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At least 1,531 records · Page 85Linked to original sources

PubMed2000

Predicting amphipods' brood size variation in brackish environments: an empirical model for Corophium multisetosum Stock, 1952 (Corophiidae) in Ria de Aveiro (NW Portugal).

Data on fecundity of Corophium multisetosum from Areão (Ria de Aveiro, Portugal) are analysed by non linear regression to quantify the relationship between brood size (N(e)) and head length (L(h), in mm), water temperature (T, in degrees Celsius) and salinity (S, in psu). The aim of the analysis is to obtain a simple line N(e)=a+bL(h), in which the slope (b) and the y intercept (a) are functions of salinity and/or temperature on each sampling occasion. The equation N(e)=(-2.940-8.027S)+(-89.431+18.171S+12.904T-0.368T(2))L(h) explains 64% of the variability of brood size throughout the breeding period. The model predicts an optimal temperature around 18 degrees C and a very low fecundity at low salinities. The graphical comparison of the lines obtained by the model and by a usual linear regression illustrates its potential usefulness to predict fecundity changes. The authors suggest that the observed variation in the fecundity of other brackish-water amphipods can be described and predicted using similar models.

Journal Article↗

PubMed1998

Lifestyle factors fail to explain the variation in plasma leptin concentrations in women.

To assess the relationship between circulating leptin concentrations, metabolic parameters, and lifestyle factors such as alcohol intake, physical activity level, smoking habits, and reproductive history, a cohort of 359 women was drawn from a population-based study conducted in Victoria, Australia. The parameters measured included body mass index (BMI); waist and hip circumference; blood pressure; and fasting glucose, insulin, triacylglycerol, cholesterol, and leptin concentrations. In addition, a self-administered questionnaire was used to assess reproductive history, physical activity level, alcohol intake, and smoking habits. Our results demonstrated that BMI, body weight, waist circumference, and hip circumference were all strongly correlated with circulating leptin concentrations in this population (r > 0.56, P < 0.001 in all cases). Waist/hip ratio, triacylglycerols, insulin, glucose, and cholesterol were also associated with leptin (P < 0.05), but there was no association between leptin and age, height, or blood pressure. When these associations were adjusted for BMI, age, glucose, and waist circumference were significantly associated with leptin. The lifestyle factors examined did not help to explain the observed variation in leptin concentrations between individuals when results were adjusted for degree of adiposity and age.

Adult↗

PubMed1985

Conference on insulin pump therapy in diabetes. Multicenter study of effect on microvascular disease. Assessment of fluorescein angiograms.

Quantitation of the earliest changes in abnormal retinal morphology using fluorescein angiography is potentially superior to retinal photography. However, the critical importance of flawless technique, limitations in the size of the field available for detailed study, and observer variability constitute major disadvantages. A protocol describing standards of photography and of injection was developed. Methodology for counting microaneurysms (Ma) was developed at a central laboratory and applied in suitable photographs obtained at 0 (baseline), 4, and 8 mo in 68 patients. Counts of "definite" or "possible" Ma were made on films projected under standard conditions by two observers known to achieve consistently reproducible results. Semiquantitative assessment of diffusibility of fluorescein reflecting capillary leakage was performed in 61 patients. Leakage was graded according to three degrees of severity permitting study of observer variation, concordance of change in pairs of eyes, and treatment effects. The average number of Ma at baseline was slightly higher in the continuous subcutaneous insulin infusion (CSII) group than in the conventional insulin treatment (CIT) group, but the difference was not statistically significant at the 0.05 level. At both 4 and 8 mo, definite Ma were more prevalent in the CSII group, and the difference was statistically significant at the 0.05 level using both parametric and nonparametric tests. In 27 CSII and 23 CIT patients having complete sets of 0, 4, and 8-mo photographs, Ma counts increased during the 0-4-mo interval. During the 4-8 mo interval, a further increase occurred in the CSII group but contrasted with a decrement observed in the CIT group, which showed no net change from baseline.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm↗

PubMedDate not supplied

Diagnostic efficiency of paramedical workers involved in leprosy case detection programme.

