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Biomedical subjects

W Koch

Publications and source records attributed to W Koch.

At least 19 recordsLinked to original sources
PubMed1992

[Spontaneous necrosis of the femoral condyle--new findings in T2-weighted spin-echo sequences and gradient-echo studies].

The spontaneous necrosis of the femur condyles might cause diagnostic problems because clinical symptoms precede the radiologic changes on conventional x-ray. MRI offers an early detection of the necrosis of the femur condyle like bone necrosis of other localisation. Nine patients were examined by T1- and T2-weighted spin echo- and by T2*-weighted gradient echo sequences. All patients had reduced signal intensity in the subchondral bone marrow on T1-w SE sequences. In three patients new findings were observed on T2-w SE and gradient echoes respectively. These findings allow better understanding in the underlying pathologic-anatomical changes.

Aged↗
PubMed1992

[Dynamic functional MRT of the cervical spine].

To obtain functional studies of the cervical spine, a device has been developed which allows MRI examinations to be carried out in five different degrees of flexion. T1 and T2* weighted FFE sequences were used. Dynamic functional MRI was performed on 5 normals and 31 patients (5 disc herniation, 4 whiplash injuries, 6 spinal canal stenoses, 14 laminectomies and spinal fusions, 2 rheumatoid arthritis). The relationship of the spinal cord to the bony and ligamentous components in different degrees of flexion was particularly well shown in whiplash injury, spinal stenosis and postoperative situations.

Cervical Vertebrae↗
PubMed1991

Primary structure and expression of the Xenopus laevis gene encoding annexin II.

Annexin II (AnxII) is one of the Ca(2+)-dependent membrane- and phospholipid-binding proteins (annexins) which are encoded by a multigene family. AnxII was originally described as a major cellular substrate for the tyrosine kinase encoded by the src oncogene, and is also phosphorylated by protein kinase C in vivo and in vitro. To obtain more information about structurally conserved regions in AnxII, which could be of structural and/or functional importance, we have identified AnxII in a nonmammalian species, the clawed toad Xenopus laevis. In a ligand overlay assay, we employed p11, the cellular protein ligand of AnxII, to show that a 36-kDa Anx capable of binding p11 is present in a cellular extract from X. laevis cells. The cDNA cloning and sequence analysis revealed that two types of AnxII mRNA are expressed in X. laevis. The transcripts are highly similar to each other, but are encoded by two different genes. The deduced amino acid sequences show a high degree of conservation when compared to the sequences of mammalian and chicken AnxII. In particular, the p11-binding domain, as well as the protein core, which harbors the binding sites for Ca2+ and phospholipid, are highly similar. However, Tyr23, which is phosphorylated by pp60src in mammalian and chicken AnxII, is replaced by a Leu residue in both X. laevis molecules. Thus, tyrosine phosphorylation is probably not a general mode of regulation of AnxII function(s).

Amino Acid Sequence↗
PubMed1991

The E alpha promoter: a linker-scanning analysis.

To accurately delineate the DNA sequence elements involved in the transcriptional regulation of the murine MHC class II gene E alpha, we have constructed a set of "linker-scanning" mutants of the E alpha promoter region. These were made by the gapped heteroduplex technique and result in a set of 10-bp replacement mutations, covering the -206 to -6 stretch of the promoter. The effect of these mutations on transcriptional activity was evaluated in several systems, either by transfection into cultured cells or by in vitro transcription. The data points to the now classical X and Y boxes as the most important control elements, either for constitutive expression in B lymphoma cells, or for IFN-gamma-inducible expression in macrophages. Motifs upstream of the X box also play a role, but are somewhat less critical. Overall, we find no marked difference between regulatory strategies in B lymphomas or activated macrophages.

Animals↗
PubMed1991

Multiple simian virus 40 enhancer elements mediate the trans-activating function of the X protein of hepatitis B virus.

Transient transfections of tissue culture cells with plasmids encoding the X protein of hepatitis B virus result in a transcriptional trans-activation of certain target genes. Our experiments reveal that several individual simian virus 40 enhancer elements and a control element present in the mouse major histocompatibility class I gene H-2Kb are able to mediate the trans-activating function of the X protein. The data suggest that known cellular transcription factors that bind specifically to the multiple enhancer elements participate in trans-activation.

Base Sequence↗
PubMed1991

Experimental examinations concerning the problem of deformed emerging bees after infestation with Varroa jacobsoni.

