Progress and Opportunities for Machine Learning in Materials and Processes of Additive Manufacturing

In recent years, there has been a widespread adoption of machine learning (ML) technologies to unravel intricate relationships among diverse parameters in various additive manufacturing (AM) techniques. These ML models excel at recognizing complex patterns from extensive, well-curated datasets, thereby unveiling latent knowledge crucial for informed decision-making during the AM process. The collaborative synergy between ML and AM holds the potential to revolutionize the design and production of AM-printed parts. By leveraging the copious data generated in AM processes, ML algorithms can significantly enhance design optimization. This is achieved by employing forward problem analysis in tandem with iterative optimization techniques or generative artificial intelligence tools. The approach involves reverse-engineering from desired outcomes to yield valuable insights, ultimately streamlining the AM design process. This review paper delves into the challenges and opportunities emerging at the intersection of these two dynamic fields. It provides a comprehensive analysis of the publication landscape for ML-related research in the field of AM, explores common ML applications in AM research (such as quality control, process optimization, design optimization, microstructure analysis, and material formulation) and concludes by presenting an outlook that underscores the utilization of advanced ML models, the development of emerging sensors, and ML applications in emerging AM-related fields. Notably, ML has garnered increased attention in AM due to its superior performance across various AM-related applications. We envision that the integration of ML into AM processes will significantly enhance 3D printing capabilities across diverse AM-related research areas. This article is protected by copyright. All rights reserved.

Survey of Patient Knowledge and Awareness of "Sick Day Rules" in Rheumatology Patients on Long Term Glucocorticoid Therapy

Aims Rheumatic disease (RMD) patients treated with long-term glucocorticoids (GC) are at risk of developing tertiary adrenal insufficiency. With this survey we aimed to assess the knowledge of RMD patients taking long-term glucocorticoid therapy regarding risk of adrenal insufficiency and understanding of the "steroid sick day rules". Methods RMD patients taking ≥2.5 mg prednisolone daily for ≥3 months were recruited from the Rheumatology outpatient department in Beaumont Hospital, Dublin. Patient knowledge and previous counselling of steroid sick day rules was determined using an 8-point questionnaire carried out face-to-face or via phone call. Results 51 RMD patients on GC therapy were recruited. 3/51 (5.9%) of patients reported that they had been counselled on the Sick Day Rules. 2/51 (3.9%) carried a steroid emergency card or MedicAlert bracelet. Few patients would increase their steroid dose appropriately in response to infection, vomiting or peri-procedure [14/51 (27.5%); 9/51 (17.7%) and 5/51 (7.2%), respectively]. Conclusion We demonstrate a significant deficit of patient knowledge around the precautions for long-term GC use in rheumatic diseases. We suspect that our results may be generalisable to many other RMD units. We are currently reviewing our procedures around healthcare professional and patient education, issuing of information leaflets, emergency cards or MedicAlert bracelets etc. to at risk patients.

Improving printability of hydrogel-based bio-inks for thermal inkjet bioprinting applications via saponification and heat treatment processes

Material jetting bioprinting is a highly promising three-dimensional (3D) bioprinting technique that facilitates drop-on-demand (DOD) deposition of biomaterials and cells at pre-defined positions with high precision and resolution. A major challenge that hinders the prevalent use of the material jetting bioprinting technique is due to its limited range of printable hydrogel-based bio-inks. As a proof-of-concept, further modifications were made to gelatin methacrylate (GelMA), a gold-standard bio-ink, to improve its printability in a thermal inkjet bioprinter (HP Inc. D300e Digital Dispenser). A two-step modification process comprising saponification and heat treatment was performed; the GelMA bio-ink was first modified via a saponification process under highly alkali conditions to obtain saponified GelMA (SP-GelMA), followed by heat treatment via an autoclaving process to obtain heat-treated SP-GelMA (HSP-GelMA). The bio-ink modification process was optimized by evaluating the material properties of the GelMA bio-inks via rheological characterization, the bio-ink crosslinking test, nuclear magnetic resonance (NMR) spectroscopy and the material swelling ratio after different numbers of heat treatment cycles (0, 1, 2 and 3 cycles). Lastly, size-exclusion chromatography with multi-angle light scattering (SEC-MALS) was performed to determine the effect of heat treatment on the molecular weight of the bio-inks. In this work, the 4% H2SP-GelMA bio-inks (after 2 heat treatment cycles) demonstrated good printability and biocompatibility (in terms of cell viability and proliferation profile). Furthermore, thermal inkjet bioprinting of the modified hydrogel-based bio-ink (a two-step modification process comprising saponification and heat treatment) via direct/indirect cell patterning is a facile approach for potential fundamental cell-cell and cell-material interaction studies.

Controlling Droplet Impact Velocity and Droplet Volume: Key Factors to Achieving High Cell Viability in Sub-Nanoliter Droplet-based Bioprinting

Three-dimensional (3D) bioprinting systems serve as advanced manufacturing platform for the precise deposition of cells and biomaterials at pre-defined positions. Among the various bioprinting techniques, the drop-on-demand jetting approach facilitates deposition of pico/nanoliter droplets of cells and materials for study of cell-cell and cell-matrix interactions. Despite advances in the bioprinting systems, there is a poor understanding of how the viability of primary human cells within sub-nanoliter droplets is affected during the printing process. In this work, a thermal inkjet system is utilized to dispense sub-nanoliter cell-laden droplets, and two key factors – droplet impact velocity and droplet volume – are identified to have significant effect on the viability and proliferation of printed cells. An increase in the cell concentration results in slower impact velocity, which leads to higher viability of the printed cells and improves the printing outcome by mitigating droplet splashing. Furthermore, a minimum droplet volume of 20 nL per spot helps to mitigate evaporation-induced cell damage and maintain high viability of the printed cells within a printing duration of 2 min. Hence, controlling the droplet impact velocity and droplet volume in sub-nanoliter bioprinting is critical for viability and proliferation of printed human primary cells.

