Biomedical subjects

C Lehr

Publications and source records attributed to C Lehr.

9 recordsLinked to original sources

PubMed2004

Genetic and morphological differentiation in Tephritis bardanae (Diptera: Tephritidae): evidence for host-race formation.

The fruit fly Tephritis bardanae infests flower heads of two burdock hosts, Arctium tomentosum and A. minus. Observations suggest host-associated mating and behavioural differences at oviposition indicating host-race status. Previously, flies from each host plant were found to differ slightly in allozyme allele frequencies, but these differences could as well be explained by geographical separation of host plants. In the present study, we explicitly test whether genetic and morphological variance among T. bardanae are explained best by host-plant association or by geographical location, and if this pattern is stable over a 10-year period. Populations of A. tomentosum flies differed significantly from those of A. minus flies in (i) allozyme allele frequencies at the loci Pep-A and Pgd, (ii) mtDNA haplotype frequencies and (iii) wing size. In contrast, geographical location had no significant influence on the variance estimates. While it remains uncertain whether morphometric differentiation reflects genotypic variability or phenotypic plasticity, allozyme and mtDNA differentiation is genetically determined. This provides strong evidence for host-race formation in T. bardanae. However, the levels of differentiation are relatively low indicating that the system is in an early stage of divergence. This might be due to a lack of time (i.e. the host shift occurred recently) or due to relatively high gene flow preventing much differentiation at loci not experiencing selection.

Analysis of Variance↗

PubMed2000

Influences of process parameters on nanoparticle preparation performed by a double emulsion pressure homogenization technique.

The preparation of nanoparticles (NP) as an improved colloidal carrier system for proteins was investigated. Bovine serum albumin (BSA) was used as model drug. Owing to the high solubility of the protein in water, the double emulsion technique has been chosen as one of the most appropriate method. In order to both reaching submicron size as well as increasing the grade of monodispersity compared to previous preparation techniques, a microfluidizer as homogenization device was used. All experiments were performed using two biodegradable polymers, poly[D,L-lactic-co-glycolic acid] 50/50 (PLGA) and poly[epsilon-caprolactone] (PCL). The homogenization procedure has been optimized with regard to particle size and monodispersity by studying the influence of the homogenization time as well as the amount of polymer and surfactant in the external aqueous phase. The drug loading has been improved by varying the concentration of the protein in the inner aqueous phase. By increasing the protein concentration in the inner aqueous phase the polydispersity was slightly higher, while the particle size was not influenced significantly. The BSA encapsulation efficiency decreased with higher protein concentration in the inner aqueous phase. All release profiles were characterized by a initial burst effect, a higher release rate was obtained after 4 weeks for PLGA NP (60%) compared with PCL NP (47%).

Animals↗

PubMed2000

Characterization of microcapsules by confocal laser scanning microscopy: structure, capsule wall composition and encapsulation rate.

The potential of confocal laser scanning microscope (CLSM) has been evaluated for characterizing microcapsules. The aim was to visualize the polymer distribution within the particle wall, and to localize and to quantify the encapsulated oil phase. Microcapsules were prepared by complex coacervation: the oil phase, gelatine, and arabic gum were labelled with fluorescent markers. For all compounds it was proved that fluorescence labelling did not alter physico-chemical properties critical to the encapsulation process. Labelling of the inner oil phase allowed us to identify and to localize, three-dimensionally, the encapsulated compound. A homogeneous distribution for both gelatine and arabic gum throughout the capsule wall was observed. The addition of fluorescently labelled casein as a macromolecular model compound to the coacervate resulted in an inhomogeneous distribution of casein within the wall material, the highest concentration of casein was found at the oil-wall interface. To determine the encapsulation rate, CLSM pictures of the microcapsule samples were acquired using different fluorescence labels for the microcapsule wall polymers and the incorporated oil phase, respectively. By applying computational image analysis, the volumes of the different phases were calculated. Comparing the results of non-destructive image analysis with those obtained by degradation, extraction and chemical analysis, a linear relation was found with correlation coefficients better than 0.980.

Capsules↗

PubMed1999

Biodegradable monodispersed nanoparticles prepared by pressure homogenization-emulsification.

The aim of the present work was to investigate the preparation of nanoparticles (NP) as potential drug carriers for proteins. The hydrophilic protein bovine serum albumin (BSA) was chosen as the model drug to be incorporated within NP. Owing to the high solubility of the protein in water, the double emulsion technique has been chosen as one of the most appropriate method. In order to reach submicron size we used a microfluidizer as a homogenization device with a view to obtaining NP with a very high grade of monodispersity. Two different biodegradable polymers, poly[D, L-lactic-co-glycolic acid] 50/50 (PLGA) and poly[epsilon-caprolactone] (PCL) has been used for the preparation of the NP. The drug loading has been optimized by varying the concentration of the protein in the inner aqueous phase, the polymer in the organic phase, the surfactant in the external aqueous phase, as well as the volume of the external aqueous phase. The BSA encapsulation efficiency was high (>80%) and release profiles were characterized by a substantial initial burst release for both PLGA and PCL NP. A higher release was obtained at the end of the dissolution study for PLGA NP (92%) compared with PCL NP (72%).

