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Biomedical subjects

S A Moore

Publications and source records attributed to S A Moore.

At least 37 records · Page 2Linked to original sources
PubMed2000

Expression of gamma -sarcoglycan in smooth muscle and its interaction with the smooth muscle sarcoglycan-sarcospan complex.

The sarcoglycan complex in striated muscle is a heterotetrameric unit integrally associated with sarcospan in the dystrophin-glycoprotein complex. The sarcoglycans, alpha, beta, gamma, and delta, are mutually dependent with regard to their localization at the sarcolemma, and mutations in any of the sarcoglycan genes lead to limb-girdle muscular dystrophies type 2C-2F. In smooth muscle beta- and delta-sarcoglycans are associated with epsilon-sarcoglycan, a glycoprotein homologous to alpha-sarcoglycan. Here, we demonstrate that gamma-sarcoglycan is also a component of the sarcoglycan complex in the smooth muscle. First, we show the presence of gamma-sarcoglycan in a number of smooth muscle-containing organs, and we verify the existence of identical transcripts in skeletal and smooth muscle. The specificity of the expression of gamma-sarcoglycan in smooth muscle was confirmed by analysis of smooth muscle cells in culture. Next, we provide evidence for the association of gamma-sarcoglycan with the sarcoglycan-sarcospan complex by biochemical analysis and comparison among animal models for muscular dystrophy. Moreover, we find disruption of the sarcoglycan complex in the vascular smooth muscle of a patient with gamma-sarcoglycanopathy. Taken together, our results prove that the sarcoglycan complex in vascular and visceral smooth muscle consists of epsilon-, beta-, gamma-, and delta-sarcoglycans and is associated with sarcospan.

Amino Acid Sequence↗
PubMed2000

Molecular and genetic characterization of sarcospan: insights into sarcoglycan-sarcospan interactions.

Autosomal recessive limb girdle muscular dystrophies 2C-2F represent a family of diseases caused by primary mutations in the sarcoglycan genes. We show that sarcospan, a novel tetraspan-like protein, is also lost in patients with either a complete or partial loss of the sarcoglycans. In particular, sarcospan was absent in a gamma-sarcoglycanopathy patient with normal levels of alpha-, beta- and delta-sarcoglycan. Thus, it is likely that assembly of the complete, tetrameric sarcoglycan complex is a prerequisite for membrane targeting and localization of sarcospan. Based on our findings that sarcospan is integrally associated with the sarcoglycans, we screened >50 autosomal recessive muscular dystrophy cases for mutations in sarcospan. Although we identified three intragenic polymorphisms, we did not find any cases of muscular dystrophy associated with primary mutations in the sarcospan gene. Finally, we have identified an important case of limb girdle muscular dystrophy and cardiomyopathy with normal expression of sarcospan. This patient has a primary mutation in the gamma-sarcoglycan gene, which causes premature truncation of gamma-sarcoglycan without affecting assembly of the mutant gamma-sarcoglycan into a complex with alpha-, beta- and delta-sarcoglycan and sarcospan. This is the first demonstration that membrane expression of a mutant sarcoglycan-sarcospan complex is insufficient in preventing muscular dystrophy and cardiomyopathy and that the C-terminus of gamma-sarcoglycan is critical for the functioning of the entire sarcoglycan-sarcospan complex. These findings are important as they contribute to a greater understanding of the structural determinants required for proper sarcoglycan-sarcospan expression and function.

Adult↗
PubMed2000

FSH dystrophy 4q35 deletion in patients presenting with facial-sparing scapular myopathy.

OBJECTIVE: To evaluate the incidence of the facioscapulohumeral dystrophy (FSHD) 4q35 deletion in patients with facial-sparing scapular myopathy. BACKGROUND: Scapular winging is typical of FSHD but may also be prominent in other muscle disorders including scapuloperoneal syndromes. With DNA testing, it is possible to determine if patients with facial-sparing scapular myopathy have FSHD. METHODS: Fourteen of 17 unrelated patients with facial-sparing scapular myopathy, seen over a 7-year period at a regional neuromuscular center, agreed to have DNA testing for FSHD. The clinical and laboratory features of these patients were also noted. RESULTS: Of the 14 patients, 10 (71%) had restriction fragments consistent with the 4q35 deletion. The mean size of the smaller fragment following EcoRI digestion was 29.5 kb (range 20 to 39). The mean age at onset was 19.9 years; at presentation, 44.7 years. Except for the absence of facial weakness, most patients had clinical and laboratory features otherwise consistent with FSHD. Five patients (50%) had a positive family history of similar weakness. Following removal of outliers, the Pearson correlation coefficient (r) value between EcoRI fragment size and age at onset was 0.64, and between fragment size and limb muscle strength, 0.64. CONCLUSION: The FSHD 4q35 deletion was found in 71% of the facial-sparing scapular myopathy patients. They otherwise resemble typical FSHD patients in age at onset, physical characteristics, and association between fragment size and disease severity.