The diagnostic efficiency and accuracy in classification of leprosy and its activity status, by four senior trained Paramedical Workers (PMWs) involved in leprosy case detection programme, was assessed on 1394 cases detected by them and concurrently confirmed by an experienced medical officer. The inter-observer variation between two experienced PMWs in diagnosis and classification of leprosy on 216 patients, was also studied. Of the 1394 cases detected by PMWs, 257 (18.44%) were wrongly diagnosed as leprosy, mostly as non-lepromatous (N) type. Though all lepromatous (L) and 98% of N-type cases were correctly classified by PMWs, 25.64% of borderline (N ? L) cases were either under-diagnosed as N-type (17.95%) or over-diagnosed as L-type (7.69%). The activity status of 19% cases was wrongly assessed by PMWs, including 8% active lesions assessed as inactive. The discrepancy between two PMWs in diagnosis, classification and assessment of activity status of leprosy was found in 1.39%, 7.41% & 25.67% cases, respectively. The implications of these observations, and the suggestions to improve the technical skills of workers for an efficient and effective implementation of leprosy control programme, are discussed in this communication.

Allied Health Personnel↗

PubMed2001

Mass spectrometric studies on small open-chain piperazine-containing ligands and their transition metal complexes.

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was used to characterize the complexes formed between open-chain piperazine-containing ligands and transition metal salts (Cobalt, Copper, Zinc, and Cadmium as chlorides, nitrates, and acetates). Only single-charged complexes were observed, formed of one ligand (L) and mainly one metal ion (M). Since the net charge of the complexes was one, a counterion (X) was attached to some of the complexes, with formation of [L + M + X]+ complexes, and a proton was lost from others, as in [L - H + M]+ complexes. In most cases the composition of the complexes was more dependent on the ligand than the metal salt. Collision-induced dissociation measurements showed that complexes with related composition often differed in structure, or that interactions between the ligand and the metal ion were not alike. The metal ion influenced considerably the fragmentation pathways of the ligands, so that the fragmentation products could be used to deduce the binding sites of the metal. The variations observed in fragmentation behavior of complexes possessing the same ligand but different metal ions can mostly be explained by the ionic radius and electronic configuration of the metal ion. The results indicated a preference of the piperazine ring of the coordinated ligand for the boat conformation.

Cobalt↗

PubMed1999

Adaptation of the human calcaneus to variations of impact forces during running.

OBJECTIVE: The influence of varied forces under the heel induced by changes in midsole hardness on adaptations of the human calcaneus during running training was investigated. DESIGN: A longitudinal study was conducted over a period of 20 weeks with subjects training for 50 km per week on average. BACKGROUND: The skeletal systems' metabolism acts highly dynamic, governed by mechanical factors. The amount of running training has been shown to increase the bone mineral density in the calcaneus. Mechanical factors have not been controlled in former investigations. METHODS: Bone quality parameters were determined before and after the training by use of an ultrasound system and quantitative MRI while the mechanics of foot-ground contact were controlled. The total group of 26 subjects was divided into three subgroups based upon different magnitude of forces under the heel inside the shoe. RESULTS: The biomechanical testing demonstrate no relationship between midsole hardness and external or in-shoe impacts. Bone parameters showed specific differences for all groups which are pronounced in runners with intermediate impacts. CONCLUSIONS: The observed variations reflect metabolic changes in bone marrow which appear to be effected by the impact magnitude and cannot be characterised as negative. RELEVANCE: The current data imply that no negative changes of impacts on calcaneal bone were produced by high amounts of training in distance running. The mechanical testing indicates that the potential of modifying calcaneal adaptation directly by varying midsole hardness is limited.

Adaptation, Physiological↗

PubMed1996

Macroinvertebrate community as a biological indicator of ecological and toxicological factors in Lake Saint-François (Québec).

