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Biomedical subjects

A Larsson

Publications and source records attributed to A Larsson.

At least 163 records · Page 9Linked to original sources

Relationship between blood pressure, metabolic variables and blood flow in obese subjects with or without non-insulin-dependent diabetes mellitus.

BACKGROUND: To assess the relationship between systemic blood pressure, metabolic variables and adipose tissue blood flow, we studied 55 subjects before and 36 subjects after an oral glucose load (100 g). METHODS: The subjects were divided into four different groups: (a) young lean control subjects [age 31 +/- 1 years, mean +/- SE, BMI (body mass index) 22.7 +/- 0.4 kg m-2]; (b) young obese subjects (age 29 +/- 2 years, BMI 37.8 +/- 1.8 kg m-2); (c) middle-aged obese subjects (age 50 +/- 2 years, BMI 30.2 +/- 0.9 kg m-2); and (d) middle-aged obese non-insulin-dependent diabetic (NIDDM) subjects (age 54 +/- 2 years, BMI 30.0 +/- 0.7 kg m-2). RESULTS: Groups 2-4 demonstrated a low fasting adipose tissue blood flow (ATBF) and the increase in ATBF after oral glucose was impaired. A further impairment was present in NIDDM subjects. Systolic and diastolic blood pressure were also increased in groups 2-4 and further so in group 4. Fasting glucose, lactate and free fatty acid (FFA) levels correlated positively with the systolic blood pressure, whereas ATBF correlated negatively with the diastolic blood pressure. Furthermore, in the NIDDM subjects fasting lactate correlated closely with both the systolic (r = 0.649, P = 0.01) and diastolic (r = 0.626, P = 0.013) blood pressure. CONCLUSION: These data suggest a close relationship between insulin resistance and regulation of adipose tissue blood flow as well as blood pressure.

Adipose Tissue↗

Endotoxaemic liver injury in a porcine model--relation to tumour necrosis factor-alpha release and survival.

The effects of a continuous infusion of E. coli endotoxin on liver blood chemistry, plasma TNFalpha and blood pressure were evaluated in relation to survival in 18 anaesthetized pigs. The endotoxin infusion cause both unconjugated and conjugated bilirubin to increase (both p < 0.001), as compared to 6 saline-infused controls. Four pigs died during the endotoxin infusion. The plasma levels of TNFalpha of these 4 non-survivors were higher compared to TNFalpha of the 14 surviving endotoxaemic pigs (p < 0.05). The increase in plasma bilirubin of the non-survivors was less expressed (p < 0.05), and their arterial blood pressure and base excess deteriorated (both p < 0.001) compared to surviving endotoxaemic pigs. A decreased blood pressure explains both the reduced 'hepatic washout' of bilirubin and visceral ischaemia, reflected by the development of metabolic acidosis. This porcine model may be suitable for studying endotoxaemic liver injury.

Animals↗

Impaired platelet function in endotoxemic pigs analyzed by flow cytometry.

Endotoxin or bacterial lipopolysaccharide (LPS) is a structural component of Gram-negative bacteria. It is believed to be the major pathogenic factor of Gram-negative sepsis, and may result in intravascular coagulation and in a shock syndrome that is characterized by thrombocytopenia, leucopenia, hypotension, fever, reduced delivery of oxygen, metabolic acidosis and ultimately death. We have previously shown that both endotoxemic pigs and patients with Gram-negative sepsis have elevated levels of platelet microvesicles in their blood, which indicates platelet activation. In this study, we have used flow cytometry and fluorescein-labeled chicken anti-human fibrinogen to evaluate the in vivo effect of endotoxin on platelet function in a porcine model. Endotoxin infusion in pigs caused impaired platelet function when platelets were stimulated with adenosine-diphosphate in vitro ( P < 0.001). We also found a similarly decreased platelet function in patients with Gram-negative sepsis. Since flow cytometry is a rapid method for determination of platelet function, this method may turn out to be a useful tool in clinical situations. Our results may contribute to our understanding of the bleeding problems that may occur in septic shock and in disseminated intravascular coagulation.

Journal Article↗

Long-term effects of orthodontic magnets on human buccal mucosa--a clinical, histological and immunohistochemical study.

