Insights into Cruciform Sample Design.

Four different cruciform sample designs, based on the work of Abu-Farha et al., were studied in this paper. Key features of this design are a recessed pocket with fillet and re-entrant corners. These samples were shown via digital image correlation to achieve widely differing strain values inside and outside the pocket. From the results of these tests, there are two competing failure mechanisms in the sample. The pocket region is affected by stress concentrations caused by the fillet, and re-entrant notches lead to strain limited constraints similar to diffuse and localized necks in uniaxial samples. Balancing these two constraints determines the success or premature failure of the sample.

[Morpho-functional imaging in a patient with hyperparathyroidism and multifocal maxillary brown tumor]. / Imagerie morphologique et fonctionnelle des tumeurs brunes. À propos d'un cas de localisation maxillo-mandibulaire.

INTRODUCTION: Brown tumors are uncommon osteolytic lesions directly related to the increased osteoclastic activity due to hyperparathyroidism. CASE REPORT: A 37-year-old woman presented with hypercalcemia related to primary hyperparathyroidism. Multiple and bilateral maxillary osteolytic lesions showing intense fluorodesoxyglucose (FDG) uptake were noted in a positron emission tomography computed tomography (PET-CT). Diagnosis of maxillary brown tumors was discussed and confirmed by both orthopantomogram and magnetic resonance imaging. Left inferior parathyroid adenoma was detected by both cervical ultrasonography and parathyroid scintigraphy, and then surgically treated with consequent improvement of hyperparathyroidism. CONCLUSION: Our case emphasizes the necessity of a multidisciplinary diagnostic approach to optimize the interpretation of the available imaging, especially in unusual and unrecognized pathology as brown tumors.

Bone density comparison of selected carpal and tarsal bones: validation for their use in compression fracture fixation studies of scaphoid screws.

INTRODUCTION: To determine if trabecular, total and cortical bone densities of the capitate, navicular, cuboid, and first cuneiform were equivalent to those of the scaphoid, such that these bones could be used in place of the scaphoid in evaluating new headless scaphoid compression screws. METHODS: Fifty scaphoids, capitates, naviculars, cuboids, and first cuneiforms were harvested from fresh frozen cadavers. The trabecular, total and cortical bone densities were measured using pQCT technology and statistically compared. RESULTS: A paired t comparison between paired scaphoids and capitates showed no difference between the trabecular bone densities. However, their total bone and cortical densities were found to be different. An independent measures ANOVA comparison of the five bones, showed no significant difference in mean trabecular density between the capitates, naviculars and first cuneiforms when compared to the scaphoids. However, the mean total and cortical densities of the first cuneiforms were less than the scaphoids and the mean trabecular, total and cortical bone densities of the cuboids were all less than the scaphoids. DISCUSSION: Compression fracture fixation studies of headless compression screws could be conducted using the capitate, navicular, and first cuneiform as models of the scaphoid when the supply of scaphoids is limited.

Cofactor and tryptophan accessibility and unfolding of brain glutamate decarboxylase.

Cofactor and tryptophan accessibility of the 65-kDa form of rat brain glutamate decarboxylase (GAD) was investigated by fluorescence quenching measurements using acrylamide, I-, and Cs+ as the quenchers. Trp residues were partially exposed to solvent. I- was less able and Cs+ was more able to quench the fluorescence of Trp residues in the holoenzyme of GAD (holoGAD) than the apoenzyme (apoGAD). The fraction of exposed Trp residues were in the range of 30-49%. In contrast, pyridoxal-P bound to the active site of GAD was exposed to solvent. I- was more able and Cs+ was less able to quench the fluorescence of pyridoxal-P in holoGAD. The cofactor was present in a positively charged microenvironment, making it accessible for interactions with anions. A difference in the exposure of Trp residues and pyridoxal-P to these charged quenchers suggested that the exposed Trp residues were essentially located outside of the active site. Changes in the accessibility of Trp residues upon pyridoxal-P binding strongly supported a significant conformational change in GAD. Fluorescence intensity measurements were also carried out to investigate the unfolding of GAD using guanidine hydrochloride (GdnHCl) as the denaturant. At 0.8-1.5 M GdnHCl, an intermediate step was observed during the unfolding of GAD from the native to the denatured state, and was not found during the refolding of GAD from the denatured to native state, indicating that this intermediate step was not a reversible process. However, at >1.5 M GdnHCl for holoGAD and >2.0 M GdnHCl for apoGAD, the transition leading to the denatured state was reversible. It was suggested that the intermediate step involved the dissociation of native dimer of GAD into monomers and the change in the secondary structure of the protein. Circular dichroism revealed a decrease in the alpha-helix content of GAD from 36 to 28%. The unfolding pattern suggested that GAD may consist of at least two unfolding domains. Unfolding of the lower GdnHCl-resisting domain occurred at a similar concentration of denaturant for apoGAD and holoGAD, while unfolding of the higher GdnHCl-resisting domain occurred at a higher concentration of GdnHCl for apoGAD than holoGAD.

