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Biomedical subjects

J Becker

Publications and source records attributed to J Becker.

At least 109 records · Page 6Linked to original sources
PubMed1997

Tarsoconjunctival advancement: a modified surgical technique to correct cicatricial entropion and metaplasia of the marginal tarsus.

Severe eye burns and mucocutaneous cicatricial disorders frequently cause upper and lower lid entropion with metaplasia of the tarsal conjunctiva, dislocation of the meibomian gland orifices, trichiasis, and tarsal scars near the lid margin. Between 1985 and 1993, 26 patients (29 eyes, 36 lids) were treated by excision of pathologic tissue and advancement of the tarsoconjunctival layer. The presented procedure is used mainly in cicatricial entropion with keratinization of the marginal tarsus.

Cicatrix, Hypertrophic↗
PubMed1996

Collagen VI regulates normal and transformed mesenchymal cell proliferation in vitro.

Suggestions exist that, in addition to traditional growth factors, the extracellular matrix (ECM) of a cell can regulate its proliferation. This hypothesis was investigated with normal and transformed fibroblasts because they exhibit specific intracellular responses after adherence to ECM and produce large quantities of ECM proteins. Although cells cultured on different ECM proteins grew more rapidly than those on plastic, adherence and cell growth on an individual ECM protein were not correlated. To test if ECM can stimulate cell growth, soluble ECM proteins were given to cells after plating. In this culture system only collagen VI (CVI), at a concentration of 20 microg/ml in medium, increased 3T3 cell number to 402% of control by 72 h. Similar increases of human fibroblasts and HT 1080 cell numbers were noted. DNA synthesis of all three cell types increased 24 h after addition of soluble CVI. A mixture of CVI single chains, yielded by reduction and alkylation, was not stimulatory. However, this mixture efficiently inhibited the DNA synthesis induced by native CVI. Antibody inhibition studies showed that the region of CVI stimulating proliferation differs from the site bound by the integrin receptor alpha2beta1, which mediates cell adhesion to immobilized CVI. Heparin inhibited a portion of CVI-induced proliferation. These data demonstrate that CVI can stimulate mesenchymal cell growth via a pathway that is independent of the integrin alpha2beta1 and that the stimulatory region appears to be within the native helical portion of the collagen.

3T3 Cells↗
PubMed1996

Cognitive therapy versus fluoxetine in the treatment of dysthymic disorder.

We studied the effects of a fixed dose of fluoxetine (20 mg) or cognitive psychotherapy in a 16 week trial of patients with dysthymic disorder. More patients assigned to fluoxetine dropped out of the 16 week treatment (33%) than those assigned to cognitive therapy (9%), but this difference did not attain statistical significance. Both treatments showed improvement over baseline conditions at 8 weeks and further improvement at 16 weeks. There were no statistically significant group differences in treatment response. No follow-up data were collected so the enduring effects of the treatments are unknown. An optimal treatment for dysthymic disorder may be combined psychotherapy and pharmacotherapy for a longer period of time.

Adolescent↗
PubMed1996

Fatal cerebellar haemorrhage due to phenprocoumon poisoning.

A 32-year-old patient died of a cerebellar haemorrhage and the blood coagulation analysis before death suggested defective synthesis of vitamin K-dependent clotting factors due to vitamin K deficiency. The post-mortem toxicological examination of different tissues revealed phenprocoumon poisoning as the cause of death. The differential diagnosis of vitamin K deficiency and the toxicology of hydroxycoumarins are discussed.

Adult↗
PubMed1996

Molecular characterization of the xerC gene of Lactobacillus leichmannii encoding a site-specific recombinase and two adjacent heat shock genes.

Sequencing of four overlapping DNA fragments comprising 3.527 kb isolated from a L. leichmannii genomic library revealed three complete open reading frames (ORFs) and one that was truncated. The deduced amino acid sequences of the complete ORFs showed considerable similarities with the already known sequences of the xerC, hslV, and hslU gene products of Escherichia coli: the site-specific XerC recombinase, a member of the lambda integrase family, and the HtpI resp. HtpO heat shock proteins. The deduced amino acid sequence of the fourth, incomplete ORF upstream the xerC gene showed strong homology with the gid A gene product of B. subtilis.

Amino Acid Sequence↗
PubMed1996

Molecular cloning and characterization of the pyrB gene of Lactobacillus leichmannii encoding aspartate transcarbamylase.

