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Biomedical subjects

E A Sanders

Publications and source records attributed to E A Sanders.

At least 37 records · Page 2Linked to original sources
PubMed1993

Studies on the production of human parathyroid hormone by recombinant Escherichia coli.

Expression of human parathyroid hormone, hPTH(-1-84), by Escherichia coli N4830:pEX-PPTH was studied in controlled bioreactors. The hPTH is expressed as a fusion protein under control of the bacteriophage lambda PR promoter. In batch runs, low biomass concentrations but high specific hPTH productivities were obtained with complex TY (bactotryptone and yeast extract) medium whereas high biomass concentration and low specific productivities were found when fructose was used instead of bactotryptone (YF medium). The preinduction temperature was always 30 degrees C; the temperature shift to induce production of fusion protein was varied from 36 to 42 degrees C. Formation of hPTH passed a pronounced maximum as a function of induction temperature when using YF medium. However, the optimum temperature shift was 38 degrees C for both media used. For this temperature increase both media yielded about the same volumetric hPTH productivity (approx. 30 mg hPTH/1 per hour). By applying a fed-batch strategy for the YF medium, the productivity of the recombinant protein could be further increased more than fourfold. Compared to shake-flask experiments, the hPTH yield could be increased by a factor larger than 20.

Biotechnology↗
PubMed1993

Control of microbial activity by flow injection analysis during high cell density cultivation of Escherichia coli.

The application of an automated flow injection analysis (FIA) system for on-line determination of microbial activity, during high cell density cultivations of Escherichia coli is reported. Based on a bioelectrochemical principle, the FIA method used a redox mediator (potassium hexacyanoferrate(III)) to facilitate electron transfer from the microorganisms to an electrochemical detector. Assays were carried out using a new sampling device which provided aseptic operation by use of a valve and chemical sterilisation. No sample dilution or pretreatment was necessary for biomass concentrations up to approx. 40 g l-1. The sample volume was 0.5 ml and the overall analysis time was 5 min. FIA signals were found to correlate well with the oxygen uptake rate (OUR). Changes in metabolic activity due to low substrate levels or high inhibitor concentrations in the cultivation medium became obvious from the FIA signals.

Bacteriological Techniques↗
PubMed1993

Diagnosing multiple sclerosis in childhood.

By presenting the cases of 3 children with laboratory supported definite multiple sclerosis [LSDMS] according to Poser's diagnostic criteria, we illustrate the difficulties of diagnosing MS in childhood. In search for appropriate diagnostic criteria for childhood MS, the literature on childhood MS is reviewed, and the 3 cases presented are compared with the 15 hitherto reported with the diagnosis LSDMS. Specific difficulties of diagnosing MS in childhood are discussed. They include history taking in children, the multiple differential diagnostic possibilities, and the various clinical presentations. Due to these specific difficulties in childhood MS, we conclude that a strict use of Poser's criteria is indispensable, especially in childhood MS.

Adolescent↗
PubMed1993

Repetitive injectable anesthesia in a 27-year-old horse.

A 27-year-old horse was anesthetized 3 times a week for 4 weeks, to facilitate cobalt therapy of a squamous cell carcinoma in the left paranasal sinus. Limitations of facilities required transport of the anesthetized horse to and from the cobalt therapy room, therefore, injectable anesthesia was used. Initially, the horse was preanesthetized with xylazine (at 1.1 mg/kg IV) and butorphanol (0.04 mg/kg IV). After 3 anesthetic episodes, the xylazine dose was reduced to 0.4 mg/kg IV and the butorphanol was deleted from the regimen. Tiletamine-zolazepam (1.1 mg/kg IV) was used for induction and maintenance of anesthesia (although on 2 occasions a bolus of ketamine was used to maintain immobility). The length of the procedure varied from 10-45 minutes, and the recovery times to sternal and standing varied from 23-76 and 55-105 minutes respectively. Although numerous complications might be expected given the age of this horse and the physiologic and metabolic demands of repetitive injectable anesthetics, none were observed.

Anesthesia, Intravenous↗
PubMed1992

[Good results in reoperation of recurrent radicular syndrome following surgery for herniated nucleus pulposus].

In the period 1985-1986 twenty-four patients with a recurrent lumbar disk herniation were subjected to surgery in the department of Neurosurgery in the Academic Medical Hospital of Utrecht. In 25% of these patients the second lumbar disk herniation was at the same level and side as the first one. Recurrence of the disk rupture at the same side and level as the first one occurred most often within two years after initial surgery. A recurrent slipped disk at different lumbar level occurred after a time interval of two years or more. Correct diagnosis depends on the results of imaging techniques. All reoperated patients did well after surgery and could return to their work or normal daily obligations.

Adolescent↗
PubMed1992

Psychiatric symptoms and mental changes as major features of multiple sclerosis.

A patient is presented with clinically and laboratory supported definite multiple sclerosis who developed severe depression followed by mental deterioration. Magnetic resonance imaging MRI demonstrated multiple hemispherical lesions. It is suggested that the psychiatric and cognitive signs and symptoms observed in this patient are due to severe cerebral demyelination.

Adult↗
PubMed1991

[Multiple sclerosis in childhood].

A 15-year-old girl presented with signs and symptoms indicative for multiple sclerosis. A final diagnosis could only be reached after 9 years follow up and with help of the MRI technique. The differential diagnosis of multiple sclerosis at a young age is discussed.

Adolescent↗
PubMed1991

Studies on the production of lipase from recombinant Staphylococcus carnosus.

