Cryogel microcarriers for sustained local delivery of growth factors to the brain

Neurotrophic growth factors such as glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) have been considered as potential therapeutic candidates for neurodegenerative disorders due to their important role in modulating the growth and survival of neurons. However, clinical translation remains elusive, as their large size hinders translocation across the blood-brain barrier (BBB), and their short half-life in vivo necessitates repeated administrations. Local delivery to the brain offers a potential route to the target site but requires a suitable drug-delivery system capable of releasing these proteins in a controlled and sustained manner. Herein, we develop a cryogel microcarrier delivery system which takes advantage of the heparin-binding properties of GDNF and BDNF, to reversibly bind/release these growth factors via electrostatic interactions. Droplet microfluidics and subzero temperature polymerization was used to create monodisperse cryogels with varying degrees of negative charge and an average diameter of 20 μm. By tailoring the inclusion of 3-sulfopropyl acrylate (SPA) as a negatively charged moiety, the release duration of these two growth factors could be adjusted to range from weeks to half a year. 80% SPA cryogels and 20% SPA cryogels were selected to load GDNF and BDNF respectively, for the subsequent biological studies. Cell culture studies demonstrated that these cryogel microcarriers were cytocompatible with neuronal and microglial cell lines, as well as primary neural cultures. Furthermore, in vivo studies confirmed their biocompatibility after administration into the brain, as well as their ability to deliver, retain and release GDNF and BDNF in the striatum. Overall, this study highlights the potential of using cryogel microcarriers for long-term delivery of neurotrophic growth factors to the brain for neurodegenerative disorder therapeutics.

Levels of Depression, Anxiety, and Stress Among Saudi Arabia's Medical and Dental Practitioners: A Cross-Sectional Study Following the Covid-19 Pandemic

BACKGROUND Healthcare providers, particularly in dentistry and medicine, experience high stress levels, exacerbated by factors like patient anxiety, clinical work, and continuous training. The COVID-19 pandemic has further increased these risks. This study aimed to assess depression, anxiety, and stress (DAS) among dental and medical practitioners in Saudi Arabia, investigating influential factors on their psychological behavior. MATERIAL AND METHODS In this cross-sectional study conducted in July and August 2021, the depression, anxiety, and stress scale (DASS-21) was administered through a Google questionnaire. Data analysis involved stepwise mode modeling and bivariate analysis, with a significant P value <0.05, using the Statistical Package for the Social Sciences. RESULTS The study included 376 dentists and 201 medical practitioners. Most worked more than four days a week, slept under six hours nightly, and were non-smokers. DAS scores indicated depression (51.7-57.4%), anxiety (50.7-58.2%), and stress (54.2-60.1%). Significant differences (P<0.05) were observed among younger, single, female, and lower-income participants. Higher DAS scores correlated with less sleep, extensive social media use, and smoking history. Socio-demographic factors were mostly non-significant for medical practitioners, except social media use. Sleep duration significantly impacted stress levels, while specialty, income, and marital status influenced depression CONCLUSIONS DAS levels were notably higher in dentists compared to medical practitioners, particularly regarding anxiety. The impact of socioeconomic factors varied, being more statistically significant for dentists.

In the peripheral blood mononuclear cells (PBMCs) of HCV infected patients the expression of STAT1 and IRF-1 is downregulated while that of caspase-3 upregulated

Several peripheral blood mononuclear cell (PBMC) defects have been linked with hepatitis C virus (HCV) infection, including alterations in cytokine secretion and increased cell death. This study was performed to investigate the expression levels of signal transducer and activator of transcription 1 (STAT1), interferon regulatory factor 1 (IRF-1), and caspase 3 in PBMCs of patients infected with HCV. STAT1, IRF-1, and caspase 3 expression levels were compared in PBMCs from 19 untreated (naïve) HCV+ patients, 8 treated (sustained responder [SR]) HCV patients, and 20 HCV- healthy controls. Moreover, PBMCs from naïve HCV+ patients and SR-HCV patients were also evaluated for HCV RNA expression. The expression levels of STAT-1 and IRF-1 were significantly downregulated in PBMCs from naïve HCV+ patients (P  Keywords: PBMC; hepatitis C virus; STAT1; IRF-1; caspase-3.

