MR of childhood-onset dentatorubral-pallidoluysian atrophy

MR findings in a 14-year-old boy with progressive myoclonic epilepsy, who was diagnosed as having dentatorubral-pallidoluysian atrophy by DNA analysis, were compared with those of his father, who had adult-onset dentatorubral-pallidoluysian atrophy. Besides showing severe brain atrophy, especially of the brain stem tegmentum and cerebellum, MR showed diffuse periventricular hyperintensity on T2-weighted images. As compared with the proband, the father had a mild case.     

Huntington's disease and dentatorubral-pallidoluysian atrophy: proteins, pathogenesis and pathology

Each of the glutamine repeat neurodegenerative diseases has a particular pattern of pathology largely restricted to the CNS. However, there is considerable overlap among the regions affected, suggesting that the diseases share pathogenic mechanisms, presumably involving the glutamine repeats. We focus on Huntington's disease (HD) and Dentatorubral-pallidoluysian atrophy (DRPLA) as models for this family of diseases, since they have striking similarities and also notable differences in their clinical features and pathology. We review the pattern of pathology in adult and juvenile onset cases. Despite selective pathology, the disease genes and their protein products (huntingtin and atrophin-1) are widely expressed. This presents a central problem for all the glutamine repeat diseases-how do widely expressed gene products give rise to restricted pathology? The pathogenic effects are believed to occur via a "gain of function" mechanism at the protein level. Mechanisms of cell death may include excitotoxicity, metabolic toxicity, apoptosis, and free radical stress. Emerging data indicate that huntingtin and atrophin-1 may have distinct protein interactions. The specific interaction partners may help explain the selective pathology of these diseases.     

Clinical analysis of human urinary proteins using high resolution electrophoretic methods

The application of isoelectric focusing (IEF), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional electrophoresis (2-DE) and capillary electrophoresis (CE) for high resolution electrophoretic analysis of human urinary proteins is reviewed. In each case, the information is tabulated chronologically with details of sample preparation, electrophoretic system, detection method and clinical application. The text includes an historical perspective of the use of each method for urinalysis and a detailed review of the application of the methods to the investigation of renal disease, renal transplantation, Bence Jones proteinuria (BJP), diabetes mellitus, cadmium toxicity, nephrolithiasis and cancers of the urogenital tract.     

The brainstem and thalamic lesions in dentatorubral-pallidoluysian atrophy: an MRI study

We studied the frequency and characteristics of brainstem and thalamic lesions in dentatorubral-pallidoluysian atrophy using MRI. Of 15 subjects diagnosed by DNA analysis, 13 had lesions in the pontine base, nine in the midbrain, and five in the thalamus. Lesions were correlated positively with the patient's age, but not with neurologic features or numbers of CAG repeats. Patients with Machado-Joseph disease or spinocerebellar ataxia 1 did not show these characteristic lesions.     

A novel method for quantitative analysis of recombinant secreted proteins using two-dimensional electrophoresis

We describe a two-dimensional polyacrylamide gel electrophoresis (2-D PAGE)-based approach for detecting and quantifying secreted recombinant proteins in media conditioned by baby hamster kidney (BHK) cells. Seven secreted proteins were analyzed in this system: leptin, thrombopoietin, thrombin, glycoprotein 130, soluble interleukin-2 receptor, and two novel sequences obtained from sequence database searches. BHK cells transfected with plasmids encoding each of these proteins, and cells transfected with empty plasmids (control cells), were metabolically labeled and the resulting conditioned media were analyzed by 2-D PAGE. Gel images derived from cells expressing recombinant proteins were compared with images from control cells in order to identify spots corresponding to the expressed proteins. All seven of the test proteins were successfully detected using this method. The sensitivity of the system was evaluated by diluting samples derived from high-expressing clones with conditioned media from control cells. The sensitivity of detection was protein-dependent, but recombinant proteins expressed at levels as low as 10 ng/mL could be detected. Quantification of recombinant protein levels was achieved by measuring spot intensities using phosphorimager analysis. The intensity of spots corresponding to recombinant proteins were compared with the spot intensity of an endogenous BHK protein which had been calibrated to a known standard. Estimates of the levels of expressed protein determined using this technique correlated with the levels determined using standard affinity assays. We conclude that this system provides a reliable method for quantifying levels of protein expression when specific assays are unavailable.     

