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B Kristensen

Publications and source records attributed to B Kristensen.

At least 19 recordsLinked to original sources
PubMed1999

Using probabilistic and decision-theoretic methods in treatment and prognosis modeling.

Causal probabilistic networks, also called Bayesian networks, allow both qualitative knowledge about the structure of a problem and quantitative knowledge, derived from case databases, expert opinion and literature to be exploited in the construction of decision support systems for diagnosis, treatment and prognosis. This mixing of qualitative and quantitative knowledge will be illustrated, using the selection of antibiotics for a subset of patients with severe infections. The subset consists of patients where bacteria or fungi have been found in the blood. A simple pathophysiological model of infection is used to calculate a prognosis, dependent on the choice of antibiotics. A decision-theoretic approach is used to balance the therapeutic benefit of antibiotic treatment against the cost of antibiotics in the form of direct monetary cost, side effects and ecological cost. A retrospective trial on patients with bacteria or fungi in the blood stemming from the urinary tract indicates that with this approach, it may be possible to suggest balanced choices of antibiotics that not only achieve greater therapeutic benefit, but also reduce the cost of therapy.

Anti-Bacterial Agents↗
PubMed1999

Antibiotic resistance patterns among blood culture isolates in a Danish county 1981-1995.

All episodes of bacteraemia during a 15-year period (1981-1995) in the County of Northern Jutland, Denmark, were analysed with regard to antibiotic resistance. A total of 8840 isolates from 7938 episodes of bacteraemia was identified. Over time, no changes in bacterial aetiology were noted. Three isolates of Staphylococcus aureus were methicillin resistant (0.2%) and six were gentamicin resistant (0.4%). Among coagulase-negative staphylococci a 14% increase in resistance to penicillin was observed (95% confidence intervals, CI: 2-26%). Likewise, the frequency of resistance to methicillin, gentamicin and erythromycin increased, the corresponding figures being 38% (CI: 26-50%), 26% (CI: 14-38%) and 32% (CI: 16-50%), respectively, whereas a 14% decrease in resistance to streptomycin was recorded (CI: 4-24%). A 20% (CI: 2-37%) increase of coagulase-negative staphylococci resistant to three or more antibiotics was observed. The frequency of ampicillin resistance increased by 9% among Escherichia coli (CI: 4-13%) and by 10% (CI: 6-14%) in all Enterobacteriaceae. Among Enterobacteriaceae the level of resistance to third-generation cephalosporins, carbapenems, aminoglycosides and fluoroquinolones remained low (<1%). The frequency of resistance to three or more antibiotics remained fairly stable among Enterobacteriaceae, although a slight increase was noted among E. coli (5%; CI: 0-10%) The recommended regimen for empirical antibiotic treatment in this region (a combination of penicillin G or ampicillin and an aminoglycoside) provided an overall coverage of 94% (CI: 94-95%), although a slight decrease was noted at the end of the period. In conclusion, acquired antibiotic resistance was maintained at a low level compared with most other European countries and regions during the 15-year period studied.

Aminoglycosides↗
PubMed1999

Secular trends in incidence and mortality of bacteraemia in a Danish county 1981-1994.

We estimated the incidence and mortality of bacteraemia in the County of North Jutland and examined factors that could explain the changes observed. A population-based survey of bacteraemia was conducted in the Danish County of North Jutland during 1981-1994. Data were retrieved from a regional bacteraemia register. The mortality was determined through linkage to the Danish Civil Registration System. A total of 7198 bacteraemias were detected, and the annual incidence increased from 76 per 100,000 person-years in 1981 to 153 in 1994. One major determining factor was a change in blood culture system with a higher volume of blood per sample, but annual numbers of blood cultures also increased. The 30-day mortality rate increased from 17 to 40 per 100,000 person-years during the study period, whereas the case-fatality rate remained constant (23.6%; 95% confidence intervals 22.6%-24.6%). The number of bacteraemias increased significantly. This observation could be explained only partly by changes in demography, in blood culture system, and in diagnostic activity. The case fatality rate remained constant despite the fact that more people were diagnosed with bacteraemia; this indicates that, with recent blood culture practice, more clinically significant bacteraemias are diagnosed.

