316 research outputs found
An Investigation on the antimicrobial activity of some endemic plant species from Turkey
In this study performed on six endemic plant species, antimicrobial activity was observed in Campanula lyrata subsp.lyrata and Abies nordmanniana subsp. bornmuelleriana plants. The minimum inhibitoryconcentration of C. lyrata subsp. lyrata (leaf and flower) extract was found to be 29 mg/ml for Baccillus subtilis and 14.5 mg/ml for Staphylococcus aureus, and the minimum inhibitory concentration (MIC) of Abies nordmanniana subsp. bornmuelleriana (leaf) extract was found to be > 314 mg/ml for B. subtilis and when minimum bacteriocidal concentration (MBC) results were evaluated, it was observed that the plant extracts had bacteriocidal effects. No antimicrobial activity was observed inthe other plant extracts, namely, Onosma bornmuelleri (leaf- flower), Dianthus balansae (leaf- flower), Alyssum pateri subsp. pateri (seed) and Scabiosa columbaria subsp. paphlagonica (leaf) extracts thatwere tested
Effects of treatment with chitosan on sensory and chemical quality parameters of frozen shrimp
Unusual cause of a painful right testicle in a 16-year-old man: a case report
<p>Abstract</p> <p>Introduction</p> <p>Urgent surgical exploration of the scrotum of a child or teenager who presents with a painful and swollen testicle is paramount if testicular torsion is not to be missed. It is extremely rare for a non-scrotal pathology to present with acute scrotal signs. Here we present such a rare case and emphasize the importance of being aware of this potential clinical pitfall.</p> <p>Case presentation</p> <p>A 16-year-old Caucasian man presented as a surgical emergency with a five to six hour history of a painful, red, and swollen right hemiscrotum. He also complained of vague lower abdominal pain, vomiting, and watery diarrhea. He had a temperature of 38.5°C and a tender, red, and swollen right hemiscrotum. The right testicle appeared elevated. He was mildly tender in his central and upper abdomen and less so in the lower abdomen. No convincing localizing abdominal signs were noted. He had an increased white cell count (15 × 10<sup>9</sup>/L) and C-reactive protein (CRP; 300 mg/L). Urgent right hemiscrotal exploration revealed about 5 ml of pus in the tunica vaginalis and a normal testicle. A right iliac fossa incision identified the cause: a perforated retrocecal appendix. Appendectomy was performed, and both the abdomen and scrotum washed copiously with saline before closure. The patient made an uneventful recovery.</p> <p>Conclusion</p> <p>Acute appendicitis presenting with scrotal signs due to a patent processus vaginalis is an extremely rare clinical entity. To date, fewer than five such cases have been reported in the medical literature. It is, therefore, extremely important to be aware of this unusual clinical scenario, as only a high index of suspicion will enable prompt, successful management of both the appendicitis and the scrotal abscess.</p
Activity Dependent Protein Degradation Is Critical for the Formation and Stability of Fear Memory in the Amygdala
Protein degradation through the ubiquitin-proteasome system [UPS] plays a critical role in some forms of synaptic plasticity. However, its role in memory formation in the amygdala, a site critical for the formation of fear memories, currently remains unknown. Here we provide the first evidence that protein degradation through the UPS is critically engaged at amygdala synapses during memory formation and retrieval. Fear conditioning results in NMDA-dependent increases in degradation-specific polyubiquitination in the amygdala, targeting proteins involved in translational control and synaptic structure and blocking the degradation of these proteins significantly impairs long-term memory. Furthermore, retrieval of fear memory results in a second wave of NMDA-dependent polyubiquitination that targets proteins involved in translational silencing and synaptic structure and is critical for memory updating following recall. These results indicate that UPS-mediated protein degradation is a major regulator of synaptic plasticity necessary for the formation and stability of long-term memories at amygdala synapses
NMR and in silico studies of fucosylated chondroitin sulfate (fCS) and its interactions with selectins
This thesis describes structural studies on the interactions between the fucosylated
chondroitin sulfate (fCS) oligosaccharides and human proteins known as selectins. fCS is a
carbohydrate obtained from sea cucumbers, that can be classified as a branched
glycosaminoglycan (GAG). It has attracted much attention due to its anti-coagulant, anti-inflammatory,
antimetastatic and anti-HIV properties and its structure was previously
determined by NMR. Selectins constitute a family of proteins involved in cell adhesion
processes, such as inflammation, attachment of viral particles and migration of tumour cells.
