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Biomedical subjects

M Hopp

Publications and source records attributed to M Hopp.

At least 19 recordsLinked to original sources
PubMed2005

Membranes for biohybrid liver support: the behaviour of C3A hepatoblastoma cells is dependent on the composition of acrylonitrile copolymers.

Co-polymers based on acrylonitrile, N-vinylpyrrolidone, aminoethylmethacrylate and sodium methallylsulfonate were used to prepare flat membranes by phase inversion. The surface properties of membranes were characterised by water contact angle measurements, atomic force microscopy and X-ray photoelectron spectroscopy (XPS). Membrane permeability was estimated by porosity measurements with water as test liquid. Human C3A hepatoblastoma cells were plated on these materials. Cell-material interaction was characterised by overall cell morphology, formation of focal adhesion contacts and intercellular junctions. Furthermore, cell proliferation was measured and compared with the functional activity of cells as indicated by 7-ethoxycoumarin-O-deethylation. More hydrophilic materials reduced spreading of cells, formation of focal adhesion and subsequent proliferation while homotypic cell adhesion was facilitated in correlation with stronger expressions of intercellular junctions and improved functional activity. In contrast, membranes with stronger adhesivity enhanced cell proliferation but reduced the functional activity of cells. It was concluded that the co-polymerisation of acrylonitrile with hydrophilic co-monomers, such as N-vinylpyrrolidone, could be used to tailor membrane materials for the application in biohybrid liver support systems.

Acrylonitrile↗
PubMed2003

Testing the cytotoxicity of metal alloys used as magnetic prosthetic devices.

Technical magnetic materials are increasingly used for the development of magnetic retained dental prosthetic and orofacial epithetic devices. Since most of the magnets based on rare earth metals, such as samarium-cobalt based alloys have a high tendency for corrosion they were first coated by tin and then encapsulated by titanium. However, the high mechanical load particularly on dental devices may cause a rupture of the titanium capsule and the alloys contact directly biological fluids. Hence, it is important to know the cytotoxicity of these magnets to assess their potential effects on the surrounding tissue. In this study, the cytotoxicity of neodymium-iron-boron and samarium-cobalt (plain, tin and titanium coated) magnets was tested. First, magnets were incubated up to 7 days in culture medium to prepare extracts for cytotoxicity measurements. Changes in the surface morphology due to corrosion were visualized by scanning electron microscopy and analysis of the elemental composition. 3T3 mouse fibroblasts were cultured in the presence of extracts and their viability measured by neutral red and metabolic assays. To learn more about a possible toxic activity of the main components of magnets, salt solutions of different concentrations resembling those elements, which are main constituents of the magnets, were used. 3T3 fibroblasts were also cultured in direct contact with the materials and material induced effects on cell morphology and growth monitored by microscopy. As a result of this study it was found that samarium-cobalt magnets have a strong tendency for corrosion and exert a considerable cytotoxicity. Neodymium-iron-boron magnets have a lesser tendency for corrosion and are only moderate cytotoxic. Coating of samarium-cobalt magnets with tin or titanium makes the materials non-toxic. Application of salt solutions shows that cobalt has a tendency to be cytotoxic at higher concentrations, but enhances cell metabolism and proliferation at lower concentrations while the other magnet constituents had a lower or negligible cytotoxic potential.

Journal Article↗
PubMed2002

First isolation of Trichophyton raubitschekii (syn. T. rubrum) in Europe.

Trichophyton raubitschekii is a rare dermatophyte which belongs to the Trichophyton rubrum species complex. Since 1981, only a few cases of dermatophytosis due to this anthropophilic causative agent were published. In this paper the authors report the first cases of Tinea corporis caused by Trichophyton raubitschekii (syn. T. rubrum) in Europe. The patients, one immigrant from Ghana and three from Cameroon, had typical lesions of tinea corporis. Four strains were isolated and characterized by conventional and molecular methods. On morphological and physiological grounds the isolates were identified as T. raubitschekii by the following phenotypical features: (1) velvety colony texture; (2) brown pigment; (3) abundant macroconidia and (4) positive urease activity. Molecular diagnostics were performed by single strand conformation polymorphism (SSCP) and sequence analysis of the ATPase9 intron of the mitochondrial (mt) DNA and the internal transcribed spacer (ITS) region of the rDNA, respectively. The ITS sequences and SSCP patterns of the ATPase9 intron were found to be identical among the four strains and also when compared to reference strains of T. rubrum. As shown in the present paper, T. raubitschekii is genetically identical to T. rubrum but differs in some phenotypical characteristics. Since misidentification with other dark-coloured dermatophyte variants is possible, medical mycologists should bear in mind the special morphological characteristics of T. raubitschekii (syn. T. rubrum) for future identifications.