Fabrication and Characterization of 3D Bioprinted Triple-layered Human Alveolar Lung Models

The global prevalence of respiratory diseases caused by infectious pathogens has resulted in an increased demand for realistic in-vitro alveolar lung models to serve as suitable disease models. This demand has resulted in the fabrication of numerous two-dimensional (2D) and three-dimensional (3D) in-vitro alveolar lung models. The ability to fabricate these 3D in-vitro alveolar lung models in an automated manner with high repeatability and reliability is important for potential scalable production. In this study, we reported the fabrication of human triple-layered alveolar lung models comprising of human lung epithelial cells, human endothelial cells, and human lung fibroblasts using the drop-on-demand (DOD) 3D bioprinting technique. The polyvinylpyrrolidone-based bio-inks and the use of a 300 mm nozzle diameter improved the repeatability of the bioprinting process by achieving consistent cell output over time using different human alveolar lung cells. The 3D bioprinted human triple-layered alveolar lung models were able to maintain cell viability with relative similar proliferation profile over time as compared to non-printed cells. This DOD 3D bioprinting platform offers an attractive tool for highly repeatable and scalable fabrication of 3D in-vitro human alveolar lung models.

Minimally Invasive versus Conventional Open Surgery for Fixation of Spinal Fracture in Ankylosed Spine

Introduction:

This was a retrospective study aimed to investigate the perioperative outcomes of long construct minimally invasive spinal stabilisation (MISt) using percutaneous pedicle screws (PPS) versus conventional open spinal surgery in the treatment of spinal fracture in ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH).

Material and Methods:

Twenty-one patients with AS and DISH who were surgically treated between 2009 and 2017 were recruited. Outcomes of interest included operative time, intra-operative blood loss, complications, duration of hospital stay and fracture union rate.

Results:

Mean age was 69.2 ± 9.9 years. Seven patients had AS and 14 patients had DISH. 17 patients sustained AO type B3 fracture and 4 patients had type B1 fracture. Spinal trauma among these patients mostly involved thoracic spine (61.9%), followed by lumbar (28.6%) and cervical spine (9.5%). MISt using PPS was performed in 14 patients (66.7%) whereas open surgery in 7 patients (33.3%). Mean number of instrumentation level was 7.9 ± 1.6. Mean operative time in MISt and open group was 179.3 ± 42.3 minutes and 253.6 ± 98.7 minutes, respectively (p=0.028). Mean intra-operative blood loss in MISt and open group was 185.7 ± 86.4ml and 885.7 ± 338.8ml, respectively (p<0.001). Complications and union rate were comparable between both groups.

Conclusion:

MISt using PPS lowers the operative time and reduces intra-operative blood loss in vertebral fractures in ankylosed disorders. However, it does not reduce the perioperative complication rate due to the premorbid status of the patients. There was no significant difference in the union rate between MISt and open surgery.

Bioprinting of Collagen: Considerations, Potentials, and Applications

Collagen is the most abundant extracellular matrix protein that is widely used in tissue engineering (TE). There is little research done on printing pure collagen. To understand the bottlenecks in printing pure collagen, it is imperative to understand collagen from a bottom-up approach. Here it is aimed to provide a comprehensive overview of collagen printing, where collagen assembly in vivo and the various sources of collagen available for TE application are first understood. Next, the current printing technologies and strategy for printing collagen-based materials are highlighted. Considerations and key challenges faced in collagen printing are identified. Finally, the key research areas that would enhance the functionality of printed collagen are presented.

Vat polymerization-based bioprinting-process, materials, applications and regulatory challenges

Over the years, the field of bioprinting has attracted attention for its highly automated fabrication system that enables the precise patterning of living cells and biomaterials at pre-defined positions for enhanced cell-matrix and cell-cell interactions. Notably, vat polymerization (VP)-based bioprinting is an emerging bioprinting technique for various tissue engineering applications due to its high fabrication accuracy. Particularly, different photo-initiators (PIs) are utilized during the bioprinting process to facilitate the crosslinking mechanism for fabrication of high-resolution complex tissue constructs. The advancements in VP-based printing have led to a paradigm shift in fabrication of tissue constructs from cell-seeding of tissue scaffolds (non-biocompatible fabrication process) to direct bioprinting of cell-laden tissue constructs (biocompatible fabrication process). This paper, presenting a first-time comprehensive review of the VP-based bioprinting process, provides an in-depth analysis and comparison of the various biocompatible PIs and highlights the important considerations and bioprinting requirements. This review paper reports a detailed analysis of its printing process and the influence of light-based curing modality and PIs on living cells. Lastly, this review also highlights the significance of VP-based bioprinting, the regulatory challenges and presents future directions to transform the VP-based printing technology into imperative tools in the field of tissue engineering and regenerative medicine. The readers will be informed on the current limitations and achievements of the VP-based bioprinting techniques. Notably, the readers will realize the importance and value of highly-automated platforms for tissue engineering applications and be able to develop objective viewpoints towards this field.

The future of skin toxicology testing - Three-dimensional bioprinting meets microfluidics

Over the years, the field of toxicology testing has evolved tremendously from the use of animal models to the adaptation of in vitro testing models. In this perspective article, we aim to bridge the gap between the regulatory authorities who performed the testing and approval of new chemicals and the scientists who designed and fabricated these in vitro testing models. An in-depth discussion of existing toxicology testing guidelines for skin tissue models (definition, testing models, principle, and limitations) is first presented to have a good understanding of the stringent requirements that are necessary during the testing process. Next, the ideal requirements of toxicology testing platform (in terms of fabrication, testing, and screening process) are then discussed. We envisioned that the integration of three-dimensional bioprinting within miniaturized microfluidics platform would bring about a paradigm shift in the field of toxicology testing; providing standardization in the fabrication process, accurate, and rapid deposition of test chemicals, real-time monitoring, and high throughput screening for more efficient skin toxicology testing.

