Biomedical subjects

B Nilsson

Publications and source records attributed to B Nilsson.

At least 235 records · Page 13Linked to original sources

PubMed1993

An improved strategy for determining resonance assignments for isotopically enriched proteins and its application to an engineered domain of staphylococcal protein A.

Sequence-specific resonance assignments provide the basis for interpreting multidimensional NMR spectra and for determining 3D structures of proteins from these data. We have developed an improved strategy for determining these sequence-specific NMR assignments in small proteins and applied this method in determining proton and nitrogen resonance assignments for an 8.2-kDa engineered domain (the Z-domain) of the cell wall protein A of Staphylococcus aureus. First, HCCNH-TOCSY [Lyons, B. A. & Montelione, G.T. (1993) J. Magn. Reson. 101B, 206] data were used together with 2D 2QF-COSY, TOCSY, and 15N-HSQC data to identify amino acid spin systems. Most asparagine and glutamine spin systems were also identified uniquely from these triple-resonance data. Next, complementary HCC(CO)-NH-TOCSY [Montelione, G. T., et al. (1992) J. Am. Chem. Soc. 114, 10975] data were used to identify sequential connections from the aliphatic H alpha, H beta, H gamma, H delta, and H epsilon resonances of residue i to the amide and nitrogen resonances of residue i + 1. By combined analysis of HCCNH-TOCSY and HCC(CO)NH-TOCSY spectra we have determined most of the proton and nitrogen resonance assignments for the Z-domain. This represents the first example of the use of this triple-resonance technique to determine extensive resonance assignments in a small protein.

Amino Acid Sequence↗

PubMed1993

An improved approach to the analysis of the structure of small oligosaccharides of glycoproteins: application to the O-linked oligosaccharides from human glycophorin A.

Treatment of purified human glycophorin A with alkaline borohydride cleaved the oligosaccharide side chains to yield alditol derivatives that were separated by gel filtration into three mixtures of low molecular weight compounds. Each mixture was oxidised with periodate, and the products were reduced with borohydride and analysed after acetylation or methylation by GLC-MS and FABMS. The resulting data allowed the monosaccharide sequence and linkage positions to be assigned to each component of the mixtures. The anomeric configuration was determined by 1H NMR spectroscopy of the intact fractions. The structures of a desialylated tetrasaccharide, two monosialylated trisaccharides, and five other minor products were defined.

Acetylation↗

PubMed1993

Treatment failure and dietary habits in women with breast cancer.

BACKGROUND: Epidemiological and experimental evidence suggests that breast cancer risk can be reduced by dietary measures. Study of the relationships between dietary habits and prognosis in patients with breast cancer is essential to the design of diet intervention trials. PURPOSE: Our purpose was to determine whether dietary habits are associated with disease-free survival in patients with breast cancer who have undergone treatment. METHODS: We interviewed 240 women about their dietary histories. These women were 50-65 years old and had pathological stage I-II breast cancer with subsequent follow-up for 4 years; 209 of these women were postmenopausal. Differences in dietary variables between groups of patients were analyzed with bivariate and multivariate statistical methods. RESULTS: Cancers were classified as estrogen receptor (ER) rich (> or = 0.10 fmol/micrograms of DNA) in 149 patients and as ER poor (< 0.10 fmol/micrograms of DNA) in 71 patients. Fifty-two patients had treatment failure during follow-up. The 30 patients with ER-rich tumors who had treatment failure reported higher intakes of total fat, saturated fatty acids, and polyunsaturated fatty acids than did the 119 patients with ER-rich tumors who did not have treatment failure. The multiple-odds ratio (OR) for treatment failure in these women was 1.08 for each 1% increment in percentage of total energy (E%) from total fat. For treatment failure within the first 2 years, the OR was 1.19 for each 1-mg increase in vitamin E intake per 10 megajoules of energy. In women with treatment failure 2-4 years after diagnosis, ORs were 1.13 and 1.23 for each E% increment in total fat or saturated fatty acids, respectively. No association between dietary habits and treatment failure was found for women with ER-poor cancers. There was a tendency to a dose-response relationship (in quartiles) between intake of saturated fatty acids and disease-free survival, but the observed differences were not statistically significant. CONCLUSIONS: Dietary habits at the time of diagnosis may affect prognosis, at least for patients with ER-rich breast cancers. Dietary fat may have an effect on growth or spread of breast cancer, both of which may vary according to type of fat. Total fat and saturated fatty acids were the dietary parameters most strongly associated with risk for treatment failure. IMPLICATIONS: Dietary intervention might serve as an adjuvant treatment to improve breast cancer prognosis.

