Somatic cell lineage is required for differentiation and not maintenance of germline stem cells in Drosophila testes

Adult stem cells are believed to be maintained by a specialized microenvironment, the niche, which provides short-range signals that either instruct stem cells to self-renew or inhibit execution of preprogrammed differentiation pathways. In Drosophila testes, somatic cyst stem cells (CySCs) and the apical hub form the niche for neighboring germline stem cells (GSCs), with CySCs as the proposed source of instructive self-renewal signals [Leatherman JL, Dinardo S (2010) Nat Cell Biol 12(8):806–811]. In contrast to this model, we show that early germ cells with GSC characteristics can be maintained over time after ablation of CySCs and their cyst cell progeny. Without CySCs and cyst cells, early germ cells away from the hub failed to initiate differentiation. Our results suggest that CySCs do not have a necessary instructive role in specifying GSC self-renewal and that the differentiated progeny of CySCs provide an environment necessary to trigger GSC differentiation. This work highlights the complex interaction between different stem cell populations in the same niche and how the state of one stem cell population can influence the fate of the other.The ability of a stem cell niche to maintain a population of stem cells ensures the continued availability of adult stem cells to replenish and repair specific tissues throughout the lifetime of an organism (1, 2). Failure of a niche to maintain its appropriate stem cell population may lead to degeneration, aging, or an inability to repair tissue damage (3). Conversely, failure of a niche to properly regulate differentiation versus proliferation may contribute to the genesis of cancer in adult stem cell lineages (4). A comprehensive understanding of how the local microenvironment of the stem cell niche functions suggests strategies for expansion of adult stem cell populations in vitro, facilitates design of artificial niches for transplantation, and provides ideas for increasing maintenance and functionality of endogenous adult stem cell populations used for regenerative medicine.The Drosophila testis stem cell niche, a key model for understanding how the microenvironment regulates stem cell behavior (5–7), supports two distinct adult stem cell populations—germline stem cells (GSCs) and cyst stem cells (CySCs)—both of which attach to a cluster of postmitotic somatic cells that form the apical hub (Fig. 1A). GSCs and CySCs normally divide with oriented spindles to produce daughters that remain next to the hub and self-renew and daughters displaced away from the hub that initiate differentiation (8, 9). GSCs give rise to gonialblasts (Gb) and CySCs give rise to postmitotic cyst cells (10), a pair of which encapsulates each Gb to form a cyst. The encapsulated Gb undergoes four rounds of synchronous transit-amplifying (TA) divisions before entering meiosis and terminal differentiation (Fig. 1A).Open in a separate windowFig. 1.Early germ cells can be maintained after ablation of CySCs and cyst cells. (A) Diagram of Drosophila spermatogenesis at the apical tip of the testis. (Red) fusomes; (green) Bam protein expression. (B–G) Immunofluorescence images of c587Gal4; UAS Grim; tubGal80^ts testes stained with anti-FasIII (white, hub), anti-Vasa (red, germ cells), and anti-Tj (green) nuclei of hub, CySCs, and cyst cells). (B) Newly eclosed flies before shift to 30 °C. (Arrowheads) CySCs; (arrows) cyst cells. (C) Flies shifted to 30 °C for 1 d. (D) Flies shifted to 30 °C for 1 d and back to 18 °C for 7 d. (E) Flies shifted to 30 °C for 1 d and back to 18 °C for 7 d. (F) Flies shifted to 30 °C for 1 d and back to 18 °C for 14 d. (G) Flies shifted to 30 °C for 1 d and back to 18 °C for 21 d. (H) Bar graph depicting phenotype distribution at different time points. (Blue bar) Testes with CySCs and/or cyst cells (incomplete ablation); (red bar) testes with early germ cells but lacked CySCs or cyst cells; (green bar) testes lacking early germ cells, CySCs, and cyst cells. No significant difference in phenotype distribution was observed among the 7-, 14-, and 21-d time points. (Scale bar: B–G, 10 μm.)Both the apical hub and the CySCs influence the GSC state. A cytokine-like signal from the hub activates the JAK-STAT signaling pathway in both GSCs and CySCs (11, 12). Although JAK-STAT signaling is required cell autonomously for CySC maintenance, it is not necessary to retain GSCs in their stem cell state. Rather, activity of Stat in the germline is essential for continued attachment of GSCs to the hub and retains GSCs in their niche (13). Several lines of evidence suggest that CySCs provide a niche for maintenance of GSCs (13–15). Consistent with this model, it has been proposed that self-renewal of GSCs is specified by instructive signal(s) from the CySCs, with a likely candidate being TGF-β signaling (13).Here we show that early germ cells can be maintained next to the hub in testes in which CySCs and cyst cells had been permanently ablated. We further show that the progeny of GSC-like cells displaced from the hub failed to initiate the TA program in the absence of CySCs and cyst cells, and instead continued to proliferate as undifferentiated cells. Our findings suggest that CySCs do not play a required instructive role in GSC self-renewal and that cyst cells, the differentiated progeny of CySCs, are required for proper onset of the germline differentiation.     