Adult↗
PubMed2000

Disruption of the beta-sarcoglycan gene reveals pathogenetic complexity of limb-girdle muscular dystrophy type 2E.

Limb-girdle muscular dystrophy type 2E (LGMD 2E) is caused by mutations in the beta-sarcoglycan gene, which is expressed in skeletal, cardiac, and smooth muscle. beta-sarcoglycan-deficient (Sgcb-null) mice developed severe muscular dystrophy and cardiomyopathy with focal areas of necrosis. The sarcoglycan-sarcospan and dystroglycan complexes were disrupted in skeletal, cardiac, and smooth muscle membranes. epsilon-sarcoglycan was also reduced in membrane preparations of striated and smooth muscle. Loss of the sarcoglycan-sarcospan complex in vascular smooth muscle resulted in vascular irregularities in heart, diaphragm, and kidneys. Further biochemical characterization suggested the presence of a distinct epsilon-sarcoglycan complex in skeletal muscle that was disrupted in Sgcb-null mice. Thus, perturbation of vascular function together with disruption of the epsilon-sarcoglycan-containing complex represents a novel mechanism in the pathogenesis of LGMD 2E.

Animals↗
PubMed2000

Clopidogrel and coronary stenting: what is the next question?

Today, following coronary stenting, clopidogrel has largely replaced ticlopidine as part of combination antiplatelet therapy following coronary stenting primarily due to its better tolerability. While there is no randomized, blinded, efficacy trial of ticlopidine versus clopidogrel, there are ample data from a number of observational studies, randomized non-blinded trials, and a randomized blinded safety trial to prove that clopidogrel is not only safer than ticlopidine, but also at least as efficacious following stenting. With over 10,000 treated patients, pooled data suggest similar rates of stent thrombosis (clopidogrel 0.98% vs. ticlopidine 0.98%) and lower rates of major adverse cardiac events with clopidogrel (clopidogrel 1.63% vs. ticlopidine 4.52%, p<0.001), with a clear advantage for clopidogrel regarding adverse events (clopidogrel 5.91% vs. ticlopidine 9.75%, p<0.001). With clopidogrel's superior safety and at least equivalent efficacy, the question of "which thienopyridine?" post-stenting has been answered. Now the questions "how much?", "how soon?" and "how long?" must be addressed. The Clopidogrel for the Reduction of Events During Observation (CREDO) trial is a multi-center, double-blind, randomized trial designed to answer these remaining questions. CREDO will evaluate the efficacy and safety of clopidogrel pretreatment versus no pretreatment, and prolonged (1 year), versus short-term (1 month) dual antiplatelet therapy in 2,000 patients undergoing planned or highly probable coronary intervention with a stent.

Clinical Trials as Topic↗
PubMed2000

Intracellular accumulation and reduced sarcolemmal expression of dysferlin in limb--girdle muscular dystrophies.

Dysferlin has recently been identified as a novel gene involved in limb-girdle muscular dystrophy type 2B (LGMD2B) and its allelic disease, Miyoshi myopathy. The predicted structure of dysferlin suggests that it is a transmembrane protein possibly involved in membrane fusion. Thus, unlike previously identified structural proteins in muscular dystrophy, dysferlin is likely involved in a novel pathogenic mechanism for this disease. In this study, we have analyzed the expression of dysferlin in skeletal muscle of patients with disruptions in the dystrophin-glycoprotein complex and patients with a clinical diagnosis of LGMD2B or Miyoshi myopathy. We show expression of dysferlin at the sarcolemma in normal muscle and reduced sarcolemmal expression along with accumulation of intracellular staining in dystrophic muscle. Electron microscopy in Miyoshi myopathy biopsies suggests that the cytoplasmic staining could be a result of the abundance of intracellular vesicles. Our results indicate that dysferlin expression is perturbed in LGMD and that both mutations in the dysferlin gene and disruption of the dystrophin-glycoprotein complex can lead to the accumulation of dysferlin within the cytoplasm.

Dysferlin↗
PubMed1999

Disruption of the sarcoglycan-sarcospan complex in vascular smooth muscle: a novel mechanism for cardiomyopathy and muscular dystrophy.

