Biomedical subjects

J Bengtsson

Publications and source records attributed to J Bengtsson.

At least 19 recordsLinked to original sources

PubMed2001

Biodiversity and ecosystem functioning: current knowledge and future challenges.

The ecological consequences of biodiversity loss have aroused considerable interest and controversy during the past decade. Major advances have been made in describing the relationship between species diversity and ecosystem processes, in identifying functionally important species, and in revealing underlying mechanisms. There is, however, uncertainty as to how results obtained in recent experiments scale up to landscape and regional levels and generalize across ecosystem types and processes. Larger numbers of species are probably needed to reduce temporal variability in ecosystem processes in changing environments. A major future challenge is to determine how biodiversity dynamics, ecosystem processes, and abiotic factors interact.

Animals↗

PubMed2001

Jejunal luminal nitric oxide during severe hypovolemia and sepsis in anesthetized pigs.

OBJECTIVE: Lowered gut blood perfusion and the associated intestinal mucosal barrier dysfunction is considered important in the pathophysiology leading to critical illness. Intestinal mucosal nitric oxide formation has been attributed a key role in the regulation of epithelial permeability and other properties of the intestinal mucosal barrier. This study was performed to delineate intestinal mucosal NO formation during hypovolemia or sepsis, both of which are associated with intestinal hypoperfusion. MATERIALS AND METHODS: Seventeen pigs were subjected to 2 h of severe hypovolemia (bleeding induced) or sepsis (systemic infusion of live Escherichia coli) or no treatment (controls). Jejunal mucosal NO production was monitored by a tonometer. Mesenteric blood flow was measured as portal venous blood flow by an ultrasonic transit time flowmeter probe, and oxygen delivery and consumption were calculated from regional blood samples. RESULTS: Intestinal perfusion and oxygen delivery were reduced by the same order of magnitude in both groups. Jejunal mucosal NO production and oxygen consumption decreased markedly in the hypovolemia group but remained stable in the group subjected to septic shock. CONCLUSIONS: These data suggest that blood loss inhibits jejunal mucosal NO production as part of a general downregulation of nonvital organs. Sepsis represents a more complex stress condition with activation/maintenance of host defense mechanisms as reflected by maintained jejunal mucosal NO production despite reduced gut blood perfusion.

Analysis of Variance↗

PubMed2001

Mitochondrial transcription factor A and respiratory complex IV increase in response to exercise training in humans.

Protein levels of mitochondrial transcription factor A (Tfam) and nuclear- and mitochondrial-encoded subunits of respiratory chain complex IV (COX I and COX IV) as well as citrate synthase activity were analysed in muscle biopsy samples of vastus lateralis in six healthy male subjects before and after 4 weeks of one-legged cycle training. One leg was trained with restricted blood flow. The other leg was trained with the same power profile but with non-restricted blood flow. Tfam, COX I and COX IV levels all increased with training, with no differences observed between the legs. The training-induced increase in citrate synthase activity was greater in the leg trained with restricted blood flow. These findings indicate that changed expression of Tfam protein could be one mechanism of exercise-induced mitochondrial biogenesis. The increases of COX I and COX IV indicate a concurrent increase of nuclear- and mitochondrial-encoded subunits of respiratory enzyme complex IV at the protein level in skeletal muscle in response to increased muscle activity. In this study, it was not possible to demonstrate that the greater energy disturbance induced by reduced blood flow further stimulates the expression of mitochondrial proteins, even though it did cause a greater enhancement of citrate synthase activity in concordance with earlier studies.

Adult↗

PubMed2001

End-tidal to arterial oxygen tension difference as an oxygenation index.