Synthesis and two-dimensional electrophoretic analysis of mixed populations of circular and linear RNAs

Spontaneous cleavage of the less abundant form of tobacco ringspot virus satellite RNA is readily reversible. Capitalizing on earlier observations by Feldstein and Bruening that small 'mini-monomer' RNAs derived from this molecule and containing little more than covalently attached ribozyme and substrate cleavage products are able to efficiently circularize, we have constructed a series of self-circularizing RNAs of precisely known size. Mixtures of linear and circular RNAs synthesized in vitro and containing 225-1132 nt could be completely resolved using a novel two-dimensional denaturing polyacrylamide gel electrophoresis system. Similar analyses of a complex mixture of coconut cadang-cadang viroid RNAs revealed the presence of relatively large amounts of a previously undescribed 'fast-slow' heterodimeric RNA species in infected palms. Only a single DNA template is required to prepare each pair of circular and linear RNA markers.     

A sporadic case of dentatorubral-pallidoluysian atrophy (DRPLA) having an elderly age of onset

We reported a sporadic case of DRPLA that had an elderly age of onset. The patient was a 71-year-old woman. Her parents, sisters and a brother didn't have neurologic diseases. She had been well until the age of 68 years, when she noticed her unstable gait. On neurologic examination cerebellar ataxia and a tremor at the neck were noticed, but we were unable to differentiate her disease from the other types of spinocerebellar degeneration. An MRI of the cranium showed atrophy of the cerebellum, pons, brain stem and cerebrum, and a diffuse lesion of the cerebral white matter. These findings made us suspect her disease of DRPLA. When we analyzed the CAG repeat in the DRPLA gene, we found it expanded to 57. We thought that the elderly onset related to a relatively mild expansion.     

Characterization of the major proteins of bovine seminal fluid by two-dimensional polyacrylamide gel electrophoresis

Recently, we demonstrated that the major proteins from bovine seminal plasma BSP-A1, -A2, -A3 and -30-kDa (collectively called BSP proteins) specifically interact with choline phospholipids. These proteins coat the surface of the spermatozoa after ejaculation and are believed to play an important role in membrane modifications occurring during capacitation. In this study we determined the isoelectric point (pl) and analysed the molecular heterogeneity of BSP proteins. Total protein from bovine seminal plasma (CBSP) and purified BSP proteins were iodinated using chloramine T. Samples were reduced, denatured, separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and visualized by autoradiography. Analysis of CBSP proteins demonstrated the presence of polypeptides migrating in the pH range of 3.5-7.8 and at molecular weights (M(r)) between 6 and 100 kDa. isoforms of each BSP protein were found when purified iodinated proteins were analysed by 2D-PAGE. BSP-A1 was found at a M(r) of 16.5 kDa and in the range of pl of 4.7-5.0; BSP-A2 at 16 kDa and at a pl of 4.9-5.2; BSP-A3 at 15 kDa and at a pl of 4.8-5.2, and BSP-30-kDa at 28 kDa and at a pl of 3.9-4.6. Similar results were obtained with immunolocalization of BSP proteins after Western blot using specific antibodies. The treatment of purified iodinated BSP proteins with neuraminidase increased the pl of BSP-30-kDa to 4.8-5.0 and decreased its M(r) to 25 kDa, but no change was observed for BSP-A1, -A2 and -A3. The treatment of BSP proteins with sulfatase or acid phosphatase modified neither their M(r) nor their pl. Furthermore, when CBSP proteins were separated in 2D-PAGE and the gels stained for glycoproteins with dansyl hydrazine, BSP proteins were among the major glycoproteins found in the bovine seminal plasma. In conclusion, BSP proteins are acidic and have several isoforms. Furthermore, the heterogeneity of BSP-30-kDa is mainly due to its sialic acid content.     

