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PubMed2004

Caste determination in a polyembryonic wasp involves inheritance of germ cells.

Social insects are characterized by the development of castes in which some colony members reproduce whereas others function as altruistic helpers. The conditional switch controlling caste formation usually involves environmental stimuli that act on processes that regulate development of individuals. Unlike other social species, embryos of polyembryonic wasps develop clonally to produce large numbers of genetically identical offspring and two morphologically distinct castes. All embryos in a clone exist in an identical environment, the host, yet develop into either reproductive larvae that mature into adult wasps or soldier larvae whose function is defense. Here, we report that caste determination in Copidosoma floridanum involves inheritance of germ cells. Expression of a C. floridanum homolog (Cf-vas) of the germ cell marker Vasa indicated that the B(4) blastomere in four cell-stage embryos is specified as a primordial germ cell. Vas expression later in development further indicated that embryos developing into reproductive larvae possess primordial germ cells whereas embryos developing into soldier larvae do not. Ablation of the B(4) blastomere resulted in most broods containing only soldiers whereas ablation of other blastomeres produced broods containing both castes. These results indicate that soldier larvae are obligately sterile and reveal a previously unknown role for germ cells in caste formation.

Amino Acid Sequence↗
PubMed2001

Imaging of experimental end-to-side anastomoses in a cast model.

OBJECTIVE: To evaluate cast models in the imaging of experimental end-to-side anastomoses. DESIGN: Experimental study. SETTING: Teaching hospital, Finland. INTERVENTIONS: 20 non-stenosed and 10 stenosed end-to-side anastomoses were constructed using a Dacron prosthesis 8 mm in diameter. Cast models were made of all anastomoses, and anteroposterior and oblique projection radiographs were taken of them. Cross-sectional radiographs were also taken of the stenosed anastomoses. MAIN OUTCOME MEASUREMENTS: The diameters and areas of anastomoses were measured on the radiographs and compared with the corresponding measurements of the casts. RESULTS: No filling defects were observed in any of the cast models and only minor differences were found between the corresponding measurements of the anteroposterior and oblique projection radiographs and casts. The lower density of the contrast medium in the stenotic anastomoses indicated a stenosis. In the cross-sectional radiographs of the stenotic anastomoses there was a significant reduction (p < 0.001) both in the diameter and the area, the mean of which was 63% and the median 61%. CONCLUSIONS: Radiographs of cast models look promising in imaging of experimental end-to-side anastomoses when cross-sectional projections are also used.

Anastomosis, Surgical↗
PubMed1992

Silica exposure in hand grinding steel castings.

Exposure to silica dust was studied in the grinding of castings in a steel foundry that used conventional personal sampling methods and new real-time sampling techniques developed for the identification of high-exposure tasks and tools. Approximately one-third of the personal samples exceeded the National Institute for Occupational Safety and Health recommended exposure limit for crystalline silica, a fraction similar to that identified in other studies of casting cleaning. Of five tools used to clean the castings, the tools with the largest wheels, a 6-in. grinder and a 4-in. cutoff wheel, were shown to be the major sources of dust exposure. Existing dust control consisted of the use of downdraft grinding benches. The size of the casting precluded working at a distance close enough to the grates of the downdraft benches for efficient capture of the grinding dust. In addition, measurements of air recirculated from the downdraft benches indicated that less than one-half of the respirable particles were removed from the contaminated airstream. Previous studies have shown that silica exposures in the cleaning of castings can be reduced or eliminated through the use of mold coatings, which minimize sand burn-in on the casting surface; by application of high-velocity, low-volume exhaust hoods; and by the use of a nonsilica molding aggregate such as olivine. This study concluded that all these methods would be appropriate control options.

Air Pollutants, Occupational↗
PubMed2002

Cast: a novel protein of the cytomatrix at the active zone of synapses that forms a ternary complex with RIM1 and munc13-1.

