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PubMed1988

Conversion of 5-hydroperoxyeicosatetraenoic acid into leukotriene B4 by rat hepatocytes: a novel cellular source for leukotriene B4.

Rat hepatocyte homogenates converted 5-hydroperoxyeicosatetraenoic acid into leukotriene B4 (LTB4). The reaction was dependent on time and protein and substrate concentration, did not require NADPH or oxygen, and was not supported by heat-inactivated hepatocyte homogenates. The authenticity of the biologically generated LTB4 that eluted at the position of synthetic LTB4 during high performance liquid chromatography was established by UV spectrophotometry, mass spectral analysis, radioimmunoassay, and a LTB4 receptor displacement assay. In addition, a leukotriene bioassay is described in which transient increases in cytosolic Ca2+ within human neutrophils are measured by means of fura-2 fluorescence. Biologically generated LTB4 was 40, 40, and 33% as active as synthetic LTB4 in the radioimmunoassay, receptor displacement assay, and cytosolic calcium bioassay, respectively. This activity is consistent with the biologically derived LTB4 being an epimeric mixture of (5S),(12R)-LTB4 and the much less active (5S),(12S)-LTB4. The formation of LTB4 was inhibited by 5,8,11,14-eicosatetraynoic acid (1 mM), 5,6-dehydro-arachidonic acid (50 microM), propanethiol (1 mM), and O2 (100%) to the extent of 53, 42, 48, and 66%, respectively. No inhibition was observed in the presence of diethylcarbamazine (1 mM) and desferal (1 mM). A possible contribution towards LTB4 formation by contaminating Kupffer cells was excluded (less than 0.2%). These results suggest that hepatocytes can convert lipid peroxides into potent chemoattractants that may alter the homeostasis of immunomediators within the liver.

Animals↗

PubMed1999

Retrospective analysis of the frequency and recognition of adverse drug reactions by means of automatically recorded laboratory signals.

AIMS: To estimate the frequency of adverse drug reactions (ADRs) identified through the use of automatic signals generated from laboratory data (ALS) in hospitalised patients. To determine the frequency of spontaneous recognition of these ADRs by the attending physicians and to assess the potential value of ALS for detection of ADRs. METHODS: Laboratory results of patients hospitalised in a nine bed medical ward were automatically recorded over a period of 17 months. Values exceeding defined boundaries were used as ALS. Charts of every third patient were analysed retrospectively with regard to adverse drug related reactions and causality was evaluated as well as whether the ADR had been recognised during the period of hospitalisation. RESULTS: The charts and ALS of 98 patients were analysed. In 18 cases a drug-related adverse reaction was probable. Awareness to the reaction by the treating physicians was evident in 6 out of these 18 ADRs. Approximately 80% of the ADRs were considered predictable. Three ADRs were regarded as serious. CONCLUSIONS: Adverse drug reactions are common and often preventable. Only one third of ADRs which could have been detected through ALS were recognised by the attending physicians. An increased doctor's awareness of the frequency of drug related abnormal laboratory results by means of ALS is likely to increase the recognition rate of ADRs and might help to prevent them.

Adult↗

PubMed1988

Type 2 (non-insulin-dependent) diabetes mellitus. New genetics for old nightmares.

In the last five years, genetic markers for a large number of diseases have been localised using linkage analysis of DNA polymorphisms in affected families. The site of the genetic defect or defects leading to Type 2 (non-insulin-dependent) diabetes mellitus, a common illness with a major genetic component, remains unknown. This is due, at least in part, to the lack of large well-defined Type 2 diabetic pedigrees suitable for linkage analysis. There are several features of the disease which make large pedigrees difficult to find. The late age of onset of most probands means that informative older generations are often dead, while there is difficulty in detecting disease in younger generations. The diagnostic criteria for diabetes are, as yet, dependent on an arbitrary cut-off along a continuum of plasma glucose. The high prevalence of the disease may also produce problems as, in any given family, diabetogenic genes may be contributed by more than one parent. Varieties of the disease with a well-defined inheritance, such as maturity onset diabetes of youth, are more suitable for linkage analysis but might be due to defects at a different gene locus. Despite these difficulties, once large well-defined pedigrees have been found, linkage analysis using both candidate genes and random highly polymorphic markers is the strategy most likely to find genetic markers for the disease.