Healing of Chronic Wounds: An Update of Recent Developments and Future Possibilities

Chronic wounds are the result of disruptions in the body's usual process of healing. They are not only a source of significant pain and discomfort but also, more importantly, an unguarded port of entry for pathogens into the body. While our current understanding of this phenomenon is far from complete, findings in physiological patterns and advancements in wound healing technologies have helped develop wound management and healing solutions to this long-standing medical challenge. This review presents an overview of known wound healing mechanics, abnormalities that lead to chronic wounds, and a summary of established and new wound healing technologies. Various approaches to heal wounds are discussed, from dermal replacements to advanced biomaterial-based treatments, from cell-, synthetic-, and composite-based approaches to preclinical approaches, which make developing such products possible. While tested breakthrough products are described, the authors focused more on recently developed innovations, which are at varying stages of maturity. The review concludes with a note on future perspectives and opinions on where the field and industry are headed and where they should be. Impact Statement Wound healing is an important area of research and clinical practice, and has captured the attention of tissue engineers since the nascent beginnings of the discipline. Tissue-engineered skin was the first FDA-approved product, achieved in 1996. Despite this success, and the passage of time, healing wounds, particularly chronic wounds, remains a vexing challenge. This comprehensive review article will provide readers with a synopsis of current issues, research approaches, animal models, technologies, and products that span the continuum from early development to clinical studies, in the hope of fueling new interests and ideas to overcome this long-standing medical challenge.

Layer-by-layer ultraviolet assisted extrusion-based (UAE) bioprinting of hydrogel constructs with high aspect ratio for soft tissue engineering applications

One of the major challenges in the field of soft tissue engineering using bioprinting is fabricating complex tissue constructs with desired structure integrity and mechanical property. To accomplish such requirements, most of the reported works incorporated reinforcement materials such as poly(ϵ-caprolactone) (PCL) polymer within the 3D bioprinted constructs. Although this approach has made some progress in constructing soft tissue-engineered scaffolds, the mechanical compliance mismatch and long degradation period are not ideal for soft tissue engineering. Herein, we present a facile bioprinting strategy that combines the rapid extrusion-based bioprinting technique with an in-built ultraviolet (UV) curing system to facilitate the layer-by-layer UV curing of bioprinted photo-curable GelMA-based hydrogels to achieve soft yet stable cell-laden constructs with high aspect ratio for soft tissue engineering. GelMA is supplemented with a viscosity enhancer (gellan gum) to improve the bio-ink printability and shape fidelity while maintaining the biocompatibility before crosslinking via a layer-by-layer UV curing process. This approach could eventually fabricate soft tissue constructs with high aspect ratio (length to diameter) of ≥ 5. The effects of UV source on printing resolution and cell viability were also studied. As a proof-of-concept, small building units (3D lattice and tubular constructs) with high aspect ratio are fabricated. Furthermore, we have also demonstrated the ability to perform multi-material printing of tissue constructs with high aspect ratio along both the longitudinal and transverse directions for potential applications in tissue engineering of soft tissues. This layer-by-layer ultraviolet assisted extrusion-based (UAE) Bioprinting may provide a novel strategy to develop soft tissue constructs with desirable structure integrity.

Evaluating the concurrent validity of body mass index (BMI) in the identification of malnutrition in older hospital inpatients

BACKGROUND

Nutrition screening and assessment tools often include body mass index (BMI) as a component in identifying malnutrition risk. However, rising obesity levels will impact on the relevancy and applicability of BMI cut-off points which may require re-evaluation. This study aimed to explore the relationship between commonly applied BMI cut-offs and diagnosed malnutrition.

METHODS

Data (age, gender, BMI and Subjective Global Assessment (SGA) ratings) were analysed for 1152 inpatients aged ≥65 years across annual malnutrition audits (2011-2015). The receiver operation characteristic (ROC) curve analysed the optimal BMI cut-off for malnutrition and concurrent validity of commonly applied BMI cut-offs in nutritional screening and assessment tools.

RESULTS

Malnutrition prevalence was 36.0% (n = 372) using SGA criteria (not malnourished, moderate or severe malnutrition). Median age was 78.7 (IQR 72-85) years, median BMI 25.4 (IQR 21.8-29.7) kg/m²; 52.1% male and 51.2% overweight/obese. ROC analysis identified an optimal BMI cut-off of <26 kg/m², 80.8% sensitivity and 61.5% specificity (AUC 0.802, 95% CI 0.773, 0.830; p < 0.0001). Commonly applied BMI cut-offs (between 18.5 and 23 kg/m²) failed to meet the alpha-priori requirement of 80% sensitivity and 60% specificity. However, BMI <23 kg/m² had the highest agreement (κ = 0.458) with malnutrition diagnosed using the SGA.

CONCLUSIONS

Both malnutrition and overweight/obesity are common in older inpatients. Continuing increases in the prevalence of overweight and obesity will impact on the sensitivity of BMI as a screening component for malnutrition risk. The current study suggests tools developed over a decade ago may need to be revisited in future.

Applying macromolecular crowding to 3D bioprinting: fabrication of 3D hierarchical porous collagen-based hydrogel constructs

3D bioprinting of hierarchical porous structures for tissue engineering.