Ganglion cyst of the foot treated with electroacupuncture: A case report

Objective:

To present the clinical management of a ganglion cyst presenting on the dorsolateral aspect of the foot.

Clinical Features:

A 45-year-old female cyclist complaining of ganglion cyst following training period.

Intervention and Outcome:

Patient was treated with high-frequency electroacupuncture in four consecutive sessions over four weeks, and reported resolution of the cyst following therapeutic intervention.

Conclusions:

Ganglion cysts of the foot are relatively rare connective tissue tumours with variable treatment approaches. Electroacupuncture may be a novel and non-invasive conservative approach for the treatment of ganglion cysts. Further evaluation of the efficacy of such treatment is warranted.     

Evolution of Massachusetts physician attitudes, knowledge, and experience regarding the use of antiretrovirals for HIV prevention

The Center for the AIDS Programme of Research in South Africa (CAPRISA) 004 and Pre-exposure Prophylaxis Initiative (iPrEx) studies demonstrated that topical or oral chemoprophylaxis could decrease HIV transmission. Yet to have an appreciable public health impact, physicians will need to be educated about these new HIV prevention modalities. Massachusetts physicians were recruited via e-mail to complete an online survey of their knowledge and use of HIV prevention interventions. Data were collected before (July-December, 2010) (n=178) and after (December, 2010-April, 2011) (n=115) the release of iPrEx data. Over the two time intervals, knowledge of oral PrEP significantly increased (79% to 92%, p<0.01), whereas knowledge about topical microbicides was already high (89% pre-iPrEx). Post-iPrEx, specialists were more knowledgeable about oral PrEP (p<0.01) and topical microbicides (p<0.001) than generalists. The majority of the respondents would prefer to prescribe topical microbicides (75%) than oral PrEP (25%; p<0.001), primarily because they perceived fewer side effects (95%). Respondents indicated that PrEP should be available if it were a highly effective, daily pill; however, ongoing concerns included: potential drug resistance (93%), decreased funds for other forms of HIV prevention (88%), medication side effects (83%), and limited data regarding PrEP's clinical efficacy (75%). Participants indicated that formal CDC guidelines would have the greatest impact on their willingness to prescribe PrEP (96%). Among Massachusetts physicians sampled, chemoprophylaxis knowledge was high, but current experience was limited. Although topical gel was preferred, responses suggest a willingness to adapt practices pending additional efficacy data and further guidance from normative bodies. Educational programs aimed at incorporating antiretroviral chemoprophylaxis into physicians' HIV prevention practices are warranted.     

The Personal Patient Profile-Prostate decision support for men with localized prostate cancer: A multi-center randomized trial

