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K Olsen

Publications and source records attributed to K Olsen.

At least 37 records · Page 2Linked to original sources
PubMed1999

Pharmacodynamics of trovafloxacin in experimental pneumococcal meningitis: basis for dosage selection in children with meningitis.

Trovafloxacin is a recently approved fluoroquinolone with excellent activity against gram-positive and gram-negative organisms that offers a potential alternative for treatment of beta-lactam-resistant pneumococcal meningitis. Using the rabbit meningitis model, we sought to characterize the pharmacodynamic properties of trovafloxacin in the cerebrospinal fluid (CSF). Animals were given single doses of trovafloxacin of 10, 15, 20 or 30 mg/kg; 1 h after Infusion mean CSF concentrations were 0.59+/-0.18, 0.74+/-0.14, 1.12+/-0.12 and 1.07+/-0.35 mg/L, respectively. The bacterial killing rate Increased with increasing dosages of trovafloxacin, indicating that its activity is concentration dependent. All three pharmacodynamic Indices (area under the concentration curve (AUC)/MBC, peak concentration (Cmax)/MBC, and time above MBC (T > MBC)) correlated with bacterial killing; however, AUC/MBC correlated best (r = 0.71). In a second experiment we found comparable bacterial killing with multiple doses of trovafloxacin given either every serum half-life or every two serum half-lives. In both experiments bacterial regrowth occurred when the concentration of trovafloxacin in CSF fell below the MBC. These data have been used in formulating an appropriate regimen for trovafloxacin treatment of bacterial meningitis in children.

Animals↗
PubMed1999

Chloramphenicol pharmacokinetics in infants less than three months of age in the Philippines and The Gambia.

BACKGROUND: The broad antimicrobial spectrum and affordable price of chloramphenicol make it an attractive first line treatment option for children with severe illnesses in developing countries. Little is known, however, about its pharmacokinetics in young infants in these settings. METHODS: We studied infants younger than 3 months of age hospitalized in Manila, Philippines and The Gambia with possible severe bacterial infections likely to benefit from treatment with chloramphenicol. Infants in the first week of life received intramuscular doses of 25 mg/kg chloramphenicol once daily, twice daily in the second through fourth week of life and three times daily from 5 to 12 weeks of age. Blood samples were taken at 0.5, 1, 2 and 3 h after the first dose, 1 h before the second dose and before the repetition doses on subsequent days. In the Philippines a second group of infants was treated with oral chloramphenicol according to the same dosage schedule. RESULTS: Thirty-eight infants received intramuscular chloramphenicol, and 20 received oral drug. Intramuscular administration resulted in therapeutic concentrations (10 to 25 microg/ml) in 73 to 86% of children in each of the three age groups in the first 6 h and in 50 to 80% on Days 2 and 3. Between 33 and 38% of children had potentially toxic values on Days 2 and 3. In contrast, after oral administration, only about one-half of the children reached therapeutic values in serum at any time up to Day 3 after start of treatment. CONCLUSIONS: Intramuscular chloramphenicol can be used as a second line drug for the treatment of severe infections in infants younger than 90 days of age, where third generation cephalosporins are not available. It quickly achieves therapeutic values in a high proportion of children. However, severe infections should not be treated with oral chloramphenicol in this age group, because therapeutic serum concentrations were inconsistently achieved.

Administration, Oral↗
PubMed1998

Mycoplasma pneumoniae pneumonia in a mouse model.

To investigate the pathogenesis of acute Mycoplasma pneumoniae infection, BALB/c mice were anesthetized with metofane, and M. pneumoniae was introduced intranasally on days 0, 1, and 2. Mice were sacrificed on days 0-15. A histopathologic scoring system defined inflammatory changes in the lungs on a scale of 0-26 (least to most severe). Broth cultures were positive for all nasal passage and bronchoalveolar lavage (BAL) specimens. Histopathologic scores ranged from 0 to 21. The mean log10 (cfu/mL) were 4.1-6.4 on days 1-10 and >/=1.7 on days 13-15 for nasal passage and BAL specimens. Serum polymerase chain reaction was negative. ELISA for serum IgM and immunoblots for M. pneumoniae antibody were positive in 21 (62%) of 34 and 33 (97%) of 34 infected animals, respectively, at days 8-15. ELISA for IgG antibody was negative. This mouse pneumonia model can be used to study the immunologic and therapeutic responses to acute M. pneumoniae infection.

