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Biomedical subjects

Peter Johansson

Publications and source records attributed to Peter Johansson.

35 records · Page 2Linked to original sources
PubMed2004

Unified treatment of fluorescence and raman scattering processes near metal surfaces.

We present a general model study of surface-enhanced resonant Raman scattering and fluorescence focusing on the interplay between electromagnetic effects and the molecular dynamics. Our model molecule is placed close to two Ag nanoparticles and has two electronic levels. A Franck-Condon mechanism provides electron-vibration coupling. Using realistic parameter values for the molecule we find that an electromagnetic enhancement by 10 orders of magnitude can yield Raman cross sections sigma(R) of the order 10(-14) cm(2). We also discuss the dependence of sigma(R) on incident laser intensity.

Journal Article↗
PubMed2004

Microarray expression profiling in melanoma reveals a BRAF mutation signature.

We have used microarray gene expression profiling and machine learning to predict the presence of BRAF mutations in a panel of 61 melanoma cell lines. The BRAF gene was found to be mutated in 42 samples (69%) and intragenic mutations of the NRAS gene were detected in seven samples (11%). No cell line carried mutations of both genes. Using support vector machines, we have built a classifier that differentiates between melanoma cell lines based on BRAF mutation status. As few as 83 genes are able to discriminate between BRAF mutant and BRAF wild-type samples with clear separation observed using hierarchical clustering. Multidimensional scaling was used to visualize the relationship between a BRAF mutation signature and that of a generalized mitogen-activated protein kinase (MAPK) activation (either BRAF or NRAS mutation) in the context of the discriminating gene list. We observed that samples carrying NRAS mutations lie somewhere between those with or without BRAF mutations. These observations suggest that there are gene-specific mutation signals in addition to a common MAPK activation that result from the pleiotropic effects of either BRAF or NRAS on other signaling pathways, leading to measurably different transcriptional changes.

Amino Acid Substitution↗
PubMed2004

Measurement of health-related quality of life in chronic heart failure, from a nursing perspective-a review of the literature.

BACKGROUND: Living with chronic heart failure (CHF) is distressful and affects daily life. Because of the lack of a cure for CHF, there has been a progressive interest in using health-related quality of life (Hr-QoL) as an outcome measurement of the treatment in patients with CHF. OBJECTIVE: The aim of this review was to describe the instruments/questionnaires used in different studies in the measurement of Hr-QoL in patients with CHF, and how they were put into operation as seen from a nursing perspective. METHOD: MEDLINE and CINAHL databases were searched from January 1995 to June 2002, by using the keywords CHF, heart failure, QoL and Hr-QoL. A total of 33 articles were analysed. RESULTS: Thirty-two different Hr-QoL questionnaires were found. Generic, disease-specific and battery approaches were different ways used to measure Hr-QoL. To assess/describe Hr-QoL, evaluate the impact of interventions and examine relations/predictors were three main objectives. However, different aspects of the concept Hr-QoL, influencing factors, how to implement the questionnaires and a lack of unified CHF criteria existed. CONCLUSIONS: To create a guideline for the measurement of Hr-QoL in CHF patients is of great importance for nurses and might generate homogeneity in the measurement methods and promote the scientific approach in the nursing care process.

Health Status↗
PubMed2004

A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies.

