Proteolysis-targeting chimeras with reduced off-targets

Proteolysis-targeting chimeras (PROTACs) are molecules that induce proximity between target proteins and E3 ligases triggering target protein degradation. Pomalidomide, a widely used E3 ligase recruiter in PROTACs, can independently degrade other proteins, including zinc-finger (ZF) proteins, with vital roles in health and disease. This off-target degradation hampers the therapeutic applicability of pomalidomide-based PROTACs, requiring development of PROTAC design rules that minimize off-target degradation. Here we developed a high-throughput platform that interrogates off-target degradation and found that reported pomalidomide-based PROTACs induce degradation of several ZF proteins. We generated a library of pomalidomide analogues to understand how functionalizing different positions of the phthalimide ring, hydrogen bonding, and steric and hydrophobic effects impact ZF protein degradation. Modifications of appropriate size on the C5 position reduced off-target ZF degradation, which we validated through target engagement and proteomics studies. By applying these design principles, we developed anaplastic lymphoma kinase oncoprotein-targeting PROTACs with enhanced potency and minimal off-target degradation.

Development and Applications of Chimera Platforms for Tyrosine Phosphorylation

Chimeric small molecules that induce post-translational modification (PTM) on a target protein by bringing it into proximity to a PTM-inducing enzyme are furnishing novel modalities to perturb protein function. Despite recent advances, such molecules are unavailable for a critical PTM, tyrosine phosphorylation. Furthermore, the contemporary design paradigm of chimeric molecules, formed by joining a noninhibitory binder of the PTM-inducing enzyme with the binder of the target protein, prohibits the recruitment of most PTM-inducing enzymes as their noninhibitory binders are unavailable. Here, we report two platforms to generate phosphorylation-inducing chimeric small molecules (PHICS) for tyrosine phosphorylation. We generate PHICS from both noninhibitory binders (scantily available, platform 1) and kinase inhibitors (abundantly available, platform 2) using cysteine-based group transfer chemistry. PHICS triggered phosphorylation on tyrosine residues in diverse sequence contexts and target proteins (e.g., membrane-associated, cytosolic) and displayed multiple bioactivities, including the initiation of a growth receptor signaling cascade and the death of drug-resistant cancer cells. These studies provide an approach to induce biologically relevant PTM and lay the foundation for pharmacologic PTM editing (i.e., induction or removal) of target proteins using abundantly available inhibitors of PTM-inducing or -erasing enzymes.

Proximity-inducing modalities: the past, present, and future

Living systems use proximity to regulate biochemical processes. Inspired by this phenomenon, bifunctional modalities that induce proximity have been developed to redirect cellular processes. An emerging example of this class is molecules that induce ubiquitin-dependent proteasomal degradation of a protein of interest, and their initial development sparked a flurry of discovery for other bifunctional modalities. Recent advances in this area include modalities that can change protein phosphorylation, glycosylation, and acetylation states, modulate gene expression, and recruit components of the immune system. In this review, we highlight bifunctional modalities that perform functions other than degradation and have great potential to revolutionize disease treatment, while also serving as important tools in basic research to explore new aspects of biology.

A general approach to identify cell-permeable and synthetic anti-CRISPR small molecules

The need to control the activity and fidelity of CRISPR-associated nucleases has resulted in a demand for inhibitory anti-CRISPR molecules. The small-molecule inhibitor discovery platforms available at present are not generalizable to multiple nuclease classes, only target the initial step in the catalytic activity and require high concentrations of nuclease, resulting in inhibitors with suboptimal attributes, including poor potency. Here we report a high-throughput discovery pipeline consisting of a fluorescence resonance energy transfer-based assay that is generalizable to contemporary and emerging nucleases, operates at low nuclease concentrations and targets all catalytic steps. We applied this pipeline to identify BRD7586, a cell-permeable small-molecule inhibitor of SpCas9 that is twofold more potent than other inhibitors identified to date. Furthermore, unlike the reported inhibitors, BRD7586 enhanced SpCas9 specificity and its activity was independent of the genomic loci, DNA-repair pathway or mode of nuclease delivery. Overall, these studies describe a general pipeline to identify inhibitors of contemporary and emerging CRISPR-associated nucleases.

