CREB-Regulated Transcriptional Coactivator 2 Proteome Landscape is Modulated by SREBF1

cAMP response element-binding protein (CREB) regulated transcriptional coactivator 2 (CRTC2) is a critical transcription factor that maintains glucose homeostasis by activating CREB. Energy homeostasis is maintained through multiple pathways; therefore, CRTC2 may interact with other transcription factors, particularly under metabolic stress. CRTC2 liver-specific KO mice were created, and the global proteome, phosphoproteome, and acetylome from liver tissue under high-fat diet conditions were analyzed using liquid chromatography-tandem mass spectrometry and bioinformatics analysis. Differentially regulated proteins (DRPs) were enriched in metabolic pathways, which were subsequently corroborated through animal experiments. The consensus DRPs from these datasets were used as seed proteins to generate a protein-protein interaction network using STRING, and GeneMANIA identified fatty acid synthase as a mutually relevant protein. In an additional local-protein-protein interaction analysis of CRTC2 and fatty acid synthase with DRPs, sterol regulatory element binding transcription factor 1 (SREBF1) was the common mediator. CRTC2-CREB and SREBF1 are transcription factors, and DNA-binding motif analysis showed that multiple CRTC2-CREB-regulated genes possess SREBF1-binding motifs. This indicates the possible induction by the CRTC2-SREBF1 complex, which is validated through luciferase assay. Therefore, the CRTC2-SREBF1 complex potentially modulates the transcription of multiple proteins that fine-tune cellular metabolism under metabolic stress.

Knowledge, Attitude and Practice of Undergraduate Medical Students of Bangladesh Regarding COVID-19 and its Vaccination

Medical students are one of the socially active, reliable, and persuading population of information, prevention and control, and incentive of vaccination to stop the current pandemic situation. Consequently, knowing the status of medical students' knowledge, about symptoms, and transmission of disease, prevention of COVID-19 and their attitudes towards a vaccine is important. This multi-center cross-sectional descriptive study was one of the first ones in Bangladesh among the undergraduate medical students who completed pathology, microbiology, and pharmacology. The study was conducted from March to April 2021, using a convenience sampling method in twelve government and non-government medical colleges. Among 1132 who completed the questionnaire, and 15 students from different centers were excluded from the pre-testing and face validation. The age of the 1117 respondents were 22 to 23 years, of which the majority of the respondents were female 749 (67.0%), and 368 (33.0%) were male. Almost all participants had correct knowledge (84.1%) about the symptoms of COVID-19. But 59.2% had wrong knowledge about transmission of disease by an afebrile person. Above 60.0 % of the participants have worn a facial mask when contacting people, refrained from shaking hands, washed hands, avoided people with signs and symptoms suggestive of COVID-19, and avoided crowded places as a practice of prevention. 37.6% of medical students showed positive attitudes about the participation of management of a COVID-19 patient. Most of the participants' decided to have a vaccine depending on its availability. But 31.5% had trust in natural immunity rather than vaccination. Most undergraduate Medical college students understood the basic information, possessed a positive attitude, and presented good practice towards the COVID-19 and vaccination. They play a crucial role in motivation and acceptance of vaccines among the general citizen to fight back against the pandemic in the country with limited resources.

Physical, Psychological and Social Impact of COVID-19 Pandemic on Healthcare Workers at a COVID Designated Bangladeshi Public Hospital

The world has been devastated facing the outbreak of a novel infectious disease known as Corona virus disease (COVID-19). This has been declared as a pandemic by the World Health Organization. The frontline health care workers, who are directly involved in the diagnosis, treatment and care of patients with COVID-19, are taking significant personal risks on their own health and those of their family members. Objectives of the study include establishing the physical, psychological and social impact experience by the healthcare workers serving in public hospitals of Bangladesh. This prospective cross-sectional observational study was carried out at Kuwait Bangladesh Friendship Government Hospital, the first Covid-19 designated hospital of Bangladesh between the 1st June and the 31st August, 2020. A total of 294 doctors, nurses, ward boys and ailed healthcare workers were included in this study via purposive sampling. The study found statistically significant (p value 0.024) difference of medical co-morbidities between Covid-19 positive and Covid-19 negative groups of health care professionals. Significant association was found between duration of work and presence during aerosol generating procedure with COVID infectivity of the study subjects. 72.8% respondents experienced public fear of contracting the virus from them and 69.0% noticed negative attitude of the society towards them. Eighty five percent (85.0%) did not get any community support during this pandemic crisis. The health care professionals engaged in COVID-19 treatment have been taking significant personal risk on their life in terms of physical, psychological and social perspective. Providing safeguard to the health care workers are integral components of public health measures for addressing the COVID-19 pandemic. Special interventions to promote their physical wellbeing and arrangement of adequate psychological training need to be immediately implemented to cope up this critical situation.

Lipid kinase PIP5Kα contributes to Hippo pathway activation via interaction with Merlin and by mediating plasma membrane targeting of LATS1

BACKGROUND

The Hippo pathway plays a critical role in controlled cell proliferation. The tumor suppressor Merlin and large tumor suppressor kinase 1 (LATS1) mediate activation of Hippo pathway, consequently inhibiting the primary effectors, Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ). Phosphatidylinositol 4,5-bisphosphate (PIP2), a lipid present in the plasma membrane (PM), binds to and activates Merlin. Phosphatidylinositol 4-phosphate 5-kinase α (PIP5Kα) is an enzyme responsible for PIP2 production. However, the functional role of PIP5Kα in regulation of Merlin and LATS1 under Hippo signaling conditions remains unclear.

METHODS

PIP5Kα, Merlin, or LATS1 knockout or knockdown cells and transfected cells with them were used. LATS1, YAP, and TAZ activities were measured using biochemical methods and PIP2 levels were evaluated using cell imaging. Low/high cell density and serum starvation/stimulation conditions were tested. Colocalization of PIP5Kα and PIP2 with Merlin and LATS1, and their protein interactions were examined using transfection, confocal imaging, immunoprecipitation, western blotting, and/or pull-down experiments. Colony formation and adipocyte differentiation assays were performed.

RESULTS

We found that PIP5Kα induced LATS1 activation and YAP/TAZ inhibition in a kinase activity-dependent manner. Consistent with these findings, PIP5Kα suppressed cell proliferation and enhanced adipocyte differentiation of mesenchymal stem cells. Moreover, PIP5Kα protein stability and PIP2 levels were elevated at high cell density compared with those at low cell density, and both PIP2 and YAP phosphorylation levels initially declined, then recovered upon serum stimulation. Under these conditions, YAP/TAZ activity was aberrantly regulated by PIP5Kα deficiency. Mechanistically, either Merlin deficiency or LATS1 deficiency abrogated PIP5Kα-mediated YAP/TAZ inactivation. Additionally, the catalytic domain of PIP5Kα directly interacted with the band 4.1/ezrin/radixin/moesin domain of Merlin, and this interaction reinforced interaction of Merlin with LATS1. In accordance with these findings, PIP5Kα and PIP2 colocalized with Merlin and LATS1 in the PM. In PIP5Kα-deficient cells, Merlin colocalization with PIP2 was reduced, and LATS1 solubility increased.