A prospective, open label, randomized, multicentre study was conducted, comparing the efficacy and safety of cefepime with that of imipenem-cilastatin for the management of febrile neutropenia in patients with haematological malignancies. Furthermore, the safety of early discontinuation of antibiotic therapy in patients with fever of undetermined origin (FUO) was assessed. A total of 180 patients with 207 febrile episodes were randomized at start of fever (105 episodes for cefepime and 102 episodes for imipenem). The 2 groups were comparable in terms of age, gender, underlying malignancy, prior transplantation, and presence of central venous catheters. All patients were neutropenic at inclusion with median absolute neutrophil count (ANC) 0.1 x 10(9)/l(range 0-1 x 10(9)/l), and ANC < or = 0.1 x 10(9)/l in 77% of included patients. The mean duration of neutropenia, with ANC < 0.5 x 10(9)/l was 6.2 d. Febrile episodes were classified as microbiologically documented infection (47%), FUO (43%), or clinically documented infection (10%). At final evaluation 1-2 weeks after completion of antibiotic therapy, monotherapy success rates were 40% and 51% in the cefepime and imipenem-cilastatin groups respectively (p = 0.33). The 4-week overall mortality rate was 5%. Three (2%) of the cefepime treated patients and 4 (3%) of the imipenem-cilastatin treated patients died as a result of infection. Adverse events directly related to antibiotic treatment were uncommon and did not differ between groups. Early discontinuation of antibiotic therapy in 31 patients with FUO 48 h after defervescence was not associated with an increased rate of fever relapse or mortality compared with a subgroup of 29 patients where therapy was continued.

Adolescent↗
PubMed2004

Tuberculosis in Bissau: incidence and risk factors in an urban community in sub-Saharan Africa.

BACKGROUND: Despite the long history of tuberculosis (TB) research, population-based studies from developing countries are rare. METHODS: In a prospective community study in Bissau, the capital of Guinea-Bissau, we assessed the impact of demographic, socioeconomic and cultural risk factors on active TB. A surveillance system in four districts of the capital identified 247 adult (>or=15 years) cases of intrathoracic TB between May 1996 and June 1998. Risk factors were evaluated comparing cases with the 25,189 adults living in the area in May 1997. RESULTS: The incidence of intrathoracic TB in the adult population was 471 per 100 000 person-years. Significant risk factors in a multivariate analysis were increasing age (P < 0.0001), male sex (odds ratio [OR] = 2.58, 95% CI: 1.85, 3.60), ethnic group other than the largest group (Pepel) (OR = 1.64, 95% CI: 1.20, 2.22), adult crowding (OR = 1.68, 95% CI: 1.18, 2.39 for >2 adults in household), and poor quality of housing (OR = 1.66, 95% CI: 1.24, 2.22). Household type was important; adults living alone or with adults of their own sex only, had a higher risk of developing TB than households with husband and wife present, the adjusted OR being 1.76 (95% CI: 1.11, 2.78) for male households and 3.80 (95% CI: 1.69, 8.56) for female households. In a multivariate analysis excluding household type, child crowding was a protective factor, the OR being 0.68 (95% CI: 0.51, 0.90) for households with >2 children per household. CONCLUSIONS: Bissau has a very high incidence of intrathoracic TB. Human immunodeficiency virus (HIV), increasing age, male sex, ethnicity, adult crowding, family structure, and poor housing conditions were independent risk factors for TB. Apart from HIV prevention, TB control programmes need to emphasize risk factors such as socioeconomic inequality, ethnic differences, crowding, and gender.

Adolescent↗
PubMed2004

Nursing care at night: an evaluation using the Night Nursing Care Instrument.

INTRODUCTION: Night nurses carry overall nursing responsibility for approximately half the time that patients spend in hospital. However, there is a paucity of literature that focuses on nursing care provided at night. AIM: The aim of this study was to evaluate nursing care provided at night from the perspective of both nurses and patients. METHODS: The study, which had an evaluative and a comparative design, was carried out using the Night Nursing Care Instrument at a hospital in southern Sweden. Nurses (n = 178) on night duty were consecutively selected, while the patients (n = 356) were selected by convenience sampling. RESULTS: The results showed a statistically significant difference between nurses' assessments and patients' perceptions of the nursing care provided at night in nursing interventions (P < 0.0001). In the areas of medical interventions and evaluation, no statistically significant differences were found between nurses and patients. For eight of 11 items, patients reported that they were satisfied (> or =80%) with the nursing care provided at night. CONCLUSIONS: These findings suggest that night nurses need to improve their ability to assess patients' needs for nursing care at night. A first step in this direction is for them to become aware of how patients perceive night nursing. As a second step, nurses need to increase their knowledge of which nursing actions promote patients' rest at night.

