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Biomedical subjects

J Becker

Publications and source records attributed to J Becker.

At least 37 records · Page 2Linked to original sources
PubMed1998

False-positive LSD testing in urine samples from intensive care patients.

Unexpected positive results for lysergic acid diethylamide (LSD) were found in urine samples from 12 patients in an intensive care unit in a routine screening using the CEDIA DAU assay. None of these test results could be confirmed by high-performance liquid chromatography analysis, but all samples contained the mucolytic drug ambroxol. Further studies demonstrated that ambroxol exhibits a significant cross-reactivity in the CEDIA DAU LSD assay. Therefore, positive LSD results obtained with the CEDIA DAU assay have to be critically evaluated, particularly during the cold season, when infections of the respiratory tract often result in more frequent use of mucolytic medications.

Adult↗
PubMed1998

Assessment of conjunctival epithelium after severe burns and surgical reconstruction with Tenon plasty by means of a modified impression cytology procedure.

PURPOSE: Tenon plasty has been used to reconstruct the conjunctival surface in severe burns in which ischemic sclera was exposed or undergoing ulceration. A modified impression cytology procedure was applied to investigate the conjunctival epithelium. The quality of the regenerated epithelium on the advanced Tenon sheets was assessed. METHODS: The 63 conjunctival samples of eye-burn patients were investigated. Among these, 41 patients had very severe bums. Conjunctival samples were collected from 6 weeks after surgery to 5 years after the accident. They were compared with conjunctival epithelia obtained from 53 normal eyes of healthy volunteers. A 25-mm2 Biopore membrane (Millipore Catalogue PICM 01250) was placed on the bulbar conjunctiva surface in the lower temporal quadrant, at a distance of 3-5 mm from the limbus, till it was soaked with fluid. The ablated cell sheets were stained with periodic acid-Schiff (PAS). RESULTS: In all cases, an intact conjunctival epithelium was observed. In healthy eyes, 2,338 epithelial cells/mm2 and 155 goblet cells/ mm2 were found. Eyes after a surgical reconstruction with Tenon plasty resulted only in 1,575 epithelial cells/mm2 and 72 goblet cells/mm2. The differences were highly significant. The ratio of epithelial to goblet cell counts revealed an increase of goblet cells during the postoperative period. CONCLUSION: Conjunctival epithelium as well as goblet cell densities were reduced after heat, lime, alkali, and acid burns. However, after concrete burns, cell densities were increased. Tenon plasty provided the regeneration of the fully intact conjunctival epithelium. Goblet cells were present from 6 weeks after the surgery on; their number increased gradually. The stimulation of the goblet cell mucous secretion is discussed.

Adult↗
PubMed1998

Dependency and self-criticism in bipolar and unipolar depressed women.

OBJECTIVES: The dependency and self-criticism scores of women with histories of either unipolar disorder (N = 74) or bipolar disorder (N = 20) or no psychiatric history (N = 24) were compared to determine the influence of state depression on these personality dimensions. DESIGN: All women completed the Depressive Experiences Questionnaire and the Beck Depression Inventory. Patients were divided into currently depressed and remitted groups. RESULTS: Currently depressed women with unipolar disorder were more self-critical and dependent than non-psychiatric controls; women with unipolar disorder whose depression remitted were more self-critical only. Women in both the depressed and remitted bipolar groups were more self-critical than controls. Depressed bipolar patients did not differ from the controls in their level of dependency; remitted bipolar patients were significantly less dependent than controls. CONCLUSIONS: Dependency needs in depressed women are heavily influenced by mood state. Self-criticism appears to be a-characterological trait in both major depression and bipolar disorder. Women with bipolar disorder in remission report fewer dependency needs than women with no history of psychiatric disorder. The data provide partial support for Blatt's (1974) hypothesis that dependency and self-criticism reflect relatively stable personality dimensions in patients with a mood disorder.

Adult↗
PubMed1998

The osteogenic potential of free periosteal autografts in tibial fractures with severe soft tissue damage: an experimental study.