CONCLUSIONS

Collectively, our results support that PIP5Kα serves as an activator of the Hippo pathway through interaction and colocalization with Merlin, which promotes PIP2-dependent Merlin activation and induces local recruitment of LATS1 to the PIP2-rich PM and its activation, thereby negatively regulating YAP/TAZ activity. Video Abstract.

Association of BUD13-ZNF259-APOA5-APOA1-SIK3 cluster polymorphism in 11q23.3 and structure of APOA5 with increased plasma triglyceride levels in a Korean population

In this association study on chromosome 11, the data from 12,537 Korean individuals within the Health Examinee (HEXA) and the Korea Association Resource (KARE) projects were analysed to identify genetic loci correlating with increased and decreased plasma triglyceride (TG) levels. We identified a locus in chromosomal region 11q23.3 that harbours genes BUD13, ZNF259, APOA5, APOA1, and SIK3, which may be associated with plasma TG levels. In this locus, 13 relevant single-nucleotide polymorphisms (SNPs) were found: rs184616707, rs118175510, rs60954647, rs79408961, and rs180373 (near BUD13); rs11604424 (in ZNF259); rs2075291, rs651821, and rs7123666 (in or near APOA5); rs525028 (near APOA1), and rs645258, rs10160754, and rs142395187 (in or near SIK3). All 13 SNPs satisfied the genome-wide significance level (P < 5.0 × 10^-8) in both meta-analysis and conditional analysis. Haplotype analysis of six SNPs (rs79408961, rs180373, rs2075291, rs651821, rs525028, and rs10160754) that were selected based on the β coefficient and conditional P values, revealed nine common haplotypes (with frequency 0.02-0.34) associated with both increased and reduced TG levels. Furthermore, to shed light on possible structural implications, we modelled and simulated the G185C variant of APOA5 (corresponding to rs2075291), which showed the strongest association. Molecular dynamics simulation results showed that this polymorphic variant of APOA5 has a different hydrogen bond network, increased average distance between chains, and an ability to form distinct clusters. Owing to the orientation of cysteine, the possibility of disulphide bond formation with other proteins is evident. In summary, our association and modelling analyses provided evidence that genetic variations in chromosomal region 11q23.3 are associated with elevated TG levels.

Structural mechanism of DNA-mediated Nanog–Sox2 cooperative interaction

The efficiency of stem cell transcriptional regulation always depends on the cooperative association and expression of transcription factors (TFs). Among these, Oct4, Sox2, and Nanog play major roles. Their cooperativity is facilitated via direct protein–protein interactions or DNA-mediated interactions, yet the mechanism is not clear. Most biochemical studies have examined Oct4/Sox2 cooperativity, whereas few studies have evaluated how Nanog competes in the connection between these TFs. In this study, using computational models and molecular dynamics simulations, we built a framework representing the DNA-mediated cooperative interaction between Nanog and Sox2 and analyzed the plausible interaction factors experienced by Nanog because of Sox2, its cooperative binding partner. Comparison of a wild-type and mutant Nanog/Sox2 model with the Nanog crystal structure revealed the regulatory structural mechanism between Nanog/Sox2–DNA-mediated cooperative bindings. Along with the transactivation domains interaction, the DNA-mediated allosteric interactions are also necessary for Nanog cooperative binding. DNA-mediated Nanog–Sox2 cooperativity influences the protein conformational changes and a stronger interaction profile was observed for Nanog-Mut (L103E) in comparison with the Nanog-WT complex.

The efficiency of stem cell transcriptional regulation always depends on the cooperative association and expression of transcription factors (TFs).

Effectiveness of fascial closure technique following percutaneous endovascular aneurysm repair

INTRODUCTION

Percutaneous access and closure is commonly performed for patients undergoing endovascular aneurysm repair (EVAR). It has proven to be a safe and successful method of closure associated with fewer complications when compared with the traditional open technique. Fascial closure is an alternative technique that can be used for closure reducing the risks associated with the open technique. The aim of this study was to assess the safety and durability of fascial closure for failed percutaneous closure device following EVAR.

MATERIALS AND METHODS

Over a 12-month period, 49 patients who had undergone EVAR were identified via our EVAR register. Retrospective analysis of the clinical records was undertaken. We identified all the patients who had fascial closure of the groins following a failed percutaneous closure device. Patients had a computed tomography angiogram one month postoperatively, with duplex imaging and clinic follow-up three months later.

RESULTS

Fascial closure was performed in 14 groins. It failed in three groins and these patients had traditional open repair. Fascial closure was successful in 11 groins (7 patients). Of these seven patients, one was female (6%). The mean age was 80 years (range 68-92 years). Two patients died and one was lost to follow-up. One pseudoaneurysms were seen on computed tomography angiogram, which was managed conservatively and had resolved on follow-up imaging.

CONCLUSIONS

Fascial closure is a very good alternative to open repair after failure of the closure device.

Molecular Interactions Between Innate and Adaptive Immune Cells in Chronic Lymphocytic Leukemia and Their Therapeutic Implications

Innate immunity constitutes the first line of host defense against various anomalies in humans, and it also guides the adaptive immune response. The function of innate immune components and adaptive immune components are interlinked in hematological malignancies including chronic lymphocytic leukemia (CLL), and molecular interactions between innate and adaptive immune components are crucial for the development, progression and the therapeutic outcome of CLL. In this leukemia, genetic mutations in B cells and B cell receptors (BCR) are key driving factors along with evasion of cytotoxic T lymphocytes and promotion of regulatory T cells. Similarly, the release of various cytokines from CLL cells triggers the protumor phenotype in macrophages that further edges the CLL cells. Moreover, under the influence of various cytokines, dendritic cells are unable to mature and trigger T cell mediated antitumor response. The phenotypes of these cells are ultimately controlled by respective signaling pathways, the most notables are BCR, Wnt, Notch, and NF-κB, and their activation affects the cytokine profile that controls the pathogenesis of CLL, and challenge its treatment. There are several novel substances for CLL under clinical development, including kinase inhibitors, antibodies, and immune-modulators that offer new hopes. DC-based vaccines and CAR T cell therapy are promising tools; however, further studies are required to precisely dissect the molecular interactions among various molecular entities. In this review, we systematically discuss the involvement, common targets and therapeutic interventions of various cells for the better understanding and therapy of CLL.

