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A Lindgren

Publications and source records attributed to A Lindgren.

At least 37 records · Page 2Linked to original sources

Perfusion-related parameters in intravoxel incoherent motion MR imaging compared with CBV and CBF measured by dynamic susceptibility-contrast MR technique.

OBJECTIVE: Perfusion-related parameters obtained by intravoxel incoherent motion (IVIM) MR imaging (MRI) were compared with cerebral blood volume and flow (CBV and CBF), retrieved by dynamic susceptibility-contrast (DSC) MRI. MATERIAL AND METHODS: Twenty-eight volunteers (average age 68.5 years) were investigated. Spin-echo echo-planar imaging with IVIM-encoding gradients was employed (36 different b values, 0-1200 s/mm2). The perfusion fraction and the pseudo-diffusion coefficient were calculated for regions in thalamus gray matter and frontal white matter, using asymptotic and full fitting. In DSC-MRI, a Gd-DTPA-BMA contrast-agent bolus was monitored using simultaneous-dual FLASH. Deconvolution of the measured tissue concentration-versus-time curve with an arterial input function from the carotid artery was applied, and maps of CBV and CBF were calculated. RESULTS: The correlation between the perfusion fraction and CBV was r=0.56 (p<0.0000006) using asymptotic fitting, and r=0.35 (p<0.0004) when full fitting was applied. Average CBF was 41.5 ml/(min 100 g), to be compared with the IVIM-based value of 63.6 ml/(min 100 g), obtained from the median value of the pseudo-diffusion coefficient in combination with assumptions about capillary network structure. CONCLUSION: The IVIM concept provided results that agreed reasonably with conventional CBV and CBF. The non-linear fitting to noisy signal data was problematic, in accordance with previously presented simulations.

Aged↗

The pachytene checkpoint in Saccharomyces cerevisiae requires the Sum1 transcriptional repressor.

Saccharomyces cerevisiae mutants that fail to complete meiotic recombination are blocked by the RAD17/RAD24/MEC1 checkpoint signaling pathway in pachytene when early sporulation genes are expressed. Middle genes are not activated in checkpoint-arrested cells because the Ndt80 transcription factor is inhibited. We find that the pachytene checkpoint requires Sum1, a transcriptional repressor that recognizes a subset of Ndt80-binding sites. Mutants lacking Sum1 or Rad17 partially bypass the block to the nuclear divisions but do not form spores, while mutants lacking both Sum1 and Rad17 completely bypass the block and form morphologically normal spores. The level of Sum1 protein decreases as middle genes are expressed, and this decrease is blocked in checkpoint-arrested cells. These data suggest that Sum1 levels are regulated by the checkpoint and that progression of the meiotic divisions and spore differentiation can be differentially controlled by competition of the Sum1 repressor and Ndt80 activator for occupancy at key middle promoters.

Blotting, Northern↗

[Evaluation of analytic test methods. Stomach-intestines status is the best diagnostic method in suspected vitamin B12 deficiency].

In the great majority of cases vitamin B12 deficiency is caused by chronic atrophic gastritis. This study has compared several different tests for the identification of patients for whom substitution therapy is needed or warranted. It is concluded that serum tests reflecting the state of the gastric body mucosa (serum pepsinogen A combined with serum gastrin or serum pepsinogen C) appear to be the logical first step in the workup of these patients in terms of high sensitivity and superior specificity as compared with other tests.

Biomarkers↗

Anisotropic orientation of horseradish peroxidase by reconstitution on a thiol-modified gold electrode.

Horseradish peroxidase (HRP) was reconstituted on the surface of a gold electrode that was modified first with a hemin-carbon-chain-thiol derivative followed by addition of the apo protein to the contacting solution. To facilitate the reconstitution of the holo enzyme, the hemin needs to be immobilised on a carbon-chain spacer arm. To achieve this, an immobilisation protocol was developed that is based on the initial formation of a mixed self-assembled monolayer on the gold surface consisting of 3-carboxypropyl disulphide and an activated disulphide (3,3'-dithiodipropionic acid di-(N-succinimidyl ester)) followed by binding of a diaminoalkane to the activated disulphide. The hemin was then coupled to the second amino group of the diaminoalkane by means of a carbodiimide coupling reagent. Finally, the enzyme was reconstituted on the hemin-modified surface by immersion of the electrode in a solution containing apo-HRP. The advantage of this method is that the length of the spacer arm can be changed easily, because diaminoalkanes of different chain lengths are available. The electrochemistry of the hemin and the reconstituted HRP electrodes was studied by means of cyclic voltammetry and differential-pulse voltammetry. The catalytic ability for reduction of hydrogen peroxide was investigated for both direct and mediated electrochemistry with a soluble electron donor (ortho-phenylenediamine).

