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Biomedical subjects

L Gustafsson

Publications and source records attributed to L Gustafsson.

At least 37 records · Page 2Linked to original sources
PubMed2001

Laparoscopic cholecystectomy versus mini-laparotomy cholecystectomy: a prospective, randomized, single-blind study.

OBJECTIVE: To analyze outcomes after open small-incision surgery (minilaparotomy) and laparoscopic surgery for gallstone disease in general surgical practice. METHODS: This study was a randomized, single-blind, multicenter trial comparing laparoscopic cholecystectomy (LC) to minilaparotomy cholecystectomy (MC). Both elective and acute patients were eligible for inclusion. All surgeons normally performing cholecystectomy, both trainees under supervision and consultants, operated on randomized patients. LC was a routine procedure at participating hospitals, whereas MC was introduced after a short training period. All nonrandomized cholecystectomies at participating units during the study period were also recorded to analyze the external validity of trial results. The randomization period was from March 1, 1997, to April 30, 1999. RESULTS: Of 1,705 cholecystectomies performed at participating units during the randomization period, 724 entered the trial and 362 patients were randomized to each of the procedures. The groups were well matched for age and sex, but there were fewer acute operations in the LC group than the MC group. In the LC group 264 and in the MC group 150 operations were performed by surgeons who had done more than 25 operations of that type. Median operating times were 100 and 85 minutes for LC and MC, respectively. Median hospital stay was 2 days in each group, but in a nonparametric test it was significantly shorter after LC. Median sick leave and time for return to normal recreational activities were shorter after LC than MC. Intraoperative complications were less frequent in the MC group, but there was no difference in the postoperative complication rate between the groups. There was one serious bile duct injury in each group, but no deaths. CONCLUSIONS: Operating time was longer and convalescence was smoother for LC compared with MC. Further analyses of LC versus MC are necessary regarding surgical training, surgical outcome, and health economy.

Bile Ducts↗
PubMed2000

Male-male competition and parental care in collared flycatchers (Ficedula albicollis): an experiment controlling for differences in territory quality.

Females are known to benefit from mate choice in several different ways but the relationship between these benefits has received little attention. The quality of resources provided by males, such as nest sites, and paternal care are often assumed to covary positively However, because the location of the nest affects the cost of parental care, these two benefits from mate choice can easily be confounded. To investigate the provisioning ability of successful competitors while controlling for differences in territory quality we removed early-settled pairs of collared flycatchers (Ficedula albicollis) and allowed replacement by later-arriving males or floaters (i.e.'poor competitors'). A control group of early-settled males (i.e. 'good competitors') had their females removed. Females paired to good competitors enjoyed a significantly higher reproductive success and tended to receive more parental assistance from their mates compared with females mated to poor competitors. Thus, some males seem able not only to compete successfully over resources but also to feed their offspring at a relatively higher rate. An alternative explanation, that poor competitors invested less in offspring quality in response to a lower share of paternity, could be rejected. The rate of extra-pair paternity did not differ between the two treatment groups. Our results suggest that male- male competition can sometimes facilitate female choice of superior care-givers. Thus, a female's benefit from choosing a competitive male may not be restricted to the quality of the resource he defends but can also include superior paternal care.

Animals↗
PubMed2000

Expression of escherichia coli otsA in a Saccharomyces cerevisiae tps1 mutant restores trehalose 6-phosphate levels and partly restores growth and fermentation with glucose and control of glucose influx into glycolysis.