Aged↗

PubMed1993

Autografting in chronic myelogenous leukemia followed by immunotherapy.

Patients with chronic myelogenous leukemia (CML) can be cured with allogeneic bone marrow transplantation. Over the past decade, it has become clear that immunological mechanisms, in the form of graft-versus-leukemia, constitute an integral part of this therapy. Because of limitations imposed by a lack of suitable donors, age, and toxicity, only a minority of patients can be offered allogeneic bone marrow transplantation (BMT). Recently, attempts have been made to employ autologous bone marrow transplantation (ABMT) for the therapy of CML using a variety of pre- and post-transplantation manipulations. This report describes the rationale for an ongoing clinical trial using the immunomodulator roquinimex (Linomide), following autologous bone marrow transplantation, in an attempt to stimulate the immunological responses thought to be critical for successful therapy in CML.

Adjuvants, Immunologic↗

PubMed1993

Investigation of the structural heterogeneity in the carbohydrate portion of a mouse monoclonal immunoglobulin A antibody.

A mouse immunoglobulin A monoclonal antibody was isolated from hybridoma culture fluid by affinity chromatography. Chemical analysis of the intact antibody showed a monosaccharide composition, which besides mannose also contained monosaccharides commonly found in N-linked complex type of carbohydrate structures. No N-acetylgalactosamine was found showing the absence of O-linked oligosaccharides. The carbohydrate chains were released from the polypeptide and after fractionation on immobilized concanavalin A and high-performance ion-exchange chromatography structural analysis was performed. The structures were determined by chemical analyses, periodate oxidation in combination with fast atom bombardment mass spectrometry, and 500 MHz 1H NMR spectroscopy. The data revealed a great structural heterogeneity, including partially sialylated bi- and triantennary type of structures. Both types contained in addition species with branches terminated by Gal alpha 1-3Gal sequences.

Animals↗

PubMed1993

Carbohydrate antigen expression in murine embryonic stem cells and embryos. II. Sialylated antigens and glycolipid analysis.

A mouse embryonic stem (ES) cell line E14 and early mouse embryos were stained with a panel of 15 monoclonal antibodies recognizing sialylated or potentially sialylated carbohydrate determinants. Sialyl Le-x and sialyl Le-a were detected on the pre-implantation embryo from the 8-cell stage, and sialyl Le-a weakly on undifferentiated ES cells. Changes in cell surface carbohydrates occurred after induction of ES cell differentiation with retinoic acid (RA) and dibutyryl cAMP. Qualitative analysis of the neutral glycolipids of untreated and RA-treated ES cells using high-performance thin-layer chromatography (HPTLC) revealed few differences between the two types of culture. The major gangliosides in both cultures were indicative of an active 'a' ganglioside synthesis pathway. GD3, a precursor of the 'b' synthesis pathway, previously reported to be characteristic of embryonal carcinoma (EC) cells, was absent. RA-induced differentiation caused a shift in the spectrum to more complex gangliosides. Application of fast atom bombardment mass spectrometry (FAB-MS) to permethylated derivatives of individual bands permitted partial characterization of an unusual sialylated glycolipid and a rare ganglioside with the suggested structure of GalNAc-GD1a.

Animals↗

PubMed1993

Dietary habits and mammographic patterns in patients with breast cancer.