Adenosine Triphosphatases↗
PubMed2001

Candida africana sp. nov., a new human pathogen or a variant of Candida albicans?

Atypical Candida strains were isolated from patients in Madagascar, Angola and Germany. These isolates were slow growing and were unable to produce chlamydospores. They had atypical carbohydrate assimilation profiles. All strains were unable to assimilate the amino sugars N-acteylglucosamine and glucosamine as well as the disaccharide trehalose and the organic acid DL-lactate. They were germ-tube-positive in serum, but only some of these organisms produced pseudohyphae after a long incubation. As shown by Fourier transform infrared spectroscopy the atypical Candida isolates clustered as a monophyletic group different from C. albicans and C. dubliniensis. All strains belonged to C. albicans serotype B. Considering all data presented here, this group of Candida strains differs from any other known member of the genus Candida. Therefore, it is suggested to represent a new species within the genus Candida for which the name Candida africana is proposed.

Angola↗
PubMed2001

Advanced integrated mouse YAC map including BAC framework.

Functional characterization of the mouse genome requires the availability of a comprehensive physical map to obtain molecular access to chromosomal regions of interest. Positional cloning remains a crucial way of linking phenotype with particular genes. A key step and frequent stumbling block in positional cloning is making a contig of a genetically defined candidate region. The most efficient first step is isolating YAC (Yeast Artificial Chromosome) clones. A robust, detailed YAC contig map is thus an important tool. Employing Interspersed Repetitive Sequence (IRS)-PCR genomics, we have generated an advanced second-generation YAC contig map of the mouse genome that doubles both the depth of clones and the density of markers available. In addition to the primarily YAC-based map, we located 1942 BAC (Bacterial Artificial Chromosome) clones. This allows us to present for the first time a dense framework of BACs spanning the genome of the mouse, which, for instance, can serve as a nucleus for genomic sequencing. Four large-insert mouse YAC libraries from three different strains are included in our data, and our analysis incorporates the data of Hunter et al. and Nusbaum et al. There is a total of 20,205 markers on the final map, 12,033 from our own data, and a total of 56,093 YACs, of which 44,401 are positive for more than one marker.

Algorithms↗
PubMed2000

Morphological study of Osteoplate 2000-extension implants after bending.

Unfavorable anatomical conditions of implant sites often require the insertion of implants in a direction that may interfere with the positioning of suprastructural elements in a functionally and esthetically satisfying manner. In some implant systems, bending of the implant neck is one of the possible methods for optimizing the insertion angle for the superimposed prosthesis. The aim of this study was to investigate whether bending procedures of the implant neck cause changes in the surface properties at the implant neck area. After bending of the implant neck up to 30 degrees, scanning electron microscopy revealed changes in the surface texture of the titanium. Superficial rips approximately 5 microns wide and 100 microns long had formed. These findings were confirmed by metallographic examinations. Values of Vickers hardness testing in the implant neck area after bending of 30 degrees showed significant differences between the compression or stretched zone and the neutral zone of the bending area. Bending of the implant neck between 0 and 20 degrees may influence the surface morphology, promoting superficial rips. Plaque accumulation and mechanically induced mucosal irritations due to changes of surface morphology and properties by bending should be further analyzed.

Acid Etching, Dental↗
PubMed1998

Characterization of the mouse Src homology 3 domain gene Sh3d2c on Chr 7 demonstrates coexpression with huntingtin in the brain and identifies the processed pseudogene Sh3d2c-ps1 on Chr 2.