Identification of a contractile deficit in adult cardiac myocytes expressing hypertrophic cardiomyopathy-associated mutant troponin T proteins.

The direct effects of expressing hypertrophic cardiomyopathy-associated (HCM-associated) mutant troponin T (TnT) proteins on the force generation of single adult cardiac myocytes have not been established. Replication-defective recombinant adenovirus vectors were generated for gene transfer of HCM-associated I79N and R92Q mutant cardiac TnT cDNAs into fully differentiated adult cardiac myocytes in primary culture. We tested the hypothesis that the mutant TnT proteins would be expressed and incorporated into the cardiac sarcomere and would behave as dominant-negative proteins to directly alter calcium-activated force generation at the level of the single cardiac myocyte. Interestingly, under identical experimental conditions, the ectopic expression of the mutant TnTs was significantly less ( approximately 8% of total) than that obtained with expression of wild-type TnT ( approximately 35%) in the myocytes. Confocal imaging of immunolabeled TnT showed a regular periodic pattern of localization of ectopic mutant TnT that was not different than that in normal controls, suggesting that mutant TnT incorporation had no deleterious effects on sarcomeric architecture. Direct measurements of isometric force production in single cardiac myocytes demonstrated marked desensitization of submaximal calcium-activated tension, with unchanged maximum tension generation in mutant TnT-expressing myocytes compared with control myocytes. Collectively, these results demonstrate an impaired expression of the mutant protein and a disabling of cardiac contraction in the submaximal range of myoplasmic calcium concentrations. Our functional results suggest that development of new pharmacological, chemical, or genetic approaches to sensitize the thin-filament regulatory protein system could ameliorate force deficits associated with expression of I79N and R92Q in adult cardiac myocytes.

Stability of the contractile assembly and Ca2+-activated tension in adenovirus infected adult cardiac myocytes.

Adenovirus-mediated gene transfer into adult cardiac myocytes in primary culture is a potentially useful method to study the structure and function of the contractile apparatus. However, the consequences of adenovirus infection on the highly differentiated state of the cultured myocyte have not been determined. We report here a detailed analysis of myofilament structure and function over time in primary culture and after adenovirus infection. Adult rat ventricular myocytes in primary culture were infected with a recombinant adenovirus vector expressing either the LacZ or alkaline phosphatase reporter gene. Control and infected myocytes were collected at days 0-7 post-isolation/infection, and myofilament isoform expression was determined by SDS-PAGE and Western blot. Laser scanning densitometry showed that the alpha- to beta-myosin heavy chain ratio, the stoichiometry of the myosin light chains and the expression of the adult troponin T isoform did not change over time in culture or with adenovirus treatment. Importantly, examination of Ca2+-activated tension in single myocytes showed no change in the shape or position of the tension-pCa relationship in the control and adenovirus infected myocytes during primary culture. These results indicate that the structure and function of adult cardiac myocytes are stable in short term primary culture and are not affected by adenovirus infection per se, and therefore provide the foundation for the use of adenovirus-mediated myofilament gene transfer to study contractile apparatus structure and function in adult cardiac myocytes.

Slow skeletal troponin I gene transfer, expression, and myofilament incorporation enhances adult cardiac myocyte contractile function.

The functional significance of the developmental transition from slow skeletal troponin I (ssTnI) to cardiac TnI (cTnI) isoform expression in cardiac myocytes remains unclear. We show here the effects of adenovirus-mediated ssTnI gene transfer on myofilament structure and function in adult cardiac myocytes in primary culture. Gene transfer resulted in the rapid, uniform, and nearly complete replacement of endogenous cTnI with the ssTnI isoform with no detected changes in sarcomeric ultrastructure, or in the isoforms and stoichiometry of other myofilament proteins compared with control myocytes over 7 days in primary culture. In functional studies on permeabilized single cardiac myocytes, the threshold for Ca2+-activated contraction was significantly lowered in adult cardiac myocytes expressing ssTnI relative to control values. The tension-Ca2+ relationship was unchanged from controls in primary cultures of cardiac myocytes treated with adenovirus containing the adult cardiac troponin T (TnT) or cTnI cDNAs. These results indicate that changes in Ca2+ activation of tension in ssTnI-expressing cardiac myocytes were isoform-specific, and not due to nonspecific functional changes resulting from overexpression of a myofilament protein. Further, Ca2+-activated tension development was enhanced in cardiac myocytes expressing ssTnI compared with control values under conditions mimicking the acidosis found during myocardial ischemia. These results show that ssTnI enhances contractile sensitivity to Ca2+ activation under physiological and acidic pH conditions in adult rat cardiac myocytes, and demonstrate the utility of adenovirus vectors for rapid and efficient genetic modification of the cardiac myofilament for structure/function studies in cardiac myocytes.

