A 29-kilodalton Golgi soluble N-ethylmaleimide-sensitive factor attachment protein receptor (Vti1-rp2) implicated in protein trafficking in the secretory pathway

Expressed sequence tags coding for a potential SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) were revealed during data base searches. The deduced amino acid sequence of the complete coding region predicts a 217-residue protein with a COOH-terminal hydrophobic membrane anchor. Affinity-purified antibodies raised against the cytoplasmic region of this protein specifically detect a 29-kilodalton integral membrane protein enriched in the Golgi membrane. Indirect immunofluorescence microscopy reveals that this protein is mainly associated with the Golgi apparatus. When detergent extracts of the Golgi membrane are incubated with immobilized glutathione S-transferase alpha soluble N-ethylmaleimide-sensitive factor attachment protein (GST-alpha-SNAP), this protein was specifically retained. This protein has been independently identified and termed Vti1-rp2, and it is homologous to Vti1p, a yeast Golgi SNARE. We further show that Vti1-rp2 can be qualitatively coimmunoprecipitated with Golgi syntaxin 5 and syntaxin 6, suggesting that Vti1-rp2 exists in at least two distinct Golgi SNARE complexes. In cells microinjected with antibodies against Vti1-rp2, transport of the envelope protein (G-protein) of vesicular stomatitis virus from the endoplasmic reticulum to the plasma membrane was specifically arrested at the Golgi apparatus, providing further evidence for functional importance of Vti1-rp2 in protein trafficking in the secretory pathway.     

Quality control in the secretory pathway: the role of calreticulin, calnexin and BiP in the retention of glycoproteins with C-terminal truncations

Unlike properly folded and assembled proteins, most misfolded and incompletely assembled proteins are retained in the endoplasmic reticulum of mammalian cells and degraded without transport to the Golgi complex. To analyze the mechanisms underlying this unique sorting process and its fidelity, the fate of C-terminally truncated fragments of influenza hemagglutinin was determined. An assortment of different fragments was generated by adding puromycin at low concentrations to influenza virus-infected tissue culture cells. Of the fragments generated, < 2% was secreted, indicating that the system for detecting defects in newly synthesized proteins is quite stringent. The majority of secreted species corresponded to folding domains within the viral spike glycoprotein. The retained fragments acquired a partially folded structure with intra-chain disulfide bonds and conformation-dependent antigenic epitopes. They associated with two lectin-like endoplasmic reticulum chaperones (calnexin and calreticulin) but not BiP/GRP78. Inhibition of the association with calnexin and calreticulin by the addition of castanospermine significantly increased fragment secretion. However, it also caused association with BiP/GRP78. These results indicated that the association with calnexin and calreticulin was involved in retaining the fragments. They also suggested that BiP/GRP78 could serve as a backup for calnexin and calreticulin in retaining the fragments. In summary, the results showed that the quality control system in the secretory pathway was efficient and sensitive to folding defects, and that it involved multiple interactions with endoplasmic reticulum chaperones.     

In search of shared and nonshared environmental factors in security of attachment: A behavior-genetic study of the association between sensitivity and attachment security.

The current article presents results from a twin study of genetic and environmental components of maternal sensitivity and infant attachment and their association. The sample consisted of 136 twin pairs from 2 sites: Leiden, the Netherlands, and London, UK. Maternal sensitivity was assessed in the home at 9-10 months, and infant attachment security was observed in the laboratory at 12 months. The study yielded little evidence that genetic factors are involved in variations between twins in maternal sensitivity ratings but did find that shared variance in maternal sensitivity was able to account for some of the similarity between twins in attachment security. Weak nonshared associations between sensitivity and attachment appeared to suppress the magnitude of the correlation between attachment and sensitivity in twin children. The results could indicate that the attachment security of one twin may depend on the relationship the parent has with the other twin. The results are brought to bear on the validity of attachment theory as a theory of primarily shared environmental effects in children's development and the continuing challenge posed to attachment theory by within-family differences in socioemotional processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A dominant-negative clathrin mutant differentially affects trafficking of molecules with distinct sorting motifs in the class II major histocompatibility complex (MHC) pathway