The TPS1 gene, encoding trehalose-6-phosphate synthase (TPS), exerts an essential control on the influx of glucose into glycolysis in the yeast Saccharomyces cerevisiae. The deletion of TPS1 causes an inability to grow on glucose because of a hyperaccumulation of sugar phosphates and depletion of ATP and phosphate. We show that expression of the Escherichia coli homologue, otsA, in a yeast tps1 mutant results in high TPS activity. Although the trehalose 6-phosphate (Tre6P) level during exponential growth on glucose was at least as high as in a wild-type yeast strain, growth on glucose was only partly restored and the lag phase was much longer. Measurement of the glycolytic metabolites immediately after the addition of glucose showed that in spite of a normal Tre6P accumulation there was still a partial hyperaccumulation of sugar phosphates. Strong elevation of the Tre6P level by the additional deletion of the TPS2 gene, which encodes Tre6P phosphatase, was not able to cause a strong decrease in the sugar phosphate levels in comparison with the wild-type strain. In addition, in chemostat experiments the short-term response to a glucose pulse was delayed, but normal metabolism was regained over a longer period. These results show that Tre6P synthesis from a heterologous TPS enzyme can to some extent restore the control of glucose influx into glycolysis and growth on glucose in yeast. However, they also indicate that the yeast TPS enzyme, as opposed to the E. coli otsA gene product, is able to increase the efficiency of the Tre6P control on glucose influx into yeast glycolysis.

Bioreactors↗
PubMed2000

The importance of ATP as a regulator of glycolytic flux in Saccharomyces cerevisiae.

The control of glycolytic flux in the yeast Saccharomyces cerevisiae was studied by using permeabilized cells. Cells were harvested from chemostat cultures and, after removal of the cell wall, nystatin was used to permeabilize the spheroplasts. By this method it is possible to study the performance and regulation of a complete and functional metabolic pathway and not only a single enzymatic step. The results showed that ATP has a strong negative effect on glycolytic activity affecting several of the glycolytic enzymes. However, the main targets for ATP inhibition was phosphofructokinase and pyruvate kinase. Phospofructokinase was inhibited by ATP concentrations starting at about 1-2 mM, while pyruvate kinase required ATP levels above 2.5 mM before any inhibition was visible. These ATP concentrations were in the same range as measured for nitrogen- and glucose-limited cells cultivated in chemostat cultures. Other potential candidates as enzymes susceptible to ATP inhibition included hexokinase and enolase. The ATP:ADP ratio, as well as trehalose-6-phosphate levels, did not seem to influence the glycolytic activity.

Adenosine Diphosphate↗
PubMed2000

Diphtheria antitoxin response to DTP vaccines used in Swedish pertussis vaccine trials, persistence and projection for timing of booster.

Data from two Swedish pertussis vaccine trials with various combination vaccines were used to compare anti-diphtheria antitoxin concentrations over time between different vaccines, vaccine lots and vaccine schedules. The immune responses were measured with a validated ELISA method.Results are given for 1326 children, born 1992, that were recruited to the placebo (DT)-controlled Trial I which used a 2, 4, 6 month schedule. Two DTP acellular and one DTP whole cell vaccine were used. No DT boosters were given until 5 years of age. Trial II recruited children born 1993-94 and compared three DTP acellular vaccines with one DTP whole cell vaccine. Results are given for 306 children in a 2, 4, 6 month schedule and for 531 children in a 3, 5, 12 month schedule. The latter schedule gave significantly higher diphtheria antitoxin concentrations post third dose. The various DTP acellular vaccines and an inefficacious DTP whole cell vaccine gave lower antitoxin concentrations than both an efficacious DTP whole cell vaccine and the DT vaccine. The larger differences in antigen response between vaccines was reduced in the course of time. Generally, an initial rapid decline of antitoxin concentration was followed by a slower decline; the change typically occurring when the antitoxin concentration reached 0.13-0.16 EU/ml. The time needed to reach this level was between 6 and 10 months based on the initial vaccine response.A "best-fit" combined exponential regression model was used to predict the optimal timing for booster vaccinations against diphtheria.Our data support a 3, 5, 12 month schedule followed by a fourth dose 4-5 years after the third dose, depending upon the vaccine used.

