A review of smell and taste dysfunction in COVID-19 patients

@#and taste loss were early subclinical symptoms of COVID-19patients. The objective of this review was to identify theincidence of smell and taste dysfunction in COVID-19,determine the onset of their symptoms and the risk factorsof anosmia, hyposmia, ageusia or dysgeusia for COVID-19infection.Methods: We searched the PubMed and Google Scholar on15th May 2020, with search terms including SARS-COV-2,coronavirus, COVID-19, hyposmia, anosmia, ageusia anddysgeusia. The articles included were cross sectionalstudies, observational studies and retrospective orprospective audits, letters to editor and shortcommunications that included a study of a cohort ofpatients. Case reports, case-series and interventionalstudies were excluded. Discussion: A total of 16 studies were selected. Incidence ofsmell and taste dysfunction was higher in Europe (34 to86%), North America (19 to 71%) and the Middle East (36 to98%) when compared to the Asian cohorts (11 to 15%) inCOVID-19 positive patients. Incidence of smell and tastedysfunction in COVID-19 negative patients was low incomparison (12 to 27%). Total incidence of smell and tastedysfunction from COVID-19 positive and negative patientsfrom seven studies was 20% and 10% respectively.Symptoms may appear just before, concomitantly, orimmediately after the onset of the usual symptoms. Occurspredominantly in females. When occurring immediately afterthe onset of the usual symptoms, the median time of onsetwas 3.3 to 4.4 days. Symptoms persist for a period of sevento 14 days. Patients with smell and taste dysfunction werereported to have a six to ten-fold odds of having COVID-19.Conclusion: Smell and taste dysfunction has a highincidence in Europe, North America, and the Middle East.The incidence was lower in the Asia region. It is a strong riskfactor for COVID-19. It may be the only symptom and shouldbe added to the list of symptoms when screening for COVID-19.KEYW

Electrospun Collagen Nanofibers and Their Applications in Skin Tissue Engineering

Electrospinning is a simple and versatile technique to fabricate continuous fibers with diameter ranging from micrometers to a few nanometers. To date, the number of polymers that have been electrospun has exceeded 200. In recent years, electrospinning has become one of the most popular scaffold fabrication techniques to prepare nanofiber mesh for tissue engineering applications. Collagen, the most abundant extracellular matrix protein in the human body, has been electrospun to fabricate biomimetic scaffolds that imitate the architecture of native human tissues. As collagen nanofibers are mechanically weak in nature, it is commonly cross-linked or blended with synthetic polymers to improve the mechanical strength without compromising the biological activity. Electrospun collagen nanofiber mesh has high surface area to volume ratio, tunable diameter and porosity, and excellent biological activity to regulate cell function and tissue formation. Due to these advantages, collagen nanofibers have been tested for the regeneration of a myriad of tissues and organs. In this review, we gave an overview of electrospinning, encompassing the history, the instrument settings, the spinning process and the parameters that affect fiber formation, with emphasis given to collagen nanofibers' fabrication and application, especially the use of collagen nanofibers in skin tissue engineering.

Attachment, Proliferation, and Morphological Properties of Human Dermal Fibroblasts

Introduction: Collagen type I is widely used as a biomaterial for tissue-engineered substitutes. This study aimed to fabricate different three-dimensional (3D) scaffolds using ovine tendon collagen type I (OTC-I), and compare the attachment, proliferation and morphological features of human dermal fibroblasts (HDF) on the scaffolds. Methods: This study was conducted between the years 2014 to 2016 at the Tissue Engineering Centre, UKM Medical Centre. OTC-I was extracted from ovine tendon, and fabricated into 3D scaffolds in the form of sponge, hydrogel and film. A polystyrene surface coated with OTC-I was used as the 2D culture condition. Genipin was used to crosslink the OTC-I. A noncoated polystyrene surface was used as a control. The mechanical strength of OTC-I scaffolds was evaluated. Attachment, proliferation and morphological features of HDF were assessed and compared between conditions. Results: The mechanical strength of OTC-I sponge was significantly higher than that of the other scaffolds. OTC-I scaffolds and the coated surface significantly enhanced HDF attachment and proliferation compared to the control, but no differences were observed between the scaffolds and coated surface. In contrast, the morphological features of HDF including spreading, filopodia, lamellipodia and actin cytoskeletal formation differed between conditions. Conclusion: OTC-I can be moulded into various scaffolds that are biocompatible and thus could be suitable as scaffolds for developing tissue substitutes for clinical applications and in vitro tissue models. However, further study is required to determine the effect of morphological properties on the functional and molecular properties of HDF.

