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Biomedical subjects

A Bright

Publications and source records attributed to A Bright.

9 recordsLinked to original sources
PubMed2004

Bill colour and correlates of male quality in blackbirds: an analysis using canonical ordination.

Carotenoid-dependent plumage displays are widely assumed to be honest indicators of individual health or quality, which are used as cues during mate choice and/or agonistic signalling. Despite the fact that red, yellow and orange pigmentation of bills is common, and also variable between individuals, comparatively little is known about bill colouration as a condition-dependent trait. Furthermore, many studies of avian colouration are confounded by the lack of objective colour quantification and the use of overly simplistic univariate techniques for analysis of the relationship between the condition-dependent trait and individual quality variables. In this study, we correlated male blackbird bill colour (a likely carotenoid-dependent sexually selected trait) with body/condition variables that reflect male quality. We measured bill colour using photometric techniques, thus ensuring objectivity. The data were analysed using the multivariate statistical techniques of canonical ordination. Analyses based on reflectance spectra of male blackbird bill samples and colour components (i.e. hue, chroma and brightness) derived from the reflectance spectra were very similar. Analysing the entire reflectance spectra of blackbird bill samples with Redundancy Analysis (RDA) allowed examination of individual wavelengths and their specific associations with the body/condition variables. However, hue, chroma and brightness values also provided useful information to explain colour variation, and the two approaches may be complimentary. We did not find any significant associations between male blackbird bill colour and percent incidence of ectoparasites or cloaca size. However, both the colour component and full spectral analyses showed that culmen length explained a significant amount of variation in male blackbird bill colour. Culmen length was positively associated with greater reflectance from the bill samples at longer wavelengths and a higher hue value (i.e. more orange-pigmented bills). Larger males may have larger territories or be better at defending territories during male-male interactions, ensuring access to carotenoid food sources. Future studies should elucidate the relationship between bill colour and behavioural measures such as aggressiveness, territory size, song rate and nest attendance.

Animals↗
PubMed2001

The effects of voluntary contraction intensity and gender on perceived exertion during isokinetic quadriceps exercise.

The objectives of the present study were to: (1) examine perceived exertion across different target voluntary contraction intensities, (2) compare perceived exertion ratings with actual target intensities, and (3) compare perceived exertion ratings between males and females. The subjects for this study included 30 healthy, college-aged male (n = 15) and female (n = 15) volunteers. All subjects were free of orthopedic, cardiopulmonary, systemic and neurological disease. Each subject completed five maximal isokinetic, concentric quadriceps contractions in a seated position at 60 degrees.s-1 to determine their single, highest peak torque. All subjects then completed, in a random order, 3-5 submaximal isokinetic contractions at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of their single, highest peak torque. Each relative contraction level (i.e., percentage) was achieved by having the subjects attempt to match the peak of their torque curve to a horizontal line on a computer monitor. Perceived exertion was measured by asking the subjects to provide a number that corresponded to the feelings in their quadriceps during exercise by viewing a modified category-ratio (CR-10) scale. The results of a two-factor (gender x intensity) analysis of variance revealed a significant, intensity main effect (F8,232 = 92.19, P < 0.001, eta 2 = 0.77, 1 - beta = 0.99) and no significant gender main effect (F8,232 = 2.66, P = 0.11, eta 2 = 0.09, 1 - beta = 0.35) or interactions (F8,232 = 1.01, P = 0.43, eta 2 = 0.04, 1 - beta = 0.46). The findings of this study demonstrate that perceived exertion is significantly (P < 0.05) different from the specific target values on the CR-10 scale at 10%, and 50-90% maximum voluntary contraction. The results revealed that the increase in perceived exertion across the contraction intensities could be fit to both linear (F1,29 = 205.41, P < 0.001, eta 2 = 0.88, 1 - beta = 0.99) and quadratic (F1,29 = 10.05, P = 0.004, eta 2 = 0.26, 1 - beta = 0.87) trends. These findings suggest that perceived exertion is underestimated during submaximal isokinetic exercise, and is not different between males and females.

Adult↗
PubMed2001

Influence of contraction intensity, muscle, and gender on median frequency of the quadriceps femoris.

