Publications

UNLABELLED

Hepatic stellate cells play an essential role in the liver's injury response. Although stellate cells are defined by the presence of cytoplasmic protrusions, the function of these characteristic structures has been obscure. We hypothesized that stellate cell protrusions act by coupling injury-associated stimuli to chemotaxis. To test this hypothesis, we developed an assay for directly visualizing the response of living stellate cells in early primary culture to local stimulation of the tips of protrusions with platelet-derived growth factor-BB (PDGF). Stellate cells exhibited elongate protrusions containing actin, myosin, and tubulin. PDGF, but not cytochrome C, localized at a protrusion tip induced a coordinated series of morphological events--cell spreading at the tip, movement of the cell body toward the PDGF, and retraction of trailing protrusions--that resulted in chemotaxis. Soluble PDGF and AG 1296, a receptor tyrosine kinase inhibitor, both reduced stellate cell chemotaxis. PDGF-induced chemotaxis was associated with an early and transient increase in myosin phosphorylation within the spreading lamella. We observed that blebbistatin, a myosin II inhibitor, completely and reversibly blocked protrusion-mediated lamella formation and chemotaxis. Moreover, blockade of MRLC phosphorylation with the myosin light chain kinase inhibitor, ML-7, or the rho kinase inhibitor, Y-27632, blocked lamella formation, myosin phosphorylation within the protrusion, and chemotaxis.

CONCLUSION

These results support a model in which protrusions permit stellate cells to promptly detect PDGF distant from their cell bodies and transduce this signal into mechanical forces that propel the cell toward the site of injury.

BACKGROUND AND OBJECTIVES

Access to abortion services in the United States is declining. While family physicians are well suited to provide this care, limited training in abortion occurs in family medicine residency programs. This study was designed to describe the structure of currently available training and the experience of residents participating in these programs.

METHODS

E-mail questionnaires were sent to key faculty members and third-year residents in nine programs that have required abortion training. These faculty members and a sample of residents also completed semi-structured interviews.

RESULTS

Residency programs varied in the amount of time dedicated to the procedural aspects of abortion training, ranging from 2 to 8 days, and also in non-procedural aspects of training such as values clarification and didactics. Themes that emerged from interviews with residents included the benefit of training with respect to technical skills and continuity of care. In addition, residents valued discussion of the emotional aspects of abortion care and issues relating to performing abortions after graduation from residency.

CONCLUSIONS

While the details of the curricula vary, residents in programs with required abortion training generally felt positively about their experiences and felt that abortion was an appropriate procedure for family physicians to provide. Residents emphasized the importance of both non-procedural and technical aspects of training.

When, as a condition of the Master Settlement Agreement (MSA) in 1998, US tobacco companies disbanded the Council for Tobacco Research and the Center for Indoor Air Research, they lost a vital connection to scientists in academia and the private sector. The aim of this paper was to investigate two new research projects funded by US tobacco companies by analysis of internal tobacco industry documents now available at the University of California San Francisco (San Francisco, California, USA) Legacy tobacco documents library, other websites and the open scientific literature. Since the MSA, individual US tobacco companies have replaced their industry-wide collaborative granting organisations with new, individual research programmes. Philip Morris has funded a directed research project through the non-profit Life Sciences Research Office, and British American Tobacco and its US subsidiary Brown and Williamson have funded the non-profit Institute for Science and Health. Both of these organisations have downplayed or concealed their true level of involvement with the tobacco industry. Both organisations have key members with significant and long-standing financial relationships with the tobacco industry. Regulatory officials and policy makers need to be aware that the studies these groups publish may not be as independent as they seem.

To meet the challenges of diagnosis and management of infectious diseases, clinical pathology residents must receive comprehensive training in microbiology, learn to think critically, develop problem-solving skills, and take active roles as laboratory consultants. Residents well trained in clinical microbiology become capable laboratory professionals, developing cost-effective testing strategies, decreasing risk for medical errors, and improving patient care. Newer methods for diagnosing infectious disease, such as real-time polymerase chain reaction, microarrays for pathogen detection, and rapid assays for antigen or antibody detection, have become standard. Knowledge of infectious disease principles, drug therapeutic options, and drug resistance is also important. Suggestions for training and for assessing resident competency in clinical microbiology are presented.

Presumptive treatment of malaria results in significant overuse of antimalarials. Malaria rapid diagnostic tests (RDTs) may offer a reliable alternative for case management, but the optimal RDT strategy is uncertain. We compared the diagnostic accuracy of histidine-rich protein 2 (HRP2)- and plasmodium lactate dehydrogenase (pLDH)-based RDTs, using expert microscopy as the gold standard, in a longitudinal study of 918 fever episodes over an 8-month period in a cohort of children in Kampala, Uganda. Sensitivity was 92% for HRP2 and 85% for pLDH, with differences primarily due to better detection with HRP2 at low parasite densities. Specificity was 93% for HRP2 and 100% for pLDH, with differences primarily due to rapid clearance of pLDH antigenemia after treatment of a previous malaria episode. RDTs may provide an effective strategy for improving rational delivery of antimalarial therapy; in Kampala, either test could dramatically decrease inappropriate presumptive treatments.

Ubiquitously expressed focal adhesion kinase (FAK), linked to multiple intracellular signaling pathways, has previously been shown to control cell motility, invasion, proliferation, and survival. Using mice with a keratinocyte-restricted deletion of fak (FAK(K5 KO)), we report here a novel role for FAK: maintenance of adult epidermal permeability barrier homeostasis. Abundant lacunae of unprocessed lipids in stratum corneum (SC) of FAK(K5 KO) mice and delayed barrier recovery pointed to malfunction of pH-dependent enzymes active in extracellular space of SC. Measuring the SC pH gradient showed significantly more neutral pH values in FAK(K5 KO) mice, suggesting the importance of FAK for acidification. Moreover, normal functions were restored when FAK(K5 KO) mice were exposed to a surface pH typical of mouse SC (pH = 5.5). Baseline levels and response to barrier disruption of secretory phospholipase A2 isoforms, enzymes that mediate generation of free fatty acids in epidermis, appeared similar in both FAK(K5 KO) and control littermates. We found that the critical SC acidification regulator Na(+)/H(+) exchanger 1 failed to localize to the plasma membrane in FAK-deficient keratinocytes both in vivo and in vitro. Thus, for plasma membrane localization in terminally differentiated keratinocytes, Na(+)/H(+) exchanger 1 requires an intact actin cytoskeleton, which is impaired in FAK-deficient cells.