The aim of this intra-individual study was to examine human buccal mucosa clinically, histologically and immunohistochemically after 9 months' exposure to orthodontic magnets. In each of eight subjects (17.8-42.4 years), a magnet and a demagnetized equivalent of parylene coated neodymium-iron-boron was bonded alternately on the left and right side, to the buccal surface of maxillary premolars. The buccal mucosa was clinically examined and photographed, and three punch biopsies (6 mm diameter) of the buccal mucosa were taken from each subject at the site of contact with the magnet (test), in contact with the demagnetized magnet (control), and also at a site on the control side without contact with the demagnetized magnet (normal). The biopsies were snap-frozen for histological and immunohistochemical investigation, using antibodies to PD7 (lymphocyte 'naive T'), UCHL 1 ('memory T'), HLADR, ELAM-1 and ICAM-1. Clinically, the buccal mucosa showed normal features before and after the experimental period. In four of the eight subjects, the epithelium was 1.4-2.3 times thicker in the control and test tissues than in normal tissues. The difference between controls and tests was negligible, and there were no signs of increased keratinization or other surface abnormalities. Compared with normal sites, all control and test sites showed slightly increased ELAM-1/ ICAM-1 vascular staining, accompanied in three subjects by small infiltrates of PD7/UCHL 1-positive lymphocytic cells and in all subjects by focal keratinocyte HLADR-staining. The minor tissue reactions found in test and control tissues were interpreted to be a result of microtrauma (contact irritation) and not caused by the static magnetic field per se, since there was no difference between test and control tissues.

Adolescent↗

Uncompensated blood loss is not tolerated during acute normovolemic hemodilution in anesthetized pigs.

UNLABELLED: Clinically, hemodilution to a hematocrit of 9% has been studied, but the effects of hypovolemia during this degree of hemodilution have not been elucidated. We studied the response to blood loss during extreme hemodilution and evaluated indicators of hypovolemia. Systemic and myocardial hemodynamics, oxygen transport, and blood lactate concentrations were measured in 12 anesthetized pigs exposed to a graded blood loss of 10, 20, 30, and 40 mL/kg. Six animals were hemodiluted (hematocrit 10.8% +/- 1.4%, mean +/- SD), and six animals served as controls (hematocrit 34.6% +/- 1.5%). Hemodilution decreased systemic oxygen delivery to 9.5 +/- 0.6 mL x kg(-1) x min(-1) (controls 21.7 +/- 3.9 mL x kg(-1) x min(-1)) (P < 0.01) despite a 31% increase in cardiac output. Systemic oxygen uptake was unchanged. Arterial lactate increased to 3.3 +/- 1.1 mM/L (controls 1.6 +/- 0.6 mM/L) (P < 0.05), and mixed venous oxygen saturation (SvO2) decreased to 38.2% + 4.8% (controls 68.6% +/- 2.9%) (P < 0.01). At a blood loss of 10 mL/kg, cardiac output continued to be greater in the hemodiluted animals (P < 0.01). Arterial blood pressure decreased to 61 +/- 8 mmHg (controls 84 +/- 18 mm Hg) (P < 0.05), whereas heart rate was unchanged. Systemic oxygen delivery decreased to 8.8 +/- 1.2 mL x kg(-1) x min(-1) (controls 14.1 +/- 2.5 mL x kg(-1) x min(-1)) (P < 0.01). Systemic oxygen uptake was maintained by a further increase in oxygen extraction, and SvO2 decreased to 29.7% +/- 7.3%, compared with 55.3% +/- 9.0% in controls (P < 0.01). Arterial lactate increased to 4.9 +/- 1.4 mM/L (controls 1.8 +/- 0.8 mM/L) (P < 0.01). Myocardial oxygen delivery and lactate uptake were unchanged. When the blood loss equaled 30 mL/kg, myocardial lactate production occurred, and two hemodiluted animals died of circulatory failure. Central venous and capillary wedge pressures changed minimally during the blood loss and did not differ between groups. We conclude that a decrease in arterial blood pressure and SvO2 were early signs of hypovolemia during hemodilution, whereas central venous pressure and pulmonary capillary wedge pressure were insensitive indicators. IMPLICATIONS: Anesthetized pigs with extremely low hemoglobin levels (one third of normal) showed poor tolerance to blood loss >10 mL/kg. A decreasing arterial blood pressure, a decreasing oxygen saturation in the venous blood, and an increase in arterial blood lactate concentration were useful indicators of blood loss.