The cytomatrix at the active zone (CAZ) has been implicated in defining the site of Ca2+-dependent exocytosis of neurotransmitter. We have identified here a novel CAZ protein of approximately 120 kD from rat brain and named it CAST (CAZ-associated structural protein). CAST had no transmembrane segment, but had four coiled-coil domains and a putative COOH-terminal consensus motif for binding to PDZ domains. CAST was localized at the CAZ of conventional synapses of mouse brain. CAST bound directly RIM1 and indirectly Munc13-1, presumably through RIM1, forming a ternary complex. RIM1 and Munc13-1 are CAZ proteins implicated in Ca2+-dependent exocytosis of neurotansmitters. Bassoon, another CAZ protein, was also associated with this ternary complex. These results suggest that a network of protein-protein interactions among the CAZ proteins exists at the CAZ. At the early stages of synapse formation, CAST was expressed and partly colocalized with bassoon in the axon shaft and the growth cone. The vesicles immunoisolated by antibassoon antibody-coupled beads contained not only bassoon but also CAST and RIM1. These results suggest that these CAZ proteins are at least partly transported on the same vesicles during synapse formation.

Aging↗
PubMed1993

Biometric analysis of the dental casts of Maasai following traditional extraction of mandibular permanent central incisors and of Kikuyu children.

Dental plaster casts of 93 Maasai and 79 Kikuyu children age 12-15 years were analysed. Four biometric measurements were taken of the maxillary and mandibular casts: intercanine distance (C-C), inter-molar distance (M-M), canine arch circumference (C-C ACirc.), and molar arch circumference (M-M ACirc.). Incisor space (IS) was also measured in the mandibular casts. The mean values of all measurements except (M-M) in the mandibular casts were significantly reduced in the Maasai who had permanent central incisors extracted compared to the non-extracted Maasai and the Kikuyu. The mean incisor space in the Maasai with extractions was 6.3 mm compared to 11.7 mm in the non-extracted Maasai group. The extent of reduction of IS, C-C, C-C ACirc. and M-M ACirc. following extractions of the incisors may depend on the mesial drift of lateral incisors, jaw growth and soft tissue influence. The position of the tongue and occlusal relationship of the molars may prevent bucco-lingual movements maintaining a constant M-M. There was no significant difference in the mandibular cast dimensions of the non-extracted Maasai and the Kikuyu. Analysis of the maxillary cast dimensions of the Maasai with extraction, non-extracted Maasai and Kikuyu showed no significant differences suggesting that the extraction of mandibular incisors has no effect on maxillary arch dimensions. The variability in growth of the dento-alveolar complex itself may explain why the dental arch dimensions are similar in the Maasai and Kikuyu despite ethnic differences. There was no significant difference between the male and female dental arch dimensions.

Adolescent↗
PubMed1997

Effect of casting on forearm resistance vessels in young men.

The aim of this study was to determine whether physical deconditioning, induced by 6 wk of forearm casting, and the conditioning effects of recovery from casting would elicit changes in the response of forearm resistance vessels to substances that modulate vascular resistance. Forearm blood flow (FBF) responses to intrabrachial infusion of NGmonomethyl-L-arginine (LNMMA) and norepinephrine (NE) were examined in six subjects recovering from Colles', scaphoid, or metacarpal fractures within 72 h of cast removal and again after a 6-wk recovery period. Vascular responses were also examined in six noncasted controls. The FBF responses of casted and control subjects did not differ, and no changes occurred over the 6-wk study period. These results suggest that the effect of forearm casting and recovery from casting do not greatly influence control of vascular tone, including the basal activity of the NO dilator system in vivo.

Adult↗
PubMed2004

CAST2: identification and characterization of a protein structurally related to the presynaptic cytomatrix protein CAST.