Animals↗
PubMed1998

A role for histamine and substance P in immediate allergic responses in guinea pig airways: characterization of MDL 108,207DA, a dual H1/NK-1 receptor antagonist.

BACKGROUND: Histamine is a critical mediator of immediate hypersensitivity reactions. Sensory neuropeptides, such as substance P (SP), may also contribute to acute inflammatory responses. A compound which antagonizes both H1 and NK-1 receptors, such as MDL 108,207DA, may present a significant therapeutic advantage over pure antihistamines. METHODS: The binding affinity of MDL 108,207DA for H1 and NK-1 receptors was evaluated and its potency of antagonism evaluated in vitro. The in vivo antagonism of SP- or histamine-induced microvascular leakage in guinea pig airways was examined. A role for these mediators in antigen-induced microvascular leakage in ovalbumin-sensitized guinea pig airways was examined using MDL 108,207DA as well as the NK-1-selective antagonist FK888 and the H1-selective antagonist pyrilamine alone or in combination. RESULTS: The affinity of MDL 108,207DA for H1 and NK-1 receptors is similar to that of receptor-selective antagonists. The compound inhibits both receptors in vitro and in vivo with comparable potencies for each. The efficacy of FK888 in combination with pyrilamine and MDL 108,207DA on antigen-induced microvascular leakage in sensitized guinea pig airways supports a role for both SP and histamine in early allergic responses. CONCLUSION: The contribution of both SP and histamine to immediate hypersensitivity reactions supports the utility of NK-1 and H1 receptor antagonist therapy. MDL 108,207DA incorporates both activities into the same compound and, as a result, may be useful in the treatment of allergic diseases.

Animals↗
PubMed1998

[Importance of Mycoplasma pneumoniae and Chlamydia pneumoniae in children with community-acquired pneumonia].

OBJECTIVES: To determine the importance of Mycoplasma pneumoniae and Chlamydia pneumoniae in community-acquired pneumonia (CAP) of children from different latitudes and to compare clinical outcome using azithromycin (AZM) versus either amoxicillin-clavulanate (A-C) or erythromycin estolate (EE). METHODS: Ambulatory patients with CAP were identified at either the Children's Medical Center of Dallas, Texas or the Hospital del Niño of Panama City, Panama. Children 6 months to 15 years of age were enrolled and randomized to receive either AZM for 5 days or a 10 day course of either A-C or EE, for those younger or older than 5 years of age, respectively. Mycoplasma pneumoniae and C. pneumoniae were identified by measuring acute and convalescent serum antibody titers and by performing nasopharyngeal (NP) and oropharyngeal (OP) swabs for culture and polymerase chain reaction (PCR) testing. RESULTS: Overall 335 patients (168 in Dallas and 167 in Panama) were evaluated from February 1996 through December 1997. Acute M. pneumoniae infection was detected in 12 (7%) patients each in Dallas and Panama. Acute C. pneumoniae infection was observed in 10 (6%) children at each site. Infection caused by these "atypical" microorganisms occurred more frequently in children older than 5 years of age (23% vs 9%, P = 0.001, RR 2.5, 95% CI 1.4-4.3). No distinctive pattern of clinical or radiologic abnormalities was seen in relation to etiology. Clinical cure was achieved in 43 of 44 children infected by these bacteria regardless of treatment assignment. CONCLUSION: Mycoplasma pneumoniae and C. pneumoniae are common etiologic agents of CAP in older children from different latitudes. Children with CAP present with similar clinical and radiologic findings to those caused by other etiologic agents. Outcome was excellent for the three treatment regimens studied.

Adolescent↗
PubMed1997

Choosing sample volume to achieve maximum detection sensitivity and resolution with high-performance liquid chromatography columns of 1.0, 2.1 and 4.6 mm I.D.

The relationship between sample volume and the chromatographic performance factors of detection sensitivity and resolution were explored for high-performance liquid chromatography (HPLC) columns of 1.0, 2.1 and 4.6 mm I.D. Performance was evaluated for isocratic and gradient elution in systems having low, intermediate and high extracolumn dispersion. Sample volumes ranged from 0.4 microliter to 2 ml. This paper provides guideline for selecting sample injection parameters so that the performance of microbore columns is not needlessly sacrificed by using too small or too large a sample volume. The guidelines are extracted from the works of others and are modified by our own experimental results. Comments are also made on the relative merits of various injection techniques.

Chromatography, High Pressure Liquid↗
PubMed1997

Frequent allelic losses on chromosome 13q in human male breast carcinomas.