Recent clinical trends in Toll-like receptor targeting therapeutics

Toll‐like receptors (TLRs) are germline‐encoded receptors that are central to innate and adaptive immune responses. Owing to their vital role in inflammation, TLRs are rational targets in clinics; thus, many ligands and biologics have been reported to overcome the progression of various inflammatory and malignant conditions and support the immune system. For each TLR, at least one, and often many, drug formulations are being evaluated. Ligands reported as stand‐alone drugs may also be reported based on their use in combinatorial therapeutics as adjuvants. Despite their profound efficacy in TLR‐modulation in preclinical studies, multiple drugs have been terminated at different stages of clinical trials. Here, TLR modulating drugs that have been evaluated in clinical trials are discussed, along with their mode of action, suggestive failure reasons, and ways to improve the clinical outcomes. This review presents recent advances in TLR‐targeting drugs and provides directions for more successful immune system manipulation.

Basic understanding and therapeutic approaches to target toll-like receptors in cancerous microenvironment and metastasis

Toll-like receptors (TLRs) are transmembrane components that sense danger signals, like damage- and pathogen-associated molecular pattern molecules, as receptors, and maintain homeostasis in tissues. They are mainly involved in immune system activation through a variety of mediators, which either carry out (1) elimination of pathogenic threats and redressing homeostatic imbalances or (2) contribution to the initiation and worsening of pathological conditions, including cancers. Under physiological conditions, TLRs coordinate the innate and adaptive immunity, and inhibit autoimmune disorders. In pathological conditions, such as cancer, they can present both tumor and receptor-specific roles. Although the roles of individual TLRs in various cancers have been described, the effects of targeting TLRs to treat cancer and prevent metastasis are still controversial. A growing body of literature has suggested contribution of both activators and inhibitors of TLR signaling pathway for cancer treatment, dependent on several context-specific factors. In short, TLRs can play dual roles with contradictory outcomes in neoplastic conditions. This hampers the development of TLR-based therapeutic interventions. A better understanding of the interwoven TLR pathways in cancerous microenvironment is necessary to design TLR-based therapies. In this review, we consider the molecular mechanisms of TLRs signaling and their involvement in tumor progression. Therapeutic modalities targeting TLRs for cancer treatment are discussed as well.

Evaluation of Sox2 binding affinities for distinct DNA patterns using steered molecular dynamics simulation

Transcription factors (TFs) are gene expression regulators that bind to DNA in a sequence‐specific manner and determine the functional characteristics of the gene. It is worthwhile to study the unique characteristics of such specific TF‐binding pattern in DNA. Sox2 recognizes a 6‐ to 7‐base pair consensus DNA sequence; the central four bases of the binding site are highly conserved, whereas the two to three flanking bases are variable. Here, we attempted to analyze the binding affinity and specificity of the Sox2 protein for distinct DNA sequence patterns via steered molecular dynamics, in which a pulling force is employed to dissociate Sox2 from Sox2–DNA during simulation to study the behavior of a complex under nonequilibrium conditions. The simulation results revealed that the first two stacking bases of the binding pattern have an exclusive impact on the binding affinity, with the corresponding mutant complexes showing greater binding and longer dissociation time than the experimental complexes do. In contrast, mutation of the conserved bases tends to reduce the affinity, and mutation of the complete conserved region disrupts the binding. It might pave the way to identify the most likely binding pattern recognized by Sox2 based on the affinity of each configuration. The α2‐helix of Sox2 was found to be the key player in the Sox2–DNA association. The characterization of Sox2's binding patterns for the target genes in the genome helps in understanding of its regulatory functions.

Proteins Recognizing DNA: Structural Uniqueness and Versatility of DNA-Binding Domains in Stem Cell Transcription Factors

Proteins in the form of transcription factors (TFs) bind to specific DNA sites that regulate cell growth, differentiation, and cell development. The interactions between proteins and DNA are important toward maintaining and expressing genetic information. Without knowing TFs structures and DNA-binding properties, it is difficult to completely understand the mechanisms by which genetic information is transferred between DNA and proteins. The increasing availability of structural data on protein-DNA complexes and recognition mechanisms provides deeper insights into the nature of protein-DNA interactions and therefore, allows their manipulation. TFs utilize different mechanisms to recognize their cognate DNA (direct and indirect readouts). In this review, we focus on these recognition mechanisms as well as on the analysis of the DNA-binding domains of stem cell TFs, discussing the relative role of various amino acids toward facilitating such interactions. Unveiling such mechanisms will improve our understanding of the molecular pathways through which TFs are involved in repressing and activating gene expression.

Structure-Activity Relationship in TLR4 Mutations: Atomistic Molecular Dynamics Simulations and Residue Interaction Network Analysis

Toll-like receptor 4 (TLR4), a vital innate immune receptor present on cell surfaces, initiates a signaling cascade during danger and bacterial intrusion. TLR4 needs to form a stable hexamer complex, which is necessary to dimerize the cytoplasmic domain. However, D299G and T399I polymorphism may abrogate the stability of the complex, leading to compromised TLR4 signaling. Crystallography provides valuable insights into the structural aspects of the TLR4 ectodomain; however, the dynamic behavior of polymorphic TLR4 is still unclear. Here, we employed molecular dynamics simulations (MDS), as well as principal component and residue network analyses, to decipher the structural aspects and signaling propagation associated with mutations in TLR4. The mutated complexes were less cohesive, displayed local and global variation in the secondary structure, and anomalous decay in rotational correlation function. Principal component analysis indicated that the mutated complexes also exhibited distinct low-frequency motions, which may be correlated to the differential behaviors of these TLR4 variants. Moreover, residue interaction networks (RIN) revealed that the mutated TLR4/myeloid differentiation factor (MD) 2 complex may perpetuate abnormal signaling pathways. Cumulatively, the MDS and RIN analyses elucidated the mutant-specific conformational alterations, which may help in deciphering the mechanism of loss-of-function mutations.

