Biomedical subjects

B Larsen

Publications and source records attributed to B Larsen.

At least 55 records · Page 3Linked to original sources

PubMed1999

Typing of clinical Mycobacterium avium complex strains cultured during a 2-year period in Denmark by using IS1245.

In the present study restriction fragment length polymorphism analyses with the recently described insertion sequence IS1245 as a probe was performed with clinical Mycobacterium avium complex strains cultured in Denmark during a 2-year period. The overall aim of the study was to disclose potential routes of transmission of these microorganisms. As a first step, the genetic diversity among isolates from AIDS patients and non-human immunodeficiency virus (HIV)-infected patients was described. In addition, a number of isolates from nonhuman sources cultured during the same period were analyzed and compared to the human isolates. A total of 203 isolates from AIDS patients (n = 90), non-HIV-infected patients (n = 91), and nonhuman sources (n = 22) were analyzed. The presence of IS1245 was restricted to Mycobacterium avium subsp. avium isolates. The majority of human isolates had large numbers of IS1245 copies, while nonhuman isolates could be divided into a high-copy-number group and a low-copy-number group. Groups of identical strains were found to be geographically widespread, comprising strains from AIDS patients as well as strains from non-HIV-infected patients. Samples of peat (to be used as potting soil) and veterinary samples were found to contain viable M. avium isolates belonging to genotypes also found in humans.

AIDS-Related Opportunistic Infections↗

PubMed1999

Determination of the complex between urokinase and its type-1 inhibitor in plasma from healthy donors and breast cancer patients.

BACKGROUND: The complex between urokinase (uPA) and its type-1 inhibitor (PAI-1) is formed exclusively from the active forms of these components; thus, the complex concentration in a biological sample may reflect the ongoing degree of plasminogen activation. Our aim was to establish an ELISA for specific quantification of the uPA:PAI-1 complex in plasma of healthy donors and breast cancer patients. METHODS: A kinetic sandwich format immunoassay was developed, validated, and applied to plasma from 19 advanced-stage breast cancer patients, 39 age-matched healthy women, and 31 men. RESULTS: The assay detection limit was <2 ng/L, and the detection of complex in plasma was validated using immunoabsorption, competition, and recovery tests. Eighteen cancer patients had a measurable complex concentration (median, 68 ng/L; range, <16 to 8700 ng/L), whereas for healthy females and males the median signal values were below the detection limit (median, <16 ng/L; range, <16 to 200 ng/L; P <0.0001). For patient plasma, a comparison with total uPA and PAI-1 showed that the complex represented a variable, minor fraction of the uPA and PAI-1 concentrations of each sample. CONCLUSION: The reported ELISA enables detection of the uPA:PAI-1 complex in blood and, therefore, the evaluation of the complex as a prognostic marker in cancer.

Aged↗

PubMed1998

Real-time isoform analysis by two-dimensional chromatography of a monoclonal antibody during bioreactor fermentations.

A humanized monoclonal antibody specific for L-selectin exhibits two distinct isoforms that are distinguishable by a charged group modification on one of the antibody light chains. The added charge allows baseline separation of the isoforms by anion-exchange chromatography. Since this modification most likely results from specific enzymatic activity within the Golgi complex, it is possible that fermentation conditions may affect the relative amounts of the isoforms produced. Herein is described a two-dimensional chromatographic method for quantifying the relative amounts of the isoforms from fermentation broths, in real time.

Antibodies, Monoclonal↗

PubMed1998

Frequent mutations of the p53 gene in cutaneous melanoma of the nodular type.

The frequency and significance of p53 alterations in cutaneous melanoma have not been completely clarified. In the present study, 31 primary melanomas of the nodular type and 15 metastases occurring between 1981 and 1983 were studied with respect to mutations in exons 7 and 8, as well as to p53 protein immunostaining using different antibodies. Altogether 13% of the primary tumors showed strong p53 staining using the DO-7 antibody. Different results were obtained with other antibodies. Seven mutations were found in primary and metastatic tumors; all of these were single base changes, most of which occurred in the core domain of the p53 protein responsible for sequence-specific DNA binding (residues 102-293). The mutations were not significantly associated with p53 staining results, and p53 alterations (mutations or marked immunopositivity) had no prognostic value. Our results indicate that point mutations in exons 7 and 8 are more frequent than previously reported in primary melanomas, and such changes may be important for the development of certain melanoma subgroups.

