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Biomedical subjects

J Becker

Publications and source records attributed to J Becker.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1995

Barley microsatellites: allele variation and mapping.

Microsatellites have developed into a powerful tool for mapping mammalian genomes and first reports about their use in plants have been published. A database search of 228 barley sequences from GenBank and EMBL was made to determine which simple sequence repeat (SSR) motif prevails in barley. Nearly all types of SSRs were found. The (A)n and (T)n SSRs occurred more often than (C)n and (G)n for n > or = 10. Among the dinucleotide repeats, the (CG)n SSRs occurred least often. Trinucleotide repeats did not occur with n > 7 and there is no correlation between the GC content in the trinucleotide motifs and the number of observed SSRs. Analysing 15 different microsatellites with 11 barleys yielded 2.1 alleles per microsatellite. Sequencing 25 putative microsatellites showed that the resolution capacity of high-quality agarose gels was sufficient to determine differences of only three base pairs. Five microsatellites were mapped on three different chromosomes of a barley RFLP map.

Alleles↗
PubMed1995

Explorative study of interleukin levels in the human cornea.

BACKGROUND: The presence of interleukins has been demonstrated in the cornea and other ocular tissues. Although pathogenic mechanisms are unknown, interleukins seem to be involved in inflammatory disorders of the cornea. The present study was undertaken to analyse concentrations of interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6) in human corneas with various clinical diagnoses. METHODS: Immediately after keratoplasty 127 explanted human corneas with various corneal diseases were snap frozen and cryosections were prepared for histological examination. Furthermore, the protein content was measured according to the method of Bradford and the concentration of IL-1 beta and IL-6 were determined using a specific immunosorbent test (ELISA). RESULTS: It was found that IL-1 beta and IL-6 level were clearly higher in corneas with ulcerations and distinct inflammatory signs. Lower levels of both interleukins were found in corneas with a weak expression of inflammatory signs. CONCLUSIONS: Keratitis, keratoconus with inflammatory signs, and ulcerating processes showed higher interleukin levels than corneas with non-inflammatory disorders like scar formation, corneal dystrophy and keratoconus. The results could show that, depending on the clinical diagnosis, the inflammatory status of the cornea may be evaluated by the interleukin levels determined in the corneal tissue.

Cornea↗
PubMed1995

Ultrastructural alterations and environmental exposure influence the opiate concentrations in hair of drug addicts.

Hair samples were taken at autopsy from the head of 1 male and 1 female subject both known as drug abusers. Some of the strands were bleached by in-vitro cosmetic treatment. The bleached hair as well as the original hair samples were partly exposed to water or soil prior to further investigations and drug monitoring. The exposure times were 4 weeks or 6 months for water and 6 months for soil. The hair fibers were examined by transmission electron microscope (TEM) and by scanning electron microscope (SEM) investigations. The electron microscope studies confirmed that all experimental conditions had produced morphological alterations in the hair fibers. After exposure to water or to soil for 6 months as well as after storage of the clipped bleached hair in tap water at room temperature for 4 weeks, drug monitoring of formerly positive hair samples gave negative results. After storage of natural hair in soil or in water for 4 weeks the opiate levels had dramatically decreased. The samples were screened by fluorescence polarization immunoassay after enzymatic digestion. The results were confirmed by GC/MS.

Environmental Exposure↗
PubMed1995

Longitudinal quantitative EEG study of children with different performances on a reading-writing test.

In a previous paper, using the same test for the evaluation of reading-writing abilities, Harmony et al. (1990b) reported that children with severe difficulties had more delta in fronto-temporal regions, and this was interpreted as a sign of underlying cerebral dysfunction. Children with severe and minor difficulties in the test had more diffuse theta absolute and relative powers and less alpha relative power. As theta decreases with age, while alpha increases, these results suggested that children with minor and severe difficulties in reading had a maturational lag with respect to those with normal performance. We conducted this study in order to test this hypothesis. Two different EEG records were obtained with an interval of 2.58-3.15 years in 49 children classified in 3 groups according to their performance in a reading-writing test. Group 1: adequate performance for age and degree (control group); group 2: below level performance with minor difficulties; and group 3: below level performance, with severe difficulties. The mean age of the groups in the first study was 9 years. Absolute (AP) and relative powers (RP) in the delta, theta, alpha and beta bands were computed for each session. In general, groups 3 and 2 showed greater changes than group 1 from session to session. ANOVAs performed by session clearly demonstrate many significant differences between groups in the first study, while few significant differences in parieto-occipital regions in theta RP were observed in the second session. These results point toward a maturational spurt of children from groups 2 and 3.