Electrochemistry↗

The role of tobacco, snuff and alcohol use in the aetiology of cancer of the oesophagus and gastric cardia.

While tobacco and alcohol are established risk factors for oesophageal squamous-cell carcinoma, their roles in the aetiology of the increasingly common oesophageal adenocarcinoma remains uncertain. We tested the association between tobacco, snuff and alcohol use and the risk of oesophageal and cardia cancer in a nationwide, population-based case-control study in Sweden. Face-to-face interviews were conducted with 618 (81% of all eligible) patients (189 oesophageal adenocarcinoma, 262 cardia adenocarcinoma and 167 oesophageal squamous-cell carcinoma) and 820 control subjects. Odds ratios (OR) were calculated by logistic regression with multivariate adjustments for potential confounding. The risk of oesophageal adenocarcinoma was not associated with snuff or alcohol use, and the association with smoking was weak or absent. Gastric cardia adenocarcinoma was dose-dependently associated with smoking (OR=4.2, 95% CI=2.5-7.0 among heavy smokers compared with never-smokers), but not with alcohol or snuff use. Oesophageal squamous-cell carcinoma was strongly associated with tobacco, moderately with alcohol, but not with snuff use; combined use of tobacco and alcohol entailed a strongly increased risk (OR=23.1, 95% CI=9.6-56.0 among heavy users compared with never-users). We conclude that tobacco smoking, a strong risk factor for oesophageal squamous-cell carcinoma and cardia adenocarcinoma, does not play an important role in the aetiology of oesophageal adenocarcinoma. None of the studied exposures can explain the increasing incidence of oesophageal adenocarcinoma.

Adenocarcinoma↗

Assessment of regional cerebral blood flow by dynamic susceptibility contrast MRI using different deconvolution techniques.

Regional cerebral blood flow (rCBF) was assessed using dynamic susceptibility-contrast MRI at 1.5 T. A simultaneous dual FLASH pulse sequence and Gd-DTPA-BMA (0.3 mmol/kg b.w.) were used for examination of 43 volunteers, measuring rCBF in frontal white matter (WM) and in gray matter in the thalamus (GM). Arterial input functions (AIFs) were registered 1) in the carotid artery and 2) in an artery within the GM/WM slice. The measured concentration-vs. -time curve was deconvolved with the AIF using both Fourier Transform (FT) and Singular Value Decomposition (SVD). Relative rCBF was given by the height of the deconvolved response curve. For each volunteer, eight different rCBF maps were calculated, representing different combinations of deconvolution techniques, AIFs, and filters. The average GM-WM rCBF ratios ranged from 2.0-2.2, depending on methodology. Absolute rCBF was 68 +/- 28 ml/(min 100 g) in GM and 35 +/- 13 ml/(min 100g) in WM (mean +/- SD, n = 39). GM-WM rCBF ratios obtained using SVD were 6-10% higher than corresponding ratios obtained using FT.

Adult↗

Absolute cerebral blood flow measured by dynamic susceptibility contrast MRI: a direct comparison with Xe-133 SPECT.

