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Biomedical subjects

I Andersson

Publications and source records attributed to I Andersson.

At least 37 records · Page 2Linked to original sources

Towards new beta-lactam antibiotics.

Antibiotics have had a profound impact on human health and belong to one of the largest-selling classes of drugs worldwide. Introduced into industrial production only some half century ago, these miracle drugs have been the main contributors to the recent increase in human life expectancy. However, the accelerated emergence of bacteria that are resistant to multiple antibiotic types now appears as the most serious threat to continuing success in the treatment of infectious diseases. Recent advances in our knowledge of the structures and mechanisms of enzymes in the biosynthetic pathways of penicillins and cephalosporins, amongst the most important antibiotics in current use, have identified a common structural core together with common iron- and cosubstrate-binding motifs. The diversity in the catalytic specificities of these oxygenases using very similar structural platforms suggests that altering the substrate and product specificities of these enzymes should be possible in the laboratory. This opens up new avenues for industrial production and medical utilisation.

Anti-Bacterial Agents↗

Long-term studies on transfer of 137Cs from soil to vegetation and to grazing lambs in a mountain area in northern Sweden.

Studies were made during 1990-1997 on the transfer of 137Cs from soil to vegetation (herbage) and to grazing lambs on a mountain farm with an uncultivated grazing area of about 10 km2. The farm is situated in an area in Northern Sweden which was contaminated by the Chernobyl fallout in 1986. The mean concentration of 137Cs in the soil to a depth of 10 cm for eight sampling sites observed in the 8-year period was 14.51 kBq/m2, while in the cut herbage the average concentration was 859 Bq/kg d.w. and in lamb meat 682 Bq/kg w.w. A slow vertical migration of 137Cs in the 0-10 cm soil layer was indicated. Although the 137Cs concentration in herbage gradually decreased, the concentration in lamb meat varied from year to year. Soil ingestion by the lambs as a pathway for activity transfer was shown to be negligible, while ingestion of fungi with high concentrations of 137Cs was demonstrated to occur, as large numbers of fungi spores were counted in samples of the lambs' faeces. Fungi ingestion might therefore partly explain the varying mean yearly 137Cs concentrations in lamb muscle. The mean transfer parameters were as follows: for "soil to herbage" 61.3 Bq/kg d.w. herbage per kBq/m2 soil, for "herbage to lamb meat" 0.81 Bq/kg w.w. meat per Bq/kg d.w. herbage, and for "soil to lamb meat" 47.1 Bq/kg w.w. meat per kBq/m2 soil. A trend of decreasing values of the transfer parameter for "soil to herbage" indicated that 137Cs was becoming less available for root-uptake with time. The effective ecological half-life of 137Cs in soil, herbage and lamb meat was calculated to be 19, 7 and 16 years, respectively. It can be concluded that natural areas are vulnerable to 137Cs contamination, resulting in high concentrations in plants, fungi and lamb meat for a long time.

Animals↗

Intake of sweet foods and counts of cariogenic microorganisms in obese and normal-weight women.

OBJECTIVE: To study the intake of sweet foods in obese and normal-weight women, while also taking menstrual cycle effects on eating behaviour into consideration. An objective test of the intake of sugar-containing foods was introduced by measuring salivary counts of mutans streptococci and lactobacilli. DESIGN: A cross-sectional comparison of the intake of sweet foods in obese and normal-weight women. The obese women were also studied longitudinally after 10 weeks in a weight reduction programme. SUBJECTS: Obese (n=72, body mass index (BMI) 42.0+/-5.2 kg/m2) and normal-weight women (n=67, BMI 22.2+/-1.6 kg/m2) participated. RESULTS: Mutans streptococci in saliva were higher in obese than in normal-weight women (P<0.0001), although the reported habitual daily intake of sweet foods did not differ. Of the menstruating women, 80% of the obese subjects and 62% of the normal-weight ones (P<0.05) reported periods during the menstrual cycle with an 'extra large' intake of sweet foods; these intakes were higher in obese than in normal-weight women (P<0.01). The obese women reduced their intake of sweet foods after 10 weeks of weight reduction, although these changes were not pronounced enough to significantly affect the counts of cariogenic microorganisms. CONCLUSIONS: In contrast to most previous cross-sectional studies, this study shows that obese women have a higher intake of sweet foods, especially pre-menstrually. This was indicated by higher salivary counts of cariogenic microorganisms. SPONSORSHIP: Karolinska Institute Research Funds.