Between 1983 and 1986, dietary history interviews were conducted with 238 women aged 50-65 years who had surgery for stage I-II breast cancer. Diagnostic mammograms were coded in line with Wolfe's criteria in N1, P1, P2, and Dy patterns. Women with Dy pattern reported significantly higher intake of total fat, monounsaturated fatty acids (FA), polyunsaturated FA, n-3 FA, n-6 FA in per cent of energy (E%), and alpha-tocopherol in mg/10 MJ. Fat intake was lowest in women with N1 pattern and highest in those having Dy pattern. Patients having ER-rich cancers and Dy pattern reported significantly higher intake of total fat, monounsaturated FA, polyunsaturated FA, n-6 FA (E%), and alpha-tocopherol (mg/10 MJ), as well as significantly lower intake of carbohydrate (E%) and calcium (g/10 MJ). In the stepwise multivariate analysis, the multivariate-odds ratio (OR) for having P2 + Dy patterns was 1.06 (95% confidence interval (CI), 1.02-1.12) for each increment in E% of total fat. In women with ER-rich tumors this OR was 1.09 (95% CI, 1.02-1.16). The highest self-reported body mass index (BMI) was observed in women with N1 + P1 patterns. OR for having P2 + Dy patterns was 0.91 (95% CI, 0.83-0.98) for each increment in 1 kg/m2 of BMI. The results suggest that dietary habits affect the mammographic parenchymal pattern in women with breast cancer and that a high fat intake is associated with a higher proportion of mammograms with Dy pattern in such patients.

Aged↗

PubMed1993

Continuous versus intermittent prednimustine treatment of non-Hodgkin's lymphoma.

Seventy-eight patients with advanced non-Hodgkin's lymphomas were randomized for treatment with prednimustine (Sterecyt) in two different schedules: either receiving continuous treatment at a dosage of 60 mg daily, or intermittent two-week courses with 200 mg daily for five days. The aim of the study was to compare efficacy and side effects of the two different schedules. Forty patients received continuous, and 38 patients intermittent treatment. Objective response was achieved in 66% of 71 evaluable patients, equally distributed between the two treatment arms. The 10-year survival rate was 20% (SE = 6%; continuous treatment) and 11% (SE = 5%; intermittent treatment), respectively (logrank p = 0.26). Median time to response, duration of response and time to progression showed no significant difference between the treatment groups. Median time on treatment was longer for patients treated continuously, probably due to more easily performed dose adjustments in such patients. There was a significant decrease of the white blood cell counts in patients who received prednimustine continuously compared with those treated according to the intermittent schedule (p = 0.02). No significant differences were found regarding the thrombocyte levels. The response rate was closely related to haematological toxicity (p = 0.01). Our results suggest that prednimustine in non-Hodgkin's lymphomas has similar effectiveness both in daily treatment and in a two-weekly intermittent schedule. Continuously given treatment may be easier to govern and, thereby, allow for higher treatment intensity. With respect to toxicity, daily doses of approximately 30-40 mg in previously untreated patients may be recommended.

Adult↗

PubMed1993

Complement activation by polymethyl methacrylate minimized by end-point heparin attachment.

After intraocular lens implantation, despite good clinical results, many cataract patients develop a chronic uveitis, caused by an inflammatory response to the implant. One way to improve the biocompatibility of the intraocular lens is to modify the surface by end-point heparin attachment. This study shows that complement activation caused by poly(methyl methacrylate) can be diminished by end-point heparin attachment, as demonstrated by a significant reduction in the generation of C3a and fluid phase terminal complement complexes. It suggests that assessment of complement activation is a good indicator of the biocompatibility of intraocular lenses.

Biocompatible Materials↗

PubMed1993

The interaction between different domains of staphylococcal protein A and human polyclonal IgG, IgA, IgM and F(ab')2: separation of affinity from specificity.

