Since the pandemic of COVID-19 has intensely struck human society, small animal model for this infectious disease is in urgent need for basic and pharmaceutical research. Although several COVID-19 ...animal models have been identified, many of them show either minimal or inadequate pathophysiology after SARS-CoV-2 challenge. Here, we describe a new and versatile strategy to rapidly establish a mouse model for emerging infectious diseases in one month by multi-route, multi-serotype transduction with recombinant adeno-associated virus (AAV) vectors expressing viral receptor. In this study, the proposed approach enables profound and enduring systemic expression of SARS-CoV-2-receptor hACE2 in wild-type mice and renders them vulnerable to SARS-CoV-2 infection. Upon virus challenge, generated AAV/hACE2 mice showed pathophysiology closely mimicking the patients with severe COVID-19. The efficacy of a novel therapeutic antibody cocktail RBD-chAbs for COVID-19 was tested and confirmed by using this AAV/hACE2 mouse model, further demonstrating its successful application in drug development.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Picophytoplankton are the smallest, most abundant photosynthetic organisms in the ocean. Knowledge of the diel variability of these tiny microbes has important implications for the structure of ...microbial food webs and key biogeochemical processes. However, insight into the mechanisms that underlie picophytoplanktonic diel dynamics is limited. By combining a field survey with a published dataset, we found that cell numbers and cell sizes/biomasses of picophytoplankton were tightly synchronized to the day‐night cycle, but they were in a quasi‐antiphase relationship to each other. This pattern is a confirmation and extension of previous studies. Mortality rates showed that Prochlorococcus and Synechococcus were subject to considerable grazing pressure throughout the day and night. The quasi‐antiphase diel cycles in abundance and cell size/biomass are likely determined by the light‐dependent diel behavior of cell growth and division and continuous losses to grazing. This work significantly improves our understanding of autotrophic picoplankton in the oligotrophic ocean.
Plain Language Summary
Picophytoplankton are tiny, single‐celled photosynthetic organisms that contribute to almost all primary production in the vast euphotic zones of the oligotrophic ocean. Understanding their roles in that environment is critical but challenging, mainly because of their minuscule size and the complexity of microbial processes and interactions. Time‐series observations based on flow cytometry, a powerful technique that provides information about the numbers and sizes of picophytoplankton cells, have elucidated many ecological and biogeochemical processes associated with picophytoplankton, but some questions remain. A field survey in the northern South China Sea combined with a published dataset revealed that picophytoplankton cell size and biomass tended to decrease (increase) during the night (day) when cell numbers were increasing (decreasing). Such quasi‐antiphase cycles are likely a general feature of near‐steady‐state oligotrophic ecosystems and reflect the cycles of carbon fixation, energy storage, and cell growth during the daytime and cell division and energy depletion during the night. Mortality rates estimated via modified dilution experiments showed that Prochlorococcus and Synechococcus were subject to considerable grazing pressure throughout the day and night. This work significantly improves our understanding of these microorganisms and may have implications for the carbon cycle in oligotrophic marine ecosystems.
Key Points
Picophytoplanktonic quasi‐antiphase diel cycles in abundance and cell size/biomass are likely a general feature of the oligotrophic ocean
Grazing pressure on Prochlorococcus and Synechococcus is as high during the day as during the night
This study aims to investigate the relative importance of nanoflagellate grazing and viral lysis for heterotrophic bacteria and Synechococcus spp. mortality in coastal waters of the north-eastern ...Taiwan. The results showed that viral lysis and nanoflagellate grazing are the main factors responsible for the mortality of heterotrophic bacteria, however, the presence of viruses had a positive effect on the Synechococcus spp. growth. Moreover, this study observed different growth responses between heterotrophic bacteria and Synechococcus spp. population by using the modified dilution approach. The results also showed that there was lower net growth rate of Synechococcus spp. in 30 kDa dilution series than that observed in 0.2 μm series. Furthermore, based on the results obtained from modified dilution approach, we can estimate that about 12.8 ng N L^(-1) h^(-1) and 2.8 ng P L^(-1) h^(-1) was released by nanoflagellate grazing. In addition, this study estimated that, during the process of viral lysis, locally recycled nutrients released about 224 ng N L^(-1) h^(-1) and 24.9 ng P L^(-1) h^(-1) in this system. Our findings suggest that due to viral lysis, substantial portion of the recycled nutrients required for Synechococcus spp. growth was supplied sufficiently, emphasizing the importance of the viral shunt, especially in oligotrophic regions.
