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Papers by Robert Bjerknes

Cytometry, 1990

A flow cytometric assay for the measurement of human bone marrow and blood leukocyte antigen expr... more A flow cytometric assay for the measurement of human bone marrow and blood leukocyte antigen expression, phagocytosis, and proliferation is described. Subpopulations of leukocytes were identified by their light scatter characteristics, and the expression of a myeloid differentiation antigen (designated CDw65) determined following incubation with CDw65 specific fluorescein-isothiocyanate (FITC) conjugated monoclonal antibodies (VIM2). Incubation of leukocytes with ethidium monoazide (EMA) labeled Candida albicans followed by staining with FITC conjugated VIM2 allowed the combined determination of cellular CDw65 expression and phagocytic capacity. In addition, immunostained leukocytes were fixed, and their DNA labeled with propidium iodide (PI), before CDw65 expression was measured for cells in different phases of the cell cycle. The method allows evaluation of phenotypic and functional heterogeneity, as well as cell cycle parameters, within subpopulations of cells during hematopoietic differentiation.

The growth charts currently used in Norway, are based on measurements from the 1970s and 80s. New... more The growth charts currently used in Norway, are based on measurements from the 1970s and 80s. New data are available from the Bergen Growth Study collected in 2003 - 6. In 2006, WHO published international charts for 0-5 year-old children. New growth charts based on data from the Bergen Growth Study and the Medical Birth Registry of Norway are presented for children aged 0-19 years. These were compared with existing references and with the WHO curves. Norwegian children aged 0-4 years have length, height and weight measurements that are only marginally different from those in the Norwegian growth charts in current use. In older children there has been an increase in the 50-percentile for height up to 3.4 cm in boys and 2.5 cm in girls. For children older than four years, weight for height has increased, especially for the upper percentiles. The percentile lines in the new Norwegian reference are generally positioned above the WHO standard for weight at birth, and for length/height, weight and head circumference in the age group 6 months to 5 years. The secular trends in growth mirror the need for new charts. The fact that Norwegian children differ from the WHO standards may reflect population differences relating to environment or growth potential between the populations.

Acta pathologica, microbiologica, et immunologica Scandinavica. Section C, Immunology, 1987

The production of serum opsonins and other antibodies to serogroup B serotype 15 meningococci was... more The production of serum opsonins and other antibodies to serogroup B serotype 15 meningococci was examined in 7 patients with serogroup B serotype 15 meningococcal disease and 7 volunteers immunized with a vaccine containing outer membrane proteins from serogroup B serotype 2b and 15 meningococcal strains complexed with polysaccharides from serogroups A, C, Y and W-135 meningococci. Serum opsonic activity was measured by a flow cytometric phagocytosis technique, using unfixed serogroup B Neisseria meningitidis labelled with fluorescein isothiocyanate. Serum antibodies to outer membrane complexes prepared from the meningococcal test strain, B:15:P1.16, were measured by an enzyme linked immunosorbent assay. The mean number of bacteria per phagocyte increased from 9.7 to 17.3 (mean difference 7.6, p less than 0.001) when the meningococci were opsonized with convalescent sera compared to sera obtained during the acute illness, and from 8.0 to 15.4 (mean difference 7.4, p less than 0.001...

Pediatric Allergy and Immunology, 1998

The object of the study was to assess the levels of circulating forms of the cellular adhesion mo... more The object of the study was to assess the levels of circulating forms of the cellular adhesion molecules ICAM-1, VCAM-1, E-selectin, L-selectin and P-selectin in young children with asthma and acute bronchiolitis. Thirty-nine children aged 12 to 84 months with mild or moderate asthma were studied at admission for acute asthma (n = 15) or in a stable phase (n = 24). Ten of the children with acute asthma were seen again after one month. Twenty-two children aged 1 to 17 months with acute bronchiolitis and nine non-atopic controls were also included in the study. In children with acute asthma, the mean concentration of circulating soluble ICAM-1 (sICAM-1) was increased compared to children with stable asthma (mean 442 micrograms/l versus 363 micrograms/l; p < 0.001) and to controls (363 micrograms/l; p < 0.05). The levels of sICAM-1 remained high at follow up. In children with stable asthma, the mean serum concentration of soluble L-selectin (sL-selectin) (2080 micrograms) was significantly higher than in the controls (1664 micrograms/l; p < 0.05). The levels of circulating cellular adhesion molecules were similar in atopic and non-atopic asthmatics. Children with acute bronchiolitis had increased serum levels of soluble VCAM-1 (sVCAM-1) (1637 micrograms/l versus 1019 micrograms/l in the controls; p < 0.01) and sL-selectin (2041 micrograms/l versus 1664 micrograms/l in the controls; p < 0.05). There was no difference between the levels of circulating cellular adhesion molecules in children with respiratory syncytial virus (RSV) positive and RSV negative bronchiolitis. Soluble E-selectin (sE-selectin) and soluble P-selectin (sP-selectin) in serum were not significantly increased in any of the groups studied. In conclusion, our data suggest differential patterns of circulating cellular adhesion molecules in young children with acute asthma, stable asthma, and acute bronchiolitis, which may reflect differences in the underlying inflammatory processes in these obstructive pulmonary diseases.