Antibodies, Bacterial↗
PubMed2000

Microaerobic glycerol formation in Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae produces large amounts of glycerol as an osmoregulator during hyperosmotic stress and as a redox sink at low oxygen availability. NAD(+)-dependent glycerol-3-phosphate dehydrogenase in S. cerevisiae is present in two isoforms, coded for by two different genes, GPD1 and GPD2. Mutants for either one or both of these genes were investigated under carefully controlled static and dynamic conditions in continuous cultures at low oxygen transfer rates. Our results show that S. cerevisiae controls the production of glycerol in response to hypoxic conditions by regulating the expression of several genes. At high demand for NADH reoxidation, a strong induction was seen not only of the GPD2 gene, but also of GPP1, encoding one of the molecular forms of glycerol-3-phosphatase. Induction of the GPP1 gene appears to play a decisive role at elevated growth rates. At low demand for NADH reoxidation via glycerol formation, the GPD1, GPD2, GPP1, and GPP2 genes were all expressed at basal levels. The dynamics of the gene induction and the glycerol formation at low demand for NADH reoxidation point to an important role of the Gpd1p; deletion of the GPD1 gene strongly altered the expression patterns of the GPD2 and GPP1 genes under such conditions. Furthermore, our results indicate that GCY1 and DAK1, tentatively encoding glycerol dehydrogenase and dihydroxyacetone kinase, respectively, may be involved in the redox regulation of S. cerevisiae.

Aerobiosis↗
PubMed2000

Physiological effects of 5-hydroxymethylfurfural on Saccharomyces cerevisiae.

The physiological effects of 5-hydroxymethylfurfural (HMF) on Saccharomyces cerevisiae CBS 8066 in the presence and absence of furfural were studied. Experiments were carried out by pulse addition of HMF (2-4 g/l) as well as HMF (2 g/l) together with furfural (2 g/l) to batch cultivations of S. cerevisiae. Synthetic medium with glucose (50 g/l) as carbon and energy source was used. Addition of 4 g/l of HMF caused a decrease (approx. 32%) in the carbon dioxide evolution rate. Furthermore, the HMF was found to be taken up and converted by the yeast with a specific uptake rate of 0.14 (+/-0.03) g/g x h during both aerobic and anaerobic conditions, and the main conversion product was found to be 5-hydroxymethylfurfuryl alcohol. A previously unreported compound was found and characterized by mass spectrometry. It is suggested that the compound is formed from pyruvate and HMF in a reaction possibly catalysed by pyruvate decarboxylase. When HMF was added together with furfural, very little conversion of HMF took place until all of the furfural had been converted. Furthermore, the conversion rates of both furfural and HMF were lower than when added separately and growth was completely inhibited as long as both furfural and HMF were present in the medium.

Anaerobiosis↗
PubMed2000

Inhibition effects of furfural on aerobic batch cultivation of Saccharomyces cerevisiae growing on ethanol and/or acetic acid.

Physiological effects of furfural on Saccharomyces cerevisiae growing on ethanol (15 g.l(-1)) or acetate (20 g.l(-1)) as the carbon and energy source were investigated. Furfural (4 g.l(-1)), which was added during the exponential growth phase in batch cultures, was found to strongly inhibit cell growth on both carbon sources. No biomass formation occurred in the presence of furfural. However, furfural was in both cases converted to furfuryl alcohol and furoic acid, and growth resumed after complete conversion of furfural. During growth on ethanol, a rapid initial conversion of furfural to furfuryl alcohol was observed during the first few minutes after the addition of furfural, after which the conversion rate decreased to approximately 0.15 g.g(-1).h(-1) for the remaining conversion time. Acetaldehyde accumulated in the medium during the first few hours of conversion. Interestingly, addition of acetate after furfural addition resulted in an increased conversion rate of furfural and a higher carbon dioxide evolution rate, but no growth was observed until after complete conversion of furfural. Furfural addition to cells growing on acetate as the sole carbon source induced no formation of acetaldehyde, and the furfural conversion rate was lower than that on ethanol. The relationship between inhibition effects of furfural and NADH consumption is discussed.

