Bioinspired rational design of bi-material 3D printed soft-hard interfaces

Durable interfacing of hard and soft materials is a major design challenge caused by the ensuing stress concentrations. In nature, soft-hard interfaces exhibit remarkable mechanical performance, with failures rarely happening at the interface. Here, we mimic the strategies observed in nature to design efficient soft-hard interfaces. We base our geometrical designs on triply periodic minimal surfaces (i.e., Octo, Diamond, and Gyroid), collagen-like triple helices, and randomly distributed particles. A combination of computational simulations and experimental techniques, including uniaxial tensile and quad-lap shear tests, are used to characterize the mechanical performance of the interfaces. Our analyses suggest that smooth interdigitated connections, compliant gradient transitions, and either decreasing or constraining strain concentrations lead to simultaneously strong and tough interfaces. We generate additional interfaces where the abovementioned toughening mechanisms work synergistically to create soft-hard interfaces with strengths approaching the upper achievable limit and enhancing toughness values by 50%, as compared to the control group.

Echocardiographic global longitudinal strain as a marker of myocardial fibrosis predicts outcomes in aortic stenosis

Background

Left ventricular global longitudinal strain (LV-GLS) by speckle tracking echocardiography (STE) reflects intrinsic myocardial function, influenced by interstitial abnormalities. Cardiovascular magnetic resonance (CMR) detects myocardial fibrosis non-invasively, but it is limited for widespread use. We aim to establish LV-GLS as a marker of replacement myocardial fibrosis on CMR and validate the prognostic value of LV-GLS thresholds associated with fibrosis.

Methods

LV-GLS thresholds of replacement fibrosis were established in the derivation cohort: 151 patients (57±10 years; 58% males) with hypertension who underwent STE to measure LV-GLS and CMR for replacement myocardial fibrosis. Prognostic value of the thresholds was validated in a separate outcome cohort: 261 patients with moderate-severe aortic stenosis (AS; 71±12 years; 58% males; NYHA functional class I-II) and preserved LVEF ≥50%. Primary outcome was a composite of cardiovascular mortality, heart failure hospitalization, myocardial infarction and cerebrovascular events.

Results

In the derivation cohort, LV-GLS demonstrated good discrimination (c-statistics 0.74; 95% confidence interval: 0.66–0.83; P<0.001) and calibration (Hosmer-Lemeshow X2=6.37; P=0.605) for replacement fibrosis. In the outcome cohort, 52 events occurred over 16 [3.1, 42.0] months of follow-up. Patients with LV-GLS >−15.0% (corresponding to 95% specificity to rule-in myocardial fibrosis) had the worst outcomes compared to patients with LV-GLS <−21.0% (corresponding to 95% sensitivity to rule-out myocardial fibrosis) and those between −21.0 and −15.0% (log-rank P<0.001; Figure 1). Furthermore, LV-GLS offered independent prognostic value over clinical variables, AS severity, echocardiographic LVEF and E/e' (hazard ratio 1.18; 95% confidence interval: 1.07 to 1.30; P=0.001).

Conclusions

LV-GLS thresholds associated with replacement myocardial fibrosis is a novel approach to risk-stratify patients with AS and preserved LVEF (Figure 2).

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Medical Research Council Figure 1Figure 2

Gender differences in tuberculosis diagnosis, treatment and outcomes in Victoria, Australia, 2002–2015

