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PubMed2004

Early blastomere determines embryo proliferation and caste fate in a polyembryonic wasp.

Polyembryonic development is a unique mode of metazoan development in which a single zygote generates multiple embryos by clonal proliferation. The polyembryonic parasitic insect Copidosoma floridanum shows one of the most extreme cases of polyembryony, producing up to 2,000 embryos from a single egg. In addition, this wasp exhibits an unusual polyphenism, producing two morphologically distinct larval castes, termed precocious and reproductive, that develop clonally from the same zygote. This form of development seems incompatible with a model of insect development in which maternal pre-patterning of the egg specifies embryonic axial polarity. Here we show that maternal pre-patterning in the form of germ plasm creates cellular asymmetry at the four-cell stage embryo of Copidosoma that is perpetuated throughout development. Laser ablations of cells show that the cell inheriting the germ plasm regulates both the fate and proliferation of the reproductive caste. Thus, we have uncovered a new mechanism of caste specification, mediated by the regulatory capacity of a single cell. This study shows that the evolution of mammalian-like regulative development of an insect embryo relies on a novel cellular context that might ultimately enhance developmental plasticity.

Amino Acid Sequence↗
PubMed2006

Energetics reveals physiologically distinct castes in a eusocial mammal.

Eusociality, which occurs among mammals only in two species of African mole-rat, is characterized by division of labour between morphologically distinct 'castes'. In Damaraland mole-rats (Cryptomys damarensis), colony labour is divided between 'infrequent worker' and 'frequent worker' castes. Frequent workers are active year-round and together perform more than 95% of the total work of the colony, whereas infrequent workers typically perform less than 5% of the total work. Anecdotal evidence suggests that infrequent workers may act as dispersers, with dispersal being limited to comparatively rare periods when the soil is softened by moisture. Here we show that infrequent workers and queens increase their daily energy expenditure after rainfall whereas frequent workers do not. Infrequent workers are also fatter than frequent workers. We suggest that infrequent workers constitute a physiologically distinct dispersing caste, the members of which, instead of contributing to the work of the colony and helping the queen to reproduce, build up their own body reserves in preparation for dispersal and reproduction when environmental conditions are suitable.

Animals↗
PubMed2005

An audit of study casts used to monitor tooth wear in general practice.

OBJECTIVE: To assess the outcome of compliance of advice sent to patients and dentists about monitoring tooth wear in general practice. METHOD: Postal questionnaires were sent to 70 patients and their dentists requesting information on the outcome of letters of advice sent to general dental practitioners regarding monitoring tooth wear with study casts. They also requested information about the reasons for the patients' referral, the outcome of treatment and whether study models had been taken. RESULTS: Replies were received from 60 dentists (87%) and 53 patients (75%). Of these, 16 patients and 16 dentists had moved from their recorded address. Study casts were reported as having been taken by 23 dentists (38%) and reported by 18 patients (34%). The most common reason for referral was advice about monitoring the wear and the appearance of their teeth. CONCLUSIONS: The compliance of the patients and dentists in monitoring tooth wear by using study casts in general practice was not successful. It raises issues regarding the value of consultant advice letters to this common clinical problem.

Adult↗
PubMed2005

Large area UV casting using diverse polyacrylates of microchannels separated by high aspect ratio microwalls.

Large area molding of long and deep microchannels separated by high aspect ratio microwalls is important for high sensitivity and high throughput microfluidic devices. Ultraviolet (UV) casting is a feasible, economical and convenient method of replication of such microstructures in plastics. It is shown that a wide variety of polyacrylates with diverse properties such as those made from epoxy (EP), polyurethane (UR), polyester (ES), poly (ethylene glycol) (EG) and poly(propylene glycol) (PG) can be used for the high aspect ratio (7-9) UV casting of such linear microstructures over a 100 mm diameter, enlarging the range of applications of the replicated microstructures. Some challenges arise. With the EG formulation, wavy microstructures were observed; this can be overcome by stress relaxation. With non-polar PG formulation, poor adhesion between the polyester substrate and resin can lead to delamination of the casting from the substrate during demolding; this can be overcome by pre-coating a partially cured same resin on the polyester substrate. An optimum UV irradiation time was important for cure at the deepest end of the microstructure without excessive crosslinking leading to much increased demolding forces. The viscosity and wetting capability of the formulations were found to affect replication fidelity.

