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PubMed1998

[Role of stress myocardial perfusion scintigraphy in the follow-up of patients undergoing coronary angioplasty: comparison between qualitative and semi-quantitative analysis].

In order to assess the diagnostic accuracy of stress/rest myocardial perfusion scintigraphy in the follow-up of patients undergoing percutaneous transluminal coronary angioplasty (PTCA) we studied 50 patients (pts) before and 6 months after PTCA. All patients underwent control coronary angiography and then were divided in 2 groups, according to angiographic evidence of restenosis (25 pts) or no restenosis (25 pts). Myocardial perfusion imaging was performed with 99mTc-methoxy-isobutyl-isonitrile (MIBI). For MIBI scans, both qualitative and semi-quantitative analysis were performed. SPECT images were displayed on a color monitor in random order and graded blindly by 2 experienced observers. Rest and stress MIBI uptake was scored using a 4-point scale (ranging from 0 = normal, to 3 = absence of uptake). Individual subjects' perfusion scores were calculated by adding the individual segments' scores. History of relapsing angina showed a sensitivity and specificity of 76 and 96%, respectively. Exercise testing and MIBI tomoscintigraphy exhibited sensitivity and specificity of 80 and 56%, and 92 and 44%, respectively. However, when considering semiquantitative data and comparing them with pre-PTCA studies, specificity of MIBI scan increased to 96%, while sensitivity decreased to 72%. The results of the present study confirm high sensitivity and low specificity for both exercise ECG and myocardial perfusion scintigraphy, in the detection of restenosis following PTCA. However, when performing semiquantitative analysis of perfusion scanning and comparison with pre-PTCA images, the specificity of MIBI tomoscintigraphy increases significantly. Therefore, when adopting myocardial perfusion scintigraphy for the follow-up of patients undergoing PTCA, a pre-revascularization scan should be obtained as often as possible. This approach, in the context of a positive test, makes feasible the assessment of often partial improvements in perfusion of the myocardium relative to the treated vessel, consequently avoiding many false positive results which invariably lead to coronary angiography.

Aged↗
PubMed1987

Quantitative analysis of the molar-size sequence in human prehistoric populations of the Canary Isles.

Percentage frequencies for molar-size sequence of first and second molars, as well as the statistical parameters for the individual differences between the measurements of these molars, were calculated in two human prehistoric aboriginal samples from Gran Canaria and Tenerife Islands using mesiodistal and buccolingual dimensions. Remarkable differences between the two populations, whose cultural and anthropological differences are well established, were observed. The findings support the hypothesis that quantitative analysis of molar size sequence can be useful in establishing phylogenetic relationships between populations.

Atlantic Islands↗
PubMed1979

Quantitative analysis of intermediary metabolism in Tetrahymena. Cells grown in proteose-peptone and resuspended in a defined nutrient-rich medium.

Tetrahymena pyriformis were grown to early-stationary phase and resuspended in a defined mixture containing glucose, fructose, ribose, glycerol, acetate, pyruvate, bicarbonate, glutamate, and hexanoate, with only one substrate labeled with 14C in any flask. Incorporation of label into CO2, glycogen, RNA, alanine, glutamate, glycine, lipid glycerol, and lipid fatty acids was measured 20, 40, and 60 min after the start of the incubation. To develop a model suitable for quantitative analysis of the data, it was necessary to join two preceding models, one for carbohydrate-metabolizing cells and one for acetate-metabolizing cells, eliminating the over-simplified sections of each. Equations were written and programmed for a digital computer to allow computation of the amount of label expected to be incorporated into any of the products measured for any given set of steady state flux values in the metabolic network. The model formed by simply joining the two preceding models did not yield satisfactory agreement with the complete data obtained in the present study, although each partial set of data could be fit well by the appropriate partial model. Analysis of the ways in which the model failed to yield good fits to the data indicated that another pool of P-enolpyruvate, of pyruvate, and of acetyl-CoA had to be added at the junction of the two models. The presence of such poolte into fatty acids as compared to the incorporation of label from glucose into fatty acids. A new model was therefore constructed which differed from the preceding model only in its structural organization at the level of P-enolpyruvate, pyruvate, and acetyl-CoA. The model is consistent with all known information on the compartmental structure of metabolism in Tetrahymena, on enzyme localization, and on the enzyme complement of this cell. Over 70 measurements of label incorporation into products were made at each time. These, plus a large number of "limit" measurements which constrain any possible solutions, were in sufficient excess of the 39 independent flux values to permit a stringent assessment of the model. A set of flux values was found which yielded a good fit to the data. These flux values therefore provide a quantitative description of metabolite flux in the intact cell during the slow adaptation to the nine-substrate mixture. The rates of utilization of glucose, fructose, glycerol, and ribose were in the ratio of about 10:1:0.33:0.16, i.e. fairly similar to the ratio observed with carbohydrate-metabolizing cells. Initial flux through phosphofructokinase is about 160 nmol/10(6) cells.h, increasing over 3-fold during tje jpir incubation. Initial flux through fructose-1,6-diphosphatase is about 110 nmol/10(6) cells.h and also increases almost 3-fold during the incubation. Thus net flux is glycolytic and increases 4-fold during the hour with a large amount of futile cycling at this step...