Adolescent↗
PubMed1999

Hyperhomocysteinemia and hypofibrinolysis in young adults with ischemic stroke.

BACKGROUND AND PURPOSE: Data from epidemiological and case-control studies suggest that increased total homocysteine (tHcy) levels are associated with increased risk for thromboembolic disease. The mechanisms by which hyperhomocysteinemia contributes to thrombogenesis are incompletely understood. The main objectives of this study of young ischemic stroke patients were (1) to examine fasting and post-methionine load levels of tHcy, (2) to ascertain the genotype frequency of the C677CT mutation in the methylenetetrahydrofolate reductase gene (TT genotype), and (3) to study the possible interaction between plasma tHcy levels and fibrinolytic factors. METHODS: This case-control study was based on 80 consecutive patients aged 18 to 44 years admitted between January 1992 and May 1996 as a result of a first-ever ischemic stroke. Forty-one healthy control subjects were recruited. Measurement of fasting tHcy and post-methionine load levels and evaluation of the fibrinolytic system were undertaken at least 3 months (mean, 5.1+/-1. 9 months) after admission. Genotyping of the methylenetetrahydrofolate reductase gene was performed. RESULTS: Although the increase after methionine loading (ie, postload tHcy minus fasting-level tHcy) was significantly higher among patients, there was no difference in fasting and postload tHcy levels. After adjustment for conventional risk factors, elevated postload increase tHcy levels were associated with a 4.8-fold increased risk of ischemic stroke. There was no difference between patients and control subjects in either TT genotype frequency or T allele frequency. Abnormal response to methionine loading was associated with higher tissue plasminogen activator (tPA) mass concentration, higher plasminogen activator inhibitor-1 levels, and lower tPA activity. After adjustment for age, sex, body mass index, serum cholesterol, and triglycerides, an abnormal increase in postload tHcy levels remained significantly associated with tPA mass concentration levels (P=0.03). CONCLUSIONS: A moderately elevated increase in tHcy levels after methionine loading was associated with an increased risk for ischemic stroke in young adults. In contrast, fasting tHcy levels did not differ between patients and controls. A moderately elevated increase in tHcy after methionine loading may provide a additional thrombogenic risk mediated in part by interactions with the fibrinolytic system. In young stroke patients, a methionine loading test to detect hyperhomocysteinemia should always be considered in the convalescent phase of the disease.

Adolescent↗
PubMed1998

Bone mineral changes during pregnancy and lactation: a longitudinal cohort study.

1. The influence of pregnancy, lactation and weaning on bone mineral density in healthy women was investigated during a 2 year prospective study of 59 pregnant and lactating women from the 18th week of gestation. 2. Bone mineral density was measured by dual energy X-ray absorptiometry at the non-dominant radius ultra distally and more proximally in the 18th and 37th weeks of gestation, and 0, 3, 6, 12 and 18 months after delivery. Measurements of bone mineral density of the lumbar spine, the proximal femur and the whole body were performed at all dates after delivery. 3. Reappearance of menstruation after delivery averaged 6.1 months; mean lactating period was 8.7 months. During pregnancy and lactation bone mineral density tended to decrease, but different measuring sites showed different patterns of bone mineral density changes. The reduction in the ultra distal radius during pregnancy amounted to 2%, and no further changes were observed here during lactation. After delivery, reduction in mean bone mineral density was most pronounced in the spine (5.2% in 3 months), but the fall in bone mass tended to revert after resumption of menstruation. Bone mineral density was still reduced by 3.3% after 12 months in women with menstruation resumption later than 8 months after delivery. No significant reduction was observed 18 months after delivery. No association with calcium intake, weight changes or initial bone mineral density was observed. High calcium intake did not protect against bone mineral loss in the spine and the femur. 4. Thus it can be concluded that bone loss during pregnancy and lactation took place mainly from the trabecular skeleton. Resumption of menstruation tended to result in a regain of bone mass towards baseline.

Absorptiometry, Photon↗
PubMed1998

Variable number of pig MHC class I genes in different serologically defined haplotypes identified by a 3'-untranslated region probe.