The purpose of this study was to assess the effects of contraction intensity, gender, and muscle on median frequency of the three superficial portions of the quadriceps femoris muscle. Thirty healthy volunteers were assessed for isometric electromyogram activity of the vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) muscles with the knee at 60 degrees flexion. Subjects performed 5-s isometric contractions at 10, 20, 30, 40, 50, 60, 70, 80, and 90% of the average of three maximal voluntary contractions. Median frequency (f(med)) of the three muscles was assessed through a power spectral analysis performed over 11 consecutive 512-ms epochs overlapping each other by one-half their length. The f(med) for each of the 11 epochs was then determined, followed by calculation of the mean and SD. The major findings of this study demonstrated that overall f(med) was significantly highest for the VL and lowest for the VM, whereas RF f(med) was between that of the other two muscles. Similar findings were observed for f(med) variability as the VL was significantly higher than the VM and RF, with no gender differences or differences between the latter two muscles. The results demonstrate that the largest change in f(med) as a function of contraction intensity occurred for the VL in men (18.6%) and women (7.6%). These findings suggest that muscle fiber-type homogeneity may exist in the VM and RF, which displayed negligible changes in f(med), whereas the VL may possess greater morphological variability.

Adult↗
PubMed2000

Dual sugar permeability testing in diarrheal disease.

OBJECTIVE: To assess the validity of the use of a blood specimen for the sugar permeability test because of the high failure rate of 5-hour urine collection in young children with diarrhea. STUDY DESIGN: Simultaneous 5-hour urine collections and timed blood tests were taken after ingestion of an isotonic solution of lactulose (L) and L-rhamnose (R) in 24 children with acute gastroenteritis and 25 children without diarrhea in a control group. Sugars were measured with high performance liquid chromatography, and the percent of recovered sugars was expressed as an L-R ratio. RESULTS: With acute gastroenteritis the geometric mean L-R ratios (95% confidence intervals) were 12.4 (9.3 to 16.3) in urine and 9.4 (6.7 to 13.1) in blood compared with 6.7 (5.0 to 8.8) and 5.9 (4.4 to 7.8), respectively, in the control group. The level of agreement (kappa) among normal, intermediate, and high ratios for blood and urine was 0.71 (0.51 to 0.92). The failure rate of L-R tests was significantly reduced with a blood specimen (urine 37% vs blood 10%; P <.0001). CONCLUSIONS: Intestinal permeability testing on a blood specimen is a valid alternative to urine collection in young children and has a significantly lower test failure rate.

Blood Specimen Collection↗
PubMed1999

Intestinal permeability and diarrhoeal disease in Aboriginal Australians.

BACKGROUND: Northern Territory Aboriginal children hospitalised with acute gastroenteritis have high rates of acidosis, hypokalaemia, and dehydration. AIMS: To determine whether Aboriginal children with and without diarrhoea have greater impairment in intestinal function than non-Aboriginal children, as assessed by increased permeability ratios. METHODS: A descriptive study of 124 children (96 Aboriginal and 28 non-Aboriginal) hospitalised with and without diarrhoea. Intestinal permeability was assessed by the lactulose to rhamnose (L-R) ratio from a five hour urine collection. RESULTS: In Aboriginal children, mean L-R ratios (95% confidence intervals) were 18.3 (17.1 to 19.6) with diarrhoea and 9.0 (7.3 to 11.0) without diarrhoea, and in non-Aboriginal children they were 5.9 (2.8 to 12. 3) and 4.2 (3.3 to 5.2), respectively. In patients with diarrhoea, L-R ratios were significantly raised when accompanied by acidosis (mean, 22.8; 95% CI, 17.0 to 30.5), hypokalaemia (mean, 20.7; 95% CI, 15.4 to 27.9), and >/= 5% dehydration (mean, 24.3; 95% CI, 19.0 to 29.6) compared with none of these complications (mean, 7.0; 95% CI, 3.5 to 13.8). CONCLUSION: The high incidence of acidosis, hypokalaemia, and dehydration in Aboriginal children admitted with diarrhoeal disease is related to underlying small intestinal mucosal damage.

Acidosis↗
PubMed1989

Oligosaccharide differences in the DF3 sialomucin antigen from normal human milk and the BT-20 human breast carcinoma cell line.