Does intentional weight loss improve daytime sleepiness? A systematic review and meta-analysis

Obesity is associated with excessive daytime sleepiness, but its causality remains unclear. We aimed to assess the extent to which intentional weight loss affects daytime sleepiness. Electronic databases were searched through 24 October 2016. Studies involving overweight or obese adults, a weight loss intervention and repeated valid measures of daytime sleepiness were included in the review. Two independent reviewers extracted data on study characteristics, main outcome (change in daytime sleepiness score standardized by standard deviation of baseline sleepiness scores), potential mediators (e.g. amount of weight loss and change in apnoea-hypopnoea index) and other co-factors (e.g. baseline demographics). Forty-two studies were included in the review. Fifteen before-and-after studies on surgical weight loss interventions showed large improvements in daytime sleepiness, with a standardized effect size of -0.97 (95% confidence interval [CI] -1.21 to -0.72). Twenty-seven studies on non-surgical weight loss interventions showed small-to-moderate improvement in daytime sleepiness, with a standardized effect size of -0.40 (95%CI -0.52 to -0.27), with no difference between controlled and before-and-after studies. We found a nonlinear association between amount of weight loss and change in daytime sleepiness. This review suggests that weight loss interventions improve daytime sleepiness, with a clear dose-response relationship. This supports the previously hypothesized causal effect of obesity on daytime sleepiness. It is important to assess and manage daytime sleepiness in obese patients.

Polyvinylpyrrolidone-Based Bio-Ink Improves Cell Viability and Homogeneity during Drop-On-Demand Printing

Drop-on-demand (DOD) bioprinting has attracted huge attention for numerous biological applications due to its precise control over material volume and deposition pattern in a contactless printing approach. 3D bioprinting is still an emerging field and more work is required to improve the viability and homogeneity of printed cells during the printing process. Here, a general purpose bio-ink was developed using polyvinylpyrrolidone (PVP) macromolecules. Different PVP-based bio-inks (0%-3% w/v) were prepared and evaluated for their printability; the short-term and long-term viability of the printed cells were first investigated. The Z value of a bio-ink determines its printability; it is the inverse of the Ohnesorge number (Oh), which is the ratio between the Reynolds number and a square root of the Weber number, and is independent of the bio-ink velocity. The viability of printed cells is dependent on the Z values of the bio-inks; the results indicated that the cells can be printed without any significant impairment using a bio-ink with a threshold Z value of ≤9.30 (2% and 2.5% w/v). Next, the cell output was evaluated over a period of 30 min. The results indicated that PVP molecules mitigate the cell adhesion and sedimentation during the printing process; the 2.5% w/v PVP bio-ink demonstrated the most consistent cell output over a period of 30 min. Hence, PVP macromolecules can play a critical role in improving the cell viability and homogeneity during the bioprinting process.

Microvalve-based bioprinting – process, bio-inks and applications

DOD microvalve-based bioprinting system provides a highly advanced manufacturing platform that facilitates precise control over the cellular and biomaterial deposition in a highly reproducible and reliable manner. This article highlights promising directions to transform microvalve-based bioprinting into an enabling technology that will potentially drive significant advances in the field of TERM.

Circulating tumour cells and the epithelial mesenchymal transition in colorectal cancer

Circulating tumour cells (CTCs) hold great potential as liquid biopsies to prognosticate disease and guide treatment in colorectal cancer. However, their emerging role in determining the molecular phenotype of tumour metastasis carries even more promising clinical use in the provision of comprehensive biomarker detection for targeted therapies and determination of drug resistance. The isolation of CTCs is technology dependent, and in the case of epithelial cell adhesion molecule-based platforms, the ability to detect cells that have undergone the epithelial to mesenchymal transition (EMT) is ineffective. CTCs displaying a mesenchymal phenotype are believed to have an increased metastatic potential. The rarity of CTCs provides another challenge in the enumeration of these cells. The future will likely involve the analysis of individual CTCs at any stage of the EMT in order to provide real-time phenotypic and molecular snapshots capable of tracking the dynamic evolution of tumour progression over time.

Accuracy and reliability of the i-STAT point-of-care device for the determination of haemoglobin concentration before and after major blood loss

We investigated the accuracy of i-STAT(®) (Abbott Point of Care Inc., Princeton, NJ, USA) haemoglobin (Hb) measurement in surgical patients with an estimated blood loss of ≥25% of total blood volume. Blood tests for i-STAT(®) Hb, laboratory Hb (Sysmex XE-2100(™), Sysmex Corporation, Kobe, Japan) and total plasma proteins were obtained at the start of surgery (T=0) and when an estimated 25% total blood volume loss had occurred (T=1). Thirty-one patients were recruited. The coefficient of variation of the paired i-STAT(®) Hb estimates was 2.8% and 2.9% at T=0 and T=1, respectively. The mean difference between i-STAT(®) and laboratory Hb was -7.6 g/l (standard deviation 6.5) at T=0 and -5.1 g/l (standard deviation 12) at T=1. The mean total plasma protein difference (total plasma protein T=0 minus T=1) was 13.6 g/l (95% confidence interval 10.2 to 17.0). There was poor correlation between total plasma protein and bias in i-STAT(®) measurements. The i-STAT(®) Hb had an acceptable coefficient of variation, but the Hb levels were lower than those estimated by the laboratory. The standard deviation of i-STAT(®) Hb was greater after ≥25% estimated total blood volume loss. Clinicians should not use the i-STAT(®) Hb in isolation for clinical decision-making when considering blood transfusion in a situation of 25% or greater blood loss.

OCT4 as a target of miR-34a stimulates p63 but inhibits p53 to promote human cell transformation

Human cell transformation is a key step for oncogenic development, which involves multiple pathways; however, the mechanism remains unclear. To test our hypothesis whether cell oncogenic transformation shares some mechanisms with the process of reprogramming non-stem cells to induced pluripotent stem cells (iPSC), we studied the relationship among the key factors for promoting or inhibiting iPSC in radiation-transformed human epithelial cell lines derived from different tissues (lung, breast and colon). We unexpectedly found that p63 and OCT4 were highly expressed (accompanied by low expressed p53 and miR-34a) in all transformed cell lines examined when compared with their non-transformed counterparts. We further elucidated the relationship of these factors: the 3p strand of miR-34a directly targeted OCT4 by binding to the 3′ untranslated region (3′-UTR) of OCT4 and, OCT4, in turn, stimulated p63 but inhibited p53 expression by binding to a specific region of the p63 or p53 promoter. Moreover, we revealed that the effects of OCT4 on promoting cell oncogenic transformation were by affecting p63 and p53. These results support that a positive loop exists in human cells: OCT4 upregulation as a consequence of inhibition of miR-34a, promotes p63 but suppresses p53 expression, which further stimulates OCT4 upregulation by downregulating miR-34a. This functional loop contributes significantly to cell transformation and, most likely, also to the iPSC process.