Diabetes Mellitus, Type 2↗

PubMed1995

Categorization of heart rate-eye movement patterns in human fetuses using the statistical technique of discriminant analysis.

The purpose of this study was to determine if discriminant analysis could be used to categorize fetal heart rate (FHR) - fetal eye movement (FEM) patterns. Statistical characteristics from 27 normal human fetuses at term for behavioral states, transitions, and insertions were established by combining the digitized FHR-FEM data for subjectively identical epochs. The mean FHR, the variance about the mean, and the presence or absence of FEM were calculated for each 3-min block in a sliding moving window with a 1-min step size. For each fetus, discriminant analysis was then used to assign 3-min blocks to either a behavioral state, a transition, or an insertion by comparing the statistical properties of a 3-min block with that of the data base. We found no difference between discriminant analysis and visual assignment in the average time spent in behavioral states 1F, 2F, and 4F, or in the mean duration of the transition/insertion periods. There was a highly significant linear relationship between computer-generated and visually-determined durations for behavioral states 1F (r = 0.972, p < 0.0001) and 2F (r = 0.989, p < 0.0001) and for the transition/insertion periods (r = 0.863, p < 0.0001). We conclude that discriminant analysis is a reliable computer-based method for behavioral state identification.

Discriminant Analysis↗

PubMed2005

Genome-wide linkage analysis to age at natural menopause in a community-based sample: the Framingham Heart Study.

OBJECTIVE: To identify chromosomal regions linked to age at natural menopause. DESIGN: Two-generation families studied with a 10-centimorgan (cM) genome-wide scan. SETTING: The Framingham Study, a community-based epidemiologic study. PATIENT(S): A total of 861 women in 291 families reporting a natural menopause (mean age at menopause, 49 years). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Multipoint variance components linkage analysis was performed with Genehunter software (Whitehead Institute, Massachusetts Institute of Technology, Boston, MA) for age at natural menopause. RESULT(S): In the crude variance components analysis, 11 chromosomes had a log odds ratio (LOD) score of > or =1.0. Two chromosomal regions revealed suggestive linkage: chromosome 8 at 26 cM (LOD 2.6; nearest marker GATA23D06) and chromosome 16 at 11 cM (LOD 2.4; nearest marker ATA41E04). In the analysis adjusted for generation, smoking, and body mass index, chromosome 11 revealed suggestive linkage at 113 cM (LOD 2.1; nearest marker GATA23E06). CONCLUSION(S): We have identified novel loci suggestive for linkage to age at natural menopause. Further research is needed to identify genes involved in the onset of menopause, which might provide insights into loss of fertility.

Adult↗

PubMed2004

Population pharmacokinetic analysis of mirtazapine.

OBJECTIVE: Mirtazapine belongs to the new generation of antidepressants that is commonly used in clinical routine. Therefore, we feel it mandatory to control compliance in the context of non-response, adverse events or other clinical situations by means of plasma concentration measurements. While controlled clinical studies have evaluated the effect of individual covariates on the pharmacokinetics of mirtazapine, our analysis aims to identify covariates within a naturalistic clinical setting. METHODS: We performed non-linear mixed-effects modelling with data from 65 depressed inpatients whose plasma concentrations were measured weekly during their stay in hospital. Each patient's age, height, weight, co-medication, alcohol, coffee and cigarette consumption, weekly serum creatinine concentrations, liver enzyme activity, blood pressure and pulse was noted. From 49 patients, the genotype of cytochrome P450 (CYP) isoenzymes 2D6, 2C9 and 2C19 was analysed. RESULTS: The clearance of CYP2D6 intermediate metabolisers was reduced by 26% compared with extensive metabolisers. No other factor significantly influenced the clearance of these patients. CONCLUSION: The variability of mirtazapine plasma concentrations in clinical routine is caused to a relevant degree by CYP2D6. This should be taken into account when therapeutic drug monitoring is carried out to check treatment adherence or when a special clinical situation, such as co-morbidity and add-on medication, demands careful dosing of this drug.