BACKGROUND: Gender has a significant impact on tuberculosis (TB) diagnosis and outcomes in many settings worldwide. We explored gender differences in Victoria, Australia, a low-incidence setting.METHODS: Retrospective cohort study: 2002–2015. Gender was included as an independent variable in multivariate statistical analyses assessing TB management.RESULTS: There were 2655 (54.5%) males and 2212 (45.5%) females notified (male:female ratio = 1.2:1). Among cases with pulmonary involvement, males underwent a chest X-ray or CT scan (CXR) sooner (hazard ratio [HR] 1.2, 95%CI 1.04–1.31, P = 0.010), began treatment sooner after presentation (HR 1.2, 95%CI 1.08–1.34, P = 0.001) and were more likely to have a sputum smear sample performed (OR 1.3, 95%CI 1.01–1.55, P = 0.037). Male cases with extra-pulmonary TB sought health care sooner after symptom onset (HR 1.3, 95%CI 1.03–1.58, P = 0.024) and were more likely to have an abnormal CXR (OR 1.9, 95%CI 1.54–2.32, P < 0.001). Males were more likely to die before or during treatment (OR 1.5, 95%CI 1.06–2.11, P = 0.024).CONCLUSIONS: Women experienced small delays in management compared with men, with no obvious detriment to assessment results or treatment outcomes. Differences were consistent with the hypothesis that males manifest more severe disease at presentation, which could be related to a range of biological and social factors.

Mortality among tuberculosis cases in Victoria, 2002-2013: case fatality and factors associated with death

SETTING

The state of Victoria, Australia, is an industrialised setting with low tuberculosis (TB) incidence, universal health care and high levels of migration.

OBJECTIVE

To assess case fatality rates (CFRs) and factors associated with death in a cohort of TB cases notified between 2002 and 2013.

DESIGN

Retrospective cohort study. Cases who died untreated or during treatment were reviewed to determine whether TB was a primary cause of, contributed to or was unrelated to death. Descriptive and multivariate analyses were used to compare demographic, clinical and pathological characteristics.

RESULTS

Of 3956 cases, 198 (5.0%) died of any cause. TB was the primary cause of death in 99 cases (50.3%) and contributed to death in a further 34 cases, giving a TB-related CFR of 3.4%. In multivariate analysis, TB-related mortality reduced over time, and was positively associated with male sex, older age, history of substance use and disseminated or meningeal TB. Factors associated with survival included having a history of past travel to or residence in a high TB risk country, lymph node TB or extra-pulmonary TB manifestations, excluding meningeal, genitourinary, pleural and lymphnode TB.

CONCLUSIONS

TB CFRs in this setting are among the lowest reported globally. TB mortality steadily decreased from 2002 to 2013.

Upper and lower conjunctival fornix depth in healthy white caucasian eyes: a method of objective assessment

PurposeEvaluating anti-scarring therapies require objective assessment of scarring, and knowledge of normal fornix anatomy. Measurement of conjunctival scarring has focused on inferior fornix shortening, although the superior fornix is often overlooked. There are data on normal fornix depth (FD) in South Asians, but there are no studies investigating normal conjunctival FD in white Caucasians. We designed a fornix depth measurer (FDM) for objective measurement of upper and lower conjunctival FD. The purpose of this study was to evaluate intra- and inter-observer variability, and to establish a reference for normal conjunctival FD in an ethnically white Caucasian population.Patients and methodsProspective cross-sectional study evaluating conjunctival FD in 252 clinically normal white Caucasian participants aged 20-80. Paired observers evaluated inter- and intra-observer variability. Data was analyzed using Bland-Altman plots and analysis of variance.ResultsFor white Caucasian subjects, mean upper and lower conjunctival fornix depths were 15.6 mm (95% confidence interval (CI), 12.5-18.8) and 10.9 mm (95% CI, 8.0-13.7), respectively. Females have smaller FDs (upper FD 15.3 mm±1.6 females, 16.2 mm±1.4 males, P<0.001; lower FD 10.6 mm±1.3 females, 11.3 mm±1.4 males, P<0.001). There was a progressive decline in FD with age (upper fornix depth 16.3 mm±1.2 at age 20-29, and 15.0 mm±1.8 at age 80+ (P=0.04)). There was 94-100% intra-observer and inter-observer agreement for upper and lower fornix measurements.ConclusionsUsing a slightly different custom-designed FDM, central conjunctival fornix depth in white Caucasian eyes appears to be similar to data previously reported in South Asian eyes. Fornix depth measurements were repeatable and reproducible.

