PubMed Health⌕ Search

Biomedical subjects

R Brenner

Publications and source records attributed to R Brenner.

At least 37 records · Page 2Linked to original sources
PubMed2000

Complementation of physiological and behavioral defects by a slowpoke Ca(2+) -activated K(+) channel transgene.

The Drosophila slowpoke gene encodes a large conductance calcium-activated potassium channel used in neurons, muscle, and some epithelial cells. Tissue-specific transcriptional promoters and alternative mRNA splicing generate a large array of transcripts. These distinct transcripts are thought to tailor the properties of the channel to the requirements of the cell. Presumably, a single splice variant cannot satisfy the specific needs of all cell types. To test this, we examined whether a single slowpoke splice variant was capable of complementing all slowpoke behavioral phenotypes. Null mutations in slowpoke cause animals to be semiflightless and to manifest an inducible "sticky-feet" phenotype. The well-characterized slowpoke transcriptional control region was used to direct the expression of a single slowpoke splice variant (cDNA H13) in transgenic flies. The endogenous gene in these flies had been inactivated by the slo(4) mutation. Action-potential recordings and voltage-clamp recordings demonstrated the production of functional channels from the transgene. The transgene completely complemented the flight defect, but not the sticky-feet phenotype. We conclude that distinct slowpoke channel isoforms, produced by alternative splicing, are not interchangeable and are required for proper function of different cell types.

Action Potentials↗
PubMed2000

Experience with Bailey-Dubow rodding in children with osteogenesis imperfecta.

AIM: The current report presents our experience with the use of Bailey-Dubow elongation rods in children with osteogenesis imperfecta. MATERIAL AND METHODS: 63 patients with osteogenesis imperfecta underwent a total of 186 primary intramedullary fixations with Bailey-Dubow rods during period 1984-1996. Most of them were inserted into the femur (54.3 %), followed by the tibia (38.2%) and the humerus (7.9%). Patients' age at operation ranged from 1-12 years and treatment-period varied from 1-10 years. RESULTS: Insertion into the femur showed the lowest complication rate (21.0%). Patients either suffered from knee-joint migration of the distal nail (3.9%), proximal nail migration (7.9%), detached T-pieces from the sleeve (7.9%) or chronical nail infection (1.0%). Complication rate after tibia rodding was markedly higher (52.1%). Knee joint migration appeared in 8.5% and the distal piece of the rod migrated proximally in 38.0%, in 31.0% accompanied by recurrent antecurve deformity. Growth arrest and no elongation occurred in 5.6%. Results after humerus operation were by far least satisfying. None of the nails elongated adequately. 8 of the 14 Bailey-Dubow rods (57.1 %) required reoperation caused by migration and chronic nail infection, whereas reoperation rates amounted to 17.8% after femur and 29.6% after tibia insertion. However, just one refracture happened after adequate trauma (road accident), so that an extraordinary success of fracture prevention has to be scored. CONCLUSIONS: We concluded that the use of Bailey-Dubow rods in early childhood can be recommended for the femur, whereas insertion into the tibia or humerus is associated with a considerable complication rate.

Child↗
PubMed2000

Clinical experience with quetiapine in elderly patients with psychotic disorders.

Quetiapine fumarate is a recently marketed atypical antipsychotic medication proved to be effective in the treatment of schizophrenia and schizoaffective disorder in the younger population. There is a paucity of studies of this drug in the elderly and more data are needed on the effects of quetiapine in this population, especially those with comorbid medical illnesses. Quetiapine was used to treat seven elderly hospitalized patients between 61 and 72 years of age who manifested signs of psychosis related to schizophrenia, schizoaffective disorder, or bipolar disorder. All patients had been treated previously with conventional antipsychotics or other atypical antipsychotics. Response was assessed by observation of patient's behavior. Four patients responded to treatment; three did not respond. Positive symptoms decreased markedly in all four responders. Negative symptoms showed marked decrease in two patients and moderate decrease in one patient. Preexisting extrapyramidal symptoms (EPS) diminished in three patients. Transient hypotension, dizziness, and somnolence occurred in two patients. No other side effects were noted. No adverse consequences occurred when lithium, carbamazepine, valproic acid, or venlafaxine was given concurrently. The reduction of positive and negative symptoms of schizophrenia and lack of significant EPS and minimal sedative, hypotensive, and anticholinergic side effects indicate that quetiapine may be a safe and effective medication for the elderly.