Pediatric Allergy and Immunology, 1996

The Journal of Trauma: Injury, Infection, and Critical Care, 1994

Polymorphonuclear neutrophilic leukocytes (PMNLs) play a key role in host defense, and phagocyte ... more Polymorphonuclear neutrophilic leukocytes (PMNLs) play a key role in host defense, and phagocyte dysfunction has been associated with increased susceptibility to infection in patients with thermal injury. We have used flow cytometric analysis (FCM) to longitudinally study PMNL expression of IgG Fc-receptor II (Fc gamma RII) and Fc-receptor III (Fc gamma RIII), as well as the complement receptors CR1 (receptor for C3b) and CR3 (receptor for C3bi) in 22 patients with large burns. Analyses of PMNL complement and immunoglobulin-mediated phagocytosis of Candida albicans were performed in parallel. Burn patient PMNL Fc gamma RIII expression was decreased to 58% of control values at admission, and remained low for the first 3 weeks. The expression of patient PMNL Fc gamma RII was not altered at admission or throughout the hospital stay. The CR1-dependent fluorescence was increased by 62% at admission, and reached a maximum at day 2, 138% greater than that of controls. The CR1 expression then gradually returned to normal at discharge. The PMNL CR3-dependent fluorescence showed an increase of 110% at admission and remained high during the first 3 weeks. The immunoglobulin-mediated phagocytosis was decreased by 12% at admission, whereas the lowest value was observed at day 10, with a reduction of 30% compared with controls. The patient PMNL complement-mediated phagocytosis of C. albicans was increased by about 160% at admission, and reached a maximum at day 2, before it gradually decreased to control levels at discharge. The expression of complement receptors correlated positively, whereas the expression of Fc gamma RIII correlated negatively, with total body surface area (TBSA) burn.(ABSTRACT TRUNCATED AT 250 WORDS)

European Journal of Surgery, 2003

Objective: To monitor longitudinally the concentrations of cytokines in the plasma of patients wi... more Objective: To monitor longitudinally the concentrations of cytokines in the plasma of patients with severe burns.

Annals of Human Biology, 2013

Previous growth references for Norwegian children were based on measurements from the 1970s and 1... more Previous growth references for Norwegian children were based on measurements from the 1970s and 1980s. New reference data, collected through the Bergen Growth Study and the Medical Birth Registry of Norway, are presented as LMS values. A cross-sectional sample of children aged 0-19 years in stratified randomized design measured in 2003-2006 as a part of the Bergen Growth Study (n = 7291) and birth data of children born in 1999-2003 from the Medical Birth Registry of Norway (n = 12 576) was used to estimate the new references by the means of the LMS method. Measurement reliability was assessed by test-rest studies. New references were constructed for length/height, weight, body mass index (BMI) and head circumference. Length/height and weight for children aged 0-4 years were similar to previous Norwegian references, but mean height increased up to a maximum of 3.4 cm in boys and 2.5 cm in girls during the pubertal years. Mean height was similar to (or slightly higher) in comparison with other recent European references. Reliability of the measurements compared well with published estimates. Because of the observed secular trends in growth, it is advised to use the new references, which have been endorsed by the Norwegian Department of Health.

Acta Paediatrica, 2013

To analyse the effect of lifestyle factors on the prevalence of overweight and obesity in 6-15-ye... more To analyse the effect of lifestyle factors on the prevalence of overweight and obesity in 6-15-year-old Norwegian children. Questionnaire data on lifestyle factors (sedentary behaviour, activity and eating habits) and prevalence numbers of overweight and obesity based on measured height and weight were analysed using multinomial logistic regression in a sample of 2281 children included in the Bergen Growth Study. More screen time increased the risk of overweight (odds ratio (OR): 1.25; p = 0.02) and obesity (OR: 1.12; p = 0.02) as did the presence of a TV in the child's bedroom (OR: 1.26 (overweight), OR: 1.81 (obese); p = 0.04). The obese children reported less sugar intake than the not overweight children (OR: 0.58; p = 0.01). Higher parental education was associated with less screen time (p = 0.02), lower frequency of TV in the child's bedroom (p = 0.001), more sports (p = 0.005), as well as eating more fruit and vegetables, less sweets, soft drinks and fast food, and more regular meals (for all, p < 0.03). Indicators of sedentary lifestyle, such as screen time and the presence of a TV in the child's bedroom, were associated with overweight and obesity in Norwegian schoolchildren. Higher parental education was generally associated with less obesogenic lifestyle.

