Human cerebrospinal fluid contains diverse lipoprotein subspecies enriched in proteins implicated in central nervous system health.

Lipoproteins in cerebrospinal fluid (CSF) of the central nervous system (CNS) resemble plasma high-density lipoproteins (HDLs), which are a compositionally and structurally diverse spectrum of nanoparticles with pleiotropic functionality. Whether CSF lipoproteins (CSF-Lps) exhibit similar heterogeneity is poorly understood because they are present at 100-fold lower concentrations than plasma HDL. To investigate the diversity of CSF-Lps, we developed a sensitive fluorescent technology to characterize lipoprotein subspecies in small volumes of human CSF. We identified 10 distinctly sized populations of CSF-Lps, most of which were larger than plasma HDL. Mass spectrometric analysis identified 303 proteins across the populations, over half of which have not been reported in plasma HDL. Computational analysis revealed that CSF-Lps are enriched in proteins important for wound healing, inflammation, immune response, and both neuron generation and development. Network analysis indicated that different subpopulations of CSF-Lps contain unique combinations of these proteins. Our study demonstrates that CSF-Lp subspecies likely exist that contain compositional signatures related to CNS health.

Mismatch repair protein deficiency assessed by immunohistochemistry in sporadic colorectal carcinoma.

Context: Globally, colorectal carcinoma (CRC) ranks the third most commonly diagnosed malignant disease, one of the leading causes of cancer deaths. Aims: To study the spectrum of clinicopathological characteristics of sporadic colorectal carcinoma and to assess mismatch repair gene deficiency by the expression pattern of the proteins assessed by immunohistochemistry. Setting and Design: Observational study conducted in a tertiary care hospital in West Bengal. Materials and Methods: Fifty-two surgically resected specimens of CRC received from January 2018 to May 2019 were studied for clinical, morphological, MSI status. Statistical Analysis Used: IBM SPSS 23. Results: A total of 50% of the cases belonged to younger and 50% to the older population, with male predominance being 53.8%. The most common histologic type was adenocarcinoma (88.5%). The majority was found to be well-differentiated carcinoma (50%). The majority cases were of the T3 stage accounting to 38.5%. A total of 24 out of 52 cases (46.15%) had an absent expression of at least one mismatch repair (MMR) protein. A significant correlation was found between the young age group and microsatellite instability (MSI) with a P value of 0.001. A significant association was found between MSI and tumor differentiation with P value of 0.018. A significant association was found between MSH6 and histological type with P value of 0.012. A significant association was found between MSI and tumor stage with P value of 0.032. Conclusions: This study shows a significantly higher number of sporadic colon cancers involving the young age group, and younger cases showed significant association with MSI. This alarming trend needs validation by studies involving larger populations and can be helpful prognostically as well as in formulating chemotherapeutic regimens.

Association of overweight and obesity with hypertension, diabetes and comorbidity among adults in Bangladesh: evidence from nationwide Demographic and Health Survey 2017-2018 data.

OBJECTIVES: The study aimed to determine the association of overweight and obesity with hypertension, diabetes and comorbidity among the adults of Bangladesh. STUDY DESIGN: This study used cross-sectional data from the nationally representative Bangladesh Demographic and Health Survey conducted in 2017-2018. The main outcome variables were hypertension, diabetes and comorbidity. Comorbidity was defined as the coexistence of hypertension and diabetes. Overweight and obesity, as measured by body mass index, were the main explanatory variables. The strength of the association was determined using the adjusted multiple logistic regression models. SETTING: Rural and urban areas in Bangladesh. PARTICIPANTS: The study included a total of 11 881 adults (5241 men and 6640 women) aged 18 years or older. RESULTS: The prevalence of hypertension, diabetes and comorbidity among the sample population were 28.5%, 9.9% and 4.5%, respectively. Among the respondents, 20.1% were overweight and 4.1% were obese. The risk of hypertension was 2.47 times more likely in the overweight group (adjusted OR (AOR) 2.47; 95% CI 2.22 to 2.75) and 2.65 times more likely in the obese group (AOR 2.65; 95% CI 2.16 to 3.26) compared with the normal or underweight group. Adults who were overweight and obese had 59% (AOR 1.59; 95% CI 1.37 to 1.84) and 88% (AOR 1.88; 95% CI 1.46 to 2.42) higher odds of having diabetes, respectively, than normal or underweight adults. Moreover, the risk of comorbidity was 2.21 times higher in overweight adults (AOR 2.21; 95% CI 1.81 to 2.71) and 2.86 times higher in obese adults (AOR 2.86; 95% CI 2.09 to 3.91) compared with normal or underweight adults. CONCLUSIONS: Using large-scale nationally representative data, we found that overweight and obesity were significantly associated with hypertension, diabetes and comorbidity. So, nationally representative data can be used for programme planning to prevent and treat these chronic conditions.

Applying Promiscuous RiPP Enzymes to Peptide Backbone N-Methylation Chemistry.

