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Biomedical subjects

M Bach

Publications and source records attributed to M Bach.

At least 145 records · Page 8Linked to original sources
PubMed1989

Conservation between yeast and man of a protein associated with U5 small nuclear ribonucleoprotein.

The process of nuclear pre-messenger RNA splicing is similar in Saccharomyces cerevisiae and metazoan cells in that the two-step mechanism is identical and the reaction occurs in a large ribonucleoprotein complex, the spliceosome. Little is known, however, about the degree of conservation of splicing factors other than of the small nuclear RNAs (snRNAs). Yeast counterparts of the metazoan spliceosomal snRNAs (U1, U2, U4, U5 and U6) have been identified but, with the exception of U6, the yeast snRNAs are larger and sequence similarity is limited to short regions. By using antibodies against the yeast PRP8 protein, a pre-mRNA splicing factor of relative molecular mass 280,000 (Mr280K) stably associated with U5 small nuclear ribonucleoproteins (snRNPs), we have now identified an immunologically related protein in HeLa cell nuclear extracts. The HeLa cell protein has an Mr greater than 200K and is associated with purified 20S U5 snRNPs. This is the first report of phylogenetic conservation between yeast and man of a protein splicing factor.

Autoantibodies↗
PubMed1989

[Drug therapy of delusional parasitosis. The importance of differential diagnosis for psychopharmacologic treatment of patients with delusional parasitosis].

In 34 patients suffering from delusional parasitosis the relevance of an accurate differential diagnosis with respect to pharmacological treatment was investigated. Under a psychopharmacological therapy of the delusion's additional psychiatric symptomatology in 17 patients (50%) a full remission and in other 5 patients an improvement of the delusional symptoms was observed. The unexpected high recovery-rate is explained by the fact that all of the patients with additional depression showed a reduction also of the delusional symptomatology after a treatment with antidepressants. In contrast to that, patients with organic brain syndromes underlying the delusions had a significant worse outcome, which seems to be caused by the considerable lack of effective psychopharmacological treatment of such states. The results indicate that an accurate psychiatric differential diagnosis is of great importance for the psychopharmacological therapy of patients suffering from delusional parasitosis. In this context the Viennese decision-tree for delusional syndromes is discussed.

Adult↗
PubMed1989

Purification of the major UsnRNPs from broad bean nuclear extracts and characterization of their protein constituents.

Small nuclear ribonucleoprotein particles containing the five major nucleoplasmic snRNAs U1, U2, U4, U5 and U6 as well as two smaller sized snRNAs were purified from broad bean nuclear extracts by anti-m3G, monoclonal antibody, immunoaffinity chromatography. We have so far defined 13 polypeptides of approximate mol. wts. of 11 kd, 11.5 kd, 12.5 kd, 16 kd, 17 kd, 17.5 kd, 18.5 kd, 25 kd (double band), 30 kd, 31 kd, 35 kd, 36 kd and 54 kd. Upon fractionation of the UsnRNPs by anion exchange chromatography, essentially pure U5 snRNPs were obtained, containing the 11 kd, 11.5 kd, 12.5 kd, 16 kd, 17 kd, 17.5 kd, 35 kd and 36 kd polypeptides. These may therefore represent the common snRNP polypeptides and which may also be present in the other snRNPs. By immunoblotting studies, using anti-Sm sera and mouse monoclonal antibodies we show that the 35 kd and 36 kd proteins are immunologically related to the mammalian common B/B' proteins. The broad bean 16 kd and 17 kd proteins appear to share structural elements with the mammalian D protein. The three proteins of mol. wts. 11 kd, 11.5 kd and 12.5 kd probably represent the broad bean polypeptides E, F, and G. Cross-reactivity of proteins of mol. wts of 30 kd and 31 kd with Anti-(U1/U2)RNP antibodies suggests that they may represent the broad bean A and B" polypeptides. The 54 kd protein and the 18.5 kd protein could be candidates for the U1 specific 70 k and C polypeptides. Our results demonstrate a strong similarity between the overall structure of broad bean and mammalian snRNPs.

Chromatography, Affinity↗
PubMed1989

Evidence from complementation assays in vitro that U5 snRNP is required for both steps of mRNA splicing.