The impact of off the visual axis retinoscopy on objective central refractive measurement in adult clinical practice: a prospective, randomized clinical study

PURPOSE

The objective of this study was to examine the effect of the off axis retinoscopy on objective central refractive measurement in adult clinical practice.

METHODS

In all, 40 subjects underwent undilated retinoscopy in a randomly selected eye both on and off the visual axis by a single masked examiner. Off axis retinoscopy was defined as retinoscopy performed with the testing eye of the examiner aligned with the contralateral (non-test) eye of the subject resulting in an off axis deviation in the nasal horizontal visual field. Retinoscopy was performed in negative cylinder only and spherocylindrical measurements were converted to power vectors for analysis. Paired t-test was used to assess differences in M, J(0) and J(45) power vectors including differences between mean aided and unaided LogMar acuities.

RESULTS

In all, 14 subjects were myopic (SE≤-0.5 D), 13 subjects were emmetropic (SE between -0.49 and 1.0 D) and 13 subjects were hyperopic (SE >1.0 D). Mean angle of deviation was 5.58° in the nasal horizontal visual field. J(0) showed a significant negative shift in those with myopia (P<0.001) and emmetropia (P=0.049) following off axis retinoscopy. No significant differences in M, J(0) and J(45) were found in the hyperopes. Mean aided LogMar acuities after on and off axis retinoscopy were both significantly better than mean unaided LogMar VA (P<0.001 in both cases).

CONCLUSION

Small degrees of off axis retinoscopy encountered in everyday clinical practice can induce errors in objective central refractive measurement.

A comparison of HRT II and GDx imaging for glaucoma detection in a primary care eye clinic setting

PURPOSE

To evaluate the performance of the HRT II (Heidelberg retinal tomograph) and GDx (glaucoma detection) retinal nerve fibre analyzer in GDx when used in the primary care eye clinic setting for glaucoma screening.

PATIENTS AND METHODS

The study was prospective, cross-sectional, and hospital-based. One-hundred and twelve patients, 59 women and 53 men with a mean age of 57.8 years (range 18-85 years), had consecutive HRT II disc imaging and GDx retinal nerve fiber layer analysis. The Moorfield's regression classification and the 'GDx number' were used to predict the likelihood of glaucoma. A separate clinician, masked to the instrument results determined a definitive diagnosis, based on clinical examination. The extent of agreement between instrument prediction and the clinician diagnosis of glaucoma was examined by generating sensitivity and specificity tables.

RESULTS

The HRT II had a sensitivity of 0.79 (95% CI: 0.60-0.92) and a specificity of 0.70 (95% CI: 0.60-0.78). The positive predictive value of the HRT II was 0.43 (95% CI: 0.29-0.57). Using a GDx number of 50 as 'cutoff' for glaucoma detection, the GDx had a sensitivity of 0.80 (95% CI: 0.59-0.93) and a specificity of 0.72 (95% CI: 0.61-0.80), with a positive predictive value of 0.43 (95% CI: 0.28-0.59).

CONCLUSIONS

For glaucoma detection, neither the HRT II nor the GDx are effective as stand-alone screening devices in the primary care setting.

Acute retention of urine due to prolapsing stoma in a case of anorectal malformation with bladder neck fistula

This case report describes an extremely premature infant who was born with a high anorectal malformation requiring a colostomy soon after birth. He later developed multiple episodes of acute urinary retention complicated by bilateral hydronephrosis and acute renal failure. The cause of the retention was found to be the prolapsing stoma, which was kinking the bladder neck.

Gene delivery to the corneal endothelium

Gene transfer to the corneal endothelium has potential for modulating rejection of corneal grafts. It can also serve as a convenient and useful model for gene therapy of other organs. In this article we review the work carried out in our laboratory using both viral and nonviral vectors to obtain gene expression in the cornea.