BACKGROUND: "Ideal" alveolar oxygen tension (PAO2) is a calculated entity and the alveolar-arterial oxygen tension difference (PA-aO2) is used to evaluate gas exchange function of the lungs. Accurate calculations of PAO2 necessitate measurements of the respiratory exchange ratio (RER), which is less frequently done, and most often approximations are made. The measured end-tidal oxygen tension (PETO2) is a reflection of the alveolar oxygen tension. The aim was to study the relationship between PAO2 and PETO2, and to see whether the end-tidal to arterial oxygen tension difference (PET-aO2) could give the same information about lung function as PA-aO2. METHODS: Twenty patients admitted for cardio-pulmonary exercise tests were studied. They bicycled for 4 min at each work load until maximum work load was reached. Arterial blood gases were analysed before, after 4 min at each work load, at maximum work load and after 2 min of recovery. A metabolic computer measured mixed expired gas concentrations. End-tidal gas concentrations were measured with a side stream gas analyser. RESULTS: We measured major increases in oxygen uptake, carbon dioxide elimination and RER. PAO2 and PETO2 increased at maximum exercise and during recovery. PAO2 and PETO2 were closely correlated during the study, through great changes in oxygen uptake and RER (r=0.88). When correction was made for wet gas the median difference was 0.12 kPa. CONCLUSIONS: At ambient air (FIO2=0.21), PET-aO2 as a respiratory index may give equivalent information to PA-aO2, without the need for measurements of mixed expired gas tensions or the hazard of an assumed RER.

Adult↗

PubMed2001

Monitoring of pacemaker induced changes in cardiac output with inspired to endtidal oxygen difference in paediatric cardiac surgery patients.

METHODS: Fourteen children aged 4-15 months were studied after corrective cardiac surgery. Heart rate was increased by 20% with an external pacemaker. Cardiac output (CO) was measured with thermodilution. Oxygen saturation was measured in systemic artery (SaO2), central vein (ScvcO2) and pulmonary artery (SvO2). Inspiratory to endtidal oxygen difference (FI-ETO2) was measured using a paramagnetic technique. SvO2 was measured continuously using a spectrophotometric technique. RESULTS: CO increased in three patients and decreased in 11 patients during pacing. Regression between DeltaCO and Delta(1/Sa-vO2), Delta(FI-ETO2/Sa-vO2), Delta(FI-ETO2/Sa-cvcO2) showed r=0.70, r=0.76 and r=0.75, respectively. DeltaCO exceeded 10% in 17 of 26 interventions. Changes in FI-ETO2 of equal direction as changes in CO occurred in 12 of these 17 interventions. CONCLUSION: Estimations of CO changes, based on SvO2, can be enhanced if changes in FI-ETO2 are also measured. ScvcO2 instead of SvO2 gives equivalent results. Sudden changes in FI-ETO2 after pacemaker initiation or termination can predict the direction of CO changes.

Carbon Dioxide↗

PubMed2000

Genes required for cytochrome c synthesis in Bacillus subtilis.

Cytochromes of c-type contain covalently bound haem and in bacteria are located on the periplasmic side of the cytoplasmic membrane. More than eight different gene products have been identified as being specifically required for the synthesis of cytochromes c in Gram-negative bacteria. Corresponding genes are not found in the genome sequences of Gram-positive bacteria. Using two random mutagenesis approaches, we have searched for cytochrome c biogenesis genes in the Gram-positive bacterium Bacillus subtilis. Three genes, resB, resC and ccdA, were identified. CcdA has been found previously and is required for a late step in cytochrome c synthesis and also plays a role in spore synthesis. No function has previously been assigned for ResB and ResC but these predicted membrane proteins show sequence similarity to proteins required for cytochrome c synthesis in chloroplasts. Attempts to inactivate resB and resC in B. subtilis have indicated that these genes are essential for growth. We demonstrate that various nonsense mutations in resB or resC can block synthesis of cytochromes c with no effect on other types of cytochromes and little effect on sporulation and growth. The results strongly support the recent proposal that Gram-positive bacteria, cyanobacteria, epsilon-proteobacteria, and chloroplasts have a similar type of machinery for cytochrome c synthesis (System II), which is very different from those of most Gram-negative bacteria (System I) and mitochondria (System III).

