PubMed Health⌕ Search

Biomedical subjects

L Brandes

Publications and source records attributed to L Brandes.

12 recordsLinked to original sources
PubMed2000

The Lurcher mutation of an alpha-amino-3-hydroxy-5-methyl- 4-isoxazolepropionic acid receptor subunit enhances potency of glutamate and converts an antagonist to an agonist.

A point mutation of the GluRdelta2 (A654T) glutamate receptor subunit converts it into a functional channel, and a spontaneous mutation at this site is thought to be responsible for the neurodegeneration of neurons in the Lurcher mouse. This mutation is located in a hydrophobic region of the M3 domain of this subunit, and this alanine is conserved throughout many of the glutamate receptors. We show here that site-directed mutagenesis of the homologous alanine (A636T; GluR1-L(c)) in the GluR1 AMPA receptor subunit alters its channel properties. The apparent potencies of both kainate and glutamate were increased 85- and 2000-fold, respectively. Furthermore, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)was converted from a competitive antagonist into a potent agonist. Our results demonstrate that a single amino acid within or near the putative second transmembrane region of the GluR1 subunit is critical for the binding/gating properties of this AMPA receptor.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1999

Phase II trial of N,N-diethyl-2-[4-(phenylmethyl)phenoxy]ethanamine.HCl and doxorubicin chemotherapy in metastatic breast cancer: A National Cancer Institute of Canada clinical trials group study.

PURPOSE: This multicenter phase II trial investigated the efficacy and toxicity of a combination of the novel intracellular histamine antagonist, N,N-diethyl-2-[4-(phenylmethyl)phenoxy]ethanamine.HCl (DPPE), and doxorubicin in patients with anthracycline-naïve metastatic breast cancer. Preclinical models and early single institutional studies suggested DPPE could potentiate the cytotoxicity of doxorubicin. PATIENTS AND METHODS: Forty-two women, 32 to 77 years old (median, 59 years), with anthracycline-naïve metastatic breast cancer were treated. Patients may have had one previous regimen of nonanthracycline chemotherapy, either in the adjuvant or metastatic disease treatment setting. DPPE (6 mg/kg) was administered as an 80 minute intravenous infusion with doxorubicin (60 mg/m(2)) given intravenously over the last 20 minutes of the DPPE infusion. Patients were premedicated with an antiemetic and sedating regimen. The DPPE/doxorubicin treatment was given every 21 days for a maximum of seven cycles. RESULTS: All 42 patients were assessable. Overall, toxicity was comparable to that expected with doxorubicin alone, with the exception of DPPE-related motion sickness, mild hallucinations, and cerebellar signs at the time of the infusion. These CNS side effects were manageable in an ambulatory care setting, improved with subsequent cycles of treatment, and did not usually require hospitalization. Four patients developed febrile neutropenia. Thirty-five patients received four or more cycles of chemotherapy. The overall response rate was 52.5% (95% confidence interval, 36% to 68%), with 9.5% complete responses (n = 4), 43% partial responses (n = 18), and 38% of patients with stable disease (n = 16). CONCLUSION: The antitumour effects of DPPE/doxorubicin the 52.5% response rate seems encouraging, particularly in consideration of the fact that a recently reported randomized National Cancer Institute of Canada Clinical Trials Group trial using single-agent doxorubicin 60 mg/m(2) in one of the treatment arms achieved a 31% response rate. Thus, a randomized phase III trial of doxorubicin versus doxorubicin plus DPPE is being conducted in this clinical setting.

Adult↗
PubMed1993

Overproduction of EcoRI and SpA::EcoRI fusion protein by Escherichia coli employing the combinations of three different types of multicopy plasmids: comparison of plasmid stabilities and product concentrations.