The role of clathrin in intracellular sorting was investigated by expression of a dominant-negative mutant form of clathrin, termed the hub fragment. Hub inhibition of clathrin-mediated membrane transport was established by demonstrating a block of transferrin internalization and an alteration in the intracellular distribution of the cation-independent mannose-6-phosphate receptor. Hubs had no effect on uptake of FITC-dextran, adaptor distribution, organelle integrity in the secretory pathway, or cell surface expression of constitutively secreted molecules. Hub expression blocked lysosomal delivery of chimeric molecules containing either the tyrosine-based sorting signal of H2M or the dileucine-based sorting signal of CD3gamma, confirming a role for clathrin-coated vesicles (CCVs) in recognizing these signals and sorting them to the endocytic pathway. Hub expression was then used to probe the role of CCVs in targeting native molecules bearing these sorting signals in the context of HLA-DM and the invariant chain (I chain) complexed to HLA-DR. The distribution of these molecules was differentially affected. Accumulation of hubs before expression of the DM dimer blocked DM export from the TGN, whereas hubs had no effect on direct targeting of the DR-I chain complex from the TGN to the endocytic pathway. However, concurrent expression of hubs, such that hubs were building to inhibitory concentrations during DM or DR-I chain expression, caused cell surface accumulation of both complexes. These observations suggest that both DM and DR-I chain are directly transported to the endocytic pathway from the TGN, DM in CCVs, and DR-I chain independent of CCVs. Subsequently, both complexes can appear at the cell surface from where they are both internalized by CCVs. Differential packaging in CCVs in the TGN, mediated by tyrosine- and dileucine-based sorting signals, could be a mechanism for functional segregation of DM from DR-I chain until their intended rendezvous in late endocytic compartments.     

Absence of association between delta and gamma2 subunits in native GABA(A) receptors from rat brain

We investigated the possible association between delta and gamma2 subunits in native GABA(A) receptors, from different rat brain regions, using subunit-specific anti-delta and anti-gamma2 antibodies. Previous reports have provided somewhat controversial results, indicating both the presence and the absence of association between these two subunits in native receptors. Our results indicate the absence of co-localization between delta and gamma2 subunits. In immunoprecipitation experiments, anti-delta antibody consistently immunoprecipitated [3H]muscimol binding activity (GABA binding sites) from all brain areas tested (10-20% of the total binding). However, under the same conditions, no significant [3H]flumazenil or [3H]ethyl 8-azido-6-dihydro-5-methyl-6-oxo-4H-imidazol[1,5-a]-[1,4]benzodiazepine- 3-carboxylate (Ro15-4513) binding (benzodiazepine binding sites) activity was detected in the immunopellets. These results indicate the absence of association between delta and gamma2 subunits. This question was directly addressed by immunopurification and Western blot experiments. As expected, no gamma2 subunits were detected in anti-delta immunoaffinity purified receptors. Conversely, no delta subunits were identified in anti-gamma2 immunopurified receptors. Thus, these results demonstrate the absence of association between delta and gamma2 subunits in native GABA(A) receptors. Finally, our results also indicate the relevance of the solubilization conditions on the apparent association between different subunits of the native GABA(A) receptor complex.     

A C-type natriuretic peptide from the venom of the platypus (Ornithorhynchus anatinus): structure and pharmacology

College students' intuitive judgments about covariations between height, weight, and body fat were assessed in three experiments using responses to a series of propositional statements as the dependent variable. In Exp. 1, judgments were rendered without explicit exposure to a prior database. In Exps. 2 and 3, however, databases were studied prior to these judgments. Remarkable consistencies in judgments of weight and body fat, height and weight as well as of height and body fat were obtained across experiments. At best, there was little evidence that the databases influenced the judged covariations among these variables. Whereas judgments about weight and body fat were unambiguous and consistent with the actual positive correlation between weight and body fat, judgments about height and weight as well as height and body fat were less clearcut. What was clear, however, was that these judgments were highly similar. Implications of these findings from previous research that suggest that presence of a perceived negative correlation between height and body fat are discussed.     