Adult↗

PubMed1998

Effect of gliotoxin on human polymorphonuclear neutrophils.

OBJECTIVES: Candida albicans is known to produce gliotoxin, which has several prominent biological effects, including immunosuppression. Interference with host defenses may arise from the effects of this toxin on leukocyte structure and function. METHODS: Flow cytometric analysis revealed that polymorphonuclear leukocytes (PMN) were more sensitive to gliotoxin than were mononuclear cells. Structural and various functional aspects of PMN exposed to gliotoxin were studied. RESULTS: Gliotoxin at (1 microgram/mL) did not affect the viability but did diminish PMN chemotaxis and reduced their ability to ingest particles. Other functional aberrations included decreased nitroblue tetrazolium dye reduction, decreased superoxide production, and release of lactoferrin suggesting by degranulation. Gliotoxin also affected the ability of PMN to kill Escherichia coli. CONCLUSIONS: This study suggests a previously unrecognized potential virulence factor of C. albicans that could contribute to persistence of yeast colonization or recurrence of symptomatic infection through diminished host resistance.

Candida albicans↗

PubMed1998

17-beta-estradiol upregulates the stress response in Candida albicans: implications for microbial virulence.

OBJECTIVE: The influence of 17-beta-estradiol on the stress response of Candida albicans was studied. METHODS: The survival of clinical isolates of C. albicans treated with 17-beta-estradiol after heat and oxidative stress was measured by viable plate counts. Cellular proteins were analyzed via SDS-PAGE. RESULTS: The heat stress response induced by 17-beta-estradiol in C. albicans grown at 25 degrees C protected the organisms against the lethal temperature of 48.5 degrees C, as shown by viable plate counts. 17-beta-estradiol also enhanced protection of C. albicans against oxidative stress (menadione exposure). SDS-PAGE analysis of cytoplasmic extracts revealed proteins induced by 17-beta-estradiol were similar to those induced by heat. CONCLUSION: 17-beta-estradiol enhances survival of C. albicans under heat and oxidative stresses. The proteins induced by 17-beta-estradiol are probably heat shock proteins. Because heat shock proteins are considered to be virulence factors, 17-beta-estradiol may function to promote in vivo survival.

Candida albicans↗

PubMed1998

[Does intrathecal clonidine prolong the effect of spinal anesthesia with hyperbaric mepivacaine? A randomized double-blind study].

BACKGROUND: Clonidine, an alpha 2-receptor agonist, has been reported to prolong the blocking actions of local anaesthetics. The aim of this study was to investigate the effects of spinally injected clonidine on the duration of spinal anaesthesia by mepivacaine and on the postoperative demand for analgesics. METHODS: Forty-five patients who had transurethral urological surgery under spinal anaesthesia were randomized to 3 groups (n = 15 each) and studied in a double-blind fashion. Group I received 80 mg mepivacaine 4% only, while in group II mepivacaine was combined with 75 micrograms clonidine intraspinally and in group III with 150 micrograms clonidine. Onset time, spread of anaesthesia, duration of sensory and motor blockade, regression of anaesthesia and postoperative demand for analgesics were recorded. In addition heart rate and mean arterial pressure were measured at regular intervals. RESULTS: Clonidine had no effect on the onset time and spread or intensity of spinal anaesthesia. The higher dose of clonidine significantly prolonged the duration of sensory blockade by 50 min and the duration of motor block by 40 min, while 75 micrograms had no significant effect. Heart rate and mean arterial pressure were significantly reduced in both clonidine groups when compared to plain mepivacaine. There was no significant reduction in postoperative analgesic demand. CONCLUSION: While clonidine prolonged sensory analgesia, there was also an undesirable prolongation of motor block postoperatively. In addition, there was a significant and long lasting reduction in heart rate and mean arterial pressure in both clonidine groups. Unfavourably, postoperative demand of analgesics was not reduced by spinal injection of clonidine. Thus, the routine addition of clonidine for spinal anaesthesia with local anaesthetics is not recommended.