The deformations of bees occurring in connection with varroatosis was examined both in case of natural and artificial infestation. Under both conditions, the number of bees showing wing deformations increased with the degree of mite infestation. Shortened abdomina, however, only appeared in the case of natural infestation. Inadequate brood care in colonies severely infested by Varroa mites is supposed to be responsible. Wing deformations could be produced by experimental haemolymph extraction.

Animals↗
PubMed1990

Analogous effects of organic calcium antagonists and magnesium on the epiphyseal growth plate.

High doses of both calcium antagonists and magnesium lead to disorders in the early phase of calcification. Analogous to known mechanisms of calcification outside the bone, the calcium overload of cellular suborganelles, which may play a role in enchondral ossification, is assumed to be prevented or delayed by calcium antagonists and magnesium. In accordance with the relevant literature, which describes analogous cytoprotective effects of calcium antagonists and magnesium in association with extraskeletal calcification and ossification, the qualitative agreement of histologic findings in the epiphyseal growth plate suggests a homologous, primarily intracellular mechanism of action of both magnesium and organic calcium antagonists. This common mechanism of action of the two substances on the molar Mg-Ca quotient, with reference to intracellular calcium phosphate mineralization, is regarded as the cause of the analogous effects.

Animals↗
PubMed1989

Anatomy of a new B-cell-specific enhancer.

The major histocompatibility complex class II molecules, like the immunoglobulins, are prominent B-lymphocyte markers. Herein, we describe a B-cell-specific enhancer associated with the murine class II gene, Ek alpha. This enhancer has a complex anatomy that suggests interactions between remotely spaced elements. Of particular interest is the finding that two CCAAT boxes spaced one kilobase apart are important for enhancer activity. Somewhat surprisingly, the E alpha and immunoglobulin enhancers seem to show little resemblance.

Animals↗
PubMed1989

The role of combined composite resection and irradiation in the management of carcinoma of the oral cavity and oropharynx.

Squamous cell carcinoma of the oral cavity and oropharynx can invade the mandible requiring an "en bloc" or composite resection. With this procedure alone, reported local control rates for advanced stage tumors have been suboptimal suggesting the need for adjuvant therapy. The treatment records of 35 patients were reviewed who were treated with composite resection alone, composite resection plus radiotherapy, or composite resection as a salvage procedure for a primary treatment failure. Combined irradiation and composite resection resulted in a higher local control than patients receiving composite resection alone (72% vs. 43%). There was no difference in complication rates between these two treatment groups. Composite resection as a salvage procedure resulted in local control in 38% of patients through this was associated with a 64% rate of complications. This data and a review of the literature suggest that tumors of the oral cavity and oropharynx with extension to the mandible requiring composite resection probably represent a category of tumors with a high risk of local recurrence and may benefit from adjuvant irradiation.

Aged↗
PubMed1988

An enhancer factor defect in a mutant Burkitt lymphoma cell line.

RJ 2.2.5 is an immunoselected mutant of the Burkitt lymphoma line Raji. It fails to display MHC class II antigens at the cell surface due to a transcriptional defect. We have identified the function of a regulatory factor that is defective in RJ 2.2.5 cells; this factor is absolutely required for the activity of an MHC class II gene enhancer.

DNA-Binding Proteins↗
PubMed1988

The enhancer in an MHC class II gene, in vitro and in mouso.

The E alpha class II gene of the major histocompatibility complex is expressed in a variety of immunocompetent cells. Part of the control of tissue-specific expression is mediated by a block of sequences found far upstream of the transcriptional startsite; this stretch is necessary for expression in the B lymphocytes of transgenic mice, but largely dispensable elsewhere. We review the evidence for the role of this region in E alpha transcription in transgenic animals, as well as data from transfections into tissue-culture cells, which indicate that this region has non-specific enhancer activity. We discuss possible models to explain how a non-specific enhancer can participate in cell-specific control.

Animals↗
PubMed1988

Ischemia-induced alterations of mitochondrial structure and function in brain, liver, and heart muscle of young and senescent rats.

Young and senescent rats (3 and 28-30 months old) were subjected to complete ischemia at 37 degrees C in order to study function and structure of mitochondria isolated from liver, heart muscle, and brain. The rates of energy-coupled respiration and ATP synthesis were found to decrease progressively in relation to time of ischemia. The respiratory rates in the absence of ADP (state 4 respiration) did not increase after exposure to ischemia, suggesting that ischemia primarily affects electron transport rather than the energy coupling system. Mitochondria of heart muscle were more affected by ischemia than mitochondria of brain and liver. Liver and heart muscle mitochondria obtained from young rats were found to be slightly more sensitive to short periods of ischemia than those isolated from senescent animals.