To assess the potential of the macroinvertebrate community for monitoring variation in the environmental quality of large rivers, the response of littoral macrobenthos in Lake Saint-François, a fluvial lake of the St Lawrence River (Québec) are described. First, the composition of total macroinvertebrate communities and important taxonomic groups as well as the biotic ICI-SL index in 16 littoral stations varying in sedimentology, water chemistry and contamination are described to define indicator species groups and environmental quality ranks. Thereafter, the relative contribution of ecological and toxicological factors in explaining the variation observed in macroinvertebrate assemblages and biotic index were quantified using partial canonical correspondence analysis. Cluster analyses based on taxonomic composition separated five groups of stations where macroinvertebrate assemblages varied in density, composition and tolerance to pollution. The ICI-SL biotic index varied from 7.2 to 27.2 with a mean value of 19 +/- 6. The ICI-SL values determined for the macroinvertebrate communities in Lake Saint-François did not reflect an important deterioration in environmental quality, and there was some agreement between the environmental quality ranking of the stations expressed either by the ICI-SL index or the community cluster analysis. Water conductivity and phosphorus concentration, followed by macrophyte types (Chara, Ceratophyllum) and sediment grain size, were the most significant ecological variables to explain variation in macroinvertebrate communities and derived ICI-SL index in Lake Saint-François. Among the toxicological factors, metals in water (Fe, Cr, Pb, Mn, Zn) and sediment (Mn, Pb, Se), as well as the composite indices of metal and organic contamination (water CI, sediment CI, sediment total PAHs) were the most important factors. The contamination factors selected in our models represented contaminant sorption processes rather than direct toxicological effects. The lack of clear relationships between contaminants and macroinvertebrate variables reflected the relative low level of contamination in the stations sampled in Lake Saint-François. There were some interactions between toxicological and ecological variables that should be considered in the planning of sampling and interpretation of biomonitoring studies. However, the large amount of unexplained variance (49.2-86.6%) in the CCA models underlined the limitations of the use of the indices of macroinvertebrate community structure that were assessed in this study for biomonitoring purposes in the absence of a contrasting pollution gradient.

Journal Article↗

PubMed2026

Long-read Sequences Mapped to a Complete Reference Genome Uncover Uncaptured Structural Variants across the Beta-globin Cluster in Africans with Sickle Cell Disease.

African genomes are marked by extensive complexity in the number and distribution of variants, yet remain under-represented in genetic databases and the human reference genome. This gap in representation limits the broad application of genomic medicine. Sickle cell disease (SCD) - one of the most common monogenic diseases - has its highest prevalence in Africa, and variation in disease severity has consistently been linked to the beta-globin locus, including levels of fetal hemoglobin (HbF). Modulation of HbF is central to current SCD gene therapies; however, the inherent complexity and variation at the locus in African genomes presents a challenge to translating these advances to Africa. Here, we align long-read single molecule sequences (LRS) targeted to the beta-globin region to the hg38 and T2T-CHM13v2 genome references in 40 individuals with SCD, predominantly recruited from three African countries. We demonstrate that the expanded T2T-CHM13v2 reference sequence at this locus reduces Structural Variant (SV) calls by 70% and uncovers uncaptured single nucleotide variants (SNVs). Across the cluster we report 343 SVs and 196 SNVs that have not been previously reported, including in LRS data from the All of Us project. By including African populations from ethnolinguistic groups that have not been previously surveyed we improve variant resolution and bolster evidence for observed variation. Finally, we identify a common ∼4kb insertion locus overlapping the HBB promoter among individuals with high HbF. These results demonstrate the utility of combining a comprehensive reference genome with LRS in African populations to uncover genomic variation at disease-associated loci.

SNV↗

PubMed1999

Conventional spiral and low-dose computed mandibular tomography for dental implant planning.

