C. elegans males optimize mate-preference decisions via sex-specific responses to multimodal sensory cues

For sexually reproducing animals, selecting optimal mates is important for maximizing reproductive fitness. In the nematode C. elegans, populations reproduce largely by hermaphrodite self-fertilization, but the cross-fertilization of hermaphrodites by males also occurs. Males' ability to recognize hermaphrodites involves several sensory cues, but an integrated view of the ways males use these cues in their native context to assess characteristics of potential mates has been elusive. Here, we examine the mate-preference behavior of C. elegans males evoked by natively produced cues. We find that males use a combination of volatile sex pheromones (VSPs), ascaroside sex pheromones, surface-associated cues, and other signals to assess multiple features of potential mates. Specific aspects of mate preference are communicated by distinct signals: developmental stage and sex are signaled by ascaroside pheromones and surface cues, whereas the presence of a self-sperm-depleted hermaphrodite is likely signaled by VSPs. Furthermore, males prefer to interact with virgin over mated, and well-fed over food-deprived, hermaphrodites; these preferences are likely adaptive and are also mediated by ascarosides and other cues. Sex-typical mate-preference behavior depends on the sexual state of the nervous system, such that pan-neuronal genetic masculinization in hermaphrodites generates male-typical social behavior. We also identify an unexpected role for the sex-shared ASH sensory neurons in male attraction to ascaroside sex pheromones. Our findings lead to an integrated view in which the distinct physical properties of various mate-preference cues guide a flexible, stepwise behavioral program by which males assess multiple features of potential mates to optimize mate preference.

Distinct mechanoreceptor pezo-1 isoforms modulate food intake in the nematode Caenorhabditis elegans

Two PIEZO mechanosensitive cation channels, PIEZO1 and PIEZO2, have been identified in mammals, where they are involved in numerous sensory processes. While structurally similar, PIEZO channels are expressed in distinct tissues and exhibit unique properties. How different PIEZOs transduce force, how their transduction mechanism varies, and how their unique properties match the functional needs of the tissues they are expressed in remain all-important unanswered questions. The nematode Caenorhabditis elegans has a single PIEZO ortholog (pezo-1) predicted to have 12 isoforms. These isoforms share many transmembrane domains but differ in those that distinguish PIEZO1 and PIEZO2 in mammals. We used transcriptional and translational reporters to show that putative promoter sequences immediately upstream of the start codon of long pezo-1 isoforms predominantly drive green fluorescent protein (GFP) expression in mesodermally derived tissues (such as muscle and glands). In contrast, sequences upstream of shorter pezo-1 isoforms resulted in GFP expression primarily in neurons. Putative promoters upstream of different isoforms drove GFP expression in different cells of the same organs of the digestive system. The observed unique pattern of complementary expression suggests that different isoforms could possess distinct functions within these organs. We used mutant analysis to show that pharyngeal muscles and glands require long pezo-1 isoforms to respond appropriately to the presence of food. The number of pezo-1 isoforms in C. elegans, their putative differential pattern of expression, and roles in experimentally tractable processes make this an attractive system to investigate the molecular basis for functional differences between members of the PIEZO family of mechanoreceptors.

Response to comment on "Magnetosensitive neurons mediate geomagnetic orientation in Caenorhabditis elegans"

Many animals can orient using the earth’s magnetic field. In a recent study, we performed three distinct behavioral assays providing evidence that the nematode Caenorhabditis elegans orients to earth-strength magnetic fields (Vidal-Gadea et al., 2015). A new study by Landler et al. suggests that C. elegans does not orient to magnetic fields (Landler et al., 2018). They also raise conceptual issues that cast doubt on our study. Here, we explain how they appear to have missed positive results in part by omitting controls and running assays longer than prescribed, so that worms switched their preferred migratory direction within single tests. We also highlight differences in experimental methods and interpretations that may explain our different results and conclusions. Together, these findings provide guidance on how to achieve robust magnetotaxis and reinforce our original finding that C. elegans is a suitable model system to study magnetoreception.

