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PubMed1985

Different relations between infarct size and occluded bed size in barbiturate-anesthetized versus conscious dogs.

The relation between infarct size and occluded bed size in barbiturate-anesthetized (n = 32) and conscious (n = 34) dogs was compared using models of the left anterior descending (n = 43) and circumflex (n = 23) coronary arteries with 2 day old infarcts. Infarct and occluded bed (postmortem coronary arteriography) masses were measured by computerized planimetry of weighed left ventricular rings. For either type of occlusion, infarcts were larger in anesthetized than in conscious dogs (56 versus 33% occluded bed, p less than 0.001), with greater slopes of the linear regressions between infarct size and occluded bed size (p less than 0.001) and less epicardial sparing (p less than 0.05) on topographic mapping. Although arterial and left atrial pressures were similar in the two groups, heart rates were higher in the anesthetized dogs, both before (127 versus 88 beats/min, p less than 0.001) and after (151 versus 109 beats/min, p less than 0.001) occlusion. Myocardial blood flow distribution (radioactive microspheres, n = 33) favored the epicardium in anesthetized dogs, with lower endocardial-epicardial flow ratios pre- and postocclusion. Also, the level of total plasma catecholamines (radioenzymatic assay) was higher in barbiturate-anesthetized (n = 5) than in conscious (n = 5) dogs. Increasing the heart rate in conscious dogs (n = 18) to that of the anesthetized group (139 beats/min) by pacing produced larger infarcts and greater linear regression slopes, as seen in anesthetized dogs. Decreasing the heart rate in anesthetized dogs (n = 7) to that of the conscious group (98 beats/min) by sinoatrial node destruction and pacing resulted in smaller infarcts and lower linear regression slope, as seen in conscious dogs. Thus, the larger infarcts in barbiturate-anesthetized dogs appeared to be related mainly to the tachycardia, although transmural maldistribution of flow and increased circulating catecholamines might have contributed.

Analysis of Variance↗
PubMed1998

Measurement and Calculation of Three-Dimensional Grain Sizes and Size Distribution Functions.

: Three-dimensional (3D) grain sizes and size distribution functions (SDFs) are generally obtained by converting the 2D or 1D grain sizes to 3D with the methods based on a spherical grain shape model (S-model), which can produce large systematic errors. In this report, a new polyhedral grain model (P-model) is developed and experimentally checked with the directly measured 3D grain sizes. The results show that the systematic error originating from the S-model can be corrected by using the new polyhedral grain model.

Journal Article↗
PubMed1996

Analytical properties and sensor size effects of a micrometer-sized optical fiber glucose biosensor.

A micrometer-sized fiber-optic fluorescence biosensor for glucose has been fabricated. The sensor is 100 times smaller than existing glucose optodes. It is based on the enzymatic reaction of glucose oxidase that catalyzes the oxidation of glucose to gluconic acid and hydrogen peroxide while consuming oxygen. Tris(1,10-phenanthroline)ruthenium chloride, an oxygen indicator, is used as a transducer. The ruthenium complex and glucose oxidase are incorporated into acrylamide polymer that is attached covalently to a silanized optical fiber tip surface by photocontrolled polymerization. A study of the dependence of the fluorescence intensity on sensor size shows that, under normal operating conditions, the signal decreases with the sensor diameter rather than its volume. Also, the response of micrometer-sized sensors is improved by about 20% compared to that of larger fiber-optic glucose sensors. Due to its small size and the lack of membrane support, the response time of the sensor is only 2 s. An absolute detection limit of around 1 x 10(-15) mol is achieved. The new glucose sensor is at least 25 times faster and its absolute sensitivity 5-6 orders of magnitude higher than that of current glucose optodes.

Biosensing Techniques↗
PubMed2002

Substrate size selectivity of 20S proteasomes: analysis with variable-sized synthetic substrates.

Proteasomes are tubular complexes with proteolytic activities on their lumenal surfaces so that large substrates should be sterically hindered from reaching the catalytic sites. Here we examine effects of substrate size on rates of cleavage by 20S proteasomes of Methanosarcina thermophila. Synthetic chromogenic substrates of variable size were prepared by linking a constant substrate group (Ala-Ala-Phe-p-nitroanilide) to a linear polymer (methoxypolyethylene glycol) with variable chain length. The smallest macromolecular substrates were cleaved more efficiently than free tripeptide substrate, and cleavage of macromolecular substrates was saturable, whereas cleavage of free tripeptide substrate was not, indicating mechanistic differences between the cleavage of large and small substrates. Rates of macromolecular substrate cleavage decreased progressively up to 10-fold as the size of the polymeric component of substrates increased. Macromolecular synthetic substrates appear to be better models of proteasome action on natural protein substrates and demonstrate substrate size selectivity of proteasomes.