Acetates↗
PubMed2005

Evaluating hormone therapy-associated increases in breast density comparison between reported and simultaneous assignment of BI-RADS categories, visual assessment, and quantitative analysis.

RATIONALE AND OBJECTIVES: Changes in breast density, which are commonly associated with hormone replacement therapy (HRT) use, may imply changes in breast cancer risk. This study explores the ability of different methods to detect hormone replacement therapy (HRT)-associated increases in breast density. MATERIALS AND METHODS: Between 1997 and 2001, 51 postmenopausal women were reported to have HRT-associated increases in breast density at our institution. Twenty postmenopausal women not reported to have an increase in density during the same period were selected as controls. Mammograms from date of report and earlier comparison were used. Breast Imaging Reporting and Data System (BI-RADS) density categories from both dates were obtained from the mammography report. Mammograms were reviewed at separate time points and density changes evaluated by assigning BI-RADS density categories, visual assessment, and computer-assisted quantitative analysis. RESULTS: Mammogram reports were not available for two patients. The remaining 49 women with reported HRT increases in density were included. Reported BI-RADS categories resulted in detection of 57%, simultaneous BI-RADS assignment in 61%, visual assessment in 100%, and quantitative assessment in 94% of women with HRT-associated increases in density. Reported BI-RADS category change was the only method that resulted in false-positive increases in density for control patients. Minimal HRT associated increases in density were the most difficult to detect, with 90% of these 21 cases not detected by simultaneous BI-RADS category assignment and 3 cases not detected by quantitative methods when defined as an increase of at least 5%. CONCLUSION: Visual and quantitative assessment best identified women with HRT-associated increases in density, including those with minimal increases. Simultaneous assignment of BI-RADS categories was considerably better than use of reported BI-RADS categories. This information may be helpful in guiding research design of studies evaluating changes in density from the HRT use.

Adult↗
PubMed2005

Quantitative analysis of beta-blockers in pharmaceutical preparations by capillary electrophoresis.

A simple capillary electrophoresis method was developed for the analysis of four beta-blockers (atenolol, metoprolol, pindolol, and propranolol) in pharmaceutical preparations. The method was validated regarding accuracy, precision, linearity, and detection/quantification limits, and the obtained values were in accordance to those reported in the literature. The method was applied to the determination of the drugs in commercial tablet preparations and proved to be fast and reliable for the quantitative analysis of the beta-blockers.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Spinal cord transection: a quantitative analysis of elements of the connective tissue matrix formed within the site of lesion following administration of piromen, cytoxan or trypsin.

Long-Evans hooded rats were cordotomized at the T-5 level and given either (1) cyclophosphamide (cytoxan), an immunosuppressive, (2) piromen, a bacterial polysaccharide-nucleic acid complex, (3) topical and systemic trypsin, or (4) no further specific treatment. Because of past and present controversy surrounding the proposed ability of these agents to promote spinal cord regeneration, a systematic study, employing light and electron microscopy, and quantitative methods in a single animal model, was done in order to re-evaluate the effects of each treatment upon the connective tissue matrix which forms in the defect left by transection. After an initial inflammatory reaction during the first week after surgery, the lesion zone is characterized either by areas of dense collagenous connective tissue with occasional fibroblasts and macrophages, or a loose areolar tissue with numerous sheets and cords of mesodermal cellular elements but minimal collagen. By 45 days postoperatively (dpo), axons supported by Schwann cells invade and become entangled in the loose connective tissue matrix. With longer postoperative survival, cysts appear craniad and caudad to the lesion and erode much of the scar together with viable neural tissue. Giving cytoxan or piromen did not result in any qualitative alteration of the scar matrix as evidenced by electron microscopy. Quantitative analysis revealed a slight reduction in the fibrous connective tissue component of the scar at 45--90 dpo, but this was transient when longer postoperative periods were studied. Trypsin caused a significant reduction in the amount of fibrous connective tissue with a concomitant increase in loose connective tissue and the appearance of a few distinctive, compact bundles of unmyelinated axons lacking Schwann cells. Consistent behavioral changes were not observed in any group which could distinguish them from the controls. Our results appear to contradict the findings of Matinian and Andreasian (1976) who reported return of normal sensori-motor function in 80% of their animals treated with topical and systemic trypsin. It is concluded that a major impediment to whatever longterm regenerative potential exists within the spinal cord is the lack of axonal guiding elements within the scar, but more importantly, the severe erosion of the remaining spinal cord due to cyst enlargement.