Loss of genetic material on chromosomes 13q and 17 has been suggested to be of importance in the initiation and progression of female breast cancer, but their involvement is less well illustrated in male breast carcinomas. The present study was designed to investigate the incidence of allelic loss and microsatellite instability for chromosomes 13q, 17p and 17q in 13 sporadic male breast carcinomas using matched normal-tumour DNA samples and seven polymorphic microsatellite markers. Genetic imbalance was found in one or more informative markers in 85% of the patients, with more frequent loss of heterozygosity and microsatellite instability at loci on chromosome 13q. Thus, a high incidence of allelic losses was observed at the retinoblastoma gene (4/6) and likewise at the D13S263 locus (7/12), which also exhibited the highest frequency of microsatellite instability. The intragenic microsatellite in intron 1 of the TP53 gene on chromosome 17p revealed loss of heterozygosity in 3 of 8 informative patients. The investigated proximal region of chromosome 13q is postulated to harbour several potential tumour suppressor genes associated with female breast cancer. The high incidence of allelic losses at the D13S263 microsatellite, located distal to both the BRCA2 and the Brush-1 loci but proximal to the retinoblastoma gene, possibly indicates the presence of an additional tumour suppressor gene which may be involved in male breast carcinomas. However, this hypothesis needs verification in an extended study of male breast carcinomas.

Breast Neoplasms, Male↗
PubMed1997

The effect of interleukin-10 on meningeal inflammation in experimental bacterial meningitis.

Interleukin-10 (IL-10) is a cytokine with antiinflammatory effects. In a rabbit model of meningitis, IL-10 was given intracisternally or intravenously to evaluate the impact on inflammation induced by lipooligosaccharide (LOS), Haemophilus influenzae type b (Hib), or Listeria monocytogenes. Intracisternal IL-10 in concentrations >1 microg significantly reduced tumor necrosis factor-alpha (TNF-alpha) and lactate values in cerebrospinal fluid (CSF). Intravenous IL-10 (1 mg/kg) in two doses after intracisternal LOS significantly reduced CSF TNF-alpha and lactate. When Hib was used, animals were treated with ceftriaxone and dexamethasone with or without IL-10 (1 mg/kg). TNF-alpha was significantly reduced in animals treated with IL-10, dexamethasone, or both compared with levels in rabbits receiving ceftriaxone alone. Comparable results were obtained when L. monocytogenes was inoculated and animals were treated with ampicillin with or without IL-10, dexamethasone, or nothing. In conclusion, IL-10 modulates CSF TNF-alpha concentrations in experimental LOS, Hib, or L. monocytogenes meningitis. The maximal inhibitory effect was seen when IL-10 and dexamethasone were combined.

Animals↗
PubMed1997

Pharmacodynamics and bactericidal activity of ceftriaxone therapy in experimental cephalosporin-resistant pneumococcal meningitis.

Adequate concentrations of beta-lactam antibiotics in cerebrospinal fluid (CSF) are difficult to achieve for meningitis caused by drug-resistant Streptococcus pneumoniae. Ceftriaxone in dosages of 150 or 400 mg/kg of body weight per day, given in one or two doses, was used for the treatment of experimental highly cephalosporin-resistant (MIC and MBC, 4 microg/ml) pneumococcal meningitis. The bacterial killing rate (delta log10 CFU per milliliter per hour) and pharmacokinetic indices, including percentage of time the antibiotic concentration exceeded the MBC during a 24-h period (T>MBC), CSF peak concentration above the MBC, and area under the concentration-time curve from 0 to 24 h above MBC, were measured and correlated. By multiple stepwise regression, only T>MBC independently predicted the bacterial killing rate. There was a direct linear correlation between T>MBC in CSF and the bacterial killing rate during the first 24 h of therapy (r = 0.87; P = 0.004). Sterilization of CSF was achieved only when the T>MBC was 95 to 100%. In the first 24 h, the 200-mg/kg/12-h regimen, compared with the 400-mg/kg/24-h regimen, was associated with a greater T>MBC (87% +/- 10% versus 60% +/- 22%; P = 0.03) and greater bacterial killing rate (0.2 +/- 0.04 versus 0.13 +/- 0.07; P = 0.003), confirming that ceftriaxone exhibits time-dependent bactericidal activity. After 24 h, the T>MBC and the CSF sterilization rates were similar whether ceftriaxone was given once or twice daily.

Animals↗
PubMed1996

Substrate binding mechanism of Glu180-->Gln, Asp176-->Asn, and wild-type glucoamylases from Aspergillus niger.