Etoposide induced cytotoxicity mediated by ROS and ERK in human kidney proximal tubule cells

Etoposide (ETO) is a commonly used chemotherapeutic drug that inhibits topoisomerase II activity, thereby leading to genotoxicity and cytotoxicity. However, ETO has limited application due to its side effects on normal organs, especially the kidney. Here, we report the mechanism of ETO-induced cytotoxicity progression in human kidney proximal tubule (HK-2) cells. Our results show that ETO perpetuates DNA damage, activates mitogen-activated protein kinase (MAPK), and triggers morphological changes, such as cell and nuclear swelling. When NAC, a well-known reactive oxygen species (ROS) scavenger, is co-treated with ETO, it inhibits an ETO-induced increase in mitochondrial mass, mitochondrial DNA (ND1 and ND4) copy number, intracellular ATP level, and mitochondrial biogenesis activators (TFAM, PGC-1α and PGC-1β). Moreover, co-treatment with ETO and NAC inhibits ETO-induced necrosis and cell swelling, but not apoptosis. Studies using MAPK inhibitors reveal that inhibition of extracellular signal regulated kinase (ERK) protects ETO-induced cytotoxicity by inhibiting DNA damage and caspase 3/7 activity. Eventually, ERK inhibitor treated cells are protected from ETO-induced nuclear envelope (NE) rupture and DNA leakage through inhibition of caspase activity. Taken together, these data suggest that ETO mediates cytotoxicity in HK-2 cells through ROS and ERK pathways, which highlight the preventive avenues in ETO-induced cytotoxicity in kidney.

Toll-like receptors targeting technology for the treatment of lymphoma

INTRODUCTION

The crucial role of Toll-like Receptors (TLRs) in innate and adaptive immune systems is well discussed in the literature. In cancer, TLRs act as a double-edged sword that can promote or suppress tumor growth. Areas covered: In this article, the authors uncover the potential role of TLRs in lymphomas, which are cancers related to the lymphatic system and blood cells. TLRs are de facto inflammation-inducing receptors that can either worsen disease or ameliorate lymphoma treatment. From this perspective, the usage of TLRs to modulate the immune system toward lymphoma regression is desirable. Various strategies have been used so far, and novel ways are being sought out to cure lymphoma. Expert opinion: TLR ligands have successfully been used to improve patient health; however, these receptors must be finely tuned to further optimize therapy. For a better outcome, novel specific ligands, improved pharmacodynamics, and unique targets should be discerned. Ligands with conjugated molecules, nanoparticles, and targeted drug delivery can highly optimize the therapy for lymphoma with various etiologies.

Prolonged Mechanical Circumferential Stretch Induces Metabolic Changes in Rat Inferior Vena Cava

OBJECTIVE/BACKGROUND

Circumferential stretch on the vein wall has been suggested as a potential etiological factor in the development of varicose veins. However, the influence of vein wall stretch on vein metabolism has not yet been explored. The aim of this study was to investigate the effect of short and prolonged mechanical stretch on vein wall metabolism.

METHODS

Circular segments of inferior vena cava from male Sprague-Dawley rats were exposed to normal 0.5-g (nonstretched) or high 2-g (stretched) tension for short (4 h) or prolonged (18 h) duration (five vein segments per group). Contraction response to phenylephrine (10^-5 M) and KCl (96 mM) was elicited to observe the effect of circumferential stretch on vein function. The polar and organic metabolites in vein tissue were extracted using a bilayer extraction method. Aqueous and organic extracts were analyzed using nuclear magnetic resonance spectroscopy and ultra performance liquid chromatography coupled to mass spectrometry, respectively. Data acquired from both analytical platforms were analyzed using mathematical modeling.

RESULTS

Increased concentrations of valine (p = .02) and choline (p = .03) metabolites and triglyceride moieties (p = .03) were observed in veins stretched for 18 h compared with the nonstretched/18 h group.

DISCUSSION

Increased concentrations of branched chain amino acid valine and cell membrane constituent choline indicate increased muscle breakdown and increased metabolism of membrane phospholipids under stretch in an ex-vivo model. Increased intensities of triglyceride moieties in stretched vein segments for 18 h suggest that high pressure may induce an inflammatory response.

CONCLUSION

This study has shown that prolonged mechanical circumferential stretch (18 h) alters the metabolic profile of rat inferior vena cava.

Structural Mechanism behind Distinct Efficiency of Oct4/Sox2 Proteins in Differentially Spaced DNA Complexes

The octamer-binding transcription factor 4 (Oct4) and sex-determining region Y (SRY)-box 2 (Sox2) proteins induce various transcriptional regulators to maintain cellular pluripotency. Most Oct4/Sox2 complexes have either 0 base pairs (Oct4/Sox2^0bp) or 3 base pairs (Oct4/Sox2^3bp) separation between their DNA-binding sites. Results from previous biochemical studies have shown that the complexes separated by 0 base pairs are associated with a higher pluripotency rate than those separated by 3 base pairs. Here, we performed molecular dynamics (MD) simulations and calculations to determine the binding free energy and per-residue free energy for the Oct4/Sox2^0bp and Oct4/Sox2^3bp complexes to identify structural differences that contribute to differences in induction rate. Our MD simulation results showed substantial differences in Oct4/Sox2 domain movements, as well as secondary-structure changes in the Oct4 linker region, suggesting a potential reason underlying the distinct efficiencies of these complexes during reprogramming. Moreover, we identified key residues and hydrogen bonds that potentially facilitate protein-protein and protein-DNA interactions, in agreement with previous experimental findings. Consequently, our results confess that differential spacing of the Oct4/Sox2 DNA binding sites can determine the magnitude of transcription of the targeted genes during reprogramming.

Structural and conformational insights into SOX2/OCT4-bound enhancer DNA: a computational perspective

The roles of SOX2 and OCT4 are critical in stem cell maintenance either in the context of iPSCs generation or cancer stem cell growth; therefore, it is imperative to study their cooperative binding and SOX2/OCT4-induced DNA conformational switching.

The triumph of chemically enhanced cellular reprogramming: a patent review

INTRODUCTION

The revolutionary discovery of induced pluripotent stem cells (iPSCs) by Shinya Yamanaka has exposed science to new horizons. However, genetic modifications render reprogrammed cells unstable; for that reason, non-genetic modification approaches are actively under investigation. Among these, the use of small molecules is safe, and these molecules minimally affect the genome. Although iPSCs are ready for clinical trials there are many caveats hindering successful therapy, and small molecules are the best alternative to overcome those caveats.

AREAS COVERED

Small molecules are playing an active role in generating and improving the quality of iPSCs. In this review, we will highlight the imperative role of small molecules in accelerating the successful translation of basic research into clinical use. Particularly, those ligands that replace the need for reprogramming factors will be discussed.

EXPERT OPINION

Stem cell research is promising for harvesting medical benefits in near future. The invention of new techniques, mechanisms elucidation, and identification of novel compounds for stem cell creation has certainly established a solid foundation for regenerative medicine. This is the beginning of a new era for the cure of most disabling diseases, and small molecules will have a definite role in successful therapeutic use of iPSCs.