Anesthesia↗

Central and mixed venous blood oxygen correlate well during acute normovolemic hemodilution in anesthetized pigs.

BACKGROUND: Central venous oxygen saturation (ScvO2) and oxygen tension (PcvO2), obtained from the superior vena cava, correlate well with mixed venous (pulmonary arterial) oxygen saturation (SvO2) and tension (pvO2) when the hematocrit is normal. The present study was undertaken to assess whether extreme hemodilution affects this relation. METHODS: We compared mixed and central venous blood during graded arterial desaturation (inspired fraction of oxygen (FIO2) between 1.0 and 0.10) in 10 hemodiluted pigs, and in 10 pigs with normal hematocrit (control), during fentanyl-ketamine-pancuronium anesthesia and mechanical ventilation. RESULTS: Arterial oxygen saturation decreased from 100% at FIO2 = 1.0 to 44 +/- 12% at FIO2 = 0.10 (mean +/- SD). Venous oxygen saturation ranged from 3.5% to 97.3%. The regression coefficient between SvO2 and ScvO2 was 0.97 (R2 = 0.93, bias -2.4 +/- 5.8%) in the hemodiluted and 0.99 (R2 = 0.97, bias -3.0 +/- 5.0%) in the control group. Venous oxygen tension values ranged from 0.5 kPa to 9.5 kPa, and the regression coefficient for oxygen tension was 0.94 (R2 = 0.89, bias -0.20 +/- 0.47 kPa) in the hemodiluted and 0.99 (R2 = 0.97, bias -0.43 +/- 0.48 kPa) in the control group. The regression coefficient for pH was 0.95 in the hemodiluted and 0.98 in the control animals. CONCLUSION: The findings indicate that also during hemodilution monitoring of central venous blood oxygen may be as useful as monitoring of mixed venous blood oxygen.

Anesthesia↗

Retinyl palmitate injections reduce serum levels and effects of endotoxin on systemic haemodynamics and oxygen transport in the pig.

BACKGROUND: Retinyl palmitate [(RP) 230 IU.kg(-1)] modulates the circulatory and respiratory responses of a subsequent infusion of endotoxin in the pig. The aims of this study were: I. To determine if RP (2300 IU.kg(-1)) affects the serum endotoxin levels in this model. II. To evaluate the effect of this dose of RP on circulatory and respiratory variables in our porcine model. III. To investigate the levels of RP and neutrophil count in porcine endotoxaemia. METHODS: Ten anaesthetized pigs were randomly given 2300 IU.kg(-1) of RP or the solvent i.m. prior to the continuous i.v. infusion of E. coli endotoxin (10 microg.kg(-1).h(-1)). Another 4 sham animals were given either i.m. RP (n=2) or i.m. solvent (n=2) followed by an infusion of saline. Haemodynamics and oxygen extraction were monitored and samples taken for analysis of endotoxin, RP and blood cells. RESULTS: I. Endotoxin levels in serum were lower (P<0.001) in the RP-pretreated pigs. II. These animals had higher cardiac index (P<0.05), mean arterial pressure and left ventricular stroke work index (both P<0.001), and lower oxygen extraction (P<0.01). III. RP-Pre=pretreatment caused a paradoxical decrease in serum retinyl (P<0.001) and a more rapid restitution of neutrophil count (P<0.05). CONCLUSION: Pretreatment with RP (2300 IU.kg(-1)) counteracts the progressive increase in serum endotoxin levels in porcine endotoxaemia.

Animals↗

Increased platelet microvesicle formation is associated with mortality in a porcine model of endotoxemia.

