The manganese cation disrupts membrane dynamics along the secretory pathway

The endoplasmic reticulum and Golgi apparatus play key roles in regulating the folding, assembly, and transport of newly synthesized proteins along the secretory pathway. We find that the divalent cation manganese disrupts the Golgi apparatus and endoplasmic reticulum (ER). The Golgi apparatus is fragmented into smaller dispersed structures upon manganese treatment. Golgi residents, such as TGN46, beta1,4-galactosyltransferase, giantin, and GM130, are still segregated and partitioned correctly into smaller stacked fragments in manganese-treated cells. The mesh-like ER network is substantially affected and peripheral ER elements are collapsed. These effects are consistent with manganese-mediated inhibition of motor proteins that link membrane organelles along the secretory pathway to the cytoskeleton. This divalent cation thus represents a new tool for studying protein secretion and membrane dynamics along the secretory pathway.

Physical activity among African American and Latino middle school girls: consistent beliefs, expectations, and experiences across two sites

Physical inactivity is a major public health concern. Low levels of physical activity are reported in many subgroups of women including adolescent girls. More data are needed to better understand factors related to physical activity participation in adolescent girls. Therefore, we explored adolescent girls' reasons for participating and not participating in physical activity. Two independent samples were taken in California and Texas; the total sample included thirty-four African American and Latino girls. Six focus groups were conducted by trained facilitators. Based on independent qualitative analyses, six replicated themes emerged from the focus groups. Fun, social support, and concern with body image facilitated participation in activity. In contrast, negative experiences in physical education classes, concerns about appearance after activity, and lack of opportunity impeded participation in activity. Overall, the girls showed an interest in physical activity and identified activity motivators and barriers. We discuss the implications of our findings for future research.

Genetic manipulation of the rabbit heart via transgenesis

BACKGROUND

Transgenesis using cardiac-specific expression has been valuable in exploring cardiac structure-function relationships. To date, cardiac-selective studies have been confined to the mouse. However, the utility of the mouse is limited in certain, possibly critical, aspects with respect to cardiovascular function.

METHODS AND RESULTS

To establish the potential validity of transgenic methodology for remodeling a larger mammalian heart, we explored cardiac-selective expression in transgenic rabbits. The murine alpha- and beta-cardiac myosin heavy chain gene promoters were used to express a reporter gene, and transgene expression was quantified in cardiac, skeletal, and smooth muscles as well as in nonmuscle tissues. Although neither promoter exactly mimics endogenous patterns of myosin heavy chain expression, both are able to drive high levels of transgene expression in the cardiac compartment. Neither promoter is active in smooth muscle or nonmuscle tissues.

CONCLUSIONS

Directed organ-specific expression is feasible in a larger animal with existing reagents, and cardiac-selective transgenic manipulation is possible in the rabbit.

Muscle activities used by young and old adults when stepping to regain balance during a forward fall

The current study was undertaken to determine if age-related differences in muscle activities might relate to older adults being significantly less able than young adults to recover balance during a forward fall. Fourteen young and twelve older healthy males were released from forward leans of various magnitudes and asked to regain standing balance by taking a single forward step. Myoelectric signals were recorded from 12 lower extremity muscles and processed to compare the muscle activation patterns of young and older adults. Young adults successfully recovered from significantly larger leans than older adults using a single step (32.2 degrees vs. 23.5 degrees ). Muscular latency times, the time between release and activity onset, ranged from 73 to 114 ms with no significant age-related differences in the shortest muscular latency times. The overall response muscular activation patterns were similar for young and older adults. However older adults were slower to deactivate three stance leg muscles and also demonstrated delays in activating the step leg hip flexors and knee extensors prior to and during the swing phase. In the forward fall paradigm studied, age-differences in balance recovery performance do not seem due to slowness in response onset but may relate to differences in muscle activation timing during the stepping movement.

