Modelling the combined effect of surface roughness and topography on bacterial attachment

Bacterial attachment is a complex process affected by flow conditions,imparted stresses,and the sur-face properties and structure of both the supporting material and the cell.Experiments on the initial attachment of cells of the bacterium Streptococcus gordonii (S.gordonii),an important early coloniser of dental plaque,to samples of stainless steel (SS) have been reported in this work.The primary aim motivating this study was to establish what affect,if any,the surface roughness and topology of sam-ples of SS would have on the initial attachment of cells of the bacterium S.gordonii.This material and bacterium were chosen by virtue of their relevance to dental implants and dental implant infections.Prior to bacterial attachment,surfaces become conditioned by the interfacing environment (salivary pellicle from the oral cavity for instance).For this reason,cell attachment to samples of SS pre-coated with saliva was also studied.By implementing the Extended Derjaguin Landau Verwey and Overbeek(XDLVO) theory coupled with convection-diffusion-reaction equations and the surface roughness infor-mation,a computational model was developed to help better understand the physics of cell adhesion.Surface roughness was modelled by reconstructing the surface topography using statistical parame-ters derived from atomic force microscopy (AFM) measurements.Using this computational model,the effects of roughness and surface patterns on bacterial attachment were examined quantitatively in both static and flowing fluid environments.The results have shown that rougher surfaces (within the sub-microscale) generally increase bacterial attachment in static fluid conditions which quantitatively agrees with experimental measurements.Under flow conditions,computational fluid dynamics (CFD) simula-tions predicted reduced convection-diffusion inside the channel which would act to decrease bacterial attachment.When combined with surface roughness effects,the computational model also predicted that the surface topographies discussed within this work produced a slight decrease in overall bacterial attachment.This would suggest that the attachment-preventing effects of surface patterns dominate over the adhesion-favourable sub-microscale surface roughness;hence,producing a net reduction in adhered cells.This qualitatively agreed with experimental observations reported here and quantitatively matched experimental observations for low flow rates within measurement error.     

Deformation and osmotic swelling of an elastic membrane capsule in Stokes flows by the immersed interface method

Although permeable and deformable capsules are found in many applications in biological and industrial systems, studies on computational modeling of these capsules are still rather lacking. In this work, the osmotic swelling of a deforming capsule immersed in a diluted binary solution of a non-electrolyte solute under Stokes flows is simulated using the immersed interface method (IIM). The approximate jump conditions for solute concentration are calculated with the use of the Kedem–Katchalsky relations. The capsule membrane is considered to be either semi-permeable or fully permeable, and the material of capsule membrane is assumed to be Neo-Hookean. The employed properties of fluid and membrane lie in the range of a typical biological system. The numerical validation tests indicate that the present calculation procedure has achieved good accuracy in modeling the swelling and deformation of permeable capsules. The capsule swelling (with mass transfer across the membrane) and deformation are tested for different solute concentration fields and membrane permeability properties. Our numerical investigations show that the initial solute concentration field and the membrane permeability properties have much influence on the swelling/deformation of a permeable capsule under Stokes flows.     

Cowpea: an overview on its nutritional facts and health benefits

Cowpea (Vigna unguiculata) is a legume consumed as a high‐quality plant protein source in many parts of the world. High protein and carbohydrate contents with a relatively low fat content and a complementary amino acid pattern to that of cereal grains make cowpea an important nutritional food in the human diet. Cowpea has gained more attention recently from consumers and researchers worldwide as a result of its exerted health beneficial properties, including anti‐diabetic, anti‐cancer, anti‐hyperlipidemic, anti‐inflammatory and anti‐hypertensive properties. Among the mechanisms that have been proposed in the prevention of chronic diseases, the most proven are attributed to the presence of compounds such as soluble and insoluble dietary fiber, phytochemicals, and proteins and peptides in cowpea. However, studies on the anti‐cancer and anti‐inflammatory properties of cowpea have produced conflicting results. Some studies support a protective effect of cowpea on the progression of cancer and inflammation, whereas others did not reveal any. Because there are only a few studies addressing health‐related effects of cowpea consumption, further studies in this area are suggested. In addition, despite the reported favorable effects of cowpea on diabetes, hyperlipidemia and hypertension, a long‐term epidemiological study investigating the association between cowpea consumption and diabetes, cardiovascular disease and cancer is also recommended. © 2018 Society of Chemical Industry     