Antidepressive Agents, Tricyclic↗

PubMed2005

Colonization of Ochlerotatus taeniorhynchus from Riohacha, Colombia.

The main objective of the present work was to establish and maintain a colony of Ochlerotatus taeniorhynchus, Riohacha strain, under laboratory conditions and to study its life cycle. The colony's insectary was established from adult male and female mosquitoes collected from peripheral neighborhoods of Riohacha, Colombia. Environmental conditions established in the insectary were 26.5 degrees C average temperature, 80% average relative humidity, and 12 h photoperiodicity. Eight continuous generations were taken into account for maintaining the mosquitoes and analyzing their life cycle. The male mosquito's average life cycle was 26.8 days. The female's cycle was 30.8 days. Analysis of each of the biological stages of development (mean days) produced the following results: egg incubation 4.55 +/- 0.291, larvae 8.28 +/- 0.499, pupae 1.32 +/- 0.215, adult male 12.65 +/- 5.920. and adult female 16.73 +/- 6.034. The Riohacha colony has been maintained for 32 generations in 31 months. Comparison of the Riohacha colony with the previously established Cartagena and Barranquilla colonies showed few differences in the duration of stages of the life cycle between strains.

Animals↗

PubMed1991

Distance-constraint approach to higher-order structures of globular proteins with empirically determined distances between amino acid residues.

An analysis of higher-order structures of globular proteins by means of a distance-constraint approach is presented. Conformations are generated for each of 21 test proteins of small and medium sizes by optimizing an objective function f = sigma sigma wij(dij - (dij]2, where dij is a distance between residues i and j in a calculated conformation, (dij) is an assigned distance to the (ij) pair of residues which is determined based on the statistics of known three-dimensional structures of 14 proteins in the earlier study, and wij is a weighting factor. (dij) involves information about hydrophobicity and hydrophilicity of each amino acid residue and about connectivity of a polypeptide chain. In these calculations, only the amino acid sequence is used as input data specific to a calculated protein. With respect to higher-order structures regenerated in the optimized conformations, the following properties are analyzed: (a) N14 of a residue, defined as the number of residues surrounding the residue located within a sphere of radius of 14 A; (b) root-mean-square differences of the global and local conformations from the corresponding X-ray conformations; (c) distance profiles in the short and medium ranges; and (d) distance maps. The effects of supplementary information about locations of secondary structures and disulfide bonds are also examined to discuss the potential ability of this methodology to predict the three-dimensional structures of globular proteins.

Amino Acids↗

PubMed1984

Non-random chemoreceptor activity during superfusion in vitro.

As a means of probing the chemotransducer, impulse sequences from in vitro, superfused sinus nerve-carotid body preparations were analyzed for departures from randomness. Twelve of 17 spike trains showed interval histograms that did not differ significantly from exponential. Thus these sequences resembled a Poisson (random) process with respect to time-independence of probability of occurrence of an event. However, 5 spike trains departed significantly from the exponential distribution forcing rejection of the Poisson model in these cases. Furthermore, mean interval vs standard deviation analysis revealed a significant positive correlation among intervals. These data suggest that the carotid body impulse generator possesses an intrinsic regularity and that the Poisson model does not accurately describe the in vitro sinus nerve interspike interval sequence.

Action Potentials↗

PubMed1992

Spontaneous beat-to-beat variability of the ventricular repolarization duration.