The Lactobacillus leichmannii pyrB gene, encoding pyrimidine biosynthetic enzyme aspartate transcarbamylase (ATCase), was cloned from a partial genomic library lying on a 1468 bp Sa/I/BstXI fragment. The predicted polypeptide sequence extending over 351 amino acid residues (M(r) 39 855 Da) was compared to those of various other organisms revealing clear identities towards them and important conservative stretches, implying that these proteins are closely related. Transcriptional initiation was mapped by primer extension and occurred 54 bp upstream of the pyrB open reading frame (ORF). Northern blot analysis indicates that the pyrB gene is transcribed as a single mRNA and not together with the following overlapping pyrC gene as a bicistronic mRNA. At high copy number the pyrB gene of L leichmannii seems to be lethal for its E coli host; inserted in a low copy vector it complements the uracil auxotrophy of an E coli pyrB mutant which shows distinct ATCase activity in the cell extract. With an excess of uracil in the growth medium the gene is apparently repressed and no ATCase activity can be measured.

Amino Acid Sequence↗
PubMed1996

[Establishing human, conjunctival fibroblast cultures as a test system for evaluating ophthalmic drugs].

BACKGROUND: Chronic inflammation of the anterior eye segment caused by severe burns has to be treated by several drugs. Often it is very difficult to recognize the relationship between drug and side effects. Although the results were usually satisfying, proliferation of the conjunctival tissue was observed. Therefore the question was raised whether these proliferations might have been a side effect of the drugs. To answer this question, we established cultures of human conjunctival fibroblasts for ocular toxicity testing of drugs used in the therapy of severe eye burns. MATERIALS AND METHODS: Conjunctival fibroblasts from young donors were cultured under standard conditions (37 degrees C, 5% C02, 95% RH) in Medium 199 supplemented with 20% FCS without antibiotics. At the time of inoculation the following drugs were added: aprotinin, prednisolone, chloramphenicol and methylhydroxypropylcellulose. Cell growth was observed and growth kinetics were estimated by hemocytometer over a period of 7 days. RESULTS: The investigations of prednisolone showed the well-known dose-dependent anti-proliferative effect. The application of methylhydroxypropylcellulose resulted in decreased cell growth and in total cell detachment. Experiments with aprotinin and chloramphenicol showed no effects on the growth behaviour. The application of a drug mixture lead to similar results as in experiments with prednisolone. DISCUSSION: The presented cell-culture system is able to reproduce specific effects, especially the toxicity of ophthalmic drugs but a complex interaction of an inflammatory reaction, e.g. after severe eye burns, cannot be simulated. The network of reactions and the interaction of many substances playing an important role during this process are too complex.

Adult↗
PubMed1996

Functional interaction of cytosolic hsp70 and a DnaJ-related protein, Ydj1p, in protein translocation in vivo.

In order to analyze the in vivo role of the SSA class of cytosolic 70-kDa heat shock proteins (hsps) of Saccharomyces cerevisiae, we isolated a temperature-sensitive mutant of SSA1. The effect of a shift of mutant cells (ssa1ts ssa2 ssa3 ssa4) from the permissive temperature of 23 degrees C to the nonpermissive temperature of 37 degrees C on the processing of several precursor proteins translocated into the endoplasmic reticulum or mitochondria was assessed. Of three mitochondrial proteins tested, the processing of only one, the beta subunit of the F1F0 ATPase, was dramatically affected. Of six proteins destined for the endoplasmic reticulum, the translocation of only prepro-alpha-factor and proteinase A was inhibited. The processing of prepro-alpha-factor was inhibited within 2 min of the shift to 37 degrees C, suggesting a direct effect of the hsp70 defect on translocation. More than 50% of radiolabeled alpha-factor accumulated in the precursor form, with the remainder rapidly reaching the mature form. However, the translocation block was complete, as the precursor form could not be chased through the translocation pathway. Since DnaJ-related proteins are known to interact with hsp70s and strains containing conditional mutations in a dnaJ-related gene, YDJ1, are defective in translocation of prepro-alpha-factor, we looked for a genetic interaction between SSA genes and YDJ1 in vivo. We found that a deletion mutation of YDJ1 was synthetically lethal in a ssa1ts ssa2 ssa3 ssa4 background. In addition, a strain containing a single functional SSA gene, SSA1, and a deletion of YDJ1 accumulated the precursor form of alpha-factor. However, no genetic interaction was observed between a YDJ1 mutation and mutations in the SSB genes, which encode a second class of cytosolic hsp70 chaperones. These results are consistent with SSA proteins and Ydj1p acting together in the translocation process.

Adenosine Triphosphatases↗
PubMed1996

Rapid purification and characterization of two distinct N-deoxyribosyltransferases of Lactobacillus leichmannii.