Characterization of Bangor virus proteins by using monoclonal antibodies

A new virus was isolated from a finch in quarantine in Northern Ireland in 1973. The virus had the morphological characteristics of a paramyxovirus, and was named Bangor virus (BaV). In order to identify the structural proteins of BaV and to investigate the biological characterization of the virus, 28 monoclonal antibodies (mAbs) directed against BaV were prepared. Eight of these mAbs reacted with the nucleocapsid protein (NP), 10 with hemagglutinin-neuraminidase (HN) protein, and 10 with fusion (F) protein. With the aid of these mAbs, the structural proteins of BaV were determined, namely, p52, gp74, gp63, and gp51 were identified as the NP, HN, F0, and F1 proteins, respectively. The biological activities of the mAbs directed against the envelope glycoproteins of BaV were examined. Intriguingly, it was found in the neutralization assay that four mAbs directed against the HN protein of BaV can enhance the fusion of HeLa cells infected with BaV, showing the presence of a potential third function of the HN protein that affects the fusion activity of the F protein. Furthermore, all of the anti-F protein mAbs showed neutralizing activity.     

Two-dimensional electrophoretic analysis of human milk-fat-globule membrane proteins with attention to apolipoprotein E patterns

Two-dimensional (2-D; Iso Dalt method) electrophoresis was done on lipid membrane fractions from human milk samples collected in polypropylene tubes at home by the mother. The samples represent milk from two weeks to ten months post partum. Identification was made by immunoassay of Western blots. Apolipoprotein E was not easily seen on silver-stained gels because concentration is small and spots overlap another protein. Blot assays show a more complex pattern than 34 kDa plasma apo E with molecular size isoforms at 36 kDa, 34 kDa, 20 kDa and 15 kDa. One sample was negative for apo E. Apo E plays an important role in lipid transport in tissue and in the brain. It is synthesized in a variety of tissues by specific cells. Milk may reflect several sources.     

Glutathione S-transferases: two-dimensional electrophoretic protein markers of lead exposure

Glutathione S-transferases (GST) are a family of detoxification isoenzymes that catalyze the conjugation of xenobiotics and their metabolites with reduced glutathione. Lead exposure in rats is known to induce GST isoenzymes in the liver and kidney. These changes in expression have potential use as biomarkers of lead exposure. Because two-dimensional electrophoresis (2-DE) enables one to analyze both protein abundance changes and chemical changes in protein structure, 2-DE was used to determine the effect of in vivo lead exposure on GST isoform expression in rat kidney cytosols. Male Sprague-Dawley rats were exposed to inorganic lead, and proteins were separated by conventional ISO-DALT and NEPHGE-DALT techniques and blotted for immunological identification. Lead exposure caused detectable inductions in both GSTP1 and GSTM1 and quantifiable charge modification in GSTP1. These preliminary data confirm the utility of 2-D electrophoretic GST analysis as indicative of lead exposure and toxicity and support its use for further elaboration of lead's effects on renal protein expression.     

Extraction of membrane proteins by differential solubilization for separation using two-dimensional gel electrophoresis

We describe the extraction and enrichment of membrane proteins for separation by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) after differential solubilization of an Escherichia coli cell lysate. In a simple three-step sequential solubilization protocol applicable for whole cell lysates, membrane proteins are partitioned from other cellular proteins by their insolubility in solutions conventionally used for isoelectric focusing (IEF). As the first step, Tris-base was used to solubilize many cytosolic proteins. The resultant pellet was then subjected to conventional solubilizing solutions (urea, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, dithiothreitol, Tris, carrier ampholytes). Following the completion of this step, 89% of the initial E. coli sample mass was solubilized. Finally, the membrane protein rich pellet was partially solubilized using a combination of urea, thiourea, tributyl phosphine and multiple zwitterionic surfactants. Using N-terminal sequence tagging and peptide mass fingerprinting we have identified 11 membrane proteins from this pellet. Two of these outer membrane proteins (Omp), OmpW and OmpX, have previously been known only as an open reading frame in E. coli, while OmpC, OmpT and OmpTOLC have not previously been identified on a 2-D gel. The prefractionation of an entire cell lysate into multiple fractions, based on solubility, results in simplified protein patterns following 2-D PAGE using broad-range pH 3.5-10 immobilized pH gradients (IPGs). Additional advantages of sample prefractionation are that protein identification and gel matching, for database construction, is a more manageable task, the procedure requires no specialized apparatus, and the sequential extraction is conducted in a single centrifuge tube, minimizing protein loss.     