Animals↗
PubMed2005

A quantitative analysis of fish consumption and coronary heart disease mortality.

Although a rich source of n-3 polyunsaturated fatty acids (PUFAs) that may confer multiple health benefits, some fish contain methyl mercury (MeHg), which may harm the developing fetus. U.S. government recommendations for women of childbearing age are to modify consumption of high-MeHg fish to reduce MeHg exposure, while recommendations encourage fish consumption among the general population because of the nutritional benefits. The Harvard Center for Risk Analysis convened an expert panel (see acknowledgements) to quantify the net impact of resulting hypothetical changes in fish consumption across the population. This paper estimates the impact of fish consumption on coronary heart disease (CHD) mortality and nonfatal myocardial infarction (MI). Other papers quantify stroke risk and the impacts of both prenatal MeHg exposure and maternal intake of n-3 PUFAs on cognitive development. This analysis identified articles in a recent qualitative review appropriate for the development of a dose-response relationship. Studies had to satisfy quality criteria, quantify fish intake, and report the precision of the relative risk estimates. Relative risk results were averaged, weighted proportionately by precision. CHD risks associated with MeHg exposure were reviewed qualitatively because the available literature was judged inadequate for quantitative analysis. Eight studies were identified (29 exposure groups). Our analysis estimated that consuming small quantities of fish is associated with a 17% reduction in CHD mortality risk, with each additional serving per week associated with a further reduction in this risk of 3.9%. Small quantities of fish consumption were associated with risk reductions in nonfatal MI risk by 27%, but additional fish consumption conferred no incremental benefits.

Adult↗
PubMed2001

Quantitative analysis of apical root resorption by means of digital subtraction radiography.

OBJECTIVE: This study was performed to assess the diagnostic and quantifying ability of digital subtraction images for simulated apical root resorption, as well as to compare the diagnostic accuracy of conventional intraoral radiographs with digital subtraction images for this condition. STUDY DESIGN: Digital and intraoral radiographs of 10 sound maxillary central incisors and those with simulated apical root resorption were taken with varying horizontal and vertical angulations of the x-ray beam. Paired t tests were used to compare the lengths of the sound teeth on the images with their actual lengths, and the estimated amount of simulated apical root resorption was compared with the actual amount of tooth loss by means of Emago software. The diagnostic accuracy for detecting lesions was also evaluated on conventional intraoral radiographs and digital subtraction images through receiver operating characteristic (ROC) analysis. RESULTS: There were no statistically significant differences between the actual lengths and those measured on the reconstructed images of the sound teeth. The calculated amounts of apical root resorption showed no statistically significant differences in comparison with the actual amounts (P >.05). The diagnostic accuracy of the conventional intraoral radiographs in detecting the lesions was low (ROC area = 0.6446). CONCLUSION: A quantitative analysis of small amounts of apical root resorption can be performed by means of digital subtraction radiography.

Humans↗
PubMed2006

[Morphologic quantitative analysis of nucleus in laryngeal squamous cell carcinoma with Automatic Image Cytometry].