Chemogenetic System Demonstrates That Cas9 Longevity Impacts Genome Editing Outcomes

Prolonged Cas9 activity can hinder genome engineering as it causes off-target effects, genotoxicity, heterogeneous genome-editing outcomes, immunogenicity, and mosaicism in embryonic editing-issues which could be addressed by controlling the longevity of Cas9. Though some temporal controls of Cas9 activity have been developed, only cumbersome systems exist for modifying the lifetime. Here, we have developed a chemogenetic system that brings Cas9 in proximity to a ubiquitin ligase, enabling rapid ubiquitination and degradation of Cas9 by the proteasome. Despite the large size of Cas9, we were able to demonstrate efficient degradation in cells from multiple species. Furthermore, by controlling the Cas9 lifetime, we were able to bias the DNA repair pathways and the genotypic outcome for both templated and nontemplated genome editing. Finally, we were able to dosably control the Cas9 activity and specificity to ameliorate the off-target effects. The ability of this system to change the Cas9 lifetime and, therefore, bias repair pathways and specificity in the desired direction allows precision control of the genome editing outcome.

Microinvasion: A Clinical Dilemma

Microinvasive oral squamous cell carcinoma (MIOSCC) is an early stage malignant tumour,showing invasion of the epithelial cells confined to the superficial lamina propria. This is matter of debate in respect to the clinical presentation, metastasis, therapeutic intervention and prognosis. A 32-year female reported to the department with chief complaint of wound and burning sensation in her left back region of lower gums. Clinical diagnosis of erosive oral lichen planus was made and topical steroid was started. The lesion clinically healed with the use of topical medicine. After stopping the medication the lesion recurred, following which, excisional biopsy was done. On histopathological evaluation diagnosis of microinvasive oral squamous cell carcinoma was made. Recurrence of similar symptom in the same site was seen 10 weeks later, which now showed features of moderate dysplasia. Clinical features of microinvasive oral squamous cell carcinoma resembles premalignant lesion, leading to difficulty in diagnosis, treatment and prognostic assessment. Thus, adequate representation of this entity is necessary.

Effect of graded levels of soapnut (Sapindus mukorossi) shell powder on reproductive performance in broiler breeders

Objective

This study investigated the effects of soapnut (Sapindus mukorossi) shell powder (SSP) on serum hormone level, egg quality, semen characteristics and reproductive performance of broiler breeders fed with a maize-soybean meal based diet.

Methods

Ninety six female and twenty four male CARIBRO-VISHAL broiler breeders, 38-week old, were individually caged and randomly allocated to four treatment groups (24 female breeders/treatment and 6 male breeders/treatment): an un-supplemented control (T1) and three groups with 0.0176% SSP (group T2), 0.026% SSP (group T3) and 0.0528% SSP (group T4), to have supplementary saponin at 0, 50, 75, and 150 ppm, respectively, for 42 days.

Results

The results indicated that serum (p<0.001) and seminal plasma (p<0.05) testosterone level, semen volume (p<0.001), mass motility (p<0.001), and live spermatozoa count (p<0.001) was increased in groups T3 and T4 compared to T2 and control groups. Compared with control group, total sperm count was increased (p<0.001) and dead spermatozoa count was decreased (p<0.001) in SSP supplemented groups. Supplementation of SSP did not affected the quality of egg lay. Compared with control group, fertility (p<0.01) and hatchability (total eggs set and fertile eggs set) (p<0.001) were significantly improved in SSP supplemented groups with the highest improvement in T3 treatment group. Embryonic death was decreased (p< 0.001) in SSP supplemented groups compared to control; lowest embryonic death was recorded in T3 treatment group.

Conclusion

Thus, it was concluded that dietary supplementation of 0.026% SSP (saponin equivalent 75 ppm) improved the reproductive performance of broiler breeders.

Factors Affecting the Success Rate of External Dacryocystorhinostomy at B. P. Koirala Institute of Health Sciences, Dharan, Nepal