Two distinct N-deoxyribosyltransferases of Lactobacillus leichmannii, designated as DRTase I and DRTase II, were separated and purified almost to homogeneity by one-step affinity chromatography. DRTase I is distinguished by specifically catalyzing the direct transfer of 2-deoxyribosyl residues from purine deoxyribonucleosides to free purine bases, whereas DRTase II has a rather broad substrate specificity and is able to transfer the deoxyribosyl moiety between pyrimidines and between purines and pyrimidines. Furthermore, in addition to the different substrate spectrum, we clearly differentiated the two enzymes by comparing their varying temperature/activity and pH/activity profiles, their kinetic constants, their behaviour in Western blot analysis, and their N-terminal amino acid sequences. Denaturing and non-denaturing DISK-PAGE revealed strong evidence that both intact enzymes consist of hexamers with subunit molecular weights of approximately 20,000 for DRTase I and 18,000 for DRTase II.

Adenine↗
PubMed1996

Characterization of the factor VIII defect in 147 patients with sporadic hemophilia A: family studies indicate a mutation type-dependent sex ratio of mutation frequencies.

The clinical manifestation of hemophilia A is caused by a wide range of different mutations. In this study the factor VIII genes of 147 severe hemophilia A patients--all exclusively from sporadic families--were screened for mutations by use of the complete panel of modern DNA techniques. The pathogenous defect could be characterized in 126 patients (85.7 percent). Fifty-five patients (37.4 percent) showed a F8A-gene inversion, 47 (32.0 percent) a point mutation, 14 (9.5 percent) a small deletion, 8 (5.4 percent) a large deletion, and 2 (1.4 percent) a small insertion. Further, four (2.7 percent) mutations were localized but could not be sequenced yet. No mutation could be identified in 17 patients (11.6 percent). Sixteen (10.9 percent) of the identified mutations occurred in the B domain. Four of these were located in an adenosine nucleotide stretch at codon 1192, indicating a mutation hotspot. Somatic mosaicisms were detected in 3 (3.9 percent) of 76 patients, mothers, comprising 3 of 16 de novo mutations in the patients mothers. Investigation of family relatives allowed detection of a de novo mutation in 16 of 76 two-generation and 28 of 34 three-generation families. On the basis of these data, the male:female ratio of mutation frequencies (k) was estimated as k = 3.6. By use of the quotients of mutation origin in maternal grandfather to patients mother or to maternal grandmother, k was directly estimated as k = 15 and k = 7.5, respectively. Considering each mutation type separately, we revealed a mutation type-specific sex ratio of mutation frequencies. Point mutations showed a 5-to-10-fold-higher and inversions a >10-fold-higher mutation rate in male germ cells, whereas deletions showed a >5-fold-higher mutation rate in female germ cells. Consequently, and in accordance with the data of other diseases like Duchenne muscular dystrophy, our results indicate that at least for X-chromosomal disorders the male:female mutation rate of a disease is determined by its proportion of the different mutation types.

Base Sequence↗
PubMed1996

Co-ordinating care for Canadian travellers.

Case management is a popular term these days. It refers to caring for the whole patient and his or her family by incorporating all necessary resources available within the community.

Canada↗
PubMed1995

Combined mapping of AFLP and RFLP markers in barley.

AFLP marker technology allows efficient DNA fingerprinting and the analysis of large numbers of polymorphic restriction fragments on polyacrylamide gels. Using the doubled haploids from the F1 of the cross Proctor x Nudinka, 118 AFLP markers were mapped onto a barley (Hordeum vulgare L.) RFLP map, also including five microsatellite and four protein marker loci. The AFLP markers mapped to all parts of the barley chromosomes and filled in the gaps on barley chromosomes 2L, 4L and 6 in which no RFLP loci had been mapped. Interestingly, the AFLP markers seldom interrupted RFLP clusters, but grouped next to them. The combined map covers 1873 cM, with a total of 282 markers. The merging of AFLP and RFLP markers increased the total map length; 402 cM were added to the map at the tips of chromosomes or in regions corresponding to earlier gaps. Another 375 cM resulted from mapping AFLP markers near to RFLP clusters or in between non-clustered RFLP markers.

Base Sequence↗
PubMed1995

RNA1 encodes a GTPase-activating protein specific for Gsp1p, the Ran/TC4 homologue of Saccharomyces cerevisiae.