Magnetic orientation in C. elegans relies on the integrity of the villi of the AFD magnetosensory neurons

The magnetic field of the earth provides many organisms with sufficient information to successfully navigate through their environments. While evidence suggests the widespread use of this sensory modality across many taxa, it remains an understudied sensory modality. We have recently showed that the nematode C. elegans orients to earth-strength magnetic fields using the first pair of described magnetosensory neurons, AFDs. The AFD cells are a pair of ciliated sensory neurons crowned by fifty villi known to be implicated in temperature sensation. We investigated the potential importance of these subcellular structures for the performance of magnetic orientation. We show that ciliary integrity and villi number are essential for magnetic orientation. Mutants with impairments AFD cilia or villi structure failed to orient to magnetic fields. Similarly, C. elegans larvae possessing immature AFD neurons with fewer villi were also unable to orient to magnetic fields. Larvae of every stage however retained the ability to orient to thermal gradients. To our knowledge, this is the first behavioral separation of magnetic and thermal orientation in C. elegans. We conclude that magnetic orientation relies on the function of both cilia and villi in the AFD neurons. The role of villi in multiple sensory transduction pathways involved in the sensory transduction of vectorial stimuli further supports the likely role of the villi of the AFD neurons as the site for magnetic field transduction. The genetic and behavioral tractability of C. elegans make it a promising system for uncovering potentially conserved molecular mechanisms by which animals across taxa detect and orient to magnetic fields.

Method for the assessment of neuromuscular integrity and burrowing choice in vermiform animals

BACKGROUND

The study of locomotion in vermiform animals has largely been restricted to animals crawling on agar surfaces. While this has been fruitful in the study of neuronal basis of disease and behavior, the reduced physical challenge posed by these environments has prevented these organisms from being equally successful in the study of neuromuscular diseases. Our burrowing assay allowed us to study the effects of muscular exertion on locomotion and muscle degeneration during disease (Beron et al., 2015), as well as the natural burrowing preference of diverse Caenorhabditis elegans strains (Vidal-Gadea et al., 2015).

NEW METHOD

We describe a simple, rapid, and affordable set of assays to study the burrowing behavior of nematodes and other vermiform organisms which permits the titration of muscular exertion in test animals.

RESULTS

We show that our burrowing assay design is versatile and can be adapted for use in widely different experimental paradigms.

COMPARISON WITH EXISTING METHOD(S)

Previous assays for the study of neuromuscular integrity in nematodes relied on movement through facile and homogeneous environments. The ability of modulating substrate density allows our burrowing assay to be used to separate animal populations where muscular fitness or health are not visible differentiable by standard techniques.

CONCLUSION

The simplicity, versatility, and potential for greatly facilitating the study of previously challenging neuromuscular disorders makes this assay a valuable addition that overcomes many of the limitations inherent to traditional behavioral tests of vermiform locomotion.

Dupuytren's disease presentation, referral pathways and resource utilisation in Europe: regional analysis of a surgeon survey and patient chart review

AIM

We explored the management of Dupuytren's disease (DD) using a surgeon survey and patient chart review.

METHODS

Twelve countries participated: Denmark, Finland, Sweden (Nordic region); Czech Republic, Hungary, Poland (East); France, Germany, the Netherlands, United Kingdom (West); Italy, Spain (Mediterranean). A random sample of orthopaedic/plastic surgeons (N = 687) with 3-30 years' experience was asked about Dupuytren's contracture procedures performed during the previous 12 months. Information ≤ 5 consecutive patients per surgeon was extracted from patient charts (N = 3357).

RESULTS

Overall, 84% of participants were orthopaedic surgeons; 56% of surgeons were hand specialists. Deciding factors for fasciectomy and dermofasciectomy were consistent across regions: metacarpophalangeal (MP) or proximal interphalangeal contracture > 45°, recurrent contracture, and high expectations for success. Deciding factors for percutaneous needle fasciotomy were less consistent across regions, but the leading factor was MP flexion < 20°. Overall, 49% of diagnoses and 55% of referrals were made by a general practitioner (GP), with regional variation: 31-77% for GP diagnoses and 36-81% for GP referrals. There were also differences in admission status (e.g. 9% of Nordic patients and 80% of Eastern patients were treated as inpatients). Most patients were treated in public hospitals and most procedures were covered by public health insurance.

