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Biomedical subjects

D Blohm

Publications and source records attributed to D Blohm.

At least 19 recordsLinked to original sources
PubMed2001

[Complications of transligamental knee arthroscopy. The frequency of pain and ultrasonographic changes in the inferior patellar tendon].

INTRODUCTION: We wanted to investigate whether the transtendineous portal for arthroscopy was causing damage to the patellar tendon (PT). We also wanted to assess postoperative complaints related to the patellar tendon. METHODS: Out of 59 consecutive patients, who had neither anterior knee pain nor ultrasonographic changes in the tendon, and who had a planned transtendineous arthroscopy of the knee because of a suspected meniscal lesion or osteoarthritis, 36 patients were given both a clinical examination and ultrasonography of the PT before surgery and at two and six months. RESULTS: At the six months follow-up, 20 patients had tenderness of the PT, which was fewer than at the two-month follow-up. Ten patients had signs of granuloma formation of the patellar tendon and four had signs of perifibrosis/peritendinitis on ultrasonography. There was no statistical correlation between tenderness of the patellar tendon and granuloma formation (p = 0.48, Fisher's exact test) or perifibrosis/peritendinitis (p = 0.78, Fisher's exact test). DISCUSSION: More than 25% of the patients showed granuloma formation on ultrasonography and more than 50% had complaints from the patellar tendon, but both the symptoms and the complaints seemed to decline over time. The consequences of the postoperative changes in the patellar tendon six months postoperatively are uncertain, as there was no statistical correlation between tenderness of the PT and the findings at ultrasonography. Further studies are recommended to investigate the changes in the PT when this method is used.

Arthroscopy↗
PubMed2001

Phylogenetic relationships within terrestrial mites (Acari: Prostigmata, Parasitengona) inferred from comparative DNA sequence analysis of the mitochondrial cytochrome oxidase subunit I gene.

Partial DNA and amino acid sequences translated from the mitochondrial cytochrome subunit I gene (408 bp) of 17 mite species have been used for analyzing the phylogenetic relationships within the terrestrial Parasitengona (Trombidia). Due to mutational saturation of the third codon position, only first and second codon positions and amino acid sequences were analyzed, applying neighbor-joining, maximum-parsimony, and maximum-likelihood tree-building methods. The reconstructed trees revealed similar topologies of taxa; however, the phylogenetic relationships could be convincingly resolved only within several trombidioid taxa. The proposed basic relationships within the Parasitengona, in particular those of Calyptostomatoidea, Smarididae, and Erythraeidae, were poorly supported in bootstrap tests. A comparison of the presented gene tree with a phylogenetic tree based upon traditional characters revealed only few contradictions in nodes only weakly supported by morphological data. The most astonishing result is the proposed early derivative position of Microtrombidiidae within the terrestrial Parasitengona.

Animals↗
PubMed2000

[Fractures of the pelvis--a survey of "nonunion" and "malunion" surgical results].

UNLABELLED: Nonunion (NU) and malunion (MU) of the pelvis are conditions of absent and malaligned healing of a previous pelvis fracture causing severe disabling symptoms. Reconstructive surgery of the pelvis is more demanding than treatment of the acute fracture. Ten cases of NU and/or MU of the pelvis were treated. Average time from injury to referral was 33 months. Initial treatment was conservative (seven patients), internal fixation (two patients) or combined internal and external fixation (one patient). Complaints were pain (ten patients), limp (eight patients), leg length difference (five patients) and sitting problems (seven patients). RESULTS: All patients showed radiological union. Nine patients had less or no pain at all. All eight with a preoperative limp showed improvement or no limp after surgery. Two of five still had minor leg length difference. All seven patients with sitting problems claimed relief or complete removal of sitting problems. It is concluded that patients with severe disabling symptoms from NU and/or MU can expect relief of symptoms by late correction of the pelvic deformity.

Adolescent↗
PubMed2000

Differentiation of newly described antarctic bacterial isolates related to Roseobacter species based on 16S-23S rDNA internal transcribed spacer sequences.