Glucoamylase (1,4-alpha-glucan glucohydrolase, EC 3.2.1.3) from Aspergillus, of which the 3D structure is known, releases beta-D-glucose from the non-reducing ends of starch and other related oligo and polysaccharides, cleaving the alpha-1,4-bond positioned between subsites 1 and 2 in the enzyme-substrate complex. The presteady and steady state kinetics of two of the existing mutants, Glu180-->Gln and Asp176-->Asn, are presented here. The kinetic results are analyzed according to two reaction models: One suggested previously [Olsen, K., Svensson, B., & Christensen, U. (1992) Eur. J. Biochem. 209, 777-784], which contains three consecutive steps of the reaction, and one generally accepted and used in calculations of subsite energies [Hiromi, K. (1970) Biochem. Biophys. Res. Commun. 40, 1-6], which assumes important non-productive binding and identical values of the intrinsic catalytic constant independent of the chain length of the substrate. It is found that glucoamylase shows kinetics in accordance with a consecutive three-step mechanism, in which the formation of the Michaelis complex occurs in two steps and is followed by a slow catalytic step and fast dissociation of the products with no accumulation of enzyme-product complexes. The kinetics, however, are not in accordance with the model generally used in subsite energy calculations. Thus the kinetic model on which very low values of subsite 1 and high values of subsite 2 interaction energies have been based is not correct. A greater importance of subsite 1 interactions than has hitherto been anticipated is indicated. The results of the Glu180-->Gln mutant show weak overall binding, which stems from large effects on the formation of the Michaelis complex in the second step of the reaction, but no or rather small effects on the initial association of enzyme and substrate, except for maltose. The mutant further shows effective catalysis. A hydrogen bond of the side chain carboxylate of Glu180 with the 2-OH of the sugar ring at subsite 2 is an expected important interaction of the Michaelis complex, as seen from the 3D structures of stabile enzyme-inhibitor complexes. Apparently this bond is established in the second reaction step. It is indicated that subsite 1 and 3 interactions to a great extent govern the initial association. In accordance with a dynamic role of Glu180, structural energy minimization calculations show a flexibility of the gamma-carboxylate of Glu180. The side chain of Asp176 participates in a hydrogen-bonding network also involving the backbone of Glu180 and Glu179, the catalytic acid. Compared with the wild-type enzyme, the Asp176-->Asn mutant shows no significant changes in binding. The catalytic rate is, however, markedly reduced. Apparently changes in the hydrogen bonding network of Asp176 are of importance in the rate-determining catalytic step, but not in the substrate binding steps. Structural energy minimization calculations on the Asp176-->Asn mutant, however, do not confirm this assumption.

Asparagine↗
PubMed1996

Cerebrospinal fluid values in the term neonate.

BACKGROUND: Cerebrospinal fluid (CSF) values in the noninfected neonate are not well-delineated. Studies analyzing these values are inconsistent in the criteria used to define the noninfected population. The purpose of our study was to examine CSF values in neonates in the first 30 days of life in whom infection was more thoroughly excluded than in previous reports. Stringent inclusion criteria defined the noninfected population, and the recently available polymerase chain reaction (PCR) for enteroviruses was used in addition to cultures to help exclude viral disease. Results were also stratified by age in weeks to evaluate for any variability that occurs in CSF values during the first month of life. METHODS: Neonates were selected from subjects enrolled in two studies on aseptic meningitis. Noninfected infants were identified by the following criteria: (1) atraumatic lumbar puncture (< or = 1000 red blood cells/mm3); (2) no antibiotic therapy before lumbar puncture; (3) sterile blood, CSF and urine bacterial cultures; (4) negative CSF viral culture; and (5) negative CSF PCR for enteroviruses. RESULTS: The mean +/- SD total CSF white blood cell count for 108 noninfected neonates was 7.3 +/- 14/mm3 (95% confidence interval 6.6 to 8.0/mm3) with a median of 4/mm3 and a range of 0 to 130/mm3. There were no significant differences in the mean CSF white blood cell counts among age categories. CONCLUSIONS: The application of stringent inclusion criteria and the use of the PCR yielded a population of infants that better represents the noninfected neonate than earlier reports. These values can be used for reference in evaluating the febrile or ill neonate.

Age Factors↗
PubMed1995

Phenytoin free fraction determination: comparison of an improved direct serum injection high-performance liquid chromatographic method to ultrafiltration coupled with fluorescence polarization immunoassay.