Acrylates↗
PubMed1995

Stability of the palatal rugae as landmarks for analysis of dental casts.

The aims of this study were to determine if the palatal rugae are stable during normal growth, and whether treatment with either headgear or functional appliances affects the position of the rugae. Initial and 15-month recall dental casts of 94 patients enrolled in a study of early Class II treatment were evaluated. The children had been randomly assigned to one of three groups: control (n = 34), headgear (n = 30), and functional appliance (n = 30). Landmarks on the palatal raphe and palatal rugae were recorded using the Reflex Metrograph. A median palatal plane was constructed using the digitized raphe points as reference. Offsets from this plane to the ruga points and transverse and anteroposterior linear distances between ruga points were obtained for all casts. Transverse offsets and linear distances between medial points of the first rugae and the anteroposterior distances between the medial points of the second and third rugae did not show statistically significant changes in all groups. Significant changes were observed for the lateral points of the rugae, particularly in the headgear group. The medial rugae appear to be suitable anatomic points for the construction of stable reference planes for longitudinal cast analysis.

Analysis of Variance↗
PubMed2003

Three-dimensional analysis of dental casts based on a newly defined palatal reference plane.

The purpose of this study was to establish a new method for orthodontic diagnosis that integrates the three-dimensional (3-D) shape of a dental cast and the craniofacial morphology using a newly defined palatal reference plane. We also measured the accuracy of this new palatal reference plane as a reference for measurement and its spatial relationship to the framework of the craniofacial skeleton using lateral and frontal cephalometric radiography and maxillary dental casts, which were transferred using an anatomical face-bow. Eighteen female subjects were included in this study. The new reference plane in dental cast analysis corresponded to the A-PNS plane in the lateral view and to the J-J' plane in the frontal view, which have been shown to be sufficiently accurate as a reference for measurement. These results indicate that the application of this palatal reference plane, as a reference structure, should provide accurate and abundant 3-D data concerning malocclusion.

Cephalometry↗
PubMed1995

Identifying adult children of alcoholics: methodological review and a comparison of the CAST-6 with other methods.

Methods of identifying adult children of alcoholics are described and their psychometric properties are reviewed. These methods include self-report single questions and questionnaires and interview schedules. The CAST-6, a shortened version of the Children of Alcoholics Screening Test, is compared with a variety of these methods. The CAST-6 is confirmed as a useful brief screening measure. It was shown to be internally reliable, have good retest reliability and to agree well with other measures. Using a face to face interview as the comparison standard, however, a number of single questions performed equally as well as the CAST-6 and other more complex methods.

Adolescent↗
PubMed2001

Lipid analysis of follicular casts from cyanoacrylate strips as a new method for studying therapeutic effects of antiacne agents.

BACKGROUND: The cyanoacrylate follicular biopsy is an established method for the examination of the horny layer and quantitative assessment of microcomedones. We have optimized the method by separating follicular casts mechanically from the cyanoacrylate strips. OBJECTIVES: To use this method to analyse topical therapy-induced changes of the lipid composition in the sebaceous follicular infundibulum. METHODS: Both the follicular casts and the residual skin surface strip, the last representing a mixture of stratum corneum and surface lipids, were extracted twice with n-hexane-ethanol under ultrasonication, evaporated, redissolved in chloroform-methanol and separated by high-performance thin layer chromatography, using cholesterol sulphate, cerebroside, ceramide types 3 and 4, cholesterol, oleic acid, triolein, cholesterol oleate and squalene as standards. Identification was performed by computer-assisted densitometric analysis. Six patient groups receiving adapalene 0.1%, tretinoin 0.025%, clindamycin 1%, clindamycin 1% + tretinoin 0.025%, benzoyl peroxide 5% or benzoyl peroxide 5% + erythromycin 2% were investigated before and 12 weeks after application. RESULTS: A significant decrease in free fatty acid proportions combined with an increase in triglycerides was observed in the groups receiving antimicrobial therapy, supporting the hypothesis of lipolysis due to microbial colonization. The groups treated with topical retinoids showed an additional significant increase in ceramide subfractions, most probably reflecting their influence on epidermal keratinization. CONCLUSIONS: Our method proved suitable for the detection of quantitative and qualitative changes in lipid profiles of both infundibulum cast content and surface lipids. It enabled simple, non-invasive and objective assessment of the most relevant lipid classes in the sebaceous infundibulum, and efficient monitoring of drug effects on the follicular infundibulum.