Health‐beneficial properties of potato and compounds of interest

Potatoes have shown promising health‐promoting properties in human cell culture, experimental animal and human clinical studies, including antioxidant, hypocholesterolemic, anti‐inflammatory, antiobesity, anticancer and antidiabetic effects. Compounds present such as phenolics, fiber, starch and proteins as well as compounds considered antinutritional such as glycoalkaloids, lectins and proteinase inhibitors are believed to contribute to the health benefits of potatoes. However, epidemiological studies exploring the role of potatoes in human health have been inconclusive. Some studies support a protective effect of potato consumption in weight management and diabetes, while other studies demonstrate no effect and a few suggest a negative effect. As there are many biological activities attributed to the compounds present in potato, some of which could be beneficial or detrimental depending on specific circumstances, a long‐term study investigating the association between potato consumption and diabetes, obesity, cardiovascular disease and cancer while controlling for fat intake is needed. © 2016 Society of Chemical Industry     

Muco-ciliary transport: Effect of mucus viscosity, cilia beat frequency and cilia density

In this paper, a two-layer Newtonian fluid model consisting of an upper mucus layer and a lower periciliary layer (PCL) is developed to simulate the muco-ciliary transport process. The objective is to investigate the important factors that may affect the muco-ciliary transport and to understand better the underlying mechanics of some respiratory diseases such as cystic fibrosis. The numerical technique implemented in this study is the projection method combined with the Immersed Boundary Method (IBM) for prescribed ciliary beating patterns. A systematic study of the muco-ciliary transport measured in terms of the mean mucus velocity is performed by changing (i) the viscosity of the mucus, (ii) the cilia beat frequency, (iii) the numbers of cilia, (iv) the thickness of PCL, and (v) the surface tension at the interface between the mucus and PCL. We conclude that the cilia beat frequency, the number of cilia, and the depth of PCL are the critical factors affecting the muco-ciliary transport. Moreover, the present results show that the velocity of mucus layer will be reduced when the length of cilia is larger than the depth of PCL.     

Effect of membrane permeability on capsule substrate adhesion: Computation using immersed interface method

A two-dimensional thin-walled capsule of a flexible permeable membrane is adhered onto a rigid planar substrate under adhesive forces (derived from a potential function). The capsule and the surrounding environment are filled with a diluted binary solution of different solute concentrations. The Stokes flow problem is solved by the immersed interface method (IIM) with equal viscosities for enclosed and surrounding fluid of the capsule. The numerical results obtained are verified against two simplified theoretical solutions with reasonable concurrence. The osmotic inflation of the adhered capsule is studied systematically as a function of solute concentration field and the membrane permeability properties. Our findings indicate that contact length shrinks in dimension and deformation decreases as capsule inflates. Also the equilibrium contact length does not depend on the hydraulic conductivity of the membrane as theoretically expected. Further numerical investigations show that the inflation and detachment of the initially adhered capsule depend significantly on the solute diffusive permeability and the reflection coefficient of capsule membrane.     

Prediction of short-term changes in symptom severity by baseline plasma homovanillic acid levels in schizophrenic patients receiving clozapine

The relationship between pretreatment levels of plasma homovanillic acid (pHVA) and the outcome of clozapine treatment was studied in 18 male patients with schizophrenia who were resistant to treatment with conventional neuroleptics. After 6 months of clozapine treatment, 7 patients demonstrated > or = 20% decrease in the Brief Psychiatric Rating Scale (BPRS) (responders), while 11 patients did not (non-responders). Responders and non-responders did not differ with respect to the baseline pHVA level. The BPRS Positive Symptom scores at 6 weeks and 3 months, but not those at baseline and 6 months, following initiation of clozapine treatment negatively correlated with pHVA levels for all patients. The correlations became stronger when only responders were included. No significant correlation between Positive Symptom scores and pHVA levels was observed for non-responders. The BPRS Total and Negative Symptom scores did not correlate with pHVA for all patients, responders or non-responders at any time. The percent decrease in the BPRS Positive Symptom scores from baseline at 6 weeks following clozapine treatment correlated significantly with pHVA levels in responders. These results suggest that pretreatment levels of pHVA can be used to predict relatively short-term changes in the positive symptoms of patients with schizophrenia receiving clozapine treatment, particularly for clozapine responders.     