The cytomatrix at the active zone (CAZ) is thought to define the site of Ca2+-dependent exocytosis of neurotransmitters. We have recently identified a novel CAZ protein from rat brain which we have named CAST (CAZ-associated structural protein). CAST forms a large molecular complex with other CAZ proteins such as Bassoon, RIM1 and Munc13-1, at least through direct binding to RIM1. Here, we have identified a rat protein that is structurally related to CAST and named it CAST2. Subcellular fractionation analysis of rat brain shows that CAST2 is also tightly associated with the postsynaptic density fraction. Like CAST, CAST2 directly binds RIM1 and forms a hetero-oligomer with CAST. In primary cultured rat hippocampal neurones, CAST2 co-localizes with Bassoon at synapses. Furthermore, immunoelectron microscopy reveals that CAST2 localizes to the vicinity of the presynaptic membrane of synapses in mouse brain. Sequence analysis reveals that CAST2 is a rat orthologue of the human protein ELKS. ELKS has also recently been identified as Rab6IP2 and ERC1. Accordingly, the original CAST is tentatively re-named CAST1. These results indicate that CAST2 is a new component of the CAZ and, together with CAST1, may be involved in the formation of the CAZ structure.

Adaptor Proteins, Signal Transducing↗
PubMed1991

A comparison of two methods for locating the intercuspal position (ICP) whilst mounting casts on an articulator.

The accuracy of two different techniques for locating casts in the intercuspal position (ICP) in a semi-adjustable articulator was assessed. The techniques for establishing the ICP were a polyether interdental registration, or location of the casts in a position of maximum interdigitation using tactile and visual methods. Fifty-three sets of study models were used in this investigation. Each set of study models was mounted on two occasions, once with each of the two techniques. The models were divided into two groups at random, and mounting and assessment procedures were performed using a single blind crossover design. The quality of the contacts between the mounted casts was compared with the results of an occlusal examination of the same subjects. Hand articulation of the casts prior to mounting the lower cast against the upper cast was a more accurate means of locating the ICP than the use of a low-viscosity polyether interdental registration material, unless there were difficulties in establishing the ICP by visual and tactile methods.

Dental Articulators↗
PubMed1990

Mechanisms of intranephronal proteinaceous cast formation by low molecular weight proteins.

Proteinaceous cast formation in the distal nephron of the kidney from low molecular weight proteinuria is a significant, but poorly characterized, cause of renal failure. To study this phenomenon, we: (a) microperfused the loop segment (LS) of rats in vivo with artificial tubule fluid (ATF) containing four different low molecular weight proteins, 0.01-50 mg/ml, to detect alterations in LS function, and (b) examined the interaction between several proteins and Tamm-Horsfall glycoprotein (THP) in vitro with turbidity and dynamic light-scattering measurements. Perfusion of the LS for less than 2 min with cast-forming proteins (Bence Jones protein [BJP3] and myoglobin) decreased chloride absorption and elevated early distal tubule fluid (ED) [Cl-], compared with results obtained with control perfusions that used ATF alone. BJP3 decreased chloride absorption in a concentration-dependent fashion. Perfusion with non-cast-forming proteins (albumin and BJP1) enhanced chloride absorption and decreased ED [Cl-]. In vitro, proteins that had isoelectric points (pI) greater than 5.1 aggregated with THP. Aggregation was enhanced with increasing [NaCl] or [CaCl2]. Albumin (pI 4.8) and beta-lactoglobulin (pI 5.1) did not coprecipitate. The molecular size of THP alone increased when [NaCl] greater than 80 mM. Thus, cast-forming proteins aggregated with THP in vitro and caused in vivo LS dysfunction, which elevated ED [Cl-], facilitating aggregation. In contrast, non-cast-forming proteins either did not interact with THP or lowered ED [Cl-], which did not provide an environment for aggregation. Altered LS function and interaction of some proteins with THP were related to different physicochemical properties of the proteins and independently contributed to the formation of proteinaceous casts in the kidney.

Animals↗
PubMed1992

Pathobiology of cast nephropathy from human Bence Jones proteins.

