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Biomedical subjects

N Muller

Publications and source records attributed to N Muller.

At least 37 records · Page 2Linked to original sources
PubMed1995

Cryptogenic organizing pneumonia. A report of 25 cases and a review of the literature.

Cryptogenic organizing pneumonia (COP), also known as bronchiolitis obliterans organizing pneumonia (BOOP), is an uncommon lung disease characterized by the presence of granulation tissue within the alveolar ducts and alveoli. Because of the limited published literature on this topic and limited information on outcome we reviewed our own experience over an 8-year period and also critically evaluated the literature. We reviewed all cases of COP diagnosed from 1985 through 1992 at Vancouver General Hospital: 25 patients (14 male, 11 female) aged 20-77 years (mean, 49 yr, SD +/- 17 yr). Nine patients had myeloproliferative disorder, including 6 who had allogenic bone marrow transplants; 2 patients had connective tissue disease; and 14 patients had no underlying disease (idiopathic). Data retrieved retrospectively from clinical records included demographics, risk factors, symptoms, chest radiographs, computerized tomograms, lung function tests, therapy prescribed, and response to therapy. Symptoms included dyspnea and cough (n = 15) (60%), cough only (n = 10) (40%), and fever (n = 15) (60%). Twenty-two patients were diagnosed by open lung biopsy and 3 by transbronchial biopsy. Lung imaging showed bilateral patchy airspace consolidation or nodular opacities as the main finding in 22 patients. Pulmonary function tests showed a combined restrictive and obstructive pattern. All patients received prednisone therapy except 1 patient whose idiopathic findings resolved completely with minimal treatment. Eight patients died, including 4 of the 9 patients with myeloproliferative disorder--2 from a combination of respiratory failure due to COP and graft-versus-host disease. One of 2 patients with connective tissue disease died, and 3 of 14 patients with idiopathic COP died. COP is an uncommon condition but should be considered in patients with bilateral airspace disease, especially those who fail to respond to antibiotics for presumed pneumonia. Although pulmonary function tests and CT scan findings in conjunction with the clinical features usually suggest the diagnosis, definite confirmation usually requires either open lung biopsy or transbronchial biopsy. Histologic confirmation of the diagnosis is particularly warranted as therapy with corticosteroids is usually needed for a number of months. The prognosis is excellent with idiopathic cases but more guarded especially when COP is associated with lymphoproliferative or connective tissue disease.

Adrenal Cortex Hormones↗
PubMed1994

Anti-inflammatory properties of IL-1 in carrageenan-induced paw oedema.

To evaluate any inhibitory effect of a single dose of human recombinant interleukin-1 beta (hrIL-1 beta) on the severity of carrageenan-induced oedema in rats (a commonly used model of acute inflammation), we first injected 0.1 ml of carrageenan (0.2%, 0.5%, or 2%) to induce mild, moderate, or severe inflammation, respectively into the right rear footpad. Then we promptly injected the interleukin (0.02, 0.2, or 2 micrograms) subcutaneously into the flank. The initial rapid increase in volume of the injected paw (within 2 h of the subplantar injection) was independent of the dose of carrageenan, whereas the increase in volume by 6 to 10 h was dose-dependent. All doses of HrIL-1 beta inhibited the carrageenan-induced swelling at the 6th hour. In the moderate and severe carrageenan-induced oedemas, the higher dose of HrIL-1 beta induced a delayed inflammation peaking at 10 h instead at 6 h.

Animals↗
PubMed1994

Representation of affinity in the case of co-operativity in protein-ligand binding.

We have already proposed a "Global Association Function" to represent the global affinity of proteins to a drug; it was first applied in the case of independent binding sites. In this paper, we show that this same function can also be used to assess interactions between sites by varying the number of interacting sites and their co-operativity level. The resulting curves in two application cases are given together with the corresponding Scatchard plot: i) in a system with one single class of identical and interacting sites, ii) in a system with two classes of sites in which either primary or secondary are interacting; unexpectedly, in this latter case we also observed that sometimes positive co-operativity occasionally resulted in a concave-up Scatchard plot which is unusually admitted. In addition, as described in one example, our function is assumption free; this might be an advantage over usual methods, such as discrete parameter methods, because they require additional and empirical hypotheses on their related binding model.