Amino Acid Sequence↗

PubMed1999

Bacillus subtilis contains two small c-type cytochromes with homologous heme domains but different types of membrane anchors.

We demonstrate that the cccB gene, identified in the Bacillus subtilis genome sequence project, is the structural gene for a 10-kDa membrane-bound cytochrome c(551) lipoprotein described for the first time in B. subtilis. Apparently, CccB corresponds to cytochrome c(551) of the thermophilic bacterium Bacillus PS3. The heme domain of B. subtilis cytochrome c(551) is very similar to that of cytochrome c(550), a protein encoded by the cccA gene and anchored to the membrane by a single transmembrane polypeptide segment. Thus, B. subtilis contains two small, very similar, c-type cytochromes with different types of membrane anchors. The cccB gene is cotranscribed with the yvjA gene, and transcription is repressed by glucose. Mutants deleted for cccB or yvjA-cccB show no apparent growth, sporulation, or germination defect. YvjA is not required for the synthesis of cytochrome c(551), and its function remains unknown.

Amino Acid Sequence↗

PubMed1999

Differentiation of the peptidergic vasoregulatory response to standardized splanchnic hypoperfusion by acute hypovolaemia or sepsis in anaesthetized pigs.

This study was performed to integratively investigate the vasoregulatory response during standardized splanchnic hypoperfusion in pigs. Splanchnic perfusion was reduced to 50% of baseline by: haemorrhage by 20 and 40% of the estimated total blood volume; femoral venous infusion of live E. coli to establish sepsis of systemic origin; portal venous infusion of live E. coli to establish sepsis of splanchnic origin. Invasive haemodynamic monitoring and radioimmunoassay analyses of arterial plasma concentrations of angiotensin II, endothelin-1 and atrial natriuretic peptide were carried out. Acute hypovolaemia reduced systemic and splanchnic vascular resistances following transient increases and increased angiotensin II levels (+587%), whereas endothelin-1 and atrial natriuretic peptide levels did not change significantly. Systemic sepsis following femoral venous infusion of E. coli resulted in increased splanchnic vascular resistance and increased levels of angiotensin II (+274%), endothelin-1 (+134%) and atrial natriuretic peptide (+185%). Infusion of E. coli via the portal venous route induced an increase in splanchnic vascular resistance associated with particularly elevated levels of angiotensin II (+1770%) as well as increased endothelin-1 (+201%) and atrial natriuretic peptide (+229%) concentrations. Hypovolaemia and sepsis, although standardized with a predefined level of splanchnic hypoperfusion, elicited differentiated cardiovascular and vasopeptidergic responses. Sepsis, particularly of portal origin, notably increased splanchnic vascular resistance related to increased production of the vasoconstrictors angiotensin II and endothelin-1. The role of atrial natriuretic peptide as a vasodilator seems to be of subordinate importance in hypovolaemia and sepsis.

Acute Disease↗

PubMed1999

Subunit II of Bacillus subtilis cytochrome c oxidase is a lipoprotein.

The sequence of the N-terminal end of the deduced ctaC gene product of Bacillus species has the features of a bacterial lipoprotein. CtaC is the subunit II of cytochrome caa3, which is a cytochrome c oxidase. Using Bacillus subtilis mutants blocked in lipoprotein synthesis, we show that CtaC is a lipoprotein and that synthesis of the membrane-bound protein and covalent binding of heme to the cytochrome c domain is not dependent on processing at the N-terminal part of the protein. Mutants blocked in prolipoprotein diacylglyceryl transferase (Lgt) or signal peptidase type II (Lsp) are, however, deficient in cytochrome caa3 enzyme activity. Removal of the signal peptide from the CtaC polypeptide, but not lipid modification, is seemingly required for formation of functional enzyme.

Amino Acid Sequence↗

PubMed1998

Epidemiology of acute vertebral osteomyelitis in Denmark: 137 cases in Denmark 1978-1982, compared to cases reported to the National Patient Register 1991-1993.