The present study was undertaken on 80 adult male New Zealand rabbits to assess the effect of free nonvascularized, autologous, periosteum transplants on bone healing in a rabbit fracture model comparable to a tibial fracture with severe soft tissue damage. Comparison was made between transplantation of free autologous periosteal grafts on the anteromedial side of the tibia and nontransplantation on the contralateral tibia (control). We produced a standardized transverse osteotomy of both tibial diaphyses. The medullary cavity was reamed and nailed ; a 1-cm segment of periosteum was excised from either side of the osteotomy. Periosteal and extraosseous ingrowth was prevented at the osteotomy site by a silastic sheet wrapped around two-thirds of the circumference of the tibia. On the silastic-free bone window, in one group we spanned the osteotomy with a free nonvascularized longitudinally-oriented autologous periosteum sewn to the adjacent periosteum proximally and distally. In the second group, the periosteum was placed transversely with a gap between it and the adjacent periosteum proximally and distally. Revascularization of the graft was determined with the colored microsphere technique. Our data suggest that orthotopically-placed autologous nonvascularized periosteum retains its osteogenic potential in a poorly vascularized environment comparable to a tibial fracture with severe soft tissue damage ; the effect is enhanced if the graft is in contact with intact periosteum. Histologically, callus formation after periosteal grafting resembles endochondral and intramembranous ossification.

Animals↗
PubMed1997

Discrimination of amino acids mediating Ras binding from noninteracting residues affecting raf activation by double mutant analysis.

The contribution of residues outside the Ras binding domain of Raf (RafRBD) to Ras-Raf interaction and Ras-dependent Raf activation has remained unresolved. Here, we utilize a double mutant approach to identify complementary interacting amino acids that are involved in Ras-Raf interaction and activation. Biochemical analysis demonstrates that Raf-Arg59 and Raf-Arg67 from RafRBD are interacting residues complementary to Ras-Glu37 located in the Ras effector region. Raf-Arg59 and Raf-Arg67 also mediate interaction with Ras-Glu37 in Ras-dependent Raf activation. The characteristics observed here can be used as criteria for a role of residues from other regions of Raf in Ras-Raf interaction and activation. We developed a quantitative two-hybrid system as a tool to investigate the effect of point mutations on protein-protein interactions that elude biochemical analysis of bacterially expressed proteins. This assay shows that Raf-Ser257 in the RafCR2 domain does not contribute to Ras-Raf interaction and that the Raf-S257L mutation does not restore Raf binding to Ras-E37G. Yet, Raf-S257L displays high constitutive kinase activity and further activation by Ras-G12V/E37G is still impaired as compared with activation by Ras-G12V. This strongly suggests that the RafCR2 domain is an independent domain involved in the control of Raf activity and a common mechanism for constitutively activating mutants may be the interference with the inactive ground state of the kinase.

Amino Acid Substitution↗
PubMed1997

The acidic C-terminal domain of rna1p is required for the binding of Ran.GTP and for RanGAP activity.

The small GTP binding protein Ran is an essential component of the nuclear protein import machinery whose GTPase cycle is regulated by the nuclear guanosine nucleotide exchange factor RCC1 and by the cytosolic GTPase activating protein RanGAP. In the yeasts Schizosaccharomyces pombe and Saccharomyces cerevisiae the RanGAP activity is encoded by the RNA1 genes which are essential for cell viability and nucleocytoplasmic transport in vivo. Although of limited sequence identity the two yeast proteins show a conserved structural organization characterized by an N-terminal domain of eight leucine-rich repeats, motifs implicated in protein-protein interactions, and a C-terminal domain rich in acidic amino acid residues. By analyzing the RanGAP activity of a series of recombinantly expressed rna1p mutant derivatives, we show that the highly acidic sequence in the C-terminal domain of both yeast proteins is indispensable for activating Ran-mediated GTP hydrolysis. Chemical cross-linking reveals that the same sequence in rna1p is required for rna1p.Ran complex formation indicating that the loss of GAP activity in the C-terminally truncated rna1p mutants results from an impaired interaction with Ran. The predominant species stabilized through the covalent cross-link is a rna1p.Ran heterodimer whose formation requires the GTP-bound conformation of Ran. As the acidic C-terminal domain of rna1p is required for establishing the interaction with Ran, the leucine-rich repeats domain in rna1p is potentially available for additional protein interactions perhaps required for directing a fraction of rna1p to the nuclear pore.