Expression and purification of the extracellular ligand-binding domain of the atrial natriuretic peptide (ANP) receptor: monovalent binding with ANP induces 2:2 complexes

The receptor for atrial natriuretic peptide (ANP) is a type-I transmembrane protein containing an extracellular ligand-binding domain, a single transmembrane sequence, an intracellular kinase-homologous domain, and a guanylate cyclase (GCase) domain. Binding of ANP to the extracellular domain causes activation of the GCase domain by an as yet unknown mechanism. To facilitate studies of the receptor structure and signaling mechanism, we have expressed the extracellular ANP-binding domain of rat ANP receptor (NPR-ECD) in a water-soluble form. NPR-ECD was purified to homogeneity by ANP-affinity chromatography. SDS-PAGE gave a single 61-kDa band, which coincided with a radioactive band obtained by photoaffinity-labeling with N4alpha-azidobenzoyl-125I-ANP(4-28). Edman degradation gave a single amino-terminal sequence expected for the mature protein. Both trifluoromethanesulfonic acid and peptide-N-glycosidase F treatments yielded a 50-kDa band, indicating N-glycosylation. The molecular mass of 57 725 Da determined by mass spectrometry indicates the carbohydrate content at 16%. NPR-ECD bound ANP with an affinity comparable to that of the full-length receptor. The ligand selectivity of NPR-ECD (in the order ANP > brain natriuretic peptide > C-type natriuretic peptide) was also similar to that of the full-length receptor. HPLC gel filtration of NPR-ECD gave a peak with an apparent mass of 74 kDa. Preincubation with ANP generated a new 150-kDa peak with a concomitant decrease of the 74-kDa peak. This shift in peak positions was ANP concentration-dependent and was complete at the NPR-ECD-to-ANP molar ratio of 1:1, indicating equimolar binding. The change in the apparent native molecular weight from 74 to 150 kDa suggests that binding causes dimerization of the NPR-ECD:ANP complex to yield an [NPR-ECD:ANP]2 complex.     

Characterization of phosphotyrosine binding motifs in the cytoplasmic domain of platelet/endothelial cell adhesion molecule-1 (PECAM-1) that are required for the cellular association and activation of the protein-tyrosine phosphatase, SHP-2

Recent studies have shown that the Src homology-2 (SH2) domain-containing protein-tyrosine phosphatase, SHP-2, associates with the cytoplasmic domain of PECAM-1 as it becomes tyrosine-phosphorylated during platelet aggregation: a process that can be mimicked in part by small synthetic phosphopeptides corresponding to the cytoplasmic domain of PECAM-1 encompassing tyrosine residues Tyr-663 or Tyr-686. To further examine the molecular requirements for PECAM-1/SHP-2 interactions, we generated human embryonic kidney (HEK)-293 cell lines that stably expressed mutant forms of PECAM-1 harboring tyrosine to phenylalanine (Tyr --> Phe) mutations in the cytoplasmic domain. Y663F and Y686F forms of PECAM-1 were tyrosine-phosphorylated to a somewhat lesser extent than wild-type PECAM-1, and a doubly substituted Y663,686F form of PECAM-1 failed to become tyrosine-phosphorylated, suggesting that the PECAM-1 cytoplasmic domain tyrosine residues 596, 636 and 701 do not serve as substrates for cellular kinases. Interestingly, SHP-2 binding was lost when either Tyr-663 or Tyr-686 were changed to phenylalanine, indicating that both residues are required for SHP-2/PECAM-1 association. Although PECAM-1 phosphopeptides NSDVQpY663TEVQV and DTETVpY686SEVRK stimulated the catalytic activity of the phosphatase to a similar extent, surface plasmon resonance studies revealed that the Tyr-663-containing peptide had approximately 10-fold higher affinity for SHP-2 than did the Tyr-686 peptide. Finally, peptido-precipitation analysis showed that the NH2-terminal SH2 domain of SHP-2 reacted preferentially with the Tyr-663 PECAM-1 phosphopeptide, while the Tyr-686 phosphopeptide associated only with the COOH-terminal SH2 domain of the phosphatase. Together, these data provide a molecular model for PECAM-1/SHP-2 interactions that may shed light on the downstream events that follow PECAM-1-mediated interactions of vascular cells.     

A monomeric human C4b-binding protein (C4bp) more efficiently inactivates C3b than natural C4bp: participation of C-terminal domains in factor I-cofactor activity