Adult↗

Night eating and nocturnal eating-two different or similar syndromes among obese patients?

OBJECTIVE: The main aim of this study was to identify subjects with (1) night eating syndrome (defined as morning anorexia, evening hyperphagia and insomnia) and (2) nocturnal eating syndrome (defined as eating at night after having gone to bed). In the literature the differences and similarities between these two syndromes are not clear. SUBJECTS: One-hundred and ninety-four obese patients from an academic, clinical obesity unit. Mean BMI (+/-s.d.) was 40+/-5 kg/m2, age 44+/-12 y and 76% were women. MEASUREMENTS: Questionnaires with multiple choices and open questions along with the Binge Eating Scale. RESULTS: Fourteen percent of the patients met the criteria for night eating and/or nocturnal eating syndrome. Night eating syndrome was manifest in 6% of the patients and nocturnal eating syndrome in 10%. Both the night eaters and the nocturnal eaters had more trouble getting to sleep than the patients without night/nocturnal eating problems (P<0.001 and P<0.01). The nocturnal eaters also had more trouble staying asleep (P<0.001). Morning anorexia was not typically found in nocturnal eaters. Being on long-term sick leave was more common among the nocturnal eaters (P<0.01). CONCLUSION: Fourteen percent of the patients at our obesity unit met the criteria for night eating and/or nocturnal eating syndrome. There are clear similarities between night eating syndrome and nocturnal eating syndrome, but also differences.

Adult↗

Case studies of food shopping, cooking and eating habits in older women with Parkinson's disease.

AIMS: The principal aim of this study was to investigate how married and single-living older women diagnosed with Parkinson's disease managed to shop for food, cook and carry out their meals; and to observe whether their nutritional needs were satisfied. A secondary aim was to identify women with severe motor problems and describe their food-related situation. BACKGROUND: Parkinson's disease is associated with motor and eating problems, which, combined with age-related declines in physical functioning, may affect activities of daily living and dietary intake. METHODS: Qualitative interviews and food survey were carried out in the homes of 10 women aged 67-80 years. The sample was recruited from outpatient registers. RESULTS: Decreased sense of smell, appetite and taste in combination with problems transporting food to the mouth and swallowing were risks for nutritional well-being. Food shopping was most difficult to manage, but six cooked even if their cooking style was changed. Married women with healthy husbands received support from their spouses. Single-living women suffering from motor problems had to call for help, which represented a threat to their well-being. Independence was given high priority. CONCLUSIONS: The whole situation - including psychosocial and stress factors - must be taken into account when discussing shopping, cooking and eating among old women with Parkinson's disease. A home-helper should not take over but facilitate procedures so that the woman can manage as long as possible. This gave them self-esteem.

Activities of Daily Living↗

Nonattendance in mammographic screening: a study of intraurban differences in Malmö, Sweden, 1990-1994.

Mammographic screening may reduce breast cancer mortality. Not all women, however, come for examination. The objective in this study from Malmö has been to assess extent to which the rate of nonattendance varies between residential areas with different sociodemographic profiles. The study is based on 32,605 women, 45 to 68 years old and living in 17 areas, who between 1990 and 1994 were invited to screening. Between age groups, the age-specific nonattendance rate ranged from 31% to 35 % (P < .01). The nonattendance rate was highest for women 65 years or older. Between residential areas, age-adjusted nonattendance rates ranged from 23% to 43% (P < .01). A socioeconomic score was developed to express the socioeconomic circumstances in the residential areas and ranged from -7.18 in the most deprived area to 5.01 in the least. Nonattendance covaried in an inverse fashion with the socioeconomic score (r = -0.78; P < .01). One of three women in this urban population did not accept the invitation to mammographic screening. Our conclusion is that women in areas with less favorable circumstances seem to be less willing to participate.