IntroductionAny disturbance to the normal ouVlow of tears through the nasolacrimal passage causes overflow known as epiphora. The clinical symptoms of epiphora range from mild dribble to the continuous ouVlow of tears. Watering of eyes caused by the nasolacrimal drainage  obstruction  is  managed  by surgery. One of the many surgeries to treat this is external dacryocystorhinostomy.ObjectiveThe objective of this study was to evaluate the success rate of external dacryocystorhinostomy as well as factors affecting it.MethodologyThis is a retrospective cross-sectional study, conducted in the Department of Ophthalmology, B. P. Koirala Institute of Health Sciences (BPKIHS), Dharan with the approval of Institutional Review Committee, BPKIHS. The medical records of patients who underwent external Dacryocystorhinostomy surgery from April 2011 to April 2016 at BPKIHS were retrospectively reviewed. Statistical analysis was performed using SPSS for windows, version 11.5 (SPSS Inc., Chicago, IL). Binary logistic regression models were used to investigate the association of the surgical outcome with various predicting variables.ResultsThe success rate of the external dacryocystorhinostomy was 78.09%. Factors studied were: age, with a range of 2-81 years; duration of symptoms with a range of 1-84 months; and gender of the patients. The intra-operative factors studied were use of silastic tube, types of flap, and osteotomy size. Among these factors, the duration of symptoms and osteotomy size had significant association with the outcome of the surgery p<0.05.ConclusionOur study yielded high success rate in patients with shorter duration of watering of eyes and larger osteotomy size during surgery. Hence, a larger osteotomy size and early intervention is recommended for better surgical outcome. Birat Journal of Health Sciences Vol.2/No.1/Issue 2/ Jan - April 2017, Page: 196-200

Bulk synthesis of multi-walled carbon nanotubes by AC arc discharge method

This work proposes the production of multi-walled carbon nanotubes by AC arc discharging of spectroscopically pure graphite electrodes of different shapes, that is, movable cylindrical and stationary rectangular electrode by manual metal arc welding setup. Continuous arc was generated by maintaining the gap of about 3 mm between the electrodes which in turn formed the plasma zone. Vaporization of carbon cations followed by sudden quenching paved the way for formation of carbon nantotubes. Nanotubes produced were deposited on the stationary graphite electrode in the form of soot. Further extraction of the nanoparticles from the soot was performed by conducting series of purification processes which will be discussed in upcoming chapters. Morphology and purity of the extracted nanotubes were investigated by X-ray diffraction, scanning electron microscopy, field-emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. Following the characterization process, it was observed that the so-produced nanotubes were of different shapes, that is, carbon cone nanotubes, nanocapsules, nanoparticles and branching type and randomly oriented. The length of the nanotubes varied from 231 to 561 nm, whereas diameter was found to be in the range of 14–55 nm.

Acute renal failure in Nepal Medical College Teaching Hospital

Total 45 patients (male 27 and female 18) of acute renal failure (ARF) admitted in Nepal Medical College Teaching Hospital over a period of 12 months (1st of Baisakh 2064 BS to 31st of Chaitra 2064 BS) were enrolled in the study. Sixty four percent of study population were of age group 21-60 years. Acute Gastroenteritis 33, sepsis 5, hemorrhage 2, others 5 were the different causes of ARF. Serum creatinine of the study population before and after treatment was 4.35 +/- 2.72 and 1.38 +/- 0.72 mg/dl respectively. Similarly serum urea before and after treatment was 101.78 +/- 57.56 and 42.60 +/- 30.46 mg/dl respectively. Thirty three patients were managed by non dialytic modality of therapy and 12 patients needed hemodialysis. Blood urea of those patients who underwent nondialytic therapy was significantly less than of those who underwent hemodialysis (80.65 +/- 38.21 vs. 151.08 +/- 66.22; p = 0.004). Serum creatinine was also significantly lower in nondialytic therapy group (3.15 +/- 1.15 vs. 7.64 +/- 3.10; p = 0.000) ARF patients with very high urea, creatinine and disturbed electrolytes required dialysis. Average session of hemodialysis was 3.4. Thirty five patients were cured, 6 left against medical advice, 3 were discharged on request, and one patient of sepsis expired during the course of treatment. Acute gastroenteritis was the leading cause of ARF and outcome was excellent even without dialysis in most of the cases provided the treatment was started early and appropriately.