Biocompatible Materials↗

PubMed1997

[Position identification in knee joint endoprosthesis].

In this paper we present a method for measuring the wear of the polyethylene inlay in knee joint endoprostheses from standard X-ray images. Our approach is to estimate the spatial position of the tibial and femoral components of the prostheses from their contours in the X-ray image. When we know the exact shape of these two components, we can calculate the minimal spatial distance between them which approximates the remaining thickness of the inlay. First results show that this approach might provide sufficient accuracy for the given task.

Biometry↗

PubMed1986

Pathogenicity and immunogenicity of piliated and nonpiliated phases of Moraxella bovis in calves.

Pathogenicity evaluations of Moraxella bovis strain EPP 63 grown in the piliated and nonpiliated phase indicated that the organism grown in the piliated phase induced clinical keratoconjunctivitis, whereas the organism grown in the nonpiliated phase did not induce disease under identical challenge conditions. Calves inoculated with culture grown in the piliated phase developed significantly (P less than 0.01) higher lesion scores than did calves inoculated with culture grown in the nonpiliated phase. Vaccination/challenge exposure evaluations indicated that calves immunized with vaccine prepared from piliated culture had significantly lower lesion scores than did control calves (P less than 0.001) or calves immunized with vaccine prepared from nonpiliated culture (P less than 0.05). Similarly, calves immunized with piliated vaccine developed a significantly higher antibody titer against purified pili. Nonvaccinated controls and calves immunized with nonpiliated vaccine did not develop a significant increase in antibody titer. The results indicate that M bovis pili constitute an important factor in the pathogenicity of keratoconjunctivitis and may be used as a vaccine in the control of keratoconjunctivitis in cattle.

Animals↗

PubMed1985

Serologic and protective characterization of Moraxella bovis pili.

This study was conducted to determine the protective nature of purified M. bovis EPP 63 pili in controlling experimentally induced Infectious Bovine Keratoconjunctivitis, and to determine antigenic similarity of pili isolated from various M. bovis isolates. Ten calves were vaccinated twice, 28 days apart, with 5.0 mg (protein) EPP 63 purified pili. Ten calves were maintained as non-vaccinated controls. All calves were exposed to ultraviolet light prior to challenge. The calves were challenged by instilling approximately 2.0 X 10(8) CFU of EPP 63 piliated organisms into the conjunctival sac. Antisera to respective pili types were prepared by immunizing the rabbits with purified pili from M. bovis strains EPP 63, FLA 64, IBH 68, MED 72 and ATCC 10900. Rabbit serum was evaluated for cross reactivity by enzyme-linked immunosorbent assay (ELISA). Purity of pili preparations was demonstrated on SDS-PAGE gels. Molecular weight of pili subunit was determined to be approximately 20,000 for EPP 63, 19,500 for IBH 68 and ATCC 10900, and 17,500 for FLA 64 and MED 72. One of 10 (10%) calves vaccinated with EPP 63 purified pili, and 6 of 10 (60%) nonvaccinated controls developed IBK, respectively. Average eye scores for vaccinates and controls were 0.05 and 0.85, respectively. Significant cross-reaction was found between EPP 63 and MED 72 pili. FLA 64 and ATCC 10900 were similar; however, antiserum to IBH 68 pili showed some degree of cross reaction with other pili.

Animals↗

PubMed1978

Rare occurrence of a holoacardious acephalic monster: sonographic and pathologic findings.

Sonography is gaining increasing importance in the diagnosis of anomalies in utero. Findings such as anencephaly, hydrocephaly, sacrococcygeal teratoma, fetal ascites, and obstructive uropathy have been described. Detection of anomalies such as these are important in the management of the pregnancy and aid in the preparation for the postnatal care or treatment of the fetus. While this article deals with the dramatic findings of a grossly anomalous fetus of a twin pregnancy, the ultimate value of ultrasound is its potential for detecting correctable malformation in a safe, noninvasive, and harmless manner.

Abnormalities, Severe Teratoid↗

PubMed1976

Scleroderma and carcinoma of the lung.

Two cases of scleroderma and carcinoma of the lung are reported. The 16 previously reported cases in the English literature are reviewed and tabulated in an attempt to determine the pathological and clinical presentation of carcinoma of the lung superimposed on the sclerodermal lung. When patients with scleroderma develop a change in pulmonary symptoms, a superimposed cancer of the lung should be suspected. The relationship between interstitial pulmonary inflammatory disease and cancer of the lung is discussed.

Adenocarcinoma↗