We designed a cDNA construct encoding an artificial membrane molecule consisting of all 8 short consensus repeats (SCRs) of human monomeric C4b-binding protein (C4bp) followed by DAF's GPI anchor, named mC4bp, and expressed the protein on swine endothelial cells (SEC). At the same level of expression, mC4bp protected host cells as effectively as DAF, the most potent complement (C) regulator on the membrane. This result was unexpected from the reported functional properties of natural multimeric C4bp. Here, we investigated the mechanism whereby mC4bp has potent cell-protective activity. Our results were as follows: (1) mC4bp serves more efficiently as a methylamine-treated C3 (C3ma)-inactivating factor I-cofactor than natural C4bp and as efficiently as MCP as a methylamine-treated (C4ma)-inactivating cofactor by fluid-phase cofactor assay: (2) the potency of C3ma inactivation by mC4bp and factor I is quite high compared to those of other cofactors: (3)blocking studies using mAbs against C4bp suggested that both the 48 kDa N-terminal fragment and the C-terminal domain near the portion responsible for bundle formation participate in the high C3ma-inactivating capacity of mC4bp. Thus, acquiring high C3ma-inactivating capacity secondary to monomeric alteration leads to high C regulatory activity of mC4bp. These results infer that mC4bp differs from C4bp in its potent factor I-cofactor activity and is a good candidate as a safeguard against hyperacute rejection of xenografts.     

Bionomics of Cuterebra austeni (Diptera: Cuterebridae) and its association with Neotoma albigula (Rodentia: Cricetidae) in the southwestern United States

Cuterebra austeni Sabrosky causes cutaneous myiasis in white-throated woodrats, Neotoma albigula, in the southwestern United States. In central and southern Arizona and southwestern New Mexico, this species is bivoltine. Adult flies are active at hilltop aggregation sites from early spring through mid-May and again to a lesser extent in the fall months. Eggs produced from laboratory matings of adult flies hatched in response to warm breath (34-36 degrees C) 6-8 d after oviposition. Oviposition takes place around burrow entrances and near the bases of Opuntia cacti. In the wild, myiasis occurs in woodrats primarily during the spring months, with a small second peak during the fall. Larvae develop in cutaneous warbles in the sternal and the ventral cervical area of N. albigula and complete development in 33 d. Woodrats do not appear to be affected seriously by the presence of 1-5 larvae. Morphological changes in larvae and pupae are described through to adult eclosion.     

Signal-induced degradation of I(kappa)B(alpha): association with NF-kappaB and the PEST sequence in I(kappa)B(alpha) are not required

Signal-induced degradation of I(kappa)B(alpha) via the ubiquitin-proteasome pathway requires phosphorylation on residues serine 32 and serine 36 followed by ubiquitination on lysines 21 and 22. We investigated the role of other regions of I(kappa)B(alpha) which may be involved in its degradation. Here we report that the carboxy-terminal PEST sequence is not required for I(kappa)B(alpha) signal-induced degradation. However, removal of the PEST sequence stabilizes free I(kappa)B(alpha) in unstimulated cells. We further report that a PEST deletion mutant does not associate well with NF-(kappa)B proteins but is degraded in response to signal. Therefore, we conclude that both association with NF-(kappa)B and a PEST sequence are not required for signal-induced I(kappa)B(alpha) degradation. Additionally, the PEST sequence may be required for constitutive turnover of free I(kappa)B(alpha).     

Lipoprotein(a) and inflammation in human coronary atheroma: association with the severity of clinical presentation

OBJECTIVES: The purpose of this study was the investigation of the in vivo role of lipoprotein(a) [Lp(a)] and inflammatory infiltrates in the human coronary atherosclerotic plaque and their correlation with the clinical syndrome of presentation. BACKGROUND: Lipoprotein(a) is an atherogenic and thrombogenic lipoprotein, and has been implicated in the pathogenesis of acute coronary syndromes. Lipoprotein(a) induces monocyte chemoattraction and smooth muscle cell activation in vitro. Macrophage infiltration is considered one of the mechanisms of plaque rupture. METHODS: This study of atherectomy specimens investigated the in vivo role of Lp(a) at different stages of the atherogenic process, and its relationship with macrophage infiltration. We examined coronary atheroma removed from 72 patients with stable or unstable angina. Specimens were stained with antibodies specific for Lp(a), macrophages (KP-1), and smooth muscle cells (alpha-actin). Morphometric analysis was used to quantify the plaque areas occupied by each of the three antigens, and their colocalization. RESULTS: All specimens had localized Lp(a) staining; the mean fractional area was 58.2%. Ninety percent of the macrophage areas colocalized with Lp(a) positive areas, whereas 31.3% of the smooth muscle cell areas colocalized with Lp(a) positive areas. Patients with unstable angina (n = 46) had specimens with larger mean plaque Lp(a) areas than specimens from stable angina patients (n = 26): 64.4% versus 47.7% (p = 0.004). Unstable angina patients with rest pain (n = 28) had greater mean plaque Lp(a) area than unstable angina patients with crescendo exertional pain (n = 18): 71.1% versus 52.4% (p < 0.001). Mean KP-1 area was 31.2% in unstable rest angina versus 18.3% in stable angina (p = 0.05); alpha-actin area was greater in stable (48.5%) and crescendo exertional angina (48.8%) than in rest angina (30.4%). The strongest correlation between plaque KP-1 and Lp(a) area was in unstable rest angina (r = 0.88, p < 0.001), and between alpha-actin and Lp(a) areas in the crescendo exertional angina (r = 0.62, p < 0.01). CONCLUSIONS: Lipoprotein(a) is ubiquitous in human coronary atheroma. It is detected in larger amounts in tissue from culprit lesions in patients with unstable compared to stable syndromes, and has significant colocalization with plaque macrophages. A correlation of plaque alpha-actin and Lp(a) area suggests a role of Lp(a) in plaque growth.     

