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Biomedical subjects

L Gustafsson

Publications and source records attributed to L Gustafsson.

14 recordsLinked to original sources
PubMed1992

Optimization of cervical cancer screening.

The aim of this study was to investigate how a screening program interacts with the dynamic natural history of cervical neoplasia in order to learn how screening for cervical cancer should be carried out most cost-effectively. For the purpose of optimization, the fundamental quantities of the natural history are the shape of the curve of age-specific prevalence rates of cancer in situ, and the duration of this stage before progression to invasive cancer. Since these quantities seem similar in different populations, the results probably can be generalized. Simulation studies revealed that optimal screening implies a nonperiodic schedule, and that this schedule is dependent not only on the number of screenings, but also on the efficiency of the screening rounds. With lower efficiency, the schedule should be concentrated into a shorter period. The effect of screening is also especially sensitive to the choice of age at the first and--to a smaller extent--last screening. The results concerning three different objectives also were compared, namely reduction of the cumulative number of invasive cancers, reduction of deaths due to cervical cancer, and reduction of years-of-life lost. The choice of objective also plays a role in the design of an optimal screening program. The theoretical approach in this analysis easily can be developed and accommodated to more complex individual situations such as prior screening histories and differing screening schedules in high- and low-risk women.

Adult↗
PubMed1992

Predictive validity of factors influencing the institutionalization of elderly people with psycho-geriatric disorders.

The predictive validity of certain items was tested with respect to their influence on the institutionalization of elderly people with psycho-geriatric disorders (n = 69). Twelve items measuring both the patient's condition and the exhaustion around the patient were tested. Two outcome measurements were used, the first measuring the number of patients who were institutionalized after the end of 12 months and the second measuring the number of days at an institution during 12 months. The items "Exhaustion of spouse" and "Supervision need" showed the highest correlation with institutionalization and predicted institutionalization, better than items describing the degree of dementia.

Aged↗
PubMed1990

Cytologic screening for cancer of the uterine cervix in Sweden evaluated by identification and simulation.

Parameters characterising the progression of cervical neoplasia were estimated from population-based cancer and mortality statistics in Sweden for 1958-1981 by means of a dynamic computer model. Proceeding from that model and these data, the incidence and prevalence curves were constructed, the effects of the extensive cytological screening measures introduced during the 1960s were assessed, and future gains due to the measures already undertaken up to 1981 could be simulated. About 4,000 cases of cancer in situ were diagnosed annually in Sweden after the end of the 1960s, most of them in women born later than 1919. The maximum reduction in the number of invasive cancers up to 1981 was 42% for women born in 1919-1923, but increased progressively for later birth cohorts and reached 69% for those born in 1934-1938. The corresponding reduction in mortality rates was of the same magnitude. The screening measures up to 1981 will ultimately result in a reduction of invasive cancer by about 12,500 cases and of the number of deaths due to this disease by about 4,100. Only a part of the total gain in the number of lives saved had been revealed at the end of the study period in 1981.

Adult↗
PubMed1990

Osmoregulation of the salt-tolerant yeast Debaryomyces hansenii grown in a chemostat at different salinities.

The intracellular solute composition of the salt-tolerant yeast Debaryomyces hansenii was studied in glucose-limited chemostat cultures at different concentrations of NaCl (4 mM, 0.68 M, and 1.35 M). A strong positive correlation between the total intracellular polyol concentration (glycerol and arabinitol) and medium salinity was demonstrated. The intracellular polyol concentration was sufficient to balance about 75% of the osmotic pressure of the medium in cultures with 0.68 and 1.35 M NaCl. The intracellular concentration of K+ and Na+, which at low external salinity gave a considerable contribution to the intracellular water potential, was only slightly enhanced with raised medium salinity. However, the ratio of intracellular K+ to Na+ decreased; but this decrease was less drastic in the cells than in the surrounding medium, i.e., the cells were able to select for K+ in favor of Na+. The turgor pressure, which was estimated on the basis of intracellular solute concentrations, was 2,200 kPa in cultures with 4 mM NaCl and decreased when the external salinity was raised, resulting in a value of about 500 kPa in cultures with 1.35 M NaCl. The maintenance of a positive turgor pressure at high salinity was mainly due to an increased production and accumulation of glycerol.