To investigate mechanisms in the pathogenesis of cardiomyopathy associated with mutations of the dystrophin-glycoprotein complex, we analyzed genetically engineered mice deficient for either alpha-sarcoglycan (Sgca) or delta-sarcoglycan (Sgcd). We found that only Sgcd null mice developed cardiomyopathy with focal areas of necrosis as the histological hallmark in cardiac and skeletal muscle. Absence of the sarcoglycan-sarcospan (SG-SSPN) complex in skeletal and cardiac membranes was observed in both animal models. Loss of vascular smooth muscle SG-SSPN complex was only detected in Sgcd null mice and associated with irregularities of the coronary vasculature. Administration of a vascular smooth muscle relaxant prevented onset of myocardial necrosis. Our data indicate that disruption of the SG-SSPN complex in vascular smooth muscle perturbs vascular function, which initiates cardiomyopathy and exacerbates muscular dystrophy.

Animals↗
PubMed1999

Prevalence of Tritrichomonas fetus in a bull population and effect on production in a large cow-calf enterprise.

OBJECTIVE: To determine prevalence of infection with tritrichomonas fetus in a bull population; assess influence of age, breed, and grouping; assess effects on measures of cow performance (pregnancy rate, weaning percentage, weaning weight); and estimate test sensitivity. DESIGN: Epidemiologic study. ANIMALS: 1,383 bulls and records for 28,471 cows bred by these bulls in the immediate past breeding season. PROCEDURE: Bulls in 11 cattle units on a large ranch were tested for T fetus colonization by vigorous preputial scraping and protozoologic culture until no newly infected bulls were identified. Bull infection prevalence within units was calculated and correlated to production measurements reported for each cattle unit. RESULTS: Mean prevalence of T fetus-infected bulls was 11.9% (range, 0 to 35.9%). Significant difference was detected between mean age of infected bulls (5.5 years) and noninfected bulls (3.9 years). Difference in prevalence among breeds was found, although other factors may have influenced this finding. Cow performance measurements (weaning percentage, mean weaning weight, and adjusted mean weaning weight/exposed cow) for cows exposed by breeding to bull groups with the highest prevalence of infection (35.9%) were significantly different from mean values for the entire study population. Test sensitivity for this study (73%) was less than that reported in other studies. CLINICAL IMPLICATIONS: T fetus infection in a natural service beef herd has an adverse impact on several production measures: Severity of impact is related to prevalence of infection in the bull population, where prevalence is bull age and population dependent.

Animals↗
PubMed1999

Implications of prognostic markers in brain tumors.

Summarizing the current evidence regarding the usefulness of the previous markers for predicting patient outcome, the most promising proliferation marker for predicting patient outcome in patients with brain tumors appears to be KI-67/MIB-1. Its potential usefulness appears to be greatest (1) for grade II and III astrocytic and oligodendroglial tumors in adults, where it may potentially predict length of survival; (2) for nonpilocytic gliomas in children, where it may also potentially predict survival; and (3) for benign, completely resected meningiomas, where it may potentially predict tumor recurrence. Although MIB-1 shows potential, we do not believe there is evidence yet definitely to consider MIB-1 labeling index a predictor of prognosis in these tumors due to the lack of published prospective studies validating the preliminary findings of multiple investigators who have performed only single-center retrospective studies. We also believe that the exact use of MIB-1 labeling index as an independent prognostic indicator for any type and grade of tumor may be complex, given the fact that all of these brain tumors have multiple independent prognostic factors contributing to patient outcome, many of which are readily available clinical factors. In the present managed care environment, MIB-1 labeling should probably await demonstration that it significantly contributes to the physician's ability accurately to predict patient outcome. The presence of telomerase RNA or telomerase activity appears to correlate with degree of malignancy in multiple types of brain tumors, including gliomas; however, it currently has no use as an independent prognostic indicator of patient outcome. It may instead be a marker for malignant tumor initiation or progression. p53 and EGFR are molecular markers that show promise as prognostic indicators of recurrence-free and overall survival in patients with GBMs, but further prospective studies are needed to confirm the retrospective findings. Postsurgical evaluation of these markers is potentially helpful in planning follow-up and treatment for these patients, those patients having tumors expressing relatively high levels of these markers requiring closer follow-up and, when possible, more aggressive therapies. Despite intensive investigation into the expression of molecules regulating apoptosis in brain tumors, no evidence presently exists to support their usefulness as markers of patient outcome. This also applies to measurements of the apoptotic rate itself in human brain tumors. Our overall impression, therefore, is that despite our great desire to find the Holy Grail of patient prognosis in the measurement of a single molecular marker with a precise cut-off value, one has not been identified ... yet! If we allow ourselves to think in terms of organismal biology, it is not surprising that the attempt directly to correlate one or even five (MIB-1, telomerase, BCL-2, p53, EGFR) gene products with a phenomenon as complex as a patient's long-term survival is unrealistic. More likely, multiple pieces of clinical information (which we already know significantly impact patient outcome in patients with brain tumors) will be considered in conjunction with new, scientifically proved molecular information as it becomes available, allowing us to predict, ever more accurately, a given patient's clinical course and outcome.