Missense mutation in a von Willebrand factor type A domain of the alpha 3(VI) collagen gene (COL6A3) in a family with Bethlem myopathy

OBJECTIVE: The purpose of this retrospective study was to examine the value of whole-body nuclear medicine imaging and to evaluate the typical scintigraphic pattern of sternocostoclavicular hyperostosis (SCCH) and/or pustulotic arthroosteitis (PAO). In this entity the correct diagnosis is frequently missed because of uncharacteristic changes in other imaging modalities. MATERIALS AND METHODS: Forty-nine patients (age range 15-65 years old, mean age 36 years) with sternocostoclavicular hyperostosis (SCCH) and/or pustulotic arthroosteitis (PAO) were examined with whole-body scintigraphy and conventional radiography. RESULTS: Forty-three of 49 patients with SCCH/PAO showed a characteristic "bullhead"-like high tracer uptake of the sternocostoclavicular region with the manubrium sterni representing the upper skull and the inflamed sternoclavicular joints corresponding to the horns (= bullhead sign). Scintigraphy revealed additional skeletal manifestations (spondylitis, sacroiliitis, osteitis) in 33 of 49 patients with SCCH and/or PAO. CONCLUSIONS: Bone scintigraphy is the imaging modality of choice for the diagnosis of skeletal involvement in PAO. Nuclear medicine reveals unexpected locations and shows the typical pattern of focal hot spots of the spine, sacroiliac joints and/or appendicular skeleton in the large majority of cases in combination with a bullhead-like tracer uptake of the sternocostoclavicular region. The bullhead sign is the typical and highly specific scintigraphic manifestation of SCCH and PAO in radionuclide bone scans and helps to avoid unnecessary biopsies.     

A polymorphism observed in the experimentally successful peptide vaccine sequence derived from Theileria sergenti piroplasm major surface antigen (p33)

A polymorphism in the experimentally successful peptide vaccine sequence (EVVWKEKKEVKDLDA, amino acids 134-148) derived from the 33 kDa piroplasm major surface antigen (p33) of Theileria sergenti was examined. The vaccine sequences obtained by PCR amplification and sequencing of the p33 gene from a total of 15 parasite-infected cattle blood samples collected from 4 prefectures through Hokkaido to Kumamoto revealed the two major sequences (Ikeda and Chitose stock types) either of which was identified in all samples. Since the peptide vaccine develops the parasite species- or stock-specific immunity in the animals, an application of the two major peptide sequences as cocktailed vaccine should be evaluated for a practical use of this strategy to controlling T. sergenti infection in Japan.     

Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) proteolysis in patients with colorectal cancer: possible association with the metastatic potential of the tumor