Aids, 1996

To investigate whether the loss of CD4 cells seen in peripheral circulation of HIV-1-positive ind... more To investigate whether the loss of CD4 cells seen in peripheral circulation of HIV-1-positive individuals reflects a similar depletion of CD4 cells from lymphoid tissue. CD4 and CD8 cells in tonsillar mononuclear cell suspensions were quantified relative to tonsillar B cells, as these were thought to remain numerically unchanged in the course of HIV infection. Results were related to the CD4 cell counts in blood and to the clinical status of the patients. Blood samples and tonsillar tissue were obtained from 13 HIV-1-seropositive individuals and six seronegative controls. B cells and T-cell subsets in mononuclear cells were quantified using a three-colour flow cytometry protocol. Histological sections were morphologically classified and B-cell areas were quantified by morphometry. The B-cell fraction was confirmed to be relatively unchanged in asymptomatic HIV-1-seropositive individuals compared with controls. The tonsillar CD4 : B-cell ratios in asymptomatic individuals was similar to those seen in controls, whereas the CD4 : B-cell ratios in symptomatic HIV-1-infected individuals were greatly reduced. The tonsillar CD4 : CD8 cell ratios in HIV-1-infected individuals were much lower than those seen in controls, in the asymptomatic group due to a considerable expansion of the tonsillar CD8 cell subset, and in the symptomatic group also due to a loss of CD4 cells. We found no evidence of CD4 cell depletion in tonsillar tissue in asymptomatic HIV-1-infected individuals despite low CD4 cell counts in blood. Loss of CD4 cells from this lymphoid tissue seems to occur as a late-stage phenomenon correlated with the onset of clinical symptoms.

Cytometry, 1990

A flow cytometric assay for the measurement of human bone marrow and blood leukocyte antigen expr... more A flow cytometric assay for the measurement of human bone marrow and blood leukocyte antigen expression, phagocytosis, and proliferation is described. Subpopulations of leukocytes were identified by their light scatter characteristics, and the expression of a myeloid differentiation antigen (designated CDw65) determined following incubation with CDw65 specific fluorescein-isothiocyanate (FITC) conjugated monoclonal antibodies (VIM2). Incubation of leukocytes with ethidium monoazide (EMA) labeled Candida albicans followed by staining with FITC conjugated VIM2 allowed the combined determination of cellular CDw65 expression and phagocytic capacity. In addition, immunostained leukocytes were fixed, and their DNA labeled with propidium iodide (PI), before CDw65 expression was measured for cells in different phases of the cell cycle. The method allows evaluation of phenotypic and functional heterogeneity, as well as cell cycle parameters, within subpopulations of cells during hematopoietic differentiation.

The growth charts currently used in Norway, are based on measurements from the 1970s and 80s. New... more The growth charts currently used in Norway, are based on measurements from the 1970s and 80s. New data are available from the Bergen Growth Study collected in 2003 - 6. In 2006, WHO published international charts for 0-5 year-old children. New growth charts based on data from the Bergen Growth Study and the Medical Birth Registry of Norway are presented for children aged 0-19 years. These were compared with existing references and with the WHO curves. Norwegian children aged 0-4 years have length, height and weight measurements that are only marginally different from those in the Norwegian growth charts in current use. In older children there has been an increase in the 50-percentile for height up to 3.4 cm in boys and 2.5 cm in girls. For children older than four years, weight for height has increased, especially for the upper percentiles. The percentile lines in the new Norwegian reference are generally positioned above the WHO standard for weight at birth, and for length/height, weight and head circumference in the age group 6 months to 5 years. The secular trends in growth mirror the need for new charts. The fact that Norwegian children differ from the WHO standards may reflect population differences relating to environment or growth potential between the populations.

