Biomedical subjects
Publications and source records attributed to G Ronquist.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A separation system based on isotachophoresis is described for the cyanogenic glycoside linamarin in aqueous solution and in human urine. Isotachophoresis is a migration of a substance in an electric field, which is applied to a system of electrolytes of specific design. Detection is carried out by monitoring conductivity changes. However, for linamarin in urine, a preseparation procedure was necessary because of the high amount of electrolytes. This was performed by affinity chromatography on a silica sorbent column, with cyclohexyl as the functional group by which linamarin was retained. After elution from the column by methanol, a separation and quantitation of linamarin was possible by means of isotachophoresis. The method allowed determinations of urinary linamarin exceeding 100 microM, with a coefficient of variation of 13% at 500 microM.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Adenylate kinase (AK) activity and glutathione concentration were measured in cerebrospinal fluid (CSF) on three different occasions after the ictus in 16 patients with cerebral infarction. All patients displayed an unambiguous AK activity in their CSF within 48 h after the ictus while glutathione was present in 10 of the 16 patients. The mean AK activity among these patients was reduced by about 60% after 1 week and an additional smaller reduction took place after 3-4 weeks. The glutathione concentration in CSF of these patients showed a similar curve profile with time. The 9 patients who showed clinical signs of improvement had significantly lower values on all occasions for both AK and glutathione than those who did not improve or deteriorated. A corresponding reduction in AK activity with time was not observed in 3 patients with cerebral malignancies. The possibility was excluded that the enhanced AK activity in CSF was the result of an increased transfer of the enzyme from the plasma compartment. Instead of causal relationship was suggested between the appearance of AK in CSF and a disturbed brain cell metabolism. Repeated analyses revealed different curve profiles for ischemic and neoplastic brain lesions. The importance of sampling and handling the CSF material under standardized conditions is emphasized.
Thirteen patients with stroke and one with TIA had repeated examinations with computed tomography (CT) of the head, examination of the cerebrospinal fluid (CSF) for adenylate kinase, glutathione, lactate, and albumin and clinical evaluations during the first fortnight after onset. In 9 patients with cerebral infarction edema shown on the CT scans was maximal on days 2--5, after which it diminished. In 2 patients with intracerebral hemorrhage the edema appeared early as a zone of low-attenuation around the high-attenuation area. Most patients with large lesions deteriorated clinically during development of the edema. In 3 patients the CT scans were inconclusive, probably because the lesion was too small. Adenylate kinase activity was present in all CSF samples during the period 6 hours-5 days, while glutathione was occasionally present in the CSF in 12 of the 14 patients. These findings are believed to indicate cell swelling and a leak in the plasma membrane. Based on these observations, it is suggested that initial ischemic edema is intracellular in patients with cerebral infarction, and that adenylate kinase in CSF is a sensitive marker for this type of edema.
Activity of strictly intracellular enzymes in the cerebrospinal fluid (CSF) may indicate leakage from dysfunctional brain cells. Increased activity of adenylate kinase (AK) in the CSF is indicative of brain cell injury arising from several sources, among them orthognathic surgery. The mechanism in the latter case is obscure, but the use of an oscillating saw which generates vibrations, and the site of surgery close to the brain may be contributing factors. Anaesthesia may also play a role. In the present study, CSF-AK activity was measured after hysterectomy and was compared with activity after orthognathic surgery in two other studies. Four of 19 patients (21%) in the present study expressed pathological activity, compared with 34 of 47 (72%) orthognathic patients in the two other studies. No firm conclusion may be drawn from historical comparisons, and the difference in activity seen between the two types of surgery might not necessarily be the result of surgical factors. Until this is investigated further, however, we conclude that there may be a difference in postoperative CSF-AK activity between orthognathic and lower abdominal surgery.
We aimed to develop a model for studying membrane leakiness. A microdialysis technique was used to investigate rubidium-86 (86Rb) uptake in suspended human erythrocytes in vitro, with the aim of later applying the technique to in vivo studies. Suspensions were prepared from washed erythrocytes and 86Rb administered directly or via the microdialysis probe. The effects on 86Rb uptake of varying the haematocrit were measured. Erythrocytes were also treated with the K+ ionophore valinomycin or the Na+/K+-ATPase inhibitor ouabain. The effects on 86Rb uptake, microdialysate content of lactate and pyruvate, and erythrocyte content of 2,3-bisphosphoglycerate (2,3-BPG) were measured. Valinomycin dissipates the potassium gradient and activates Na+/K+-ATPase, demonstrated by decreased erythrocyte 86Rb uptake with increasing concentrations of valinomycin. This increased ion pump activity enhanced glycolysis, which was demonstrated by accumulation of pyruvate and lactate due to enhanced consumption of 2,3-BPG. The microdialysis technique is appropriate for in vitro studies of ion fluxes across cellular membranes.
The use of lithium as an exogenous marker to determine the dilution of nasal spray washing samples was investigated in vitro and in vivo. The correlation coefficient between the true and calculated dilution determined in vitro, using pooled secretions, was 0.99 (p less than 0.001). Thirteen washings from healthy subjects contained 5-22% secretion, while five washings from asymptomatic allergic patients contained 21-39%. The described application of exogenous lithium as a marker of dilution of nasal secretion seems a promising tool for use when a washing method is employed to take samples for biochemical investigations.
Prostasomes, small corpuscular organelles derived from the prostate gland, were isolated from human seminal plasma by means of ultracentrifugation and Sephadex G 200 chromatography to examine their interactive ability with mouse spermatozoa as assessed by free zone electrophoresis. During the run, human prostasomes and mouse spermatozoa approached each other and finally fused into one single peak that was not further dissociated. In some cases the fusion of prostasomes and spermatozoa failed to appear following pretreatment of prostasomes with monoclonal antibodies raised against these organelles.