Renal failure is a common accompaniment of multiple myeloma and is usually due to cast nephropathy, or "myeloma kidney." To understand this lesion, four human Bence Jones proteins (BJP) were purified from the urine of volunteers who had either no evidence of renal dysfunction (BJP1) or renal failure from cast nephropathy (BJP2, BJP3, BJP4). When infused directly into the rat nephron in vivo, BJP2, BJP3, and BJP4 produced intraluminal obstruction by precipitating in the distal nephron; protein casts were never identified before the tip of the loop of Henle. Obstruction was related to the concentration of BJP in the perfusate. Addition of furosemide to the perfusate augmented obstruction in a concentration-dependent fashion. Pretreatment of rats with colchicine completely prevented obstruction and cast formation of perfused nephrons; beta-lumicolchicine did not prevent obstruction. Tamm-Horsfall glycoprotein purified from beta-lumicolchicine-treated and untreated rats coaggregated with BJP3 in vitro. Tamm-Horsfall glycoprotein from colchicine-treated rats did not contain sialic acid and did not aggregate with BJP3 in vitro. Thus, cast-forming human BJP coaggregated with Tamm-Horsfall glycoprotein and obstructed the rat distal nephron. Intranephronal obstruction was aggravated by decreasing extracellular fluid volume or adding furosemide. Finally, by decreasing secretion and altering the carbohydrate moiety of Tamm-Horsfall glycoprotein, colchicine prevented intraluminal cast formation and obstruction of the rat nephron.

Animals↗
PubMed2001

Consultations of children living near open-cast coal mines.

Because of local concerns, general practitioner consultation rates in children living in communities close to and away from open-cast mines were compared. Information on consultations was collected on 2,442 children 1-11 years of age living in five socioeconomically matched pairs of open-cast and control communities in northern England. The data collection periods were 6 weeks each during 1996-1997 and the 52-week periods preceding these weeks. Consultations were categorized as respiratory, skin and eye conditions (possibly exacerbated by particulate matter), or other conditions. Over the 6-week periods, children in 4/5 pairs of open-cast and control communities had similar consultation rates for all conditions combined [2.7 vs. 2.4 per person-year; odds ratio (OR) = 1.1; 95% confidence interval (CI), 0.96-1.3). Consultations were higher in the open-cast communities for respiratory, skin, and eye conditions (2.1 vs. 1.5 per person-year; OR = 1.4; 95% CI, 1.2-1.7), and respiratory conditions alone (1.5 vs. 1.1 per person-year; OR = 1.5; 95% CI, 1.2-1.8). However, increases in consultation rates in open-cast communities were generally not seen over the portions of the 52-week periods when the open-cast sites were either active or inactive.

Air Pollution↗
PubMed2002

Heritability of anthropometric phenotypes in caste populations of Visakhapatnam, India.

In this study, we used anthropometric data from six Andhra caste populations to examine heritability patterns of 23 anthropometric phenotypes (linear, craniofacial, and soft tissue measures) with special reference to caste differences. We obtained anthropometric data from 342 nuclear families from Brahmin, Reddy, Telaga, Nagara, Ag. Kshatriya, and Mala castes of Visakhapatnam, India. These caste groups represent the existing hierarchical stratification of Indian populations. We used a variance components approach to determine the heritability (h2) of these 23 anthropometric phenotypes (height, weight, BMI, etc.). The sample consisted of 1918 individuals ranging in age from 6 to 72 years (mean = 21.5, S.D. = 13.8). The heritabilities (h2 +/- S.E.) for all anthropometric traits for the entire sample were significant (p < 0.0001) and varied from 0.25 +/- 0.05 (BMI) to 0.61 +/- 0.05 (bizygomatic breadth) after accounting for sex, age, and caste effects. Since data on socioeconomic and nutritional covariates were available for a subset of families, we repeated the genetic analyses using this subset, which has yielded higher heritabilities ranging from 0.21 +/- 0.16 (head breadth) to 0.72 +/- 0.18 (nasal breadth). In general, craniofacial measurements exhibited higher h2 compared to linear measures. Breadth measurements and circumferences yielded more or less similar heritabilities. Age and sex effects were significant (p < 0.0001 ) for most of the traits, while the effects of caste, socioeconomic status, and nutritional status were inconsistent across the traits. In conclusion, anthropometric phenotypes examined in this study are under appreciable additive genetic influences.

Adolescent↗
PubMed2004

Photographs of study casts: an alternative medium for rating dental arch relationships in unilateral cleft lip and palate.

