Rhodium-Catalyzed Regioselective C3Ar Functionalization of Tyrosines with Maleimides and Its Late-Stage Peptide Exemplification.

Pyridyloxy-directed Rh(III)-catalyzed regioselective C3Ar-H alkenylation of protected tyrosines was achieved with N-aryl and N-alkyl maleimides, furnishing a series of maleimide-appended tyrosine-based unnatural amino acids in good yields. Further, the late-stage exemplification of the strategy was successfully accomplished on tyrosine-containing dipeptides, tripeptides, and tetrapeptides in moderate reactivity. Also, the chemical applications of the strategy were successfully executed toward nailing tyrosine with other amino acids via a maleimide linker and intramolecular hydroarylation to produce tyrosine-centered stapled products and succinimide-glued macrocyclized products, respectively.

Synthesis of modified bile acids via palladium-catalyzed C(sp3)-H (hetero)arylation.

A Pd(II)-catalyzed strategy for the diastereo- and regioselective (hetero)arylation of unactivated C(sp3)-H bonds in bile acids is accomplished with aryl and heteroaryl iodides under solvent-free conditions using the 8-aminoquinoline auxiliary as a directing group. This methodology demonstrated excellent functional group tolerance with respect to aryl/heteroaryl iodides on O-protected N-(quinolin-8-yl)cholyl/deoxycholyl amides to afford ß-C(sp3)-H (hetero)arylated products in good-to-excellent yields. Moreover, the 8-aminoquinoline (AQ) auxiliary can easily be removed to obtain modified bile acids.

Role of Endoscopic Ultrasound in Predicting Solid Pancreatic Lesions Using Strain Ratio and Elastography.

Background: Despite advancement in imaging techniques, the diagnosis of solid pancreatic lesions (SPLs) remains challenging. The latest advancement in elastography permits the quantitative measurements of the average elasticity of a lesion. Therefore, our main aim of this study was to determine the utility of endoscopic ultrasound-guided elastography (EUS-EG) and strain ratio (EUS-SR) in predicting SPLs. Materials and methods: This cross-sectional study was performed at the Department of Hepatogastroenterology, Sindh Institute of Urology and Transplantation. All patients with radiological diagnosis of SPLs underwent EUS-EG, followed by strain ratio (SR) measurement and targeted pancreatic fine needle lesion biopsy (FNB). Area under the receiver operating curve (AUROC) was obtained for SR and combined elastography and SR and at an optimal cutoff, diagnostic accuracy was obtained in predicting the nature of SPLs. Results: A total of 52 patients were included in this study. Out of them, 32 (61.5%) patients were males while 20 (38.5%) were females. The mean age was 50.8 ± 12.5 years. Twenty-four (46.2%) patients had malignant pancreatic lesions. Among malignant lesions, the most common etiology was pancreatic adenocarcinoma seen in 18 (34.6%) patients. Out of 28 (53.8%) patients with benign lesions, 14 (26.9%) patients had inflammatory disease. Area under the receiver operating curve was obtained for both SR alone and SR combined with elastography score in differentiating benign from malignant SPLs which was 0.832 (p-value < 0.001) for SR alone and a slightly higher for combined SR with elastography (AUROC-0.839)(p-value < 0.001). At an optimal cutoff of SR of >17, the sensitivity was 94.8% and the diagnostic accuracy was 74% in predicting SPLs. While, when SR and elastography were combined together, the sensitivity increased to 96% with a diagnostic accuracy of 75%. Conclusion: Combined EUS-EG and SR were accurate in diagnosing malignant pancreatic lesions with a diagnostic accuracy of 75% providing additional diagnostics information before biopsy. However, multicentric studies with larger sample sizes are required for the validation of our results to determine the utility and diagnostic accuracy of EUS-SR in defining the characteristic of pancreatic lesions. How to cite this article: Bajaj K, Yaseen T, Tasneem AA, et al. Role of Endoscopic Ultrasound in Predicting Solid Pancreatic Lesions Using Strain Ratio and Elastography. Euroasian J Hepato-Gastroenterol 2023;13(1):1-4.

Tandem Transformation of Indazolones to Quinazolinones through Pd-Catalyzed Carbene Insertion into an N-N Bond.