Production of lipase from recombinant Staphylococcus carnosus pLipPS1 was studied in standard stirred tank bioreactors. Only low lipase activity was obtained under conventional operating conditions, i.e., moderate to high stirring speeds and aeration rates for keeping the dissolved oxygen concentration at high levels. Additional targetted experiments indicated that the reason for the observed low lipase activity is lipase inactivation due to surface forces and shear stress at the gas/liquid interface. Therefore, a cultivation strategy is proposed that minimizes gas/liquid interfacial area and maximizes the driving concentration for O2 mass transfer by controlling the dissolved oxygen to low values by gentle stirring and low aeration rates. Thus, high lipase activities can be obtained even in larger scale standard stirred tank bioreactors.

Fermentation↗
PubMed1991

High cell density cultivation of Escherichia coli at controlled specific growth rate.

A high cell density cultivation (HCDC) for growth of Escherichia coli in an especially designed glucose/mineral salt medium is proposed. The HCDC essentially starts as a batch process which is followed by a two-phase fed-batch cultivation. After unlimited growth at mu max = 0.45 h-1 in the batch part, growth was controlled at a reduced specific growth rate (mu = 0.11 h-1 less than mu max) over a period of 3 doubling times in which the biomass concentration increased from 12 to 95 g 1(-1) (phase 1 of fed-batch cultivation). Control of growth (mu) was realized by a PO2 control loop (by variation of glucose feeding) and a mu control loop (by variation of agitation speed N) while the actual mu was calculated from the off-gas composition. If the agitation rate cannot be increased anymore the mu controller is switched off (end of phase 1). In the following phase 2, mu declines, however, the still acting pO2 (glucose) controller guarantees sufficient O2 supply till the end of the cultivation with a biomass concentration of 110 g 1(-1) (dry mass). The proposed HCDC suppresses generation of inhibitory by-products and the high yield coefficients indicate the economy of the process.

Bacteriological Techniques↗
PubMed1991

Action of sympathomimetic drugs on the bronchial circulation of the horse.

In the quietly standing horse I.V. administration of adrenaline decreased, and of dobutamine increased, bronchial artery flow. These changes paralleled changes in arterial pressure. With phenylephrine and noradrenaline bronchial artery flow decreased while arterial pressure increased, indicating active vasoconstriction in the bronchial circulation. With clenbuterol an increase in bronchial artery flow was accompanied by a decrease in systemic blood pressure, indicating bronchial arterial vasodilatation. We conclude that alpha-constrictor and beta 2-dilator receptors are present in the bronchial artery bed and that stimulation of these receptors could explain changes in flow seen in the horse during exercise and anaesthesia.

Animals↗
PubMed1991

Anesthetic management for instrumentation of the pregnant rhesus monkey.

The anesthetic procedures used and the responses observed during maternal instrumentation on 38 pregnant rhesus monkeys (Macaca mulatta) during the second half of gestation are reported. A laparotomy with maternal instrumentation was performed in all animals. Anesthesia was induced with ketamine and maintained with halothane. Two animals delivered within five days of anesthesia and surgery and were unable to undergo experimentation. The remaining 36 animals underwent successful experimentation. Dysrhythmias, hypotension, and hypothermia were identified as complications of anesthesia.

Anesthesia, General↗
PubMed1991

[Juvenile dermatomyositis, systemic lupus erythematosus and mixed connective tissue disease].

This paper covers the current insights into the classification, etiology, management and prognosis of juvenile dermatomyositis (JDMS) systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). Since specific diagnostic tests for these autoimmune diseases are not available, diagnosis depends on the presence of defined criteria. Drug therapy in JDMS consists of prednisone at a low dosage (1 mg/kg/day). In SLE different therapeutic approaches are known depending on the occurrence of life threatening symptoms. The prognosis of MCTD is good, it is of prime importance to avoid overdosage of corticosteroids, since drug treatment is often not needed.

Adrenal Cortex Hormones↗
PubMed1990

Memory and learning in outpatients with quiescent multiple sclerosis.

In 22 (56%) of 39 quiet-stage multiple sclerosis (MS) patients with at least average intelligence quotients, performances in memory and learning tasks were normal, as compared with those of a control group (24 healthy volunteers). Of the remaining 44% (n = 17), 2 patients were amnesic and 5 had been judged to have suffered cognitive decline. Auditory word learning was particularly vulnerable; however, acquisition rate was not significantly different between MS patients and controls.

Adolescent↗
PubMed1990

Performances of multiple sclerosis patients in tasks requiring language and visuoconstruction. Assessment of outpatients in quiescent disease stages.

In a group of 39 multiple sclerosis (MS) patients with at least average intelligence quotients (IQ), performances were examined in tests requiring language usage and figure copying. Numbers of correct, digressive and erroneous responses were analysed and compared with those obtained in 24 healthy volunteers, matched to the patients group for socio-economic status. The examined specific tasks yielded no additional contribution to the prevalence estimation of cognitive deterioration (18%), as based on an assessment of general intelligence. Linguistic or cognitive-constructional problems were no more severe or more frequent in MS patients than those in control subjects. Upon writing or copying figures, pencil stroke and pencil pressure were deficient. Speed of reading aloud and of colour naming was decreased in the MS group, the most probable explanation being impaired control of the phonatory apparatus, oculomotor problems or weakness of colour vision. Decreases in speed of performance are not necessarily of cognitive origin. Differences between the present and previous reports based on similar tasks, appear to be connected partly with differences in patient selection. Of the present group, all MS patients were in quiescent disease stages, depression was mild or absent and physical handicap was less than in most studies reporting definite specific deficits.

Adult↗