The spontaneous beat-to-beat variability of the ventricular repolarization duration was investigated in 21 healthy subjects (age 25-71 years; mean, 40 years) during the basal state in a recumbent position. For each subject, approximately 1,000 consecutive cycles were analyzed with an automated technique. The time series of the RR, QT, and RT intervals generate histograms that approximate normal distributions and have mean standard deviations of 57.0 ms, 5.4 ms, and 4.3 ms, respectively. Spectral analysis was used to detect rhythmical oscillations in these time series. The power spectra densities of both heart rate and ventricular repolarization during show peaks in the same frequency bands: low frequency (0.05-0.12 Hz) and high frequency (0.2-0.4 Hz). The power distribution between these two bands observed in the ventricular repolarization duration spectra was found to be the reverse of that in heart rate spectra (p less than 0.005).

Adult↗

PubMed2004

Evolution of an in vivo bioreactor.

The ideal bone graft substitute requires osteoconductive, osteoinductive, and osteogenic components. This study introduces an "in vivo bioreactor," a model in which pluripotent cells are recruited from circulating blood to a vascularized coralline scaffold supplemented with bone morphogenetic protein-2 (BMP-2). The bioreactor generates new, ectopic host bone with the capability of vascularized tissue transfer. More importantly, bone is reproducibly formed in a closed and malleable environment. In a rat model, the superficial inferior epigastric vessels were isolated, ligated, and then threaded through a prefabricated coral cylinder (hydroxyapatite, ProOsteon 500). Experimental groups were characterized by the following variables: (1) with/without incorporation of vascular pedicle; (2) with/without addition of BMP-2 (0.02 mg/cm3). Scaffolds were harvested 6 weeks after implantation, embedded and sectioned. Tissue samples were decalcified, fixed, and stained with H&E, trichrome green, and CD31/PECAM-1 (a marker of endothelial cells). Vascularized coral scaffolds supplemented with BMP-2 presumably recruited circulating mesenchymal stem cells to generate bone. Bone formation was quantified through histological analysis, and reported as a percentage, area bone/area cross section scaffold x 100. Mean bone formation was 11.30%+/-1.19. All scaffolds supplied by the vascular pedicle, regardless of BMP-2 supplementation, demonstrated neo-vascular ingrowth. Scaffolds lacking a pedicle showed no evidence of vascular ingrowth or bone formation. This paper introduces a model of a novel "in vivo bioreactor" that has future clinical and research applications. The tissue engineering applications of the "bioreactor" include treatment of skeletal defects (nonunion, tumor post-resection reconstruction). The bioreactor also may serve as a unique model in which to study primary and metastatic cancers of bone.

Animals↗

PubMed1993

A pre-transition-state mimic of an enzyme: X-ray structure of adenosine deaminase with bound 1-deazaadenosine and zinc-activated water.

The refined 2.4-A structure of adenosine deaminase, recently discovered to be a zinc metalloenzyme [Wilson, D. K., Rudolph, F. B., & Quiocho, F. A. (1991) Science 252, 1278-1284], complexed with the ground-state analog 1-deazaadenosine shows the mode of binding of the analog and, unexpectedly, a zinc-activated water (hydroxide). This structure of a pre-transition-state mimic, combined with that previously determined for the complex with 6(R)-hydroxy-1,6-dihydropurine ribonucleoside, a nearly ideal transition-state analog, sheds new understanding of the precise stereospecificity and hydrolytic catalysis of an important and well-characterized member of a large group of zinc metalloenzymes. As both of these excellent mimics were generated in the active site, they demonstrate a powerful means of dissecting the course of an enzymatic reaction by direct crystallographic analysis.

Adenosine Deaminase↗

PubMed1997

The 30/35 kDa chymotryptic fragment of fibronectin enhances retroviral-mediated gene transfer in purified chronic myelogenous leukemia bone marrow progenitors.