Glucose↗
PubMed1987

Effects of plasma hyperviscosity on skeletal muscle blood flow and blood viscosity in vivo.

The effect of plasma hyperviscosity on skeletal muscle blood flow and blood viscosity in vivo was studied. Blood flow and viscosity in vivo were determined in the isolated and vasodilated calf muscle of one hind limb in dogs. Plasma hyperviscosity was induced by suspending red blood cells in concentrated and isotonic solutions of low molecular weight dextran in saline. Viscosity in vivo was determined by comparing pressure-flow relationships for blood and a reference solution. Blood viscosity in vitro was determined in a Wells-Brookfield cone-plate viscometer. Determinations were made for plasma viscosities of 1.3, 2.2 and 4 cP. It was found that blood flow and viscosity in vivo were strongly dependent on plasma viscosity and that the effects in vivo could be predicted from values obtained in vitro.

Animals↗
PubMed1985

Intestinal hemodynamic effects of dextran-induced hyperviscosity in the cat.

A hyperviscous state with red cell aggregation and increased plasma viscosity was induced in cats by intravenous infusion of high molecular weight dextran. A segment of the small intestine was isolated with intact vascular and nervous supply and placed in a plethysmograph for determination of the intestinal tissue volume and capillary filtration coefficient. The intestinal blood flow was measured by a drop recorder unit. Measurements of intestinal blood flow, flow resistance and capillary filtration coefficient were performed during normotension and regional hypotension before and after infusion of high molecular weight dextran. After infusion of high molecular weight dextran, there was a twofold increase of blood viscosity and a threefold increase of plasma viscosity. Erythrocyte sedimentation rate exceeded 100 mm/h. Intestinal blood flow decreased by 35% during normotension and by 45% during regional hypotension. Intestinal flow resistance increased by 45% during normotension and by 65% during hypotension. The capillary filtration coefficient was not affected by the dextran infusion. It is concluded that the intestinal hemodynamic effects of high molecular weight dextran are mainly dependent of the increased plasma viscosity and that the number of perfused capillaries is not reduced by obstructing red cell aggregates.

Animals↗
PubMed1979

Quantitation of different cells in the epididymal fat pad of the rat.

To determine the number of adipocytes and cells developing into adipocytes (preadipocytes) in the epididymal fat pad of normal Sprague-Dawley rats, two methods were developed. Liberation of all cells from the tissue was obtained by a combination of lytic enzymes and mechanical treatment with only a limited loss of cell integrity; with large tissue masses, an initial perfusion was necessary. These cells were cultured in medium 199 supplemented with serum, glucose, insulin, a triglyceride emulsion, and methyl cellulose to form a culture medium with high viscosity in which it has been shown that the cells do no multiply. In this medium some of the cells developed into adipocytes and could be recognized and counted. The results show that there are about twice as many preadipocytes as mature adipocytes in the smallest rats examined (about 50 g). With increasing weight and age the mature adipocytes increased while the number of preadipocytes seemed to be constant up to a weight of about 150 g, after which they continuously diminished and could not be found in rats weighing more than 300 g. Here the number of mature fat cells had reached a constant level. These results are consistent with the formation of new preadipocytes up to a rat weight of about 150 g. In normal rats these cells successively fill up with triglyceride and disappear at a body weight of about 300 g when they have been transformed into mature adipocytes. The results are also consistent with the concept that no new adipocytes are formed spontaneously in the adult Sprague-Dawley rat. It was shown, however, that in media without methyl cellulose, isobutylmethylxanthine probably could induce the formation of new adipocytes in the cells isolated from all rats, including the heaviest (oldest). This finding shows that the potential of cells to develop into adipocytes also seems to exist in the adult rat under certain circumstances.

Adipose Tissue↗
PubMed1979

Polycythemia, viscosity and blood flow in working and non-working skeletal muscle in the dog.