Acta pathologica, microbiologica, et immunologica Scandinavica. Section C, Immunology, 1987

The production of serum opsonins and other antibodies to serogroup B serotype 15 meningococci was... more The production of serum opsonins and other antibodies to serogroup B serotype 15 meningococci was examined in 7 patients with serogroup B serotype 15 meningococcal disease and 7 volunteers immunized with a vaccine containing outer membrane proteins from serogroup B serotype 2b and 15 meningococcal strains complexed with polysaccharides from serogroups A, C, Y and W-135 meningococci. Serum opsonic activity was measured by a flow cytometric phagocytosis technique, using unfixed serogroup B Neisseria meningitidis labelled with fluorescein isothiocyanate. Serum antibodies to outer membrane complexes prepared from the meningococcal test strain, B:15:P1.16, were measured by an enzyme linked immunosorbent assay. The mean number of bacteria per phagocyte increased from 9.7 to 17.3 (mean difference 7.6, p less than 0.001) when the meningococci were opsonized with convalescent sera compared to sera obtained during the acute illness, and from 8.0 to 15.4 (mean difference 7.4, p less than 0.001...

Pediatric Allergy and Immunology, 1998

The object of the study was to assess the levels of circulating forms of the cellular adhesion mo... more The object of the study was to assess the levels of circulating forms of the cellular adhesion molecules ICAM-1, VCAM-1, E-selectin, L-selectin and P-selectin in young children with asthma and acute bronchiolitis. Thirty-nine children aged 12 to 84 months with mild or moderate asthma were studied at admission for acute asthma (n = 15) or in a stable phase (n = 24). Ten of the children with acute asthma were seen again after one month. Twenty-two children aged 1 to 17 months with acute bronchiolitis and nine non-atopic controls were also included in the study. In children with acute asthma, the mean concentration of circulating soluble ICAM-1 (sICAM-1) was increased compared to children with stable asthma (mean 442 micrograms/l versus 363 micrograms/l; p < 0.001) and to controls (363 micrograms/l; p < 0.05). The levels of sICAM-1 remained high at follow up. In children with stable asthma, the mean serum concentration of soluble L-selectin (sL-selectin) (2080 micrograms) was significantly higher than in the controls (1664 micrograms/l; p < 0.05). The levels of circulating cellular adhesion molecules were similar in atopic and non-atopic asthmatics. Children with acute bronchiolitis had increased serum levels of soluble VCAM-1 (sVCAM-1) (1637 micrograms/l versus 1019 micrograms/l in the controls; p < 0.01) and sL-selectin (2041 micrograms/l versus 1664 micrograms/l in the controls; p < 0.05). There was no difference between the levels of circulating cellular adhesion molecules in children with respiratory syncytial virus (RSV) positive and RSV negative bronchiolitis. Soluble E-selectin (sE-selectin) and soluble P-selectin (sP-selectin) in serum were not significantly increased in any of the groups studied. In conclusion, our data suggest differential patterns of circulating cellular adhesion molecules in young children with acute asthma, stable asthma, and acute bronchiolitis, which may reflect differences in the underlying inflammatory processes in these obstructive pulmonary diseases.

Pediatric Allergy and Immunology, 1996

The Journal of Trauma: Injury, Infection, and Critical Care, 1994

Polymorphonuclear neutrophilic leukocytes (PMNLs) play a key role in host defense, and phagocyte ... more Polymorphonuclear neutrophilic leukocytes (PMNLs) play a key role in host defense, and phagocyte dysfunction has been associated with increased susceptibility to infection in patients with thermal injury. We have used flow cytometric analysis (FCM) to longitudinally study PMNL expression of IgG Fc-receptor II (Fc gamma RII) and Fc-receptor III (Fc gamma RIII), as well as the complement receptors CR1 (receptor for C3b) and CR3 (receptor for C3bi) in 22 patients with large burns. Analyses of PMNL complement and immunoglobulin-mediated phagocytosis of Candida albicans were performed in parallel. Burn patient PMNL Fc gamma RIII expression was decreased to 58% of control values at admission, and remained low for the first 3 weeks. The expression of patient PMNL Fc gamma RII was not altered at admission or throughout the hospital stay. The CR1-dependent fluorescence was increased by 62% at admission, and reached a maximum at day 2, 138% greater than that of controls. The CR1 expression then gradually returned to normal at discharge. The PMNL CR3-dependent fluorescence showed an increase of 110% at admission and remained high during the first 3 weeks. The immunoglobulin-mediated phagocytosis was decreased by 12% at admission, whereas the lowest value was observed at day 10, with a reduction of 30% compared with controls. The patient PMNL complement-mediated phagocytosis of C. albicans was increased by about 160% at admission, and reached a maximum at day 2, before it gradually decreased to control levels at discharge. The expression of complement receptors correlated positively, whereas the expression of Fc gamma RIII correlated negatively, with total body surface area (TBSA) burn.(ABSTRACT TRUNCATED AT 250 WORDS)

European Journal of Surgery, 2003

Objective: To monitor longitudinally the concentrations of cytokines in the plasma of patients wi... more Objective: To monitor longitudinally the concentrations of cytokines in the plasma of patients with severe burns.