The 16S-23S rDNA internal transcribed spacer (ITS) of Roseobacter denitrificans, Roseobacter litoralis, Ruegeria algicola and strains of the recently described species Antarctobacter heliothermus and Roseovarius tolerans were analysed in order to examine DNA sequence variations and to draw conclusions about inter- and intraspecific relationships. A. heliothermus included four strains with an ITS fragment length of 1092 bp. Roseovarius tolerans was described on the basis of eight strains. Five of these harboured two ITS fragments of different lengths (959 and about 1100 bp), while the others had one fragment of either 1083 bp (two strains) or 1165 bp (one strain). ITS lengths of the related species Roseobacter denitrificans, Roseobacter litoralis and Ruegeria algicola were found to be 980, 984 and 1158 bp, respectively. Phylogenetic analyses of the DNA sequences allowed species affiliation of strains with sequence length differences of > 200 bp and recognition of relationships based on a well-supported ITS tree. The strains of A. heliothermus and Roseovarius tolerans each formed a monophyletic branch and they were separated from each other by Ruegeria algicola. This species was now clearly separated from Roseobacter denitrificans and Roseobacter litoralis, which corresponded to the new genus affiliation of Ruegeria algicola. These data were additionally supported by analyses of the structure, relative position and order of genes for tRNA(Ile) and tRNA(Ala) found within the ITS of each strain. Comparative DNA sequence analyses of ITS and 16S rDNA revealed limitations, on species and strain levels, with respect to the phylogenetic resolution of the 16S rDNA due to the limited number of informative (variable) sites, while ITS sequence analyses provided more variable and sufficiently conserved positions to discriminate between strains and to reconstruct their taxonomic relationships.

Alphaproteobacteria↗
PubMed1999

Self-assembly of DNA-streptavidin nanostructures and their use as reagents in immuno-PCR.

The self-assembly of bis-biotinylated double-stranded DNA and the tetravalent biotin-binding protein streptavidin (STV) have been studied by non-denaturing gel electrophoresis and atomic force microscopy (AFM). The rapid self-assembly reproducibly generated populations of individual oligomeric complexes. Most strikingly, the oligomers predominantly contained bivalent STV molecules bridging two adjacent DNA fragments to form linear nanostructures. Trivalent STV branch points occurred with a lower frequency and the presence of tetravalent STV was scarce. However, valency distribution, size and the exchange dynamics of the supramolecular aggregates were highly sensitive to stoichiometric variations in the relative molar coupling ratio of bis-biotinylated DNA and STV. The largest aggregates were obtained from equimolar amounts while excess STV led to the formation of smaller oligomers appearing as fingerprint-like band patterns in electrophoresis. Excess DNA, however, induces a complete breakdown of the oligomers, likely a consequence of the instability of STV conjugates containing more than two biotinylated DNA fragments. It was demonstrated that the oligomers can further be functionalized, for instance by the coupling of biotinylated immunoglobulins. Both pure and also antibody-modified DNA-STV oligomers were used as reagents in immuno-PCR (IPCR), a highly sensitive detection method for proteins and other antigens. Employment of the supramolecular reagents led to an approximately 100-fold enhanced sensitivity compared to the conventional IPCR procedure.

Base Sequence↗
PubMed1999

DNA Microarrays.

The complete human genes (ca. 100 000) as well as the whole spectrum of biological diversity should soon be able to be analyzed simultaneously by means of DNA microarrays using the fast technical advances that are occurring in this area. The particular strength of array analysis, typically based on the hybridization of nucleic acid probes attached to microchips with labeled RNA or DNA samples, results from the highly redundant measurement of many parallel hybridization events (see picture), which leads to an extraordinary level of assay validation.

Journal Article↗
PubMed1999

DNA-Directed immobilization: efficient, reversible, and site-selective surface binding of proteins by means of covalent DNA-streptavidin conjugates.

Covalent DNA-streptavidin conjugates have been utilized for the reversible and site-selective immobilization of various biotinylated enzymes and antibodies by DNA-directed immobilization (DDI). Biotinylated alkaline phosphatase, beta-galactosidase, and horseradish peroxidase as well as biotinylated anti-mouse and anti-rabbit immunoglobulins have been coupled to the DNA-streptavidin adapters by simple, two-component incubation and the resulting preconjugates were allowed to hybridize to complementary, surface-bound capture oligonucleotides. Quantitative measurements on microplates indicate that DDI proceeds with a higher immobilization efficiency than conventional immobilization techniques, such as the binding of the biotinylated proteins to streptavidin-coated surfaces or direct physisorption. These findings can be attributed to the reversible formation of the rigid, double-stranded DNA spacer between the surface and the proteins. Moreover, BIAcore measurements demonstrate that DDI allows a reversible functionalization of sensor surfaces with reproducible amounts of proteins. Ultimately, the simultaneous immobilization of different compounds using microstructured oligonucleotide arrays as immobilization matrices demonstrate that DDI proceeds with site selectivity due to the unique specificity of Watson-Crick base pairing.