Amino Acid Sequence↗
PubMed1991

Relationship of cardiac size to maximal oxygen uptake and body size in men and women.

It has been suggested in previous studies that the difference in endurance performance between males and females is related to gender-specific differences in cardiac function. Other studies have not equated males and females for physical condition, and this may have contributed to the findings. The purpose of this study was to determine the extent to which the difference in VO2max in groups of similarly trained males and females was explained by gender differences in cardiac size, fat-free weight (FFW) and hemoglobin concentration [( Hb]). Measurements of VO2max, FFW, [Hb] and cardiac size (LVM) were made on 19 males and 20 females comparable in age and cardiorespiratory capacity. The difference between men and women in LVM accounted for 68.3% of the gender difference in VO2max, and the combination of LVM and FFW accounted for 98.7% of the gender-related difference in VO2max. It was concluded that the gender difference in LVM accounts for a majority of the difference in VO2max in males and females, with other aspects of body size accounting for nearly all the remaining difference. The gender difference in heart size primarily reflects the smaller overall dimensions of women.

Body Constitution↗
PubMed1984

Body size and food size in freshwater zooplankton.

We used double-label liquid scintillation techniques to measure the efficiencies with which eight different-sized zooplankton species ingested four cell types relative to a standard cell type (Chlamydomonas). Efficiency ratios (ERs: clearance rate on cell type X / clearance rate on Chlamydomonas) on the three ultraplankton (<5 mum in diameter) cells (a coccoid bacterium and the algae Synechococcus and Nannochloris) varied greatly among zooplankton species but were not correlated with zooplankton body length. Variation in ERs on a much larger (17 x 14 mum) algal cell (Cryptomonas) was only partly explained by zooplankton body length. The eight zooplankton species were classified into three functional groups: (i) species having moderate to high ERs on all ultraplankton (0.4 < ER < 1.6) and ERs on Cryptomonas proportional to their body lengths (Conochilus, Diaphanosoma, and probably Keratella cochlearis and Ceriodaphnia); (ii) species having extremely low ERs on bacteria (mean ER < 0.05), higher but still low ERs on ultraphytoplankton (ER generally < 0.4), and ERs on Cryptomonas proportional to their body lengths (Bosmina, Diaptomus copepodites and adults); (iii) species having extremely low ERs on all ultraplankton (mean ER < 0.05) and ERs on Cryptomonas much higher than expected given their body lengths (Keratella crassa, Polyarthra, and Diaptomus nauplii). These functional groups follow neither taxonomic nor body-length groupings. We conclude that zooplankton body length may influence the maximal particle size a species can ingest but has little influence on the ingestion of smaller particles. Two frequently used models relating zooplankton body size and food size are unrealistic.

Journal Article↗
PubMed1986

Exon/intron organization of the chicken type II procollagen gene: intron size distribution suggests a minimal intron size.

Overlapping genomic clones have been isolated that contain the alpha chain and COOH-terminal propeptide coding regions of the chicken type II procollagen gene. All type II procollagen exon sequences present in these clones have been identified and mapped by DNA sequencing. These include 43 exons coding for the alpha-chain triple helix, 1 exon coding for the junction between the COOH-terminal propeptide and the alpha-chain region, and 3 exons coding for the COOH-terminal propeptide and 3' noncoding sequences. With the exception of one additional intron between 2 exons coding for amino acids 568-585 and 586-603, exon-intron boundaries have been conserved when compared with genes for all other characterized genes for fibrillar collagens. The chicken type II procollagen gene differs from most other collagen genes in having introns of considerably smaller average size. The size distribution of the introns suggests that approximately equal to 80 base pairs may be a minimal functional size for introns in this gene. This size of intron may be necessary in a gene with a very large number of small exons to prevent aberrant splicing from removing exon sequence together with intron sequence.

Animals↗
PubMed1990

An analysis of hospital union election activity: 1985-1987--by hospital ownership, size, and system, and employee organization and bargaining-unit size.