Adult↗
PubMed1998

Sheep liver cytosolic aldehyde dehydrogenase: the structure reveals the basis for the retinal specificity of class 1 aldehyde dehydrogenases.

BACKGROUND: . Enzymes of the aldehyde dehydrogenase family are required for the clearance of potentially toxic aldehydes, and are essential for the production of key metabolic regulators. The cytosolic, or class 1, aldehyde dehydrogenase (ALDH1) of higher vertebrates has an enhanced specificity for all-trans retinal, oxidising it to the powerful differentiation factor all-trans retinoic acid. Thus, ALDH1 is very likely to have a key role in vertebrate development. RESULTS: . The three-dimensional structure of sheep ALDH1 has been determined by X-ray crystallography to 2.35 A resolution. The overall tertiary and quaternary structures are very similar to those of bovine mitochondrial ALDH (ALDH2), but there are important differences in the entrance tunnel for the substrate. In the ALDH1 structure, the sidechain of the general base Glu268 is disordered and the NAD+ cofactor binds in two distinct modes. CONCLUSIONS: . The submicromolar Km of ALDH1 for all-trans retinal, and its 600-fold enhanced affinity for retinal compared to acetaldehyde, are explained by the size and shape of the substrate entrance tunnel in ALDH1. All-trans retinal fits into the active-site pocket of ALDH1, but not into the pocket of ALDH2. Two helices and one surface loop that line the tunnel are likely to have a key role in defining substrate specificity in the wider ALDH family. The relative sizes of the tunnels also suggest why the bulky alcohol aversive drug disulfiram reacts more rapidly with ALDH1 than ALDH2. The disorder of Glu268 and the observation that NAD+ binds in two distinct modes indicate that flexibility is a key facet of the enzyme reaction mechanism.

Aldehyde Dehydrogenase↗
PubMed1998

Progressive muscular dystrophy in alpha-sarcoglycan-deficient mice.

Limb-girdle muscular dystrophy type 2D (LGMD 2D) is an autosomal recessive disorder caused by mutations in the alpha-sarcoglycan gene. To determine how alpha-sarcoglycan deficiency leads to muscle fiber degeneration, we generated and analyzed alpha-sarcoglycan- deficient mice. Sgca-null mice developed progressive muscular dystrophy and, in contrast to other animal models for muscular dystrophy, showed ongoing muscle necrosis with age, a hallmark of the human disease. Sgca-null mice also revealed loss of sarcolemmal integrity, elevated serum levels of muscle enzymes, increased muscle masses, and changes in the generation of absolute force. Molecular analysis of Sgca-null mice demonstrated that the absence of alpha-sarcoglycan resulted in the complete loss of the sarcoglycan complex, sarcospan, and a disruption of alpha-dystroglycan association with membranes. In contrast, no change in the expression of epsilon-sarcoglycan (alpha-sarcoglycan homologue) was observed. Recombinant alpha-sarcoglycan adenovirus injection into Sgca-deficient muscles restored the sarcoglycan complex and sarcospan to the membrane. We propose that the sarcoglycan-sarcospan complex is requisite for stable association of alpha-dystroglycan with the sarcolemma. The Sgca-deficient mice will be a valuable model for elucidating the pathogenesis of sarcoglycan deficient limb-girdle muscular dystrophies and for the development of therapeutic strategies for this disease.

Amino Acid Sequence↗
PubMed1998

Effect of age and dietary restriction on expression of heat shock protein 70 in rat alveolar macrophages.