Adrenergic alpha-Agonists↗

PubMed1998

Longitudinal investigation of candida vaginitis in pregnancy: role of superimposed antibiotic use.

OBJECTIVE: To evaluate the purported association of antibiotic use and subsequent symptomatic Candida vaginitis among pregnant women. METHODS: Two hundred fifty obstetric patients were followed in a prospective, culture-based, longitudinal, and observational study from the first antepartum appointment through the postpartum visit at 6 weeks. All patients were cultured for yeast (Nickerson agar) initially. Patients with symptoms and microscopic evidence of vaginitis at the initial visit were followed through pregnancy but were not analyzed with asymptomatic individuals who had vaginal cultures for Candida at the first visit and at subsequent visits if they developed vulvovaginal symptoms. Patients were categorized as colonized or uncolonized on the basis of initial cultures and were evaluated at least monthly for antibiotic use and vaginal complaints. In addition, hospital records were reviewed after the final visit to document antibiotic use or vaginal infection. RESULTS: Asymptomatically colonized patients were at a threefold greater risk of developing symptoms than were uncolonized patients (P < .001). Among women receiving antibiotics during pregnancy, 6.1% developed symptoms of Candida vaginitis compared with 15.6% of women who did not receive antibiotics. For the entire study population, 46% of the patients received at least one course of antibiotic therapy and 21% had multiple courses. Only three of the seven who became symptomatic with yeast vaginitis did so within 4 weeks of treatment. Many of the antibiotic regimens were prescribed by providers other than the obstetrician. CONCLUSION: Antibiotic treatment during pregnancy was frequent in the study population, but was not associated with a significant risk of developing Candida vaginitis.

Antifungal Agents↗

PubMed1998

Transient neurologic symptoms after spinal anesthesia: an epidemiologic study of 1,863 patients.

BACKGROUND: Recent evidence suggests that transient neurologic symptoms commonly follow lidocaine spinal anesthesia. However, information concerning factors that affect their occurrence is limited. Accordingly, to evaluate many potential risk factors, the authors undertook a prospective, multicenter, epidemiologic study. METHODS: On a voluntary basis, anesthetists at 15 participating centers forwarded a data sheet on patients who had spinal anesthesia to a research nurse blinded to the details of anesthesia and surgery. A subset was randomly selected for follow-up. The pressure [corrected] of transient neurologic symptoms, defined as leg or buttock pain, was the principal outcome variable. Logistic regression was used to control for potential confounders, and adjusted odds ratios and confidence intervals were used to estimate relative risk. RESULTS: During a 14-month period, 1,863 patients were studied, of whom 47% received lidocaine, 40% bupivacaine, and 13% tetracaine. Patients given lidocaine were at higher risk for symptoms compared with those receiving bupivacaine (relative risk, 5.1; 95% CI, 2.5 to 10.2) or tetracaine (relative risk, 3.2; 95% CI, 1.04 to 9.84). For patients who received lidocaine, the relative risk of transient neurologic symptoms was 2.6 (95% CI, 1.5 to 4.5) with the lithotomy position compared with other positions, 3.6 (95% CI, 1.9 to 6.8), for outpatients compared with inpatients, and 1.6 (95% CI, 1 to 2.5) for obese (body mass index >30) compared with nonobese patients. CONCLUSIONS: These results indicate that transient neurologic symptoms commonly follow lidocaine spinal anesthesia but are relatively uncommon with bupivacaine or tetracaine. The data identify lithotomy position and outpatient status as important risk factors in patients who receive lidocaine. Among other factors postulated to increase risk, obesity had an effect of borderline statistical significance, whereas age, sex, history of back pain, needle type, and lidocaine dose and concentration failed to affect risk.