Aged↗
PubMed2000

Transcriptional control of Ca(2+)-activated K(+) channel expression: identification of a second, evolutionarily conserved, neuronal promoter.

Neuronal signaling properties are largely determined by the quantity and combination of ion channels expressed. The Drosophila slowpoke gene encodes a Ca(2+)-activated K(+) channel used throughout the nervous system. The slowpoke transcriptional control region is large and complex. To simplify the search for sequences responsible for tissue-specific expression, we relied on evolutionary conservation of functionally important sequences. A number of conserved segments were found between two Drosophila species. One led us to a new 5' exon and a new transcriptional promoter: Promoter C0. In larvae and adults, Promoter C0 was demonstrated to be neural-specific using flies transformed with reporter genes that either contain or lack the promoter. The transcription start site of Promoter C0 was mapped, and the exon it appends to the 5' end of the mRNA was sequenced. This is the second neural-specific slowpoke promoter to be identified, the first being Promoter C1. Promoter choice does not alter the encoded polypeptide sequence. RNAase protection assays indicate that Promoter C0 transcripts are approximately 12 times more abundant that Promoter C1 transcripts. Taken together, these facts suggest that promoter choice may be a means for cells to control channel density.

Animals↗
PubMed1999

Characterization of eleven novel mutations (M45L, R119H, 544delG, G145V, H154Y, C184Y, D289V, 862+5A, 1172delC, R411X, E459K) in the tissue-nonspecific alkaline phosphatase (TNSALP) gene in patients with severe hypophosphatasia. Mutations in brief no. 217. Online.

Hypophosphatasia is a rare inherited disorder characterized by defective bone mineralization and deficiency of serum and tissue liver/ bone/kidney tissue alkaline phosphatase (L/B/K ALP) activity. We report the characterization of tissue-nonspecific alkaline phosphatase (TNSALP) gene mutations in a series of 9 families affected by severe hypophosphatasia. Fourteen distinct mutations were found, 3 of which were previously reported in the North American or Japanese populations. Seven of the 11 new mutations were missense mutations (M45L, R119H, G145V, C184Y and H154Y, D289V, E459K), the four others were 2 single nucleotide deletions (544delG and 1172delC), a mutation affecting donor splice site (862 + 5A) and a nonsense mutation (R411X).

Alkaline Phosphatase↗
PubMed1999

[Ehlers-Danlos syndrome].

The Ehlers-Danlos syndrome (EDS) comprises a heterogenous group of nine hereditary connective tissue disorders, characterized by hyperelasticity of skin and hypermobility of joints to differing extents. The skin is easily injured and wound healing is delayed. The majority of EDS patients belong to EDS-types I-III. The pathogenesis in these cases is not known, although recent data suggest a role for collagen V. In contrast, the etiology of EDS-types IV, VI and VII has been found. While EDS IV is caused by a mutation in the collagen III gene, in EDS VI a mutation in the lysyl hydroxylase gene is present. In EDS VII, the underlying defect is a mutation in the collagen I gene. The EDS-types V, VII and X are very rare; their symptoms resemble those of EDS-type II.

Ehlers-Danlos Syndrome↗
PubMed1999

Homozygous alpha-thalassaemia and hypospadias--common aetiology or incidental association? Long-term survival of Hb Bart's hydrops syndrome leads to new aspects for counselling of alpha-thalassaemic traits.