In silico mechanistic analysis of IRF3 inactivation and high-risk HPV E6 species-dependent drug response

The high-risk human papillomavirus E6 (hrHPV E6) protein has been widely studied due to its implication in cervical cancer. In response to viral threat, activated kinases phosphorylate the IRF3 autoinhibitory domain, inducing type1 interferon production. HPV circumvents the antiviral response through the possible E6 interaction with IRF3 and abrogates p53's apoptotic activity by recruiting E6-associated protein. However, the molecular mechanism of IRF3 inactivation by hrHPV E6 has not yet been delineated. Therefore, we explored this mechanism through in silico examination of protein-protein and protein-ligand docking, binding energy differences, and computational alanine mutagenesis. Our results suggested that the LxxLL motifs of IRF3 binds within the hydrophobic pocket of E6, precluding Ser-patch phosphorylation, necessary for IRF3 activation and interferon induction. This model was further supported by molecular dynamics simulation. Furthermore, protein-ligand docking and drug resistance modeling revealed that the polar patches in the pocket of E6, which are crucial for complex stability and ligand binding, are inconsistent among hrHPV species. Such variabilities pose a risk of treatment failure owing to point mutations that might render drugs ineffective, and allude to multi-drug therapy. Overall, this study reveals a novel perspective of innate immune suppression in HPV infections and suggests a plausible therapeutic intervention.

Mechanism of Cisplatin-Induced Cytotoxicity Is Correlated to Impaired Metabolism Due to Mitochondrial ROS Generation

The chemotherapeutic use of cisplatin is limited by its severe side effects. In this study, by conducting different omics data analyses, we demonstrated that cisplatin induces cell death in a proximal tubular cell line by suppressing glycolysis- and tricarboxylic acid (TCA)/mitochondria-related genes. Furthermore, analysis of the urine from cisplatin-treated rats revealed the lower expression levels of enzymes involved in glycolysis, TCA cycle, and genes related to mitochondrial stability and confirmed the cisplatin-related metabolic abnormalities. Additionally, an increase in the level of p53, which directly inhibits glycolysis, has been observed. Inhibition of p53 restored glycolysis and significantly reduced the rate of cell death at 24 h and 48 h due to p53 inhibition. The foremost reason of cisplatin-related cytotoxicity has been correlated to the generation of mitochondrial reactive oxygen species (ROS) that influence multiple pathways. Abnormalities in these pathways resulted in the collapse of mitochondrial energy production, which in turn sensitized the cells to death. The quenching of ROS led to the amelioration of the affected pathways. Considering these observations, it can be concluded that there is a significant correlation between cisplatin and metabolic dysfunctions involving mROS as the major player.

Fatal human eosinophilic meningo-encephalitis caused by CNS co-infection with Halicephalobus gingivalis and West Nile virus

The saprophytic nematode Halicephalobus is a rare cause of fatal human meningo-encephalitis, and West Nile virus is neurotropic flavivirus implicated in a variety of clinical neurologic syndromes. Here we report a case of rapidly progressive CNS encephalopathy and death. Serologic, immuno-histochemical, histopathologic and nucleic acid studies demonstrate the presence of active Halicephalobus and West Nile virus in the CNS tissue. This is the first reported case of co-infection with these neurotropic pathogens.

Insights into the species-specific TLR4 signaling mechanism in response to Rhodobacter sphaeroides lipid A detection

TLR4 in complex with MD2 senses the presence of lipid A (LA) and initiates a signaling cascade that curb the infection. This complex is evolutionarily conserved and can initiate the immune system in response to a variety of LAs. In this study, molecular dynamics simulation (25 ns) was performed to elucidate the differential behavior of TLR4/MD2 complex in response to Rhodobacter sphaeroides lipid A (RsLA). Penta-acyl chain-containing RsLA is at the verge of agonist (6 acyl-chains) and antagonist (4 acyl-chains) structure, and activates the TLR4 pathway in horses and hamsters, while inhibiting in humans and murine. In the time-evolved coordinates, the promising factors that dictated the differential response included the local and global mobility pattern of complexes, solvent-accessible surface area of ligand, and surface charge distributions of TLR4 and MD2. We showed that the GlcN1-GlcN2 backbone acquires agonist (3FXI)-like configurations in horses and hamsters, while acquiring antagonist (2E59)-like configurations in humans and murine systems. Moreover, analysis of F126 behavior in the MD2 F126 loop (amino acids 123-129) and loop EF (81-89) suggested that certain sequence variations also contribute to species-specific response. This study underlines the TLR4 signaling mechanism and provides new therapeutic opportunities.

Multiple roles of toll-like receptor 4 in colorectal cancer

Toll-like receptor (TLR) signaling has been implicated in the inflammatory responses in intestinal epithelial cells (IECs). Such inflammatory signals mediate complex interactions between commensal bacteria and TLRs and are required for IEC proliferation, immune response, repair, and homeostasis. The upregulation of certain TLRs in colorectal cancer (CRC) tissues suggests that TLRs may play an essential role in the prognosis of chronic and inflammatory diseases that ultimately culminate in CRC. Here, we provide a comprehensive review of the literature on the involvement of the TLR pathway in the initiation, progression, and metastasis of CRC, as well as inherited genetic variation and epigenetic regulation. The differential expression of TLRs in epithelial cells has also been discussed. In particular, we emphasize the physiological role of TLR4 in CRC development and pathogenesis, and propose novel and promising approaches for CRC therapeutics with the aid of TLR ligands.

Gram-negative marine bacteria: structural features of lipopolysaccharides and their relevance for economically important diseases

Gram-negative marine bacteria can thrive in harsh oceanic conditions, partly because of the structural diversity of the cell wall and its components, particularly lipopolysaccharide (LPS). LPS is composed of three main parts, an O-antigen, lipid A, and a core region, all of which display immense structural variations among different bacterial species. These components not only provide cell integrity but also elicit an immune response in the host, which ranges from other marine organisms to humans. Toll-like receptor 4 and its homologs are the dedicated receptors that detect LPS and trigger the immune system to respond, often causing a wide variety of inflammatory diseases and even death. This review describes the structural organization of selected LPSes and their association with economically important diseases in marine organisms. In addition, the potential therapeutic use of LPS as an immune adjuvant in different diseases is highlighted.

Vasoconstrictor and vasodilator responses to tryptamine of rat-isolated perfused mesentery: comparison with tyramine and β-phenylethylamine

BACKGROUND AND PURPOSE

Tryptamine increases blood pressure by vasoconstriction, but little is known about its actions on the mesentery, in particular the resistance arteries. Tryptamine interacts with trace amine-associated receptors (TAARs) and because of its structural similarity to 5-HT, it may also interact with 5-HT receptors. Our hypothesis is therefore that the rat mesenteric arterial bed will exhibit vasopressor and vasodepressor responses to tryptamine via both 5-HT and TAARs.