Absolute regional cerebral blood flow (CBF) was measured in ten healthy volunteers, using both dynamic susceptibility-contrast (DSC) magnetic resonance imaging (MRI) and Xe-133 SPECT within 4 h. After i.v. injection of Gd-DTPA-BMA (0.3 mmol/kg b.w.), the bolus was monitored with a Simultaneous Dual FLASH pulse sequence (1.5 s/image), providing one slice through brain tissue and a second slice through the carotid artery. Concentration C(t) is proportional to -(1/TE) ln[S(t)/S(0)] was related to CBF as C(t) = CBF [AIF(t) x R(t)], where AIF is the arterial input function and R(t) is the residue function. A singular-value-decomposition-based deconvolution technique was used for retrieval of R(t). Absolute CBF was given by Zierler's area-to-height relation and the central volume principle. For elimination of large vessels (ELV), all MRI-based CBF values exceeding 2.5 times the mean CBF value of the slice were excluded. A correction for partial-volume effects (CPVE) in the artery used for AIF monitoring was based on registration of signal in a phantom with tubes of various diameters (1.5-6.5 mm), providing an individual concentration correction factor applied to AIF data registered in vivo. In the Xe-133 SPECT investigation, 3,000-4,000 MBq of Xe-133 was administered intravenously, and CBF was calculated using the Kanno Lassen algorithm. When ELV and CPVE were applied, DSC-MRI showed average CBF values from the entire slice of 43 +/- 10 ml/(min 100 g) (small-artery AIF) and 48 +/- 17 ml/(min 100 g) (carotid-artery AIF) (mean +/- S.D., n = 10). The corresponding Xe-133-SPECT-based CBF was 33 +/- 6 ml/(min 100 g) (n = 10). The relationships of CBF(MRI) versus CBF(SPECT) showed good linear correlation (r = 0.74-0.83).

Aged↗

Redox status of plasma homocysteine and other plasma thiols in stroke patients.

Despite the growing evidence that plasma homocysteine is a cardiovascular risk factor, the mechanism behind the vascular injuries is still unknown. Studies are difficult as a result of the fact that little is known about the formation of different homocysteine species in vivo. Since extracellular glutathione and cysteine may influence the formation of different homocysteine species, we have in the present study investigated the different fractions of homocysteine and their relation to the different fractions of glutathione and cysteine in stroke patients and control subjects. We found a ratio of about 32-33% between reduced and total plasma glutathione concentrations and 2.6 3.0% between reduced and total plasma cysteine concentrations both in patients and in healthy control subjects. We noted an elevated concentration of total plasma homocysteine in stroke patients, but no difference in the ratio between reduced and total plasma homocysteine concentrations in patients and control subjects (mean value 1.20 and 1.10%, respectively). However, in a subgroup of patients with higher concentrations of total plasma homocysteine, we observed a significantly lower ratio of reduced to total plasma homocysteine compared to a subgroup of patients with lower concentration of total plasma homocysteine. A low reduced/total ratio of plasma homocysteine in combination with elevated plasma homocysteine concentrations might reflect an increased pro-oxidant activity in plasma from these patients. Thus, increased pro-oxidant activity in plasma might be one factor, besides genetic and nutritional factors, that could explain hyperhomocysteinemia. Since substantial evidence indicates that progression of atherosclerosis is related to enhanced pro-oxidant activity, the premature vascular disease associated with increased plasma homocysteine concentration might be as a result of increased pro-oxidant activity and the elevated plasma homocysteine concentration may only reflect the increased oxidative stress.

Aged↗

Biosensors based on novel peroxidases with improved properties in direct and mediated electron transfer.

Native horseradish peroxidase (HRP) on graphite has revealed approximately 50% of the active enzyme molecules to be in direct electron transfer (ET) contact with the electrode surface. Some novel plant peroxidases from tobacco, peanut and sweet potato were kinetically characterised on graphite in order to find promising candidates for biosensor applications and to understand the nature of the direct ET in the case of plant peroxidases. From measurements of the mediated and mediatorless currents of hydrogen peroxide reduction at the peroxidase-modified rotating disk electrodes (RDE), it was concluded that the fraction of enzyme molecules in direct ET varies substantially for the different plant peroxidases. It was observed that the anionic peroxidases (from sweet potato and tobacco) demonstrated a higher percentage of molecules in direct ET than the cationic ones (HRP and peanut peroxidase). The peroxidases with a high degree of glycosylation demonstrated a lower percentage of molecules in direct ET. It could, thus, be concluded that glycosylation of the peroxidases hinders direct ET and that a net negative charge on the peroxidase (low pI value) is beneficial for direct ET. Especially noticeable are the values obtained for sweet potato peroxidase (SPP), revealing both a high percentage in direct ET and a high rate constant of direct ET. The peroxidase electrodes were used for determination of hydrogen peroxide in RDE mode (mediatorless). SPP gave the lowest detection limit (40 nM) followed by HRP and peanut peroxidase.