Brain↗
PubMed1995

Electroencephalographic coherences discriminate between children with different pedagogical evaluation.

The relationship of reading-writing ability and EEG coherences was studied in 84 subjects from two age groups 7.0-8.9 and 9-11.2 years old. All children were divided into three groups according to their performance on a pedagogical test: ped1, normal children; ped2, children with mild problems; ped3, children with reading-writing disability. The following results were obtained: in general, children showed higher coherences in groups with poor performance in the delta, theta and beta bands. In the alpha band, higher coherence values were related to better performance. The exceptions to this general pattern were rare. Group ped2 had higher coherences in delta, theta and alpha bands than ped1 and ped3, in left temporal leads. In older children the same tendency was observed, but group differences in the theta, alpha and beta bands were few. In this age range, the significant group differences were almost all interhemispheric coherences. The discriminant analysis that classified subjects by their coherence values gave very good results, fact that demonstrates, that EEG coherence is a highly sensitive measurement indicating not only the existence of a reading-writing problem, but also the degree of its severity.

Age Factors↗
PubMed1995

Cloning, sequencing, and characterizing the Lactobacillus leichmannii pyrC gene encoding dihydroorotase.

The gene encoding dihydroorotase (DHOase) of Lactobacillus leichmannii, the third enzyme of the pyrimidine biosynthetic pathway (Genbank (EMBL) accession no X78999), was cloned by phenotypic complementation of an E coli pyrC deficient mutant after transformation with Lactobacillus leichmannii genomic library DNA. The open reading frame of the L leichmannii pyrC gene spans 1281 bp and codes for a 427 amino cid polypeptide with a calculated M(r) of 46,316 Da. Primer extension showed that the initiation site for transcription is 37 bp upstream of the putative start codon ATG and Northern blot analysis confirmed its independent transcription from the adjacent pyrB gene. Comparison of the deduced amino acid sequence of L leichmannii DHOase with sequences established for other organisms yielded 46.6% identity with the corresponding Bacillus subtilis enzyme. Highly conserved protein domains suggest importance for the enzyme's function.

Amino Acid Sequence↗
PubMed1995

Psychiatric disorders in spouse caregivers of care recipients with Alzheimer's disease and matched controls: a diathesis-stress model of psychopathology.

To test a diathesis-stress model of psychopathology, the authors examined the rates of current and lifetime psychiatric disorders in 82 spouse caregivers of Alzheimer's disease (AD) patients and 86 demographically matched controls. Caregivers and controls did not differ in the prevalence of disorders before the onset of care recipients' AD (or during a similar time period for the controls); caregivers experienced more depressive-anxiety disorders after the onset of patient's AD than controls. This study strongly supported the 3 key components of a diathesis-stress interaction. First, caregivers with a psychiatric history prior to the onset of patient's AD were more likely than caregivers with no history to receive a diagnosis after the onset of AD. Second, a similar relationship existed for controls. Finally, caregivers with a psychiatric history were more likely to experience a recurrence after the onset of AD than controls with a psychiatric history. These findings indicate that the diathesis of psychiatric history and the stress of caregiving interact, resulting in the observed group differences in the prevalence of psychiatric disorders.

Aged↗
PubMed1995

Altered expression of extracellular matrix proteins and integrins in oral lichen planus (OLP).