OBJECTIVE: Analyze morphological character of nucleus in laryngeal squamous cell carcinoma with Automatic Image Cytometry, discuss the relation between morphological parameters and tumor clinic. METHOD: We discussed morphological character of nucleus from 83 cytology specimens which included 21 laryngeal squamous cell carcinomas and 20 benign diseases with Automatic Image Cytometry. RESULT: Nucleus from laryngeal squamous cell carcinomas had bigger nuclear area nuclear radius, nuclear perimeter and more DNA content per nuclear area than from laryngeal benign diseases, furthermore, these parameters showed distinct difference in different anatomic positions and different pathologic types. We concluded that nuclear areas of nucleus in S phase from laryngeal squamous cell carcinomas are more than 77 microm, Second Order Regression Equation(Y =aX2+bX+c) described scattered diagrams between mean nuclear radius and nuclear area of laryngeal cytology specimens with different larynx pathology and different cell phase in cell cycle. The more the value of coefficient "c"(c>1.82) and the less the value of coefficient "b" (b< 0.045), the more the probability of malignant tumor diagnosis. CONCLUSION: Morphologic quantitative analysis parameters, such as nuclear area, mean nuclear radius, nuclear perimeter and DNA content per nuclear area, are suitable for diagnosing laryngeal squamous cell carcinomas. They could offer valuable morphologic quantitative criterion in assisting cytology diagnose and evaluating tumor clinical characters when these parameters associated with nuclear area of nucleus in S-phase and the coefficients of Second Order Regression Equation.

Carcinoma, Squamous Cell↗
PubMed1989

Nasopharyngeal culture with quantitative analysis of pathogenes in chronic otitis media with effusion. Effects on pathogen yield of different swabs and transport methods.

The influence of different swabs and transport media on nasopharyngeal culture pathogen recovery has been studied in patients with chronic otitis media with effusion. Transport times of less than two hours have been used. Protecting the cotton wire swab with a polyethylene shealth to prevent contamination by nasal flora did not have any significant influence either on the recovery of potential pathogens or on the contaminating nasal flora. Facilitating a quantitative analysis of the nasopharyngeal culture by transporting the specimen in empty tubes gave a pathogen recovery rate similar to that with transport in Stuart medium, whereas an attempt at transporting in sodium chloride or prereduced PY broth led to significantly lower yields of Branhamella catarrhalis (p less than 0.01) and in PY broth on Haemophilus influenzae as well (p less than 0.01).

Child, Preschool↗
PubMed2000

Quantitative analysis of estrogen receptor-alpha and -beta messenger RNA expression in breast carcinoma by real-time polymerase chain reaction.

BACKGROUND: Estrogen action is mediated not only through a classic estrogen receptor (ER) (ER-alpha) but also through a second ER (ER-beta) that has a structure and function similar to ER-alpha. A correlation between ER-beta mRNA expression with ER and progesterone receptor (PR) protein levels as well as prognostic factors remains to be established in breast carcinoma. METHODS: The authors conducted a quantitative analysis of ER-alpha and ER-beta mRNA expression in 116 breast tumors using real-time polymerase chain reaction (PCR), and investigated a possible correlation between ER-alpha and ER-beta mRNA expression and ER and PR status as determined by enzyme immunoassay as well as with various prognostic factors. RESULTS: ER-alpha mRNA levels were significantly (P < 0.01) higher in ER positive compared with ER negative tumors. Conversely, ER-beta mRNA levels were significantly (P < 0.01) lower in ER positive compared with ER negative tumors. Accordingly, the ratio of ER-beta to ER-alpha was significantly (P < 0.01) higher in ER negative compared with ER positive tumors. A subset analysis based on ER and PR status showed that ER-beta mRNA levels as well as the ratios of ER-beta to ER-alpha mRNA level were highest in ER negative and PR negative tumors (P < 0.05). ER-alpha mRNA levels were significantly (P < 0.05) higher in postmenopausal compared with premenopausal tumors. Histologic Grade 3 tumors showed a significant decrease in ER-alpha mRNA levels compared with Grade 1 and 2 tumors (P < 0.01 and P < 0.05, respectively). No significant correlation between ER-alpha and ER-beta mRNA levels and histologic type, tumor size, or lymph node status was observed. CONCLUSIONS: An absolute and relative increase in ER-beta mRNA levels in ER negative and PR negative breast tumors, which rarely respond to endocrine therapy, suggests the possible involvement of up-regulation of ER-beta mRNA in the development of estrogen-independent tumors.

Adult↗
PubMed1981

Quantitative analysis of melphalan and its major hydrolysate in patients and animals by reversed-phase high-performance liquid chromatography.

The detection of 4-bis-(2-hydroxyethyl)amino-1-phenylalanine (L-DOH) in blood samples taken from patients after treatment with melphalan [4-bis-(2-chloroethyl)amino-1-phenylalanine, L-PAM] suggests that the quantification of this major hydrolysate of L-PAM can be of considerable importance in L-PAM chemotherapy. A reversed-phase high-performance liquid chromatographic procedure has been developed for the quantitative analysis of both L-PAM and L-DOH in biological samples, with a detection sensitivity of 0.1 ppm. This method provides a distinct separation of L-PAM (retention time 12 min) and L-DOH (retention time 6.5 min), with no interference from the biological background (retention time 1.4--3 min).