During the three-year period 1985-1987, there were 238 elections in nongovernmental, short-term hospitals to determine whether or not unions would represent the employees. Unions had a success rate of 47.1 percent, similar to that of earlier years. This study reports these election results by hospital and election characteristics. For hospitals, the analysis includes elections by census region, ownership, bed size, and multi-institutional characteristics. For elections, the analysis includes the nature and type of election, employee organization, and employee bargaining-unit-size characteristics. This study concludes that the number of union elections decline as hospital bed size increases, and the union success rate is curvilinear and higher in both small and very large hospitals; union success declines as bargaining-unit size increases. Investor-owned and nonprofit, religious hospitals that are members of multi-institutional systems have lower union success rates than nonsystem hospitals do in their ownership category. However, unions are much more successful in multi-union and decertification elections compared with single-unit elections and initial recognition elections.

Data Collection↗
PubMed2001

Histological assessment of colorectal adenomas by size. Are polyps less than 10 mm in size clinically important?

OBJECTIVE: To define the relative risk of malignant transformation in colorectal adenomas less than 10 mm in diameter. DESIGN: Prospective study. SETTING: District general hospital, UK. SUBJECTS AND MATERIALS: 1228 polyps detected endoscopically in 445 patients over the 10-year period 1989-1999. MAIN OUTCOME MEASURES: Site, size, histological type and dysplastic grade of polyp. RESULTS: 657 of the 1228 polyps were adenomas: 281 (43%) tubular, 339 (51%) tubulovillous and 37 (6%) villous. In the 357 adenomas less than 10 mm in diameter, 11 (3%) were severely dysplastic and 2 carcinomas were detected, though neither was less than 5 mm in size. The relative risk of malignancy or severe dysplasia in adenomas of 10 mm or more compared with those of less than 10 mm was 3.8 (p < 0.0001). CONCLUSIONS: Although severe dysplasia and malignancy do occur in adenomas less than 10 mm in size, they are rare in lesions of less than 5 mm. We recommend routine destruction of all polyps 5 mm or more in size, though it is not essential to remove those of less than 5 mm if they are kept under surveillance.

Adenoma↗
PubMed2001

Tracking of body size from birth to late adolescence: contributions of birth length, birth weight, duration of gestation, parents' body size, and twinship.

Birth weight has correlated positively with adult body mass index (BMI), but rarely have birth length, duration of gestation, or parents' body size been taken into account. The authors examined tracking of birth length and weight, adjusted for gestational age, to late adolescence, with special reference to parents' height and BMI. Longitudinal information from a nationally representative sample of Finnish twin adolescents (birth cohorts 1975-1979) and their parents was collected via questionnaires mailed when the twins were aged 16 years (n = 4,376; 2,062 males, 2,314 females) and 18 years (n = 3,917; 1,742 males, 2,175 females). The twins showed significant tracking of body size from birth to late adolescence, which was greatly influenced by their parents' body size. Height in adolescence was predicted by length and weight at birth and by parents' height, whereas BMI was predicted by birth weight and parents' BMI. An especially high risk for overweight was found for subjects of average length but a high weight at birth. These findings suggest that the intrauterine period has enduring effects on later body size but leave unresolved whether these effects are genetic or environmental.

Adolescent↗
PubMed2002

Genetic effective size is three orders of magnitude smaller than adult census size in an abundant, Estuarine-dependent marine fish (Sciaenops ocellatus).

Using eight microsatellite loci and a variety of analytical methods, we estimated genetic effective size (N(e)) of an abundant and long-lived marine fish species, the red drum (Sciaenops ocellatus), in the northern Gulf of Mexico (Gulf). The ratio N(e)/N, where short-term variance N(e) was estimated via the temporal method from shifts in allele-frequency data over four cohorts and where N reflected a current estimate of adult census size in the northern Gulf, was approximately 0.001. In an idealized population, this ratio should approximate unity. The extraordinarily low value of N(e)/N appears to arise from high variance in individual reproductive success and perhaps more importantly from variance in productivity of critical spawning and nursery habitats located in spatially discrete bays and estuaries throughout the northern Gulf. An estimate of N(e) based on a coalescent approach, which measures long-term, inbreeding effective size, was four orders of magnitude lower than the estimate of current census size, suggesting that factors presently driving N(e)/N to low values among red drum in the northern Gulf may have operated similarly in the past. Models that predict N(e)/N exclusively from demographic and life-history features will seriously overestimate N(e) if variance in reproductive success and variance in productivity among spatially discrete demes is underestimated. Our results indicate that these variances, especially variance in productivity among demes, must be large for red drum. Moreover, our study indicates that vertebrate populations with enormous adult census numbers may still be at risk relative to decline and extinction from genetic factors.

Animals↗
PubMed2000

Maternal genotype influences pea seed size by controlling both mitotic activity during early embryogenesis and final endoreduplication level/cotyledon cell size in mature seed.