Serendipitous and expedite transformation of 1-aryl- and 2-aryl-1,2-dihydro-3H-indazol-3-ones to 1,2-di(hetero)aryl- and 2,3-di(hetero)aryl-2,3-dihydroquinazolin-4(1H)-ones, respectively, was achieved in high efficiency by reacting them with aldehydic N-tosylhydrazones. The protocol proceeded through a cascade process involving base-mediated Pd-carbenoid generation by the decomposition of N-tosylhydrazones, nucleophilic attack of indazolone on the Pd-carbenoid complex, and intramolecular ring expansion via N-N bond cleavage. The utility of the strategy is demonstrated toward the synthesis of bioactive NPS 53574, a calcium receptor antagonist.

Rhodium-Catalyzed Annulation of Vinylated Tyrosines with Internal Alkynes to Access Oxepine-Mounted Unnatural Tyrosines and Its Peptide Late Stage Functionalization.

A Rh(III)-catalyzed [5+2] annulation of vinyl tyrosines with symmetrical and unsymmetrical internal alkynes was achieved, furnishing a series of oxepine-mounted tyrosine-based unnatural amino acids. In addition, the chemical applicability of the developed strategy was exemplified by stapling amino acid/peptide-appended alkynes with vinyl tyrosines and late stage functionalization of tyrosine-containing dipeptides and tripeptide with internal alkynes.

A Tertiary Care Center's Experience with Clinicopathological Characteristics of Gallbladder Carcinoma in Our Population.

Introduction: Gallbladder cancer (GBC) is the most common malignant biliary tract tumor with the shortest survival from the time of diagnosis. This poor prognosis is due to the destructive biologic behavior of GBC, lack of sensitive screening tests for early detection, and vague nature of first presentation. Here in this study, we will evaluate the baseline characteristics of the patients presenting with gallbladder carcinoma in our population. Materials and methods: This retrospective study was conducted in the Department of Gastroenterology at Sindh Institute of Urology and Transplantation (SIUT), Karachi. Patient data were compiled and composed from the in-patient health records, radiology, and operational records. Those patients with suspicion of GBC, but negative at histology, or patients having inconclusive radiologic findings, were excluded. Baseline characteristics were recorded. Results were presented as means ± SD for quantitative data or as numbers with percentages for qualitative data. Continuous variables were analyzed using the Student's t-test, while categorical variables were analyzed using the Chi-square test. A p-value of <0.05 was considered statistically significant. Results: A total of 162 patients were included in our study. Among them, 101 (62.3%) were females. Hypertension was the most common comorbid illness noted in 29 (17.9%) patients while 91 (56.2%) patients had no concurrent comorbidities. Most common risk factor for carcinoma of gallbladder was gallstones seen in 106 (65.1%) patients. The most common presenting complaint was combination of obstructive jaundice, weight loss with right hypochondrial pain seen in 66 (40.7%) patients. On CT abdomen, direct liver infiltration without lymphovascular invasion was noted in 77 (47.5%) patients followed by liver infiltration along with lymphovascular invasion in 26 (16%) patients and distant metastasis in 24 (14.8%) patients. On gallbladder (GB) mass biopsy, 58 (35.8%) patients had well-differentiated, 46 (28.4%) had moderately differentiated, while 33 (20.4%) had poorly differentiated adenocarcinoma. Of 162 patients, 103 (63.6%) patients underwent endoscopic retrograde cholangiopancreatography (ERCP). The most common finding on ERCP was proximal common bile duct (CBD) stricture with intrahepatic biliary system dilatation which was noted in 95 (58.6%) patients. Percutaneous transhepatic cholangiography (PTC) was performed only in 9 (5.6%) patients. Seventeen (10.5%) patients were managed by simple cholecystectomy, 39 (24.1%) patients underwent extended cholecystectomy, 14 (8.6%) patients underwent chemotherapy, while 102 (56.8%) patients were given palliative management. When followed for 1 year, 101 (62.3%) patients died within 6 months. Conclusion: The baseline characteristics, biopsy findings, modes of treatment, and rates of 1 year mortality were studied in patients with gallbladder carcinoma in our population. Advanced age, high white blood cell counts, and serum bilirubin at presentation with low lymphocyte count and presence of comorbid illnesses were the factors independently associated with increased mortality in patients with gallbladder carcinoma. However, further studies with large sample size and stratification with respect to age, gender, and different variables can be done in terms of mortality in patients with gallbladder carcinoma. How to cite this article: Akbar N, Yaseen T, Muhammad A, et al. A Tertiary Care Center's Experience with Clinicopathological Characteristics of Gallbladder Carcinoma in Our Population. Euroasian J Hepato-Gastroenterol 2022;12(1):35-39.