Acne Vulgaris↗
PubMed1998

A comparative study of the tryptase release test and the cellular allergen stimulation test (CAST) in mite sensitive patients.

BACKGROUND: The stimulation of blood basophils to release mediators in vitro is widely used for diagnosis of allergic diseases. Tryptase release and sulphidopeptideleukotriene production are both triggered by cross-bridging of adjacent IgE molecules on the surface of IgE-bearing basophils. OBJECTIVE: We have compared the sensitivity of tryptase release test (TRT) and cellular allergen stimulation test (CAST) which, respectively, measure tryptase and sulphidopeptideleukotrienes that are produced upon cell stimulation by mite extracts. METHODS: Blood was taken from 247 patients with allergy to mites and 137 non-allergic control subjects. We measured tryptase release from basophils after allergen challenge in vitro by sandwich radioimmunoassay. The sulphidopeptideleukotrienes production was quantified by an ELISA test based on a monoclonal antibody which recognized leukotriene T4 (LTC4) and its metabolites LTD4 and LTE4. RESULTS: Our data show that both methods are equally effective to distinguish allergic patients from normal controls (P > 0.0001). There was a significant correlation between mite-specific serum IgE and CAST results (r = 0.69 for Dermatophagoides pteronyssinus; r = 0.73 for Dermatophagoides farinae). Correlations between IgE against mites and tryptase values appeared rather poor (r = 0.47 for Dermatophagoides pteronyssinus; 0.49 for Dermatophagoides farinae). Moreover, the data were used for the calculation of sensitivity, specificity, prevalence, and overall efficiency (Roc/Galen & Gambino analysis). The results were as follows: 71%, 87%, 64%, 76% (CAST results for Dermatophagoides farinae); 64%, 78%, 53%, 70% (TRT results for Dermatophagoides farinae). CONCLUSION: The partial discrepancies observed could be interpreted as a consequence of conditions that were technically not optimal. False-positive results may be due to the action of some non-specific cytotoxic agent, false-negative results may be due to hyporesponsive basophils or the low number of cells participating in the reaction and finally, in the case of TRT, to G4 monoclonal antibody to tryptase employed.

Adolescent↗
PubMed2001

High-resolution electron microscope observation of interface microstructure of a cast Al-Mg-Si-Bi-Pb(6262)/Al2O3p composite.

High-resolution electron microscopy was employed to characterize the interface structure of a cast Al-Mg-Si-Bi-Pb aluminium(6262)-based composite reinforced by alpha alumina particles with a trace of beta alumina in order to investigate the behaviour of alloying elements in cast composites. Except for a few primary Mg2Si particles, few reaction products were detected at the interface of Al/alpha-Al2O3 due to the unfavourable reaction kinetics during the squeeze-casting process. The Mg2Si particle has an orientation relationship with alpha-Al2O3 of [011]Mg2Si//[1210]alpha-Al2O3 (111)Mg2Si//(0006)alpha-Al2O3. A significant amount of MgAl2O4 was found on the surface of the beta-Al2O3 particles, which is in contrast to the small degree of reaction found on alpha-Al2O3 particles. MgAl2O4 and beta-Al2O3 particles have the following orientation relationship: [011]MgAl2O4//[1210]beta-Al2O3 (111) MgAl2O4//(0006)beta-Al2O3. The similar crystal structure of beta-Al2O3 to MgAl2O4 favours MgAl2O4 nucleation and growth on the surface of beta-Al2O3. Interfacial energy minimization dominates the atomic structure of the interface with the result that close packed planes and directions in the Al2O3 reinforcement and reaction products are parallel to the interfaces. Bi and Pb were found in the form of metallic nanometre particles between Al2O3 particles, or between the MgAl2O4 and Al2O3 particles, or in the open channels of beta-Al2O3 filled by the Al matrix.