EXPERIMENTAL APPROACH

Tryptamine-evoked responses were assayed from pressure changes of the rat-isolated mesenteric vasculature perfused at constant flow rate in the absence and presence of adrenoceptor and 5-HT receptor antagonists.

KEY RESULTS

Tryptamine caused dose-dependent vasoconstriction of the mesenteric arterial bed as increases in perfusion pressure. These were unaffected by the α₁-adrenoceptor antagonist, prazosin, but were attenuated by the non-selective α-adrenoceptor antagonist, phentolamine. The 5-HT_2A receptor antagonists, ketanserin and ritanserin, abolished the tryptamine-induced pressure increases to reveal vasodilator responses in mesenteric beds preconstricted with phenylephrine. These tryptamine-induced vasodilator responses were unaffected by the 5-HT₇ receptor antagonist, SB269970, but were eliminated by the NOS inhibitor, N_ω-nitro-L-arginine methyl ester (L-NAME). Tyramine and β-phenylethylamine also caused vasodilatation in pre-constricted vasculature, which was also abolished by L-NAME.

CONCLUSIONS AND IMPLICATIONS

Tryptamine causes vasoconstriction of the mesenteric vasculature via 5-HT_2A receptors, which when inhibited exposed vasorelaxant effects in pre-constricted tissues. The vasodilatation was independent of 5-HT_2A and 5-HT₇ receptors but like that for tyramine and β-phenylethylamine was due to NO release. Potency orders suggest TAAR involvement in the vasodilatation by these trace amines.

Complications of Radiofrequency Ablation of Varicose Veins

Radiofrequency ablation (RFA) has become a valued weapon in the phlebologist's armoury. It offers ease of use and reproducibility with good outcomes. However, as with all interventions, complications arise. In this review we examine the complications inherent with RFA and their relative risk, with their avoidance measures if available. Overall, we find that RFA offers a very safe procedure with rare severe complications.

Gallstone ileus: a difficult emergency diagnosis!

Gallstone ileus (GSI) is a rare cause of mechanical small bowel obstruction. It occurs when a fistula between the gallbladder and the small bowel facilitates the migration of gallstone(s) into the small bowel. The commonest site of impaction is in the terminal ileum. We report the case of a 71-year-old female presenting with GSI diagnosed on CT scan. She was surgically explored and gallstones extracted by a simple enterotomy leading to full recovery of the patient.

Glucose oxidase immobilization on a novel cellulose acetate–polymethylmethacrylate membrane

Glucose oxidase (GOD) was immobilized on cellulose acetate-polymethylmethacrylate (CA-PMMA) membrane. The immobilized GOD showed better performance as compared to the free enzyme in terms of thermal stability retaining 46% of the original activity at 70 degrees C where the original activity corresponded to that obtained at 20 degrees C. FT-IR and SEM were employed to study the membrane morphology and structure after treatment at 70 degrees C. The pH profile of the immobilized and the free enzyme was found to be similar. A 2.4-fold increase in Km value was observed after immobilization whereas Vmax value was lower for the immobilized GOD. Immobilized glucose oxidase showed improved operational stability by maintaining 33% of the initial activity after 35 cycles of repeated use and was found to retain 94% of activity after 1 month storage period. Improved resistance against urea denaturation was achieved and the immobilized glucose oxidase retained 50% of the activity without urea in the presence of 5M urea whereas free enzyme retained only 8% activity.

Electrochemical approach of anticancer drugs--DNA interaction

The interaction of drugs with DNA is among the most important aspects of biological studies in drug discovery and pharmaceutical development processes. In recent years there has been a growing interest in the electrochemical investigation of interaction between anticancer drugs and DNA. Observing the pre and post electrochemical signals of DNA or drug interaction provides good evidence for the interaction mechanism to be elucidated. Also this interaction could be used for the quantification of these drugs and for the determination of new drugs targeting DNA. Electrochemical approach can provide new insight into rational drug design and would lead to further understanding of the interaction mechanism between anticancer drugs and DNA.

Intestinal Protozoa in Wild Boars (Sus scrofa) in Western Iran

A total of 12 gastrointestinal tracts of wild boars (Sus scrofa) from western Iran (Luristan) were examined for protozoan infection between September 2000 and November 2001. Of 12 boars examined, 67% harbored one or more species of the following protozoa: Balantidium coli (25%), Tritrichomonas suis (25%), Blastocystis sp. (25%), Entamoeba polecki (17%), Entamoeba suis (8%), Iodamoeba butschlii (17%), and Chilomastix mesnili (8%). Four of these protozoan species also are reported in humans, and persons living in rural areas where wild boars are abundant should take precaution to avoid infection.

Coccidiosis in the European badger, Meles meles in Wytham Woods: infection and consequences for growth and survival

In total 1502 faecal samples were collected from a population of European badgers (Meles meles) between 1992 and 1995 at Wytham Woods, Oxfordshire, UK. Two coccidia species, Eimeria melis and Isospora melis, were identified. Cubs showed a marked seasonal pattern of infection with E. melis, with infection occurring at significantly higher intensity and prevalence than in adults. There was preliminary evidence to suggest that infantile coccidiosis in badgers may be associated with impaired growth and increased mortality.

Developmental changes in reactivity of small femoral arteries in the fetal and postnatal baboon

OBJECTIVE

We evaluated in vitro responsiveness of small arteries (internal diameter, 300 microm) from the femoral vascular bed of normal fetal (0.75-1.0 gestation) and neonatal (43-46 days) baboons to investigate whether the transition from fetal to neonatal life was associated with functional alterations in vasoconstrictor and vasodilator responses.

STUDY DESIGN

The maximum response and sensitivity to potassium and to the constrictor agonists norepinephrine and U46619 (a thromboxane mimetic) were studied by in vitro myography. Vasodilator responses to the endothelium-dependent dilators acetylcholine and bradykinin were also investigated.

RESULTS

The maximum response to norepinephrine and U46619 and to potassium increased with gestational age, whereas the sensitivity to these vasoconstrictors was similar in all groups studied. In contrast, acetylcholine- and bradykinin-induced relaxation (median effective concentration and maximum response) did not change with age.

CONCLUSION

Receptor-mediated responses to a catecholamine, a prostanoid, and 2 endotheliumdependent vasodilators are similar in the fetal and neonatal baboon. The increase in maximal constriction with development, which is probably associated with growth or maturation of vascular smooth muscle, is likely to be a functionally important aspect in the development of cardiovascular function.