Circulating tumour cells and circulating free nucleic acid as prognostic and predictive biomarkers in colorectal cancer

The detection of circulating tumour cells or circulating free tumour nucleic acids can potentially guide treatment and inform prognosis in colorectal cancer using minimally invasive "liquid biopsies". Current literature supports the notion that high circulating tumour cell counts or presence of tumour nucleic acid correlate with inferior clinical outcomes for patients, but they are not yet part of routine clinical care. Future research evolves around the examination of the molecular phenotype of circulating tumour cells. The key unanswered areas include differentiating between circulating tumour cell presence and their proliferative capacity and dormancy, identifying tumour heterogeneity and understanding the epithelial-mesenchymal transition.

Morphometric sex determination of Milky and Painted Storks in captivity

Logistic regression was applied to develop a morphometric sexing method of two closely related stork species that were previously sexed through amplification of the CHD gene. Tarsus length (TL) and bill length (BL) measurements were recorded from captive populations of adult Milky Stork (Mycteria cinerea) (n = 60) and Painted Stork (Mycteria leucocephala) (n = 58) at Zoo Negara Malaysia. Despite having monomorphic plumages, both stork species exhibited normal sexual size dimorphism in which males were significantly larger than females in the tested variables. Based on logistic regression analysis, BL correctly classified the sex of sampled individuals from Painted and Milky stork with an overall predicted accuracy of 94.8 and 90.0%, respectively. However, TL measurements generated a lower predicted accuracy level of 86.2% and a same accuracy level of 90% on the sex classification of individuals from Painted and Milky stork, respectively. By comparing the measurements of both species, only the average BL measurements of the Milky storks were significantly lower than that of Painted storks (t-test, P80.001). The logistic regression equation in this study may serve as a simple and more practical option for sexing Milky and Painted storks for their breeding and conservation programmes.

Very long-term outcome of pure lupus membranous nephropathy treated with glucocorticoid and azathioprine

The aim of this study is to report the long-term outcome of pure membranous lupus nephropathy (MLN) treated with glucocorticoid and azathioprine (AZA). A cohort of patients with SLE who had biopsy-confirmed pure MLN was treated initially with prednisone (0.8-1.0 mg/kg/day) and AZA (targeted to 2 mg/kg/day). Patients were followed for the following outcomes: remission rate at 12 months, renal flares, extra-renal flares and renal function deterioration. The cumulative risks of renal flares and renal function decline were studied by Kaplan-Meier analysis. Thirty-eight patients were studied (31 women; age 35.0 +/- 9.2 years; mean SLE duration 48.5 +/- 59 months; WHO Class Va 45%, Vb 55%). Twenty-two (58%) patients were nephrotic and four (11%) were hypertensive at presentation. All patients were treated with prednisolone (0.85 +/- 0.24 mg/kg/day) and AZA (1.72 +/- 0.43 mg/kg/day). At 12 months, 24 (67%) patients achieved complete response (CR), 8 (22%) had partial response (PR) and 4 (11%) were treatment resistant. After a follow-up of 12 +/- 5.8 years, 19 episodes of renal flares (15 proteinuric and 4 nephritic) occurred in 13 (34%) patients. The cumulative risks of renal flares at 5, 10 and 15 years were 19.4, 32.0 and 36.8%, respectively. Retreatment with an augmented dosage of prednisolone, +/- another immunosuppressive agent, resulted in CR and PR in 15 (79%) and 4 (21%) of these flare episodes, respectively. At last visit, three (8%) patients had doubling of serum creatinine, whereas six (16%) patients had decline of creatinine clearance by >/=30% (none developed end stage renal failure). Seven episodes of thromboembolic complications occurred in five (13%) patients and 11 episodes of infective complications (five major, six minor) were reported in seven (18%) patients. In the absence of co-existing proliferative lesions, MLN runs a relatively benign course with low risk of renal function deterioration. Treatment with high-dose prednisolone and AZA is effective, inexpensive and well-tolerated. Prolonged observation shows that one of three patients develop renal flares, which are often proteinuric and responsive to reinduction therapy.

Nodular regenerative hyperplasia of the liver associated with systemic lupus erythematosus: three cases

Nodular regenerative hyperplasia of the liver, characterised by regenerative nodules distributed throughout the liver in the absence of fibrosis, is a rare but important complication of systemic lupus erythematosus. The main consequence of nodular regenerative hyperplasia of the liver is non-cirrhotic portal hypertension. This condition is probably underdiagnosed, as many of these patients may remain asymptomatic. Furthermore, nodular regenerative hyperplasia of the liver may be misdiagnosed as cirrhosis. We describe three female patients with nodular regenerative hyperplasia of the liver associated with systemic lupus erythematosus. All three patients have clinical manifestations of portal hypertension, and all were initially misdiagnosed as having cryptogenic cirrhosis.

Spontaneous intra-hepatic haemorrhage in a patient with fever of unknown origin

Polyarteritis nodosa is a systemic necrotising vasculitis that affects the small- and medium-sized arteries. Multifocal aneurysmal formation in the renal, hepatic, and mesenteric vasculature is a hallmark of this condition, and spontaneous aneurysmal rupture may occur, resulting in life-threatening haemorrhage. We describe a 42-year-old man who initially presented with fever of unknown origin. A diagnosis could not be reached at that time despite extensive investigations. The fever subsided spontaneously after 8 weeks, and the patient remained well for 6 years until he was admitted again for evaluation of fever. During his hospital stay, he developed a spontaneous massive intra-hepatic haemorrhage resulting in hepatic rupture and a haemoperitoneum. The bleeding was controlled at emergency laparotomy. An abdominal angiography demonstrated multiple microaneurysms in the hepatic and mesenteric arterial vasculature. The clinical findings suggested polyarteritis nodosa, and the source of bleeding was probably a ruptured intra-hepatic artery aneurysm.