The relationship between hematocrit and blood flow in the vasodilated working and non-working skeletal muscle at different perfusion pressures was studied. After acutely induced polycythemia in the flow decreased by 35% in the non-working muscle which was proportional to the increase of viscosity measured in vitro. In the working muscle there was only a small non-significant decrease of flow after polycythemia indicating flow improvement at increased hematocrit by rhythmic muscle contractions.

Animals↗
PubMed1978

Inhibition of acetylcholine release in guinea pig ileum by adenosine.

The effect of adenosine on cholinergic neuroeffector transmission was studied in the isolated guinea pig ileum. Adenosine caused a dose-dependent and inverse frequency-dependent inhibition of contraction responses to transmural nerve stimulation. Blockade of adrenergic neurotransmission did not alter the inhibitory effect of adenosine. Adenosine also inhibited contraction responses to serotonin, angiotensin and high potassium, but not the responses to acetylcholine, histamine or direct electrical stimulation of the smooth muscle cells. Adenosine had little effect on basal outflow of acetylcholine but inhibited markedly and reversibly the release of acetylcholine induced by nerve stimulation. Acetylcholine was determined with gas chromatography-mass spectrometry. The results provide direct evidence that adenosine inhibits cholinergic neuroeffector transmission in the gut by a prejunctional action on acetylcholine release. This may be of functional importance since adenine compounds are released during stimulation of intestinal nerves.

Acetylcholine↗
PubMed1976

On the mechanism of salt tolerance. Production of glycerol and heat during growth of Debaryomyces hansenii.

As glycerol was suggested as an osmotic agent in the salt tolerant Debaryomyces hansenii the concentrations of total, intracellular, and extracellular glycerol produced by this yeast was followed during growth in 4 mM, 0.68 M, and 2.7 M NaCl media. The total amount of glycerol was not directly proportional to biomass production but to the cultural salinity with maximum concentrations just prior to or at the beginning of the stationary phase. In all cultures the cells lost some glycerol to the media, at 2.7 M NaCl the extracellular glycerol even amounted maximally to 80% of the total. A distinct maximum of intracellular glycerol, related to dry weight or cell number, appeared during the log phase at all NaCl concentrations. As the intracellular calculated glycerol concentrations amounted to 0.2 M, 0.8 M, and 2.6 M in late log phase cells at 4mM, 0.68 M, and 2.7 M NaCl, respectively, whereas the corresponding analysed values for the glycerol concentrations of the media were 0.7 mM, 2.5 mM, and 3.0 mM, glycerol contributes to the osmotic balance of the cells. During the course of growth all cultures showed a decreasing heat production related to cell substance produced, most pronounced at 2.7 M NaCl. At 2.7 M NaCl the total heat production amounted to--1690 kJ per mole glucose consumed in contrast to--1200 and--1130 kJ at 4 mM and 0.68 M NaCl, respectively. The Ym-values were of an inverse order, being 129, 120, and 93 at 4 mM, 0.68 M, and 2.7 M NaCl respectively.

Ascomycota↗
PubMed1975

Potentiation by prostaglandins e1, e2, and f2alpha of the contraction response to transmural stimulation in the bovine iris sphincter muscle.

The contraction response to transmural stimulation in the bovine iris sphincter muscle was abolished by atropine but was left virtually unchanged by hexamethonium, and by adrenergic neuron and receptor blockers, indicating activation of postganglionic cholinergic nerve fibres. Low doses of prostaglandins e1, e2 and F2alpha (0.1-5.3 ng/ml) consistently and apparently in a dose-dependent manner enhanced the contraction response to transmural stimulation. Prostaglandins E1 and E2 were equipotent while F2alpha was at least 10 times less active. Within the same dose range the prostaglandins also enhanced the contraction response to exogenous acetylcholine, indicating that part of the enhancing effect of the prostaglandins on neuromuscular transmission was due to a postjunctional action. A spontaneous increase in tone of the preparation commonly occurred about 1 h after the beginning of the experiment. SC 19220, a potent antagonist of prostaglandin action, reduced the tone and the contraction responses as well as the enhancing effect of the prostaglandins. It is concluded that prostaglandins might serve the function of controlling neuroeffector transmission and muscular tone in the sphincter muscle of the bovine iris.

Acetylcholine↗