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Biomedical subjects

G Johansson

Publications and source records attributed to G Johansson.

At least 145 records · Page 8Linked to original sources
PubMed1995

Partitioning of proteins in dextran/hydrophobically modified dextran aqueous two-phase systems.

Partitioning of proteins was studied in aqueous two-phase systems composed of the polymers dextran and hydrophobically modified dextran. The modified dextrans were benzoyl dextran with a degree of substitution of 0.17 and valeryl dextran with a degree of substitution of 0.20. Phase diagrams for the systems of dextran/benzoyl dextran and dextran/valeryl dextran were determined at room temperature. The proteins studied were beta-galactosidase, bovine serum albumin, beta-lactoglobulin, lysozyme, myoglobin and cytochrome C. The partition coefficients of a series of salts were determined in dextran/benzoyl dextran two-phase systems. The addition of salts had strong effect on the partitioning of proteins. This effect was related to protein net charge and the position of the ions in the Hofmeister series. Cross partitioning of bovine serum albumin was studied in a dextran/benzoyl dextran aqueous two-phase system.

Animals↗
PubMed1994

Flow injection assay for the neurotoxin beta-ODAP using an immobilized glutamate oxidase reactor with prereactors to eliminate glutamate interferences.

The neurotoxic amino acid, beta-N-oxalyl-L-alpha,beta-diaminopropionic acid (beta-ODAP,ODAP) was oxidized by immobilized glutamate oxidase (GlOD) to produce hydrogen peroxide. The peroxide reacts with Trinder reagent in a reactor with immobilized horseradish peroxidase to form a red-colored quinone imine dye, which was detected spectrophotometrically at 512 nm. Determinations were made in a flow injection (FI) setup consisting of four packed-bed enzyme reactors containing GlOD (20 microL), catalase (20 microL), GlOD (250 microL), and peroxidase (50 microL) in series. Glutamate is oxidized quantitatively in the first reactor, but the hydrogen peroxide is destroyed in the second so that interferences from this substrate are removed. This step destroys only a few percent of the ODAP in the sample. Most of the remaining ODAP is oxidized in the third reactor. Injections of 20-microL ODAP standards gave a response curve which was linear within the range 10-650 microM. Phosphate buffer extracts of grass peas (lathyrus sativus) were purified by centrifugation and membrane filtration. Samples were injected into the FI setup to assay the toxin at a rate of 20 samples per hour. The beta-ODAP content of a batch of dry seed corresponded to 0.74% (w/w) with a relative standard deviation of 2.8%. Thermal treatment of ODAP standards at 80-90 degrees C reduced the response to 62% of that before heating. The decrease is due to beta<-->alpha isomerization, and the experiment thus confirms that the method is selective for the toxic beta-isomer.

Amino Acid Oxidoreductases↗
PubMed1994

Effect of some poly(ethylene glycol)-bound and dextran-bound affinity ligands on the partition of synaptic membranes in aqueous two-phase systems.

Ligands with an apparent affinity for various structural elements on the surface of synaptic membrane fragments have been bound to the polymers poly(ethylene glycol) and dextran. The ligand-polymer derivatives have been included in aqueous two-phase systems composed of water, poly(ethylene glycol) and dextran. The uneven distribution of the polymers resulted in the concentration of the polymer-bound ligand in one of the two phases. The effect of the ligand-polymer on the partition of membranes was studied by using synaptic membranes from calf brain, obtained by standard centrifugation methods. By using ligand-containing two-phase systems for nine-step counter-current distribution of membranes, it was shown that the distribution behaviour of various parts of the membrane preparation could be affected. The distribution was followed by determination of opiate binding, acetylcholinesterase, and total membrane (using protein and light-scattering measurements).

Acetylcholinesterase↗
PubMed1994

Doxycycline carrageenate--an improved formulation providing more reliable absorption and plasma concentrations at high gastric pH than doxycycline monohydrate.