Aged↗

Speciation in the vanadate-alanylhistidine-peroxide system.

The speciation in the quaternary aqueous H+-H2VO4(-)-H2O2-L-alpha-alanyl-L-histidine (Ah) system has been determined from quantitative 51V NMR measurements and potentiometric data (glass electrode). The study was performed in 0.150 M Na(Cl) medium at 25 degrees C. Data were evaluated with the computer program LAKE, which is able to treat combined potentiometric and NMR data. In the ternary H+-H2VO4(-)-Ah system, two complexes, (H+)p(H2VO4-)q(Ah)r, having (p, q, r) values (0, 1, 1) and (1, 1, 1) (pKa = 6.88) explain all data. In the quaternary H+-H2VO4(-)-H2O2-Ah system, seven complexes were determined in addition to all binary and ternary complexes, four with a V/X/Ah ratio 1:1:1 and three with a ratio 1:2:1 (X = peroxo ligand). VX2Ah2- and VX2Ah- (pKa = 8.26) are the main quaternary complexes and predominate in the pH range 5 to 9. Chemical shifts, compositions and formation constants for all the quaternary complexes are given, and equilibrium conditions are illustrated in distribution diagrams.

Alanine↗

Speciation in vanadium bioinorganic systems. 6. Speciation study of aqueous peroxovanadates, including complexes with imidazole.

Using a combination of potentiometry (glass electrode) and quantitative 51V NMR spectroscopy, the full speciation in the vanadate-peroxide and vanadate-peroxide-imidazole systems was determined in the pH range 1-10 (0.150 M Na(Cl) medium, 25 degrees C). Using the computer program LAKE, the pKa value of imidazole and the formation constants for 10 peroxovanadate species and also for three more species where a single imidazole moiety is also bound, have been calculated. The experimental data show a good fit to the calculated speciation model, even for the less abundant species. The species are either monomeric or dimeric in vanadium, and four resonances of the dimeric species have been unambiguously assigned via 2D 51V NMR. Diperoxovanadates are the favoured species at pH 2-10, when sufficient peroxide is present. Imidazole is found to bind strongly to them at pH 6-9. The equilibrium conditions are illustrated in distribution diagrams.

Hydrogen Peroxide↗

Meal pattern and risk factor evaluation in one-year completers of a weight reduction program for obese men - the 'Gustaf' study.

OBJECTIVES: To evaluate changes in meal patterns and in obesity related risk factors after 1 year of treatment in obese men. DESIGN: Data from two 24-h dietary recalls, performed at base-line and after 1 year of treatment, were related to changes in medical risk factors. SETTING: Academic obesity unit. SUBJECTS: Sixty-three men, aged 44 (eight) years (mean [SD]) and Base-line Body Mass Index (BMI) 37.4 (4.6) kg m-2, who had completed 1 year of treatment. The men were subdivided by tertiles according to weight change: tertile I (n = 21), mean +0.3 kg, tertile II (n = 21), mean -5.8 kg and tertile III (n = 21), mean -14.2 kg. MAIN OUTCOME MEASURES: Weight loss, changes in meal patterns and in obesity related medical risk factors. RESULTS: The reported mean energy intake decreased after treatment in tertiles II and III by 700 (1300) kcal (P < 0.05) and 700 (900) kcal (P = 0.001), respectively. In tertile III the energy-% from fat decreased (P < 0.05) with a reciprocal increase in energy-% from protein (P < 0.05). The frequency of snacks of a low nutritional quality decreased (P < 0.01) in tertile III together with an increase in energy-% from 'hot meals of good quality' (P < 0.05). Obesity related risk factors (anthropometry, blood pressure, serum lipid concentrations, blood glucose and plasma insulin) improved in a beneficial way only in tertile III. CONCLUSIONS: The weight loss in the successful tertile III men was to a great extent explained by fewer low quality snacks but more energy from high quality meals. These changes reflected the behaviour modification strategy recommended.