The copy numbers of the expression plasmids (pRTF309+ and pMTC48), the repression plasmids (pcI857 and pRK248cI) and the protection plasmid (pEcoR4) in recombinant E. coli JM103 were investigated. In the absence of the protection plasmid, the copy number of the expression plasmid dropped; in its presence, the copy numbers of the expression plasmids increased after gene expression by temperature-shift induction. The copy numbers of the repression plasmids were not influenced by the presence or absence of the protection plasmid. The copy number of the latter were not changed during temperature-induced gene expression. In the absence of the protection plasmid, the product concentration (EcoRI enzyme activity) was very low. With the plasmid combination pRTF309+, pRK248cI, and pEcoR4, the enzyme (EcoRI) activity was higher, but with the plasmid combination pMTC48, pRK248cI, pEcoR4, the enzyme (SpA::EcoRI) activity was highest.

Bacterial Proteins↗
PubMed1991

Monitoring and control of biotechnological production processes by Bio-FET-FIA-sensors.

Single and multisensor field effect transistors (FET) with a pH-sensitive Si/SiO2/Si3N4/Ta2O5-gate and reference electrode (for single sensor) were developed and used for manufacturing the following biological (Bio)-FETs: for glucose analysis, glucose oxidase-FET (GOD-FET); for urea analysis, urease-FET; and for cephalosporin C analysis, cephalosporinase-FET. The GOD-FETs were integrated into flow injection analysis (FIA) of the Eppendorf variables analyser (EVA) system and used for monitoring the glucose concentration in microbial cultivation and production processes with recombinant Escherichia coli K12 MF, recombinant E. coli JM103, Saccharomyces cerevisiae H620, and Candida boidinii. Urease-FET-FIA was used to monitor the urea concentration in a simulated cultivation of Cephalosporium acremonium and urease-FET-FIA and GOD-FET-FIA for the monitoring of urea and glucose concentrations in simulated S. cerevisiae cultivations.

Acremonium↗
PubMed1991

Mammalian neurons in dissociated cultures form clusters in the presence of retinal pigment epithelium.

The objective of this study was to investigate the cellular processes involved in the formation of the cytoarchitectonics of the retina. Neurons derived from the retina, spinal cord, cerebral cortex and hippocampus were grown in dissociated monolayer tissue culture using standard techniques. The cultures of retina were unique in that the neurons actively formed into cell clusters. On the other hand, cultures of neurons from the other regions of the CNS grew without forming any obvious histotypical pattern. Cell clusters consisted of an apparent monolayer of neurons above a population of flat cells and clusters were observed in retinal cultures derived from all species studied (mouse, cat and guinea pig). Each cluster was surrounded by whorls of fibroblasts; astrocytes (GFAP-positive cells) were often closely associated with clusters. Formation of clusters appeared to depend strongly upon the presence of cells derived from the retinal pigment epithelium (RPE) because the ability of retinal cells to form clusters was markedly impaired when the RPE was omitted from the cultures. Interestingly, monolayer cultures of neurons from other regions of the CNS could be induced to form clusters, but only when cells of the RPE layer were included at the time of plating. In cultures grown without the RPE layer, clusters did not form when media taken from cultures expressing clusters was used, indicating that the formation of clusters was not caused by a media-bourne factor. On the other hand, clusters did form when neurons without RPE were grown on feeder plates in which clusters had previously been expressed and the neurons subsequently killed by prolonged culturing or by treatment with kainic acid. Hence, physical contact between neurons and cells derived from the RPE appears critical for the formation of clusters. Our results suggest that the cellular processes underlying the formation of clusters may reflect those in the development of the retina in vivo. Thus, cluster formation may be a useful model for investigating the initial stages in the development of retinal cytoarchitecture.

Animals↗
PubMed1991

On-line determination of intracellular beta-galactosidase activity in recombinant Escherichia coli using flow injection analysis (FIA).

A flow injection analysis (FIA) system was developed for the determination of cytoplasmic beta-galactosidase activity in recombinant Escherichia coli. The FIA system and its application for on-line monitoring of beta-galactosidase production during cultivation of recombinant E. coli in a 60-l airlift tower loop reactor is described. The results demonstrate that an FIA assay in conjunction with a cell disintegration step can be applied successfully for on-line monitoring of intracellular protein formation.