Profound hypothermic circulatory arrest in management of aortic aneurysms

A total of 15 patients having aneurysms of aorta were operated from June 1997 to December 1998 using deep hypothermic circulatory arrest as a modality of brain protection. There were 12 males and 3 females. The age ranged from 19 years to 74 years and the mean age was 44.9 years. Nine patients had aneurysms of ascending aorta (group I), one had aneurysm of ascending aorta and arch of aorta (group II), four had aneurysm of the distal aortic arch (group III) and one patient had thoracoabdominal aortic aneurysm (group IV). In group I, six patients underwent Bentall procedure, two underwent Wheat procedure and one patient had repair of pseudoaneurysm of ascending aorta. The only patient in group II had his ascending aorta and arch replaced, with reimplantation of left common carotid and innominate artery. In group III, three patients had interposition Gelseal graft and one had repair of the tear in distal aortic arch. The lone patient in group IV had interposition Gelseal graft of thoracoabdominal aorta. The hypothermic circulatory arrest was used in all of them for brain and/or spinal cord protection. Retrograde cerebral perfusion was used in two patients. There were two (13%) operative deaths. One patient died of cerebrovascular accident on eighth post-operative day and second died of inadequate surgical repair. There was one instance of left hemiparesis secondary to an infarct in right frontoparietal region. To conclude, hypothermic circulatory arrest could provide an adequate brain protection for aortic aneurysm surgery. Retrograde cerebral perfusion could be an adjuvant when the anticipated time of hypothermic circulatory arrest is likely to exceed 45 minutes.

Sequential pathological studies in Japanese quails infected experimentally with Aspergillus fumigatus

Intratracheal inoculation of young quail chicks with Aspergillus fumigatus spores resulted in the development of characteristic gross and microscopic lesions. The lesions were restricted to respiratory tract and there was no dissemination of infection to other tissues of the body. Gross changes in lungs and air sacs were observed within 24 hours and continued up to 20 days while in trachea these were noticed from the 3rd to the 9th day post-infection. The lesions, in general, included congestion and focal haemorrhages in the first 2 days followed by the development of varying-sized greyish-white nodules in the lungs, air sacs and trachea. Microscopic changes consisted of congestion, haemorrhages and a diffuse cellular infiltration in the first 2 days followed by granulomatous reaction with well developed granulomas in lungs, air sacs and trachea. Spores and developing hyphae of Aspergillus could be demonstrated in sections from 24 hours to 20 days of infection. Reisolation of the fungus was consistently achieved from the lungs, air sacs and trachea up to 14 days.

Experimental aspergillosis in Japanese quails (Coturnix coturnix japonica). Clinical signs and haematological changes

Intratracheal inoculation of 2-week-old quail chicks with Aspergillus fumigatus resulted in the development of clinical signs within 24 h of infection. These were characterized by anorexia, depression, accelerated respiration and gasping followed by death. The acute course of the disease lasted for 7-10 days followed by recovery in the surviving chicks. The overall mortality during a 6-week observation period was 20%. Although the mean body weight of A. fumigatus infected quail chicks continued to be slightly lower throughout the experiment but the difference, in comparison to controls, was not significant except at 42 days post-infection. There was no appreciable difference in the mean values of Hb, TEC, PCV, MCV, MCH and MCHC between the infected and control chicks at any stage of infection but TLC revealed a leucocytosis from 2-7 days which was the result of increase in the relative percentage of heterophils and decrease in lymphocytes.

Oxypeucedanin, a Major Furocoumarin in Parsley, Petroselinum crispum

Fresh parsley leaves and roots were analyzed by HPLC and photobiological assay for photoactive furocoumarins. Oxypeucedanin ( 7), not previously reported from parsley, was found to be the major component (70-100 ppm wet weight). Although only moderately photoactive, its high concentration in parsley may be partially responsible for contact photodermatitis. Other photoactive compounds, namely 5-MOP ( 2), 8-MOP ( 3), psoralen ( 1), isopimpinellin ( 4) and imperatorin ( 5) were also present and quantified.

Anticonvulsant and antiproteolytic properties of 3,5-disubstituted oxadiazole-2-thiones and their inhibition of respiration in rat brain homogenates

Eight 5-(3,4-methylenedioxyphenyl)-3-arylaminomethyl-1,3,4-oxadiazole-2-thiones were synthesized, characterized by their sharp melting points, elemental analyses, and IR spectra, and evaluated for anticonvulsant activity. All substituted oxadiazole-2-thiones possessed anticonvulsant activity, which was reflected by their ability to provide 10--70% protection against pentylenetetrazol-induced convulsions in mice at 100 mg/kg ip. These compounds inhibited in vitro nicotinamide adenine dinucleotide (NAD)-dependent oxidation of pyruvate, alpha-ketoglutarate, and NADH by rat brain homogenates as well as NAD-independent oxidation of succinate by rat brain homogenates. Antiproteolytic activity of these substituted oxadiazole-2-thiones was reflected by their ability to inhibit trypsin hydrolysis of bovine serum albumin. These results indicated that the inhibition of cellular respiration and antiproteolytic activity of these substituted oxadiazole-2-thiones is not the biochemical basis for their anticonvulsant activity.