Journal Article↗
PubMed2004

The origin of a 'true' worker caste in termites: mapping the real world on the phylogenetic tree.

The evolution of the 'true' worker caste in termites is not decisively inferred by coding and mapping both this character and the foraging behaviour on a phylogenetic tree. Answering to Thompson et al. (2000, 2003), and with reference to Grandcolas and D'Haese (2002), we show that this indecisive inference depends on the correct consideration paid to the outgroups. These last ones could be non subsocial cockroaches, or some wood-eating subsocial cockroaches often considered misleadingly as living ancestors, or even any hemimetabolous insects, all of them would be unambiguously lacking 'true' worker caste and pseudergate caste and not showing the 'one-piece' life type foraging behaviour. These statements derive from observing, coding and mapping the real world on the tree without making ad hoc assumptions. In that respect, because termites do not exist in isolation, apart from the tree of life, mapping the character of interest on the tree must be applied to the outgroups as well.

Animals↗
PubMed2003

Chimerical categories: caste, race, and genetics.

Is discrimination based on caste equivalent to racism? This paper explores the complex relationship between genetic, race and caste. It also discusses the debate over the exclusion of a discussion of caste-based discrimination at the 2001 World Conference against Racism, Racial Discrimination, Xenophobia and Related Intolerance held in Durban, South Africa.

Genetic Research↗
PubMed2002

Risk stratification applied to CAST registry data: combining 9 predictors. Cardiac Arrhythmia Suppression Trial.

Over 200,000 people in the United States die of sudden cardiac death (SCD) every year. Although many of these deaths occur in asymptomatic individuals, the vast majority of deaths occur in people who are under care for existing coronary heart disease. Implantable cardioverter/defibrillators (ICDs) have been shown in several randomized trials to be effective in prolonging lives of those at high risk for sudden cardiac death, but the criteria used in these trials and the ACC/AHA consensus guidelines would cover only a minority of patients. Developing methods to assign risk to individual patients without prior SCD events could promote the use of this life-saving therapy in those with especially high risk. Given sufficient physiologically relevant measurements from electrocardiogram analysis, clinical assessment, and demographic status, multivariate statistical methods for predicting survival can be used to combine many predictors of risk and calculate the risk for an individual patient. A survival analysis using Cox regression on data from the Cardiac Arrhythmia Suppression Trial (CAST) illustrates this concept. Patient age, sex, ejection fraction, smoking history, and prior myocardial infarction history, along with the frequency of premature beats and the presence of runs of ventricular tachycardia on Holter monitoring and the time from the index myocardial infarction to the baseline Holter and to recruitment into CAST were combined in a multivariate predictor derived from the Cox regression; this predictor significantly outperforms the individual predictors. A proposed test based on this predictor would identify as positive 7% of the CAST registry, with an average risk of death among the positives of 47%; 20% of those dead at 2 years would be positive. With improved component measurements, this approach has the potential for significantly improving risk stratification for the prevention of SCD.

Age Factors↗
PubMed2000

Accuracy of casts generated from dual-arch impressions.