We have established an in vitro complementation system that has allowed us to investigate the role of individual purified snRNPs in the splicing of pre-mRNA molecules. For the preparation of snRNP-depleted nuclear extracts we have first removed the majority of endogenous snRNPs from the nuclear extracts by one passage over an anti-m3G column and then degraded the remaining snRNPs with micrococcal nuclease. The mixture of snRNPs U1, U2, U4/U6 and U5, obtained by anti-m3G immuno-affinity chromatography, was functionally active and able to restore the splicing of snRNP-depleted nuclear extracts. Mono-Q chromatography was used for further fractionation of the snRNPs U1-U6. This produced three fractions that were highly enriched in snRNPs U1 and U2, U5 and U4/U6 respectively. Conditions were found where addition of the [U1, U2] and the U4/U6 snRNP fractions to the snRNP-depleted nuclear extracts gave rise to the formation of splice intermediates in the absence of any 3' cleavage/exon 1-exon 2 product formation. Only when purified 20S U5 snRNPs were added did both steps of the splicing reaction occur efficiently. Our data suggest that U5 snRNP is absolutely required for the second step of splicing and is needed further for efficient initiation of the splicing reaction. The requirement for U5 snRNPs for splicing was corroborated by glycerol gradient sedimentation analysis of the respective reconstituted pre-mRNP complexes. Stable and efficient formation of 50-60S spliceosomes was observed only in the presence of all snRNPs.

Centrifugation, Density Gradient↗
PubMed1989

Pattern electroretinogram in glaucoma and ocular hypertension.

We recorded the pattern electroretinogram (PERG) to small (0.8 degree) and very large (15 degrees) check sizes in normal subjects, in patients with early-stage glaucoma, and in patients with ocular hypertension. In glaucoma, the PERG amplitude was reduced. This reduction was more prominent for a check size of 0.8 degree as compared with 15 degrees stimuli and for high (16/s) as compared with low (7.8/s) reversal rates. Using a discriminant analysis of the amplitudes for two different check sizes, we could distinguish the normal and the glaucoma groups with a specificity of 96% and a sensitivity of 91%. Of the ocular hypertension patients, 43% were classified as pathologic by the discriminant analysis. Thus multivariate analysis of the PERG may increase its diagnostic value.

Adult↗
PubMed1989

20S small nuclear ribonucleoprotein U5 shows a surprisingly complex protein composition.

U5 small nuclear ribonucleoprotein (snRNP), purified from HeLa nuclear extracts (splicing extracts), shows a complex protein composition. In addition to the snRNP proteins B', B, D, D', E, F, and G, which are present in each of the major snRNPs U1, U2, U4/U6, and U5, U5 snRNP contains a number of unique proteins characterized by apparent molecular masses of 40, 52, 100, 102, 116, and 200 (mostly a double band) kDa. The latter set of proteins may be regarded as U5-specific for the following reasons. They are not only eluted specifically, together with snRNP particles, from anti-2,2,7-trimethylguanosine immunoaffinity columns by 7-methylguanosine, they also cofractionate with U5 snRNP during chromatography and, most importantly, in glycerol gradient centrifugation. These U5 snRNP particles show a high sedimentation constant of about 20S. U5 snRNPs that lack the U5-specific proteins are also found in nuclear extracts but have (in comparison) a lower sedimentation value of only 8-10S. Autoimmune sera from patients with systemic lupus erythematosus were identified that, on immunoblots with purified U5 snRNP proteins, reacted selectively with the 100- or 200-kDa proteins. This indicates that at least the high molecular mass U5-specific proteins are structurally distinct and not derived one from the other by proteolytic degradation. The existence of so many unique proteins in the U5 snRNP suggests that this snRNP particle may exert its function during splicing mainly by virtue of its protein components.

Antigen-Antibody Complex↗
PubMed1989

SS-B (La) nuclear antigen: fast and non-degradative procedure to prepare SS-B extracts free from other nuclear antigens.

A procedure is described allowing the easy and fast obtention of a cellular extract from calf thymus, enriched in the undegraded 52 kDa SS-B protein. As seen by western blot, the extract does not contain Sm and RNP antigens, allowing the use of such fraction for the detection of anti-SS-B antibodies without the interference of the anti-Sm and anti-RNP specificities. The enrichment avoids denaturing agents, making the fraction suitable for use in functional and structural studies.

Animals↗
PubMed1989

[Predominance of crossed optic nerve fibers is a characteristic of albinism, but not of dissociated vertical deviation].