When reciprocal crosses are made between different pea genotypes, there is a strong maternal influence on mature seed size of the reciprocal hybrids, i.e. their dry weights are similar to that of seeds obtained from their maternal parents. Reciprocal crosses between pea varieties having very different mature seed sizes were used to investigate how the maternal genotype controls seed development and mature seed size. The differences in dry seed weight between genotypes and reciprocal hybrids reflected differences in both cotyledon cell number and mean cell volume, and the maternal control on the establishment of these two traits was investigated. Using flow cytometry, data relative to endoreduplication kinetics in cotyledons during the transition between the cell division phase and maturation were obtained. The appearance of nuclei having an 8C DNA content indicates the initiation of the endoreduplication phenomenon and thus the end of the cell division phase. It was shown that the duration of the cell division phase was the same in the reciprocal hybrids, its value being intermediate between those recorded for their maternal parents. This result indicates that the timing of development of the embryo is not under maternal control, but depends on its own genotype. Consequently, maternal genotype must influence the mitotic rate during the cell division phase to achieve differences in cell number found in the cotyledons of mature F1-reciprocal hybrids. The final level of endoreduplication in cotyledons of mature seeds was also investigated. This study showed that there is a close relationship (r2 = 0.919) between the endoreduplication level in mature cotyledons and seed dry weight or mean volume of cotyledon cells, suggesting that both maternal and non-maternal factors could control the number of endoreduplicating cycles in the cotyledons and, hypothetically, the cotyledon cell size.

Genotype↗
PubMed1998

A new method for determining bra size and predicting postaugmentation breast size.

The current popular system of determining bra size is inaccurate so often as to be useless. Add to this the many different styles of bras and the lack of standardization between brands, and one can see why finding a comfortable, well-fitting bra is more a matter of educated guesswork, trial, and error than of precise measurements. An improved method of determining cup size by directly measuring the circumference of the breast is presented in this paper. If adopted commercially, this simple method could reduce dramatically the number of women said to be wearing the "wrong-sized bra." The technique has also been found to be an accurate predictor of postoperative breast size in augmentation and reduction surgery, and thus offers plastic surgeons an opportunity to better meet the expectations of women undergoing these procedures.

Adult↗
PubMed2000

Size reduction of small bowels from adult cadaveric donors to alleviate the scarcity of pediatric size-matched organs: an anatomical and feasibility study.

BACKGROUND: Small bowel transplantation in children weighing less than 10 kg is hindered by the lack of size-matched donors. The ability to create reduced size small bowel grafts from adult cadaveric donors suitable for use in young children has been studied. METHODS: Volumetric assessment of computed tomography scans were used to evaluate abdominal cavity and small bowel volumes in children. Small bowels were retrieved from adult cadaveric donors and reduced in size. RESULTS: Computed tomography studies of the abdominal cavity showed that the mean volume available for a small bowel graft was 260 ml in children less than 5 kg (n = 5) and 460 ml in children weighing 5-10 kg (n = 5). Fifteen small bowels were successfully reduced to provide an ileal graft of one meter while keeping the whole length of the superior mesenteric artery and vein after their dissection in the proximal part of the mesentery. The mean volume of the grafts created was 270 ml in seven thin patients (body mass index [BMI] <25), 390 ml in five preobese patients (25< BMI<30), and 490 ml in three obese patients (BMI>30). Mesenteric transillumination in thin donors allowed safe dissection and complete hemostasis. No diameter reduction was required. Technical modifications permitted the creation of two grafts, one ileal and the other jejunal from a single donor. Volumetric and surgical data show that implantation of up to two meters of ileum from a thin adult weighing up to 80 kg is feasible in children weighing less than 10 kg. CONCLUSION: Size reduction of adult cadaveric small bowels can provide suitable grafts for children of less than 10 kg and could expand the potential pool of donors for these patients.

Adult↗
PubMed2002

Egg-size evolution in aquatic environments: does oxygen availability constrain size?