To estimate the number of porcine class I major histocompatibility genes, a short class I cDNA probe from the 3'-untranslated region was developed to be used in restriction fragment length polymorphism analysis. Six clones isolated from a pig spleen cDNA library were sequenced from their 3'-untranslated region. Three different transcripts were identified, one probably derived from the class I PD7 locus and two showing highest homology to the PD1 and the PD14 genes, respectively. Class I typing was performed both by restriction fragment length polymorphism and serology. Segregation of class I haplotypes was followed in one three-generation family (European Wild Boar x Large White: Swedish Yorkshire) and in six two-generation families (Duroc, Yorkshire and Chester White), for a total of 266 pigs. Twenty different class I haplotypes were identified either with restriction fragment length polymorphism and/or serological typing. Furthermore, previously unpublished serological haplotypes H62, H67 and H68 were identified. Two to seven polymorphic and three monomorphic fragments were detected in different restriction fragment length polymorphism haplotypes indicating that the number of class I genes in the investigated haplotypes varies.

Animals↗
PubMed1998

Survival in breast cancer patients after the first episode of hypercalcaemia.

OBJECTIVES: To investigate hypercalcaemia (serum ionized calcium (S-Ca2+) > 1.35 mmol L(-1)) in breast cancer patients before and after the introduction of bisphosphonates and the effect of disease- and treatment-related factors on survival. DESIGN: Prospective and retrospective registration of covariates. SETTING: A department of oncology in a university hospital. SUBJECTS: A consecutive cohort of 212 hypercalcaemic patients never treated with bisphosphonate was identified prospectively (period 1) and 193 patients with metastases were classified into three groups: mild (S-Ca2+ < 1.48: n=102). moderate (1.48 < or = S-Ca2+ < or = 1.60; n=41). and severe hypercalcaemia (S-Ca2+ > 1.60 mmol L(-1); n=50). Fifty-one patients with severe hypercalcaemia all treated with bisphosphonate except one were identified retrospectively (period 2). RESULTS: For period 1 median survival was 6.7 months. Survival was significantly decreased in the two groups with the highest initial S-Ca2+ (P < 0.0001). Median survival times in severely hypercalcaemic patients from periods 1 and 2 were 1.4 (9 5(% confidence interval 0.8-2.1) and 2.2 (95% confidence interval 1.3-3.1) months, respectively. In a Cox model for period 1 significant covariates were: WHO performance, extent of metastases, whether systemic anticancer treatment could be given, and haemoglobin, but not S-Ca2+. CONCLUSION: Prognosis is poor in hypercalcaemic breast cancer patients with WHO performance 3-4 and advanced metastatic disease when effective systemic treatment can no longer be offered. Bisphosphonate treatment does not seem to improve survival in severe hypercalcaemia. Antihypercalcaemic treatment of mild malignancy-associated hypercalcaemia appears not to be vital. Therapeutic efforts should be aiming at patients with moderate hypercalcaemia.

Breast Neoplasms↗
PubMed1998

Effects of transient and persistent cerebrospinal fluid drainage on sleep disordered breathing in patients with idiopathic adult hydrocephalus syndrome.

OBJECTIVES: To examine sleep disordered breathing including obstructive sleep apnoea in patients with idiopathic adult hydrocephalus syndrome (IAHS) and to study the effects of CSF drainage and shunting procedure on sleep disordered breathing. METHODS: In 17 patients with IAHS polysomnographic investigations were performed before and after lumbar CSF drainage and after shunt operation. RESULTS: Baseline investigations documented a high prevalence of sleep related obstructive respiratory events (respiratory disturbance index >10 in 65% of the patients) and impaired sleep structure. There was no correlation between respiratory disturbance index and CSF pressure. Minimum oxygen saturation was highly correlated with cognitive function. Neither lumbar CSF drainage nor shunting alleviated the respiratory disturbance index. REM and delta sleep increased initially after shunting but there was no sustained effect on sleep quality. CONCLUSIONS: Sleep disordered breathing is a prevalent finding in patients with IAHS. The shortcoming of CSF drainage to improve sleep disordered breathing either transiently or permanently implies that sleep disordered breathing is a coexistent condition, or an irreversible consequence of the hydrocephalus, with a potential of causing additional dysfunction in IAHS.