Non-linear changes of electrocortical activity after antenatal betamethasone treatment in fetal sheep

We determined the effects of betamethasone on the fetal sheep electrocorticogram (ECoG) using linear (power spectral) and non-linear analysis. For non-linear analysis we used an algorithm based on the Wolf algorithm for the estimation of the leading Lyapunov exponent which calculates a prediction error based on the course of the time series in the phase space. A high prediction error stands for low predictibility or low regularity and vice versa. After 48 h of baseline recordings, vehicle (n = 6) or betamethasone (n = 7) at 10 microg h(-1) was infused over 48 h to the sheep fetus at 128 days gestational age (0.87 of gestation). ECoG spectral analysis revealed no difference in power spectrum between vehicle- and betamethasone-treated fetuses. The prediction error of the ECoG during REM sleep was higher than during non-REM or quiet sleep in both groups (P < 0.0001) revealing lower causality of brain activity during REM sleep. During REM sleep, prediction error significantly decreased 18-24 h after onset of betamethasone treatment (P < 0.05) and returned to baseline values within the following 24 h of continued betamethasone treatment. No ECoG changes were found during quiet sleep. Non-linear ECoG changes during metabolically active REM sleep accompanied the previously described decrease in cerebral blood flow. These results suggest that betamethasone in doses used in perinatal medicine acutely alters complex neuronal activity.

Effects of betamethasone administration to the fetal sheep in late gestation on fetal cerebral blood flow

Glucocorticoid administration to women at risk of preterm delivery to accelerate fetal lung maturation has become standard practice. Antenatal glucocorticoids decrease the incidence of intraventricular haemorrhage as well as accelerating fetal lung maturation. Little is known regarding side effects on fetal cerebral function. Cortisol and synthetic glucocorticoids such as betamethasone increase fetal blood pressure and femoral vascular resistance in sheep. We determined the effects of antenatal glucocorticoid administration on cerebral blood flow (CBF) in fetal sheep. Vehicle (n = 8) or betamethasone (n = 8) was infused over 48 h via the jugular vein of chronically instrumented fetal sheep at 128 days gestation (term 146 days). The betamethasone infusion rate was that previously shown to produce fetal plasma betamethasone concentrations similar to human umbilical vein concentrations during antenatal glucocorticoid therapy. Regional CBF was measured in 10 brain regions, using coloured microspheres, before and 24 and 48 h after onset of treatment, and during hypercapnic challenges performed before and 48 h after onset of betamethasone exposure. Betamethasone exposure decreased CBF in all brain regions measured except the hippocampus after 24 h of infusion (P < 0.05). The CBF decrease was most pronounced in the thalamus and hindbrain (45-50% decrease) and least pronounced in the cortical regions (35-40% decrease). It was mediated by an increase in cerebral vascular resistance (CVR, P < 0.05) and led to a decrease in oxygen delivery to subcortical and hindbrain structures of 30-40%, to 8.6 +/- 1.1 ml x (100 g)(-1) x min(-1), and 40-45 %, to 11.0 +/- 1.6 ml x 100 g(-1) x min(-1), respectively (P < 0.05). After 48 h of betamethasone treatment, the reduction in CBF was diminished to about 25-30 %, but was still significant in comparison to vehicle-treated fetuses in all brain regions except three of the five measured cortical regions (P < 0.05). CVR and oxygen delivery were unchanged in comparison to values at 24 h of treatment. The CBF increase in response to hypercapnia was diminished (P < 0.05). These observations demonstrate for the first time that glucocorticoids exert major vasoconstrictor effects on fetal CBF. This mechanism may protect the fetus against intraventricular haemorrhage both at rest and when the fetus is challenged. Betamethasone exposure decreased the hypercapnia-induced increase in CBF (P < 0.05) due to decreased cerebral vasodilatation (P < 0.05).

Coccidiosis in the European badger (Meles meles) from England, an epidemiological study

In total 445 faecal samples were collected from 259 European badgers (Meles meles) in Wytham Woods, Oxfordshire, UK (462080). Microscopical examination revealed infection with 2 species of coccidia Eimeria melis and Isospora melis. From the initial examination of each animal, point prevalence rates of 0.44 and 0.35 were calculated for Eimeria and Isospora respectively. The intensity of infection was significantly greater for Eimeria than Isopora and the distribution of intensities was highly skewed for both species, with a few individuals shedding the majority of oocysts. Incidence and recovery rates for both coccidia species were calculated from longitudinal data collected at 3-monthly intervals from a subset of the adult badger population, and the predicted prevalence rates based on these were similar to the point prevalence rates. This suggests little, if any, parasite-induced mortality in the adult population. In contrast, there was a marked and significant reduction in the point prevalence and intensity of infection with Eimeria from cub to adult badger suggesting a degree of acquired immunity to Eimeria melis on initial exposure and/or that there is significant Eimeria-associated mortality in the cub population. No such relationship was found for Isospora infection. In those adult badgers with co-infections there was a direct relationship between the intensity of Eimeria and Isospora. The taxonomic status of these parasites suggests a heteroxenous life-cycle for I. melis, and direct transmission of E. melis. However, the greater than expected prevalence of co-infection is consistent with a common source of infection, such as communal latrines.

A comparative study of vascular responsiveness of myometrial and omental small resistance arteries in late-gestation sheep

OBJECTIVE

We determined whether local regulation by vasoactive agents differs in the myometrial and omental vascular beds in the pregnant sheep. Specifically, we hypothesized that there would be blunting of in vitro responses to constrictor agonists, enhancement of sensitivity to dilator agonists, or both in myometrial compared with omental resistance arteries.

STUDY DESIGN

We compared in vitro responsiveness of small resistance intramyometrial and omental arteries from near-term pregnant ewes to the vasoconstrictor agents norepinephrine, U46619 (a thromboxane sympathomimetic), and potassium and the vasodilator agents acetylcholine and bradykinin.

RESULTS

The vascular sensitivity and the maximum response of intramyometrial small arteries to U46619 was attenuated compared with that of omental arteries. There were no significant differences between the intramyometrial and omental arteries in response to norepinephrine, potassium, acetylcholine, or bradykinin.

CONCLUSIONS

These results support regional heterogeneity of regulation of function in different maternal vascular beds during pregnancy. The relative insensitivity of the myometrial arteries to the thromboxane mimetic indicates the existence of decreased constrictor function that may facilitate preservation of uterine blood flow in vivo.