Adult↗

Associations of leptin, insulin resistance and thyroid function with long-term weight loss in dieting obese men.

OBJECTIVE: The aim of the present study was to identify predictors of weight loss in obese men participating in a 2-year behaviour modification programme. DESIGN: Longitudinal, clinical intervention study of a behaviour modifying weight loss program. SETTING: University Hospital, Stockholm, Sweden. SUBJECTS: Forty-four obese men (age, 42.7 +/- 1.1 years: BMI, 37.1 +/- 0.6 kg m(-2), mean +/- SEM) followed for 2 years. INTERVENTIONS: Behaviour modification weight loss programme. MAIN OUTCOME MEASURES: Associations between plasma leptin and thyroid function tests, insulin resistance by homeostatic model assessment (HOMA), dietary recall and anthropometrically determined body composition. RESULTS: At baseline, there were significant correlations between plasma leptin and body mass index (BMI), fat-free mass (FFM) and insulin resistance. Median weight loss over 2 years was 4.9 kg (range, -27.2 to +11.9). Baseline serum leptin concentrations adjusted for BMI (leptin/BMI ratio) were significantly correlated with 2-year weight change (r = 0.34, P = 0.04). A subset of seven of the 44 men gained weight over the 2 years. These 'gainers' differed significantly in initial leptin/BMI ratio (0.62 +/- 0.07) compared with the 37 'losers' (0.42 +/- 0.03, P < 0.05). In a multiple regression model, baseline leptin, insulin and age predicted 22% of the variance in weight change with no additional significant contribution from BMI, FFM, waist:hip ratio, thyroid function tests or energy intake. There was a strong correlation between the change in leptin concentrations and the change in insulin resistance from baseline to 2-year follow-up (r = 0.54; P < 0.001). CONCLUSION: Baseline plasma leptin concentrations predicted long-term weight loss. Inappropriate leptin secretion or disposal, corrected for BMI, was associated with failure to maintain weight loss in obese men in a behaviour modification weight loss programme.

Adult↗

Mammographic screening under age 50: a review.

Trials indicate that screening women between 40 and 49 with mammography results in a clear mortality benefit. Whether this is worth the side-effects and financial cost is a matter of judgement. Some national health authorities and several other bodies consider the balance favourable enough to recommend general screening for this age group.

Journal Article↗

Survival of women with breast cancer in relation to smoking.

OBJECTIVE: To compare survival of patients with breast cancer who had never smoked, were smokers, and who were ex-smokers. DESIGN: Observational study. SETTING: City of Malmö, Sweden. PATIENTS: 792 patients with breast cancer diagnosed between 1977-1986 in the Malmö mammographic screening trial. INTERVENTIONS: Follow-up of breast cancer cases through record-linkage with the Swedish Cause of Death Registry. MAIN OUTCOME MEASURES: Death from breast cancer. Relative risk (RR) with 95% confidence interval (CI) of death from breast cancer was calculated for different smoking groups using Cox's proportional hazards analysis. RESULTS: During a mean follow-up of 12.1 years, 145 patients died of breast cancer. Breast cancer mortality was 1347/10(5) person-years in those who had never smoked, 1941/10(5) in smokers, and 1493/10(5) in ex-smokers. The crude RR for smokers and ex-smokers, compared with those who had never smoked were 1.44 (1.01 to 2.06) and 1.13 (0.66 to 1.94), respectively. The RR associated with smoking remained significant after adjustment for age and stage at diagnosis, 2.14 (1.47 to 3.10), and other potential confounders. CONCLUSIONS: Survival after breast cancer was, as expected, strongly related to stage at diagnosis. However, stage by stage there was considerable variation between individual patients. We conclude that differences with regard to exposure to smoking contribute to this heterogeneity.