Aged↗
PubMed1998

Increased fibrinogen levels and acquired hypofibrinolysis in young adults with ischemic stroke.

BACKGROUND AND PURPOSE: Elevated fibrinogen levels and abnormalities in the fibrinolytic system are related to the occurrence of cardiovascular events. However, the role of these factors in the evolution of cerebrovascular disease has received less attention, in particular in young stroke patients. The aim of this study was to evaluate possible abnormalities in plasma fibrinogen levels and the state of the fibrinolytic system in young adults with a first-ever ischemic stroke. METHODS: This study is based on 102 consecutive patients aged 18 to 44 years admitted between January 1991 and May 1996 as a result of a first ischemic stroke. Forty-one healthy controls were recruited. Evaluations of anthropometric/metabolic variables, plasma fibrinogen levels, and the fibrinolytic system were undertaken >/=3 months (mean, 5.4+/-2.0 months) after admission. RESULTS: Patients had lower tissue plasminogen activator activity and increased plasminogen activator inhibitor type 1 activity at baseline, as well as increased tissue plasminogen activator mass concentration both at baseline and after a venous occlusion test. Overall, there were no significant differences between the main etiologic subgroups regarding plasma fibrinogen levels and fibrinolytic variables. Baseline fibrinolytic variables were strongly correlated with body mass index, serum triglycerides, and cholesterol levels. After adjustments in multivariate models, fibrinogen levels and tissue plasminogen activator mass concentration both at baseline and after venous occlusion test remained significantly increased in patients. Logistic multiple regression analyses indicated that plasma fibrinogen was a strong predictor of ischemic stroke (odds ratio, 11.25; 95% CI, 3.27 to 38. 69). CONCLUSIONS: Increased fibrinogen levels and tissue plasminogen activator mass concentration are independently associated with ischemic stroke in young adults. Metabolic perturbations are closely interrelated with aberrations in tissue plasminogen activator and plasminogen activator inhibitor type 1 activity in these patients, findings consistent with an acquired hypofibrinolysis.

Adolescent↗
PubMed1998

Cognitive impairment in young adults with infratentorial infarcts.

OBJECTIVE: To describe cognitive functions and functional outcome in young patients with isolated infratentorial infarcts. BACKGROUND: Contemporary knowledge implies a cerebellar contribution to cognitive behavior. Neuropsychological examination of patients with selective cerebellar lesions provides an opportunity to document the existence and nature of clinically relevant cognitive manifestations from lesions of the cerebellum. METHODS: Prospective case series. The patients were assessed acutely and at 4 and 12 months after onset. Twenty-four patients from a consecutive series of 105 patients aged 18 to 44 years with cerebral infarction had a brain stem or cerebellar infarction. Fourteen age-matched controls were used for neuropsychological comparisons. Evaluation included MRI, angiography, and transesophageal echocardiography. Disability and neurologic dysfunction were assessed by the modified Rankin scale, NIH stroke scale, and maximal working capacity. A comprehensive neuropsychological battery was performed at baseline in 20 of the 24 patients. RESULTS: Eighteen patients had a cerebellar infarct. Two patients had lateral medullary infarcts, and two isolated pontine infarcts. Twenty-two patients had a favorable outcome according to the modified Rankin scale (grade 0-2) and the NIH scale. In contrast, 12 patients were granted full or partial sick leave at the 4 months follow-up, and 10 patients at 12 months. Patients generally performed worse than controls in various aspects of cognitive function, especially in tasks concerning working memory, the temporary storage of complex information, and cognitive flexibility. Measures of verbal IQ (r = -0.74) and performance IQ (r = -0.78) were related to the size of the infarct. The block design task performance in the early poststroke period predicted maximal working capacity at 12 months. CONCLUSIONS: Cerebellar damage impairs central aspects of attention and visuospatial skills. In contrast, intelligence and episodic memory remain unchanged. When the lesion involves large portions of the cerebellar hemispheres, changes concerning broad areas of intelligence may occur. The prognosis is favorable for neurologic dysfunction, but cognitive deficits may prevent return to work.

Adolescent↗
PubMed1998

Diagnosis of osteoporosis by planar bone densitometry: can body size be disregarded?