OBJECTIVE: To investigate the reliability of using photographs of study casts as an alternative to casts for rating dental arch relationships. DESIGN: Repeated-measures study. SETTING: Cleft Palate Center of the University Medical Center Nijmegen, Nijmegen, The Netherlands. PATIENTS: Records of children with complete unilateral cleft lip and palate (UCLP) (n = 49) at the age of 9 years were included. MEAN OUTCOME MEASURE(S): Statistics of intra- and interexaminer agreement. RESULTS: No significant differences were found between the rating of dental casts and photographs of dental casts, using the Goslon Yardstick. CONCLUSIONS: Photographs of dental casts provide a consistent, reproducible method for rating dental arch relationships in patients with UCLP at the age of 9 years and provide a reliable alternative to the application of the Goslon Yardstick on dental casts.

Child↗
PubMed2006

Genetic caste determination in harvester ants: possible origin and maintenance by cyto-nuclear epistasis.

While reproductive caste in eusocial insects is usually determined by environmental factors, in some populations of the harvester ants, Pogonomyrmex barbatus and P. rugosus, caste has been shown to have a strong genetic component. This system of genetic caste determination (GCD) is characterized by between-caste nuclear variation and high levels of mitochondrial haplotype variation between alternative maternal lineages. Two previous genetic models, involving a single nuclear caste-determining locus or interactions between two nuclear loci, respectively, have been proposed to explain the GCD system. We propose a new model based on interactions between nuclear and mitochondrial genes that can better explain the co-maintenance of distinct nuclear and mitochondrial lineages. In our model, females with coevolved cyto-nuclear gene complexes, derived from intra-lineage mating, develop into gynes, while females with disrupted cyto-nuclear complexes, derived from inter-lineage mating, develop into workers. Both haplodiploidy and inbreeding facilitate the buildup of such coevolved cyto-nuclear complexes within lineages. In addition, the opportunity for both intra-lineage and inter-lineage mating in polyandrous populations facilitates the accumulation of gyne-biasing genes. This model may also help to explain the evolution of workerless social, parasites. We discuss similarities of GCD and cytoplasmic male sterility in plants and how worker production of males would affect the stability of GCD. Finally, we propose experiments and observations that might help resolve the origin and maintenance of this unusual system of caste determination.

Animals↗
PubMed1989

[Accuracy of complete dental arch impressions and stone casts using a three-dimensional measurement system. Effect on accuracy of rubber impression materials and trays].

The purpose of this study was to investigate and compare the accuracy of complete dental arch impressions and stone casts made from two kinds of impression materials (addition type silicone and polysulfide rubber) and trays (custom tray and modified custom tray). In addition, the effect of quantity of gypsum was examined. Impressions were made from a metallic model of a simplified maxillary dentition. Impressions and stone casts were measured respectively using the three-dimensional measuring microscope. The results were as follows: 1. Distortion of impressions was so small that the reproducibility of impressions was superior three-dimensionally. 2. These kinds of impressions and trays did not influence the accuracy of impressions but had an effect on the accuracy of the stone casts. 3. Generally, the setting expansion of gypsum in the impression occurred in all directions. 4. Arch widths and lengths on the stone casts tended to increase in number. 5. Stone casts made from an addition/type silicone impression material and a custom tray were the most accurate because the combination of the impression material and tray effectively suppressed the setting expansion of gypsum. 6. By controlling the quantity of gypsum, the accuracy of stone casts could be improved.

Dental Impression Materials↗
PubMedDate not supplied

Master cast accuracy in single-tooth implant replacement cases: an in vitro comparison. A technical note.