Loss-of-function mutations in the cathepsin C gene result in periodontal disease and palmoplantar keratosis

Papillon-Lefèvre syndrome, or keratosis palmoplantaris with periodontopathia (PLS, MIM 245000), is an autosomal recessive disorder that is mainly ascertained by dentists because of the severe periodontitis that afflicts patients. Both the deciduous and permanent dentitions are affected, resulting in premature tooth loss. Palmoplantar keratosis, varying from mild psoriasiform scaly skin to overt hyperkeratosis, typically develops within the first three years of life. Keratosis also affects other sites such as elbows and knees. Most PLS patients display both periodontitis and hyperkeratosis. Some patients have only palmoplantar keratosis or periodontitis, and in rare individuals the periodontitis is mild and of late onset. The PLS locus has been mapped to chromosome 11q14-q21 (refs 7, 8, 9). Using homozygosity mapping in eight small consanguineous families, we have narrowed the candidate region to a 1.2-cM interval between D11S4082 and D11S931. The gene (CTSC) encoding the lysosomal protease cathepsin C (or dipeptidyl aminopeptidase I) lies within this interval. We defined the genomic structure of CTSC and found mutations in all eight families. In two of these families we used a functional assay to demonstrate an almost total loss of cathepsin C activity in PLS patients and reduced activity in obligate carriers.

Working & breastfeeding: a contemporary workplace dilemma

The benefits of breastfeeding are well known and widely documented. What we are only beginning to understand is the significant impact of returning to work on the experience of breastfeeding. This article describes workplace issues, discusses current literature and examines the range of influences that impact on women's decisions about working and breastfeeding.

Ready for birth--but what about breastfeeding?

This paper examines and discusses a range of influences on the experience of breastfeeding. Primarily, the impact of antenatal education, the experience of labour, birth and postnatal problems on the initiation and duration of breastfeeding are discussed.

Transgenic over-expression of a motor protein at high levels results in severe cardiac pathology

Transgenesis has become a useful tool in effecting a complete or partial remodeling of the cardiac contractile apparatus. Although gene dosage effects were initially a concern, recent data showed that the heart is able to accommodate varying levels of transgenic over-expression without detectable ill effects. The present study was designed to test the limits of the transgenic paradigm in terms of the production of a cardiac phenotype due simply to the over-expression of a contractile protein. To this end, eight lines of mice which express an isoform of the essential myosin light chain 1 that is normally found in the adult ventricle (ELC1v) were generated. Overt phenotype was correlated both with the level of expression/protein replacement and copy number of the transgene. Two of the lines showed essentially complete replacement of the atrial isoform (ELC1a) with ELC1v. However, the phenotypes of the two lines differed dramatically. The line with the lower copy number (37 copies), and moderate over-expression (16 fold) showed no overt pathology while a line with very high copy number (94 copies) and extremely high levels of over-expression (27-50 fold) developed a significant atrial hypertrophy, dilation and cardiomyopathy. These data indicate that very high expression levels of a contractile protein can cause a cardiac pathology that is unrelated to its degree of replacement in the sarcomere and the unique role(s) it may assume in motor protein function.

Living with a cardioverter defibrillator in the community

Internal cardioverter defibrillators are increasingly used for the treatment of life threatening arrhythmias. Patients and their families have described many emotional and psychological consequences of living with these devices. The impact on family members of providing high levels of support can lead to stress-related problems, yet their needs are often underestimated or overlooked.

Prevalence of autoantibodies to ribosomal P proteins in juvenile-onset systemic lupus erythematosus compared with the adult disease

OBJECTIVE

To determine the prevalence of anti-ribosomal P (anti-P) proteins in several groups of patients with juvenile-onset systemic lupus erythematosus (SLE) in comparison with the prevalence in adult SLE.