Adult↗
PubMed2003

Two-electron photon emission from metallic quantum wells.

Unusual emission of visible light is observed in scanning tunneling microscopy of the quantum well system Na on Cu(111). Photons are emitted at energies exceeding the energy of the tunneling electrons. Model calculations of two-electron processes which lead to quantum well transitions reproduce the experimental fluorescence spectra, the quantum yield, and the power-law variation of the intensity with the excitation current.

Journal Article↗
PubMed2003

The presence of a significant association between elevated PRV-1 mRNA expression and low plasma erythropoietin concentration in essential thrombocythaemia.

Approximately 45% of newly diagnosed patients with essential thrombocythaemia (ET) demonstrate subnormal plasma erythropoietin (EPO) concentrations, which constitutes a risk factor for occlusive vascular events. In 58 ET patients, a possible association between polycythaemia rubra vera-1 (PRV-1) overexpression and subnormal plasma EPO was investigated, which was always measured prior to the institution of platelet lowering agents. At the time when PRV-1 expression was measured, 28 of 58 (48%) ET patients had received platelet lowering treatment. PRV-1 expression was measured by quantitative real-time reverse transcription-polymerase chain reaction assay of mRNA extracted from purified peripheral blood buffy coat. The cycle threshold (CT) value of PRV-1 was determined and was divided with the CT value for the housekeeping GAPDH gene transcript. A quotient <0.93 was defined as PRV-1 positive. Of the ET patients 12 of 58 (21%) were PRV-1 positive and 19 of 58 (33%) demonstrated subnormal plasma EPO. In the 58 ET patients there was a significant association between low plasma EPO and PRV-1 positive results (P = 0.001). The 30 ET patients who had not received any platelet lowering treatment showed a significant (P = 0.005) relation between PRV-1 positivity and subnormal plasma EPO. No such relationship was present in the 28 ET patients who had received prior treatment with the above drugs (P = 0.147).

Adult↗
PubMed2003

Increased risk for vascular complications in PRV-1 positive patients with essential thrombocythaemia.

Essential thrombocythaemia (ET) is a heterogeneous disorder with respect to plasma erythropoietin concentration at diagnosis and clonality of haematopoiesis. Polycythaemia rubra vera-1 (PRV-1) positivity, i.e. PRV-1 mRNA overexpression, is known to be present in the vast majority of patients with polycythaemia vera and also in some patients with ET. In the present study, PRV-1 expression was quantified by real-time polymerase chain reaction in 70 ET patients; 17 of them (24%) were found to be PRV-1 positive. Ten of the 17 PRV-1 positive ET patients had experienced thromboembolic complications compared with 14 of 53 PRV-1 negative patients, the difference between the two groups being statistically significant (P=0.02). In addition, the frequency of total vascular complications, thromboembolic events and major bleedings, was significantly higher in the group of PRV-1 positive as compared with PRV-1 negative ET patients (P=0.03). The time from diagnosis of ET to the requirement of platelet-lowering therapy was significantly shorter in PRV-1 positive compared with PRV-1 negative ET patients (P=0.014). It can be concluded that PRV-1 positive patients appear to suffer from a more aggressive disorder with increased risk for vascular complications and a greater need for platelet-lowering therapy, compared with PRV-1 negative ET patients.

Adult↗
PubMed2002

Patient satisfaction with nursing care in the context of health care: a literature study.

To evaluate and improve the quality of care provided, it is of vital importance to investigate the quality of care in the context of health care. Patient satisfaction is a significant indicator of the quality of care. Consequently, quality work includes investigations that map out patient satisfaction with nursing care. To improve the quality of nursing care, the nurse needs to know what factors influence patient satisfaction. The aim of this literature study was to describe the influences on patient satisfaction with regard to nursing care in the context of health care. In the description of nursing care, we have used Henderson's nursing care model. The results describe eight domains that have an influence on patient satisfaction with nursing care: the socio-demographic background of the patients, patients' expectations regarding nursing care, the physical environment, communication and information, participation and involvement, interpersonal relations between nurse and patient, nurses' medical-technical competence, and the influence of the health care organization on both patients and nurses. The bulk of the literature included in the study came from the UK, Sweden and the USA. This means that the results should be applicable to health care in the western world. An important implication for future research is to continue to elucidate the factors that influence satisfaction with nursing care, as seen from the patient's perspective.