fCS oligosaccharides have been shown to bind to selectins, which is likely a reason behind
their biological activity. However, the mechanism of this interaction is currently unknown.
The initial part of the thesis describes the experimental work on expression and purification
of the recombinant L- and P-selectin constructs in Pichia pastoris, Escherichia coli and HEK
293 cells. The aim of these experiments was to produce two constructs for each selectin, a
single domain construct, consisting of the C-type lectin domain only, and a double domain
construct, consisting of both the C-type lectin and the EGF-like domains. The intention was
that the recombinant proteins would be labelled with 13C and 15N to allow for the in-depth
structural NMR studies on the fCS-selectin interaction. Various experimental approaches
have been explored, including the use of different cell lines, modifications to construct design,
as well as alterations to expression and purification conditions. Although it was not possible
to produce soluble selectin constructs in either bacterial or yeast cells, protein expression
tests in HEK293 cells, performed in collaboration with the Oxford Protein Production facility
(OPPF), led to production of a soluble L-selectin construct, consisting of the L-selectin C-type
lectin domain.
The produced L-selectin construct, as well as two commercially available constructs of the Land
P-selectin extracellular domains, were used in the Saturation Transfer Difference (STD)
NMR experiments to provide new information about the nature of the fCS-selectin binding.
The STD experiments allowed to identify the regions within the fCS oligosaccharides that are
in direct contact with the protein and likely play an important role in this interaction.
Experiments on different protein constructs allowed the comparison of fCS binding to P-selectin
and to two different recombinant constructs of L-selectin. Results of these studies
suggest that the binding occurs via a similar mechanism for both L- and P-selectins and that
the fCS oligosaccharides bind to one-domain L-selectin construct with similar affinity as to a
larger construct, consisting of the entire extracellular region of the protein.
Alongside the experimental work, theoretical in silico studies on the fCS-selectin binding
were undertaken as part of this project. The existing X-ray structures of selectin complexes
were subjected to Molecular Dynamics (MD) simulations, which allowed to explore the
dynamic behaviour of E-selectin upon binding to sialyl Lewis x (sLex). It was found that sLex
forms a more favourable interaction with the extended conformation of E-selectin and that
the protein in this conformation is characterised by a high degree of interdomain flexibility,
with a new type of interdomain movement observed in the MD studies on this complex.
In further in silico studies, the fCS oligosaccharides were docked to the existing P-selectin
structures. The docking tests were performed on the computationally produced fCS
trisaccharides with fucose branches either 2,4 or 3,4-sulfated. Results were evaluated with
MD simulations and analysed in the light of current knowledge of selectin-ligand binding and
the STD NMR experimental results. The in silico studies allowed to identify a subset of P-selectin
residues that are likely involved in the interaction with fCS oligosaccharides in vivo.
The conformational behaviour of P-selectin upon binding to fCS was also explored and it was
found that the interdomain hinge is flexible during this interaction and allows transition from
bent to extended conformational state.