Genomic organization analysis of acidophilic chemolithotrophic bacteria using pulsed field gel electrophoretic techniques

The genomic organization of acidophilic chemolithotrophic bacteria belonging to the genus Thiobacillus, Thiomonas and Leptospirillum was studied using pulsed field gel electrophoresis techniques (PFGE). The electrophoretic analysis of intact DNA prepared from different strains showed that all have a circular chromosome, with sizes ranging from 1.9 Mb for Leptospirillum ferrooxidans ATCC 49879, the smallest genome for an acidophilic strict chemolithoautotrophic microorganism, to 3.8 Mb for Thiomonas cuprina DSM 5495, the largest in this study. The number of extrachromosomal elements present varied from none, as observed in several isolates of Leptospirillum ferrooxidan, to five in Thiobacillus thiooxidans ATCC 8085. The mixotroph Thiomonas cuprina DSM 5495 was found to have a linear 50 kb megaplasmid which was inducible when the bacteria was grown in chemolithotrophic conditions. Low-frequency restriction fragment analysis (LFRFA) of different acidophilic chemolithotrophs and related species was carried out by PFGE to determine macrorestriction patterns for rare cutters (SpeI, XbaI, SwaI, PmeI), which were then used for taxonomic identification (karyotyping), genome size determination, and generation of physical and genetic maps.     

Two replica blotting methods for fast immunological analysis of common proteins in two-dimensional electrophoresis

Knowledge of the photon spectrum of a radiotherapy beam is often needed for three-dimensional (3-D) dose calculations using Monte Carlo methods and/or algorithms employing energy deposition kernels. Direct measurement of the x-ray energy fluence spectrum is not feasible for the high-energy photon beams used clinically. In this paper, the spectrum is extracted from basic beam data that are readily obtained for a clinical beam. We describe the photon spectrum using just two parameters. One parameter, which determines the high-energy part of the spectrum, is obtained using the measured dose in the buildup region for a small field, where electron contamination of the beam can be neglected. The other parameter is extracted from the photon beam attenuation in water. The results compare favorably to spectra generated from Monte Carlo simulations.     

Preparative two-dimensional gel electrophoresis of membrane proteins

Electrophoretic techniques, and especially two-dimensional gel electrophoresis (2-DE), have provided an indispensable set of tools for the separation of complex protein mixtures as well as for the identification of protein-protein interactions. Nevertheless, after its introduction more than twenty years ago and even with recent technical developments, the separation of integral and peripheral membrane proteins, in amounts sufficient for microsequencing, is still a difficult task. Lipids present in the membrane as well as the low solubility of hydrophobic membrane proteins result in protein aggregation both on the sample application point and on isoelectric focusing. As a consequence many proteins do not enter the first or second dimension of 2-DE. Here we describe the modification of a protocol using a combination of 3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate (CHAPS), chaotropic agents (thiourea, urea), Tris base and reducing agents (1,4-dithioerythritol) to improve solubilization of integral and peripheral membrane proteins. Preparative amounts of membrane proteins (up to 2 mg) were loaded during reswelling of dry immobilized pH gradients and the resulting Coomassie staining patterns were largely superimposable with silver-stained gels obtained from identical samples (4 microg). This indicates that the recovery of proteins from the sample is not significantly compromised by the scale-up procedure. A direct application of this method for the characterization and identification of membrane proteins from cellular organelles is described in another paper in this issue (I. Fialka et al., Electrophoresis 1997, 18, 2582-2590).     

Capillary electrophoretic analysis of synthetic short-chain oligoribonucleotides

Thirty synthetic oligoribonucleotides, 3 to 18 nucleotides (nt) long, were analyzed by capillary electrophoresis, under nondenaturing conditions, using a commercial kit. The migration time t(m) was dependent on nt length and composition, capillary length, operating temperature, and type of sieving polymer. Under fixed experimental conditions, the t(m) proved predictable by the equation: t(m) = [0.22(n-1) + 6.14A/n + 6.86G/n + 3.61 (C+U)/n] min, for n>3, where A/n, G/n, C/n, U/n is the frequency of each type of nt within the oligonucleotide (ONT). The equation accounts for the influence of charge-to-mass ratio on t(m), but not for structural effects, if present. This approximation is acceptable for short ONTs. The possibility of detecting n+1, n-1, n-2 impurities, having predicted the t(m), is of crucial importance in assessing the purity of synthetic ONTs dedicated to structural studies. This appears to be feasible. High resolution was shown among homologous series of ONTs of increasing length, and in some cases, even within groups of ONTs of the same length but different composition. The addition of 7 M urea to the buffer, as denaturing agent, accelerates the t(m) and significantly lowers the resolution for the shortest ONTs. It was also possible to monitor the state of association of mixtures of RNA and DNA sequence-complementary strands.     