Journal Article↗
PubMed1999

Characterization of Saccharomyces cerevisiae CBS 7764 isolated from rainbow trout intestine.

A wild-type Saccharomyces cerevisiae, strain CBS 7764, isolated from the intestine of rainbow trout, was analyzed with respect to general growth parameters and global protein expression. Characterization of this strain was of interest since previous data show non-typical S. cerevisiae cell surface properties and because data suggest a probiotic potential of CBS 7764. The heat production rate (dQ/dt), monitored by microcalorimetry, showed that the typical growth phases resulting from diauxic growth on glucose were present in the fish isolate. However, CBS 7764 differentiated from a reference strain by becoming limited in the respiratory phase as demonstrated by a plateau in the dQ/dt signal. The global protein expression, as studied by two-dimensional gel electrophoresis (2D-PAGE), revealed a large degree of resemblance of the fish isolate to the reference strain, however, also clear qualitative and quantitative expression differences were detected; e.g. 14% of the proteins differed in expression level by a factor of at least 2. In addition, the fish isolate expressed 12 unique proteins. The heat shock proteins, which for other organisms have been identified as important in mucosal colonization, were generally expressed to a higher level in CBS 7764.

Animals↗
PubMed1999

Conversion of furfural in aerobic and anaerobic batch fermentation of glucose by Saccharomyces cerevisiae.

The effect of furfural on aerobic and anaerobic batch cultures of Saccharomyces cerevisiae CBS 8066 growing on glucose was investigated. Furfural was found to decrease both the specific growth rate and ethanol production rate after pulse additions in both anaerobic and aerobic batch cultures. The specific growth rate remained low until the furfural had been completely consumed, and then increased somewhat, but not to the initial value. The CO(2) evolution rate decreased to about 35% of the value before the addition of 4 g x l(-1) furfural, in both aerobic and anaerobic fermentations. The decrease of the CO(2) evolution rate was rapid at first, and then a more gradual decrease was observed. The furfural was converted mainly to furfuryl alcohol, with a specific conversion rate of 0.6 (+/-0.03) g (furfural) x g(-1) (biomass) x h(-1) by exponentially growing cells. However, the conversion rate of furfural by cells in the stationary phase was much lower. A previously unidentified compound was detected during the conversion of furfural. This compound was characterized by mass spectrometry and it is suggested that it is formed from furfural and pyruvate.

Journal Article↗
PubMed1999

Fps1p controls the accumulation and release of the compatible solute glycerol in yeast osmoregulation.

The accumulation of compatible solutes, such as glycerol, in the yeast Saccharomyces cerevisiae, is a ubiquitous mechanism in cellular osmoregulation. Here, we demonstrate that yeast cells control glycerol accumulation in part via a regulated, Fps1p-mediated export of glycerol. Fps1p is a member of the MIP family of channel proteins most closely related to the bacterial glycerol facilitators. The protein is localized in the plasma membrane. The physiological role of Fps1p appears to be glycerol export rather than uptake. Fps1 delta mutants are sensitive to hypo-osmotic shock, demonstrating that osmolyte export is required for recovery from a sudden drop in external osmolarity. In wild-type cells, the glycerol transport rate is decreased by hyperosmotic shock and increased by hypo-osmotic shock on a subminute time scale. This regulation seems to be independent of the known yeast osmosensing HOG and PKC signalling pathways. Mutants lacking the unique hydrophilic N-terminal domain of Fps1p, or certain parts thereof, fail to reduce the glycerol transport rate after a hyperosmotic shock. Yeast cells carrying these constructs constitutively release glycerol and show a dominant hyperosmosensitivity, but compensate for glycerol loss after prolonged incubation by glycerol overproduction. Fps1p may be an example of a more widespread class of regulators of osmoadaptation, which control the cellular content and release of compatible solutes.

Biological Transport↗
PubMed1999

Effect of transplacentally acquired tetanus antibodies on the antibody responses to Haemophilus influenzae type b-tetanus toxoid conjugate and tetanus toxoid vaccines in Filipino infants.