The methylation of peptide backbone amides is a hallmark of bioactive natural products, and it also greatly modifies the pharmacology of synthetic peptides. Usually, bioactive N-methylated peptides are cyclic. However, there is very limited knowledge about how post-translational enzymes can be applied to the synthesis of designed N-methylated peptides or peptide libraries. Here, driven by the established ability of some RiPP enzymes to process diverse substrates, we sought to define catalysts for the in vivo and in vitro macrocyclization of backbone-methylated peptides. We developed efficient methods in which short, synthetic N-methylated peptides could be modified using side chain and mainchain macrocyclases, PsnB and PCY1 from plesiocin and orbitide biosynthetic pathways, respectively. Most significantly, a strategy for PsnB cyclase was designed enabling simple in vitro methods compatible with solid-phase peptide synthesis. We show that cyanobactin N-terminal protease PatA is a broadly useful catalyst that is also compatible with N-methylation chemistry, but that cyanobactin macrocyclase PatG is strongly biased against N-methylated substrates. Finally, we sought to marry these macrocyclase tools with an enzyme that N-methylates its core peptide: OphMA from the omphalotin pathway. However, instead, we reveal some limitations of OphMA and demonstrate that it unexpectedly and extensively modified the enzyme itself in vivo. Together, these results demonstrate proof-of-concept for enzymatic synthesis of N-methylated peptide macrocycles.

Genome-Mining-Based Discovery of the Cyclic Peptide Tolypamide and TolF, a Ser/Thr Forward O-Prenyltransferase.

Cyanobactins comprise a widespread group of peptide metabolites produced by cyanobacteria that are often diversified by post-translational prenylation. Several enzymes have been identified in cyanobactin biosynthetic pathways that carry out chemically diverse prenylation reactions, representing a resource for the discovery of post-translational alkylating agents. Here, genome mining was used to identify orphan cyanobactin prenyltransferases, leading to the isolation of tolypamide from the freshwater cyanobacterium Tolypothrix sp. The structure of tolypamide was confirmed by spectroscopic methods, degradation, and enzymatic total synthesis. Tolypamide is forward-prenylated on a threonine residue, representing an unprecedented post-translational modification. Biochemical characterization of the cognate enzyme TolF revealed a prenyltransferase with strict selectivity for forward O-prenylation of serine or threonine but with relaxed substrate selectivity for flanking peptide sequences. Since cyanobactin pathways often exhibit exceptionally broad substrate tolerance, these enzymes represent robust tools for synthetic biology.

Expanding the chemical space of synthetic cyclic peptides using a promiscuous macrocyclase from prenylagaramide biosynthesis.

Cyclic peptides are excellent drug candidates, placing macrocyclization reactions at the apex of drug development. PatG and related dual-action proteases from cyanobactin biosynthesis are responsible for cleaving off the C-terminal recognition sequence and macrocyclizing the substrate to provide cyclic peptides. This reaction has found use in the enzymatic synthesis of diverse macrocycles. However, these enzymes function best on substrates that terminate with the non-proteinogenic thiazole/thiazoline residue, complicating synthetic strategies. Here, we biochemically characterize a new class of PatG-like macrocyclases that natively use proline, obviating the necessity of additional chemical or biochemical steps. We experimentally define the biochemical steps involved in synthesizing the widespread prenylagaramide-like natural products, including macrocyclization and prenylation. Using saturation mutagenesis, we show that macrocyclase PagG and prenyltransferase PagF are highly promiscuous, producing a library of more than 100 cyclic peptides and their prenylated derivatives in vitro. By comparing our results to known cyanobactin macrocyclases, we catalog a series of enzymes from this family that should synthesize most small macrocycles. Collectively, these data reveal that, by selecting the right cyanobactin macrocyclase, a large array of enzymatically synthesized macrocycles are accessible.

The Biochemistry and Structural Biology of Cyanobactin Pathways: Enabling Combinatorial Biosynthesis.

Cyanobactin biosynthetic enzymes have exceptional versatility in the synthesis of natural and unnatural products. Cyanobactins are ribosomally synthesized and posttranslationally modified peptides synthesized by multistep pathways involving a broad suite of enzymes, including heterocyclases/cyclodehydratases, macrocyclases, proteases, prenyltransferases, methyltransferases, and others. Here, we describe the enzymology and structural biology of cyanobactin biosynthetic enzymes, aiming at the twin goals of understanding biochemical mechanisms and biosynthetic plasticity. We highlight how this common suite of enzymes may be utilized to generate a large array or structurally and chemically diverse compounds.

Draft Genome Sequence of a Polymyxin B-Resistant Sequence Type 195 Clinical Isolate of Acinetobacter baumannii from India.

Acinetobacter baumannii has emerged as a troublesome nosocomial pathogen worldwide. We report here the draft genome sequence of polymyxin B-resistant sequence type 195 (ST195) A. baumannii strain GU71, isolated from a tertiary care hospital in the city of Guwahati, Assam, India.

Profile of colorectal cancer in Eastern India.

Although colorectal cancer is a major cause of concern in the western population, recent studies are showing the incidence and mortality of colorectal cancer to be rapidly rising in Asia. The present study is an insight into the epidemiological profile of colorectal cancer of a representative Eastern Indian population. Over a period of three years, all histologically proved patients with colorectal cancer were assessed for age, sex, body mass index, dietary habits, socioeconomic status and stage of disease. Of a total of 168 patients male to female ratio was 1.7:1.The mean age of presentation was 47.01 years. Although colorectal cancer has been known as a disease of sedentary obese men, 41.66% of the patients were from a low socioeconomic rural set-up and 40.47% were involved in heavy physical labour with only 15% of being obese; 62% patients were harbouring a locally advanced disease at the time of presentation. The epidemiological pattern of colorectal cancer in India is different from that of the west as regards to earlier age of presentation, prevalence in low socio economic class with low fat diet and scanty meat intake.