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At least 1,099 records · Page 61Linked to original sources
PubMed1983

The microvascular cast as a three-dimensional tissue skeleton: visualization of rapid morphological changes in tissues of the rat uterus.

A new interpretation of microvascular corrosion casting is described using examples from casts of the rat uterus taken during the oestrous cycle and early pregnancy. The casts are considered as representing a three-dimensional model of the tissue vascular space; this characteristic model or tissue skeleton is used to demonstrate transient morphological changes that may be difficult to visualize by other techniques, that may be obscured by other structures, or destroyed by conventional aldehyde fixation procedures. This new application, when supplemented by conventional histology to determine vessel distribution within the tissue and to confirm observations first made by casting, provides a technique for visualizing three-dimensional morphological changes in tissues that is accurate, relatively simple and far more rapid than the laborious method of histological serial sectioning and three-dimensional tissue reconstruction.

Animals↗
PubMedDate not supplied

Wing disc development during caste differentiation in the ant Pheidole megacephala (Hymenoptera: Formicidae).

The genus Pheidole has three distinct castes in females: queen, major, and minor workers. It has been believed that the larvae of major workers have prominent mesothoracic wing discs, although the minor worker larvae lack them. Here we conducted histological examinations of wing discs during larval development in P. megacephala. We show that all three castes have mesothoracic wing discs, at least in their early stage of the final larval instar, and that the wings degenerate differently in the dimorphic worker castes. The minute wing discs of minor workers neither grow nor metamorphose but disappear during the prepupal stage. On the contrary, the wing discs of major workers evaginate at the onset of the prepupal stage but subsequently degenerate by apoptotic cell death. This apoptotic wing degeneration in the prepupal stage was contradistinguished from wing degeneration in some lepidopteran insects, in which apoptosis occurs in the pupal wing buds. Our results suggest that each worker caste shows a different degeneration process to express the wingless character and that apoptotic degeneration has been adopted in association with the evolution of worker dimorphism.

Animals↗
PubMed1990

Hair casts: a clinical and electron microscopic study.

Hair casts were seen in 22 girls ranging in age from 4 to 13 years. They were localized to the frontal, vertex, and temporal areas. The number of affected hairs varied from one-tenth to one-third. Twenty of the 22 girls styled their hair in ponytails or pigtails. Compound root sheath casts were present in six of nine patients using 1% 4-dimethylaminocinamaldehyde stain. A mass of large polymorphous scales and solitary or clumped spores was seen on the surface of hair casts using scanning and transmission electron microscopy. Energy-dispersive x-ray microanalysis showed that elements of silicon, aluminum, and molybdenum were uniquely present in hair casts. We assume that tightly drawn braids, by causing local circulatory disturbances and inflammation of the scalp, may be one etiologic factor in the disorder.

Adolescent↗
PubMed2001

A new device to improve cast articulation procedures.

Achieving accurate cast articulation is a challenge for dentists and dental technicians. To ensure accuracy, a convenient, efficient, and predictable technique is needed to stabilize dental casts together, even when the casts are wet. The purpose of this article is to describe the use of a device specifically designed to secure casts together during the articulation process.

Adhesives↗
PubMed2005

Using silicone impression material and acrylic resin to fabricate remount casts for removable partial dentures.

A technique is described for fabrication of a remount cast for a removable partial denture. This procedure consists of filling the occlusal/incisal third with acrylic resin and injecting polyvinylsiloxane impression material into the irreversible hydrocolloid impression. This technique provides a simple method for making a remount cast and enables the clinician to remove and easily place the partial denture on the cast during occlusal refinement procedures without damage to the removable partial denture or the remount cast.

Acrylic Resins↗
PubMed1976

The influence of casting solvent composition on structure and permeability of acrylic-methacrylic ester copolymer films.

Decrease in the solvation of polymer by inclusion of ethanol in the acetone casting solution resulted in greater permeability to urea of cast acrylate-methacrylate film. The greater permeability was accompanied particularly by a decrease in pore size and increase in pore number, despite the absence of change in pore area. A decrease in cohesiveness in the film was suggested by the decrease in tortuosity of the pores as seen by scanning electron microscopy; also, water uptake was increased when the film was cast from an ethanolic solution. The results support the view that, in practice, the composition of the solvent, by its effect on microstructure, can affect the function of the film cast from it.