Arachis↗

Body size in different periods of life, diabetes mellitus, hypertension, and risk of postmenopausal endometrial cancer (Sweden).

OBJECTIVE: To measure the association between endometrial cancer risk and obesity at age 18 and recently, adult weight gain, diabetes mellitus and hypertension. METHODS: We performed a population-based, nationwide case-control study among postmenopausal women aged 50-74 years in Sweden, including 709 incident cases with histopathologically verified endometrial cancer and 3368 controls. RESULTS: Compared to lean women (recent body mass index (BMI), i.e. kg/m2 below 22.5), overweight women (recent BMI 28-29.99) had a 50% increase in risk for endometrial cancer (OR 1.5, 95% CI 1.0-2.1). Obese women (recent BMI 30-33.99) had a 3-fold increased risk (OR 2.9, 95% CI 2.0-4.0), and markedly obese women (recent BMI > or = 34) a 6-fold increased risk (OR 6.3, 95% CI 4.2-9.5). The OR for Type 2 diabetes mellitus was 1.5 (95% CI 1.0-2.1) and for Type 1 diabetes mellitus it was 13.3 (3.1-56.4). The effect of recent BMI was similar for tumors having different degrees of differentiation and myometrial invasion, and did not vary with age, time since menopause, smoking status, diabetes mellitus, and use of contraceptives. Hypertension increased risk only among obese women. BMI at age 18, height, and adult weight change were not independent risk factors. CONCLUSIONS: Recent overweight/obesity and diabetes mellitus (Types 1 and 2) are associated with endometrial cancer risk. Hypertension increases risk among obese women.

Adolescent↗

Clinical lacunar syndromes as predictors of lacunar infarcts. A comparison of acute clinical lacunar syndromes and findings on diffusion-weighted MRI.

OBJECTIVES: To evaluate if patients with acute lacunar syndromes have acute lacunar infarcts or other types of cerebral lesions on diffusion-weighted MRI. METHODS: Patients with acute lacunar syndromes underwent echo-planar diffusion MRI of the brain within 3 days after stroke onset. Localization and size of lesions with hyperintense signal were determined, compared with clinical characteristics and with findings on follow-up T2-weighted MRI. RESULTS: Twenty-three patients participated in the study. Thirteen patients had pure motor stroke, 1 pure sensory stroke, 8 sensorimotor stroke, and 1 ataxic hemiparesis. Twenty-two patients had at least one lesion with increased signal on diffusion-weighted MR images. These acute lesions were in the internal capsule/ basal ganglia/thalamus in 13 patients, subcortical white matter in 5 patients, brainstem in 2 patients, cortex (multiple small lesions) in 1 patient, and cortex + basal ganglia in 1 patient. The median volume of the lesions was 0.6 ml on the initial examination and on follow-up, of 17 patients after 1 to 5 months, 0.5 ml. CONCLUSIONS: Almost all patients with acute ischemic lacunar syndromes have acute lesions on echo-planar diffusion-weighted MRI within 3 days after stroke onset. These lesions are mostly small and subcortical, compatible with lacunar infarcts caused by single penetrating artery occlusion, but in a minor proportion of patients (2 of 23 in our study) a cortical involvement is found.

Acute Disease↗

Direct heterogeneous electron transfer of recombinant horseradish peroxidases on gold.

Clean polycrystalline gold electrodes were modified with native glycosylated horseradish peroxidases (HRP) or two different recombinant (carbohydrate free) HRPs; recombinant wild-type HRP (rec-HRP) and recombinant HRP containing a six histidine-tag at the C-terminus of the polypeptide chain (rec-HRP-His), respectively. Only the electrodes modified with the recombinant HRPs exhibited high current responses to H2O2 due to relatively rapid direct electron transfer (ET) between recombinant HRP and gold. The absence of a carbohydrate shell on rec-HRP and the additionally existing histidine-tag on rec-HRP-His improved the electrode sensitivity to H2O2 by more than 100 times if compared with the response observed at gold modified with native HRP. Rotating disk electrode experiments indicated that the heterogeneous electron transfer rates are equal to 4.7 and 7.5 s-1 for direct electron transfer between the gold electrode and rec-HRP or rec-HRP-His, respectively.