Binding Sites↗
PubMed1994

Binding sites of fluorescent probes on human serum albumin.

Human serum albumin is known to have two major and selective drug binding sites, termed sites I and II. The fluorescent probes, dansylamide and dansylsarcosine selectively interact with sites I and II, respectively. However, the binding site of the fluorescent probe dansylglycine on human serum albumin is not clear from the literature. This study investigated whether dansylglycine interacts tightly with site I or II. Spectrofluorimetric titrations (quenching and complex) and circular dichroism measurements were performed to determine the binding characteristics of dansylglycine to human serum albumin. Modification in probe fluorescence was described by fluorescence titrations to be a result of competitive displacement by ligands. The pattern of displacement of this probe by several ligands whose primary binding sites are exactly known, enabled the identification of its specific binding site. The fluorescence of dansylglycine is only extensively changed when ligands of site II are added, suggesting that it strongly interacts with the benzodiazepine/indole binding site on human serum albumin.

Binding Sites↗
PubMed1994

HIV-associated nephropathy--an initial presentation in an HIV-positive patient.

The lesions of HIV-associated nephropathy occur in patients with AIDS, AIDS-related complex and in individuals clinically asymptomatic for HIV infection. We report on a 35-year-old black South African woman who presented with nephrotic syndrome and renal failure. The renal biopsy appearance suggested HIV infection and this was subsequently verified. This finding emphasises the possibility that otherwise asymptomatic patients presenting with renal disease may be HIV-positive.

Adult↗
PubMed1993

Direct high-performance liquid chromatographic resolution of the enantiomers of tiaprofenic acid using immobilized human serum albumin.

Resolution of racemic tiaprofenic acid (TA) has been performed using immobilized human serum albumin as the stationary phase. The eluent was phosphate buffer-acetonitrile-n-octanoic acid (90:10:0.015, v/v). Detection was achieved at 305 nm. The pharmacokinetics of the enantiomers were studied following oral administration into humans and after subcutaneous injection in rats. Plasma concentrations of (+)-TA were much greater than those of (-)-TA. For the rat, the pharmacokinetic parameters between (-)-TA and (+)-TA were all statistically different (p < 0.005).

Administration, Oral↗
PubMed1993

Hyaluronidase degradation of hyaluronic acid from different sources: influence of the hydrolysis conditions on the production and the relative proportions of tetra- and hexasaccharide produced.

1. Hyaluronic acid (HA) can be digested with a Streptomyces hyaluronidase. 2. The rate of production and the ratio of tetrasaccharide (T) and hexasaccharide (H), studied by HPLC, varied with the temperature and duration of hydrolysis. 3. The rates of production and the respective amounts of the two oligosaccharides depended on the rheological properties of the HA from different sources. 4. A close relationship was found between the initial rate of hydrolysis and the intrinsic viscosity of the HA (eta i). 5. Our data suggest that enzymatic degradation at a given pH value, temperature, and duration of hydrolysis is dependent on the conformation of HA. 6. Moreover, under given conditions, the relative proportions of the two oligosaccharides depend on the eta i and may also reflect the degree of hydrolysis of the substrate.

Chromatography, High Pressure Liquid↗
PubMed1993

Pro- and anti-inflammatory properties of human recombinant IL-1 beta during experimental arthritis in rats: 2. Period-dependent effect.