Adenocarcinoma↗

Implementation of service screening with mammography in Sweden: from pilot study to nationwide programme.

Establishment of mammography screening in Sweden has progressed logically from pilot study through clinical trials to service screening. Screening with mammography for early detection of breast cancer has been provided by all Sweden's 26 county councils since 1997. It took 23 years from the initial pilot study through clinical trials to the establishment of mammography service screening throughout Sweden. In the screening rounds completed by 1995-96, and provided by all but one county council, 1040000 women participated, corresponding to 81% of those invited. The national average recall rate was 2.2%, and consequently 23000 women were recalled for additional investigations. Eleven county councils invited women aged 40-74, six invited women aged 50-69, the remaining eight invited women between both these age intervals. Mammography outside screening programmes-clinical mammography-is available throughout Sweden. About 100000 women a year were referred for clinical mammography and about 50% of these were either younger or older than those invited for screening. A negative relation between the use of clinical mammography and participation in the screening programmes was noticed.

Adult↗

Studies on the active site of deacetoxycephalosporin C synthase.

The Fe(II) and 2-oxoglutarate-dependent dioxygenase deacetoxycephalosporin C synthase (DAOCS) from Streptomyces clavuligerus was expressed at ca 25 % of total soluble protein in Escherichia coli and purified by an efficient large-scale procedure. Purified protein catalysed the conversions of penicillins N and G to deacetoxycephems. Gel filtration and light scattering studies showed that in solution monomeric apo-DAOCS is in equilibrium with a trimeric form from which it crystallizes. DAOCS was crystallized +/-Fe(II) and/or 2-oxoglutarate using the hanging drop method. Crystals diffracted to beyond 1.3 A resolution and belonged to the R3 space group (unit cell dimensions: a=b=106.4 A, c=71.2 A; alpha=beta=90 degrees, gamma=120 degrees (in the hexagonal setting)). Despite the structure revealing that Met180 is located close to the reactive oxidizing centre of DAOCS, there was no functional difference between the wild-type and selenomethionine derivatives. X-ray absorption spectroscopic studies in solution generally supported the iron co-ordination chemistry defined by the crystal structures. The Fe K-edge positions of 7121.2 and 7121.4 eV for DAOCS alone and with 2-oxoglutarate were both consistent with the presence of Fe(II). For Fe(II) in DAOCS the best fit to the Extended X-ray Absorption Fine Structure (EXAFS) associated with the Fe K-edge was found with two His imidazolate groups at 1.96 A, three nitrogen or oxygen atoms at 2.11 A and one other light atom at 2.04 A. For the Fe(II) in the DAOCS-2-oxoglutarate complex the EXAFS spectrum was successfully interpreted by backscattering from two His residues (Fe-N at 1.99 A), a bidentate O,O-co-ordinated 2-oxoglutarate with Fe-O distances of 2.08 A, another O atom at 2.08 A and one at 2.03 A. Analysis of the X-ray crystal structural data suggests a binding mode for the penicillin N substrate and possible roles for the C terminus in stabilising the enzyme and ordering the reaction mechanism.

Binding Sites↗

Food-based classification of eating episodes (FBCE).