A Practitioner's Toolkit for Polycystic Ovary Syndrome Counselling.

Polycystic ovary syndrome (PCOS), a frequently occurring health issue, has a significant effect on the cosmetic, metabolic, psychosocial and fertility aspects of women. A multidisciplinary team approach based on the core pillars of screening, assessment and counselling to detect, prevent and treat physiological and psychological issues in PCOS is very essential. Women are treated medically, but the psychosocial part is often forsaken. Hence, counselling forms an integral part of PCOS management that enables enhanced clinical outcomes and patient satisfaction. Digital tools and PCOS support groups have built an opportunity for physicians to create awareness, help timely diagnosis and overcome PCOS symptoms. The absence of clear guidelines to tackle the often less discussed aspects of PCOS warrants the need for consensus on PCOS counselling. This review summarizes the biopsychosocial health, clinical assessment and treatment strategies of PCOS and associated co-morbidities. The review article will discuss the clinician's role in patient education with the special focus on counselling of females with PCOS regardless of age group.

Ruthenium-catalyzed (spiro)annulation of N-aryl-2,3-dihydrophthalazine-1,4-diones with quinones to access pentacyclic spiro-indazolones and fused-cinnolines.

Ru(II)-catalyzed strategies were developed for the [4 + 1] and [4 + 2] oxidative coupling between N-aryl-2,3-dihydrophthalazine-1,4-diones and 1,4-benzoquinones, achieving spiro-indazolones and fused-cinnolines, respectively. Mild, aerobic and external oxidant-free conditions, as well as the use of a ruthenium catalyst for such (spiro)annulative strategies with quinones over reported Rh/Ir-catalyts, underline the rewards of the disclosed protocols.

Fluorescent glutamine and asparagine as promising probes for chemical biology.

Fluorescent probes have become valuable tools in chemical biology, providing interesting inferences for unfolding the complexities of natural biochemical processes. In this study, we report the synthesis and characterization of fluorescent labelled glutamine (Gln) and asparagine (Asn) derivatives via traceless Staudinger ligation, which exhibited high fluorescence quantum yields, excellent photostabilities and emission of blue fluorescence in the visible region. The successful permeation of these fluorescent amino acids into cellular components proved their potential as fluorescent probes for chemical biology.

Expansion of Phosphane Treasure Box for Staudinger Peptide Ligation.

A smooth traceless ligation strategy using an air-stable phosphane probe (2-(diphenylphosphanyl)phenyl)methanol as a C-terminus activator has been demonstrated at simple and sterically hindered amino acid junctions (Gly, Ala, Trp, Glu). This Staudinger peptide ligation proceeds via formation of a seven-membered transition state to afford di-, tetra-, and pentapeptides in 78-95% yields. The experimental results of ligation at Gly junction and regioselective ligation at Glu junction were theoretically studied by computational calculations. These findings established the versatile behavior of our synthesized phosphane probe for Staudinger peptide ligation toward synthesizing peptides and proteins of choice.

Aziridine based electrophilic handle for aspartic acid ligation.

A one-pot ligation strategy at aspartic acid junctions has been developed by successfully incorporating aziridin-2,3-dicarboxylate to the N-side of a peptide fragment, affording N-aziridine appended peptides, which were ligated in solution phase with a variety of small peptide thio acids to afford native peptides, following a ring-opening/peptidyl migration/desulfurization strategy. The reaction proceeds in a highly regiospecific manner, and provides short native peptides in good isolable yields. A variety of aspartame based peptides were synthesized to showcase the generality of this aziridine based ligation. Computational studies have also been performed to obtain insight about the reaction pathway.

Aziridine-Mediated Ligation at Phenylalanine and Tryptophan Sites.

An efficient approach towards peptide synthesis that allows easy access to variety of small peptides via one-pot aziridine-mediated ligation/desulfurization strategy has been described. The protocol afforded a library of phenylalanine- and tryptophan-containing α-peptides in good yields by regioselective ring-opening of aziridine-3-aryl-2-carboxylates with peptide thioacids, followed by desulfurization.