Seroprevalence of hepatitis C in intravenous opioid users presenting in the early phase of injecting drug use in Singapore

INTRODUCTION

All over the world, Hepatitis C virus (HCV) accounts for an estimated 130 million chronic infections. Injection drug use has become one of the most important risk factors for HCV, and within the injection drug user population, the prevalence of HCV antibody ranges from 70 to 95 percent depending on an individual's length of use and the prevalence of infection in the community. This study was undertaken to determine the prevalence of and the risk factors for Hepatitis C antibodies in injecting drug users presenting to the Community Addictions Management Programme (CAMP) in Singapore.

METHODS

Eligibility criteria for inclusion in this study were all intravenous buprenorphine users presenting to CAMP. 106 subjects, who consented to the study, completed an interviewer-administered questionnaire, and underwent a urine and blood analysis.

RESULTS

The prevalence rate for HCV was 42.5 percent among the subjects included in our study. The odds of seroprevalence in those sharing needles were 5.6 times that of those who were not, and the odds of seroprevalence among those using with others (peers or partners) were 6.3 times, as compared to among those who were individual users. Racial differences were also seen, but these could be accounted for by the sharing of needles.

CONCLUSION

This study provides important local data at the onset of an early buprenorphine-injecting epidemic in Singapore. This data is useful for disease prevention and healthcare planning.

Non-typhoid Salmonella mycotic aneurysm of the aortic arch

Salmonella mycotic aneurysm is a rare but potentially fatal condition. Mortality is high without timely intervention. The clinical presentation is protean and early diagnosis requires a high degree of clinical alertness. Prompt surgical intervention and prolonged antimicrobial therapy are keys to successful treatment. We report an 81-year-old man with an atypical presentation of Salmonella mycotic aneurysm in the aortic arch. The case highlights the need to evaluate all patients over 50 years with non-typhoid Salmonella bacteraemia for possible endovascular infections. Contrast-enhanced computed tomography is useful for making an early diagnosis of this disease.

Unique hepatic imaging features in a patient with nodular regenerative hyperplasia of the liver associating with systemic lupus erythematosus

Nodular regenerative hyperplasia (NRH) of the liver, characterized by regenerative nodules distributed throughout the liver in the absence of fibrosis, is a rare but important complication of systemic lupus erythematosus (SLE). The main consequence of NRH is non-cirrhotic portal hypertension. We describe a female patient who had immune thrombocytopenia in association with elevated liver enzymes and evidence of portal hypertension as initial manifestations of SLE. Computed tomographic scan and magnetic resonance imaging of the liver in this patient showed enhancing periportal tubular structures distributed throughout the liver. The diagnosis of NRH was eventually disclosed by transcutaneous needle liver biopsy. The pattern of radiological abnormality in this patient has not been described previously in NRH. In addition, we believe this is a first reported case of SLE presenting with immune thrombocytopenia in association with NRH.

Lymphopenia at presentation is associated with increased risk of infections in patients with systemic lupus erythematosus

BACKGROUND

Patients with systemic lupus erythematosus (SLE) frequently suffer from infections, but the predisposing risk factors, as well as the exact frequency and nature of such infections, are not fully understood.

AIM

To describe the frequency, types and risk factors for infections in a group of Chinese patients in the early stage of SLE in Hong Kong.

DESIGN

Retrospective record study.

METHODS

We reviewed the case records of 91 Chinese SLE patients, presenting <12 months after SLE diagnosis. Details of major infections (requiring intravenous antimicrobial therapy, or any confirmed mycobacterial infection) and minor infections were reviewed. Clinical and laboratory features, the systemic lupus erythematosus disease activity index (SLEDAI) at presentation and drug treatment were recorded and analysed.

RESULTS

There were 48 major infections and 62 minor infections during 260 patient-years of follow-up. A lymphocyte count < or =1.0 x 10(9)/l at presentation was independently associated with an increased risk for major infection: hazard ratio 4.7 (95%CI 1.6-13.7), p = 0.005. SLEDAI, use of corticosteroids and immunosuppressive therapy were all not associated with increased risk of infection.

DISCUSSION

Lymphopenia was an important risk factor for major infections in this group of Chinese patients in the early stages of SLE. SLE patients with lymphopenia at presentation should be closely monitored for the development of infective complications.

The impact of diabetes mellitus on the prognostic value of a normal dobutamine stress echocardiogram in patients with intermediate to high cardiovascular risk

INTRODUCTION

There is currently limited data on the prognostic value of a normal dobutamine stress echocardiogram (DSE) in patients with intermediate to high cardiovascular risk. The impact of diabetes mellitus, recently recognised as a cardiovascular risk-equivalent, has not been previously evaluated. This study aims to determine the prognostic value of a normal DSE in these patients.

METHODS

The study population includes all patients with two cardiovascular risk factors or diabetes mellitus and a normal DSE (baseline and peak stress) with three months follow-up. A total of 122 patients (47 females, 75 males; mean age 59.6 years) were recruited. Impact of diabetes mellitus on subsequent cardiovascular events was determined.

RESULTS

Diabetes mellitus was present in 32.8 percent, hypertension in 72.1 percent, smoking in 27.0 percent, family history of premature coronary artery disease in 15.6 percent, and hypercholesterolemia in 66.4 percent. On follow-up until 6.4 years (mean 4.1 years), there were four myocardial infarctions (0.8 percent per patient/year) and five revascularisation procedures (1.0 percent per patient/year). The majority of adverse events occurred among patients with diabetes mellitus (three out of four myocardial infarctions; four out of five revascularisations). Diabetes mellitus independently predicted subsequent cardiac events on both univariate and multivariate analyses (p value is equal to 0.015 and 0.011, respectively). Presence of diabetes mellitus also conferred a worse outcome on survival analysis (p value is equivalent to 0.0046).