The immunohistochemical distribution of collagens type I, III, IV, V, VI, of undulin and tenascin, and of integrins alpha 2, alpha 3, alpha 4, alpha 5, alpha 6 and beta 4, was studied in 14 biopsies of oral lichen planus (OLP), 5 biopsies of orthokeratinized gingiva and 4 biopsies of oral fibrous hyperplasia. The localization of extracellular matrix proteins showed altered expression in OLP when compared to normal oral mucosa, with two principal patterns corresponding to the reticular or atrophic type. Whereas in the reticular type a focal loss of immunoreactivity for collagen types I, III, V, VI and undulin was noted in areas with a cellular infiltrate, in the atrophic variant almost complete loss of immunoreactivity of the subepithelial extracellular matrix was found. There was no clear correlation between the distribution of extracellular matrix proteins and their integrin receptors. The present findings suggest that the autoimmune reaction in OLP might not be primarily targeted to oral keratinocytes but to an unknown antigen in the connective tissue stroma. The changes in the subepithelial extracellular matrix associated with the inflammatory reaction might, especially in the atrophic variant, impair the cross-talk between epithelium and mesenchyme and favour both the loss of barrier function and the development of erosions in the clinical course of the disease.

Adult↗
PubMed1995

Mapping of digested and undigested random amplified microsatellite polymorphisms in barley.

The broad use of microsatellites as a tool for constructing linkage maps in plants has been limited by the need for sequence data to detect the underlying simple sequence repeats. Therefore, random amplified microsatellite polymorphisms (RAMPs) were studied as an alternative approach for barely mapping. Labelled (GA)n simple sequence repeat primers were combined with RAPD primers of different length and sequence to generate RAMPs. To get additional polymorphisms (called dRAMPs), the obtained products were also analysed after digestion with MseI. There were 0-11 polymorphisms found per primer combination. Sixty RAMPs/dRAMPs identifying 40 new loci were mapped onto a barley RFLP map. The new DNA markers are found on all chromosomes and they increased the length of the barely map by 174 cM to a total of 1270 cM. Interestingly, the RAMPs/dRAMPs caused stretching effects in genome areas where stretching was also observed for AFLPs.

Base Sequence↗
PubMed1995

[Ethanol ingestion following Antabus overdose: acetaldehyde-induced cardiological emergency].

The differential diagnosis of chest pain is challenging, when the clinical presentation appears pathognomonic, yet conventional diagnostic tests fail to reveal the suspected cause. We report the case of a 38-year-old patient who had an acetaldehyde intoxication (antabuse syndrome) in the setting of disulfiram overdose and ethanol ingestion. The patient presented with severe angina pectoris. Coronary artery disease was suspected, because the patient had risk factors and electrocardiographic repolarization changes were present. During the further investigation it became evident that symptoms were solely caused by acetaldehyde intoxication following disulfiram and alcohol ingestion. Toxic levels of acetaldehyde were found in the patient's serum. Coronary artery disease was ruled out by cardiac catheterization.

Acetaldehyde↗
PubMed1995

[Hepatitis C virus: results of detection in several high risk groups in the X region of Chile].

The aim of this study was to determine the prevalence of hepatitis C virus antibodies in high risk patients coming from Valdivia, Osorno and Puerto Montt. Fifty-six patients in hemodialysis, 51 renal graft recipients, 42 cirrhotics and 14 patients with acute non A non B hepatitis were studied. Antibodies were detected with a second generation ELISA technique and positive cases were confirmed with RIBA. All hemodialysis patients and renal graft recipients were negative for hepatitis C virus antibodies. In one non alcoholic patient with cirrhosis, a positive ELISA was confirmed with RIBA. Six patients with acute hepatitis had positive ELISA tests but none was confirmed with RIBA. It is concluded that the prevalence of hepatitis C virus antibodies in this region of Chile is very low.

Acute Disease↗
PubMed1995

Remarks on the vitality of the human cornea after organ culture.

The purpose of this study was to obtain further information on the viability of organ-cultured human cornea. We thus used a specific staining method for succinate dehydrogenase (SDH), which is located in the membrane system of vital mitochondria. We examined fresh and long-term-cultured human corneas. After an initial incubation period in dextran-free culture medium, corneas were stored in a medium containing dextran. With respect to different appearances of the SDH staining, minimal essential medium without dextran seems to have a positive effect on the condition of epithelial cells. After renewal of the medium, keratocytes showed a brief improvement followed by a delayed deterioration, while the endothelial cells were severely damaged. However, best results for all three cell types were observed on the fourth day in a medium containing dextran. We therefore conclude that these corneas were best suited for transplantation.

Adolescent↗