Electrochemistry↗

Electrochemical investigation of cellobiose oxidation by cellobiose dehydrogenase in the presence of cytochrome c as mediator.

An important aspect of the cytochrome c electrochemistry is the possibility of coupling the 'heterogeneous reactions' with other redox enzymes. Cellobiose dehydrogenase, a 89170 Da glycoprotein that contains both FAD and a b-type haem as prosthetic groups, donates electrons to a number of acceptors, including cytochrome c. While haem b is surrounded mainly by acidic amino acids, cytochrome c displays positive charged lysine groups around the haem site. Thus a fast reaction between both proteins is explicable. In the presence of cellobiose, a catalytic current was observed, owing to the interaction of cellobiose dehydrogenase with electrostatically adsorbed cytochrome c. Adsorption of cytochrome c provides a technological model surface for vectorial electron transfer.

Carbohydrate Dehydrogenases↗

Decreasing incidence of both major histologic subtypes of gastric adenocarcinoma--a population-based study in Sweden.

While the overall incidence of gastric cancer has fallen, presumably to a large extent in parallel with Helicobacter pylori infection, the occurrence of the diffuse histologic type is thought to have remained more stable, questioning the aetiologic role of H. pylori. We have analysed the incidence of the intestinal and diffuse types separately, while considering subsite (cardia/non-cardia). With an extensive prospective effort we identified all incident cases of gastric adenocarcinoma (n = 1337) in a well-defined Swedish population (1.3 million) 1989-1994. Tumours were uniformly classified histologically and topographically. Subgroup-specific incidence rates were computed and modelled using multivariate logistic regression. Site-specific trends were clearly discrepant. The overall incidence of adenocarcinoma distal to the gastric cardia declined by 9% (95% confidence interval 6-12%) per year, while cardia cancer remained stable. Thus, the feared rise in cardia cancer could not be confirmed despite clear site-specific trend discrepancies. The intestinal type predominated, especially in high-risk areas, while diffuse tumours prevailed among young patients and women. Both main histologic types of gastric adenocarcinoma declined markedly, at similar rapidity, and with no significant trend differences between the intestinal and diffuse types, even after multivariate adjustments. Our results are consistent with an aetiologic role of environmental factors including H. pylori also for diffuse-type gastric cancers.

Adenocarcinoma↗

Local breast cancer recurrence caused by mammographically guided punctures.

PURPOSE: To evaluate the risk of needle track seeding or tumor cell implantation as the cause of locally recurrent breast cancer after breast conserving surgery. MATERIAL AND METHODS: We reviewed recurrences from a consecutive series of 303 clinically nonpalpable breast cancers treated with breast conserving surgery after pre-operative localization. The median mammographic follow-up was 5.4 years. The suspicion of seeding or implantation was based on the location of the recurrent lesion in comparison with the needle path in two orthogonal mammographic projections. Pre-operative percutaneous biopsies had been done in 71% (214/303) of the cases. Postoperative radiotherapy was administered to 82% (194/238) of the invasive cancers and to 28% (18/65) of the ductal cancers in situ (DCIS). RESULTS: Locally recurrent cancer occurred in 11% (33/303) of the cases. Radiotherapy demonstrated a protective effect from relapse among invasive cancers but not for DCIS. Seeding or implantation was suspected in 3 recurrent invasive cancers which had not been subject to radiotherapy. The histopathological diagnosis of the primary cancer and the recurrent cancer were the same in these cases: adenoid cystic, mucinous and tubuloductal cancer. CONCLUSION: Seeding or implantation was suspected as the cause of local recurrence in 7% (3/44) of the invasive cancers which did not receive radiotherapy.

Adenocarcinoma↗

Platelet retention in coronary artery bypass surgery with and without a heart-lung machine. Cause of thrombosis in coronary artery bypass surgery.

The aim of this study was to examine platelet function after coronary artery bypass grafting (CABG) with and without the use of extracorporeal circulation (ECC). Sixteen male patients scheduled for CABG with (n = 8) and without (n = 8) ECC were included in the study. Platelet retention, as measured with a glass-bead retention test, was examined daily during the first postoperative week. Von Willebrand factor (vWF), ristocetin co-factor (Rcof) and prothrombin fragment (PF 1 + 2) were analyzed the day after the operation. We found a significant increase (p < 0.0001) in platelet retention during the first postoperative week after CABG. There was a tendency (not statistically significant) towards a more pronounced increase in the group operated on without ECC. This increase occurred despite the fact that all patients were treated with aspirin (75 mg daily) from the first postoperative day. The median time to maximal postoperative platelet retention was 2 days. In 3 patients platelet retention increased to more than 6 times the basal level.