CONCLUSION

The presence of diabetes mellitus adversely affects clinical outcome despite a normal DSE. Patients without diabetes mellitus, but with intermediate to high cardiovascular risk, and a normal DSE have a better medium term outcome.

Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study

BACKGROUND

We investigated the temporal progression of the clinical, radiological, and virological changes in a community outbreak of severe acute respiratory syndrome (SARS).

METHODS

We followed up 75 patients for 3 weeks managed with a standard treatment protocol of ribavirin and corticosteroids, and assessed the pattern of clinical disease, viral load, risk factors for poor clinical outcome, and the usefulness of virological diagnostic methods.

FINDINGS

Fever and pneumonia initially improved but 64 (85%) patients developed recurrent fever after a mean of 8.9 (SD 3.1) days, 55 (73%) had watery diarrhoea after 7.5 (2.3) days, 60 (80%) had radiological worsening after 7.4 (2.2) days, and respiratory symptoms worsened in 34 (45%) after 8.6 (3.0) days. In 34 (45%) patients, improvement of initial pulmonary lesions was associated with appearance of new radiological lesions at other sites. Nine (12%) patients developed spontaneous pneumomediastinum and 15 (20%) developed acute respiratory distress syndrome (ARDS) in week 3. Quantitative reverse-transcriptase (RT) PCR of nasopharyngeal aspirates in 14 patients (four with ARDS) showed peak viral load at day 10, and at day 15 a load lower than at admission. Age and chronic hepatitis B virus infection treated with lamivudine were independent significant risk factors for progression to ARDS (p=0.001). SARS-associated coronavirus in faeces was seen on RT-PCR in 65 (97%) of 67 patients at day 14. The mean time to seroconversion was 20 days.

INTERPRETATION

The consistent clinical progression, shifting radiological infiltrates, and an inverted V viral-load profile suggest that worsening in week 2 is unrelated to uncontrolled viral replication but may be related to immunopathological damage.

Inflammatory pseudotumor of the heart causing aortic regurgitation

Inflammatory pseudotumor is a tumor-like reactive lesion of unknown etiology that rarely affects the heart. We describe an unusual case of a cardiac inflammatory pseudotumor that involved the aortic valve and caused regurgitation in a 62-year-old man. The lesion was excised and the aortic valve was replaced, resulting in a favorable outcome for the patient.

An efficient room-temperature silicon-based light-emitting diode

There is an urgent requirement for an optical emitter that is compatible with standard, silicon-based ultra-large-scale integration (ULSI) technology. Bulk silicon has an indirect energy bandgap and is therefore highly inefficient as a light source, necessitating the use of other materials for the optical emitters. However, the introduction of these materials is usually incompatible with the strict processing requirements of existing ULSI technologies. Moreover, as the length scale of the devices decreases, electrons will spend increasingly more of their time in the connections between components; this interconnectivity problem could restrict further increases in computer chip processing power and speed in as little as five years. Many efforts have therefore been directed, with varying degrees of success, to engineering silicon-based materials that are efficient light emitters. Here, we describe the fabrication, using standard silicon processing techniques, of a silicon light-emitting diode (LED) that operates efficiently at room temperature. Boron is implanted into silicon both as a dopant to form a p-n junction, as well as a means of introducing dislocation loops. The dislocation loops introduce a local strain field, which modifies the band structure and provides spatial confinement of the charge carriers. It is this spatial confinement which allows room-temperature electroluminescence at the band-edge. This device strategy is highly compatible with ULSI technology, as boron ion implantation is already used as a standard method for the fabrication of silicon devices.

Safety of disease modifying anti-rheumatic agents in rheumatoid arthritis patients with chronic viral hepatitis

OBJECTIVE

To examine the safety of the use of disease modifying anti-rheumatic drugs (DMARDs) in rheumatoid arthritis (RA) patients with chronic viral hepatitis (CVH).

METHODS

Records of 600 Chinese patients satisfying the ARA criteria for RA in two rheumatology centers were reviewed. Patients with CVH were studied. Liver enzymes were checked before (baseline) and during DMARD use at 3-month intervals or more frequently if necessary. Drug-episodes (D-Ep), defined as the continuous use of DMARD, singly or in combination, for more than 6 months in a patient, were analysed. Changes in serum liver alanine transaminase (ALT) levels as multiples of the upper range of normal were taken to reflect the severity of hepatotoxicity. Changes of ALT to > or = 1.5 times the upper range of normal if they were measured at baseline or > or = 2 times the upper range of normal if they were measured during and after the use of DMARD were considered as abnormal. Control patients included those with CVH alone (n = 623) or RA without CVH (n = 62) matched for age, sex and D-Ep.

RESULTS

30 RA patients were found to have concomitant CVH. One patient was excluded because of use of NSAID alone (n = 1). Among the 29 patients, 23 were HBsAg +ve and 6 were anti-HCV Ab +ve. A total of 47 D-Ep were analysed. 20/47 (42.6%) of D-Ep in 16/29 (55.2%) RA + CVH patients developed abnormal ALT levels after a mean 1.9-year duration of DMARD use. This was statistically significant when compared with 13/94 (13.8%) of D-Ep which ended with abnormal ALT levels in 13/62 (21%) patients with RA alone (p < 0.0001 for D-Ep which ended up with abnormal ALT, and p < 0.02 for the number of patients who developed abnormal ALT) and 128/623 (20.5%) patients with CVH alone (p < 0.005). 53% (9/17) of hydroxychloroquine (HCQ) D-Ep were associated with an abnormal outcome. Corresponding figures for sulphasalazine (SAZP) and oral or intramuscular gold preparations were 55.6% (5/9) and 0% (0/3) respectively. Two patients on methotrexate, used either singly or in combination, had normal ALT levels throughout the study period. One patient on azathioprine developed reactivation of hepatitis B infection. When D-Ep of the RA + CVH group were further analysed, 16/43 (37.2%) and 4/4 (100%) D-Ep which started with normal and abnormal baseline ALT respectively developed further liver enzyme derangement.