The systemic effects of human recombinant Interleukin-1 beta (HrIL-1 beta) on hindpaw edema were determined in arthritis induced by human native type II collagen (CII) with muramyl dipeptide (MDP) both injected on day 0. Daily treatment with HrIL-1 beta (0.2 microgram sc) pretreatment, from D-1 (the day before MDP and CII were injected) to D3 significantly delayed the secondary inflammation in the uninjected left hindpaw, whereas the same treatment from D6 to D10 at the end of the "primary" inflammation, enhanced the volume of the left hindpaw. Treatment from D13 to D17 did not affect the "secondary" edema in the left hindpaw. Thus, HrIL 1 beta administration produces pro- or anti-inflammatory effects on a developing polyarthritis depending on when treatment is started and is most effective as an anti-inflammatory molecule when started at the peak of the the inflammatory reaction, as previously described. In view of these early findings, we have compared the effect of adding HrIL-1 beta along with MDP in the sensitization procedure on the time-course of CII-induced arthritis. No adjuvant effect of HrIL-1 beta was observed. On the contrary, HrIL-1 beta significantly decreased the signs of inflammation in the injected hindpaw during the secondary inflammation. In addition, the immune response to type II collagen was less in the group receiving HrIL-1 beta, maybe because of nonspecific increase of antigen clearance. On the other hand, the MDP sensitization procedure enhanced the incidence of CII arthritis and significantly worsened the clinical parameters in both primary and secondary inflammations.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1993

Protein binding and stereoselectivity of nonsteroidal anti-inflammatory drugs.

Stereoselective binding of nonsteroidal anti-inflammatory drugs (NSAIDs) can be studied using various techniques. Thus the results obtained by different investigators may be poorly consistent and even contradictory. NSAIDs are bound stereoselectively to serum albumin to different degrees depending on the drug investigated (ibuprofen, indoprofen, carprofen, etodolac, ketoprofen and flurbiprofen). For other drugs, both enantiomers are bound to a similar extent (pirprofen, fenoprofen). This stereoselectivity could vary with experimental conditions, in particular with protein concentration (ketoprofen, etodolac), leading to individual differences. Finally, the stereoselectivity of protein binding and of pharmacokinetics can be compared: differences in binding between enantiomers can explain their differences in pharmacokinetics, once metabolic properties such as inversion have been taken into account.

Animals↗
PubMed1992

Relation between the convergence temperatures Th* and Ts* in protein unfolding.

A challenge in understanding the thermodynamics of protein unfolding is to explain the 1979 puzzle posed by Privalov. Why do values of the specific enthalpy and specific entropy of unfolding both converge to common values at approximately the same temperature (Th* approximately equal to Ts*) when extrapolated linearly versus temperature? In 1986, a liquid hydrocarbon model gave an explanation for convergence of the specific entropies at Ts*: it happens because the contribution of the hydrophobic effect to the entropy of unfolding goes to zero at Ts*. The reason for convergence of the specific enthalpies at Th* and for the equality Th* approximately equal to Ts* has remained, however, a matter for speculation; recently, some explanations have been given that are based on models for polar interactions in protein folding. We show here that the relation Th* approximately equal to Ts* can be derived straightforwardly without making any assumptions either about polar interactions or about splitting the hydrophobic interaction into two terms--one for the "hydrophobic hydration" and the other for the residual effect, as suggested recently. Thus, the liquid hydrocarbon model explains both halves of Privalov's puzzle. A similar conclusion has been reached independently by A. Doig and D. H. Williams (personal communication). It has been proposed recently that a correction should be made for the relative sizes of a hydrocarbon solute and water when computing the thermodynamic properties of the hydrophobic interaction from a solvent transfer experiment. This correction affects the temperature at which the entropy of transfer equals zero, and it is important to evaluate its effect on the convergence temperature Ts*. We show that making the size correction does not change the conclusion, reached earlier, that the liquid hydrocarbon model explains the convergence of the specific entropies of protein unfolding.

Mathematics↗
PubMed1992

Stereoselective binding of etodolac to human serum albumin.

The protein binding of etodolac enantiomers was studied in vitro by equilibrium dialysis in human serum albumin (HSA) of various concentrations varying from 1 to 40 g/liter, by addition of each enantiomer at increasing concentrations. In the 1 g/liter solution, at the lowest drug levels, the (R)-form is more bound than its antipode, the contrary being observed at the highest drug levels. For higher albumin concentrations, S was bound in a larger extent than R. Using the displacement of specific markers of HSA sites I and II, studied by spectrofluorimetry, it was suggested that R and S are both bound to site I, while only S is strongly bound to site II.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1992

Does hydrophobic hydration destabilize protein native structures?