The effect of increased gastric pH (obtained by pre-treatment with omeprazole) on the bioavailability of doxycycline monohydrate and doxycycline carrageenate has been investigated in 24 healthy volunteers, using an open, randomised, four-treatment, four-period, cross-over, 2 x 2 factorial design. Each subject received a single dose of 100 mg of each of the doxycycline formulations with and without pre-treatment with omeprazole (40 mg daily for 7 days). The two formulations were bioequivalent (rate and extent) during fasting without omeprazole pre-treatment, whereas after omeprazole, the monohydrate showed a highly significant decrease in bioavailability (38% for AUC and 45% for Cmax) compared to the carrageenate formulation, which was not affected by prior administration of omeprazole. Many of the subjects did not reach a therapeutic plasma level of doxycycline during the combination of omeprazole and doxycycline monohydrate, and most adverse events (mainly gastrointestinal) were reported after this combination. As large populations of patients have a high gastric pH due to frequent use of H2-blockers, proton pump inhibitors and antacids, as well as to physiological achlorhydria, the decreased absorption of doxycycline monohydrate may well have a clinical impact, for example when the patients are treated with tetracyclines for an infection.

Adult↗
PubMed1994

Effect of a long-term change from a mixed to a lactovegetarian diet on human saliva.

The effects of this long-term dietary change on secretion rate, buffer capacity, concentration of sodium and potassium and amylase activity of stimulated parotid and whole saliva was studied in 20 healthy, normal-weight, non-smoking omnivores. Salivary counts of mutans streptococci and lactobacilli were also made. Dietary surveys were carried out and saliva samples collected before (baseline) and 3, 6 and 12 months after the dietary change as well as 3 yr after the end of the lactovegetarian diet period. The dietary data showed an increase in the consumption of fruits, vegetables and dairy products and a decrease in meat, fish, eggs, sweets and biscuits. These changes led to an increased intake of carbohydrates, fibre and water. After 12 months on the vegetarian diet, the secretion rate, buffer capacity and sodium concentration of whole saliva and the secretion rate of parotid saliva had increased significantly. At the 3-yr follow-up, the buffer capacity and sodium concentration were still elevated, while the secretion rate had almost returned to the baseline values. The potassium content of whole saliva showed a tendency to increase during the vegetarian diet period, but had decreased again at the 3-yr follow-up.

Adult↗
PubMed1994

Little impact of elective surgery on the incidence and mortality of ruptured aortic aneurysms.

Rupture of an abdominal aortic aneurysm is an important cause of death, particularly for men over 60 years of age. The aim of elective surgery for abdominal aortic aneurysms is to prevent future death from rupture of the aneurysm. The present study examines the influence of elective surgery upon the rate of rupture, comparing 1980 when little elective surgery was done and 1989 when considerably more elective surgery was performed in a well defined population. The rate of rupture and death from such a cause was not affected by the increased number of elective operations. It is concluded that the number of operations generally performed is too small to significantly affect the mortality from rupture. In order to decrease this mortality patients with a high risk of rupture should be found and offered elective surgery.

Age Distribution↗
PubMed1994

Effects of early placement of a single tooth implant. A case report.

A single tooth implant was placed in a boy aged 12 years and 3 months. The case has been followed for more than 4.5 years. The fixture did not move together with the adjacent teeth as the maxillary growth went on. There was no "loss" of marginal bone on the side of one adjacent tooth where the distance between implant and tooth was appropriate. But a "loss" of marginal bone (measured from the cemento-enamel junction) was noted on the other adjacent tooth where the fixture had been placed too close to the tooth.

Age Factors↗
PubMed1994

Functional deterioration and selenium-vitamin E treatment in myotonic dystrophy. A placebo-controlled study.