Growth Factor Therapy for Parkinson's Disease: Alternative Delivery Systems

Despite decades of research and billions in global investment, there remains no preventative or curative treatment for any neurodegenerative condition, including Parkinson's disease (PD). Arguably, the most promising approach for neuroprotection and neurorestoration in PD is using growth factors which can promote the growth and survival of degenerating neurons. However, although neurotrophin therapy may seem like the ideal approach for neurodegenerative disease, the use of growth factors as drugs presents major challenges because of their protein structure which creates serious hurdles related to accessing the brain and specific targeting of affected brain regions. To address these challenges, several different delivery systems have been developed, and two major approaches-direct infusion of the growth factor protein into the target brain region and in vivo gene therapy-have progressed to clinical trials in patients with PD. In addition to these clinically evaluated approaches, a range of other delivery methods are in various degrees of development, each with their own unique potential. This review will give a short overview of some of these alternative delivery systems, with a focus on ex vivo gene therapy and biomaterial-aided protein and gene delivery, and will provide some perspectives on their potential for clinical development and translation.

Psychological impact of the coronavirus disease 2019 (COVID-19) pandemic on dental students: A nationwide study

OBJECTIVES

Public mental health concerns have been raised during the coronavirus disease 2019 (COVID-19) pandemic. The aim of this study was to assess the psychological impact of the pandemic on dental students in Saudi Arabia.

METHODS

A cross-sectional analytical study was conducted among dental students from different universities in Saudi Arabia selected using 2-stage cluster sampling. The psychological impact was assessed using the validated Arabic version of the Depression, Anxiety and Stress Scale-21 Item questionnaire. The data were analyzed using SPSS software. The Mann-Whitney U and Kruskal-Wallis tests were used as appropriate. A chi-squared test was used to compare the proportions between the sociodemographic data and logistic regression analysis to identify variables associated with the student's responses.

RESULTS

The internal consistency of the scale was excellent (0.954). A total of 697 dental students participated voluntarily in the study; their mean age was 21.76 ± 1.859 years, and 54.7% were female. The majority (96.1%) were single, and 69.4% lived in a household of > 5 persons. Significant differences in mental health outcomes were evident for gender, university, and survey time. Elevated levels of depression, anxiety, and stress were recorded among 60.64%, 37.02%, and 34.92%, respectively, of the students. Females, students who lived alone, and junior students were more likely to experience psychological problems during the COVID-19 pandemic.

CONCLUSIONS

The presence of elevated levels of depression, anxiety and stress among dental students highlights the need for psychological empowerment strategies involving institutional counseling services.

Measuring the Kerr nonlinearity via seeded Kerr instability amplification: conceptual analysis

Whereas the Kerr nonlinearity is well understood in the perturbative limit of nonlinear optics, there is considerable discussion about its functional form and magnitude at extreme intensities, at which point matter starts to ionize. Here, we introduce a concept to answer this question and theoretically analyze its feasibility. We demonstrate that seeded Kerr instability amplification provides clear signatures from which functional form and magnitude of the Kerr nonlinearity can be extracted in the non-perturbative limit of nonlinear optics.

Greenhouse gas and ammonia emissions from production of compost bedding on a dairy farm

Recent developments in composting technology enable dairy farms to produce their own bedding from composted manure. This management practice alters the fate of carbon and nitrogen; however, there is little data available documenting how gaseous emissions are impacted. This study measured in-situ emissions of methane (CH₄), carbon dioxide (CO₂), nitrous oxide (N₂O), and ammonia (NH₃) from an on-farm solid-liquid separation system followed by continuously-turned plug-flow composting over three seasons. Emissions were measured separately from the continuously-turned compost phase, and the compost-storage phase prior to the compost being used for cattle bedding. Active composting had low emissions of N₂O and CH₄ with most carbon being emitted as CO₂-C and most N emitted as NH₃-N. Compost storage had higher CH₄ and N₂O emissions than the active phase, while NH₃ was emitted at a lower rate, and CO₂ was similar. Overall, combining both the active composting and storage phases, the mean total emissions were 3.9×10^-2gCH₄kg^-1 raw manure (RM), 11.3gCO₂kg^-1 RM, 2.5×10^-4g N₂O kg^-1 RM, and 0.13g NH₃ kg^-1 RM. Emissions with solid-separation and composting were compared to calculated emissions for a traditional (unseparated) liquid manure storage tank. The total greenhouse gas emissions (CH₄+N₂O) from solid separation, composting, compost storage, and separated liquid storage were reduced substantially on a CO₂-equivalent basis compared to traditional liquid storage. Solid-liquid separation and well-managed composting could mitigate overall greenhouse gas emissions; however, an environmental trade off was that NH₃ was emitted at higher rates from the continuously turned composter than reported values for traditional storage.