Formation of intracellular protein complexes is often mediated by Src homology 3 domain-containing proteins interacting with proline-rich target sequences on other proteins. The Sh3d2c gene or its rat/human orthologs have been implicated in synaptic vesicle recycling due to interaction with dynamin I and synaptojanin in nerve terminals. In a yeast two-hybrid system, association with a huntingtin fragment containing an elongated stretch of polyglutamines was observed recently. By genetic mapping and fluorescence in situ hybridization we demonstrate the localization of Sh3d2c on mouse chromosome 7. A processed pseudogene of Sh3d2c, Sh3d2c-ps1, was identified and mapped to mouse chromosome 2. Using RNA in situ hybridization, we show that Sh3d2c is transcribed in various regions of the brain. The striatum, hippocampus, cortex, basal hypothalamus, brain stem, and cerebellum are the most prominent sites of expression. Because huntingtin and Sh3d2c are coexpressed in most regions of the brain, it can be speculated that there is a link between the association of huntingtin/Sh3d2c and the pathogenesis of Huntington disease.

Animals↗
PubMed1996

[Prerequisites for effective therapy of chronic recurrent vaginal candidiasis].

67 women with chronic recurrent or persistent vaginal candidosis between 5-79 years of age were seen in our outdoor department. In 34 cases, yeasts could be isolated in a vaginal swab taken at the first consultation. On average the patients reported 5 episodes per year during the last years. Typical symptoms consisted of pruritus vulvae, local inflammation and a curdy vaginal discharge. Nearly all of the women had received local or systemic antimycotic treatment for several times. In 53% (18 patients), C. albicans had been isolated, in 29% (10 patients) C. glabrata and in 9% (3 patients) C. krusei. While candidosis due to C. albicans and C. krusei was frequently associated with distressing complaints, infections with C. glabrata caused only very few symptoms. Independent of the species, severe and persistent infections were characterized by long term persisting specific IgM-antibody-titers and remarkable lack of IgG-antibodies. The laboratory parameters of WBC, CRP and immunelectrophoresis were normal. The minimum inhibitory concentrations (MIC) of 60 Candida strains against fluconacole were determined by microdilution assay. The MIC for C. albicans (n = 35) were between 0.78 and 3.125 micrograms/ml, for C. glabrata (n = 20) between 8 and 32 micrograms/ml and for C. krusei (n = 5) between 25 and 128 micrograms/ml. In 7 cases, local antimycotic treatment was sufficient. Correlating to the sensitivity, 18 women were treated with 100-800 mg fluconacole/d for 10-20 days. In 13 of them, clearance of symptoms and yeasts was achieved. The treatment of fluconacole-resistant strains with itraconazole (100-200 ml/d for 10-20 days) together with local application of nystatin (2 x 1 Mio. IE for 10 days) was without any effect. Three women with C. albicans, C. glabrata and C. krusei infection received a candidin-vaccination (0.005 BE/ml-500 BE/ml). In all of these cases, production of IgM-antibodies was induced. However, the clinical symptoms could not be influenced. Only in two cases it was not possible to reach a clearance of symptoms and yeasts. The results show the benefit of a precise differentiation before therapy. Serologic controls of antibody titers seem to be useful tools to control the efficacy of treatment.

Adolescent↗
PubMed1996

Outcome of Silicone Ring Vertical Gastroplasty in Patients Aged 50 Years and Older.

BACKGROUND: The authors studied the results Of silicone ring vertical gastroplasty (SRVG) in Patients aged 50 years and older. METHODS: The early and late Postoperative results in 28 patients aged.50 Years or older undergoing SRVG were reviewed retrospectively, The results were compared to those of 370 Patients Younger than 50 years operated during the same period. RESULTS: There was no Postoperative mortality among patients aged 50 years and older. There was a significantly higher incidence Of Pulmonary embolus and wound infection among patients aged 50 years and older (P < 0.05). The weight loss did not differ significantly between the two studied age groups. CONCLUSION: SRVG may performed on patients aged 50 years or older with acceptable complication rate and favorable postoperative results.

Journal Article↗
PubMed1996

Growth hormone receptor deficiency (Laron syndrome) in black African siblings.