Binding properties of staphylococcal protein A (SpA) to different human immunoglobulins have been investigated. In this analysis, intact SpA as well as SpA-derived fragments containing one to five IgG-binding domains of different compositions, were used. The affinity binding constants of the different proteins to human polyclonal IgG, IgA, IgM and F(ab')2-fragments as well as their binding capacity to the immunoglobulin molecules were determined. The results show that although all the proteins bound to IgG, regardless of size or composition, the binding strength differed significantly. Proteins containing five domains have a stronger affinity for IgG than those containing one or two. There were no marked differences in binding strength between different domains. However, the binding ability to IgA and IgM showed a marked difference between the various SpA-derived proteins of different compositions. This discrepancy was correlated to differences in their relative binding properties to isolated F(ab')2-fragments of IgG. Hence, we conclude that the binding affinity is mainly affected by the number of domains, whereas the binding specificity is to a large extent determined by which domains are selected.

Antibody Affinity↗

PubMed1993

Conformational epitopes of C3 reflecting its mode of binding to an artificial polymer surface.

The aim of the study was to investigate the incompletely understood mechanisms of complement (C) activation and binding on artificial biomaterials. Polystyrene in the form of microtitre plates was used as target for C binding, detectable by ELISA using monoclonal anti-C3 antibodies specific for conformational epitopes expressed by bound C3 and C3 fragments. C3 binding in whole blood/plasma/serum is maximal at low dilutions and occurs predominantly by C activation. At higher dilutions, C3 binding occurs at approximately 1/3 of maximal levels and is solely an effect of adsorption. C3 adsorption in the lower serum dilution range, occurs at low but clearly detectable levels. Comparative epitope analysis between C3 fragments, actively bound to polystyrene in the presence of serum, and of iC3b bound to sheep erythrocytes, clearly indicates that C3 binding/activation on polystyrene takes place as a C3 convertase-mediated reaction, which in serum/plasma is followed by a secondary factor I-dependent degradation of the bound C3b into iC3b. The neo-epitope analysis of serum-contacting polystyrene revealed that the adsorbed C3, throughout the entire serum dilution range tested, deposits in a state closely similar to that observed for purified C3 at a high packing density. Polystyrene surfaces with adsorbed purified C3 expressing this epitope profile were found to mediate APW dependent deposition of C3b in pig serum, presumably by forming a hybrid convertase with porcine Bb. These data therefore suggest that adsorbed C3 on serum-contacting polystyrene surfaces may initiate complement activation via the APW.

Adsorption↗

PubMed1993

Interactions of drugs acting against Staphylococcus aureus in vitro and in a mouse model.

Two combinations of antibiotics, clindamycin with rifampicin and cloxacillin with netilmicin, were investigated for their activity against two strains of Staphylococcus aureus (a sensitive reference strain and a methicillin-resistant clinical isolate) by means of the in vitro checkerboard technique and an in vivo infected mouse model. The mouse model allowed drug interactions to be evaluated both from the changes in the number of bacteria surviving treatment and from the measured exposure to antibiotics at the site of infection. Specimens from the latter were evaluated twice (day 0 and day 2) in each experiment. The combination of cloxacillin and netilmicin exhibited a synergistic effect against the reference strain both in vitro and in vivo, whereas synergism was obtained under in vitro conditions only against the methicillin-resistant strain. The clindamycin and rifampicin combination acted synergistically or indifferently against both strains in vitro and at day 0 of the in vivo experiments. In contrast, on day 2 of infection, this combination had significantly greater bactericidal effect (synergism) compared to the combination of cloxacillin and netilmicin. These results illustrate the difficulties of interpreting in vitro results for clinical use.

Animals↗

PubMed1993

DNA pattern and dietary habits in patients with breast cancer.

An association between dietary fat, micronutrients and breast cancer aetiology and prognosis has been found in studies of experimental animals and in epidemiological studies. The relationship between dietary habits and the nuclear DNA content of breast cancer cells was studied in 82 women aged 50-65 years. A dietary history interview was conducted within 4 months following surgery. Patients having tumours with euploid DNA pattern reported lower mean intake of saturated fatty acids (FA) in absolute terms, lower mean intake of total fat, saturated FA, and monounsaturated FA, in percentage of total energy intake (E%), a higher E% from protein, and a higher intake of vitamin D, and selenium per 10 MJ than did patients having tumours with aneuploid DNA pattern. In the stepwise logistic regression analysis, the multivariate odds ratios (OR) for having a tumour with aneuploid DNA pattern was 1.16 (95% confidence interval, 1.04-1.28) for each 1 g increase in intake of total fat (E%) and 0.95 (95% confidence interval, 0.92-0.99) for each mg increase in selenium intake per 10 MJ. When total fat was substituted with types of fat, the OR for having a tumour with aneuploid DNA pattern was 1.30 (95% confidence interval, 1.07-1.59) for each 1 g increase in intake of saturated FA (E%). These results suggest a correlation between a diet rich in fat and protein and the DNA content of breast cancer cells.