The limited proteolysis of insulin-like growth factor (IGF)-binding protein (IGFBP)-3 is a key event in the regulation of endocrine bioavailability of IGFs. Here, we investigated IGFBP-3 and IGFBP-3 proteolysis in serum from patients with colorectal cancer both before and at different times following surgery. In vivo IGFBP-3 proteolysis, estimated by immunoblot analysis of IGFBP-3 fragments in serum, and in vitro IGFBP-3 protease activity of serum, estimated by a 125I-IGFBP-3 degradation assay, allowed us to identify 2 groups of patients (IGF-M vs. IGF-NM) with respect to their status for mobilizing the IGF system. In IGF-M patients, in vivo and in vitro IGFBP-3 proteolysis were significantly elevated (156% and 181% of the age-matched control pool, respectively) and accompanied by a decrease in intact IGFBP-3 (38% of the control pool). The IGFBP-3 proteolytic processing was further increased in response to surgical ablation of the tumor (mean increase 45-55%), then gradually returned to levels comparable with controls. In contrast, IGF-NM patients exhibited a minimal alteration of in vitro IGFBP-3 protease activity and even an inhibition of in vivo IGFBP-3 proteolysis, whereas intact IGFBP-3 was unaltered when compared with controls. Moreover, this pattern was not further significantly altered in response to the surgical stress. None (0/6) of the IGF-M patients vs. 70% (5/7) of the IGF-NM patients developed a metastatic disease (median duration of follow-up 26 months). Neither elevated amounts of pro-IGF-II nor presence of detectable IGFBP-3 protease inhibitors in the circulation could explain the observed suppression of IGFBP-3 proteolytic processing in IGF-NM patients. These results indicate that inhibition of IGFBP-3 proteolysis and invasive properties of cancer cells are related in colorectal cancer patients.     

A peptide sequence from platelet factor 4 (CT-112) is effective in the treatment of type II collagen induced arthritis in mice

OBJECTIVE: Platelet factor 4 (PF-4) is a critical alpha chemokine in inflammation and injury responses, with multiple effects upon cellular activities. Discrete peptide sequences of the PF-4 molecule have been shown to retain biological activity. Our aim was to examine the influence of the PF-4 derived octapeptide (CT-112; TTSQVRPR) on type II collagen induced arthritis in mice, to determine if this peptide exhibited antiinflammatory properties. METHODS: DBA/1 mice were treated with CT-112 from either the time of immunization with type II collagen or from the initial onset of arthritis. RESULTS: CT-112 both prevented the development of arthritis in mice treated prophylactically and reduced progression of disease in animals treated therapeutically, and was active when delivered by either subcutaneous injection or oral gavage. No marked immunosuppressive effects were observed during CT-112 treatment, with only moderate decrease in antibody levels and mitogen responses. A significant reduction of the circulating levels of IL-1 was a consistent finding in mice treated therapeutically with CT-112. CONCLUSION: These data suggest PF-4 derived octapeptide exerts antiinflammatory effects of experimental arthritis in mice.     

A major T cell determinant from the influenza virus hemagglutinin (HA) can be a cryptic self peptide in HA transgenic mice

A single low dose of the neurotoxin: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) results paradoxical sleep deprivation and reduction in food intake without any detectable motor deficiencies. In the present study we monitored the in vivo extracellular levels of monoamines and their metabolites following intraperitoneal (i.p.) administration of a single dose of MPTP (5 mg/kg). Microdialysates were collected from the ventrobasal thalamic nucleus (VB) of Halothane anesthetized rat. We found a significant decrease in noradrenaline (NA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) levels and a significant increase in 3,4-dihydroxyphenylalanine (DOPA) concentration whereas amino acid levels were unchanged throughout the 4-hour long perfusion. We found no significant difference in the post mortem release of NA and DOPA between the control and MPTP treated animals, suggesting that the intracellular NA pool were maintained. The above findings support the idea that the neurochemical mechanism of rapidly developing and transient behavioral changes induced by MPTP may be an immediate decrease in monoaminergic transmission and metabolism following MPTP injection.     

Mutations in the N-terminal globular domain of the type X collagen gene (COL10A1) in patients with Schmid metaphyseal chondrodysplasia

STATEMENT OF PROBLEM: Improved dental stone has been widely used for producing dies for the fabrication of restorations with the lost-wax technique. Improved dental stone is used for several reasons, but it is selected most often because of its reasonable cost, ease of use, and ability to produce consistent results. PURPOSE: This study evaluated the ability of an epoxy resin die material and a type IV dental stone to dimensionally reproduce a custom-fabricated metal die. MATERIAL AND METHODS: Dies were fabricated and measurements were made from three reference lines. Measurements were repeated three times for the master die and for the specimen dies. A mean measurement and percent relative change for each dimension was calculated. RESULTS: A significant difference in the relative change for die height was found between the groups studied (p < 0.003). CONCLUSIONS: This epoxy die system will provide a degree of dimensional accuracy comparable to gypsum when used with addition silicone impression material.