Repair of a massive inguinal hernia

Images

Papulonecrotic tuberculide: a forgotten cutaneous manifestation of tuberculosis

A 30-year-old Chinese man presented with a 2-month history of enlarging neck masses and a widespread rash. He had first noticed the swellings 10 years ago when a diagnosis of tuberculosis was made. The lymphadenopathy improved after anti-tuberculous therapy but never completely regressed. Seven years later, a skin eruption developed over his limbs and trunk. He described recurring crops of asymptomatic reddish papules which discharged a yellowish fluid and subsequently healed with scarring and hyperpigmentation. There was no pruritus or tenderness and no pulmonary symptoms.

Clinical examination revealed a non-tender, 10 cm, firm and ovoid mass with overlying erythema in the right anterior triangle of his neck (Figure 1) with several smaller lumps on the other side. There was a widespread eruption on his trunk and limbs, sparing the face, palms, sole and scalp (Figure 2). Recent lesions consisted of 1cm erythematous papules with a scaly collarette (Figure 3). Older lesions had left atrophic scarring and hyperpigmentation. A clinical diagnosis of papulonecrotic tuberculide was made.

An X-ray of the chest was normal. Serum immunoglobulins (IgG, A and M) were moderately elevated. Erythrocyte sedimentation rate and C-reactive protein level were normal. Syphilis serology was negative. A Heaf test was strongly positive (Figure 4).

Fine needle aspirations of the neck mass were negative for microscopic identification of acid-fast bacilli and for malignancy. On the other hand, a lymph node biopsy on the left side revealed fragments of connective tissue showing granulomatous inflammation and non-caseating necrosis. Occasional acid-fast bacilli were seen with a Ziehl-Neelsen stain. Skin biopsies were taken of recent, established and old lesions. The histological features of the established lesion were diagnostic, showing a florid, acute on chronic, perivascular and periappendiceal inflammmatory infiltrate involving both the superficial and deep dermis. There was also evidence of lobular panniculitis with fibrinoid necrosis of medium-sized arterial vessels, venulitis and extensive endothelial cell swelling. Histological features of the other two skin specimens were non-specific. No organisms were identified with special stains.

Anti-tuberculous therapy with rifampicin, isoniazid and pyrazinamide was started and 2 weeks after treatment, the patient reported a complete cessation in the development of new skin lesions. His skin remains in remission after 6 weeks of treatment.

Absence of nonresponse bias in a study of sport-caught Great Lakes fish consumption and conception failure

INTRODUCTION

We have reported that men's lifetime sport-caught Great Lakes fish consumption was associated with lifetime prevalence of conception delay or failure. Those cross-sectional data were based on responses to a postal questionnaire. The present study was conducted to evaluate whether nonresponse bias could explain the cross-sectional findings.

METHODS

We conducted telephone interviews with 230 men and 38 women who did not respond to the original survey, and compared these individuals to the original responders with respect to key demographic, behavioral, and reproductive characteristics.

RESULTS

Nonresponders were approximately 1.5 years older at interview, were more likely to be Caucasian, and reported higher incomes than responders. Among men, nonresponders had fished fewer days in the past year (12% reported no fishing, compared to 4. 3% of responders). Almost one half of nonresponders reported no fish consumption in the past year, compared to one quarter of responders. Nonresponders were more likely than responders to have ever conceived a live-born child, had more children, and were less likely to intend to have additional children in the next 5 years. Among both responders and nonresponders there was an increased prevalence of a period of conception failure among men who reported consuming greater quantities of sport-caught Great Lakes fish.

DISCUSSION

Our study provides support for the cross-sectional analyses presented previously, insofar as nonresponse bias is unlikely to have a major role in the observed association.

Cutaneous nerve hypertrophy

We present a case of cutaneous nerve hypertrophy possibly secondary to scratching or other trauma. The patient was symptomatic and sought surgical treatment, despite no clinical lesion being evident. This type of change has not been previously reported in this clinical setting. There was no clinical evidence of multiple endocrine neoplasia-type 2b (MEN-2b). Awareness of this entity may avoid unnecessary surgery.