Adult↗

PubMed1998

Effect of intravenous anesthetics on spontaneous and endotoxin-stimulated cytokine response in cultured human whole blood.

BACKGROUND: Various anesthetics have been suggested to interfere with the immune system. The ability of leukocytes to express surface receptors and mediators is fundamental to a successful host defense. Therefore, the effects of intravenous anesthetics on cytokine release by leukocytes and expression of surface molecules known to modulate this response were determined. METHODS: Concentration-dependent effects of thiopentone, etomidate, propofol, ketamine, midazolam, and fentanyl on spontaneous and endotoxin (lipopolysaccharide; 1 microg/ml)-stimulated cytokine release were studied in whole blood from volunteers (n = 6) cultured for 25 h. In addition, expression of the lipopolysaccharide-recognition molecule CD14 and the major histocompatibility complex class II molecule human leukocyte locus A system-DR (HLA-DR) on monocytes were assessed using flow cytometry. RESULTS: All anesthetics studied elicited only minor effects on spontaneous cytokine release even at pharmacologic concentrations. However, expression density of CD14 was reduced in the presence of thiopentone, etomidate, and propofol, whereas HLA-DR was unaffected. Lipopolysaccharide-stimulated tumor necrosis factor response was inhibited by thiopentone (12.8% [median]; 7.6-18.8 [25-75 percentile]) of control, and ketamine (46.4% [median]; 44.4-56.4 [25-75 percentile]), at pharmacologic concentrations, whereas it was augmented even in the presence of low concentrations of propofol (172.3% [median]; 120.5-200.7 [25-75 percentile]). Ketamine additionally decreased the concentration of interleukin (IL)-1beta (14.8% [median]; 12.0-18.0 [25-75 percentile]). Release of IL-1 receptor antagonist (IL-1ra) was inhibited by thiopentone, etomidate, and propofol, whereas the same anesthetics increased IL-10 concentration simultaneously. Midazolam and fentanyl did not alter the concentrations of any cytokine. CONCLUSIONS: These results suggest a complex modulation of the cytokine response by the studied anesthetics in cultured whole blood. Although effects on spontaneous cytokine release by leukocytes were negligible, some anesthetics affected their ability to respond to lipopolysaccharide.

Anesthetics, Intravenous↗

PubMed1998

Molecular mass determination for prostate-specific antigen and alpha 1-antichymotrypsin complexed in vitro.

The results from molecular mass determinations and amino acid analyses for prostate-specific antigen (PSA), alpha 1-antichymotrypsin (ACT) and PSA-ACT complexed in vitro are reported. Molecular masses for two separate PSA-ACT lots were determined by matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS) coupled to a time-of-flight (TOF) detector. Interestingly, both PSA-ACT lots contained two predominant protein species: 78,095 +/- 138 Da (approx. 67% of total protein) and 82,519 +/- 104 Da. Because a heterogneous population was observed and the masses were less than expected on the basis of less sensitive techniques, molecular masses for the individual PSA and ACT components were determined. As expected, PSA possessed a single molecular mass (27,755.8 Da). Each ACT raw material lot, however, also contained two predominant species: 55,106 +/- 111 and 51,414 +/- 32 Da. To assess the amino acid composition, each PSA, ACT and PSA-ACT lot was subjected to acid hydrolysis for 24, 48 and 72 h followed by amino acid analysis. Experimental results, expressed as mole percentages for each measurable residue and the number of residues per mole of protein, were compared with both the predicted and previously published values and were as expected. These more accurate molecular mass values for ACT and purified PSA-ACT complex should be considered in preparing and characterizing international standard preparations.

Amino Acids↗

PubMed1997

Structural probing and mutagenic analysis of the stem-loop required for Escherichia coli dnaX ribosomal frameshifting: programmed efficiency of 50%.