Biotinylation↗
PubMed1999

Evaluation of single-stranded nucleic acids as carriers in the DNA-directed assembly of macromolecules.

Current developments in nanosciences indicate that the self-assembly of macromolecules, such as proteins or metallic nanoclusters, can be conveniently achieved by means of nucleic acid hybridization. Within this context, we here report on the evaluation of single-stranded nucleic acids to be utilized as carrier backbones in DNA-directed self-assembly. A microplate solid-phase hybridization assay is described which allows rapid experimental determination of the hybridization efficiencies of various sequence stretches within a given nucleic acid carrier strand. As demonstrated for two DNA fragments of different sequence, the binding efficiencies of several oligonucleotides depend on the formation of specific secondary structure elements within the carrier molecule. A correlation of sequence-specific hybridization capability with modeled secondary structure is also obvious from experiments using the fluorescence gel-shift analysis. Electrophoretic studies on the employment of helper oligonucleotides in the formation of supramolecular conjugates of several oligonucleotide-tagged proteins indicate, that structural constraints can be minimized by disruption of intramolecular secondary structures of the carrier molecule. To estimate the influences of the chemical nature of the carrier, gel-shift experiments are carried out to compare a 170mer RNA molecule with its DNA analogue. Ternary aggregates, containing two protein components bound to the carrier, are formed with a greater efficiency on the DNA instead of the RNA carrier backbone.

Base Sequence↗
PubMed1999

"Little league elbow"--acute traction apophysitis in an adolescent badminton player.

A case of an acute traction apophysitis, "little league elbow", in an adolescent badminton player is presented. After a period of intense badminton activity, the patient developed typical signs of inflammation related to his elbow. X-ray showed soft tissue calcifications and ultrasound showed intra-articular swelling and a possible apophysitis related to the elbow. After a period of immobilization followed by low activity he could return to normal sports activity.

Adolescent↗
PubMed1998

Fracture of the metacarpal head with 180 degrees longitudinal rotation. Case report.

A 61-year old man fell and sustained an intracapital fracture of the 3rd metacarpal bone with an unusual dislocation. Primary radiograph showed 180 degrees longitudinal rotation of the distal fragment. To reduce the fracture the metacarpophalangeal joint was opened and the fracture stabilised. The fracture healed after four weeks, and there was no sign of necrosis at the three month follow up.

Fractures, Closed↗
PubMed1997

[Compression of the urethra by an arthrotic cyst].

A case is presented of an osteoarthrotic cyst of the pubic symphysis with a diameter of 32 mm that caused urinating problems because of posterior dislocation and compression of the urethra. X-rays showed osteoarthrosis of the pubic symphysis, and the 56-year old woman had a history of separation of the pubic symphysis at the age of 28.

Cysts↗
PubMed1997

Fluorometric polymerase chain reaction (PCR) enzyme-linked immunosorbent assay for quantification of immuno-PCR products in microplates.

Immuno-polymerase chain reaction (immuno-PCR) allows the detection of protein amounts as low as a few hundred molecules. This enhanced sensitivity is useful for a variety of applications in analytical and biomedical sciences. Application of this technique as a routine method requires the rapid quantification of the PCR products, preferably as an automated readout by microplate-based assays. Here, three methods are compared for detecting such amplified products, i. e., direct staining with a fluorescent intercalating dye, an enzymatic assay utilizing doubly hapten-labeled products, and gel electrophoresis. The enzymatic assay, carried out with either chromogenic or fluorogenic substrate for enzymatic signal amplification, was found to be the most sensitive method. The optimized assay was tested in direct immuno-PCR assays for detecting immunoglobulins (IgG) from mouse and rabbit as well as in a sandwich immuno-PCR assay for detecting recombinant hepatitis B surface antigen (rec. HBsAg). Sensitivity limits were found to be as low as 15 fg (10(-19) mol) IgG, representing a 1000-fold enhancement compared to enzyme-linked immunosorbent assay detection, and about 70 fg (2 x 10(-18) mol) rec. HBsAg, improving the detection limit of currently available methods by a factor of about 700. The well-reproducible enzymatic amplification signal further enhances the sensitivity of immuno-PCR and should render the method suitable for routine laboratories.