Absorbed doses to radiosensitive organs in the head and neck from pre-implant conventional hypocycloidal, conventional spiral and computed tomography (CT) were measured with thermoluminescent dosimeters in an anthropomorphic phantom head. From conventional tomography organ doses, except to the major salivary glands, were below 0.2 mGy. They were considerably higher with CT than conventional tomography. Tomographic images of posterior lower jaw regions were evaluated regarding measurement reliability in conventional spiral tomograms. Observers measured the distance marginal crest-mandibular canal, marked their measuring points and estimated the length of an intended Brånemark implant. The variability between observers, mainly due to the intra-observer variation, decreased with multiple readings and optimized image quality. The suggested implant length was the same as the one inserted in 70% of the cases. Tomographic images from mandibular body segments were used to test the influence of radiation exposure and scanning mode on image quality in CT and compare the quality of the CT images with that in conventional spiral tomograms. Mandibular canal and marginal bone crest visibility was unaffected by radiation dose in CT examinations. Differences among CT scanning modes and between CT and conventional spiral tomography were highly significant. Frontal CT scans or conventional spiral tomograms were preferred. In cross-sectional images of the posterior lower jaw image quality in conventional spiral and reformatted CT at 40 mAs and 80 mAs was compared. Observers graded the acceptability of images for implant planning and traced the contours of the mandibular body and canal. Conventional, spiral tomograms were subjectively preferred over reformatted CT images. Differences between CT images at different mAs settings were not statistically significant. The mandibular canal was more frequently untraceable in high-dose CT. The use of tomography for dental implant planning was studied by means of a survey among oral radiology clinics in Sweden and implantology clinics in other countries. It was used by 93.4% but varied markedly between and within anatomic regions. CT was used by 73%. Radiation doses varied considerably within and between different CT brands. The availability rather than the clinical need strongly influenced the choice of technique. From the point of view of radiation dose and information necessary for implant planning conventional spiral tomography is to be preferred over reformatted CT. However, when CT is the only technique at hand, it can be performed with a lower than standard mA-setting.

Artifacts↗

PubMedDate not supplied

[Myoelectrical operant conditioning in man].

In the operant conditioning experiment described by HEFFERLINE et al. (1959) a subject terminates or postpones an aversive noise stimulation by producing a particular myoelectrical activity (operant response : OR). These authors observe an increase of OR occurrence frequency in subjects ignoring the aim of the experiment (naive subjects), and they come to the conclusion that this method is efficient. Nevertheless, the validity of this conclusion is questioned by the lack of control experiments. Hence, this work has to be restudied. We have submitted 13 subjects to a control experiment. Subjects were placed under conditions similar to those used by HEFFERLINE et al., but without any contingency relating the myoelectric activity with the aversive stimulus. The results of these open-loop experiments showed that in a given subject, OR occurrence frequency may vary in large proportions as a function of time. In HEFFERLINE's naive subjects, the increase of occurrence frequency remained completely within the limits of spontaneous variations observed in our control subjects. Therefore, this increase is not significant. We have submitted 18 subjects to a conditioning experiment. 14 subjects among them produced more OR than those of the control subjects during the closed-loop experiment. We conclude that these 14 subjects have been actually conditioned.

Avoidance Learning↗

PubMed2004

Intra-specific variation in female remating in Callosobruchus chinensis and C. maculatus.

The effects of mating duration on female remating (exp. 1) and under different male densities (exp. 2) were examined in two strains of the adzuki bean beetle, Callosobruchus chinensis and in one strain of the bruchid beetle, C. maculatus. In experiment 1, the frequency of female remating was markedly different between the two strains of C. chinensis. Females of the jC strain, reared long-term in the laboratory, did not remate after being allowed to mate freely (=monogamy), whereas females of the isC strain, recently established from the field, showed high remating frequencies (=polyandry). In both strains, the frequency of female remating increased after the duration of the first mating was deliberately shortened. The relation between mating duration and remating frequency was significantly different, however, between the two strains. In a closely related species, C. maculatus, which manifests polyandry, this relation was more similar to that of the field-derived (=isC) than to that of the laboratory-derived (=jC) strain of C. chinensis. The reasons for the inter-strain variation observed in the remating frequencies of C. chinensis are also discussed. In experiment 2, the mating duration of the three strains was compared under different male densities. Only the lab-derived strain demonstrated a significantly shorter mating duration when one female was placed together with five males than when paired with one male. The shorter mating duration (approximately 26 s) was similar to that of females allowed to remate in the monogamous strain in experiment 1.

Animals↗

PubMedDate not supplied

[Evaluation of the reduction of the visible plaque index and of the gum bleeding index in a program of oral health promotion for children].