Characterization of a composite gradient gel for the electrophoretic separation of lipoproteins

We describe a protocol for making a new type of gradient gel, the Composite gradient gel, that was designed to resolve plasma lipoproteins using nondenaturing gradient gel electrophoresis. The new gel format allows analysis both of high density lipoproteins (HDLs) and low density lipoproteins (LDLs) on the same gel. The gel gave highly repeatable (r2 = 0.999) size estimates. We compared lipoprotein phenotypes determined from the new gradient gel with those obtained using specialized HDL and LDL gradient gels. The comparisons indicated that the Composite gel gave lipoprotein particle size estimates for HDLs and LDLs that were virtually identical to those obtained, respectively, from the specialized HDL and LDL gradient gels. We measured median diameters, which reflect the distributions of absorbance, for LDLs and for HDLs and found that the Composite gel gave lipoprotein size distributions that were virtually identical to those measured using the specialized LDL and HDL gels. Finally, comparison of fractional absorbance for six lipoprotein size intervals obtained from the Composite and specialized gels revealed a close correlation (r2 = 0.828). Thus, it appears that both LDL and HDL size phenotypes may be evaluated simultaneously using a single gradient gel format.     

The use of electrophoretic methods for determining modified proteins in diabetic patients

Modified proteins were determined by isoelectric focusing in borate-polyol system with subsequent colorimetry (micromethod) and electrophoresis of blood serum on paper with subsequent TCA-ethanol treatment. Increased levels of glycated hemoglobin and modified albumin and changed light absorbance of glycated albumin were detected. The levels of glycated hemoglobin assessed by the micromethod and colorimetry without calibration did not correlate.     

Characterization of viral double-stranded RNA-binding proteins

Previous studies in a weanling rat model indicated that dietary calcium depletion not only stimulated osteoclastic resorption but also inhibited bone formation. The present study sought to test whether the depletion-associated inhibition of bone formation is related to a reduction in serum insulin-like growth factor-I (IGF-I) and/or an increase in its binding proteins (IGFBPs). Twenty male weanling rats were divided into two weight-matched groups. The study group was subjected to a semisynthetic diet deficient in calcium (0.02% calcium) for 28 days, while the control group was pair-weighed on the same diet but containing 0.62% calcium. After the depletion phase, all rats were fed the same calcium-containing diet for an additional 14 days. Serum samples were obtained from each animal on a weekly basis and assayed for IGF-I and IGFBPs. During depletion, there was no statistically significant difference in serum IGF-I level between the study group and the control group. In contrast, the study group showed a statistically significant increase in several serum IGFBPs with apparent molecular size of 30-38 kD (IGFBP-3), 26-28 kD (IGFBP-1, -2, -5, and/or -6), and 24-25 kD (IGFBP-4), respectively, compared to the control group. There was no difference in nutritional intakes between the two groups of rats during depletion. During repletion, there was also no significant difference in serum IGF-I level between the control and study group. However, during the first 7 days of repletion, serum IGFBP-3 and the 26-28 kD IGFBP of the study group was significantly less than those of the control group, which then returned to the control level after 2 weeks of repletion. In summary: (1) calcium depletion in weanling rats increased several serum IGFBPs without an effect on IGF-I; and (2) calcium repletion induced an acute reduction in serum IGFBP-3. In conclusion, these findings represent the first evidence that the depletion-related inhibition of bone formation in the rat may be associated with an increase in several serum IGFBPs, which may act to inhibit the osteogenic actions of IGFs.     

Mutational analysis of the hMLH1 gene using an automated two-dimensional DNA typing system

Directiveness and nondirectiveness are considered here as psychological phenomena and separated from the issue of giving or withholding advice. The former is a form of persuasive communication involving various combinations of deception, coercion, and threat, whereas the latter describes procedures that promote and enhance the autonomy and self-directedness of clients. Examples are given showing that professionals have considerable difficulty dealing with relatively simple, common issues arising in genetic counseling. It is suggested that many, if not most, problems involving the issue of nondirectiveness arise because of inadequacies in applying basic counseling skills. Several examples are given of nondirective counseling in situations involving direct questions and the proffering of "advice." The need to raise standards in counseling training is underscored if the field of genetic counseling is to remain nondirective.