Gene transfer into mouse embryonic stem cell-derived cardiac myocytes mediated by recombinant adenovirus.

The main purpose of this study was to examine, for the first time, the ability of recombinant adenovirus to mediate gene transfer into cardiac myocytes derived from mouse embryonic stem (ES) cells differentiating in vitro. In addition, observations were made on the effect of adenovirus infection on cardiac myocyte differentiation and contractility in this in vitro system of cardiogenesis. ES cell cultures were infected at various times of differentiation with a recombinant adenovirus vector (AdCMVlacZ) containing the bacterial lacZ gene under the control of the cytomegalovirus (CMV) promoter. Expression of the lacZ reporter gene was determined by histochemical staining for beta-galactosidase activity. LacZ expression was not detected in undifferentiated ES cells infected with AdCMVlacZ. In contrast, infection of differentiating ES cell cultures showed increasing transgene expression with continued time in culture. Expression in ES-cell-derived cardiac myocytes was demonstrated by codetection of beta-galactosidase activity and troponin T with indirect immunofluorescence. At 24 h postinfection, approximately 27% of the cardiac myocytes were beta-galactosidase positive, and lacZ gene expression appeared to be stable for up to 21 d postinfection. Adenovirus infection had no apparent effect on the onset, extent, or duration of spontaneously contracting ES-cell-derived cardiomyocytes, indicating that cardiac differentiation and contractile function were not significantly altered in the infected cultures. The demonstration of adenovirus-mediated gene transfer into ES-cell-derived cardiac myocytes will aid studies of gene expression with this in vitro model of cardiogenesis and may facilitate future studies involving the use of these myocytes for grafting experiments in vivo.

Embryonic stem cell cardiogenesis applications for cardiovascular research.

Mouse embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of the preimplantation blastocyst. These cells can be maintained in culture in an undifferentiated state, or they can be induced to differentiate in vitro into multiple cell types, including spontaneously beating cardiac myocytes. The ability to engineer these ES cells genetically, together with their noted rapid differentiation into cardiac myocytes in vitro, makes this a useful tool for the study of cardiac gene expression and function. This in vitro cardiogenesis system may be particularly advantageous for pharmacological studies focusing on discovery of cardioactive drugs and for specifying the functional alterations associated with ablated or mutated cardiac genes that result in a lethal phenotype in vivo. (Trends Cardiovasc Med 1997;7:63-68). © 1997, Elsevier Science Inc.

A programme of intervention for substance abuse following traumatic brain injury.

This article describes a pilot programme initiated in 1991 to address the problems of substance abuse among persons who have experienced traumatic brain injury (TBI). The model of treatment is community-based, using an interdisciplinary staff with expertise in TBI, vocational rehabilitation, and substance abuse treatment, to support and enhance existing services in the client's own community. The primary method of intervention is resource and service coordination. Six principles that serve as the underpinnings of the model are described, as are core and supplemental services and staffing patterns. Innovative components of the programme include the theoretical model of changing addictive behaviours used to guide treatment, and the development of community teams to facilitate a coordinated and integrated approach. The programme has relatively low start-up costs and can serve both urban and rural populations. Clinical experience and initial programme evaluation results suggest that substance abuse and vocational rehabilitation goals can be effectively attained using this model of service delivery.

[The endocrine psychosyndrome in the long term. III. A catamnestic reexamination of patients suffering from hypothalamo-hypopituitary dwarfism (author's transl)]. / Das endokrine Psychosyndrom im Langzeitverlauf. III. Langfristige Katamnesen von Kranken mit hypothalamo-hypophysärem Zwerg-oder Kleinwuchs.

Fifteen patients (4 females and 11 males) with hypothalamo-hypopituitary dwarfism underwent extensive psychiatric investigation in 1962-1965. A follow-up study of the personality development and social conditions was made in 1977. The age of the patients ranged from 31 to 56 years (the average being 40). As before, the main finding was an infantile personality with a defective psychosexual maturity. Only a few patients had reached a somehat adult, independent personality in spite of hormonal deficiencies. Several patients had continued to grow and attained a stature slightly below average. However, this subsequent growth scarcely influenced personality development. Depressive moods are now more frequent than before and among the more differentiated patients, the neurotic symptoms are mainly phobic fears. Almost all of the patients have discontinued treatment with hormonal substitutes (androgenes, cortison, thyrotropic hormone) inspite of persistent deficiency symptoms, because the outcome did not match their high expectations. The symptoms of the endocrine psychosyndrome seem of minor importance compared with the psychic infantilism and the reactions to the experience of dwarfism and missing puberty. One female has suffered several psychotic episodes which were understood as being partially of endocrine origin.