PURPOSE: This in vitro study evaluated the accuracy of master casts obtained by using (1) copings modified by sandblasting and coating their roughened surfaces with impression adhesive before final impression procedures and (2) gold machined UCLA abutments as impression copings in final impression procedures for single-tooth implant replacement cases. MATERIALS AND METHODS: A polymeric resin model with a standard single implant was used to simulate a clinical situation. A group of 20 impressions were made using square impression copings sandblasted to roughen their external surfaces at a supragingival level and then coated with Impregum polyether adhesive; a second group of 20 impressions were made using gold machined UCLA abutments as impression copings. The castable part of the UCLA abutments was secured with resin to the gold machined section of the UCLA abutment to prevent movement of the castable part itself on the gold machined portion during the impression procedures; the castable portion of the UCLA was also coated with the Impregum polyether adhesive to improve the stability of the gold machined UCLA abutment inside the impression material. Master casts fabricated for both groups were analyzed to detect rotational position change of the hexagon on the implant replicas in the master casts with reference to the resin model. RESULTS: The rotational position changes of the hexagon on implant replicas were significantly less variable in the master casts obtained using gold machined UCLA abutments as impression copings than in the master casts achieved with the roughened square impression copings. DISCUSSION: Improved precision of the impression was achieved when the gold machined UCLA abutments were used as impression copings. CONCLUSION: This report suggests that using gold machined UCLA abutments as impression copings in the final impression procedures can enable the clinician to achieve a more accurate orientation of the implant replicas in the laboratory master casts for single-tooth implant replacement cases.

Air Abrasion, Dental↗
PubMedDate not supplied

Retention forces and seating discrepancies of implant-retained castings after cementation.

PURPOSE: The purpose of this in vitro study was to evaluate the influence of cement type and application technique on seating discrepancies and retention forces of noble alloy castings cemented on titanium abutments. MATERIALS AND METHODS: Eugenol-free zinc oxide (Freegenol), zinc phosphate (Harvard), glass ionomer (KetacCem), polycarboxylate (Durelon), and self-adhesive resin (RelyX Unicem) cements were used. The inner surfaces of the castings were either completely coated or half-coated with cement. Abutments were used as delivered with a machined surface for the first part of the study. Groups of 8 castings were cemented in both ways. For the second part of the study, the abutments were air-abraded (aluminum oxide, 50 microm particle size), and groups of 8 completely coated castings were cemented with all cements. Marginal discrepancies were measured before and immediately after cementation. Tensile tests were conducted to measure the retention forces. Statistical analysis was performed with pair-wise comparison using the Wilcoxon rank sum test modified by Bonferroni-Holm. RESULTS: Change in seating discrepancies did not differ significantly among the different application techniques. The median retention forces for completely-coated castings were 177 N for eugenol-free zinc oxide, 346 N for zinc phosphate, 469 N for glass ionomer, 813 N for polycarboxylate, and 653 N for self-adhesive resin. With respect to retention force, 3 significantly different groups (P < .05) were identified: (1) zinc oxide, (2) zinc phosphate/glass ionomer, and (3) polycarboxylate/self-adhesive resin. No differences in retention between the 2 coating techniques were found for any cement. However, air abrading the abutments resulted in increased retention of the castings for some of the cements. CONCLUSIONS: Half-coating of the restorations with cements did not result in reduced retention values compared to the complete coating technique, but air abrasion resulted in increased retention with some cements.

Air Abrasion, Dental↗
PubMedDate not supplied

Displacement of implant components from impressions to definitive casts.

PURPOSE: Four possible displacements of implant components from a patient model to a definitive cast were assessed to suggest a standard method of comparing the accuracies of implant impression techniques. MATERIALS AND METHODS: Two techniques for impression making were assessed: a nonsplinted open-tray technique and a light-curing resin splinted open-tray technique. A mandibular model with 5 parallel implants was fabricated. Five definitive casts were fabricated per technique. Using a computerized coordinate measuring machine, 5 part coordinate systems were established, and 7 sets of data were obtained for each sample. From the data, the amount of displacement while connecting components and the linear and angular displacement of components during impression making and cast fabrication were calculated. The Mann-Whitney test was used to determine significant differences between the impression techniques (P < .05). RESULTS: The average displacements while connecting impression copings and abutment replicas were 31.3 and 30.4 microm, respectively. Less displacement occurred in the nonsplinted group compared to the splinted group during impression making (P = .001) but greater displacement occurred in that group during definitive cast fabrication (P = .015). DISCUSSION: In contrast to previous studies, the current study excluded displacement resulting from component connection, because displacement from that source has no relation to impression technique and cannot be controlled. CONCLUSIONS: Connecting a component produced as great a displacement as that resulting solely from a impression or cast fabrication. The nonsplinted group was more accurate during impression making but less accurate during cast fabrication.

Acrylic Resins↗