Animals↗
PubMed1993

Quantitative analysis of mitotic and early-G1 cells using monoclonal antibodies against the AF-2 protein.

We have recently described a novel protein (AF-2), conserved between fission yeast and man, and we have shown by flow cytometry (FCM) that AF-2 is highly accessible to specific monoclonal antibodies (MoAbs) in mitotic and postmitotic early-G1 phase cells. The aim of the present study was to optimize the FCM methodology using MoAbs against AF-2 and to show that the evaluation of the mitotic cells, using different cell lines, was quantitative and reproducible. We found that a method based on fixation with ethanol, instead of formalin, resulted in improved DNA histogram coefficients of variation and implemented separation of early-G1 cells from late-G1 cells. In addition, by eliminating several cell permeabilization and protein salt extraction steps, the method became straightforward, conserved a clear-cut separation of the green fluorescence of M- with respect to G2-phase cells, and did not significantly affect cellular integrity. The coefficient of correlation among the mitotic index values evaluated by this FCM method using MoAbs against AF-2 and by microscopic visual counting was R = 0.94. When the FCM/AF-2 method was tested against an independent FCM method, which allows clear separation of M- and G2-phase cells according to 90 degrees scattering, we found R = 0.93. We conclude that MoAbs against the AF-2 protein may be used in FCM for quantitative analysis and for isolation of M-phase cells, providing as well, the identification of the early-G1 cell subcompartment. The method may, in addition, be useful for the simultaneous detection of cytoplasmic cytokeratin and nuclear AF-2 antigen.

Antibodies, Monoclonal↗
PubMed2005

Quantitative analysis of the 26 allergens for cosmetic labeling in fragrance raw materials and perfume oils.

The adoption of the 7th amendment of the European Cosmetic Directive 76/768/EEC requires any cosmetic product containing any of 26 raw materials identified by the Scientific Committee on Cosmetic Products and Non-Food Products intended for Consumers as likely to cause a contact allergy when present above certain trigger levels to be declared on the package label. Of these 26, 24 are volatile and can be analyzed by GC. This paper describes a method for the quantitative analysis of these volatile raw materials in perfume ingredients as well as complex perfume compositions. The method uses sequential dual-column GC-MS analysis. The full-scan data acquired minimize the false-positive and false-negative identifications that can be observed with alternate methods based on data acquired in the SIM mode. For each sample, allergen levels are determined on both columns sequentially, leading to two numerical results for each allergen. Quantification limits for each allergen in a perfume mixture based on the analysis of a standard are <4 mg/kg. This is well below the level that would trigger label declaration on the consumer good. Calibration curves for all allergens are linear (r > 0.999) and stable for multiple days. Studies on perfumes spiked with multiple allergens at 30, 50, and 70 mg/kg show recoveries close to nominal values.

Allergens↗
PubMed2000

[HPLC quantitative analysis of berberine absorpted with macroporous resin in Rhizoma Coptidis and its preparation zuo jin wan].

Absorptive ability and elution program of macroporous resin to the berberine in the Rhizoma Coptidis and its preparation Zuo Jin Wan (containing Rhizoma Coptidis and Fructus Evodiae) were explored. The extract of 70% MeOH of samples were disolved in water, then alkalized to pH 12 with ammonia solution. The berberine was absorpted by the macroporous resin, the washed off water soluble impurity with alkalescent water, and eluted with 50% MeOH containing 0.5% H2SO4. The results of quantitative analysis of the berberine by HPLC were satisfied.

Adsorption↗
PubMed2007

Quantitative analysis in outcome assessment of instrumented lumbosacral arthrodesis.