Aged↗

PubMed1993

Incidence of hip fractures in Malmö, Sweden (1950-1991).

In a 24-year sub-sample taken from a 42-year period of study (1950-1991), hip fracture incidence was analysed from a defined catchment area within one hospital. During this time, 8,256 hip fractures occurred in a generated risk population of 1,915,571 person-years. Crude incidence increased three-fold in women and five-fold in men. In men, the age-specific increase was twice as large as the age drift. In women, the two components were of equal size. The more marked increase in men caused the female:male ratio to decrease from 4.2 in 1950 to 2.4 in 1991. In men, all age classes experienced a significant yearly increase (1.6% in the 50-59 age group, 3.9% over the age of 80). In women, only the 70-79 and 80+ age groups showed a significant increase (1.4%, 2.3%). In the age-standardised curve, a levelling off occurred during the mid-80s. In women, this was attributable to changes in climate during wintertime. In men, no significant association was found with temperature. The age-standardised curve followed an approximate linear trend with an increase of 6.4/100,000/year in women and 4.9/100,000/year in men. The cumulative rate for the age group 50-79 years doubled in men but increased only by one-third in women. The impact of increasing incidence in men compared with women is discussed using an osteoporosis model consisting of base risk, senile risk, and post-menopausal risk.

Aged↗

PubMed1993

Prednimustine (Sterecyt) versus cyclophosphamide both in combination with methotrexate and 5-fluorouracil in the treatment of advanced breast cancer.

153 women with advanced breast cancer were randomly allocated for treatment with SMF [prednimustine (Sterecyt) + methotrexate + 5-fluorouracil, 83 patients] or CMF (cyclophosphamide+methotrexate+5-fluorouracil, 70 patients). Prednimustine was administered orally 100 mg/m2 daily, for 5 days, and cyclophosphamide was administered orally 100 mg/m2, for 14 days, each, every 4 weeks. Methotrexate was given at a dose of 40 mg/m2 and 5-fluorouracil at 600 mg/m2 on day 1 and 8, every 4 weeks. Leucovorin was used in 39 patients to alleviate mucositis. The two treatment groups were balanced in terms of age, performance status, lymph node status, histology, menopausal status and previous therapy. Response was evaluated in 140 patients. Of 76 patients treated with SMF, 4 had a complete and 21 a partial response (CR+PR = 33%), 40 had no change (NC) and 11 had progressive disease (PD). Of 64 patients treated with CMF, 3 had a complete and 18 a partial response (CR+PR = 33%), 30 had no change (NC) and 13 had progressive disease (PD). Time to treatment failure and survival were similar in both groups. A relationship between haematological and gastrointestinal toxicity and therapeutic efficacy was demonstrated with a superior survival and response rate recorded for patients with such toxicity than in patients without. Haematological toxicity was, in general, mild to moderate with no difference between the two groups. Alopecia (P = 0.008), nausea/vomiting (P = 0.02) and euphoria (P = 0.03) were more common in the CMF-treated group. Diarrhoea was more common in the SMF group (P = 0.03). In conclusion, SMF seems to be as efficient as CMF with regard to response rate, time to treatment failure and survival. However, SMF was tolerated better than CMF.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1993

Noninvasive ambulatory 24 h blood pressures and basal blood pressures predict development of sustained hypertension from a borderline state.