Acetone↗
PubMed1990

The effect of compliance on wall shear in casts of a human aortic bifurcation.

Rigid and compliant casts of a human aortic bifurcation were subjected to physiologically realistic pulsatile fluid flows. At a number of sites near the wall in the approximate median plane of the bifurcation of these models, fluid velocity was measured with a laser Doppler velocimeter, and wall motion (in the case of the compliant cast) was determined with a Reticon linescan camera. The velocity and wall motion data were combined to estimate the instantaneous shear rates at the cast wall. Analysis showed that at the outer walls the cast compliance reduced shear rates, while at the walls of the flow divider the shear rate was increased.

Aorta↗
PubMed1984

Effect of mild atherosclerosis on flow resistance in a coronary artery casting of man.

An in-vitro flow study was conducted in a mildly atherosclerotic main coronary artery casting of man using sugar-water solutions simulating blood viscosity. Steady flow results indicated substantial increases in pressure drop, and thus flow resistance at the same Reynolds number, above those for Poiseuille flow by 30 to 100 percent in the physiological Reynolds number range from about 100 to 400. Time-averaged pulsatile flow data showed additional 5 percent increases in flow resistance above the steady flow results. Both pulsatile and steady flow data from the casting were found to be nearly equal to those from a straight, axisymmetric model of the casting up to a Reynolds number of about 200, above which the flow resistance of the casting became gradually larger than the corresponding values from the axisymmetric model.

Arteriosclerosis↗
PubMed2006

Use of copper cast alloys to control Escherichia coli O157 cross-contamination during food processing.

The most notable method of infection from Escherichia coli O157 (E. coli O157) is through contaminated food products, usually ground beef. The objective of this study was to evaluate seven cast copper alloys (61 to 95% Cu) for their ability to reduce the viability of E. coli O157, mixed with or without ground beef juice, and to compare these results to those for stainless steel. E. coli O157 (NCTC 12900) (2 x 10(7) CFU) mixed with extracted beef juice (25%) was inoculated onto coupons of each copper cast alloy or stainless steel and incubated at either 22 degrees C or 4 degrees C for up to 6 h. E. coli O157 viability was determined by plate counts in addition to staining in situ with the respiratory indicator fluorochrome 5-cyano-2,3-ditolyl tetrazolium. Without beef extract, three alloys completely killed the inoculum during the 6-h exposure at 22 degrees C. At 4 degrees C, only the high-copper alloys (>85%) significantly reduced the numbers of O157. With beef juice, only one alloy (95% Cu) completely killed the inoculum at 22 degrees C. For stainless steel, no significant reduction in cell numbers occurred. At 4 degrees C, only alloys C83300 (93% Cu) and C87300 (95% Cu) significantly reduced the numbers of E. coli O157, with 1.5- and 5-log kills, respectively. Reducing the inoculum to 10(3) CFU resulted in a complete kill for all seven cast copper alloys in 20 min or less at 22 degrees C. These results clearly demonstrate the antimicrobial properties of cast copper alloys with regard to E. coli O157, and consequently these alloys have the potential to aid in food safety.

Alloys↗
PubMed1992

Use of casts in the necropsy diagnosis of fetal congenital heart disease.

OBJECTIVE: To evaluate a casting technique in the interpretation of fetal cardiac anatomy. DESIGN: In 32 fetuses, the echocardiographic and cast features were compared and correlated. PATIENTS: Three normal fetal heart specimens from spontaneous abortuses and 32 specimens from spontaneous or induced abortions with congenital heart malformation. RESULTS: There was close correlation between the echocardiographic and anatomical features in 32 abnormal fetuses studied. In some, additional features of diagnosis could be displayed on the cast and the relative sizes of the cardiac structures could be appreciated and defined. CONCLUSIONS: With increasing echocardiographic detection of congenital heart disease in early prenatal life, an increasing number of fetal heart specimens of small size are dissected for pathological confirmation. The use of silicone rubber casts to reproduce the internal anatomy proved a useful addition to dissection, providing a three dimensional model of the cardiac defect.