OBJECTIVES: The aim of the investigations was to study the effect of a combined selenium and vitamin E treatment in patients with myotonic dystrophy. DESIGN: A double-blind placebo-controlled trial. SUBJECTS: Twenty-seven patients with myotonic dystrophy divided into an experimental (n = 13) and a control (n = 14) group. INTERVENTIONS: The experimental group was given increasing doses for 4 months up to a maximum of 1.6 mg selenium and 800 mg vitamin E daily and the control group a corresponding number of placebo tablets. The total treatment period was 2 years. MAIN OUTCOME MEASURES: Muscle strength (knee extension, knee flexion, hand-grip), maximal walking speed for 30 m, function in daily activities (disability), well-being and cognitive functioning. RESULTS: Before treatment, muscle strength showed moderately or markedly reduced values as did maximal walking speed. Disability was most markedly demonstrated in instrumental ADL-activities. Spatial ability was reduced in the majority of patients. During the 2-year follow-up period, the hand-grip strength and maximal walking speed decreased in both groups (P < 0.01). The reduction was not significantly different according to an 'intention-to-treat-analysis'. However, there was a significantly larger decline (P < 0.01) in the left-hand grip strength in the control group when all the patients with complete treatment compliance were included. CONCLUSIONS: A useful set of measurements has been developed for following functional deterioration in myotonic dystrophy. No conclusive evidence of beneficial effects of selenium and vitamin E treatment has been produced.

Adult↗
PubMed1994

Anaesthesia for abdominal vascular surgery in patients with coronary artery disease (CAD), Part I: Isoflurane produces dose-dependent coronary vasodilation.

The effects of anaesthesia for major abdominal vascular surgery on coronary flow regulation and mechanisms of myocardial ischaemia were studied in 56 patients with CAD, using a randomized, partly double-blinded protocol. After induction with fentanyl (3 micrograms.kg-1) and thiopentone (2-4 mg.kg-1) and tracheal intubation, principal anaesthetics were nitrous oxide/oxygen (60/40) with isoflurane (n = 20), halothane (n = 19) or fentanyl (15-20 micrograms.kg-1) (n = 17). Conventional invasive techniques and coronary venous retrograde thermodilution were used to assess systemic and coronary haemodynamics. Coronary vascular resistance was estimated from myocardial oxygen extraction. Myocardial ischaemia was diagnosed by 12-lead ECG and/or anterior wall motion abnormalities by cardiokymography and/or myocardial lactate production. When adjustment of anaesthetic dose was insufficient for haemodynamic control, i.v. phenylephrine and nitroglycerine were administered to treat hypotension and hypertension or cardiac failure respectively. Measurements were performed at four specific intervals; awake, before surgery and 10 and 30 min after abdominal incision. Comparable changes of systemic haemodynamics and myocardial oxygen consumption were observed in the three groups. Coronary vasodilation was evidenced in isoflurane patients only and was linearly dose-dependent (P < 0.001). Partial Least Squares Projections to Latent Structures modelling with cross validation confirmed this dose-dependency and ruled out a clinically measurable influence by intervention drugs or simultaneous systemic haemodynamic abnormalities. The incidence of myocardial ischaemia during anaesthesia and surgery was comparable in the three groups (35, 37 and 24%, respectively) and there was an association with systemic haemodynamic aberrations in 19 of the 27 ischaemic episodes. In contrast to ischaemic halothane and fentanyl patients, isoflurane patients with ischaemia had significantly lower myocardial oxygen extraction (P = 0.008 and P = 0.001, respectively), indicating that the oxygen extraction reserve was not utilized in a normal way during ischaemia.

Abdomen↗
PubMed1994

Anaesthesia for abdominal aortic surgery in patients with coronary artery disease, Part II: Effects of nitrous oxide on systemic and coronary haemodynamics, regional ventricular function and incidence of myocardial ischaemia.