A sample of 143 male borderline hypertensives aged 35 to 45, screened from a population cohort, were subjected to psychological stress, static work, and ambulatory 24 h blood pressure (BP) monitoring to assess the predictive power of BP reactivity in the development of established hypertension. After 1 year, a follow-up showed that 21 subjects (14.7%) had developed established hypertension (causal diastolic (D) BP > or = 95 mm Hg), 25 subjects (15.7%) had become normotensive (causal DBP < 85 mm Hg), and 97 (67.8%) remained within the borderline range (causal DBP 85 to 94 mm Hg). Those who developed established hypertension had considerably higher initial basal resting blood pressures than those who remained borderline: systolic (S) BP 134.2 +/- 12.5 v 127.6 +/- 10.7 mm Hg, P < .05 and DBP 86.8 +/- 7.9 v 80.4 +/- 7.0 mm Hg, P < .01. They had also somewhat higher BP values during mental arithmetic exercises and hand-grip work (peak DBP 101.1 +/- 8.8 v 96.8 +/- 8.7 mm Hg, P < .05, and 131.4 +/- 14.8 v 123.5 +/- 12.9 mm Hg, P < .05, respectively). Those subjects who developed established hypertension had significantly higher 24 h mean blood pressures than those who remained borderline (24 h SBP 133.3 +/- 11.4 v 126.0 +/- 10.1 mm Hg, P < .01, and DBP 84.7 +/- 5.7 v 81.6 +/- 6.8 mm Hg, P < .05). This difference was attributed mainly to the differences found during daytime (07:00 to 19:00) hours but was also found to be nominally dependent upon those found during nighttime (01:00 to 07:00) hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Mutational analysis of the interaction between staphylococcal protein A and human IgG1.

The interactions have been studied between an IgG-binding domain derivative based on domain B of staphylococcal protein A (designated Z) and human immunoglobulin G class 1 (IgG1) and its Fc fragment (Fc1) respectively. Five single amino acid substituted mutant forms of Z were constructed at the gene level, produced intracellularly in Escherichia coli, purified to homogeneity and characterized. Four of these Z variants, designated Z(L17D), Z(N28A), Z(I31A) and Z(K35A), were mutated in residues suggested to be involved in binding, based on the three-dimensional structure of the complex between a one domain protein A molecule and Fc1 [Deisenhofer, J. (1981) Biochemistry, 20, 2361-2370]. The fifth mutant protein, Z(F30A), had a mutation in a phenylalanine residue which was not expected to be involved in the interaction. Analysis by far UV circular dichroism spectroscopy suggests that all Z mutant proteins have similar folds. Their respective binding to human monoclonal IgG1 and to human recombinant Fc1 were studied in a competitive binding assay using radioactively labeled Z as a tracer, demonstrating that the mutant proteins with a substitution in the postulated binding surface showed a weakened binding to both the full-length antibody and the recombinant Fc1. The affinity constants of the interactions as well as relative binding free energies from the parent Z molecule were calculated. These values were similar for each Z variant to both IgG1 and Fc1, suggesting that Fc and not Fab binding was measured also for IgG1. However, the binding strengths differ significantly, and these binding properties were used to compare the contribution of each mutated amino acid residue in the Fc interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1993

Evidence for iC3 generation during cardiopulmonary bypass as the result of blood-gas interaction.

Earlier we have shown that iC3 is generated at the blood-gas interface in vitro and that the generation of this molecule is independent of complement activation and the composition of the gas. In order to investigate whether iC3 is also generated during cardiopulmonary bypass where blood comes into contact with oxygen bubbles, two bubble oxygenators were incubated at 37 degrees C with human heparinized blood. A continuous increase in the level of iC3 was shown in the oxygen-perfused bubble oxygenator (up to 100 nmol/l after 180 min) in contrast to the unbubbled control. Similarly, in plasma drawn from patients undergoing cardiopulmonary bypass using either bubble or membrane oxygenators, the levels of iC3 were shown to increase continuously during the operation. Furthermore, this form of C3 was found to be susceptible to cleavage by factor I. The formation of iC3 at the blood-gas interface in vivo could be a mechanism by which gas bubbles induce clinical manifestations associated with complement activation, e.g. during cardiopulmonary bypass, adult respiratory distress syndrome and decompression sickness.

Adult↗