BACKGROUND: Gram-negative sepsis in humans and endotoxemia in pigs induce the formation of platelet microvesicles. These microvesicles are active in homeostasis and may thus contribute to the outcome in patients with activated coagulation and fibrinolysis. We decided to prospectively evaluate the effects of endotoxemia on microvesicle formation and some common physiologic variables against survival in a porcine model. METHODS: Nineteen included pigs were anesthetized, monitored and subjected to an infusion of E. coli endotoxin. Microvesicle formation was determined by flow cytometry. RESULTS: The formation of microvesicles was significantly increased in the 6 pigs that died during endotoxin exposure. This increased formation became significant from the 3rd hour of endotoxemia. Microvesicle formation did not increase in surviving endotoxemic pigs. Cardiac index, mean arterial blood pressure, base excess and systemic vascular resistance index were distinctly reduced in the animals that died as compared to those surviving the endotoxemic period. CONCLUSION: The increased formation of platelet microvesicles seems to be associated with poor prognosis in porcine endotoxemia. Since microvesicles are active in coagulation, they may contribute to the derangement of the coagulation system caused by endotoxemia. Different degrees of microvesicle formation may reflect inter-individual responses to a given challenge.

Acidosis↗

Effects of recruitment of collapsed lung units on the elastic pressure-volume relationship in anaesthetised healthy adults.

BACKGROUND: The elastic pressure-volume (Pel-V) curve of the respiratory system can be used as a guide for improved ventilator management. The understanding of curves recorded for sick patients can be improved with better knowledge of the Pel-V relationship observed in healthy humans. Dynamic Pel-V curves were determined over an extended volume range in 15 anaesthetised and muscle-relaxed healthy humans. The influence of a recruitment manoeuvre was studied. METHODS: Dynamic Pel-V curves were determined during a single prolonged insufflation before and after the recruitment manoeuvre. A mathematical three-segment model of the curve including a linear intermediate segment, delineated by the lower (LIP) and upper (UIP) inflection points, was used for characterisation of the recorded curves. RESULTS: The model gave an adequate description of the recorded Pel-V curves. Before the recruitment manoeuvre, compliance increased until the LIP was reached at 20 cm H2O (1.9 L). Then followed a long linear segment. After the recruitment manoeuvre, compliance increased during insufflation until a LIP was reached at 13 cm H2O (1.2 L). Above the LIP followed a shorter linear segment (compliance = 140 mL/cm H2O) and then an upper segment with decreasing compliance. CONCLUSION: Pel-V curves recorded before and after the recruitment manoeuvre show that large lung compartments close during anaesthesia and that high pressures are needed to achieve recruitment even in the normal lung. Accordingly, the LIP does not define the end of recruitment during insufflation.

Adult↗

Immunohistochemistry of 'tertiary lymphoid follicles' in oral amalgam-associated lichenoid lesions.

OBJECTIVES: To characterise lymphoid follicle-like aggregates incidentally found to occur in biopsies of oral lichenoid reactions (OLR) and to correlate the findings to hyperplastic tonsil follicles. DESIGN: An immunocytochemical analysis of archival material. SUBJECTS AND METHODS: In an arbitrarily selected period 1992-1994 with a total of 13,924 oral biopsies, 2407 cases were signed out as OLR or lichen planus. These were microscopically reviewed, with the purpose to retrieve all cases showing histologic changes resembling secondary lymphoid follicles. RESULTS: 87 cases showed lymphoid follicle-like changes and 82 of these were in oral regions known to constitutively lack 'organised MALT'. Unexpectedly, all of the 82 were found retrospectively to be in close or direct contact with amalgam fillings. Immunocytochemically, using antibodies to B and T cells, macrophages, follicular dendritic cells and proliferation and apoptosis markers, the mucosal follicles stained similar to tonsillar secondary follicles. In several of an additional 11 OLR cases with histologic changes suggestive of primary follicles, we also found immunocytochemical evidence of such changes. CONCLUSIONS: 'Tertiary lymphoid follicles' may occasionally develop in OLR at sites of the oral mucosa constitutively lacking organised lymphoid tissue. The microenvironment of the OLR T cell infiltrate may occasionally favour such follicle development and amalgam constituents may causally be involved in an unknown way.

Dental Amalgam↗

Benefits of neonatal screening for congenital adrenal hyperplasia (21-hydroxylase deficiency) in Sweden.