Autopsy↗
PubMed1995

Interaction of ischaemia and encainide/flecainide treatment: a proposed mechanism for the increased mortality in CAST I.

OBJECTIVE: To determine whether an interaction between encainide or flecainide and intercurrent ischaemia could account for the observed increase in cardiac and sudden deaths in the study group in the Cardiac Arrhythmia Suppression Trial (CAST) I. DESIGN: CAST I was a randomised, double blind, placebo controlled study in which patients received the drug which suppressed at least 6 premature ventricular contractions per minute by 80% or episodes of non-sustained ventricular tachycardia by 90%. Arrhythmic sudden death or aborted sudden death were the study end points. Measured secondary end points included recurrent myocardial infarction, new or increasing angina pectoris, congestive heart failure, and syncope. The CAST I database was analysed to determine which of three end points occurred first--cardiac death or cardiac arrest, angina pectoris, or non-fatal recurrent infarction. They were regarded as mutually exclusive end points. The triad of cardiac or sudden arrhythmic death plus congestive heart failure and syncope was similarly analysed. RESULTS: It was assumed that recurrent non-fatal infarction and new or increasing angina pectoris were ischaemic in origin. The sum of these non-fatal ischaemic end points and sudden death were nearly identical in the placebo group (N = 129) and the treatment group (N = 131). The one year event rate in each group was 21%. However, the treatment group had a much greater fatality rate (55 v 17; P < 0.0001) than the placebo group. The same relation was found when the data were examined on the basis of drug exposure rather than intention to treat. The temporal and circadian events were similar in each group and were consistent with an ischaemic pattern. No such patterns emerged from analysis of the presumed non-ischaemic end points of congestive heart failure and syncope. CONCLUSIONS: These data suggest that the interaction between active ischaemia and treatment with encainide or flecainide may have been responsible for the increased mortality seen in the treatment group in CAST I. This conversion of a non-fatal to a fatal event emphasises the need for future antiarrhythmic drugs to be screened in ischaemic models.

Angina Pectoris↗
PubMed1962

The nature of urinary casts.

The composition of hyaline casts has been investigated. The major constituent appears to be the urinary mucoprotein described by Tamm and Horsfall. Small amounts only of serum proteins are present. Neither the amounts excreted nor the concentration of Tamm-Horsfall protein appeared to determine the rate of cast formation. The only invariable association of hyaline cast formation was with the presence of significant amounts of serum proteins in the urine. In vitro it was found that aqueous solutions of serum albumin were particularly effective in producing precipitation of Tamm-Horsfall protein. This interaction was inhibited in normal urine but occurred to a greater extent in nephrotic urine and is suggested as the possible mechanism of hyaline cast formation.

Journal Article↗
PubMed1998

Reproductive caste determination in eusocial wasps (Hymenoptera: Vespidae).

Wasps (Vespidae) exhibit a range of social complexity, from solitary living to eusocial colonies, and thus are exemplary for studies of the evolutionary origin and maintenance of social behavior in animals. Integral to the definition of eusociality is the presence of reproductive castes, group members that differ qualitatively in their ability to reproduce in a social setting. Behavioral and morphological evidence suggests that caste determination, the developmental process by which differences in fecundity are established, occurs to a large extent before adult emergence (pre-imaginally) in many species of Vespidae, in both basal and advanced taxa within the clade (Vespinae+Polistinae), which includes most eusocial species. Pre-imaginal determination has been documented in many taxa (e.g. independent-founding Polistinae) where it was not thought to occur. Correlative and experimental studies indicate that differences in nutrition during larval development are often the basis of pre-imaginal caste determination. Pre-imaginal caste determination has important implications for the roles of subfertility and manipulation by nest mates in the evolution of eusocial behavior.

Journal Article↗
PubMed1985

A technique for quantitating airway size from bronchial casts.