Recent Updates in Neuroprotective and Neuroregenerative Potential of Centella asiatica

Centella asiatica, locally well known in Malaysia as pegaga, is a traditional herb that has been used widely in Ayurvedic medicine, traditional Chinese medicine, and in the traditional medicine of other Southeast Asian countries including Malaysia. Although consumption of the plant is indicated for various illnesses, its potential neuroprotective properties have been well studied and documented. In addition to past studies, recent studies also discovered and/or reconfirmed that C. asiatica acts as an antioxidant, reducing the effect of oxidative stress in vitro and in vivo. At the in vitro level, C. asiatica promotes dendrite arborisation and elongation, and also protects the neurons from apoptosis. In vivo studies have shown that the whole extract and also individual compounds of C. asiatica have a protective effect against various neurological diseases. Most of the in vivo studies on neuroprotective effects have focused on Alzheimer’s disease, Parkinson’s disease, learning and memory enhancement, neurotoxicity and other mental illnesses such as depression and anxiety, and epilepsy. Recent studies have embarked on finding the molecular mechanism of neuroprotection by C. asiatica extract. However, the capability of C. asiatica in enhancing neuroregeneration has not been studied much and is limited to the regeneration of crushed sciatic nerves and protection from neuronal injury in hypoxia conditions. More studies are still needed to identify the compounds and the mechanism of action of C. asiatica that are particularly involved in neuroprotection and neuroregeneration. Furthermore, the extraction method, biochemical profile and dosage information of the C. asiatica extract need to be standardised to enhance the economic value of this traditional herb and to accelerate the entry of C. asiatica extracts into modern medicine.

Human Adipose Tissue Derived Stem Cells as a Source of Smooth Muscle Cells in the Regeneration of Muscular Layer of Urinary Bladder Wall

Background: Adipose tissue provides an abundant source of multipotent cells, which represent a source of cell-based regeneration strategies for urinary bladder smooth muscle repair. Our objective was to confirm that adipose-derived stem cells (ADSCs) can be differentiated into smooth muscle cells. Methods: In this study, adipose tissue samples were digested with 0.075% collagenase, and the resulting ADSCs were cultured and expanded in vitro. ADSCs at passage two were differentiated by incubation in smooth muscle inductive media (SMIM) consisting of MCDB I31 medium, 1% FBS, and 100 U/mL heparin for three and six weeks. ADSCs in non-inductive media were used as controls. Characterisation was performed by cell morphology and gene and protein expression. Result: The differentiated cells became elongated and spindle shaped, and towards the end of six weeks, sporadic cell aggregation appeared that is typical of smooth muscle cell culture. Smooth muscle markers (i.e. alpha smooth muscle actin (ASMA), calponin, and myosin heavy chain (MHC)) were used to study gene expression. Expression of these genes was detected by PCR after three and six weeks of differentiation. At the protein expression level, ASMA, MHC, and smoothelin were expressed after six weeks of differentiation. However, only ASMA and smoothelin were expressed after three weeks of differentiation. Conclusion: Adipose tissue provides a possible source of smooth muscle precursor cells that possess the potential capability of smooth muscle differentiation. This represents a promising alternative for urinary bladder smooth muscle repair.