The purpose of this research was to evaluate the reduction of the VPI (visible plaque index) and of the GBI (gum bleeding index) in children seen at a unit of SUS, in the state of Rio de Janeiro. A comparative and statistical procedure (t-test, by means of the GMC program) was employed in order to assess the variation between initial and final mean VPI and GBI values. Initial values were registered in the beginning of the assistance program, and final values were registered after the children had participated in health promotion activities, which included weekly supervised brushing sessions, individual dietary guidance, collective instructive activities in which parents were present, adjusting of the oral environment, as well as restorative and surgical dental care, during an average period of six months. The studied sample comprised fourty-two children, with an average age of nine years, who presented an average of four teeth affected by caries. The technique of indirect documentation, by means of documental research, was employed. The following results were obtained: initial VPI = 29%; final VPI = 11%; initial GBI = 13% and final GBI = 5%. The observed variations were statistically significant at the level of 1%, which was revealed by the applied statistical test. The program proved efficient as to plaque control, reducing VPI to a more acceptable level. Although GBI presented considerable reduction, the presence of bleeding at the end of the program calls for a better approach in motivating patients as to regular oral hygiene.

Adolescent↗

PubMed1981

Analysis of parameters affecting the hemagglutination activity of Escherichia coli possessing colonization factor antigens: improved medium for observing erythrocyte agglutination.

The hemagglutination (HA) activity of two strains of Escherichia coli, each possessing different colonization factor antigens (CFA), was examined under different test conditions. The effects of ionic strength, temperature, pH, cations, and reaction surface on erythrocyte (RBC) agglutination were analyzed. Strain H-10407 (CFA/I) caused the agglutination of human, bovine, and chicken RBC, whereas strain CL-9699 (CFA/II) agglutinated only bovine and chicken RBC. The HA activity of both strains increased with decreasing ionic strength, pH, and temperature, the effects of temperature being negligible at low ionic strength. When accounting for ionic strength, the presence of Ca2+, Mg2+, Fe2+, or Fe3+ ions did not increase the HA activity of these bacteria. Optimum conditions for HA of reactive RBC by bacteria included low ionic strength (less than 50 mM) and slightly acidic pH (6.0 to 7.0). Use of a low-ionic-strength medium permitted application of microtitration methods to visualize the HA reactions. Storage of RBC in low-ionic-strength medium did not change their HA properties, and the use of this medium proved superior to saline in overcoming HA variation observed with different preparations of RBC.

Animals↗

PubMed1978

Regulation of hepatic synthesis of proteins by the chronology of protein ingestion.

Circadian variations in liver protein synthesis were were assessed in control rats fed a mixed 10% protein diet and in rats fed proteins as a separate meal either at 09:00 (SF 09) or at 21:00 (SF 21) and provided with a protein-free diet ad libitum. Protein synthesis was measured by incorporation of labelled leucine over a short period of time (15 min) at time-points regularly spaced over 24 h. In controls, the circadian variations observed were of moderate amplitude (from 2.75 mg/h per g at 09:00 to 5.77 mg/h per g at 06:00) correlated with increased protein and RNA contents of the liver. In separately fed animals ingestion of the protein meal triggered a 300% increase in protein synthesis within 1 h while the feeding pattern was unaltered. In the SF 09 group, high synthetic activity was not followed by an increase of hepatic protein content while hepatic urea concentrations were sharply increased and glucogenic amino acid pools were greatly depleted. It is suggested that the high influx of amino acids consecutive to the absorption of the dietary proteins is the key factor stimulating protein synthesis, while synchronisation with the energetic metabolism controls the degree of degradation. The possible involvement of variations in the insulin to glucagon ratio is discussed.

Amino Acids↗

PubMed2004

Estimation of interindividual variation in oxidative metabolism of dichloromethane in human volunteers.

A modified version of the original physiologically based pharmacokinetic (PBPK) model by Andersen et al. (1987) has been developed and used in conjunction with previously published human kinetic data for dichloromethane (DCM) metabolism and to assess interindividual variability in the rate of oxidative metabolism. Time-course data for 13 volunteers (10 males, 3 females) exposed to one or more concentrations of DCM (50 ppm, 100 ppm, 150 ppm, or 200 ppm) for 7.5h were used to optimize the maximal rate of hepatic metabolism (V(maxC)) through the cytochrome P450 pathway for each individual. DCM breath and blood concentrations were used, along with carboxyhemoglobin concentrations in blood and carbon monoxide (CO) concentrations in exhaled breath, to estimate the model parameters. Significant improvements in model fit were achieved when extrahepatic oxidative metabolism of DCM was added to the model structure. The 13 individual V(maxC) values ranged from 7.1 to 23.6 mg/h/kg0.7 and appeared to be bimodally distributed. The distribution was not sex related and may be related to differential CYP2E1 induction. A comparison of the observed variation in V(maxC) values to other estimates of variability in the rate of oxidative metabolism and human CYP2E1 activity suggest a relatively narrow range in human hepatic activity toward DCM.