Finally, a new NMR method was developed to facilitate the studies of complex carbohydrates,
incorporating the concepts of G-matrix Fourier Transform (GFT) NMR into 2D HSQC and 2D
HSQC-TOCSY experiments. The method allows to separate peaks in the regions of high
spectral overlap, providing information that can simplify the assignment process. The new
experiments facilitated the structural evaluation of a sample containing a mixture of
oligosaccharides resulting from the depolymerisation of fCS polysaccharide
Reversible Keap1 inhibitors are preferential pharmacological tools to modulate cellular mitophagy
Mitophagy orchestrates the autophagic degradation of dysfunctional mitochondria preventing their pathological accumulation and contributing to cellular homeostasis. We previously identified a novel chemical tool (hereafter referred to as PMI), which drives mitochondria into autophagy without collapsing their membrane potential (ΔΨm). PMI is an inhibitor of the protein-protein interaction (PPI) between the transcription factor Nrf2 and its negative regulator, Keap1 and is able to up-regulate the expression of autophagy-associated proteins, including p62/SQSTM1. Here we show that PMI promotes mitochondrial respiration, leading to a superoxide-dependent activation of mitophagy. Structurally distinct Keap1-Nrf2 PPI inhibitors promote mitochondrial turnover, while covalent Keap1 modifiers, including sulforaphane (SFN) and dimethyl fumarate (DMF), are unable to induce a similar response. Additionally, we demonstrate that SFN reverses the effects of PMI in co-treated cells by reducing the accumulation of p62 in mitochondria and subsequently limiting their autophagic degradation. This study highlights the unique features of Keap1-Nrf2 PPI inhibitors as inducers of mitophagy and their potential as pharmacological agents for the treatment of pathological conditions characterized by impaired mitochondrial quality control
Primary tracheal adenocystic carcinoma and tracheal tumors during pregnancy
Cancer complicates approximately 0.1% of all pregnancies. Primary tracheal carcinoma is one of very rarely seen tumors and the rate of its being seen makes up approximately % 0.2 of all tumors of respiratory tract. The patient, 28 years old, who has 28-weeks-pregnant, was diagnosed with primary tracheal adenocystic carcinoma. Patient was made operation as thoracotomy and tracheal tumor was removed at the 28th week of pregnancy. Patient was delivered with sectio abdominale at the 39th week of pregnancy. Primary tracheal adenocystic carcinoma is very rarely seen tumors and it is the first tracheal ACC with pregnancy case in literature to have been detected and surgically treated during pregnancy. We discussed primary tracheal adenocystic carcinoma and tracheal tumors during pregnancy with literature
The pharmacological regulation of cellular mitophagy
Small molecules are pharmacological tools of considerable value for dissecting complex biological processes and identifying potential therapeutic interventions. Recently, the cellular quality-control process of mitophagy has attracted considerable research interest; however, the limited availability of suitable chemical probes has restricted our understanding of the molecular mechanisms involved. Current approaches to initiate mitophagy include acute dissipation of the mitochondrial membrane potential (ΔΨm) by mitochondrial uncouplers (for example, FCCP/CCCP) and the use of antimycin A and oligomycin to impair respiration. Both approaches impair mitochondrial homeostasis and therefore limit the scope for dissection of subtle, bioenergy-related regulatory phenomena. Recently, novel mitophagy activators acting independently of the respiration collapse have been reported, offering new opportunities to understand the process and potential for therapeutic exploitation. We have summarized the current status of mitophagy modulators and analyzed the available chemical tools, commenting on their advantages, limitations and current applications
In silico Identification and Expression of Protocadherin Gene Family in Octopus vulgaris
Connecting millions of neurons to create a functional neural circuit is a daunting challenge. Vertebrates developed a molecular system at the cell membrane to allow neurons to recognize each other by distinguishing self from non-self through homophilic protocadherin interactions. In mammals, the protocadherin gene family counts about 50 different genes. By hetero-multimerization, protocadherins are capable of generating an impressive number of molecular interfaces. Surprisingly, in the California two-spot octopus, Octopus bimaculoides, an invertebrate belonging to the Phylum Mollusca, over 160 protocadherins (PCDHs) have been identified. Here we briefly discuss the role of PCDHs in neural wiring and conduct a comparative study of the protocadherin gene family in two closely related octopus species, Octopus vulgaris and O. bimaculoides. A first glance at the expression patterns of protocadherins in O. vulgaris is also provided. Finally, we comment on PCDH evolution in the light of invertebrate nervous system plasticity
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