BACKGROUND: Pregnant women in developing countries are vaccinated with tetanus toxoid (TT) to prevent neonatal tetanus. In populations in which the maternal TT-vaccination program is efficiently implemented, responses of the infant to TT and TT-conjugated vaccines such as Haemophilus influenzae type b (Hib) capsular polysaccaride (PS) TT-conjugate (Hib-TT) vaccine may be depressed. OBJECTIVES: To study the influence of transplacentally acquired anti-TT antibodies on responses to TT vaccination and to Hib-TT vaccine. METHODS: One hundred ninety-four healthy Filipino infants received three doses of a Hib conjugate (either Hib-TT, PRP-OMP or HbOC) with diphtheria-tetanus-pertussis vaccine (DTP) given simultaneously but in a separate syringe at the age of 6, 10 and 14 weeks (primary series). In addition 54 of the study children received a booster dose of Hib-TT at 9 months simultaneously with the measles vaccine. RESULTS: Transplacentally acquired anti-TT did not interfere with the anti-Hib PS antibody (anti-Hib PS) response to any of the conjugates. The transplacentally acquired anti-TT was not significantly associated with the concentration of anti-Hib PS either before or after the booster dose of Hib-TT. High concentrations (> or =1 IU/ml) of transplacentally acquired anti-TT inhibited the infants' anti-TT responses. CONCLUSIONS: High concentration of transplacentally acquired anti-TT did not depress anti-Hib PS responses to the Hib-TT vaccine. On the other hand the high anti-TT concentrations somewhat depressed the anti-TT responses of the infants. However, the anti-TT concentrations attained were in the protective range in all study children after either the primary series (DTP + Hib-TT) or the booster dose of Hib-TT.

Antibodies, Bacterial↗
PubMed1998

The importance of the glycerol 3-phosphate shuttle during aerobic growth of Saccharomyces cerevisiae.

Maintenance of a cytoplasmic redox balance is a necessity for sustained cellular metabolism. Glycerol formation is the only way by which Saccharomyces cerevisiae can maintain this balance under anaerobic conditions. Aerobically, on the other hand, several different redox adjustment mechanisms exist, one of these being the glycerol 3-phosphate (G3P) shuttle. We have studied the importance of this shuttle under aerobic conditions by comparing growth properties and glycerol formation of a wild-type strain with that of gut2 delta mutants, lacking the FAD-dependent glycerol 3-phosphate dehydrogenase, assuming that the consequent blocking of G3P oxidation is forcing the cells to produce glycerol from G3P. To impose different demands on the redox adjustment capability we used various carbon sources having different degrees of reduction. The results showed that the shuttle was used extensively with reduced substrate such as ethanol, whereas the more oxidized substrates lactate and pyruvate, did not provoke any activity of the shuttle. However, the absence of a functional G3P shuttle did not affect the growth rate or growth yield of the cells, not even during growth on ethanol. Presumably, there must be alternative systems for maintaining a cytoplasmic redox balance, e.g. the so-called external NADH dehydrogenase, located on the outer side of the inner mitochondrial membrane. By comparing the performance of the external NADH dehydrogenase and the G3P shuttle in isolated mitochondria, it was found that the former resulted in high respiratory rates but a comparably low P/O ratio of 1.2, whereas the shuttle gave low rates but a high P/O ratio of 1.7. Our results also demonstrated that of the two isoforms of NAD-dependent glycerol 3-phosphate dehydrogenase, only the enzyme encoded by GPD1 appeared important for the shuttle, since the enhanced glycerol production that occurs in a gut2 delta strain proved dependent on GPD1 but not on GPD2.

Aerobiosis↗
PubMed1998

Improved ethanol production by glycerol-3-phosphate dehydrogenase mutants of Saccharomyces cerevisiae.