Ran/TC4 is a ras-related GTP-binding protein predominantly located in the nucleus. Ran/TC4 is essential for nuclear transport and is involved in mitotic control. In Saccharomyces cerevisiae a gene highly homologous to Ran/TC4 has been identified and named GSP1. Like all ras-related GTP-binding proteins, Gsp1p undergoes cycles of GTP hydrolysis and GDP/GTP exchange. The switching between the two different nucleotide bound states regulates the function of these GTP-binding proteins. Here we identify the product of the yeast RNA1 gene as the GTPase-activating protein (GAP) of Gsp1p. RNA1 belongs to a group of genes which are conserved in a variety of different organisms. We have expressed and purified recombinant Gsp1p and Rna1p from Escherichia coli. The GTPase activity of Gsp1p is stimulated 10(7)-fold by Rna1p. In addition, we find that the previously identified human RanGAP1 and rna1p from Schizosaccharomyces pombe are also able to induce GTPase activity of Gsp1p. The GTP hydrolysis of Ran is induced by RanGAP1 and rna1p but not by Rna1p. Implications for the suggested functions of Ran/TC4/Gsp1p in nuclear transport and mitotic control are discussed.

Base Sequence↗
PubMed1995

Sequence analysis of a 5.6 kb fragment of chromosome II from Saccharomyces cerevisiae reveals two new open reading frames next to CDC28.

The sequence of a 5653 bp DNA fragment of the right arm of chromosome II of Saccharomyces cerevisiae contains two unknown open reading frames (YBR1212 and YBR1213) next to gene CDC28. Gene disruption reveals both putative genes as non-essential. ORF YBR1212 encodes a predicted protein with 71% similarity and 65% identity (total polypeptide of 376 aa) with the 378 aa Surl protein of S. cerevisiae, while the putative product of ORF YBR1213, which is strongly expressed, has 28% identity with a Lactococcus lactis-secreted 45 kDa protein and 24% identity with the Saccharomyces cerevisiae AGA1 gene product.

Amino Acid Sequence↗
PubMed1995

Alcohol and injury. A case-crossover study.

OBJECTIVE: To determine whether and to what extent alcohol consumption increases the risk of injury. DESIGN: The case-crossover study is a new research design for assessing rare acute events (such as trauma) in relation to intermittent exposures (such as alcohol use) that have transient effects. All interviewed patients serve as their own controls, and the study design compares exposure during a "case" period, such as the 6 hours prior to injury, with exposure during a "control" period, such as the same 6-hour window on the previous day. SETTING: Emergency centers of a university hospital and a private not-for-profit hospital in a small midwestern city. PATIENTS: Three hundred fifty adults who presented with an injury within 48 hours of the event. DATA COLLECTED: Retrospective self-report of alcohol use in each of the 28 days and each of the 30 hours prior to injury, demographic variables, drug use prior to injury, patients' attributions regarding causes of their injury, and weather factors. RESULTS: Primary analysis was based on pairs of observations that were discordant for alcohol use in the 6 hours prior to injury and the same 6-hour window on the previous day. The odds ratio for one or more standard drinks vs none was 2.5 (95% confidence interval, 1.2 to 5.4); for four or more drinks vs three or fewer, 5.0 (95% confidence interval, 1.4 to 27). CONCLUSION: Alcohol use in the 6 hours prior to injury is associated with an increased risk of injury. The findings are consistent with a dose-response effect, but with this sample size no threshold of risk was found.

Adult↗
PubMed1995

Developmental expression of connexins in the chick embryo myocardium and other tissues.

BACKGROUND: Connexins are cell surface proteins that form specialized regions of cell-cell communication called gap junctions. These allow impulse conduction in in voluntary muscle tissue such as the heart, but also allow the formation of communities of like cells during development of organs. METHODS: We used an antipeptide antibody to connexin 43 in immunolocalization studies and an anti-peptide antibody to an external loop domain common to most connexins in Western blotting of total heart protein to measure the accumulation of connexins in the heart as it develops from 33 hours to 21 days (hatching), and in the adult. RESULTS: Immunolocalization revealed that connexin 43 is widely distributed in the earliest organ rudiments. It is especially prominent in the neural tube and its derivatives, in the lens and nasal placodes, in the foregut and its derivatives, in the somites, in the mesonephric tubules, and in the heart and major arteries. Heart tissue staining grew more intense with development through day 8. However, at day 11 and day 15, and in the adult, heart staining diminished. Endocardium and valve tissue did not stain. Western blotting of heart homogenates with the antibody directed against the external loop domain peptide showed 26, 32, 43, 45, and 56 kilodalton connexins, which changed in relative abundance, displaying unique patterns during development. CONCLUSIONS: Our results show patterns of connexin immunolocalization in early germ layers and organ rudiments that are similar to those known in the mouse, but with certain differences. Our results show a distinctive pattern of multiple connexin gene expression in the developing heart from days 2-21.

Animals↗