Amino Acid Sequence↗
PubMed1997

A Drosophila muscle-specific gene related to the mouse quaking locus.

We have characterized a novel muscle-specific gene of Drosophila melanogaster, defined by enhancer trap strain 24B of Brand and Perrimon (1993). We show that transcripts of the gene accumulate within presumptive mesoderm and persist within developing muscles, strongly suggesting that the encoded protein is involved in muscle cell determination and differentiation. cDNA sequences reveal that the Drosophila protein is similar to quaking (64% identity over 210 amino acids), a protein essential for mouse embryogenesis, and gld-1 (53% identity over 162 amino acids) a germ-line-specific tumor suppressing protein of the nematode, Caenorhabditis elegans. We demonstrate that the Drosophila gene resides within the 93F chromosome subdivision, and describe its physical map. Finally, we have used the gene, which we have named quaking-related 93F (qkr93F), to identify a family of closely related KH domains.

Amino Acid Sequence↗
PubMed1997

Enhanced apoptotic cell death of renal epithelial cells in mice lacking transcription factor AP-2beta.

Expression of AP-2 transcription factors has been detected previously in embryonic renal tissues. We show here that AP-2beta -/- mice complete embryonic development and die at postnatal days 1 and 2 because of polycystic kidney disease. Analyses of kidney development revealed that induction of epithelial conversion, mesenchyme condensation, and further glomerular and tubular differentiation occur normally in AP-2beta-deficient mice. At the end of embryonic development expression of bcl-X(L), bcl-w, and bcl-2 is down-regulated in parallel to massive apoptotic death of collecting duct and distal tubular epithelia. Addressing the molecular mechanism we show that transfection of AP-2 into cell lines in vitro strongly suppresses c-myc-induced apoptosis pointing to a function of AP-2 in programming cell survival during embryogenesis. The position of the human AP-2beta gene was identified at chromosome 6p12-p21.1, within a region that has been mapped for autosomal recessive polycystic kidney disease (ARPKD). Sequence analyses of ARPKD patients and linkage analyses using intragenic polymorphic markers indicate that the AP-2beta gene is located in close proximity to but distinct from the ARPKD gene.

Animals↗
PubMed1997

An integrated genetic and physical map of the autosomal recessive polycystic kidney disease region.

Autosomal recessive polycystic kidney disease is one of the most common hereditary renal cystic diseases in children. Genetic studies have recently assigned the only known locus for this disorder, PKHD1, to chromosome 6p21-p12. We have generated a YAC contig that spans approximately 5 cM of this region, defined by the markers D6S1253-D6S295, and have mapped 43 sequence-tagged sites (STS) within this interval. This set includes 20 novel STSs, which define 12 unique positions in the region, and three ESTs. A minimal set of two YACs spans the segment D6S465-D6S466, which contains PKHD1, and estimates of their sizes based on information in public databases suggest that the size of the critical region is < 3.1 Mb. Twenty-eight STSs map to this interval, giving an average STS density of < 1/150 kb. These resources will be useful for establishing a complete transcription map of the PKHD1 region.

Base Sequence↗
PubMed1997

PET brain mapping study of auditory verbal supraspan memory versus visual fixation in schizophrenia.

Changes in regional cerebral blood flow (rCBF), associated with performance of an auditory verbal supraspan memory task, were studied in eight remitted DSM-III-R schizophrenic patients and eight pair-wise matched normal controls. Four positron emission tomography (PET) scans, using the [15O]-H2O technique, were acquired: two while subjects fixated a cross hair and two while performing a verbal free-recall supraspan memory task. Task performance showed typical patterns of recency and primacy effects in both groups; however, patients performed more poorly than controls on the primary (working) memory aspect of the task. Regions showing rCBF changes overlapped in both groups and were similar to those seen in previous studies of normals; however, patients had smaller increases in rCBF than controls in frontal and superior temporal cortical regions bilaterally. Our results suggest that remitted patients with schizophrenia demonstrate impairments of capacity-limited information processing, which may be related to metabolic dysfunction within a distributed network of brain structures, including the prefrontal and temporal cortical regions; however, dysfunction limited to the frontal cortex cannot be ruled out by the results of this experiment.

