protection, while the class 1-specific MAb gave limited protection. It may therefore be possible to provide protection against serotype 2b infection by using as vaccine the class 2 serotype-specific surface-exposed outer membrane protein epitopes defined by MAb M5-11 or M5-30.

Animals↗
PubMedDate not supplied

[Standardized ultrasound diagnosis (13 MHz) of the tendon of the posterior tibial muscle--normal findings in probands with healthy feet].

OBJECTIVES: Tibialis posterior dysfunction is often diagnosed at a very late stage. However, the early diagnosis of tibialis posterior dysfunction is crucial for therapeutic aspects and especially for the operative prognosis. The morphological correlate of the tibialis posterior dysfunction consists of degenerative changes and thickening of the posterior tibial tendon [2, 9, 11]. By means of a high frequency linear array transducer, a standardized technique of examination as well as reference values of cross-sections of posterior tibial tendon are introduced. MATERIAL AND METHODS: Investigating 51 healthy subjects (102 feet) without any foot deformities, standardized planes were defined by use of a 13 MHz linear array transducer in order to delineate the posterior tibial tendon. At exact anatomic landmarks, tendon diameters were measured using two longitudinal sections proximal and distal to the medial malleolus. Likewise, two diameters and the resulting roughly calculated cross-section of the tendon were determined, using two transverse sections at the level of the subtalar joint facet and the medial malleolus. The findings obtained by ultrasound in four female patients with the diagnosis of a tibialis posterior dysfunction confirmed during surgery are compared to the aforementioned 51 healthy subjects. RESULTS: A healthy tendon appears homogeneous and echo-rich in orthogonal ultrasound and displays average areas of 18.4 sq.mm. (SD 5.9 sq.mm.) at the subtalar joint facet level and 19.2 sq.mm (SD 4.8 sq.mm.) at medial malleolus level in transverse sections. The corresponding areas obtained in patients with tibialis posterior dysfunction were clearly enlarged than in healthy subjects. In 85% of all feet examined at the level of the medial malleolus, the tendon is surrounded by a hypoechoic halo which has a size smaller than two times the cross-section of the flexor digitorum longus tendon. CONCLUSION AND CLINICAL RELEVANCE: Reference values of tendon thickness and of intratendinous echo-structures at reproducible landmarks facilitate delimitations from pathological tendon alterations. The exact delineation of intratendineal echoes by high frequency array transducers and standardized examination techniques that measure tendons size is a prerequisite to enable an early assessment and registration of degenerative alterations and thickening of the posterior tibial tendon.

Adolescent↗
PubMedDate not supplied

[Clinical pedographic radiological findings after basal valgus osteotomy of metatarsal 1--a prospective study].

AIM: This study investigated the influence of valgusizing base wedge osteotomy of metatarsal 1 (MT 1) subsequently on the entire forefoot. METHOD: Pre- and post-operatively 22 cases were investigated between 1998 and 2000 both clinically and radiologically with pedographic analysis in 20 of these cases. RESULTS: According to the Kitaoka Score we could establish preoperative 37 and postoperative 72 out of 100 possible points. Following the MT 1-base wedge osteotomy with a distal soft-tissue procedure, the central forefoot region (MT 2/3) showed reduced pressure-induced pain, unchanged callus development, and reduced maximum load pressure. When the Plus-Index (MT 1 longer than MT 2) could be preserved in the valugusizing MT 1-base wege osteotomy, the metatarsalgia in the central forefoot region not only improved generally, but also the maximum loading pressure was clearly reduced. In cases with a post-operative Minus-Index (MT 1 shorter than MT 2), as well as in those Plus-Index cases undergoing a Keller procedure in the valgusizing base wedge osteotomy, the elevated pressure values in the central forefoot region persisted. CONCLUSION: In valgusizing MT 1-base wege osteotomy with preservation of the Plus-Index (MT 1 longer MT 2), metatarsalgia can be improved and the maximum loading pressure in the central forefoot can be reduced.

Adult↗
PubMedDate not supplied

[Sonographic diagnosis of the juvenile tarsus. Clinical application possibilities demonstrated by examples].