Animals↗
PubMed1997

Expression of microtubule-associated proteins MAP2 and tau in cultured rat brain oligodendrocytes.

Oligodendrocytes in culture are characterized by large membranous sheets containing an elaborate network of microtubules. Microtubule-associated proteins (MAPs) participate in microtubule stability and the regulation of the cellular architecture. We have investigated the expression of two major groups of MAPs, MAP2 and tau, in cultured rat brain oligodendrocytes. Alternatively spliced isoforms of mRNAs encoding MAP2 and tau were assessed by means of reverse transcription and polymerase chain reaction using a newly designed set of MAP2- and tau-specific primers. The data were compared with data obtained with cultures of rat brain astrocytes and rat cerebral neurons, and adult rat brain. The results show that oligodendrocytes, similarly to neurons, express mainly MAP2c transcripts containing three microtubule-binding repeats. They also contain small amounts of MAP2b mRNA. Six low molecular weight tau isoforms, namely tau 1-6, have been described in the brain (Goedert et al. 1991). The major isoform of tau mRNA in oligodendrocytes was found to be tau 1, which represents a marker typical for immature neurons. Tau 2 and tau 4 isoforms were also detected, albeit at a very low level. Immunoblot analysis of oligodendroglia cell extracts confirmed the presence of tau protein. It migrates as a single polypeptide with an apparent molecular weight of approximately 55 kDa. In addition, oligodendrocytes express MAP2c protein, which migrates as a close double band with an apparent molecular weight around 70 kDa. Indirect immunofluorescence staining indicated that tau and MAP2 immunoreactivity was expressed in oligodendrocytes of immature and mature morphologies in the cell somata and cellular processes. Tau was particularly found in the end of the cellular extensions, and both proteins exhibited a distribution similar to myelin basic protein. Thus, oligodendroglia, like neuronal cells, contain microtubule-associated proteins, mainly MAP2c and the tau 1 isoform, although at a much lower level. The presence of these MAPs in myelin-forming cells further points to the functional significance of the cytoskeleton during oligodendrocyte differentiation, process outgrowth, and myelin formation.

Alternative Splicing↗
PubMed1997

Mucins (MUC1 and MUC3) of gastrointestinal and breast epithelia reveal different and heterogeneous tumor-associated aberrations in glycosylation.

In a comprehensive study, we examined the expression of the membrane and secretory mucins MUC1 and MUC3, respectively, in normal and neoplastic gastrointestinal and breast epithelia before and after specific alterations of their glycan structures by neuraminidase, alpha-fucosidase, or carbohydrate-specific periodate oxidation. MUC1 mRNA was also identified in normal colorectal tissues by in situ hybridization. The data revealed that normal colorectal epithelia express both MUC1 mRNA and protein, which were detectable after periodate oxidation with all tested MUC1-specific antibodies. During tumorigenesis in the colon, MUC1 became recognizable without periodate treatment concomitantly with highly dysplastic lesions and the malignant state. In the breast, in which MUC1 is detectable with most antibodies in normal epithelium as well as in carcinomas, staining could be enhanced by pretreatment with periodate and casually by enzyme treatments. MUC3 was detectable in normal and neoplastic colorectal tissues and was more intensely stained after periodate oxidation. It was absent in normal breast even after pretreatment but was expressed in seven of 20 breast carcinomas. Therefore, incomplete glycosylation, abnormal distribution, and ectopic expression of mucins are characteristics of malignancy. Periodate oxidation may be widely applicable to immunohistochemistry for examining changes in glycosylation and for detecting antigens masked by glycans.

Biomarkers, Tumor↗
PubMed1996

[Interposition of the extensor tendon in a subcapital metacarpal fracture].

A case of an irreducibled subcapital fracture of the fifth metacarpal bone caused by interposition of the extensor tendon to the fifth finger and the intertendineous connection between the fourth and the fifth extensor tendons is described. To reduce the fracture the surgeon had to remove interposed tissue.

Adult↗