Bone densitometry using dual energy X-ray absorptiometry (DXA) is frequently used to diagnose osteoporosis and to identify patients at risk of later fractures. The parameters of interest are bone mineral content (BMC) and bone mineral areal density (BMD). Bone densitometry results have a large overlap between normals and patient with fractures. This would suggest that other factors are important for the development of fractures or that bone densitometry is not used optimally. It is generally believed that the conversion of BMC to BMD by division of the former by the projected bone area is a good normalization procedure. Other normalization procedures have been attempted in the past with little success. We hypothesized that this might be due to a blurring effect of time since menopause, and that body size could be demonstrated to have an effect on measured BMC and BMD, if this time effect could be eliminated. The results of this study, comprising 1625 early post-menopausal women studied at virtually the same time since menopause, confirm that this is the case. Body surface area was the parameter among conventional body size variables showing the highest correlation with BMC and BMD. It was clearly shown that low values of BMD were seen more often in the lowest than in the highest body surface area quartile. The difference between quartiles was statistically significant. Simple division of BMC by actual body surface area or division of BMD by the square root of body surface removed the uneven distribution between the body surface area quartiles for lumbar spine and femoral neck measurements, and reduced it at peripheral measuring sites. It is suggested that BMC and BMD of the lumbar spine and the femoral neck should be normalized as described to avoid overdiagnosis of osteoporosis in persons of petite body stature and underdiagnosis in tall ones.

Absorptiometry, Photon↗
PubMed1998

Can hospital discharge diagnosis be used for surveillance of bacteremia? A data quality study of a Danish hospital discharge registry.

OBJECTIVE: To assess the data quality of septicemia and sepsis registration in a hospital discharge registry in the County of Northern Jutland, Denmark. DESIGN: Comparison of data from the discharge registry of an 880-bed, public, urban hospital in the County of Northern Jutland with data from a computerized bacteremia database at the regional department of clinical microbiology. SETTING: Urban hospital with approximately 45,000 admissions per year. PATIENTS: The study included 406 episodes of bacteremia in the bacteremia database and 83 discharges with the diagnosis of septicemia registered in the hospital discharge registry between January 1, 1994, and December 31, 1994. INTERVENTIONS: None. RESULTS: Eighteen episodes were registered in both the hospital discharge registry and the bacteremia database. Using the bacteremia database as reference standard, the sensitivity for the diagnosis of septicemia in the hospital discharge registry was 4.4% (18/406; 95% confidence intervals [CI95, 2.4%-6.4%]). By review of hospital records, we estimated the positive predictive value of septicemia registration in the hospital discharge registry as 21.7% (18/83; CI95, 12.8%-30.5%). No blood culture had been obtained in 44.4% (36/81; CI95, 33.6%-55.3%) of the cases with a discharge diagnosis of septicemia. In 33.3% (27/81; CI95, 23.1%-43.6%), the discharge diagnosis of septicemia was given, although blood cultures were negative. CONCLUSIONS: The hospital discharge registry revealed numerous misclassifications, and the system was found not suited for surveillance of, or research in, bacteremia at present.

Bacteremia↗
PubMed1997

Cholinergic regulation of VIP gene expression in human neuroblastoma cells.

The effects of carbamylcholine (CCh) on the gene expression of the neuropeptide vasoactive intestinal polypeptide (VIP) were studied using two human neuroblastoma cell lines. NB-1 and BE(2)M17. CCh caused a fast increase in VIP mRNA level in both cell lines which was followed by an increase in VIP immunoreactivity. The time-course of the induction of both mRNA and peptide differed, however, between the two cell lines. No morphological changes of the cells were observed during 6 days of stimulation. The effect was mediated by the muscarinic class of acetylcholine receptors, since it could be totally abolished by atropine. Since CCh caused an accumulation of inositol-1,4,5-triphosphate, it is likely that muscarinic receptor subtype M1, M3 or M5 is involved. Experiments with the translational inhibitor, cycloheximide, showed that CCh mediated a direct effect on the VIP gene expression. By combining gel permeation chromatography with radiommunoassays using antisera specific for the various VIP-precursor products, immunoreactive peaks eluting as the synthetic peptides were found in both cell lines. In addition, earlier eluting peaks which could represent partially processed or extended VIP forms were found. After CCh induction the concentration of all prepro VIP-derived products increased, and there was a tendency towards a shift to more fully processed VIP. The findings give new evidence for a direct regulation of VIP gene expression in human neuronal cells by cholinergic agents.