Three elements are crucial for the programmed frameshifting in translation of dnaX mRNA: a Shine-Dalgarno (SD)-like sequence, a double-shift site, and a 3' structure. The conformation of the mRNA containing these three elements was investigated using chemical and enzymatic probes. The probing data show that the structure is a specific stem-loop. The bottom half of the stem is more stable than the top half of the stem. The function of the stem-loop was further investigated by mutagenic analysis. Reducing the stability of the bottom half of the stem strongly effects frameshifting levels, whereas similar changes in the top half are not as effective. Stabilizing the top half of the stem gives increased frameshifting beyond the WT efficiency. The identity of the primary RNA sequence in the stem-loop is unimportant, provided that the overall structure is maintained. The calculated stabilities of the variant stem-loop structures correlate with frameshifting efficiency. The SD-interaction and the stem-loop element act independently to increase frameshifting in dnaX.

Bacterial Proteins↗

PubMed1997

[General practitioners' handling of patients with dyspepsia].

The handling of patients with dyspepsia by 102 general practitioners was investigated prospectively using a standardised application form for gastroscopy followed by a questionnaire to the practitioners. A mean of 5.3 indications were stated among 16 performed referral possibilities in 143 applications. Referral because of long-standing symptoms, ineffective treatment trial and atypical dyspepsia were more often stated than certain important risk factors (high age, NSAID-ingestion etc.). In 23% of cases no specific suspicion of organic disease was stated. The questionnaire was answered by 85%. More than 90% of doctors would use a treatment trial before further investigation of dyspeptic patients with first time consultation. A wide variation of medical empirical treatment was indicated. The practitioners wished to retain the open access model for referring, but a great majority desired practical guidelines for the handling of dyspeptic patients. This study confirms the relevance of such guidelines to improve present practice.

Denmark↗

PubMed1997

The complex between urokinase plasminogen activator and its type-1 inhibitor in breast cancer extracts quantitated by ELISA.

ELISAs for urokinase plasminogen activator (uPA) and plasminogen activator inhibitor type-1 (PAI-1) have shown that tumor levels of these molecules are prognostic parameters in breast cancer as well as other types of cancer. These ELISAs measure the total amount of the given component, including preforms, active, inactive, and complex-bound forms. However, the amount of the active forms of a component may more closely reflect the ongoing level of proteolytic activity and thereby be particularly related to prognosis. Since the inactive complex between uPA and PAI-1 can only be formed the active forms of the individual components, we have developed a sensitive and specific uPA:PAI-1 complex ELISA consisting of a sandwich format with two monoclonal antibodies (MAbs) against PAI-1 as capture antibodies and three biotinylated MAbs against uPA as detector antibodies. The data were collected as kinetic measurements of bound alkaline phosphatase activity. A standard of uPA:PAI-1 complex could be specifically measured in the assay with a detection limit of 8 pg/ml and a linear relationship between signal and complex concentration up to 4 ng/ml. Neither free uPA nor free PAI-1 were detected by this assay and the addition to the internal standard of free PAI-1 in amounts up to 20 ng/ml or uPA did not reduce the detection of complex by the assay. This ELISA was applied to extracts from 20 individual breast cancers. Each tumor was extracted in two different buffers and the median concentration of uPA:PAI-1 complex in the optimal extraction buffer was 0.8 ng/mg protein, range 0.4-2.8 ng/mg protein. Extraction of the tumor tissue at a low pH prevented de novo formation of complex from free uPA and PAI-1 in the tissue without destabilizing preformed uPA:PAI-1 complex. During incubation of the assay plate at neutral pH further uPA:PAI-1 complex formation from free components in the extracts was blocked by p-nitrophenyl guanidinobenzoate (NPGB). Thus, the present assay selectively quantifies preformed complex in tumor extracts and will enable us, for the first time, to evaluate the potential prognostic value of the uPA:PAI-1 complex in cancer.

Animals↗

PubMed1997

Candida albicans morphogenesis is influenced by estrogen.