We have previously shown by reverse transcriptase-PCR (rtPCR) that CML CD34+ HLA-DR- cells are enriched for BCR/ABL(-) hematopoietic progenitor cells (HPC) while leukemic HPC reside predominately within CML CD34+ HLA-DR+ cells. We investigated whether the 30/35 kDa fragment of fibronectin (FN) could be used to enhance retroviral-mediated gene transfer (RMGT) in chronic phase CML marrow HPC. CML CD34+ HLA-DR- and CD34+ HLA-DR+ cells were transduced with vector supernate containing the neomycin resistance gene on plates coated with either FN or bovine serum albumin (BSA) as control, then assayed for transduced HPC in progenitor cell assays in the presence or absence of G418. Transduction efficiency of CML CD34+ HLA-DR- cells over BSA ranged from 0.09 to 7.2% (mean 3.3 +/- 1.5%), while that over FN plates ranged from 3.8 to 23% (mean 11.0 +/- 4.5%) (n = 4). Transduction efficiencies of CML CD34+ HLA-DR+ cells ranged from 0.4 to 9.8% (mean 3.7 +/- 1.7%) and 6.0 to 26% (mean 17.3 +/- 4.5%) (n = 5) over BSA and FN, respectively. rtPCR analysis for BCR/ABL mRNA of individual G418-resistant HPC generated from CD34+ HLA-DR- cells revealed that normal BCR/ABL(-) HPC were successfully transduced under these experimental conditions. These results demonstrate the feasibility of transducing normal CML primitive HPC, and illustrate the potential clinical use of FN in the setting of gene therapy for CML, as well as other diseases.

Adult↗

PubMedDate not supplied

Age-related changes in apparent digestibility in growing kittens.

The ability of the growing kitten to digest protein, fat, carbohydrate, dry-matter and energy were assessed. Kittens were divided into two groups; one group was fed a wet diet, the other a dry diet. Both groups were allowed ad libitum access to food. Apparent digestibility of the two diets, and kitten bodyweights were measured over a 24-week period. There were no significant differences in mean bodyweight between the two groups. Digestible energy intake of the kittens decreased with increased age; regression analysis of the data generated two fitted models which appeared to accurately predict the digestible energy intake between 39 and 41 weeks of age. There was a significant (P < 0.05) effect of diet on the apparent digestibility of protein, organic-matter and dry-matter. Age had a significant (P < 0.05) effect on the apparent digestibility of all the parameters measured. Newman-Keuls multiple range tests showed that apparent digestibility of carbohydrate, organic-matter and total energy significantly (P < 0.05) increased in kittens older than 19 weeks. This suggests that the digestive capacity of the younger cat may be affected by the physiological development of the gut, and dietary induced enzyme modulation.

Aging↗

PubMed2001

Forecasting generation of urban solid waste in developing countries--a case study in Mexico.

Based on a study of the composition of urban solid waste (USW) and of socioeconomic variables in Morelia, Mexico, generation rates were estimated. In addition, the generation of residential solid waste (RSW) and nonresidential solid waste (NRSW) was forecasted by means of a multiple linear regression (MLR) analysis. For residential sources, the independent variables analyzed were monthly wages, persons per dwelling, age, and educational level of the heads of the household. For nonresidential sources, variables analyzed were number of employees, area of facilities, number of working days, and working hours per day. The forecasted values for residential waste were similar to those observed. This approach may be applied to areas in which available data are scarce, and in which there is an urgent need for the planning of adequate management of USW.

Developing Countries↗

PubMed1979

Clinical problem solving and clinical knowledge.

Videotape and simulated patients were used for evaluating third year medical students' performances in solving familiar and unfamiliar clinical problems. To assist the doctor to rate the students' performances by the review of videotapes, criteria were set up for students' behaviours that could be construed as evidence that the students recognized cues obtained by interviewing the patient and the information content of such cues. Criteria for data use by the students were also set. A mean of 90% of the pertinent medical history data was collected by the students. The amount of pertinent historical data collected was found to correlate very closely with student-patient interaction analysis score for the familiar and unfamiliar problems (r = 0.89 and r = 0.92, respectively). Significant differences in mean scores for data generation (P less than 0.001) and for data use (P less than 0.01) were found between those students who solved and those who failed to solve the familiar problem. With the unfamiliar problem a significant difference was found between the mean scores for data generation (P less than 0.01), but not for data use. The implications of these findings in medical education are discussed.

Clinical Competence↗

PubMed2006

alpha-tubulin minichromosome promoters in the stichotrichous ciliate Stylonychia lemnae.