The concept for categorization of eating episodes in dietary surveys was originally developed in studies of shift workers to compare "meal patterns" between night and day work shifts. The concept has been further improved through experience from applications in dietary surveys in other populations. In this paper, results from categorization of eating episodes in shift workers, elderly women and men during life transition periods, elderly female leg ulcer patients and obese men and their lean controls are shown and discussed. The categorization concept is based on seven food categories with food items of similar nutrient characteristics within each category. Each eating event is categorized as any of four types of "meals" or four types of "snacks" due to its combination of food categories. Thus, categorization is based on visible properties (food types) but at the same time reflecting invisible properties (nutrients). Criteria is also established to sub-categorize the "meal" types as being either "prepared" or "quick-prepared" from a behavioural perspective. Use of a defined and reliable concept for categorization is necessary to study eating episodes in dietary surveys, their determinants and also consequences on health and performance. Nocturnal eating during the circadian nadir might affect nutritional status. Since increasingly western populations appear to be moving from regular and planned meals to more episodic eating "around the clock", such analyses are of increasing interest in a bio-social perspective.

Adult↗

Summary report of the TD-3 workshop: characterization of 83 antibodies against prostate-specific antigen.

Twelve research groups participated in the ISOBM TD-3 Workshop in which the reactivity and specificity of 83 antibodies against prostate-specific antigen (PSA) were investigated. Using a variety of techniques including cross-inhibition assays, Western blotting, BIAcore, immunoradiometric assays and immunohistochemistry, the antibodies were categorized into six major groups which formed the basis for mapping onto two- and three-dimensional (2-D and 3-D) models of PSA. The overall findings of the TD-3 Workshop are summarized in this report. In agreement with all participating groups, three main antigenic domains were identified: free PSA-specific epitopes located in or close to amino acids 86-91; discontinuous epitopes specific for PSA without human kallikrein (hK2) cross-reactivity located at or close to amino acids 158-163; and continuous or linear epitopes shared between PSA and hK2 located close to amino acids 3-11. In addition, several minor and partly overlapping domains were also identified. Clearly, the characterization of antibodies from this workshop and the location of their epitopes on the 3-D model of PSA illustrate the importance of selecting appropriate antibody pairs for use in immunoassays. It is hoped that these findings and the epitope nomenclature described in this TD-3 Workshop are used as a standard for future evaluation of anti-PSA antibodies.

Antibodies, Monoclonal↗

Characterization of antibodies to prostate-specific antigen.

Antibodies submitted to the ISOBM TD-3 PSA Workshop were tested for reactivity with free prostate-specific antigen (PSA) and the PSA alpha1-antichymotrypsin (ACT) complex, inhibition of proteolytic activity, recognition of continuous epitopes, and epitope specificity based on complete cross-inhibition studies. The antibodies could be separated into two categories: those recognizing hidden epitopes specific for free PSA, and those recognizing epitopes in both free PSA and the PSA-ACT complex. A large number of distinct antigenic domains were identified both in free PSA and the PSA-ACT complex.

Antibodies, Monoclonal↗

Structure of a cephalosporin synthase.

Penicillins and cephalosporins are among the most widely used therapeutic agents. These antibiotics are produced from fermentation-derived materials as their chemical synthesis is not commercially viable. Unconventional steps in their biosynthesis are catalysed by Fe(II)-dependent oxidases/oxygenases; isopenicillin N synthase (IPNS) creates in one step the bicyclic nucleus of penicillins, and deacetoxycephalosporin C synthase (DAOCS) catalyses the expansion of the penicillin nucleus into the nucleus of cephalosporins. Both enzymes use dioxygen-derived ferryl intermediates in catalysis but, in contrast to IPNS, the ferryl form of DAOCS is produced by the oxidative splitting of a co-substrate, 2-oxoglutarate (alpha-ketoglutarate). This route of controlled ferryl formation and reaction is common to many mononuclear ferrous enzymes, which participate in a broader range of reactions than their well-characterized counterparts, the haem enzymes. Here we report the first crystal structure of a 2-oxoacid-dependent oxygenase. High-resolution structures for apo-DAOCS, the enzyme complexed with Fe(II), and with Fe(II) and 2-oxoglutarate, were obtained from merohedrally twinned crystals. Using a model based on these structures, we propose a mechanism for ferryl formation.

Cloning, Molecular↗