Mutations in genes involved in the production, migration, or differentiation of cortical neurons often lead to malformations of cortical development (MCDs). However, many genetic mutations involved ...in MCD pathogenesis remain unidentified. Here we developed a genetic screening paradigm based on transposon-mediated somatic mutagenesis by in utero electroporation and the inability of mutant neuronal precursors to migrate to the cortex and identified 33 candidate MCD genes. Consistent with the screen, several genes have already been implicated in neural development and disorders. Functional disruption of the candidate genes by RNAi or CRISPR/Cas9 causes altered neuronal distributions that resemble human cortical dysplasia. To verify potential clinical relevance of these candidate genes, we analyzed somatic mutations in brain tissue from patients with focal cortical dysplasia and found that mutations are enriched in these candidate genes. These results demonstrate that this approach is able to identify potential mouse genes involved in cortical development and MCD pathogenesis.
ᴅ-cycloserine (DCS), an FDA-approved medicine for the treatment of tuberculosis, is also a partial agonist at the glycine recognition site of
-methyl-ᴅ-aspartate (NMDA) receptor and has shown ...significant treatment efficacy for central nervous system (CNS) disorders including depression, schizophrenia, Alzheimer's disease, and post-traumatic stress disorder. The physicochemical properties of DCS, however, limit the options of formulation and medicinal applications of DCS, and warrants further investigation for the development of CNS therapeutics. Nanocrystals play an important role in pharmaceutic design and development. The properties of nanocrystals are remarkably different from their bulk material counterpart, attributed to the large surface-area-to-volume ratio which can improve the bioavailability. In this study, for the first time, DCS, a highly water-soluble compound, has formed nanocrystals and this was confirmed by scanning electronic microscopy and X-ray powder diffraction. Furthermore, DCS nanocrystals were applied to several formulations to test their stability and then to the in vitro Franz diffusion test with reservoir patch formulation as well as in vivo pharmacokinetics study with enteric capsules. We tested these formulations regarding their nanocrystal physical properties, size effect, and dissolution rate, respectively. We found that DCS nanocrystals showed good performance in the Franz diffusion test and rodent pharmacokinetic studies due to the nanoparticle size and faster dissolution as compared with the commercial DCS powder. These DCS nanocrystal formulations could offer a new approach for the development of an advanced drug delivery system for the treatment of CNS disorders.
As important bacterivores in planktonic food webs, mixotrophic nanoflagellates cancause mortality in marine Synechococcus spp. Our previous study found that the pigmented nanoflagellate (PNF) has a ...significant grazing impact on Synechococcus spp. In the current study, we applied the dilution approach to test the growth and grazing rates of nanoflagellates on Synechococcus spp. We then compared the differences between experimental nutrient additions and in situ conditions in the coastal waters of the East China Sea during the summer season from July to September. The growth rates of Synechococcus spp. in the ambient environment were between 0.54 and 0.62 day−1, which were slightly higher than the 0.56 and 0.66 day−1 with nutrient enrichment in summer. In contrast, our nutrient enrichment experiments produced a marked decline approximately from 21% to 58% in the nanoflagellate grazing rate on Synechococcus spp. The reason was that the mixotrophic PNFs directly used the added nutrients and reduced their supply of nutrients from prey during the incubation experiments.
It is crucial to regulate N-methyl-D-aspartate (NMDA) function bivalently depending on the central nervous system (CNS) conditions. CNS disorders with NMDA hyperfunction are involved in the ...pathogenesis of neurotoxic and/or neurodegenerative disorders with elevated D-serine, one of the NMDA receptor co-agonists. On the contrary, NMDA-enhancing agents have been demonstrated to improve psychotic symptoms and cognition in CNS disorders with NMDA hypofunction. Serine racemase (SR), the enzyme regulating both D- and L-serine levels through both racemization (catalysis from L-serine to D-serine) and β-elimination (degradation of both D- and L-serine), emerges as a promising target for bidirectional regulation of NMDA function. In this study, we explored using dimethyl malonate (DMM), a pro-drug of the SR inhibitor malonate, to modulate NMDA activity in C57BL/6J male mice via intravenous administration. Unexpectedly, 400 mg/kg DMM significantly elevated, rather than decreased (as a racemization inhibitor), D-serine levels in the cerebral cortex and plasma. This outcome prompted us to investigate the regulatory effects of dodecagalloyl-α-D-xylose (α12G), a synthesized tannic acid analog, on SR activity. Our findings showed that α12G enhanced the racemization activity of human SR by about 8-fold. The simulated and fluorescent assay of binding affinity suggested a noncooperative binding close to the catalytic residues, Lys56 and Ser84. Moreover, α12G treatment can improve behaviors associated with major CNS disorders with NMDA hypofunction including hyperactivity, prepulse inhibition deficit, and memory impairment in animal models of positive symptoms and cognitive impairment of psychosis. In sum, our findings suggested α12G is a potential therapeutic for treating CNS disorders with NMDA hypofunction.