UNLABELLED: Fetuses with homozygous alpha-thalassaemia develop Hb Bart's hydrops fetalis syndrome, which usually leads either to abortion or fetal/neonatal death. We report diagnosis, intrauterine transfusion therapy, neonatal intensive care management and long-term follow-up of a Vietnamese infant who survived Hb Bart's hydrops fetalis syndrome. During the first 2 years the child had normal development. In addition, the patient exhibited penoscrotal hypospadias. Despite a thorough endocrinological work-up the aetiology of genital ambiguity could not be elucidated. A review of the literature showed an association of homozygous alpha-thalassaemia and hypospadias in all surviving male children, suggesting a common aetiology for both entities. CONCLUSION: On the basis of our findings, we speculate that an unknown gene on chromosome 16 responsible for genital formation is altered in homozygous alpha-thalassaemia.

Chromosomes, Human, Pair 16↗
PubMed1999

Experience with the atypical antipsychotics--risperidone and olanzapine in the elderly.

There is paucity of published data regarding controlled trials with risperidone and olanzapine in elderly psychotic patients. Medical records of 151 hospitalized geropsychiatric patients (risperidone patients n = 114 and olanzapine patients n = 37) were analyzed for demographic data, target symptoms, doses, effects, side effects, comorbid medical conditions and concurrent medications. The mean age of the patients was 71 years. The male: female ratio was essentially the same for both groups. The mean daily dose was 3 mg for risperidone and 10 mg for olanzapine. 78% of the risperidone group and 75% of the olanzapine group appear to have responded to treatment. The discontinuation rates of medication was the same in both groups (22%). Adverse events were reported in 16-17% in both groups. It appears from this study that both risperidone and olanzapine are relatively safe and effective in geropsychiatric patients with comorbid medical illnesses. Controlled studies and head-to-head comparison studies are recommended.

Aged↗
PubMed1999

Spinal anaesthesia with gamma hydroxybutyrate. A study in a rat model.

Gamma hydroxybutyric acid, a central inhibitory neurotransmitter and a cerebral metabolite of gamma-aminobutyric acid, is present in high concentrations in the mammalian hypothalamus and basal ganglia. Its sodium salt gamma hydroxybutyrate has been effectively used as an intravenous anaesthetic agent, and as an oral sedative, and in the management of the alcohol withdrawal syndrome. In an animal model, using 72 Wistar strain rats allocated to one of six groups of 12 animals each, with implanted lumbar intrathecal catheters, we examined whether gamma hydroxybutyrate, 20% 40 microL (32 mg kg-1) administered alone or combined with fentanyl, gamma hydroxybutyrate 20% 20 microL (16 mg kg-1), fentanyl 0.005% 20 microL (4 mg kg-1) as an intrathecal bolus, provides intraoperative anaesthesia, comparable with that produced by intrathecal lignocaine. We demonstrated that gamma hydroxybutyrate, given by an intrathecal bolus in the rat model, produced reversible segmental antinociception, together with muscular relaxation of the abdominal wall and rear limbs. This is accompanied by moderate sedation without haemodynamic or respiratory depression. This agent may thus be promising for use as a spinal anaesthetic drug.

Anesthesia, Spinal↗
PubMed1999

Risperidone in the treatment of elderly patients with psychotic disorders.

The authors evaluated the safety, tolerability, and efficacy of risperidone in 103 elderly patients (mean age, 71 years) with schizophrenia (75%) or schizoaffective disorder (25%). Using the Extrapyramidal Symptoms Rating Scale (ESRS), Positive and Negative Syndrome Scale (PANSS), and Clinical Global Impression (CGI) scale, they conducted a prospective, open-label, 12-week trial in 14 psychiatric centers in the United States. Patients' symptoms were assessed at baseline and over a 12-week period. At endpoint, ESRS scores were significantly reduced, as were PANSS total and subscale scores. There were no clinically significant changes in electrocardiograms, laboratory test results, or vital signs. Risperidone was well tolerated and efficacious in elderly patients with schizophrenia or schizoaffective disorder.

Aged↗
PubMed1998

Behavioral and electrophysiological analysis of Ca-activated K-channel transgenes in Drosophila.