Recent developments in restricted-access media (RAM) liquid chromatography make the simultaneous determination of total and free phenytoin concentrations possible by direct injection of drug-containing serum samples. A comparison of phenytoin free fraction determination by ultrafiltration coupled with fluorescence polarization immunoassay (TDX) to an improved direct injection RAM-HPLC method is presented. Our improved method differs from those previously reported with regard to column type, mobile-phase composition, and column temperature. Replicate samples analyzed by each method yielded similar values for serum phenytoin free fraction.

Anticonvulsants↗
PubMed1995

Stopped-flow kinetic studies of the reaction of barley alpha-amylase/subtilisin inhibitor and the high pI barley alpha-amylase.

The interaction of alpha-amylase/subtilisin inhibitor (BASI) from barley seeds and the high pI barley alpha-amylase (AMY2) de novo synthesized during seed germination, has been studied at pH 8.0, 25 degrees C, using stopped-flow fluorescence spectroscopy, equilibrium fluorescence titration and kinetic analysis of the displacement of BASI from the BASI-AMY2 complex by the substrate blue starch. The results are in accordance with a two-step reaction model: [formula: see text] The resulting values of the kinetic parameters were: k2/K1 = (1.0 +/- 0.2) x 10(6) M-1.s-1, K1 = 0.4 +/- 0.21 mM, k2 = 320 +/- 150 s-1, k-2 = (7.2 +/- 0.6) x 10(-5)s-1, and the overall dissociation constant Kd = (0.7 +/- 0.1) x 10(-10) M. BASI thus is best characterized as a fast reacting, tight-binding inhibitor of AMY2.

Hordeum↗
PubMed1995

Serial killing by cytotoxic T lymphocytes: T cell receptor triggers degranulation, re-filling of the lytic granules and secretion of lytic proteins via a non-granule pathway.

CD8+ cytotoxic T lymphocyte (CTL) clones begin to synthesize the lytic proteins granzyme A, granzyme B and perforin after stimulation with allogeneic target cells. The lytic proteins are stored in the secretory granules which are released after cross-linking of the T cell receptor (TcR) upon target cell recognition. During lytic granule biogenesis granzyme A protein synthesis can be detected between 2 and 10 days after allogeneic stimulation of the CTL. Although granzyme A is stored in the lytic granules over this period, the majority of granzyme A synthesized is secreted directly from the CTL. TcR triggering of degranulation also results in new synthesis of the lytic proteins, which can be inhibited by cycloheximide (CHX). Some of the newly synthesized lytic proteins can be stored in the cell and refill the granules. But up to one third of granzymes A and B can be secreted directly from the CTL via the constitutive secretory pathway as shown by granzyme A enzymatic activity and immunoblots of secreted granzyme B, where one third of the protein fails to acquire the granule targeting signal. Perforin is also secreted via the constitutive pathway, both from the natural killer cell line, YT, and from CTL clones after TcR cross-linking. Constitutive secretion of the lytic proteins can be blocked by both CHX and brefeldin A (BFA). While BFA does not affect the directional killing of recognized targets, it abrogates bystander killing, indicating that bystander killing arises from newly synthesized lytic proteins delivered via a non-granule route. These results demonstrate that the perforin/granzyme-mediated lytic pathway can be maintained while CTL kill multiple targets. We show that CTL not only re-fill their granules during killing, but also secrete lytic proteins via a non-granule-mediated pathway.

Biological Transport↗
PubMed1995

p53 as a prognostic factor in stage I breast cancer. South-East Sweden Breast Cancer Group.

Accumulation of the tumour-suppressor protein p53 in breast cancer is associated with several prognostic factors that indicate an aggressive, rapidly proliferating tumour with an unstable genome. To assess p53 accumulation in stage I breast cancer and to evaluate the prognostic value of both nuclear and cytoplasmic p53, 205 patients with node-negative breast cancer and tumour size less than or equal to 20 mm were examined. Immunohistochemistry was performed on frozen sections with the monoclonal antibodies PAb 1801 and DO1. Cellular p53 accumulation, within either the nucleus or the cytoplasm or in both, showed the same association with different pathobiological variables as nuclear accumulation alone. Eleven per cent of the tumours showed strong nuclear accumulation and were significantly correlated to age under 50 years, negative oestrogen receptor status, DNA aneuploidy, high S-phase fraction, high pathological grade and poor prognosis. The distant recurrence rate ratio was 6.2 (P = 0.002). It is thus concluded that p53 accumulation is of prognostic value in early stage breast cancer.

Breast Neoplasms↗