Radiologic assessment of foot deformities in young children is limited especially by the ossification status. Ultrasonography proved to be a useful diagnostic supplement e.g. in idiopathic talipes equinovarus, vertical talus, and tarsal coalitions. Effects of treatment and three-dimensional movements of the tarsal joint complex can be delineated. Sonographic assessment of tarsal alignment is applicable already in the first months of life. This study deals with first experiences in clinical application of this new diagnostic technique.

Ankle↗
PubMedDate not supplied

[Early and late results of physical therapy in lumbar disk prolapse].

The prognosis of conservative treatment of herniated lumbar discs is equivalent to operative treatment unless there is an absolute indication to operate. 85% of 58 patients with a proven herniated disc could be dismissed from the hospital in a satisfying condition, that is with working ability. 8 patients (12%) were operated, 3 of them at their own request. 2.5 years after the treatment in our hospital, a catamnesis of 30 patients showed positive results, only 4 patients had to undergo an operation.

Adolescent↗
PubMedDate not supplied

[A case of bilateral isolated talonavicular synostosis in childhood--observations of tarsal joint function and functional adaptation of the proximal ankle joint].

A rare case of bilateral isolated coalition of the talonavicular joint with ball and socket ankle joint is presented. Range of motion of the subtalar joint and hindfoot mobility were measured intraoperatively. The following conclusions may be drawn on development and function of the ankle joint complex: Isolated talonavicular synostosis in the growing foot results in marked impairment of subtalar range of motion. The development of a ball and socket ankle joint may be caused thereby, if tarsal hypomobility becomes effective at an early stage of growth.

Ankle Joint↗
PubMedDate not supplied

[Distribution and extent of hemophilic arthropathy in adulthood in severe factor VIII deficiency].

This study deals with the distribution and extent of hemophilic arthropathy in 52 adult patients suffering from severe hemophilia A. A clinical and radiological score-evaluation of knee, ankle and elbow joints was undertaken, 4.7 of 6 examined joints proved to be affected in the third life-decade in the average, the extent of destruction being most pronounced at the knee joints. A rather close correlation of clinical and radiological signs was found to exist only related to the knee joints.

Adolescent↗
PubMedDate not supplied

Global genetic structure and molecular epidemiology of encapsulated Haemophilus influenzae.

A collection of 2,209 isolates of six polysaccharide capsule types of Haemophilus influenzae, including 1,975 serotype b isolates recovered in 30 countries was characterized for electrophoretically demonstrable allele profiles at 17 metabolic enzyme loci. Two hundred eighty distinct multilocus genotypes were distinguished, and cluster analysis revealed two primary phylogenetic divisions. The population structure of encapsulated H. influenzae is clonal. Currently, most of the invasive disease worldwide is caused by serotype b strains of nine clones. Strains producing serotype c, e, and f capsules belong to single divisions and have no close genetic relationships to strains of other serotypes. Serotype a and b strains occur in both primary phylogenetic divisions, probably as a result of transfer and recombination of serotype-specific sequences of the cap region between clonal lineages. A close genetic relatedness between serotype d isolates and some strains of serotypes a and b was identified. There are strong patterns of geographic variation, on an intercontinental scale, in both the extent of genetic diversity and the clonal composition of populations of encapsulated strains. The analysis suggests that the present distribution of clones is, in part, related to patterns of racial or ethnic differentiation and historical demographic movements of the human host populations.

Alleles↗
PubMedDate not supplied

Effect of patient demand for drugs on physician prescribing.

In a controlled setting with symptoms and demographic variables held constant, differences in physicians' ratings of symptoms, diagnosis and prescribing of drugs were explored in response to six videotaped patients of differing age groups who either demanded drugs or presented somatic complaints. There was a 1.2:1 ratio of prescriptions given to female versus male patients; demand for drugs resulted in significantly lower prescription rates, drugs prescribed, and multiple prescriptions; and those patients who presented somatic complaints received significantly higher amounts of minor tranquilizers. Older patients were prescribed a significantly greater number of drugs than younger patients, particularly in the antidepressant classification, and differences in symptom ratings but not in prescription rates were seen between male and female physicians.

Adult↗