We studied the epidemiology of acute, non-tuberculous, hematogenous vertebral osteomyelitis in Denmark during 1978-1982. 137 patients fulfilled the criteria for acute vertebral osteomyelitis. The incidence was 5/mill/year. There were no cases in the age group 20-29 years. The highest incidence was between 60-69 years (18/mill/year). The prevalence was 15 cases. The mean duration of the disease was 7 months. The lumbar spine was affected in 59%, the thoracic spine in 33% and the cervical spine in 8% of the cases. Insulin-dependent diabetes and treatment with systemic corticosteroids seemed to be significant risk factors, but not rheumatoid arthritis and abuse of alcohol or intravenous drugs. We found no demographic variables of importance for the incidence. In 46%, a primary focus was identified, urinary tract infection being the commonest. According to the National Patient Register 1991-1993, the relative number of reported patients with vertebral osteomyelitis had increased in the age group 20-49 years, compared to 1978-1982, but the incidence was highest in the group aged 60-79 years.

Acute Disease↗

PubMed1997

The inspiratory to end-tidal oxygen difference during exercise.

OBJECTIVE: Fast paramagnetic oxygen analyzers have made it possible to measure inspiratory to end-tidal oxygen concentration difference (P(I-ET)O2) breath-by-breath. It is now frequently displayed on monitors during routine anesthesia. We wanted to study the effects of major changes in metabolism, ventilation and circulation on P(I-ET)O2. METHODS: Ten healthy male volunteers were studied under exercise. P(I-ET)O2 was measured with a fast-response paramagnetic differential oxygen sensor. Cardiac output was measured with non-invasive transthoracic electrical bioimpedance. Metabolism was measured with indirect calorimetry and ventilation with a side stream spirometer. After a rest period, the subjects cycled at 30 W and 60 W, 6 minutes on each work load and were then observed during 10 minutes of rest. RESULTS: P(I-ET)O2 corresponded well to VO2/VA (the oxygen uptake to alveolar ventilation quotient) correlation showed r = 0.79. P(I-ET)O2 was influenced by changes in cardiac output which occurred primarily at the start and at the end of exercise. Expired minute ventilation (VE) multiplied by P(I-ET)O2 was related to cardiac output with a high intrapersonal correlation. CONCLUSION: P(I-ET)O2 is a good measure of adequate ventilation in relation to the oxygen consumption level and multiplied by VE it might offer a non-invasive bedside parameter indicating changes in cardiac output.

Adult↗

PubMed1996

A study for testing the sensitivity and reliability of the Lysholm knee scoring scale.

The aim of the present investigation was to test the Lysholm knee scoring scale from 1985 for sensitivity and reliability. Thirty-one patients with one of four different diagnoses: anterior cruciate ligament rupture (ACL), meniscus tear (MT), patello-femoral pain syndrome (PFPS) and lateral ankle sprain (LAS) participated in the study. None of the patients were in the acute phase of injury, and none had undergone surgery. Each patient was interviewed by telephone and gave answers to the Lysholm knee scoring scale verbally, while the interviewer wrote down their replies. This was done on three different occasions, days 1, 3 and 14. The results showed that the ACL group scored the highest (81.1 of possible 100 points) and differed significantly (P < 0.01) from the other three groups. Thus, the Lysholm knee scoring scale was less sensitive for the ACL patients, for whom it was originally designed, than for the other three diagnostic categories. The reliability was highest between the two first testing times, day 1 and 3 (r = 0.75, P < 0.0001).

Adult↗

PubMed1995

Do changes in cardiac output affect the inspiratory to end-trial oxygen difference?