We examined eight patients with dissociated vertical deviation (DVD) for evidence of misrouting in the visual pathway, using visually evoked potentials. Full-field monocular pattern-onset chequerboard stimulation was employed. The visually evoked potentials were recorded from both occipital lobes. Their differential activity during stimulation of the right eye was compared with that obtained during stimulation of the left eye. In contrast to an earlier report, a predominance of the crossed projection was not found in any of the DVD cases. The results in eight normal control subjects were similar, unlike our findings in eight albino patients (predominance of crossed projection: a relative positivity over the contralateral hemisphere about 100 ms after pattern-onset). Possible artifacts are discussed that may have led to the earlier assumption of misrouting in DVD patients.

Adolescent↗
PubMed1988

Check-size specific changes of pattern electroretinogram in patients with early open-angle glaucoma.

The pattern electroretinogram was recorded in patients with initial stages of visual field defects due to open-angle glaucoma and in age-matched normal subjects. Both normal subjects and glaucoma patients had a visual acuity above 0.8. Counterphasing checkerboard patterns were used as visual stimuli with a range of check sizes from 0.8 degree to 15 degrees at 7.8 reversals/s. Whereas the amplitude in glaucoma patients was nearly normal for large check sizes, it was significantly reduced for small check sizes (p = 0.003). Possibly two separate mechanisms that generate the pattern electroretinogram for small and large checks are differentially affected; they may be related to the magnocellular and parvocellular systems. The difference between normals and glaucoma patients was even more significant when the ratios of the amplitudes at small and large check sizes were compared (p less than 0.0002). When this ratios is used, the amplitude variability can be partly overcome and the pattern electroretinogram can be a sensitive indicator of ganglion cell function.

Aged↗
PubMed1987

SS-B (La) nuclear antigen. Organization in structural domains of the protein moiety.

Stable degradation products, obtained by digestion with endogenous and V8 proteases of calf thymus SS-B (La) antigenic protein, have been studied. The most characteristic fragments have molecular masses of 47, 30, 23 and 17 kDa. The 47-kDa and 30-kDa fragments are complex and are constituted of a number of species of different isoelectric points, as has been described for the SS-B protein molecule from other sources. Degradation products from the entire SS-B nuclear antigen still contain the 30-kDa SS-B fragment, suggesting that the 30-kDa region of the SS-B protein molecule is firmly attached to the RNA moiety. A model is presented that implies the presence of two hinge regions sensitive to proteases and three structural domains that correspond to segments of 30 kDa, 17 kDa and 5-6 kDa.

Amino Acid Sequence↗
PubMed1987

ELISA for determination of albumin in the nanogram range: assay in cerebrospinal fluid and comparison with radial immunodiffusion.

An ELISA double antibody sandwich technique on polystyrene microtiter plates for quantitation of albumin in cerebrospinal fluid is described. Commercially available reagents are used for this assay, in which albumin in the range between 0.1-1 ng/100 microliters can easily be detected. Albumin determinations in 30 CSF samples by this method revealed concentrations of 0.1-0.8 mg/ml. Results obtained by ELISA correlated significantly with those from parallel experiments with commercially available RID assays. The ELISA described is a sensitive, simple, and expeditious assay for determination of albumin in the nanogram range and may be a promising method for routine analysis of albumin concentrations in CSF.

Albumins↗
PubMed1987

Pattern electroretinogram plus visual evoked potential: a decisive test in patients suspected of malingering.

Along the processing chain in the visual pathway the pattern electroretinogram (PERG) is a better indicator of the peripheral function than the visual evoked potential (VEP). Therefore the PERG and the VEP will be impaired equally by disturbances before the ganglion cell layer (e.g., blurred image or retinal disease) and differently by further centrally located diseases (e.g., tumor compression of the optic nerve). Thus in patients complaining of reduced visual acuity who show disturbed VEP but a normal PERG, malingering can be definitely ruled out. Representative combinations of PERG and VEP findings are described.

Adult↗
PubMed1987

C-wave versus electrooculogram in diseases of the retinal pigment epithelium.

The c-wave and the electrooculogram (EOG) are retinal potentials predominantly generated by the pigment epithelium. In most diseases both parameters show a parallel decrease in amplitude. However, in patients with dominant drusen, and cone dystrophies, and in clinically nonaffected members of families suffering from vitelliform macula degeneration, the EOG is close to normal whereas the c-wave shows a reduced amplitude. These findings suggest a higher sensitivity of the generators of the c-wave compared with those responsible for the EOG. Thus the direct current electroretinogram provides additional diagnostic information.

Electrooculography↗