Annals of Human Biology, 2013

Previous growth references for Norwegian children were based on measurements from the 1970s and 1... more Previous growth references for Norwegian children were based on measurements from the 1970s and 1980s. New reference data, collected through the Bergen Growth Study and the Medical Birth Registry of Norway, are presented as LMS values. A cross-sectional sample of children aged 0-19 years in stratified randomized design measured in 2003-2006 as a part of the Bergen Growth Study (n = 7291) and birth data of children born in 1999-2003 from the Medical Birth Registry of Norway (n = 12 576) was used to estimate the new references by the means of the LMS method. Measurement reliability was assessed by test-rest studies. New references were constructed for length/height, weight, body mass index (BMI) and head circumference. Length/height and weight for children aged 0-4 years were similar to previous Norwegian references, but mean height increased up to a maximum of 3.4 cm in boys and 2.5 cm in girls during the pubertal years. Mean height was similar to (or slightly higher) in comparison with other recent European references. Reliability of the measurements compared well with published estimates. Because of the observed secular trends in growth, it is advised to use the new references, which have been endorsed by the Norwegian Department of Health.

Acta Paediatrica, 2013

To analyse the effect of lifestyle factors on the prevalence of overweight and obesity in 6-15-ye... more To analyse the effect of lifestyle factors on the prevalence of overweight and obesity in 6-15-year-old Norwegian children. Questionnaire data on lifestyle factors (sedentary behaviour, activity and eating habits) and prevalence numbers of overweight and obesity based on measured height and weight were analysed using multinomial logistic regression in a sample of 2281 children included in the Bergen Growth Study. More screen time increased the risk of overweight (odds ratio (OR): 1.25; p = 0.02) and obesity (OR: 1.12; p = 0.02) as did the presence of a TV in the child's bedroom (OR: 1.26 (overweight), OR: 1.81 (obese); p = 0.04). The obese children reported less sugar intake than the not overweight children (OR: 0.58; p = 0.01). Higher parental education was associated with less screen time (p = 0.02), lower frequency of TV in the child's bedroom (p = 0.001), more sports (p = 0.005), as well as eating more fruit and vegetables, less sweets, soft drinks and fast food, and more regular meals (for all, p < 0.03). Indicators of sedentary lifestyle, such as screen time and the presence of a TV in the child's bedroom, were associated with overweight and obesity in Norwegian schoolchildren. Higher parental education was generally associated with less obesogenic lifestyle.

Aids, 1996

To investigate whether the loss of CD4 cells seen in peripheral circulation of HIV-1-positive ind... more To investigate whether the loss of CD4 cells seen in peripheral circulation of HIV-1-positive individuals reflects a similar depletion of CD4 cells from lymphoid tissue. CD4 and CD8 cells in tonsillar mononuclear cell suspensions were quantified relative to tonsillar B cells, as these were thought to remain numerically unchanged in the course of HIV infection. Results were related to the CD4 cell counts in blood and to the clinical status of the patients. Blood samples and tonsillar tissue were obtained from 13 HIV-1-seropositive individuals and six seronegative controls. B cells and T-cell subsets in mononuclear cells were quantified using a three-colour flow cytometry protocol. Histological sections were morphologically classified and B-cell areas were quantified by morphometry. The B-cell fraction was confirmed to be relatively unchanged in asymptomatic HIV-1-seropositive individuals compared with controls. The tonsillar CD4 : B-cell ratios in asymptomatic individuals was similar to those seen in controls, whereas the CD4 : B-cell ratios in symptomatic HIV-1-infected individuals were greatly reduced. The tonsillar CD4 : CD8 cell ratios in HIV-1-infected individuals were much lower than those seen in controls, in the asymptomatic group due to a considerable expansion of the tonsillar CD8 cell subset, and in the symptomatic group also due to a loss of CD4 cells. We found no evidence of CD4 cell depletion in tonsillar tissue in asymptomatic HIV-1-infected individuals despite low CD4 cell counts in blood. Loss of CD4 cells from this lymphoid tissue seems to occur as a late-stage phenomenon correlated with the onset of clinical symptoms.