The outcome assessment in instrumented lumbosacral fusion mostly focuses on clinical criteria, complications and scores, with a high variability of imaging means, methods of fusion grading and parameters describing degenerative changes, making comparisons between studies difficult. The aim of this retrospective evaluation was to evaluate the interest of quantified radiographic analysis of lumbar spine in global outcome assessment and to highlight the key biomechanical factors involved. Clinical data and Beaujon-Lassale scores were collected for 49 patients who underwent lumbosacral arthrodesis after prior lumbar discectomy (mean follow-up: 5 years). Sagittal standing and lumbar flexion-extension X-ray films allowed quantifying vertebral, lumbar, pelvic and kinematic parameters of the lumbar spine, which were compared to reference values. Statistics were performed to assess evolution for all variables. At long-term follow-up, 90% of patients presented satisfactory clinical outcomes, associated to normal sagittal alignment; vertebral parameters objectified adjacent level degeneration in four cases (8%). Clinical outcome was correlated (r = 0.8) with fusion that was confirmed in 80% of cases, doubtful in 16% and pseudarthrosis seemed to occur in 4% (2) of cases. In addition to clinical data (outcomes comparable to the literature), quantitative analysis accurately described lumbar spine geometry and kinematics, highlighting parameters related to adjacent level's degeneration and a significant correlation between clinical outcome and fusion. Furthermore, criteria proposed to quantitatively evaluate fusion from lumbar dynamic radiographs seem to be appropriate and in agreement with surgeon's qualitative grading in 87% of cases.

Adult↗
PubMed2002

Structural and quantitative analysis of astrocytes in the mouse hippocampus.

We revealed the structural features of astrocytes by means of light microscopy, confocal laser scanning microscopy and high voltage electron microscopy, and estimated their numerical densities in the mouse hippocampus. The high voltage electron microscope examinations of Golgi-impregnated astrocytes clearly disclosed their fine leaflet-like processes in the masses occupied by individual astrocytes. The intracellular injection of two different fluorescent tracers into two neighboring astrocytes revealed that each astrocyte occupied a discrete area with a limited overlap only at its peripheral portion. In a quantitative analysis using an optical dissector, the numerical densities of astrocytes identified as S100-immunoreactive cells were only slightly different in their areal and laminar distributions. The numerical densities were higher in the stratum lacunosum-moleculare and dentate hilus, while they were slightly lower in the principal cell layers than the average (24.2 x 10(3) mm(-3)) in whole hippocampal regions. As for the dorsoventral difference, the numerical densities were significantly larger at the ventral level in the dentate gyrus, whereas such tendency was not apparent in the hippocampus proper. The projection area of the astrocytes estimated from Golgi-impregnated samples was roughly in inverse relation to the numerical densities; the areas in the stratum lacunosum-moleculare were somewhat smaller than the other layers, where the numerical densities were high. The present study indicates that astrocytes are distributed rather evenly without any prominent areal or laminar differences and that the individual astrocytes have their own domains; the periphery of the domain of a given astrocyte is interdigitated intricately with the processes of adjacent astrocytes whereas its inner core portion is not penetrated by them.

Animals↗
PubMed2006

Quantitative analysis of dental microwear in threespine stickleback: a new approach to analysis of trophic ecology in aquatic vertebrates.

1. The threespine stickleback Gasterosteus aculeatus is an important model organism in studies of genomic and phenotypic evolution, adaptation and speciation. Fossil Gasterosteus offer the potential to test models derived from studies of extant fishes over true evolutionary time-scales. Competition for food resources, for example, plays an important part in stickleback speciation, causing divergence in food gathering traits and ecological character displacement, but it is not possible to test this model in fossils because evidence of diet is almost never preserved. 2. We demonstrate here that quantitative analysis of dental microwear, a technique previously applied only to mammals, provides a reliable guide to the dietary preferences of stickleback. Teeth from stickleback raised under laboratory conditions exhibit microwear patterns that vary systematically according to substrate coarseness and whether fishes feed on Daphnia within the water column, or on chironomid larvae from the bottom. Furthermore, microwear data exhibit a progressive shift in their distribution that tracks differences in experimental feeding treatments. 3. Microwear in wild populations also exhibits a relationship with feeding. In blind assessments of trophic niche based on microwear patterns we were able to correctly assign all but one equivocal population to trophic group. Microwear data from wild stickleback exhibit a shift in distribution comparable with that observed across the range of treatments in the laboratory and these allow populations to be ranked according to the degree to which they approach fully benthic or fully limnetic feeding. 4. Our results demonstrate that microwear has the potential to be a powerful tool in the analysis of fish trophic ecology, particularly in the analysis of species pairs and niche differentiation. It has advantages over the trophic snapshot provided by analysis of stomach contents in that microwear reflects feeding and food preferences over a longer period of time, and can be applied where these data are unavailable. Furthermore, it is applicable to extinct organisms and fossils, allowing the role of trophic ecology, niche partitioning and competition over evolutionary time-scales to be investigated for the first time.

Animals↗