Brain Neoplasms↗
PubMed1997

[Stent implantation in genuine coronary vessels--with and without guidance of intracoronary ultrasound].

The purpose of the present study was to evaluate the clinical and angiographic results of implantation of stents in the native coronary circulation. In group A (n: 33) implantation was assessed by angiography, in group B (n: 17) also by ICUS. There were no procedure related deaths, transmural myocardial infarctions or acute coronary by-pass operations (CABG). The diameter of stenosis before treatment was 86% and 82% in group A and B, respectively. In both groups an overdilatation was seen following stent implantation, 5% in group A versus 22% in group B (p < 0.01). At four months follow-up 80% in group A and 81% in group B were symptom-free or improved (NS). Angiographic restenosis (> or = 50% reduction of vessel diameter) was found in 10.3% in group A versus 20.0% in group B (NS). Our results are in accordance with other coronary stent studies showing reduced acute coronary occlusion and CABG incidence and a low restenosis rate as compared to conventional balloon angioplasty. The role of ICUS in the implantation of intracoronary stents remains unsettled.

Adult↗
PubMed1997

Microbiology of semen specimens from males attending a fertility clinic.

The relationship between semen quality, pyospermia and bacteriology was studied in 201 semen specimens from male patients attending a fertility clinic. Semen quality parameters were within normal limits in 115 (57%) patients, slightly reduced in 60 (30%), and 26 (13%) had findings indicating reduced fertility. Twelve patients (6%) had pyospermia. In 182 patients, 552 microorganisms were detected, including Enterobacteriaceae (2.8%), Gardnerella vaginalis (9.6%), Chlamydia trachomatis (1.6%), Mycoplasma genitalium (0.9%), and Ureaplasma urealyticum (11.8%). Semen quality was neither related to occurrence of microorganisms nor pyospermia. However, pyospermia was associated with simultaneous growth of Gardnerella vaginalis and Ureaplasma urealyticum. The exact nature of this association could not be ascertained, in as far as the males were not questioned about urethritis symptoms.

Adult↗
PubMed1997

Epidemiology and etiology of ischemic stroke in young adults aged 18 to 44 years in northern Sweden.

BACKGROUND AND PURPOSE: The aim of this study was to conduct a population-based epidemiological survey among young adults aged 18 to 44 years in Northern Sweden and furthermore to gain further insight into the etiology of ischemic stroke in this age group. METHODS: Two studies were done. In the first part, epidemiological data were collected to calculate incidence and mortality from 1991 through 1994. This was based on the World Health Organization Northern Sweden MONICA register of acute stroke events. Eighty-eight first-ever ischemic stroke patients were identified during that period. In the second part, 107 consecutive patients aged 18 to 44 years with ischemic stroke referred to a university hospital were studied prospectively during a 5-year period and were extensively evaluated according to a standardized protocol. On the basis of modified Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria, the patients were classified into eight subtypes of ischemic stroke. RESULTS: The average population-based annual incidence rate for ischemic stroke (cases per 100,000 per year) was 11.3 (95% confidence interval, 6.7 to 16.1). The case-fatality rate was 5.7%. According to the modified TOAST criteria, a probable cause of ischemic stroke was identified in 36% and remained unexplained in 21% of cases. Spontaneous cervical arterial dissection was the leading probable etiology (13%). Patent foramen ovale or atrial septal aneurysm was a possible cause of stroke in 28% of cases. The percentages of ischemic stroke attributed to IgG anticardiolipin antibodies (4.7%), atherothrombotic vasculopathy (3.7%), oral contraceptive use (7%), and migraine (1%) were lower than reported in recent clinical series. CONCLUSIONS: The incidence rate for ischemic stroke was higher than previously reported from most countries in Western Europe. The higher incidence was not explained by a higher prevalence of premature atherosclerotic vasculopathy. Without the additional diagnostic information derived from advanced cardiac imaging, the proportion of indeterminate cases would have constituted 37% of the patients.

Adolescent↗