Clinical Competence↗
PubMed2002

Mitochondrial ATP synthase--a possible target protein in the regulation of energy metabolism in vitro and in vivo.

The increasing prevalence of obesity in the Western world has stimulated an intense search for mechanisms regulating food intake and energy balance. A number of appetite-regulating peptides have been identified, their receptors cloned and the intracellular events characterized. One possible energy-dissipating mechanism is the mitochondrial uncoupling of ATP-synthesis from respiratory chain oxidation through uncoupling proteins, whereby energy derived from food could be dissipated as heat, instead of stored as ATP. The exact role of the uncoupling proteins in energy balance is, however, uncertain. We show here that mitochondrial F1F0-ATP synthase itself is a target protein for an anorectic peptide, enterostatin, demonstrated both after affinity purification of rat brain membranes and through a direct physical interaction between enterostatin and purified F1-ATP synthase. In insulinoma cells (INS-1) enterostatin was found to target F1F0-ATP synthase, causing an inhibition of ATP production, an increased thermogenesis and increased oxygen consumption. The experiments suggest a role of mitochondrial F1F0-ATP synthase in the suppressed insulin secretion induced by enterostatin. It could be speculated that this targeting mechanism is involved in the decreased energy efficiency following enterostatin treatment in rat.

Animals↗
PubMed2002

Red cell mass, spleen size and plasma erythropoietin in polycythaemia vera and apparent polycythaemia.

Most frequently, an elevated packed cell volume (PCV) value arouses the suspicion of a polycythaemic state. The aim of the present work was to assess a few readily available variables which could help the clinician to differentiate between polycythaemia vera (PV) and apparent polycythaemia (AP). During a 5-year period, 31 consecutive newly diagnosed patients with PV were identified, and during a 4-year period 38 consecutive subjects were considered to be afflicted with AP. In each subject: (i) the red cell mass (RCM) and plasma volume were measured, (ii) the spleen size was assessed using gamma-camera imaging, and (iii) the plasma erythropoietin (EPO) concentration was determined. The diagnosis of PV was based upon recently proposed criteria. By definition, all PV patients had absolute erythrocytosis, i.e. the RCM was greater than 25% above the mean normal predicted value for the individual. There was no statistical difference between the plasma volumes for PV and AP patients. However, the mean measured/predicted plasma volume for subjects with AP was significantly lower than the mean for PV. The means for spleen scan areas (posterior and left lateral projections) for AP patients were identical to the mean reference values for our laboratory. As compared to AP, in PV the spleen scan areas were significantly increased, and the lateral spleen scan area was significantly larger than the posterior area. It was also shown that, in contrast to AP, both spleen scan areas were significantly larger in male than in female PV patients. All PV patients had plasma EPO concentrations below the lower reference limit, and in 68% of the patients undetectable EPO concentrations were present. Most AP patients (84%) had EPO values within the reference range; 8% had slightly subnormal, but not undetectable, plasma EPO levels.

Adult↗
PubMed2002

Treatment of children with Plasmodium falciparum malaria with chloroquine in Guinea-Bissau.