Adenosine Triphosphate↗
PubMed1988

B-cell control region at the 5' end of a major histocompatibility complex class II gene: sequences and factors.

Transcription of major histocompatibility complex class II genes is elaborately regulated. Mouse class II genes are transcribed primarily in B cells, peripheral macrophages and interdigitating cells, and thymic cortical and medullary cells. In this study, we began to identify the DNA sequences and protein factors that control expression of a class II gene in B cells, addressing in particular how closely they resemble those that regulate immunoglobulin gene expression. We describe a region upstream of the E alpha gene that is crucial for its transcription in the B cells of transgenic mice but is less important in cultured B-cell lines. The sequence of this region reveals several familiar motifs, including a second X-Y pair reminiscent of that residing in the promoter-proximal region of all class II genes, a B motif strikingly homologous to that associated with the immunoglobulin kappa gene enhancer, several Ephrussi motifs, and a Pu box-like sequence very similar to that implicated in simian virus 40 and lymphotrophic papovavirus expression in B cells. Careful study of the proteins that bind specifically to these different motifs prompts us to suggest that major histocompatibility complex class II and immunoglobulin genes rely on quite different factors to achieve B-cell-specific expression.

Animals↗
PubMed1987

Faecal alpha-1-antitrypsin and excretion of 111indium granulocytes in assessment of disease activity in chronic inflammatory bowel diseases.

Intestinal protein loss in chronic inflammatory bowel diseases may be easily determined by measurement of alpha-1-antitrypsin (alpha 1-AT) stool concentration and alpha 1-AT clearance. Both parameters were significantly raised in 36 and 34 patients respectively with chronic inflammatory bowel diseases, compared with eight patients with non-inflammatory bowel diseases, or 19 healthy volunteers. There was wide range of overlap between active and inactive inflammatory disease. Contrary to serum alpha 1-AT, faecal excretion and clearance of alpha 1-AT did not correlate with ESR, serum-albumin, orosomucoid, and two indices of disease activity. A comparison of alpha 1-AT faecal excretion and clearance with the faecal excretion of 111In labelled granulocytes in 27 patients with chronic inflammatory bowel diseases, showed no correlation between the intestinal protein loss and this highly specific marker of intestinal inflammation. Enteric protein loss expressed by faecal excretion and clearance of alpha 1-AT does not depend on mucosal inflammation only, but may be influenced by other factors.

Adolescent↗
PubMed1987

Leucocyte elastase in chronic inflammatory bowel diseases: a marker of inflammatory activity?

Leucocyte elastase is a neutral proteinase which plays an important role in the pathogenesis of inflammatory disorders. Infiltration of bowel mucosa by neutrophil and eosinophilic granulocytes is a characteristic feature of chronic inflammatory bowel diseases. We studied plasma elastase in 44 patients suffering from Crohn's disease or ulcerative colitis. Plasma levels were significantly higher in these patients compared to 7 patients with non-inflammatory bowel diseases or 53 healthy controls. Elevated plasma levels were more often found in patients with active inflammation than in those with inactive disease. Elastase did neither correlate with leucocyte counts, serum albumin, ESR, alpha 1-proteinase inhibitor and orosomucoid nor with clinical indices or the faecal excretion of 111In-labelled granulocytes. In serial studies of 15 patients, elastase did not always run parallel to the disease activity. We conclude that plasma elastase does not reliably indicate the inflammatory activity in chronic inflammatory bowel diseases.

Adult↗
PubMed1987

Providing free samples of baby items to newly delivered parents. An unintentional endorsement?

Recent studies have suggested that providing free sample packs of baby items to newly delivered parents may adversely influence parental health behavior. To determine the extent of this practice in Virginia, the head nurses of all 68 newborn nurseries and a random sample of 200 pediatricians were surveyed. Formula samples were being distributed at all hospitals. Formula packs were given to breast-feeding mothers at 65 (95%) hospitals although only 66 percent of the surveyed pediatricians approved of this practice. Samples of baby items other than formula (e.g., baby powder) were being distributed at 66 (97%) hospitals. Some physicians (18%) objected to the distribution of these nonformula samples, and others were not familiar with the content of these packs. In most instances, the hospital medical staff had not voted to approve the distribution of these packs. Parents were being informed only rarely about the source and intent of the packs. The provision of sample packs to newly delivered parents affects approximately 3,000,000 babies each year in the United States. The short- and long-term effects of providing these packs have been inadequately explored. Physicians should make an active decision whether to distribute sample packs. Those physicians choosing to dispense these samples may wish to review and edit the content of the packs and to enclose in the pack a brief note explaining that the provision of the products does not constitute a medical endorsement.

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