Unruptured congenital aneurysm of the left sinus of Valsalva in an adult with complex left heart malformations

A 26 year old man who presented with the first signs of right heart failure was found to have a large congenital aneurysm of the aortic sinus of Valsalva and of the left coronary sinus. These were combined with left heart anomalies in the form of a bicuspid aortic valve, a rare variant of a persistent left superior vena cava with blood flow from the left atrium through the brachiocephalic vein into the superior vena cava and a kink in the aortic arch. An aortic coarctation had been corrected with a patch 12 years earlier. Although the aneurysm was not perforated and there were no clinical signs of infarction, the aneurysm was resected prophylactically and the left coronary artery was reinserted through a bypass with a Gore-Tex conduit. The case is noteworthy because this diagnosis is very rare and its early treatment may prevent several complications. The clinical features, treatment, and outcome are discussed.

Dietary fish oil reduces microvascular thrombosis in a porcine experimental model

Microvascular thrombosis plays a significant role in the pathophysiology of ischaemic reperfusion injury. A fish oil-supplemented diet containing n-3 polyunsaturated fatty acids (PUFA) reduces thromboxane A(2) (TxA(2)) synthesis and, thus, vasoconstriction and platelet aggregation. The aim of this study was to elucidate whether n-3 PUFA in a porcine model of ischaemia and reperfusion injury 1) inhibit accumulation of platelets and fibrinogen in ischaemia-reperfusion injured tissue, 2) prolong the bleeding time, and 3) inhibit TxA(2) synthesis. Nine pigs were fed a standard diet supplemented with 7 g n-3 PUFA/day for 3 weeks. Nine pigs on the standard diet served as controls. Unilateral myocutaneous flaps were exposed to ischaemia for a period of 6 hours. Contralateral flaps were nonischaemic. Tissue contents of radioactive-labelled platelets and fibrinogen were measured after 4 hours of reperfusion. Platelet count, serum TxB(2), and the cutaneous bleeding time were measured before and after 3 weeks of diet. In the fish oil group, the accumulation of platelets was significantly reduced in all the myocutaneous flaps, except in the ischaemic skin part, when compared to control animals. Fibrinogen was significantly reduced in nonischaemic flaps, but not in ischaemic flaps. After the feeding period, the level of TxB(2) was significantly lowered in the fish oil group (p<0.01). No difference in the bleeding time was observed. Thus, dietary supplementation with n-3 PUFA inhibits the formation of microvasculatory thrombosis in this model.

Evaluation of stimulation parameters on aortomyoplasty, using Latissimus Dorsi muscle in a goat model: an acute study

OBJECTIVE

Dynamic aortomyoplasty using Latissimus Dorsi muscle (LDM) has been shown to improve myocardial function. However, systematic examination of the effects of stimulation parameters on aortic wrap function has not been done. Thus, the present study measures the direct effect of stimulation voltage, pulse train duration, frequency of the pulses, and the duration of the stimulation delay from R wave on the aortic wrap function.

METHODS

In eight female goats, the left LDM was wrapped around the descending aorta. The muscle was then subjected to electrical stimulation, altering frequency of stimulation pulses (16.6, 20, 25, 33 and 50 Hz), amplitude (2, 4, 6, 8 and 10 V), and number of pulses (2, 4, 6, 8 and 10 pulses) in a train stimulation. Left ventricular, aortic pressure, and pressure generated by LDM on aorta (wrap pressure) was measured. The changes in hemodynamic parameters mentioned above were calculated and compared for different stimulation parameters during unassisted and assisted cardiac cycles.

RESULTS

Aortomyoplasty counterpulsation using LDM provided significant improvement in wrap pressure (78 mmHg +/- 2), aortic diastolic pressure, and changes in aortic diastolic pressure from 2 to 4 V (P < 0.05). Further increase in amplitude did not make any significant improvements of the above mentioned parameters. Significant augmentation of wrap pressure (82 mmHg +/- 2), aortic diastolic pressure (79 mmHg +/- 3) and changes in aortic diastolic pressure (12 mmHg +/- 1) occurred at 6 pulses (P < 0.05). Other changes in number of pulses did not show any significant improvements. Significant improvement of wrap pressure (80 mmHg +/- 2), aortic diastolic pressure (73 mmHg +/- 3) and changes in aortic diastolic pressure (12 mmHg +/- 1) was observed with a frequency of 33 Hz. To examine a wide range of delays from the onset of the QRS complex to LDM stimulation, stimulation was delivered randomly. The exact delay was determined from the ECG signal and superimposed LDM stimulation pulses.

CONCLUSIONS

In this study we present a new measurement, wrap pressure. We also present that in aortomyoplasty using LDM, the most significant improvement in wrap pressure, aortic diastolic pressure and changes in aortic diastolic pressure occurs when the stimulation consists of an amplitude of 4 V, a frequency of 33 Hz and a train stimulation of 6 pulses.