Children with symptomatic malaria in Bissau, Guinea-Bissau were randomly assigned to treatment with a 25 mg/kg total dose of chloroquine as recommended by the National Malaria Program or with a higher total dose of 50 mg/kg. Sixty-seven and 62 children, respectively, completed the treatment and were then followed once a week for five weeks. Treatment with a dose of 50 mg/kg was significantly more effective than treatment with 25 mg/kg in preventing recrudescence. The cumulative relative risk (95% confidence interval) of having parasitemia in the low-dose group during follow-up was 0.20 (0.08-0.52) on day 21, 0.38 (0.17-0.86) on day 28, and 0.48 (0.23-0.98) on day 35. Few adverse events were reported, although more children complained of vomiting and diarrhea on day 2 in the high-dose group compared with those in the low-dose group. However, this difference was not statistically significant. We conclude that a dose of 50 mg/kg of chloroquine could be recommended for treatment of Plasmodium falciparum malaria in Bissau. To minimize the risk of side effects, this higher dose should be given divided into two daily doses over a three-day period.

Antimalarials↗
PubMedDate not supplied

Treatment of uncomplicated malaria in children in Guinea-Bissau with chloroquine, quinine, and sulfadoxine-pyrimethamine.

With the increasing resistance to commonly used antimalarial drugs, different untested 'local' treatment regimens for malaria will arise. We compared commonly used treatment regimens for children in Guinea-Bissau. Symptomatic children with Plasmodium falciparum mono-infection were allocated at random to one of 4 treatments: 15 mg/kg quinine twice a day for 3 d (group 1); 10 mg/kg quinine twice a day for 3 d followed by a total dose of 25 mg chloroquine base given over 3 d (group 2); a total dose of 50 mg/kg chloroquine base given in 2 daily doses for 3 d (group 3), or sulfadoxine-pyrimethamine (group 4). On day 28 more children from group 1 (33%; relative risk [RR] = 2.9, 95% confidence interval [CI] 1.5-5.7) and group 2 (26%; RR = 2.1, CI 1.0-4.3) had had parasitaemia than in group 4 (12%), whereas no significant difference was found between group 3 (17%; RR = 1.3, CI 0.6-2.2) and group 4. No severe adverse reaction was observed in any of the groups. Chloroquine is still effective in Guinea-Bissau at an increased dose of 50 mg/kg, which appears safe when given orally in 2 daily doses for 3 d. Sulfadoxine-pyrimethamine could serve as an efficient, cheap and easy to administer second-line drug, leaving quinine to be used for third-line treatment. Quinine should not be used in short courses, nor does the combination of quinine and chloroquine have any advantage.

Adolescent↗
PubMedDate not supplied

Effects of long-term nocturnal oxygen treatment in patients with severe heart failure.

Sleep-disordered breathing (SDB) is common in patients with heart failure (HF) and leads to disturbed sleep. The objective of this study was to determine the persistent effects of long-term nocturnal oxygen treatment in patients with severe HF regarding (1) objective outcomes, such as sleep, SDB, cardiac function, and functional capacity; (2) subjective outcomes, such as self-assessed sleep difficulties, daytime sleepiness, and health-related quality of life (HRQOL); and (3) the relationship between objective and subjective outcomes. In this open nonrandomized experimental study, 22 patients, median age 71 years, with severe HF were studied before and after 3 months of receiving nocturnal oxygen. The measures used were overnight polysomnography, echocardiography, 6-minute walk test, self-assessed sleep difficulties (Uppsala Sleep Inventory-HF), daytime sleepiness (Epworth Sleepiness Scale), and HRQOL (36-Item Short Form Health Survey and Minnesota Living with Heart Failure Questionnaire). SDB, with a 90% dominance of central sleep apnea, occurred in 41% of the patients with severe HF before intervention. After intervention, functional capacity improved for both the whole group of patients with HF (P < .01) and HF patients with SDB (P < .05). No improvements regarding cardiac function, objective sleep, subjective sleep, or SDB were seen, except for a decrease of > or = 4% desaturations (P < .05). HRQOL did not differ significantly between HF patients with and without SDB before or after intervention with nocturnal oxygen. Long-term nocturnal oxygen treatment improved functional capacity in patients with severe HF, with or without SDB. No improvements were seen regarding sleep, daytime sleepiness, SDB, cardiac function, or HRQOL.

Aged↗