CONCLUSIONS

We found regional variations in surgical practice, patient characteristics and referral patterns. Understanding current diagnosis and treatment patterns, in relation to regional differences in health economics, may improve physicians' diagnosis of DD and guide patients towards appropriate, customised management plans.

Surgical management of Dupuytren's contracture in Europe: regional analysis of a surgeon survey and patient chart review

AIM

We explored regional variations in the surgical management of patients with Dupuytren's contracture (DC) in 12 European countries using a surgeon survey and patient chart review.

METHODS

Twelve countries participated: Denmark, Finland, Sweden (Nordic region); Czech Republic, Hungary, Poland (East); France, Germany, the Netherlands, UK (West); Italy, Spain (Mediterranean). For the survey, a random sample of orthopaedic/plastic surgeons (n = 687) with 3-30 years' experience was asked about DC procedures performed during the previous 12 months. For the chart review (n = 3357), information from up to five consecutive patients was extracted. Descriptive statistics are reported.

RESULTS

Ninety-five per cent of all surgeons used fasciectomy for DC, followed by fasciotomy (70%), dermofasciectomy (38%) and percutaneous needle fasciotomy (35%). Most surgeons were satisfied with fasciectomy over other procedures. Recommended time away from work and duration of physical therapy increased with the invasiveness of the procedure. The intra-operative complication rate was 4.0%; the postoperative complication rate was 34%. Overall, ≥ 97% of the procedures were rated by surgeons as having a positive outcome. Across all regions, 54% of patients had no nodules or contracture after the procedures. Only 2% of patients required retreatment within the first year of surgery. Important inter- and intraregional differences in these aspects of patient management are described.

CONCLUSIONS

Understanding current regional treatment patterns and their relationships to country-specific health systems may facilitate earlier identification of, and intervention for, DD and help to optimise the overall treatment for patients with this chronic condition.

Predictors of bone mass by peripheral quantitative computed tomography in early adolescent girls

This cross-sectional study used peripheral quantitative computed tomography (pQCT) to evaluate the influences of age, body size, puberty, calcium intake, and physical activity on bone acquisition in healthy early adolescent girls. The pQCT technique provides analyses of volumetric bone mineral density (vBMD) (mg/cm(3)) for total as well as cortical and trabecular bone compartments and bone strength expressed as polar strength strain index (mm(2)). Bone mass of the nondominant distal and midshaft tibia by pQCT and lumbar spine and hip by dual X-ray absorptiometry (DXA) were measured in 84 girls ages 11-14 yr. Pubertal stage, menarche status, anthropometrics, and 3-d food intake and physical activity records were collected. Total and cortical bone mineral content and vBMD measurements by pQCT were significantly related to lumbar spine and femoral neck BMD measurements by DXA. We did not note any significant determinants or predictors for trabecular bone mass. Body weight was the most important predictor and determinant of total and cortical bone density and strength in healthy adolescent girls. Menarche, calcium intake, height, body mass index, and weight-bearing physical activity level age were also identified as minor but significant predictors and determinants of bone density and strength. Bone measurements by the pQCT technique provide information on bone acquisition, architecture, and strength during rapid periods of growth and development. Broader cross-sectional studies using the pQCT technique to evaluate the influence of age, gender, ethnicity, puberty, body size, and lifestyle factors on bone acquisition and strength are needed.

Cyclosporine as maintenance therapy in patients with severe psoriasis

BACKGROUND

Low-dose cyclosporine therapy for severe plaque psoriasis is effective. Most side effects can be controlled by patient monitoring, with appropriate dose adjustment or pharmacologic intervention, or both, if indicated. Prevention or reversibility of laboratory and chemical abnormalities may be achieved by discontinuation of therapy after the induction of clearing. However, relapse occurs rapidly on discontinuation. Maintenance therapy with cyclosporine after induction has not been fully evaluated.

OBJECTIVE

Our purpose was to compare a regimen of 3.0 mg/kg per day of oral cyclosporine with placebo in maintaining remission or improvement in patients with psoriasis.