ObjectiveThe purpose of this trial was to compare usual patient education plus the Internet-based Personal Patient Profile-Prostate, vs. usual education alone, on conflict associated with decision making, plus explore time-to-treatment, and treatment choice.MethodsA randomized, multi-center clinical trial was conducted with measures at baseline, 1-, and 6 months. Men with newly diagnosed localized prostate cancer (CaP) who sought consultation at urology, radiation oncology, or multi-disciplinary clinics in 4 geographically-distinct American cities were recruited. Intervention group participants used the Personal Patient Profile-Prostate, a decision support system comprised of customized text and video coaching regarding potential outcomes, influential factors, and communication with care providers. The primary outcome, patient-reported decisional conflict, was evaluated over time using generalized estimating equations to fit generalized linear models. Additional outcomes, time-to-treatment, treatment choice, and program acceptability/usefulness, were explored.ResultsA total of 494 eligible men were randomized (266 intervention; 228 control). The intervention reduced adjusted decisional conflict over time compared with the control group, for the uncertainty score (estimate ?3.61; (confidence interval, ?7.01, 0.22), and values clarity (estimate ?3.57; confidence interval (?5.85,?1.30). Borderline effect was seen for the total decisional conflict score (estimate ?1.75; confidence interval (?3.61,0.11). Time-to-treatment was comparable between groups, while undecided men in the intervention group chose brachytherapy more often than in the control group. Acceptability and usefulness were highly rated.ConclusionThe Personal Patient Profile-Prostate is the first intervention to significantly reduce decisional conflict in a multi-center trial of American men with newly diagnosed localized CaP. Our findings support efficacy of P3P for addressing decision uncertainty and facilitating patient selection of a CaP treatment that is consistent with the patient values and preferences.     

Neural coupling between the arms and legs during rhythmic locomotor-like cycling movement

Neuronal coupling between the arms and legs allowing coordinated rhythmic movement during locomotion is poorly understood. We used the modulation of cutaneous reflexes to probe this neuronal coupling between the arms and legs using a cycling paradigm. Participants performed rhythmic cycling with arms, legs, or arms and legs together. We hypothesized that any contributions from the arms would be functionally linked to locomotion and would thus be phase-dependent. Reflexes were evoked by electrical stimulation of the superficial peroneal nerve at the ankle, and electromyography (EMG) was recorded from muscles in the arms and legs. The main finding was that the relative contribution from the arms and legs was linked to the functional state of the legs. For example, in tibialis anterior, the largest contribution from arm movement [57% variance accounted for (VAF), P < 0.05] was during the leg power phase, whereas the largest from leg movement (71% VAF, P < 0.05) was during leg cycling recovery. Thus the contribution from the arms was functionally gated throughout the locomotor cycle in a manner that appears to support the action of the legs. Additionally, the effect of arm cycling on reflexes in leg muscles when the legs were not moving was relatively minor; full expression of the effect of rhythmic arm movement was only observed when both the arms and legs were moving. Our findings provide experimental support for the interaction of rhythmic arm and leg movement during human locomotion.     

Utilization of influenza and streptococcal pharyngitis point-of-care testing in the community pharmacy practice setting

Background

One way to reduce the complications and costs of influenza like illness and pharyngitis is to improve access to testing and treatment in early stages of infection. Pharmacy-based screening and treatment of group A streptococcus (GAS) infection and influenza has the potential to improve patient care and population health.

Arm crank ergometry and shoulder pain in persons with spinal cord injury

Dyson-Hudson TA, Sisto SA, Bond Q, Emmons R, Kirshblum SC. Arm crank ergometry and shoulder pain in persons with spinal cord injury.

Objective

To determine whether a primary fitness program utilizing arm crank ergometry would cause increased shoulder pain in persons with spinal cord injury (SCI).

Design

Cohort study.

Setting

Clinical research center.

Participants

People (N=23) with chronic SCI (>1y) who were participating in a weight loss study to compare the effectiveness of diet only (1000kcal/d for 12wk) versus diet with arm crank ergometry (1000kcal/d and arm crank ergometry 3 times a week for 12wk).

Intervention

Arm crank ergometry.

Main Outcome Measure

Changes in shoulder pain intensity using the Wheelchair User’s Shoulder Pain Index (WUSPI).

Results

After adjusting for baseline scores, there was no significant difference between the 2 groups on postintervention WUSPI scores (F_1,20=.85, P=.37, partial η²=.04). The strength of the relationship between group assignment (diet only vs diet and arm crank ergometry) and final WUSPI score was weak, as assessed by a partial η², with group assignment accounting for 4% of the variance on the WUSPI. The adjusted means were lower in the diet and arm crank ergometry group (mean, 7.84) than in the diet only group (mean, 12.22); however, these differences did not appear to be clinically significant.

Conclusions

A primary fitness program using arm crank ergometry does not increase shoulder pain in people with SCI who use wheelchairs. Further investigation with a larger group and what constitutes clinically significant changes on the WUSPI is warranted to confirm our results.