This study examines the effects of nitrous oxide on haemodynamics, anterior left ventricular (LV) function and incidence of myocardial ischaemia in abdominal vascular surgical patients with coronary artery disease. Forty-seven patients were randomly assigned to isoflurane-fentanyl anaesthesia with nitrous oxide-oxygen vs air-oxygen (control). Systemic and coronary haemodynamics, 12-lead ECG, LV anterior wall motion by cardiokymography (CKG) and myocardial lactate balance were recorded at four intervals: before and during anaesthesia and 10 and 30 minutes into surgery. Systemic haemodynamics were controlled by anaesthetic dose, and, when insufficient, by i.v. nitroglycerine (NG) in case of LV failure (PCWP > 18 mmHg) and by phenylephrine during hypotension. We found that nitrous oxide was associated with greater need for i.v. nitroglycerin (patients: P = 0.031, episodes P = 0.005) and more myocardial ischaemia (patients P = 0.012, episodes P = 0.001) despite systemic and coronary haemodynamics comparable to the control group. We conclude that nitrous oxide, known to have both sympathomimetic and cardiodepressive actions, produced cardiodepression in the face of sympathetic stimulation. Our study design did not allow to conclude if myocardial ischaemia was the consequence of increased wall stress or a reason for the observed LV dysfunction. The higher incidence of introperative myocardial ischaemia and need for NG did not cause increased cardiac morbidity.

Abdomen↗
PubMed1994

Change from mixed diet to lactovegetarian diet: influence on IgA levels in blood and saliva.

IgA concentrations in human plasma, and whole and parotid saliva were measured before and 3 months after a shift to a lactovegetarian diet in 20 volunteers (four men and 16 women mean age 44 yr, range 27-61). The major dietary trends observed were an increased intake of berries and other fruits, vegetables, and dairy products, and a decreased intake of fish, eggs, and meat; biscuits and buns; sweets; alcoholic beverages; coffee; and tea. The consumption of meat, fish, and eggs decreased to zero, showing that the participants had adopted a lacto-vegetarian diet. There was a decrease in fat, protein, sucrose, and alcohol intake and an increase in total carbohydrate and fiber intake. There was no significant change in energy, retinol equivalent, or zinc intake. Despite this change in diet, no significant changes were observed between the mixed diet period and the vegetarian diet period in IgA in plasma, 253 +/- 52 and 264 +/- 55; whole saliva, 2.5 +/- 0.4 and 2.4 +/- 0.4; or parotid saliva, 0.88 +/- 0.22 and 0.90 +/- 0.20 (mg/100 ml, mean values, 95% confidence interval). Moreover, the diet change did not alter the secretion rate in whole and parotid saliva, the secretion rate of IgA in whole and parotid saliva, or the protein content of whole saliva. However, the protein content of parotid saliva increased significantly. Thus, this major diet change was apparently not drastic enough or sustained long enough to cause a change in IgA levels.

Adult↗
PubMed1994

The effect of Salinum on the symptoms of dry mouth: a pilot study.

The effect of a new saliva substitute, Salinum, was tested in 37 patients with severe symptoms of reduced salivation. The majority of the patients had suffered from hyposalivation and dry mouth for more than 8 years. The saliva substitute consisted of a water soluble extract of linseed. The physical properties of this extract are similar to those of the glycoproteins of the salivary secretions. The patients used the saliva substitute for a seven days period. Prior to the use of the extract the patients reported that the most severe symptoms of decreased salivation were a feeling of dryness in the mouth and burning sensations in the tongue, pharynx and oesophagus, The majority of the patients reported that the use of Salinum reduced the symptoms of hyposalivation. Great variation in effect occurred from patient to patient. Generally the patients with the most severe symptoms experienced the greatest relief of the symptoms when they used Salinum. Although of short duration the results of this pilot study indicate that an extract of linseeds may compensate for some aspects of the consequences of reduced salivation. Further studies are needed to elucidate the feasibility of the extract as saliva replacement.

Adult↗
PubMed1994

Twenty-four-hour rhythms in relation to the natural photoperiod: a field study in humans.