Hypolipidemic and hypoglycemic potential of raw,boiled, and sprouted mung beans (Vigna radiata L. Wilczek) in rats

This study was carried out to investigate the hypolipidemic and hypoglycemic potential of raw, boiled, and sprouted mung beans in rats. Oven dried mung bean powders; raw, sprouted, and boiled were included at 30% level in the diet of seven weeks old male Wistar rats maintained for 5 weeks on high (0.5%) cholesterol diet in comparison with control diet. Low serum glucose and triglyceride concentrations (p < .05) in raw and processed mung bean diets fed rats were supported by low serum insulin level in both raw mung bean diet and boiled mung bean diet fed rats. Hypoglycemic effect in sprouted mung bean fed rats was supported by higher α‐amylase inhibitory activity and α‐glucosidase inhibitory activity of sprouted mung beans. Increase in serum non‐HDL cholesterol concentration and decrease in HDL cholesterol concentration caused by high cholesterol diet were modulated (p < .05) by both boiled and sprouted mung bean diets.

Practical applications

Mung bean is a green legume rich in protein, fiber, antioxidants, and phytonutrients. Hypocholesterolemic and hypoglycemic potential of raw mung beans have been shown previously. It is well known that cooking and processing modulate nutritional and biochemical parameters of foods. However, very limited information is available on the effect of processing on functional properties of legumes. Results of this study showed that boiling and sprouting improved the soluble fiber content and hypocholesterolemic potential of mung beans. Thus, the processed mung beans may be more suitable for developing food supplements for patients with hypercholesterolemia.     

Critical review on conventional spectroscopic α-amylase activity detection methods: merits,demerits, and future prospects

α-Amylase is an endoenzyme that catalyses the hydrolysis of internal α-l,4 glycosidic linkages in polysaccharides to produce maltose, maltotriose, and α-limit dextrins. It is widely used in the laboratorial and industrial workflow for several applications. There are several methods utilizing different techniques and substrates to assess α-amylase activity, among which the spectroscopic methods have found widespread applicability due to their ease of use and cost-effectiveness. Depending upon the reaction principle, these assays are classified into four groups: reducing sugar, enzymatic, chromogenic, and amyloclastic methods. Despite the presence of numerous methods, there is no general reliable method to assess α-amylase activity. Each method is shown to have its own merits and demerits. Many improvements have been made to make the available methods more accurate, reliable, and easy. This communication briefly discusses the basic reaction mechanisms and critically reviews the advantages and shortcomings associated with each method. Further recommendations are made for future development. © 2020 Society of Chemical Industry     

Effects of subchronic treatment with valproate on L-5-HTP-induced cortisol responses in mania: evidence for increased central serotonergic neurotransmission

The mechanisms underlying the acute and prophylactic antimanic properties of valproate have remained elusive. There are some reports that treatment with valproic acid may increase brain serotonergic neurotransmission in the rodent. This study was carried out in order to investigate the effects of subchronic therapy with valproate on central serotonin metabolism in manic patients. Toward this end, the authors examined plasma cortisol responses to 200 mg (orally) L-5-hydroxy-tryptophan (L-5-HTP) in 10 manic patients both before and after subchronic treatment with valproate. Administration of L-5-HTP resulted in significantly increased cortisol responses both before and after treatment with valproate. The L-5-HTP-induced cortisol responses were significantly higher after treatment with valproate than before treatment. It is suggested that valproate may increase central serotonergic neurotransmission and that this stimulation may play a role in the antimanic effects of valproate.