The murine monoclonal antibody DF3, prepared against a membrane-enriched fraction of a human breast carcinoma, recognized high molecular weight mucin-like glycoproteins from normal human milk and breast carcinoma cell lines. Although the epitope recognized appeared to be a peptide segment, recognition was altered by neuraminidase, suggesting carbohydrate contributions to antigen recognition. Examination of DF3 antigen isolated from normal human milk and the BT-20 human breast carcinoma cell line showed significant oligosaccharide differences. DF3 antigen from BT-20 cells contained three major oligosaccharides, the peanut agglutinin-binding disaccharide Gal beta 1,3GalNAc, which is the carbohydrate component of the Thomsen-Friedenreich antigen, and its mono-(NeuAc2,3Gal beta 1,3GalNAc and/or Gal beta 1,3(NeuAc alpha 2,6)GalNAc) and disialylated (NeuAc2,3Gal beta 1,3(NeuAc alpha 2,6)GalNAc) derivatives. In contrast, the DF3 antigen from normal human milk contained the tetrasaccharide Gal beta 1,4GlcNASc beta 1,6(Gal beta 1,3)GalNAc as its major neutral oligosaccharide and also sialylated derivatives of the tetrasaccharide, including a monosialo derivative (Gal beta 1,4GlcNac beta 1,6(NeuAc alpha 2,3Gal beta 2,3)GalNAc and/or NeuAc alpha 2,3Gal beta 1,4GlcNAc beta 1,6 (Gal beta 1,3)GalNAc). These results suggest the possibility of carcinoma-associated alterations in O-linked oligosacchardes of cell surface sialomucins and in the activity of the beta 1,6-glucosaminyl transferase involved in mucin biosynthesis.

Antibodies, Monoclonal↗
PubMed1988

Biosynthesis of a tumor cell surface sialomucin. Maturation and effects of monensin.

The major cell surface glycoprotein (ascites sialoglycoprotein-1 (ASGP-1] of ascites 13762 rat mammary tumor cells is a large (Mr greater than 500,000), highly glycosylated sialomucin which is present in great abundance (greater than 0.5% of total cell protein). Thus, these tumors provide a useful system for investigating the biosynthesis of O-glycosylated glycoproteins. Previous studies in this system have demonstrated that initiation of O-linked oligosaccharides occurs throughout most of the transit period of ASGP-1 from the endoplasmic reticulum to the cell surface. By pulse-chase threonine labeling and precipitation with peanut agglutinin, ASGP-1 is first observed as an immature lightly glycosylated form (Mr approximately 200,000) which is converted to a more mature, more heavily glycosylated form (designated the premature or P form) with a half-time of about 30 min. The P form is then more gradually converted into the mature ASGP-1. Analysis of glucosamine-labeled oligosaccharitols obtained from the immature form showed primarily unsialylated derivatives consisting of the structures of the size of the tetrasaccharide Gal beta 1,4GlcNAc beta 1,6(Gal beta 1,3)GalNAc and smaller, whereas the mature form showed a mixture of sialylated and unsialylated structures. Desialylation of glucosamine-labeled mature form resulted in a glycoprotein intermediate in size between the immature and mature forms, indicating that the size change with maturation is not solely due to sialylation. Treatment of the cells with 10(-6) M monensin significantly reduced the conversion of immature to mature form without inhibiting initiation of O-linked oligosaccharides and without preventing sialylation. Analysis of oligosaccharitols obtained from ASGP-1 of monensin-treated cells showed that the major oligosaccharides are trisaccharide GlcNAc beta 1,6(Gal beta 1,3)GalNAc and sialylated trisaccharide GlcNAc beta 1,6(NeuAc alpha 2,3-Gal-beta 1,3) GalNAc. These results suggest that monensin specifically disrupts the compartment of the biosynthetic pathway which adds most of the beta 1,4-Gal to the oligosaccharides of ASGP-1 and that this compartment is separate from the primary site of sialylation.

Animals↗
PubMed1981

Extraction of light filth from tea: collaborative study.

The present AOAC method for determining insect and rodent filth in tea is time-consuming because it produced filter papers which are heavy in plant residue and therefore required long paper-reading times. A new method for the analysis of light filth in tea was developed to remedy existing problems and to improve recoveries. The method consists of the following steps: sample preparation, wet sieving, dilution with 40% isopropanol, flotation with mineral oil-heptane, and trapping off in a Wildman trap flask. In an interlaboratory collaborative study, analysts reported combined insect fragment recoveries of 99.2% for the proposed method and 93.0% for the AOAC method; the same analysts recorded combined rodent hair recoveries of 92.2% for the proposed method and 47.6% for the official method. Average times for reading individual subsamples were 9 min for the proposed method and 27 min for AOAC method. the proposed method has been adopted official first action.

Animals↗