A 66-year-old female patient was brought to the emergency department (ED) of our hospital. The pathological features show hyperplastic gastric folds involving mainly the body and fundus with ...irregular, tortuous, cystically dilated, and elongated foveolar epithelium, and the mucosal surface showed edema, capillary congestion and chronic inflammatory infiltration. 4 The patient can be treated medically firstly, with treatments such as high-protein diet, proton pump inhibitors, eradication of H.P. or cytomegalovirus and octreotide long-acting release, and even the epidermal growth factor receptor inhibitor, cetuximab. CONFLICT OF INTEREST STATEMENT All authors declare no conflict of interest.
T helper (Th)2 cytokines such as interleukin (IL)-4 and IL-13 control immune function by acting on leukocytes. They also regulate multiple responses in non-hematopoietic cells. During pregnancy, IL-4 ...and IL-13 facilitate alveologenesis of mammary glands. This particular morphogenesis generates alveoli from existing ducts and requires substantial cell proliferation. Using 3D cultures of primary mouse mammary epithelial cells, we demonstrate that IL-4 and IL-13 promote cell proliferation, leading to enlargement of mammary acini with partially filled lumens. The mitogenic effects of IL-4 and IL-13 are mediated by STAT6 as inhibition of STAT6 suppresses cell proliferation and improves lumen formation. In addition, IL-4 and IL-13 stimulate tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1). Prolonged treatment with these cytokines leads to increased IRS-1 abundance, which, in turn, amplifies IL-4- and IL-13-stimulated IRS-1 tyrosine phosphorylation. Through signaling crosstalk between IL-4/IL-13 and insulin, a hormone routinely included in mammary cultures, IRS-1 tyrosine phosphorylation is further enhanced. Lowering IRS-1 expression reduces cell proliferation, suggesting that IRS-1 is involved in IL-4- and IL-13-stimulated cell proliferation. Thus, a Th2-dominant cytokine milieu during pregnancy confers mammary gland development by promoting cell proliferation.
Background and Aim
Intragastric botulinum toxin A (BTA) injection is a potential treatment for weight reduction in obese patients. Current studies yielded conflicting results. We performed a ...systematic review and meta‐analysis of randomized controlled trials (RCTs) to assess the efficacy of intragastric BTA injection for weight management.
Methods
We searched several databases to identify RCTs evaluating intragastric BTA injections for obesity. We applied random‐effects models for all meta‐analyses due to heterogeneity in the included studies. The mean difference (MD) and 95% confidence interval (CI) were calculated for continuous outcomes.
Results
A total of 6 RCTs including 192 subjects met the inclusion criteria and were included for the meta‐analysis. Although the pooled data from six studies showed no difference in the absolute weight loss between intragastric BTA injection and control, subgroup analysis showed a significantly decreased absolute weight after a BTA injection dose ≥ 200 U (MD, −2.04 kg; 95% CI, −3.96 to −0.12) and after multiple injection regions in the stomach combined with diet control (MD, −4.44 kg; 95% CI, −6.54 to −2.33 kg) compared with the control. Regarding absolute weight loss, the impact of endoscopic ultrasound‐guided injection and follow‐up duration showed no difference. Intragastric BTA injection had a significant change in body mass index (MD, −1.25 kg/m2; 95% CI, −2.18 to −0.32 kg/m2) and prolonged gastric half‐emptying time (MD, 11.37 min; 95% CI, −3.69 to 19.06 min).
Conclusion
Intragastric BTA injection is effective for obesity treatment, and adequate doses (≥ 200 U), multiple gastric injection regions, and combined diet control are crucial. However, given the small sample size and limited power, caution should be exercised.
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