BACKGROUND: The paramagnetic technique has made it possible to monitor the end-tidal oxygen concentration and P(1-ET)O2, i.e. inspiratory to end-tidal oxygen difference, breath-by-breath. Little is known about the implications of a changing P(1-ET)O2, but so far studies have shown it to be a quick and sensitive variable to detect hypoventilation. This study was designed to observe the circulatory effects on P(1-ET)O2 in an experimental setting but monitored as in a clinical situation. METHODS: We assessed the oxygen difference during changes in cardiac output induced by intravenous ephedrine-hydrochloride in 12 healthy male volunteers. P(1-ET)O2 was measured with a fast-response paramagnetic differential oxygen sensor. Cardiac output was measured with non-invasive transthoracic electrical bioimpedance. As simultaneous changes in metabolism and ventilation will also influence P(1-ET)O2 oxygen uptake and expired minute volume were monitored. After a rest period, the subjects had an intravenous injection of ephedrine-hydrochloride 0.1 mg.kg-1 followed by a 30-min observation period. RESULTS: Cardiac output increased significantly as did the oxygen uptake and the ventilation. We found no biological significant correlation between cardiac output and P(1-ET)O2. The P(1-ET)O2 was influenced by ventilation and metabolism.

Adult↗

PubMed1995

Effects of ephedrine on oxygen consumption and cardiac output.

Bolus doses of ephedrine are often used by anaesthesiologists for intraoperative hypotension. This randomized single-blind cross-over study was designed to simultaneously evaluate circulatory, respiratory and metabolic effects of intravenously given ephedrine in 12 healthy male volunteers. Oxygen uptake and carbon dioxide excretion were measured with indirect calorimetry and non-invasive transthoracic electrical bioimpedance was used for cardiac output measurements. The maximum effect on most variables was reached at 4-5 min. At 5 min after the administration of ephedrine 0.1 mg per kilogram body weight, there were significant increases in cardiac index, systolic and mean arterial blood pressure, expired minute volume, oxygen uptake and carbon dioxide excretion rates. There were no significant changes in the quotient between oxygen uptake rate and cardiac index, VO2/CI during the 30 min study period. The O2 saturation was not altered. The present study indicates that ephedrine increases oxygen demand and supply in a similar magnitude.

Adrenergic Agents↗

PubMed1994

Effects of hyperventilation on the inspiratory to end-tidal oxygen difference.

We assessed the inspiratory to end-tidal oxygen difference (PIO2-PE'O2) during voluntary hyperventilation in 10 healthy male volunteers. The oxygen difference was measured with a fast-response paramagnetic differential oxygen sensor. As simultaneous changes in metabolism and cardiac output also influence (PIO2-PE'O2), oxygen uptake was measured with indirect calorimetry and non-invasive transthoracic electrical bioimpedance was used for measurement of cardiac output. After a rest period, subjects were instructed to double their minute ventilation volume (VE) and after 5 min triple their resting VE for another 5 min. (PIO2-PE'O2) decreased from a zero value of 6.4 kPa to 3.9 kPa at 5 min (P < 0.01) and 2.9 kPa at 10 min (P < 0.01). At 15 min (i.e. 5 min after the end of hyperventilation) there was an increase in (PIO2-PE'O2) to 8.3 kPa (P < 0.05). Regression analysis between (PIO2-PE'O2) (kPa) and VE (litre m-2 min-1) gave the formula: (PIO2-PE'O2) = 1/(0.059 + 0.034 VE), r = -0.92, n = 158. Oxygen uptake and cardiac output did not change significantly during hyperventilation, but decreased in the post-hyperventilation period. An oxygen difference of more than 8 kPa was associated with significant arterial desaturation.

Adult↗

PubMed1993

Sampled gas need not be returned during low-flow anesthesia.