The slowpoke gene of Drosophila melanogaster encodes a Ca-activated K channel. This gene is expressed in neurons, muscles, tracheal cells, and the copper and iron cells of the midgut. The gene produces a large number of alternative products using tissue-specific transcriptional promoters and alternative mRNA splicing. We have described in great depth how transcription is regulated and are now cataloging the tissue-specificity of different splice variants. It is believed that the diversity of products serves to tailor channel attributes to the needs of specific tissues. Electrophysiological and behavioral assays indicate that at least some of these products produce channels with distinct properties.

Animals↗
PubMed1998

Ehlers-Danlos syndrome type VI: lysyl hydroxylase deficiency due to a novel point mutation (W612C).

Ehlers-Danlos syndrome type VI (EDS VI) is a rare autosomal recessively inherited disease of connective tissue. The characteristic symptoms are hyperflexibility of joints and hyperelasticity of skin together with marked scoliosis, ocular manifestations and involvement of the vascular system. The underlying biochemical defect in EDS VI is a deficiency in lysyl hydroxylase (PLOD) activity resulting from mutations in the PLOD gene causing a low hydroxylysine content in various tissues. We found that two out of three patients showed a recently described duplication of about 800 bp in their LH mRNA. In the third patient we identified a new point mutation (2036 G-->C) resulting in a substitution of tryptophan by cysteine in the highly conserved C-terminal region of the enzyme (W612C). In addition, this mutation destroys a restriction site of MwoI. Restriction analysis of the patient's cDNA with MwoI showed the sole occurrence of the mutated transcript, while one allele in his genomic DNA contained the MwoI restriction site. Restriction analysis of the genomic DNA of the unaffected parents displayed a heterozygous loss of the restriction site for MwoI in the mother while the DNA of the father appeared normal. Our study demonstrates that the new point mutation (W612C) in conjunction with a functionless allele, most probably a null allele, for the LH gene may explain the functional deficiencies seen in this patient.

Adolescent↗
PubMed1998

Psychiatric and neuropsychological abnormalities in Huntington's disease: a case study.

The authors describe an atypical presentation of Huntington's disease in a 55-year-old woman who manifested essentially psychotic and cognitive symptoms. A positive family history of Huntington's disease and DNA analysis helped to establish the diagnosis. The patient's psychotic symptoms improved with risperidone. The psychiatric and cognitive symptoms of Huntington's disease are reviewed.

Antipsychotic Agents↗
PubMed1998

Genotoxicity of bioremediated soils from the Reilly Tar site, St. Louis Park, Minnesota.

An in vitro approach was used to measure the genotoxicity of creosote-contaminated soil before and after four bioremediation processes. The soil was taken from the Reilly Tar site, a closed Superfund site in Saint Louis Park, Minnesota. The creosote soil was bioremediated in bioslurry, biopile, compost, and land treatment, which were optimized for effective treatment. Mutagenicity profiles of dichloromethane extracts of the five soils were determined in the Spiral technique of the Salmonella assay with seven tester strains. Quantitative mutagenic responses in the plate incorporation technique were then determined in the most sensitive strains, YG1041 and YG1042. Mutagenic potency (revertants per microgram extract) in YG1041 suggested that compost, land treatment, and untreated creosote soil extracts were moderately mutagenic with Arochlor-induced rat liver (S9) but were nonmutagenic without S9. However, the bioslurry extract was strongly mutagenic and the biopile extract was moderately mutagenic either with or without S9. A similar trend was obtained in strain YG1042. The strong mutagenic activity in the bioslurry extract was reduced by 50% in TA98NR, which suggested the presence of mutagenic nitrohydrocarbons. Variation in reproducibility was 15% or less for the bioassay and extraction procedures. Bioavailability of mutagens in the biopile soil was determined with six solvents; water-soluble mutagens accounted for 40% of the total mutagenic activity and they were stable at room temperature. The mutagenic activity in the bioslurry and biopsile samples was due to either the processes themselves or to the added sludge/manure amendments. The in vitro approach was effective in monitoring bioremediated soils for genotoxicity and will be useful in future laboratory and in situ studies.

Animals↗