Colorimetry↗
PubMed1987

Weekly cyclophosphamide and alternate-day prednisone: an effective secondary therapy in multiple myeloma.

Intravenous or oral cyclophosphamide, 150-250 mg/m2 (500 mg maximum), once per week with alternate-day oral prednisone, 100 mg, was given to 57 myeloma patients resistant to melphalan and prednisone (MP). Seven responses in 28 primary MP-resistant patients and ten responses in 29 secondary MP-resistant patients were observed. Previous response to MP was not a significant factor in predicting response to weekly cyclophosphamide and alternate-day prednisone. The results suggest that the regimen of weekly cyclophosphamide and alternate-day prednisone may be as effective as more aggressive regimens in the treatment of patients with myeloma who have failed MP therapy. However, a randomized trial would be required to determine the relative contributions of cyclophosphamide and prednisone to the effectiveness of this regimen.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1982

Experimental model for studies of continuous peritoneal'dialysis in uremic rabbits.

In this paper we describe an experimental model designed for studies of continuous ambulatory peritoneal dialysis (CAPD) in uremic rabbits. We preferred the study of uremic animals because it is not known whether peritoneal membrane differs between normal and uremic animals. Animals made uremic after bilateral nephrectomy could not survive on dialysis. Instead, partial nephrectomy of one kidney and partial (5/6) destruction of the cortex of the remaining kidney by electrocauterization provided a simple and reproducible model. CAPD resulted in adequate control of uremia but the animals showed significant decreases in total plasma proteins and weight. This model is suitable for studies of the metabolic complications of CAPD.

Animals↗
PubMed1979

Studies of crystalluria in recurrent calcium lithiasis.

The authors have studied the distribution and total volumes of large and small crystals in the urine of healthy individuals and of those who form stones. Studies carried out on randomly obtained specimens were as reliable in identifying differences as were fasting specimens. Stone forming individuals had a greater number of large crystals and a greater total volume of crystals in the urine than had healthy persons. The urine of stone forming patients who had received treatment showed no difference in crystal volume from that of a similar group who had not been treated, and the same was true of a group of stone forming patients studied before and 6 months after the start of treatment.

Calcium Oxalate↗
PubMedDate not supplied

Production of fusion protein SpA::EcoRI in batch culture in a 60-L airlift tower loop reactor.

Escherichia coli JM103 carrying the expression plasmid pMTC48, repressor plasmid pRK248, and protection plasmid pEcoR4 was grown in a 60-L working volume airlift tower loop reactor on M9 minimal medium. Production of fusion protein SpA::EcoRI was induced by a temperature shift from 30 to 38 (optimum), 40, or 42 degrees C. The following parameters were monitored: cell mass concentration (X), total cell counts (TCC), number of colony-forming units (CFU), concentrations of glucose, acetate, ethanol, pyruvate, lactate, succinate, amino acids, and ammonia, and soluble and total protein content, as well as product concentration (enzyme activity of the fusion protein), dissolved oxygen concentration, oxygen utilization rate (OUR), CO2 production rate (CPR), respiration quotient (RQ), and volumetric mass-transfer coefficients (kLa). Product formation by temperature shift was only observed if LB concentrate was added to the culture at the same time the aeration rate was increased to avoid oxygen-transfer limitation. No product accumulation was observed with glucose and ammonia supplementation. During gene expression, X and TCC increased, CFU decreased, acetate increased, and the primary metabolite (ethanol, pyruvate, lactate) concentrations as well as OUR and CPR passed a maximum while RQ changed only slightly. These facts indicate that, during gene expression, the metabolic activity of the cell passes a maximum, and after that it decreases. With increasing aeration rate, the volumetric productivity increased, but the specific productivity with respect to the cell concentration decreased.

Aerobiosis↗