Selection against large eggs has been proposed for aquatic environments, putatively because large eggs should have more difficulty obtaining the required oxygen. Here, we use brown trout (Salmo trutta) eggs to provide an experimental test of this hypothesis. At high levels of dissolved oxygen (14 mg l(-1)), egg survival was high and independent of egg size. At low oxygen levels (2.3 mg l(-1)), survival decreased overall, and was higher for large-egged than small-egged siblings. Thus, contrary to conventional expectation, low oxygen levels selected for large rather than small eggs. A second experiment using Atlantic salmon (S. salar) eggs indicated that oxygen consumption increases relatively slowly with increasing egg mass (allometric constant = 0.44). The failure of the conventional 'bigger is worse during incubation' hypothesis may thus be due to the erroneous assumption that oxygen consumption increases at a greater rate with increasing egg mass than does the egg surface area that is available for oxygen diffusion. We also demonstrate, using data from Atlantic salmon, that nest-specific oxygen consumption decreases with increasing egg size, but that this effect is more pronounced for large than for small females. This may help to explain the positive correlation between adult body size and egg size observed in fishes that cluster their eggs.

Animals↗
PubMed2006

When does size not matter? Effects of stimulus size on affective modulation.

Motivationally relevant stimuli have been shown to receive prioritized processing compared to neutral stimuli at distinct processing stages. This effect has been related to the evolutionary importance of rapidly detecting dangers and potential rewards and has been shown to be modulated by the distance between an organism and a faced stimulus. Similarly, recent studies showed degrees of emotional modulation of autonomic responses and subjective arousal ratings depending on stimulus size. In the present study, affective modulation of pictures presented in different sizes was investigated by measuring event-related potentials during a two-choice categorization task. Results showed significant emotional modulation across all sizes at both earlier and later stages of processing. Moreover, affective modulation of earlier processes was reduced in smaller compared to larger sizes, whereas no changes in affective modulation were observed at later stages.

Adult↗
PubMed2004

Myocardial SPECT perfusion defect size compared to infarct size by delayed gadolinium-enhanced magnetic resonance imaging in patients with acute or chronic infarction.

BACKGROUND: Single photon emission computed tomography (SPECT) perfusion imaging has been considered a reference method for non-invasive estimation of infarct size in man. Recently, delayed gadolinium-enhanced magnetic resonance imaging (DE-MRI) has evolved as an accurate tool to quantify infarct size. Therefore, the present study was designed to compare perfusion defect size by SPECT to hyperenhanced volume by DE-MRI. METHODS: DE-MRI was performed in 30 patients. Fourteen were patients with revascularized first-time acute infarctions, eight revascularized chronic infarctions, and eight clinically referred non-revascularized patients. SPECT was performed in the same patients and analysed by a commercial package. RESULTS: The hypoperfused volume by SPECT was larger than the hyperenhanced volume by DE-MRI by 8 +/- 8 ml (6% +/- 5 percentage points), 10 +/- 18 ml (6% +/- 11 percentage points), and 26 +/- 30 ml (12% +/- 10 percentage points) in the acute, chronic and clinical populations, respectively. Left ventricle wall volume was smaller by SPECT in all settings. CONCLUSION: The SPECT perfusion defect size was comparable with but generally slightly larger than the hyperenhanced volume by DE-MRI in both absolute and relative terms in patients with acute and chronic infarction. The results may be related to systematic differences between modalities but could also be influenced by biological phenomena such as wall thinning or hypoperfused but viable myocardium.

Acute Disease↗
PubMed1980

The size of hydroxyl groups in solution and the changes in size associated with the ionization of phenolic, carboxylic and amino groups in phenolic quaternary ammonium salts, nicotine and some amino acids: possible implications for drug-water and drug-receptor interactions.

Size in solution can be expressed either as the apparent molal volume at infinite dilution (phi 0v) amd the concentration parameter (j) or as the partial molal volume of the solute at infinite dilution (V0(2)) and the concentration parameter for the solute or solvent (qs or qw). Although calculated differently, these are derived from the same results and are equivalent. From measurement with phenolic quaternary ammonium salts, including compounds with high nicotine-like activity, the apparent size of the hydroxyl group in water is small and variable. Phenolic groups are slightly larger than alcoholic groups, which should be better hydrogen donors. By measuring the volume change associated with ionisation it is possible to measure the size of charged groups such as phenate and carboxylate; these are much smaller than phenolic and carboxyl. Ammonium groups, however, are only slightly smaller than the corresponding amines. The zwitterion forms of amino acids are associated with a minimum in volume but the volume changes increase with chain length from glycine to gamma-aminobutyric acid. Groups separated by less than this distance interact in their effects on water. Decreases in volume or unexpectedly small increments in apparent molal volume represent decreases in entropy which must be taken into account in drug-water-receptor interactions. Although they may be offset by enthalpy changes, they should favour binding because there is more scope for an increase in entropy. This might explain the association of the small apparent size in water of the hydroxyl group in many compounds with its effects of their affinity for receptors.

Amines↗