STATEMENT OF PROBLEM: Dual-arch trays are often used to make simultaneous impressions of a prepared tooth and the opposing teeth. Many dentists are concerned with the accuracy of the casts generated from this type of impression. PURPOSE: The purpose of this investigation was to compare the accuracy of stone casts of a prepared tooth generated using 2 types of dual-arch impression tray/impression material combinations. MATERIAL AND METHODS: The maxillary left first molar on a dentoform mounted on an articulator was prepared for a full-coverage gold crown. Ten impressions were made with either a plastic (P) or metal (M) tray and a polyether (PE) or vinyl polysiloxane (VPS) impression material. Each impression was cast in improved dental stone, and the buccolingual dimension of the die was measured at the midpoint of the buccal and lingual gingival margins. The prepared tooth (T) served as the control. The data were analyzed using a 2-factor analysis of variance (ANOVA) alpha=.05. RESULTS: The P/VPS combination (10.673 mm) produced the largest die, followed by P/PE (10.602), T (10.508), M/PE (10.484), and M/VPS (10.472). The 2-factor ANOVA showed a significant difference between the tray types but not between the impression materials. CONCLUSION: The metal trays produced dies smaller than the tooth, and the plastic trays produced dies that were larger.

Dental Impression Materials↗
PubMed2001

Procedure for occlusal refinement of mounted definitive casts to reduce clinical time required for adjustment of occlusion.

The dental technician works with rigid casts and dies that do not tip or depress. The dentist must use fixed prostheses that have been fabricated in a laboratory setting in a clinical environment that is significantly different. Periodontal ligaments permit individual teeth to move within their boney housing. Mandibles tip and bend, but articulators cannot simulate all this activity. A relatively simple technique for adjusting inclines on the mounted definitive and opposing casts can compensate for many of the differences between rigid casts and subtle clinical tooth movement. This procedure can reduce required chairtime for adjusting the occlusion on crowns and fixed partial dentures.

Crowns↗
PubMed2002

The restoration of endodontically treated, single-rooted teeth with cast or direct posts and cores: a systematic review.

Direct post-and-core restorations with prefabricated posts are becoming increasingly popular. A literature review was conducted to compare the clinical and in vitro performance of cast posts and cores to that of direct cores with prefabricated posts in single-rooted teeth. Research on the restoration of endodontically treated teeth was identified through a search of electronic databases. The search yielded a total of 1773 references. After these references were subjected to strict inclusion criteria, 10 in vitro and 6 in vivo studies remained and critically reviewed. A comparison of fracture loads in the in vitro studies revealed no significant difference between cast and direct posts and cores. Meta-analysis of the data suggested that there is no difference in fracture behavior associated with the 2 treatment modalities. An overall survival analysis was not possible for the in vivo studies. The survival for cast posts and cores in 2 studies ranged from 87.2% to 88.1% and in a third study reached 86.4% for direct cores after 72 months. Randomized clinical trials on this topic were not available but should be conducted to verify published findings.

Dental Prosthesis Design↗
PubMed2004

The influence of cast shadows on visual search.

We show that cast shadows can have a significant influence on the speed of visual search. In particular, we find that search based on the shape of a region is affected when the region is darker than the background and corresponds to a shadow formed by lighting from above. Results support the proposal that an early-level system rapidly identifies regions as shadows and then discounts them, making their shapes more difficult to access. Several constraints used by this system are mapped out, including constraints on the luminance and texture of the shadow region, and on the nature of the item casting the shadow. Among other things, this system is found to distinguish between line elements (items containing only edges) and surface elements (items containing visible surfaces), with only the latter deemed capable of casting a shadow.

Contrast Sensitivity↗
PubMed2000

Morphological castes in a vertebrate.

Morphological specialization for a specific role has, until now, been assumed to be restricted to social invertebrates. Herein we show that complete physical dimorphism has evolved between reproductives and helpers in the eusocial naked mole-rat. Dimorphism is a consequence of the lumbar vertebrae lengthening after the onset of reproduction in females. This is the only known example of morphological castes in a vertebrate and is distinct from continuous size variation between breeders and helpers in other species of cooperatively breeding vertebrates. The evolution of castes in a mammal and insects represents a striking example of convergent evolution for enhanced fecundity in societies characterized by high reproductive skew. Similarities in the selective environment between naked mole-rats and eusocial insect species highlight the selective conditions under which queen/worker castes are predicted to evolve in animal societies.

Analysis of Variance↗