METHODS

Serum samples were pooled together from 3 cohorts of patients with juvenile-onset SLE in 3 different medical centers and from a miscellaneous group of juvenile-onset SLE patients whose samples were sent by regional physicians. Sera were studied for the presence of anti-P using 2 assays: Western blot with ribosomes as antigen, and an enzyme-linked immunosorbent assay with the COOH-terminal 22 amino acids of the ribosomal P protein in a multiantigenic peptide format as antigen. Sera found positive by both tests were considered positive for anti-P antibodies. Findings from similar studies involving a large cohort of patients with adult-onset SLE from Oklahoma City were used for comparison.

RESULTS

The prevalence of anti-P antibodies in the pooled sample of juvenile-onset SLE sera was 45 of 108, or 42%, while in the adult cohort from Oklahoma City, 20 of 260, or 7.7%, were positive for anti-P (odds ratio [OR] 9.6, P < 10(-8) by Fisher's exact test). In addition, it was shown that 12 of 13 patients with both anti-P and anti-double-stranded DNA (anti-dsDNA) in the juvenile SLE cohort had nephritis, while only 8 of 22 patients without both antibodies were nephritic (OR 21.0, P < 10(-8)). It was also shown that in 9 illustrative cases, the levels of anti-P and anti-dsDNA antibodies usually varied together and in concordance with the clinical activity as measured by the SLE Disease Activity Index (SLEDAI). Finally, anti-P-positive and anti-P-negative patients had a similar prevalence of anti-dsDNA, anti-Ro/SSA, and anti-La/SSB antibodies, but patients with anti-P had a higher prevalence of anti-U1 RNP and anti-Sm (P = 0.041 and P = 0.0385, respectively, by Fisher's exact test).

CONCLUSION

Antibodies to ribosomal P protein are more prevalent in juvenile-onset SLE than in adult-onset SLE. Levels of antibodies to ribosomal P protein vary with the clinical disease activity as measured by the SLEDAI, often in concordance with the levels of anti-dsDNA. The presence of both anti-P and anti-dsDNA antibodies was powerfully associated with nephritis in the cohort of patients for whom comprehensive clinical and serologic data were available.

Perceiving and representing both health and the environment: an exploratory investigation

This article describes an exploratory study that examined the perceptions of both health and environment among men and women in higher and lower status areas in Hamilton, Canada. Situated in the literatures on health perceptions and environmental concerns, it not only describes health and environment perceptions, but also explores their interconnections, arguing that concern for self is more salient than that for any other, including environment, and that this salience is predicated on notions of control and responsibility. The article concludes by speculating on reasons for these findings by suggesting an empirically derived cultural model for representation of health-environment relations and the bases of information processing in this arena.

Caring for patients with an ICD

The internal cardioverter defibrillator corrects life-threatening arrhythmias by providing antitachycardia pacing, pacing for bradycardia, and cardioversion or defibrillation shocks. However, there is little warning that the device may fire, which can cause physical, social and psychological problems for the patient. Nurses caring for ICD patients in the community and in hospital need to know what it is like to live with this device, how it works and the implications for other treatments.

Association of a phosphatidylinositol-specific 3-kinase with a human trans-Golgi network resident protein

The eukaryotic trans-Golgi network (TGN) is a key site for the formation of transport vesicles destined for different intracellular compartments [1]. A key marker for the mammalian TGN is TGN38/46 [2]. This integral membrane glycoprotein cycles between the TGN and the cell surface and is implicated in recruitment of cytosolic factors and regulation of at least one type of vesicle formation at the mammalian TGN [2] [3]. In this study, we have identified a phosphatidylinositol (PtdIns)-specific 3-kinase activity associated with the human orthologue (TGN46), which is sensitive to lipid kinase inhibitors. Treatment of HeLa cells with low levels of these inhibitors reveals subtle morphological changes in TGN46-positive compartments. Our findings suggest a role for PtdIns 3-kinases and presumably for the product, PtdIns 3-phosphate (PtdIns3P), in the formation of secretory transport vesicles by mechanisms conserved in yeast and mammals.