Non-Caucasians with growth hormone receptor (GHR) deficiency/Laron syndrome among the approximately 180 recognised cases are rare, and include a Japanese and 3 African Americans. Black African siblings, a brother and a sister seen initially at 11 years 9 months and 5 years 6 months of age respectively were -7,4 and -8,0 on the standard deviation score for height. They had characteristic features and biochemical findings including prominent forehead; depressed nasal bridge; central adiposity; high-pitched voices; micropenis; high GH levels and low levels of insulin-like growth factor (IGF)-I, IGF-II, insulin-like growth factor-binding protein 3 (IGFBP-3), and GH-binding protein (the solubilised extracellular domain of the GH cell surface receptor). Molecular genetic studies revealed a dinucleotide deletion in both siblings on exon 7 of the GHR gene, a mutation not found in any other GHR-deficient patient studied, including the North Americans of African origin. Since African Americans have a substantial admixture of Caucasian genes, it is of interest to document the presence of this condition in siblings from Africa.

Adolescent↗
PubMed1993

Diverse growth hormone receptor gene mutations in Laron syndrome.

To better understand the molecular genetic basis and genetic epidemiology of Laron syndrome (growth-hormone insensitivity syndrome), we analyzed the growth-hormone receptor (GHR) genes of seven unrelated affected individuals from the United States, South America, Europe, and Africa. We amplified all nine GHR gene exons and splice junctions from these individuals by PCR and screened the products for mutations by using denaturing gradient gel electrophoresis (DGGE). We identified a single GHR gene fragment with abnormal DGGE results for each affected individual, sequenced this fragment, and, in each case, identified a mutation likely to cause Laron syndrome, including two nonsense mutations (R43X and R217X), two splice-junction mutations, (189-1 G to T and 71 + 1 G to A), and two frameshift mutations (46 del TT and 230 del TA or AT). Only one of these mutations, R43X, has been previously reported. Using haplotype analysis, we determined that this mutation, which involves a CpG dinucleotide hot spot, likely arose as a separate event in this case, relative to the two prior reports of R43X. Aside from R43X, the mutations we identified are unique to patients from particular geographic regions. Ten GHR gene mutations have now been described in this disorder. We conclude that Laron syndrome is caused by diverse GHR gene mutations, including deletions, RNA processing defects, translational stop codons, and missense codons. All the identified mutations involve the extracellular domain of the receptor, and most are unique to particular families or geographic areas.

Adolescent↗
PubMed1983

A demonstration of the cost benefits of case management services for discharged mental patients.

The authors report on a demonstration of the cost benefits of case management for hospitalized mental patients discharged from a New York State Community Mental Health Center to community living in a rural catchment area. Case managers promoted social rehabilitation and maximized time spent in the community. Comparison of the treatment group with matched controls on frequency and duration of rehospitalization during the 15 month intervention period shows a benefit conservatively estimated as 2.03 to 2.72, depending on size of case load.

Adult↗
PubMed1982

Fatal heat-stroke in a child taking appetite-suppressant drugs.

An 11-year-old girl who was taking two appetite-suppressant agents as part of a weight-reducing regimen developed heat-stroke while taking part in a 'nature hike' at an ambient temperature of 34 degrees C. The other 107 participating children suffered no significant ill-effects. Sympathomimetic amines used as appetite suppressants can produce heat intolerance by two mechanisms: they increase endogenous heat production as a result of their stimulatory effects on the central nervous system, and they impede the dissipation of heat from the body by producing peripheral vasoconstriction.

Child↗
PubMed1982

Congo-Crimean haemorrhagic fever in South Africa. Report of a fatal case in the Transvaal.

A 13-year-old boy, after having spent a week at a camp in a nature reserve in the western Transvaal, developed an acute illness of sudden onset characterized by chills, severe headache, muscle pains and high fever. On the 3rd day he developed a haemorrhagic state with profuse bleeding from the gastro-intestinal tract and other mucous membranes and petechial haemorrhages into the skin, from which he died on the 6th day after onset of the illness. A tick, identified as a species of Hyalomma, was found attached to his scalp. The provisional clinical diagnosis of Congo virus fever was confirmed in the laboratory by the isolation of the virus in newborn mice inoculated with the patient's blood. This is the first incrimination of Congo virus as the cause of a fatal case of haemorrhagic fever in South Africa, although it is known to occur in several countries in the tropical region of Africa and in south-eastern Europe and Asia.

Adolescent↗