Ciliated protists are model organisms for a number of molecular phenomena including telomerase function, self-splicing introns, and an RNA interference-related mechanism in programmed DNA elimination. Despite this relevance, our knowledge about promoters and transcriptional regulation in these organisms is very limited. The macronuclear genome of stichotrichous ciliates consists of minichromosomes which typically encode a single gene. The 5' nontranscribed spacers are usually no longer than 400 bp and highly suitable for promoter characterizations. We used microinjection of two artificial and differently tagged alpha1 tubulin minichromosomes into the macronucleus of Stylonychia lemnae as a means to characterize in detail the corresponding promoter. Clonal cell lines that stably maintained both minichromosomes were generated, enabling comparative expression analysis by primer extension assays. Deletion and block substitution mutations of one of the minichromosomes revealed a TATA-like element, a putative initiator element, and two distinct upstream sequence elements (USEs). Determination of transcription initiation sites and a sequence alignment indicated that both TATA-like and initiator elements are conserved components of S. lemnae minichromosomes, whereas the USEs appear to be specific for the alpha1 tubulin minichromosome. The alpha2 tubulin minichromosome promoter is very short, comprising the two proximal elements but not the USEs. Despite the latter finding, up-regulation of alpha-tubulin expression in cells treated with concanavalin A activated the alpha2 but not the alpha1 tubulin promoter. These results therefore show that gene expression regulation in S. lemnae occurs at the level of transcription initiation on the basis of structurally different promoters.

Amino Acid Substitution↗

PubMed2002

Function of the heterocercal tail in sharks: quantitative wake dynamics during steady horizontal swimming and vertical maneuvering.

The function of the heterocercal tail in sharks has long been debated in the literature. Previous kinematic data have supported the classical theory which proposes that the beating of the heterocercal caudal fin during steady horizontal locomotion pushes posteroventrally on the water, generating a reactive force directed anterodorsally and causing rotation around the center of mass. An alternative model suggests that the heterocercal shark tail functions to direct reaction forces through the center of mass. In this paper, we quantify the function of the tail in two species of shark and compare shark tail function with previous hydrodynamic data on the heterocercal tail of sturgeon Acipenser transmontanus. To address the two models of shark heterocercal tail function, we applied the technique of digital particle image velocimetry (DPIV) to quantify the wake of two species of shark swimming in a flow tank. Both steady horizontal locomotion and vertical maneuvering were analyzed. We used DPIV with both horizontal and vertical light sheet orientations to quantify patterns of wake velocity and vorticity behind the heterocercal tail of leopard sharks (Triakis semifasciata) and bamboo sharks (Chiloscyllium punctatum) swimming at 1.0Ls(-1), where L is total body length. Two synchronized high-speed video cameras allowed simultaneous measurement of shark body position and wake structure. We measured the orientation of tail vortices shed into the wake and the orientation of the central jet through the core of these vortices relative to body orientation. Analysis of flow geometry indicates that the tail of both leopard and bamboo shark generates strongly tilted vortex rings with a mean jet angle of approximately 30 degrees below horizontal during steady horizontal swimming. The corresponding angle of the reaction force is much greater than body angle (mean 11 degrees ) and the angle of the path of motion of the center of mass (mean approximately 0 degrees ), thus strongly supporting the classical model of heterocercal tail function for steady horizontal locomotion. Vortex jet angle varies significantly with body angle changes during vertical maneuvering, but sharks show no evidence of active reorientation of jet angle relative to body angle, as was seen in a previous study on the function of sturgeon tail. Vortex jet orientation is significantly more inclined than the relatively horizontal jet generated by sturgeon tail vortex rings, demonstrating substantial differences in function in the heterocercal tails of sharks and sturgeon. We present a summary of forces on a swimming shark integrating data obtained here on the tail with previous data on pectoral fin and body function. Body orientation plays a critical role in the overall force balance and compensates for torques generated by the tail. The pectoral fins do not generate lift during steady horizontal locomotion, but play an important hydrodynamic role during vertical maneuvering.

Animals↗