METHODS

After a 16-week unblinded induction phase in which 181 patients received cyclosporine, 5.0 mg/kg per day (an increase up to 6.0 mg/kg per day and a decrease to 3.0 mg/kg per day were allowed, if required, to achieve efficacy or tolerability, respectively), those patients showing a 70% decrease or more in involved body surface area (BSA) entered the 24-week maintenance phase and were randomly assigned to either placebo, cyclosporine, 1.5 mg/kg per day, or cyclosporine, 3.0 mg/kg per day. Patients were considered to have had a relapse when BSA returned to 50% or more of the prestudy baseline value. Clinical efficacy, adverse effects, and laboratory values were monitored regularly throughout both study phases.

RESULTS

During induction, cyclosporine at approximately 5.0 mg/kg per day produced a reduction in BSA of 70% or more in 86% of the patients. During maintenance, the median time to relapse was 6 weeks in both the placebo and cyclosporine 1.5 mg/kg per day groups, but was longer than the 24-week maintenance period in the 3.0 mg/kg per day group (p < 0.001 vs placebo). By the end of the maintenance period, 42% of the patients in the 3.0 mg/kg per day cyclosporine group had a relapse compared with 84% in the placebo group. Changes in laboratory values associated with the higher induction dosage generally exhibited partial or complete return toward mean prestudy baseline values during the maintenance phase, with the greatest degree of normalization in the placebo group.

CONCLUSION

Cyclosporine, 3.0 mg/kg per day, adequately and safely maintained 58% of patients with psoriasis for a 6-month period after clearing of their psoriasis with doses of approximately 5.0 mg/kg per day.

Long-term low-dose cyclosporine therapy for severe psoriasis: effects on renal function and structure

BACKGROUND

The effectiveness of cyclosporine in the treatment of severe psoriasis is well known.

OBJECTIVE

We evaluated the efficacy and toxicity of systemic cyclosporine in patients with severe psoriasis, observing short-term (12 weeks) and long-term (3 to 5 years) effects.

METHODS

To further elucidate efficacy and safety, 42 patients with severe psoriasis were treated initially with cyclosporine 5 to 6 mg/kg per day for 12 weeks. A subset of 14 patients continued maintenance treatment for 3.5 years to study the long-term effects of cyclosporine on renal function and structure. Renal biopsies were performed after 2.5 years and 3.5 years of treatment. Renal histologic findings were correlated with renal function.

RESULTS

By weeks 8 and 12, 64% (n = 27) and 86% (n = 36) of patients, respectively, were rated clear or almost clear of the psoriasis. However, a subpopulation of 15 patients did not respond to 5 mg/kg daily but improved when the dose was increased to 6 mg/kg daily. Clearance or near clearance was achieved in 67% of this subpopulation after 4 weeks. For the 29 patients whose glomerular filtration rate (GFR) was measured, mean GFR fell by 7% from baseline to week 4 (p < 0.05). This change was reversible when dosage was reduced by 1 mg/kg per day in each of these patients. Patients older than 45 years of age experienced significant elevation of mean diastolic blood pressure and had reduced GFR and increased serum creatinine. After 2.5 years, of the 14 patients who continued maintenance treatment, two had biopsy specimens that showed moderate interstitial fibrosis and tubular atrophy. The remainder showed only minimal to mild structural damage. After 3.5 years of cyclosporine treatment, repeat renal biopsy specimens revealed slight increases in structural changes in nine subjects. These changes correlated with increasing age and drug-induced hypertension.

CONCLUSION

We conclude that 5 mg/kg of cyclosporine daily is usually an effective initial dose for psoriasis. Patients who do not respond will often benefit from elevation of the dose to 6 mg/kg daily. Older patients experience cyclosporine-induced hypertension and changes in renal function and structure more frequently than do younger patients.

Reconstruction of the axilla with a posterior arm fasciocutaneous flap

We present our experience with the use of the posterior arm fasciocutaneous flap in the reconstruction of 22 axillae in 17 patients. These patients all suffered from long-standing, severe hidradenitis suppurativa and this flap was used to reconstruct the axilla after surgical excision of the whole hair-bearing area of the axilla and the underlying axillary disease. In most cases, excision included all of the axillary contents up to the axillary vessels but excluded the apex of the axilla. Nineteen axillae were reconstructed with a pedicled flap. Three axillae were reconstructed more recently with an island flap. All reconstructions were achieved without flap complications.