Water in the immediate vicinity of a non-polar solute has characteristically low entropy and high heat capacity at 25 degrees C. Common opinion has been that the insolubility of such species is caused by thermodynamic changes associated with the formation of these layers of abnormal water, 'hydrophobic hydration'. Recently, however, it has been proposed instead that hydrophobic hydration favors solution of hydrocarbons, or hydrocarbon sidechains, in water and therefore promotes protein unfolding. It is argued here that available data do not convincingly support this hypothesis.

Hydrogen Bonding↗
PubMed1991

Protein binding of indomethacin in human cerebrospinal fluid.

The binding of the non-steroidal anti-inflammatory drug indomethacin to proteins in human cerebrospinal fluid (CSF), drawn during lumbar puncture from 10 patients affected by lumbosciatica, was measured by equilibrium dialysis and spectrofluorimetry. Similar binding studies on human serum albumin solutions (0.5 and 1 g/L) were performed using the same techniques. The mean binding percentage of indomethacin determined by equilibrium dialysis was 40%. The results obtained by both techniques allowed us to conclude that the binding of indomethacin in CSF was essentially due to albumin.

Dialysis↗
PubMed1991

Assay of synovial fluid hyaluronic acid using high-performance liquid chromatography of hyaluronidase digests.

A high-performance liquid chromatographic method for the determination of hyaluronic acid levels in synovial fluids has been developed. The hyaluronidase sample digests, containing an internal standard (benzoic acid), were separated on a reversed-phase octadecylsilyl column eluted with 0.01 M tetrabutylammonium phosphate-acetonitrile (83:17, v/v) at pH 7.35. The determination was made on 1:10 diluted samples, by using a calibration curve from 50 to 500 micrograms/ml of human umbilical cord hyaluronic acid. For validation, the synovial fluids were simultaneously analysed by this method and a radiometric method: a high correlation was found between the two (correlation coefficient 0.94). The proposed method can be used to determine specifically the high hyaluronic acid levels of synovial fluids without interferences from other glycosaminoglycans or non-steroidal anti-inflammatory drug treatment.

Adolescent↗
PubMed1991

Protection against naturally acquired Rhodococcus equi pneumonia in foals by administration of hyperimmune plasma.

A 2-year field study was performed to determine the capability of increasing Rhodococcus equi specific antibody in foals via plasma transfusion or mare vaccination, to determine the kinetics of R. equi (ELISA) antibody decay and to assess the protective effects of these procedures in foals on a farm endemic for R. equi. Plasma donors were vaccinated with a killed R. equi bacterin and produced high levels of anti-R. equi antibodies, which were harvested by plasmapheresis. In Experiment 1, 68 foals were given 1 litre of hyperimmune plasma intravenously (i.v.) between 1-60 days of age. Foal plasma R. equi antibody was significantly increased and high levels of R. equi antibody (ELISA) were maintained for 60 days. No R. equi pneumonia developed in any foals receiving plasma. In Experiment 2, 99 pregnant mares were vaccinated with R. equi bacterin at 30, 60 and 90 days before foaling. Group 1 foals (101:85 from R. equi immunized mares) also received plasma transfusions and Group 2 foals (14), from R. equi immunized mares, did not receive plasma transfusions. Pregnant mare immunization increased colostrum R. equi antibody significantly. Eight foals showed failure of transfer of specific R. equi antibody. The incidence of R. equi pneumonia was 2.9% in Group 1 foals and 43% in Group 2 foals. Vaccination of pregnant mares did not provide protection against R. equi pneumonia; however, plasma transfusion with hyperimmune plasma administered prior to R. equi exposure was significantly protective in foals.

Actinomycetales Infections↗
PubMed1990

Pharmacological aspects of chiral nonsteroidal anti-inflammatory drugs.

Most NSAIDs are chiral molecules: they exist under 2 configurations of non-superimposable mirror images which are termed enantiomers or optical isomers or optical antipodes. Direct or indirect (resolution) methods are used to separate this equal mixture of compounds. Some of the enantiomers of the NSAIDs are able to undergo chiral inversion from the inactive R(-) to the active S(+) form. The pharmacokinetics in terms of absorption, distribution, metabolism, protein binding and elimination may be different for the 2 enantiomers, leading to interindividual variability in clinical response and drug toxicity.

Animals↗