Dietary restriction (DR) is the only effective experimental manipulation known to retard aging in rodents, and this manipulation has been shown to alter a variety of processes that change with age. However, there is no information on the effect of DR on macrophage Function. In the present study, the effect of aging and DR on the ability of alveolar macrophages (AMs) to express the heat shock gene, hsp70 was studied. AMs were isolated by lavage from the lungs of young (4-6 months) and old (24-26 months) rats fed either ad libitum (AL) or a restricted diet (60% of AL). There was no age-related change in the number of cells recovered from young and old rats fed AL. However, the number of cells recovered from the lungs of the DR rats was reduced, and this decrease was statistically significant in young rats. The expression of heat shock protein 70 (hsp70) was measured by the level of the hsp70 mRNA transcript in total RNA isolated from AMs cultured under two conditions: in suspension and after adherence to plastic. When AMs were incubated at 37 degrees C in suspension, no detectable hsp70 expression was observed; however, hsp70 expression was induced at 37 degrees C when the AMs adhered to the plastic culture dishes. Hsp70 mRNA levels were rapidly induced by heat shock (43 degrees C, 1 h) in AMs cultured both in suspension and on plastic. The induction of hsp70 expression did not change significantly with either age or DR in AMs cultured in suspension. In contrast, the induction of hsp70 mRNA levels by AMs adherent to plastic culture plates decreased approximately 70% with age, and hsp70 induction was greater in AMs isolated from DR rats; this difference was statistically significant in young rats. The induction of hsp70 by heat shock (43 degrees C, 1 h) also decreased with age in the adherent AMs, and DR increased the induction of hsp70 expression three- to fourfold in adherent AMs from both young and old rats.

Aging↗
PubMed1998

Two high-resolution crystal structures of the recombinant N-lobe of human transferrin reveal a structural change implicated in iron release.

The N-lobe of human serum transferrin (hTF/2N) has been expressed in baby hamster kidney cells and crystallized in both orthorhombic (P212121) and tetragonal (P41212) space groups. Both crystal forms diffract to high resolution (1.6 and 1.8 A, respectively) and have been solved by molecular replacement. Subsequent refinement resulted in final models for the structure of hTF/2N that had crystallographic R-factors of 18.1 and 19.7% for the two crystal forms, respectively; these models represent the highest-resolution transferrin structures determined to date. The hTF/2N polypeptide has a folding pattern similar to those of other transferrins, including the presence of a deep cleft that contains the metal-binding site. In contrast to other transferrins, both crystal forms of hTF/2N display disorder at the iron-binding site; model building suggests that this disorder consists of alternative conformations of the synergistically bound carbonate anion, the side chain for Arg-124, and several solvent molecules. Subsequent refinement revealed that conformation A has an occupancy of 0.63-0. 65 and corresponds to the structure of the iron-binding site found in other transferrins. The alternative conformation B has an occupancy of 0.35-0.37; in this structure, the carbonate has rotated 30 degrees relative to the iron and the side chain for Arg-124 has moved to accommodate the new carbonate position. Several water molecules appear to stabilize the carbonate anion in the two conformations. These structures are consistent with the protonation of the carbonate and resulting partial removal of the anion from the metal; these events would occur prior to cleft opening and metal release.

Animals↗
PubMed1998

Regulation of prostaglandin H synthase-2 expression in cerebromicrovascular smooth muscle by serum and epidermal growth factor.

Growth factors may play a role in the formation of prostaglandins (PG) by cerebral blood vessels during development or reaction to injury. In smooth muscle cultures isolated from murine cerebral microvessels PG production was induced with either serum or epidermal growth factor (EGF). Prostaglandin H synthase (PGHS) activity peaked at 6 h after the addition of 10% serum or 50 ng/ml EGF. Increases in expression of PGHS-1 mRNA were small (7- to 10-fold) compared with PGHS-2 (30- to 120-fold), and the induction patterns were different for serum and EGF. An increase in PGHS-2 message was detected by 0.5 h of adding either agent, but peak induction occurred earlier for EGF than for serum, 1 h vs. 3 h, respectively. The response to either stimulus had returned to prestimulation levels by 12 h. The induction of PGHS-2 protein was also transient, but followed a more delayed time course (peak levels at 6 h). Induction of activity, message, and protein by either agent was blocked by 1 microM dexamethasone and attenuated by genistein (100 microM), a nonspecific tyrosine kinase inhibitor. Tyrphostin 47, a more selective EGF receptor tyrosine kinase inhibitor, dose-dependently inhibited EGF-stimulated PGHS activity, completely abolishing PG production at 100 microM. However, this inhibitor had no effect on serum-stimulated PG production. Curiously, 100 microM tyrphostin 47 enhanced EGF-induced PGHS-2 mRNA and protein expression. These data suggest that EGF induces the expression of PGHS-2 in cerebromicrovascular smooth muscle by a mechanism that requires tyrosine kinase activity and that is distinct from serum.

Animals↗