OBJECTIVE: The purpose of this investigation was to study the N2 flux between the patient and the breathing circuit, and the excess gas during N2O anesthesia with the low, fresh gas flow technique. METHODS: Forty patients were studied. After a 6-minute high, fresh gas flow denitrogenation period, the O2 fresh gas flow was set at about 4 ml/kg/min and the N2O fresh gas flow was set to maintain an inspired O2 fraction of 0.30. The excess gas flow and N2 excretion were measured by a variant of the Douglas bag method. RESULTS: The mean inspired N2 concentration reached a peak of 5.9% at 40 minutes. The estimated mean N2 excretion was 39 ml/min at 10 minutes, declining to 18 ml/min at 60 minutes. A calculation of N2 homeostasis during closed-circuit anesthesia based on the results of the patient study indicated that sampling for gas analysis actually reduces the gas costs if the sampled gas is scavenged instead of returned to the circle system, since intermittent flushing with high, fresh gas flow for denitrogenation is unnecessary in the former situation. CONCLUSIONS: Regardless of the fresh gas flow used, sampled gas need not be returned during N2O anesthesia.

Adult↗

PubMed1993

[Respiratory gas exchange. Anesthesia with enflurane or isoflurane in nitrous oxide during spontaneous and controlled ventilation].

The estimation of oxygen consumption and carbon dioxide elimination is essential for predicting the metabolic activity and needs of any patient having anaesthesia. During anaesthesia oxygen consumption can be measured and compared to a predicted value. However, oxygen uptake is affected by anaesthetic agents, which complicates the interpretation of measured oxygen uptake rate. The purpose of this study was to investigate whether there are any differences in respiratory gas exchange during anaesthesia with enflurane and isoflurane and also to assess the effects of spontaneous versus controlled ventilation. METHODS. Forty orthopedic patients were randomized to enflurane or isoflurane anaesthesia in nitrous oxide with either spontaneous or controlled ventilation. A fresh low-gas-flow technique was used. Inspiratory oxygen and end-tidal carbon dioxide concentrations and expiratory minute ventilation were measured in a circle absorber system between the y-piece and the endotracheal tube with a sampling analyser. Between the mixing box and the absorption canister, carbon dioxide concentration was continuously measured. The carbon dioxide elimination was calculated from mixed expired concentration and expiratory minute ventilation. Excess gas was collected every 10 min in a non-permeable mylar plastic bag connected to the excess valve. The excess gas flow was calculated and the oxygen uptake rate was assumed to be the difference between the oxygen fresh gas flow and the oxygen excess gas flow. RESULTS. The grand mean oxygen uptake rate was 2.5 ml.kg-1 x min-1 or 100 ml.min-1 x m-2. There were no statistically significant differences in oxygen uptake between enflurane and isoflurane anaesthesia or between spontaneous and controlled ventilation. The mean oxygen uptake rate at 10 min was between 2.0 and 2.2 ml.kg-1 x min-1 in all groups. At 30 min the mean oxygen uptake rates were 2.6 to 2.8 ml.kg-1 x min-1. Carbon dioxide elimination was closely associated with expired minute ventilation, with a carbon dioxide excretion of about 30 ml per litre gas exhaled, irrespective of ventilatory mode employed.

Adult↗

PubMed1992

N-linked glycopeptides with blood group determinants lacking neuraminic acid from the epithelial cells of rat small and large intestine.

The N-linked type of glycans were prepared as their glycopeptides after pronase digestion of the epithelial cells from the small and large intestine of two inbred strains of rat. These glycopeptides were analysed for sugar composition, for blood-group activity, by 1H-NMR spectroscopy, and after permethylation by electron-impact mass spectrometry. The glycopeptides were of the triantennary and tetraantennary types with intersected GlcNAc. The terminal parts were, in contrast to most N-linked glycans, devoid of neuraminic acid residues. Instead they contained blood-group determinants. Blood-group-H types 1 (Fuc alpha 1-2Gal beta 1-3GlcNAc) and 2(Fuc alpha 1-2Gal beta 1-4GlcNAc) were found in the small and large intestines of both strains, although type-1 predominated. One rat strain (GOT-W) did not express blood-group-A glycopeptides in the small intestine, but the large intestine from the same strain did. The other strain (GOT-BW) expressed blood-group-A determinants in the small intestine. The lack of neuraminic acid residues in the small and large intestine and of blood-group-B activity in the large intestine differed from that found in glycosphingolipids obtained from the same organs.

Animals↗