OBJECTIVES: The aim of this study was to evaluate the benefits of neonatal screening for congenital adrenal hyperplasia (CAH). METHODS: All children with CAH born in Sweden from January 1989 to December 1994 were subjected to a systematic follow-up. Clinical symptoms were recorded and laboratory data collected. The clinical diagnosis versus diagnosis by screening was investigated. The results were compared with those of a retrospective study of all patients diagnosed during 1969-1986 (before the introduction of neonatal screening). RESULTS: The prevalence of CAH in Sweden was 1:9800 with screening. Patients with CAH were identified earlier by screening. Half of the infants (47%) were not diagnosed at the time of recall, which was 8 days (median). In the study population, 25% of the girls and 73% of the boys were diagnosed by screening alone. The median age at the time of the definite diagnosis in boys was 21 days before screening as compared with 9 days (median) during the last part of the screening period. During the screening period, only 1 boy had a severe salt loss crisis, which occurred at the age of 8 days. Before screening, (1969-1986) 2 boys had died in the neonatal period because of an adrenal crisis. The lowest serum sodium recorded at the time of diagnosis was 124 mmol/L (median; range, 93-148) before, as compared with 134 mmol/L (median; range, 115-148) after the introduction of screening. The number of girls who were initially considered to be boys was not reduced by screening (17% vs 18%). The period of uncertainty regarding gender attributable to virilization was shortened considerably, as well as the time it took to make a correct gender assignment: 23 days (median) before screening versus 3 days (median) with screening. The maximum time it took to make the correct gender assignment was 960 days before screening and 14 days with screening. The number of patients diagnosed late, ie, after the first year of life, decreased considerably after the introduction of screening. The false-positive rate (when a new filter paper blood sample was requested or when a child was referred to a pediatrician for follow-up) was <0.05% and in about 60% of the cases, it was attributable to preterm infants. The cost of screening was US dollar 2.70 per screened infant. CONCLUSION: The main benefits of screening were avoidance of serious salt loss crises, earlier correct gender assignment in virilized girls, and detection of patients who would have otherwise been missed in the neonatal period. Deaths in the neonatal period were prevented by screening. The aim of the screening program was to identify patients with the severe forms of CAH. Nevertheless, it must be considered a distinct benefit that a number of patients with milder forms of CAH were detected earlier, because earlier therapy results in decreased virilization, normalized growth and puberty, and, in all probability, an improved psychosocial situation for these children. We conclude that, in the Swedish health care system, the benefits of screening for CAH outweigh the costs.

17-alpha-Hydroxyprogesterone↗

Concordant message of different inflammatory markers in patients with rheumatoid arthritis.

The acute phase reaction is an unspecific response to inflammatory stimuli characterized by alterations in the concentration of several plasma proteins. It is of great clinical value to monitor the inflammatory state in patients with rheumatoid arthritis. The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are the assays most widely used to measure the acute phase response, but there are also several other inflammatory markers (e.g., fibrinogen, haptoglobin, alpha 1-acid glycoprotein, alpha 1-antitrypsin, interleukins (IL), serum amyloid component A (SAA)). We have studied the interrelationships between several of these markers (ESR, Haptoglobin, Fibrinogen, CRP, SAA and IL-6) in rheumatoid arthritis patients. There was a good correlation between all acute phase markers in serum (p < .01). We found especially strong correlations between S-CRP and SAA (p < .000001) and between ESR and P-fibrinogen (p = .000004). The strong correlation indicates that P-fibrinogen could be used instead of ESR in monitoring rheumatoid arthritis patients. This would increase the specificity of the examination as ESR may be influenced by several factors other than the inflammatory response. There were no significant correlations between acute phase markers in serum or plasma and clinical index.

Acute-Phase Proteins↗

Increased serum concentrations of carbohydrate-deficient transferrin (CDT) in patients with cystic fibrosis.

Carbohydrate-deficient transferrin (CDT) has been reported to be one of the best laboratory markers in serum (S) for detection of alcohol abuse. We have studied S-CDT values in cystic fibrosis (CF) patients and show that CF patients have increased S-CDT values without high alcohol consumption. CF patients have abnormalities in their protein glycosylation and sialylation, which may explain the increased S-CDT values.

Adolescent↗

Melagatran, a low molecular weight thrombin inhibitor, counteracts endotoxin-induced haemodynamic and renal dysfunctions in the pig.