The anaerobic performance of gpd1 delta and gpd2 delta mutants of Saccharomyces cerevisiae was characterized and compared to that of a wild-type strain under well-controlled conditions by using a high-performance bioreactor. There was a 40% reduction in glycerol level in the gpd2 delta mutant compared to the wild-type. Also the gpd1 delta mutant showed a slight decrease in glycerol formation but to a much lesser degree. As a consequence, ethanol formation in the gpd2 delta mutant was elevated by 13%. In terms of growth, the gpd1 delta mutant and the wild-type were indistinguishable. The gpd2 delta mutant, on the other hand, displayed an extended lag phase as well as a reduced growth rate under the exponential phase. Even though glycerol-3-phosphate dehydrogenase 2 (GPD2) is the important enzyme under anaerobic conditions it can, at least in part, be substituted by GPD1. This was indicated by the higher expression level of GPD1 in the gpd2 delta mutant compared to the wild type. These results also show that the cells are able to cope and maintain redox balance under anaerobic conditions even if glycerol formation is substantially reduced, as observed in the gpd2 delta mutant. One obvious way of solving the redox problem would be to make a biomass containing less protein, since most of the excess NADH originates from amino acid biosynthesis. However, the gpd2 delta mutant did not show any decrease in the protein content of the biomass.

Adenosine Triphosphate↗
PubMed1998

Catch-up primary vaccination with acellular pertussis vaccines in 3-4-year-old children--reactogenicity and serological response.

In order to evaluate the optimum number of doses for catch-up primary vaccination against pertussis, 248 Swedish children 3-4 years of age were randomized to receive either two or three doses of a three-component or a five-component acellular pertussis vaccine. Adverse reactions were mild, but increased with increasing number of doses, especially in a subgroup of 17 children with serological signs of earlier pertussis. There were no clinically significant differences between the two vaccines. Antibody levels against pertussis were higher after two doses in this age group than after three doses in infancy. A primary vaccination program for older children can use two instead of three doses.

Antibodies, Viral↗
PubMed1998

Levels of anti-pertussis antibodies related to protection after household exposure to Bordetella pertussis.

Vaccine efficacies against typical pertussis after household exposure to Bordetella pertussis were estimated to be 75.4% for an acellular five-component vaccine, 42.4% for an acellular two-component vaccine, and 28.5%, for a licensed US whole cell vaccine, compared to placebo. Logistic regression analyses demonstrated statistically significant correlations between clinical protection and the presence of IgG antibodies against pertactin, fimbriae 2/3 and pertussis toxin in pre-exposure sera. Multicomponent pertussis vaccines of proven high efficacy in recent Swedish NIAID-sponsored efficacy trials induced higher antibody levels against pertactin and fimbriae 2/3 than less efficacious vaccines. Anti-pertactin, anti-fimbriae 2/3, and anti-PT may be used as surrogate markers of protection for multicomponent acellular and whole-cell vaccines against pertussis.

Adhesins, Bacterial↗
PubMed1998

Yeasts isolated from the intestine of rainbow trout adhere to and grow in intestinal mucus.

The yeast strains Saccharomyces cerevisiae CBS 7764 and Debaryomyces hansenii Hf1 (CBS 8339), isolated from the intestine of rainbow trout, were studied with respect to adhesion to and growth in fish intestinal mucus. The level of adhesion was dependent on the physiologic state of the yeast culture. Growing cells of both strains adhered more strongly than nongrowing cells. This correlates with a previously shown shift in cell surface hydrophobicity of these yeasts. In addition, forces other than hydrophobic interactions may participate, as all strains tested adhered more strongly to the membrane lipid phosphatidylserine than to phosphatidylcholine and phosphatidylethanolamine. Debaryomyces hansenii Hf1 also adhered to the most hydrophobic of the neutral lipids present in mucus, while no adhesion was observed to the other neutral lipids or to the hydrophilic silica gel, again suggesting hydrophobic interactions. Finally, the fish-isolated yeasts grew rapidly in isolated fish intestinal mucus as the sole source of energy and nutrients.

Animals↗