Conversion of Candida albicans from yeast to mycelial growth is believed to be associated with the organism's virulence. We investigated the role of mammalian hormones in initiating this transformation. Three clinical isolates of Candida albicans were tested for their ability to produce germ tubes under various conditions. Controlled hormonal conditions were provided by stripping rabbit serum with activated charcoal. Steroid compounds under investigation were added back to the stripped serum and yeast were inoculated into the test materials. Microscopic counts of germinated versus ungerminated cells were used as an indicator of morphogenic transformation. The percent of yeast cells germinating was profoundly reduced in stripped compared to unstripped serum. The addition of 1 microM estradiol, cholesterol or testosterone only slightly increased levels of germination above that seen in controls. Estradiol at concentrations 100 times less, however, proved a strong inducer of germination. Cholesterol did not synergize germination when combined with estradiol and the alpha isomer of estradiol had almost no activity as an inducer of morphogenic change in Candida albicans. We conclude that beta estradiol was a morphogenic inducer in three clinical isolates of Candida albicans but only at concentrations typical in vivo.

Animals↗

PubMed1997

Effect of alveolar hypoxia on segmental pulmonary vascular resistance and lung fluid balance in dogs.

In a biventricular bypass preparation with constant-flow perfusion, pulmonary arterial pressure (Ppa), average pulmonary capillary pressure (Ppc), venous pressure (Pv), extravascular lung water volume (EVWd) and capillary permeability-surface area product for urea (PS) were determined in control animals and in animals subjected to alveolar hypoxia. During hypoxia, Ppa increased in a biphasic manner, the site of hypoxic pulmonary vasoconstriction being located in the arterial upstream segment. At baseline, Ppc values were identical in control and experimental animals (3.4 +/- 0.4 vs. 3.6 +/- 0.2 mmHg). During 150 min of airway hypoxia, the rise in Ppc (5.1 +/- 0.3 mmHg) did not exceed the rise in Ppc (4.9 +/- 0.5 mmHg) recorded in control animals at same time interval during normoxic ventilation. EVWd increased during hypoxia to values significantly higher than those obtained in control animals (0.559 +/- 0.036 vs. 0.466 +/- 0.027 mL water g-1 lung). PS remained unchanged at baseline level throughout experiments in both groups of animals. Present data suggest that lung oedema formation during alveolar hypoxia may be caused by increased transcapillary fluid loss preferentially through transcellular hydraulic pathways in capillary endothelial cells.

Animals↗

PubMed1997

Determination of the exocrine pancreatic function with the NBT-PABA test using a novel dual isotope technique and gas chromatography-mass spectrometry.

We describe a tubeless test of exocrine pancreatic function based on a new dual isotope technique, using N-benzoyl-L-tyrosyl-p-aminobenzoic acid (NBT-PABA) as a substrate for intestinal chymotrypsin activity and the stable isotope, 13C-PABA as marker. Gas chromatography-mass spectrometry (GC-MS) was used for the quantification of PABA and 13C-PABA in blood. The method involves hydrolysis, extractions, separation by HPLC, and methyl ester formation of the test substances before GC-MS analysis. The test is precise and shows good separation of healthy volunteers from patients with pancreatic insufficiency. The PABA/13C-PABA ratios in serum after 1.5 h were 2.64 +/- 0.14 (mean +/- SEM) in 10 healthy volunteers and 1.26 +/- 0.22 in 10 patients with exocrine pancreatic insufficiency. We present a sensitive and specific assay, which is free of analytical interference and radiation hazards and, additionally, it illuminates extrapancreatic pharmacokinetic conditions. This test can eliminate the need for duodenal intubation, which makes it very acceptable to the patients.

4-Aminobenzoic Acid↗

PubMed1997

Double-homograft repair of truncus arteriosus with severe truncal valve dysfunction.

An infant with truncus arteriosus and severe dysfunction of the truncal valve including both stenosis and insufficiency successfully underwent primary repair. This included the insertion of two separate valved homograft conduits. Early outcome has been excellent and the patient is doing well after 6 months with only echocardiographic evidence of mild aortic valve regurgitation. Double-homograft repair is a realistic option in cases of truncus arteriosus with severe malformation of the truncal valve.

Echocardiography, Doppler↗