Betamethasone-mediated vascular dysfunction and changes in hematological profile in the ovine fetus

Glucocorticoid administration to fetal sheep induces a sustained systemic blood pressure rise and an associated increase in femoral vascular resistance. We utilized a small vessel myograph to compare isometric vascular responses of small femoral arterial branches from fetal sheep infused intravenously with either betamethasone or vehicle in vivo from 128 days gestation. Changes in hematological parameters were also determined. Betamethasone was infused for 48 h to produce fetal plasma betamethasone concentrations similar to those observed in human fetuses after maternal treatment with betamethasone to accelerate fetal lung maturation. When compared with vessels removed from vehicle-infused fetuses, vessels obtained from betamethasone-treated fetuses exhibited 1) enhanced sensitivity to depolarizing potassium solutions; 2) no differences in response to the thromboxane mimetic U-46619 or norepinephrine; and 3) differential responses to vasodilators, enhanced sensitivity to ACh, but decreased response to bradykinin and forskolin. In addition, erythrocyte and leukocyte counts were increased in betamethasone-infused fetuses. These observations indicate that multiple mechanisms operate to increase fetal vascular resistance during antenatal betamethasone exposure.

Enhanced acetylcholine induced relaxation in small mesenteric arteries from pregnant rats: an important role for endothelium-derived hyperpolarizing factor (EDHF)

1. Small mesenteric arteries from pregnant rats demonstrated greater sensitivity (pEC50 : P<0.001) and maximum relaxation (P<0.01) to acetylcholine (ACh) than those of control non-pregnant animals. 2. Maximum relaxation, but not sensitivity, to ACh remained greater (P<0.01) in pregnant animals when evaluated in 25 mM KCl, which prevents relaxation dependent upon hyperpolarization. ACh induced relaxation in the presence of 25 mM KCl was completely inhibited in pregnant and non-pregnant groups by N(omega)-nitro L-arginine methyl ester (L-NAME, 100 microM), indomethacin (INDO, 10 microM) and oxadiazole quinoxalin (ODQ, 1 microM), suggesting pregnancy associated enhancement of dilator prostanoid and/or nitric oxide (NO) synthesis. 3. ACh induced relaxation in 5 mM KCI was only partially inhibited by a combination of N(omega)-nitro L-arginine methyl ester (L-NAME, 100 microM), indomethacin (INDO, 10 microM) and oxadiazole quinoxalin (ODQ, 1 microM). The residual relaxation, which was greater in arteries from pregnant rats (maximum relaxation: P<0.01), was prevented by 25 mM KCl, indicating pregnancy associated enhanced synthesis/ reduced degradation of a hyperpolarizing factor. Residual relaxation to ACh in 5 mM KCl was inhibited by the cytochrome P450 inhibitor, proadifen (1 microM) in the pregnant group (P<0.001). 4. Relaxation to spermine NONOate was similar in pregnant and non-pregnant groups and totally inhibited by ODQ (in the presence of L-NAME). 5. This study suggests that, in addition to enhanced endothelium dependent NO/dilator prostanoid synthesis, a hyperpolarizing factor may contribute to the vascular adaptation to pregnancy.

Fowlpox virus encodes nonessential homologs of cellular alpha-SNAP, PC-1, and an orphan human homolog of a secreted nematode protein

The genome of fowlpox virus (FWPV), type species of the Avipoxviridae, is considerably rearranged compared with that of vaccinia virus (the prototypic poxvirus and type species of the Orthopoxviridae) and is 30% larger. It is likely that the genome of FWPV contains genes in addition to those found in vaccinia virus, probably involved with its replication and survival in the chicken. A 7,470-bp segment of the FWPV genome has five open reading frames (ORFs), two of which encode ankyrin repeat proteins, many examples of which have been found in poxviruses. The remaining ORFs encode homologs of cellular genes not reported in any other virus. ORF-2 encodes a homolog of the yeast Sec17p and mammalian SNAP proteins, crucial to vesicular transport in the exocytic pathway. ORF-3 encodes a homolog of an orphan human protein, R31240_2, encoded on 19p13.2. ORF-3 is also homologous to three proteins (YLS2, YMV6, and C07B5.5) from the free-living nematode Caenorhabditis elegans and to a 43-kDa antigen from the parasitic nematode Trichinella spiralis. ORF-5 encodes a homolog of the mammalian plasma cell antigen PC-1, a type II glycoprotein with exophosphodiesterase activity. The ORFs are present in the virulent precursor, HP1, of the sequenced attenuated virus (FP9) and are conserved in other strains of FWPV. They were shown, by deletion mutagenesis, to be nonessential to virus replication in tissue culture. RNA encoding the viral homolog of PC-1 is expressed strongly early and late in infection, but RNAs encoding the homologs of SNAP and R31240_2 are expressed weakly and late.

Loss of cell surface microvilli on rat basophilic leukaemia cells precedes secretion and can be mimicked using the calmodulin antagonist trifluoperazine

OBJECTIVE

We studied changes in cell surface morphology following treatment with secretagogue or trifluoperazine in a mast cell model.

MATERIALS AND METHODS

Rat basophilic leukaemia (RBL) cells were treated with antigen and or the calmodulin antagonist, 0-50 microM trifluoperazine (TFP). The release of a secretory granule enzyme, beta-hexosaminidase, into the external medium was used as a measure of secretion. Quantitation of cell surface microvilli was determined by using a computer with input from a digitising tablet from scanning electron micrographs. Cytoskeletal proteins present in microvilli were analysed by confocal immunofluorescence.

RESULTS

When RBL cells are stimulated to secrete with an antigen, the cell surface is transformed from a microvillous morphology to a ruffled one. The cell surface rearrangement preceded beta-hexosaminidase secretion: the majority of microvilli disappeared rapidly after stimulation (t1/2 of 39 s) whereas secretion can only be measured after a lag of 47 s. The calmodulin antagonist, TFP did not inhibit antigen-induced secretion or loss of microvilli, however TFP alone caused a similar loss of microvilli but was unable to stimulate or potentiate secretion. The microvilli mostly disappeared within 30 s, and a half-maximal effect occurred at approximately 8 microM TFP. Using immunofluorescence, calmodulin was localized to punctate structures on the dorsal cell surface which presumably correspond to the microvilli, and which also stained for F-actin and myosin I.

CONCLUSIONS

Loss of cell surface microvilli on RBL cells precedes secretion and could reflect a cytoskeletal rearrangement which facilitates fusion of secretory granules with the membrane. It can be mimicked using trifluoperazine and we suggest it may involve calmodulin-binding components of the microvillus cytoskeleton such as myosin I.

The variation with gestational age of the rheological properties of the blood of the new-born

A study has been made of the variation of blood viscosity and related factors with the gestational age of neonates from 24 weeks to normal term. Viscosity increases significantly over this period by 36% at high shear rate (128.5 s-1) and 250% at low shear (0.277 s-1). The high shear rate changes can be explained largely by the effects of variations in haematocrit and plasma viscosity. At low shear rate the same factors are involved together with changes in the plasma protein composition, in particular the age-related increase in the concentration of the proteins known to induce rouleaux formation. The variation in the degree of sialination of fibrinogen with gestational age may also play a part.