Traceless reductive ligation at a tryptophan site: a facile access to ß-hydroxytryptophan appended peptides.

An efficient methodology for cysteine-free ligation at a tryptophan (Trp) site is described. A chemically active scaffold, ß-hydroxy-α-azidotryptophan, has been synthesized and explored towards the synthesis of a series of ß-hydroxytryptophan appended native peptides in good yields via one-pot reductive traceless ligation of ß-O-peptidyl-α-azidotryptophan involving an O → N peptidyl transfer strategy. Pre-organized conformational analysis and reaction energy pathway based theoretical studies further supported the experimental findings on the chemical structure stability of ligated products.

Introduction of histidine units using benzotriazolide activation.

N(α) -Boc-N(im) -(4-toluenesulfonyl-l-histidylbenzotriazole) enables convenient acylation of N-, O-, S-, and C-nucleophiles with no detectable racemization. We report efficient syntheses of novel histidine-containing di-, tri-, and tetra-peptides and models for the preparation of potentially biologically active histidine N-, O-, S-, and C-conjugates.

Quinine bis-conjugates with quinolone antibiotics and peptides: synthesis and antimalarial bioassay.

Benzotriazole-mediated syntheses led to novel bis-conjugates of quinine with quinolone antibiotics and amino acid linkers which were successfully prepared by two alternative routes with excellent yields and retention of chirality. These bis conjugates retain in vitro antimalarial activity with IC(50) values ranging from 12 to 207 nM, similar to quinine itself.

Study of chemical ligation via 17-, 18- and 19-membered cyclic transition states.

Unprotected S-acylated cysteine isopeptides containing α-, ß- or γ-amino acid units have been synthesized, and their conversion to native hexapeptides by S- to the N-terminus ligations involving 17-, 18- and 19-membered cyclic transition states have been demonstrated both experimentally and computationally to be more favorable than intermolecular cross-ligations.

Syntheses of chiral N-(protected) tri- and tetrapeptide conjugates.

Cbz-(protected)-tri- and tetrapeptide conjugates with steroids, sugars, terpenes, and heterocycles were prepared using Cbz-(protected)-tri- and tetrapeptidoylbenzotriazoles as active intermediates.

Efficient syntheses of thiadiazole peptides.

Novel N-(Cbz-aminoacyl)thiosemicarbazides 3a-c were cyclized by treatment with sulfuric acid to give 1,3,4-thiadiazoles 4a-c. Compounds 4a-c reacted with N-(Cbz-aminoacyl)- and -dipeptidoylbenzotriazoles to afford chirally pure 1,3,4-thiadiazol-2-yl-substituted amino acids 6a-c and dipeptides 7a-c.

Amino acyl conjugates of nitrogen heterocycles as potential pharmacophores.

2-Methyl- and 4-methylpyridine and 2-methylquinoline are converted by benzotriazole-activated (Cbz)-protected amino acids into chiral potential novel pharmacophore aminoacyl conjugates (33-53%).

Synthesis of acridinyl-thiazolino derivatives and their evaluation for anti-inflammatory, analgesic and kinase inhibition activities.

Variety of N-(4-phenyl-3-(2',3',4'(un)substituted phenyl)thiazol-2(3H)-ylidene)-2,4(un)substituted acridin-9-amine (4a-o) and 1-[(2,4-(un)substituted acridin-9-yl)-3-(4-phenyl-3-(2',3',4'(un)substituted phenyl)thiazol-2(3H)-ylidene)]isothiourea (5a-h) derivatives have been synthesized by condensation of 4-phenyl-3-(2',3',4'(un)substituted phenyl)thiazol-2(3H)-imine (3a-g) with 9-chloro-2,4-(un)substituted acridine (1a-c) and 9-isothiocyanato-2,4-(un)substituted acridine (2a-d), respectively. All these compounds were characterized by correct 1H NMR, FT-IR, MS and elemental analyses. These compounds were screened for anti-inflammatory, analgesic and kinase (CDK1, CDK5 and GSK3) inhibition activities. Some compounds exhibited good anti-inflammatory (25-32%) and potent analgesic (50-75%) activities, at 50 mg/kg p.o. A compound, 4o (R1 = H, R2 = OCH3, R3 = CH3, R4 = CH3, R5 = H) exhibited moderate CDK1 (IC50 = 8.5 microM) inhibition activity.