Adult↗

Impact of bile acid malabsorption on steatorrhoea and symptoms in patients with chronic diarrhoea.

OBJECTIVE: Bile acids are important for fat absorption. The relationship between bile acid malabsorption and steatorrhoea and gastrointestinal symptoms in patients with chronic diarrhoea has only been studied on a limited scale. DESIGN: Ninety-four patients referred for chronic diarrhoea were prospectively investigated with the 75SeHCAT test, a faecal fat excretion test and registration of symptoms in addition to the standard clinical work-up. METHODS: The correlation between the 75SeHCAT value and the faecal fat excretion was calculated for different groups of patients. Symptoms were registered in a questionnaire over a period of seven consecutive days. RESULTS: Forty-two patients had a 75SeHCAT value < 10%. Mild steatorrhoea was common in patients with non-organic bile acid malabsorption (50%) and in patients with functional diarrhoea (38%). There was no correlation between low 75SeHCAT values and steatorrhoea, although some patients with severe organic disease had a concomitant malabsorption of fat and of bile acids. In coeliac disease, severe steatorrhoea was common even in patients with high 75SeHCAT values. Patients with bile acid malabsorption had more frequent (P < 0.008) and looser (P= 0.0021) stools compared with patients with functional diarrhoea. There was no difference in abdominal pain, distension or flatulence. CONCLUSION: Mild steatorrhoea is common in both non-organic bile acid malabsorption and functional diarrhoea. The 75SeHCAT value cannot predict the risk of steatorrhoea. The high prevalence of bile acid malabsorption in patients with chronic diarrhoea and the absence of specific symptoms, except frequent and more liquid stools, indicates that the 75SeHCAT test should be performed early in the investigation of these patients.

Adult↗

Association of a lack of psychosocial resources and the risk of giving birth to small for gestational age infants: a stress hypothesis.

OBJECTIVE: To test the stress hypothesis that women who give birth to small for gestational age infants lack important psychosocial coping resources, such as a sufficient social network, social support and control in daily life. DESIGN: A prospective cohort study of nulliparous pregnant women. SETTING: Antenatal care units in the city of Malmö, Sweden. POPULATION: All women (n = 994) during a one year period (1991-1992) were invited, and 872 (87 x 7%) participated. This study was restricted to pregnancies resulting in singleton live birth (n = 826); 6 x 7% of infants were classified as small for their gestational age. METHODS: Self-administered questionnaires were given to all women at the time of their first antenatal visit. MAIN OUTCOME MEASURES: The classification of small for gestational age was based on a gender-specific intrauterine growth reference curve. Newborn babies were classified as being small for gestational age if their birthweight was > 2 SD below the mean weight for gestational age. RESULTS: Lack of psychosocial resources, such as social stability, social participation, emotional and instrumental support, all increased the likelihood of delivering an infant that was small for gestational age. The odds ratios when controlled for demographic background factors, lifestyle factors and anthropomorphic measures were: OR 1 x 7 (95% CI 0 x 9-3 x 3) for women with poor social stability; OR 2 x 2 (95% CI 1 x 1-4 x 4) for women with poor social participation; OR 2 x 6 (95% CI 1 x 2-5 x 7) for women with poor instrumental support; and OR 1 x 5 (95% CI 0 x 8-2 x 8) for women with poor emotional support. Simultaneous exposure to a poor total network index, as well as a poor total support index showed a significantly increased odds ratio for having a small for gestational age baby: OR 3 x 3 (95% CI 1 x 6-6 x 7) and OR 2 x 7 (95% CI 1 x 3-5 x 6), respectively. A synergy index of 9 x 0 and 6 x 8 supported the assumption of an interaction between immigrant status and poor total network or poor total support, in a synergistic direction. CONCLUSIONS: The findings support the stress-hypothesis that a lack of psychosocial resources might increase the risk of giving birth to a baby that is small for gestational age.

Adaptation, Psychological↗