The daily rhythms of salivary melatonin, salivary cortisol, and axillary body temperature were measured in nine healthy volunteers in midsummer, around the autumn equinox, and in midwinter, at a latitude of 60 degrees N. The aim was to find out whether these rhythms were dependent on variations of the natural daylength. The samples were collected every 2 hr during 24-hr periods in everyday conditions. The individual rhythms were characterized with the acrophase estimates of the best-fitting cosine curve models and with the half-rise and half-decline times calculated from the raw data. The melatonin and cortisol rhythms were delayed significantly (about 1 hr) in midwinter as compared with summer and autumn. The most advanced rhythms were found in autumn. The shifts of the melatonin and cortisol rhythms could be explained as a result of the changes of natural illumination. The overt temperature rhythms did not differ significantly among the sampling months. The lack of seasonal patterns in temperature rhythms probably primarily reflected the socially determined rest-activity cycles of the subjects.

Adult↗
PubMed1994

Complement activation is influenced by the membrane material, design of the dialyser, sterilizing method, and type of dialysate.

The complement system becomes activated during blood-membrane contact in the dialyser. This study was designed to evaluate to what extent the dialyser design, the sterilization method, and the type of dialysate influence complement as measured by C3d. Twelve patients were dialysed three times on each of four different dialysers. Two hollow-fibre dialysers made of cuprophane (Hf-CuE ethylene-oxide-sterilized, Hf-CuS steam-sterilized) were compared with two plate dialysers made of cuprophane (P-Cu) or polycarbonate (P-Pc). Five patients were dialysed with acetate and seven with bicarbonate. Differences in C3d between at start of dialysis and after 180 min were calculated. C3d was increased more by P-Cu than by the other dialysers (P < 0.012, n = 12). In the bicarbonate group, C3d was increased more by P-Cu than by Hf-CuS or P-Pc (P < 0.022, n = 7) and more by Hf-CuE than Hf-CuS (P = 0.013). In the acetate group, C3d was increased more by Hf-CuS and P-Cu than by P-Pc (P < 0.006, n = 5). In conclusion, complement activation during dialysis varied due to membrane material, membrane design, sterilization method, and dialysate composition.

Adult↗
PubMed1994

On-line computerized vectorcardiography monitoring of myocardial ischemia during coronary angioplasty: comparison with 12-lead electrocardiography.

BACKGROUND: With new interventions minimizing ischemic myocardial injury, accurate and reliable techniques for the detection and continuous monitoring of myocardial ischemia are essential. We compared two techniques used for the detection of myocardial ischemia during coronary angioplasty: on-line computerized vectorcardiographic (cVCG) monitoring and the standard electrocardiography (ECG) leads or the complete 12-lead ECG. METHODS: Thirty patients scheduled for routine angioplasty were included in the study. cVCG was recorded continuously. The electrodes were placed according to the lead system described by Frank and connected to a computerized system for on-line vectorcardiography. A 12-lead ECG was recorded simultaneously. The absolute variable spatial ST vector magnitude (ST-VM) and the relative variable spatial ST change vector magnitude (STC-VM) were calculated and compared with the standard 12-lead ECG for the detection of ischemia. RESULTS: The sum of deviation in ST segment in all 12 standard ECG leads correlated closely with STC-VM, irrespective of which artery was occluded. STC-VM indicated ischemia during the first balloon inflation in 87% of the patients and demonstrated ischemia in more patients than the standard 12-lead ECG. Myocardial ischemia was not demonstrated by ST-VM in five out of 26 patients with ischemia according to STC-VM. In these cases, mainly directional vector changes and fewer changes in magnitude were observed. CONCLUSION: Compared with 12-lead ECG, on-line cVCG is a more sensitive method of detecting myocardial ischemia during coronary angioplasty and the reading is easier and faster. Our results support STC-VM > or = 0.050 mV as the criterion for ischemia during angioplasty; ST-VM should be applied together with STC-VM.

Angina Pectoris↗