CONCLUSION

The use of DMARD in RA + CVH patients is associated with a high incidence of hepatotoxicity. The effect is likely to be synergistic. This includes drugs such as HCQ, which is generally believed to be less hepatotoxic.

Cloning and characterization of two hydrophobin genes differentially expressed during fruit body development in Lentinula edodes

Hydrophobins play important roles in morphogenesis and pathogenesis in fungi and fruit development in mushrooms. Two genes encoding hydrophobins (Le.hyd1 and Le.hyd2) were isolated during sequencing of random clones from a primordial cDNA library of Lentinula edodes. The nucleotide sequences of these two genes were determined. These two genes are 760 and 738 bp in length and the deduced amino acid sequences are homologous to various fungal hydrophobins with characteristic cysteine spacing. These hydrophobin genes are Class I hydrophobins judging by their conserved domains and hydropathy patterns. The transcript level of Le.hyd1 is high in primordium and that of Le.hyd2 is high in dikaryotic mycelial tissues. Poor expression of these two genes in monokaryotic parents indicates that these two genes are under mating-type regulation. We thus suggest that differential expression of these two L. edodes hydrophobins during fruit development may contribute to their distinct roles in fruiting of this mushroom.

Initial experience of radiofrequency catheter ablation of supraventricular tachycardia in paediatric patients

INTRODUCTION

The management of supraventricular tachycardia (SVT) in paediatric patients until recently has frequently been pharmacologic therapy, but this approach suffers from the drawbacks of treatment failure, development of drug intolerance and/or side-effects.

AIM

In keeping with recent advances in paediatric cardiology, we share our experience with radiofrequency catheter ablation as an alternative and definitive modality of therapy.

MATERIALS AND METHOD

4 young patients with recurrent SVT underwent electrophysiologic study followed by radiofrequency ablation of the accessory pathways.

RESULTS

Resolution of symptoms was achieved in all patients and no major complication was encountered.

CONCLUSIONS

The ability to ablate permanently the reentrant circuit responsible for SVT has now permitted cure by non-surgical means, and is an important alternative to drug therapy in the management of SVT in children.

Diagnosis of pacemaker lead infection using transoesophageal echocardiography: a case report

INTRODUCTION

Vegetative lead infection is an uncommon complication of permanent pacemaker implantation. The diagnosis is difficult using conventional imaging methods.

CLINICAL PICTURE

An elderly Indian woman with a history of diabetes mellitus developed Staphylococcus aureus infection after implementation of a permanent pacemaker. Following a non-diagnostic transthoracic echocardiogram, transoesophageal echocardiography was performed and showed a large vegetative mass attached to the pacemaker lead within the right atrium.

TREATMENT

The pacemaker was removed and intravenous vancomycin administered for six weeks.

OUTCOME

She was discharged well but demised two months later from a second episode of septicaemia.

CONCLUSIONS

Pacemaker lead infection remains a challenging management problem. Transoesophageal echocardiography can facilitate its diagnosis.

Negative selection: a method for obtaining low-abundance cDNAs using high-density cDNA clone arrays

The identification of the entire complement of genes expressed in a cell, tissue, or organism provides a framework for understanding biological properties and establishes a tool set for subsequent functional studies. The large-scale sequencing of randomly selected clones from cDNA libraries has been successfully employed as a method for identifying a large fraction of these expressed genes. However, this approach is limited by the inherent redundancy of cellular transcripts reflecting widely variant levels of gene transcription. As a result, a high percentage of transcript duplications are encountered as the number of sequenced clones accrues. To address this problem, we have developed a negative hybridization selection method that employs the hybridization of complex cDNA probes to high-density arrays of cDNA clones and the subsequent selection of clones with a null or low hybridization signal. This approach was applied to a cDNA library constructed from normal human prostate tissue and resulted in the reduction of highly expressed prostate cDNAs from 6.8 to 0.57% with an overall decline in clone redundancy from 33 to 11%. The selected clones also reflected a more diverse cDNA population, with 89% of the clones representing distinctly different cDNAs compared with 67% of the randomly selected clones. This method compares favorably with cDNA library re-association normalization approaches and offers several distinct advantages, including the flexibility to use previously prepared libraries, and the ability to employ an iterative screening approach for continued accrual of cDNAs representing rare transcripts.

Prostate cancer expression profiling by cDNA sequencing analysis

Prostate cancer is a frequently diagnosed solid tumor that is originated mostly from prostate epithelium. One of the key issues in prostate cancer research is to develop molecular markers that can effectively detect and distinguish the progression and malignancy of prostate tumors. Automated, single-pass cDNA sequencing was utilized to rapidly identify expressed genes in a number of cDNA libraries constructed from various normal and tumor prostatic tissues. These included cell lines as well as short-term epithelial culture. A total of 6604 expressed sequence tags (ESTs) were generated and searched against on-line nucleotide and protein databases. A relational database centric software system was constructed to process, store, and analyze EST data rapidly. cDNA contigs were also obtained by assembly of multiple EST sequences. Protein structural signatures were annotated using motif analysis tools including BLOCKS and an in-house-designed neural network. Cross-library comparisons revealed their unique gene expression profiles. Several differentially expressed cDNA clones were identified, and their expression patterns were confirmed by RNA dot blot and RT-PCR analyses.

Spontaneous aortic laceration causing flail aortic valve and acute aortic regurgitation

Spontaneous laceration of the aorta is an unusual cause of flail aortic valve. We report a case of acute aortic regurgitation caused by flail aortic valve as a result of spontaneous laceration of the ascending aorta. The role of transesophageal echocardiography in the diagnosis of this condition is discussed.