Adult↗
PubMed1997

Model for the examination of evolutionary trends in tooth development.

Through the use of serial computerized tomography (C-t) scans, two distinct developmental stages can be identified in mature teeth. C-t scans thus provide a non-destructive method for assessing growth within individual teeth, as well as for comparison of the development of modern and fossil teeth. The second deciduous molar (DM2) and first permanent molar (M1) resemble one another morphologically, despite differences in size and developmental rates. Thus, they provide an excellent model for studying variation in growth within an individual. To test the C-t method, we first examined a recent archaeological sample and then examined teeth from Skhul I. Serial C-t scans were used to compare two distinct developmental stages represented by the dentine-enamel junction (DEJ) and outer enamel surface (OES), respectively, in mandibular DM2 and M1 of 31 archaeological specimens. The difference in form and size between these two surfaces in and between teeth was calculated from intercusp distances measured at the DEJ and OES using the form distance matrix. Intercusp distances at the DEJ and OES of these teeth were then compared to their counterparts in the DM2 and M1 of Skhul I, taken here as representative of early anatomically modern Homo sapiens sapiens. Form differences between paired DM2 and M1 at the DEJ were smaller than those at the OES, supporting the hypothesis that differences between the two teeth increase throughout development. The increase in intercusp distances from the DEJ to OES was found to reflect the angulation of cusps relative to one another, rather than enamel thickness. Form differences between the Skhul DM2 and M1 were smaller than those observed in the recent series, and the recent M1 differed more than the DM2 from its fossil counterpart. The similarities found between the Skhul permanent and deciduous teeth and the recent DM2, may reflect a similar growth pattern. This would contribute to earlier crown completion in the fossil M1.

Animals↗
PubMed1997

Green fluorescent protein/beta-galactosidase double reporters for visualizing Drosophila gene expression patterns.

We characterized 120 novel yeast Ga14-targeted enhancer trap lines in Drosophila using upstream activating sequence (UAS) reporter plasmids incorporating newly constructed fusions of Aequorea victoria green fluorescent protein (GFP) and Escherichia coli beta-galactosidase genes. Direct comparisons of GFP epifluorescence and beta-galactosidase staining revealed that both proteins function comparably to their unconjugated counterparts within a wide variety of Drosophila tissues. Generally, both reporters accumulated in similar patterns within individual lines, but in some tissues, e.g., brain, GFP staining was more reliable than that of beta-galactosidase, whereas in other tissues, most notably tests and ovaries, the converse was true. In cases of weak enhancers, we occasionally could detect beta-galactosidase staining in the absence of discernible GFP fluorescence. This shortcoming of GFP can, in most cases, be alleviated by using the more efficient S65T GFP derivative. The GFP/beta-gal reporter fusion protein facilitated monitoring several aspects of protein accumulation. In particular, the ability to visualize GFP fluorescence enhances recognition of global static and dynamic patterns in live animals, whereas beta-galactosidase histochemistry affords sensitive high resolution protein localization. We present a catalog of Ga 14-expressing strains that will be useful for investigating several aspects of Drosophila melanogaster cell and developmental biology.

Animals↗
PubMed1997

[Bart syndrome--separate entity or a variant of epidermolysis bullosa?].

Bart syndrome was described first by Bart in 1966; it represents the combination of congenital epidermolysis bullosa, congenital localized absence of skin affecting the extremities and shedding or dystrophy of nails. This syndrome may be of clinical relevance because of its more favourable prognosis in comparison with other forms of epidermolysis bullosa. We report two patients with Bart syndrome and focus on the question, if this syndrome represents a distinct entity or a variant of epidermolysis bullosa.

Consanguinity↗