Adult↗

PubMed1987

Length of stay for common surgical procedures: variation among districts.

Lengths of stay for appendicectomy, inguinal hernia repair and cholecystectomy for the 16 districts in the Northern Regional Health Authority (NRHA) and 15 districts in the South East Thames Regional Health Authority (SETRHA) are examined using data recorded in the Hospital Activity Analysis. Considerable variations exist among districts, with the three longest stay districts for each procedure in NRHA having an age-adjusted length of stay of 113 per cent of the regional average for appendicectomy, 125 per cent for hernia and 115 per cent for cholecystectomy. This resulted in greater than 2000 additional bed days per year being occupied in the three longest stay districts in the NRHA compared with the regional average. The age adjusted length of stay for the three shortest stay districts for each procedure is 83 per cent of the regional average for appendicectomy, 75 per cent for hernia and 85 per cent for cholecystectomy. Similar differences are seen in the SETRHA, and derive from differences in the length of both preoperative and postoperative stay. Explanations for the observed variations are considered in terms of population, organizational and clinical variables.

Adolescent↗

PubMed2004

Community-acquired pneumonia: influence of management practices on length of hospital stay.

AIMS: To identify variation in the management of -community-acquired pneumonia between two New Zealand hospitals and the factors that may account for any differences. METHODS: A 12-month, prospective two-centre study was conducted. Between July 1999 and July 2000, 474 adult patients with community-acquired pneumonia were enrolled: 304 in Christchurch Hospital and 170 in Waikato Hospital. The patients were similar in age, sex, prior antibiotic use and comorbidity. There was no significant difference in the clinical outcomes for the patients at the two centres. RESULTS: The mean duration of i.v. antibiotic therapy was 1.7 versus 3.0 days (P < 0.001) and length of stay (LOS) was 3.0 versus 5.9 days (P < 0.001) for Waikato and Christchurch Hospitals, respectively. Using multivariate analysis, we could account for 61% of the observed variation in LOS. Duration of i.v. antibiotic therapy independently accounted for 16% of variation in LOS compared with age (2%), chronic obstructive pulmonary disease, duration of fever, intensive care unit admission and centre of admission (all <1%). For the duration of i.v. antibiotics, centre of admission, largely reflecting clinician practice at each centre, independently accounted for 13% of variation, compared with duration of fever (5%), admission to the Intensive Care Unit (4%), Pneumonia Severity Index score (3%) and bacteraemia (3%). CONCLUSION: Of the identifiable factors, variations in clinician behaviour outweighed the influence of patient factors on the duration of i.v. antibiotic therapy, which in turn was the major determinant of LOS for patients hospitalised with community-acquired pneumonia. An early switch from i.v. to oral antibiotic therapy in conjunction with early discharge planning may significantly reduce LOS without compromising patient outcomes.

Aged↗

PubMed1998

Flagellin gene variation between clinical and environmental isolates of Burkholderia pseudomallei contrasts with the invariance among clinical isolates.

The flagellin gene sequence from a clinical isolate of Burkholderia pseudomallei was used to design oligonucleotide primers for PCR/RFLP analysis of flagellin gene variation among clinical and environmental isolates of B. pseudomallei. Genes from four clinical and six environmental isolates were amplified and compared by RFLP. The clinical isolates were indistinguishable, but variation was detected among some of the environmental isolates. Sequence analysis of flagellin gene amplified products demonstrated high levels of conservation amongst the flagellin genes of clinical isolates (>99% similarity), compared to the variation observed between the clinical isolates and one of the environmental isolates (<90% similarity). Genomic comparisons with pulsed-field gel electrophoresis (PFGE) revealed differences between the relationships inferred by flagellin genotyping and PFGE, suggesting that a combination of molecular methods may be useful for the subtyping of B. pseudomallei strains.

Bacterial Outer Membrane Proteins↗