To develop a technique for quantitating the size of airways at various positions in the bronchial tree, we analyzed casts of formalin-fixed excised lungs of five mature male ferrets. The left lower lobe of each cast was dissected, the diameter and position of each terminal bronchiole were entered into a computer programmed to reconstruct the airway system, and the cross-sectional areas of 120 conducting airways were measured. The fraction of the lobe served by each measured airway was estimated by dividing the sum of the squared diameters of the terminal bronchioles subtended by that airway by the summed squared diameters of all terminal bronchioles in the lobe. In each cast the relationship between an airway's cross-sectional area (Y) and the fraction of the lobe it was estimated to subtend (X) was described (0.91 less than R2 less than 0.95) by the expression ln(Y) = A + B ln(X) + C [ln(X)]2. Linear regression of ln(Y) on ln(X) for 30-50 airways estimated to serve fractions of the lobe around each of three arbitrarily selected levels (airways serving 0.7, 2.2, and 9.5% of the lobe) was adequate to characterize the area of airways at each level in each of the five animals with 95% confidence intervals narrower than 8% of the estimated area. Variability of airway size at each level among the five casts was modest, suggesting that this technique identified analagous airways in the various animals. Interindividual variability did not increase when the data were reanalyzed with terminal units defined on the basis of airway diameters rather than on the morphological identification of terminal bronchioles.

Animals↗
PubMed1990

Reversible impairment of forearm vasodilation after forearm casting.

To examine whether the resumption of normal physical activity after forearm immobilization would reverse impaired vasodilation, the minimal vascular resistance was examined in six subjects who had forearm casts placed for broken forearm bones. Each subject was examined twice, once within 48 h after forearm cast removal and again approximately 29 days later. The formerly casted forearm and the opposite forearm (noncasted) were examined. Minimal vascular resistance decreased in the casted forearm from 3.0 +/- 0.4 to 2.6 +/- 0.5 mmHg.ml-1.min.100 ml (P less than 0.014). There was no change in the noncasted forearm: 2.5 +/- 0.3 vs. 2.5 +/- 0.3 mmHg.ml-1.min.100 ml. This study shows that maximal vasodilation improves with the resumption of normal physical activity and therefore demonstrates that immobilization is associated with a reduced forearm vasodilator capacity.

Adult↗
PubMed2003

Surface area of the human vagina as measured from vinyl polysiloxane casts.

Sixty-two vinyl polysiloxane casts from subjects in the lying, supine position were measured for surface area with five shapes: conical, parallel sides, heart, slug, and pumpkin seed being included. The surface areas ranged from 65.73 to 107.07 cm(2) with a mean of 87.46 cm(2) and a standard deviation of 7.80 cm(2). There were no significant differences in surface area among the shape groups. And no correlations with surface area were found by parity or by rod length, introital diameter, posterior length of casts as measured with string, or greatest width and greatest depth of casts. 70% of the casts had a surface area of 84.50 cm(2) or above, and 90% had a surface area of 77.72 cm(2) or above. Variation within the interquartile range (75th to 25th percentile) was +/-5.2% of the median.

Black People↗
PubMed1978

Gene differentiation among the Dhangar caste-cluster of Maharashtra, India.

Genetic differentiation among the 22 Dhangar castes of Maharashtra, India, is studied using data on several polymorphic serological and biochemical loci employing Nei's distance measures. The intercaste genetic distances and the coefficient of gene diversity among these caste groups are found to be rather small. The relationship between gene identity and geographic distance is also studied empirically from the gene frequency data. All these analyses indicate that genetic differentiation among the Dhangar castes is at its very early stage only. It is also suggested that these caste groups probably originated from a common stock and are in the process of differentiation by fission with very little intercaste migration in the recent past.

Demography↗
PubMed1985

A sero-biochemical genetic study of Jalari and Brahmin caste populations of Andhra Pradesh, India.

Blood specimens from Jalari and Brahmin caste populations of Andhra Pradesh, India, were examined for blood groups, red cell enzymes, and serum proteins. Of 33 genetic loci studied, 16 were observed to be invariant among both the castes, while common polymorphism or rare variants were observed in one or both populations for the other loci. Three rare heterozygotes at the phosphoglucoisomerase locus, two different peptidase A variants occurring once each and single cases of rare 6-phosphogluconate dehydrogenase and transferrin variants were recorded. Also a few cases of hemoglobin AS and anhaptoglobinemia were observed. The difference in rare variants between the two castes is conspicuous but large differences in their gene frequencies at the polymorphic loci were not observed. It is pointed out that the frequency of rare variants in the tribal and caste populations of Southern India appears to be higher than observed in temperate-dwelling civilized populations.

Adolescent↗