Coagulation and fibrinolysis are crucial in septic shock and inhibition of thrombin may be beneficial in this circumstance. Since porcine endotoxaemia has been found to replicate severe septic shock, a low molecular weight thrombin inhibitor, melagatran, was infused during the first 3 out of 6 h of endotoxaemia in pigs. Plasma creatinine (p <0.01) and urinary output (p <0.05) were less affected in the melagtran + endotoxin group (n=6) as compared to endotoxaemic controls (n=9). The left ventricular stroke work index, systemic vascular resistance index and oxygen extraction were all less affected (p <0.05) by endotoxin during the infusion of melagatran. The plasma concentration of melagatran declined with an apparent plasma half-life of 5 h as soon as the infusion was stopped. APTT, however, continued to increase after the infusion of melagatran had stopped and reached a maximum of 113 s at 5 h (baseline 17 s). APTT in endotoxaemic control pigs reached a maximum of 22 s. Thus, melagatran may counteract some consequences of endotoxaemia.

Animals↗

Linkage analysis excludes familial congenital hypothyroidism from chromosome 21.

Congenital hypothyroidism (CH) is a heterogeneous disorder with largely unknown causes, affecting 1/3000-1/4000 new-borns. Individuals with Down syndrome have a much higher incidence of CH than the normal population, probably due to the extra copy of chromosome 21. Moreover, a girl has recently been described with CH and an interstitial deletion of proximal 21q, possibly revealing a recessive disease allele on the undeleted chromosome. To establish whether chromosome 21 is also involved in the etiology of familial cases of presumably autosomal recessive CH, we investigated 22 families with recessive CH, using 10 microsatellite markers from 21q. Linkage analysis allowing for heterogeneity revealed no signs of linkage even in a small proportion of the families, and two-point analysis of the markers made it possible to exclude the long arm of chromosome 21 from containing any major disease-causing gene.

Adult↗

Nephelometric determination of rat fibrinogen as a marker of inflammatory response.

Following tissue injury or infection, the concentrations of several plasma proteins are altered substantially. The characteristic pattern of this change is termed the acute phase response, and can be observed in many different inflammatory situations, including surgical trauma, injury, infections, tissue infarction and several immunologically mediated states such as temporalis arteritis, polymyalgia rheumatica and rheumatoid arthritis. It is often of great clinical value to monitor the acute phase response in humans but the assays used to measure the acute response in man (e.g., erythrocyte sedimentation rate and C-reactive protein) is less well suited for experimental studies in the rat. We have instead developed a nephelometric assay for determination of fibrinogen as a marker of the inflammatory response in rats. The assay was used to monitor the inflammatory response in type II collagen arthritis in rats. This model involves the induction of severe polyarthritis and is a widely used animal model for rheumatoid arthritis (RA). Fibrinogen concentrations increased from 3.1 g/l before immunization to 10.5 g/l 2 weeks after the immunization, after which they gradually declined towards normal levels. This pattern of fibrinogen alterations correlated well with the inflammatory phase of the arthritic response. Plasma fibrinogen may thus represent a rapid and sensitive marker of the acute phase response in the rat.

Acute-Phase Reaction↗

Regression analysis of simulated radio-ligand equilibrium experiments using seven different mathematical models.

The objective of this study was to investigate the conditions for regression analysis of data from equilibrium experiments. One important issue was to recognize that Kd and the binding site concentration (A) are not of equal nature, although both are parameters in the regression analysis. Whereas Kd approximates to a true constant, A is subject to experimental variation due to pipetting errors and in solid-phase experiments also to uneven coating properties. While recognizing that the ideal assumptions for ordinary regression analysis are poorly satisfied, different regression models were evaluated by extensive simulations. It was first established by a 'worst case' investigation that a limited error (8%) in the dependent variable is not critical for the results obtained at curve-fitting to Langmuir's equation. Seven different equations were compared for the calculation of data representing a solid-phase equilibrium experiment with statistical but no systematic errors. All the equations are rearrangements of the law of mass action. In this setting the Scatchrd plot gave the best result, but also the double reciprocal and the Woolf plots worked well in weighted analysis. Langmuir's equation gave the best result of the 4 nonlinear regression models tested. The influence of one type of systematic error was also investigated. This assumed that 10% of the label was positioned on particles other than the functional ligand molecules. This systematic error was amplified, which resulted in a substantial bias. The calculated Kd-values varied slightly with the regression method used and were almost 24% too high in the best methods.

Bias↗