Molecular biology of opioid receptors: recent advances

Endogenous opioid peptides and opiates like morphine produce their pharmacological effects through the membrane bound opioid receptors. These receptors belong to a superfamily of G-protein-coupled receptors, all of which possess seven membrane-spanning regions. Structure-activity relationship studies of opioids opened up new avenues for the pharmacological characterization of the opioid receptors. As a further advancement in this direction, molecular cloning has led to the identification of three different types of opioid receptors -- OP1 (delta), OP2 (kappa) and OP3 (mu) -- thereby supporting the results of earlier pharmacological studies which postulated their existence. The three opioid receptors are highly homologous. Consequent to the development of highly specific and selective agonists and antagonists, it was proposed that the three types of opioid receptors could be further categorized into different subtypes. However, the molecular biology data generated so far do not support the presence of the various subtypes of the three well-characterized opioid receptors. Recent strides towards the advancement of our knowledge relating to the molecular biology of these receptors have been reviewed in this article.

Immunomodulatory activity of met-enkephalin and its two potent analogs

The effects of Met-enkephalin (Met-Enk), a delta receptor binding opioid peptide, and its more stable synthetic analogs, Tyr-D-Ala-Gly-MePhe-Met-NHC3H7-iso (1), Tyr-D-Ala-Gly-MePhe-Gly-NHC3H7-iso (2) and Tyr-D-Ala-Gly-MePhe-Gly-NHCH2C6H5 (3), on human T-cell transformation and natural killer (NK) cell cytotoxicity have been evaluated. Analogs 1 and 2 have been found to be as potent as Met-Enk in stimulating T-cell transformation and augmenting NK cell cytotoxicity. Analog 3 had no effect on T-cell transformation and NK cell cytotoxicity. Proliferative response was measured by 3H-thymidine uptake after 5 days of incubation. The kinetics of the T-cell transformation response (peak 5th day) is similar to those for in vitro T-cell responses to specific antigens rather than via polyclonal activation.

Endometrial Receptivity During the Preimplantation Period: A Narrative Review

Endometrial receptivity is a complex and critical process fundamental to achieving a successful pregnancy. While researchers have made significant strides in understanding the underlying mechanisms governing endometrial receptivity, effective diagnostic and therapeutic strategies remain scarce. This review article aims to elucidate the various factors that contribute to endometrial receptivity, including the hormonal regulation and molecular mechanisms that govern this process, as well as potential biomarkers for assessing endometrial receptivity. One of the major challenges in identifying reliable biomarkers for endometrial receptivity is the intricate nature of the process itself. Nonetheless, recent advances in transcriptomic and proteomic technologies have identified several candidate biomarkers that could potentially enhance our ability to predict endometrial receptivity. Furthermore, emerging technologies such as single-cell RNA sequencing and mass spectrometry-based proteomics hold great promise for providing novel insights into the molecular mechanisms underlying endometrial receptivity. Despite the lack of reliable biomarkers, various therapeutic strategies have been proposed to improve endometrial receptivity. One promising approach involves the transplantation of mesenchymal stem cells (MSCs), which have been shown to increase endometrial thickness and receptivity in both animal models and clinical trials. Growth factors, cytokines, and exosomes derived from MSCs and other cell types may also have therapeutic potential for addressing endometrial dysfunction.

Delta-opioid receptor antagonist inhibits immunomodulation by Met-enkephalin analogs

The methionine-enkephalin (Met-enkephalin, Tyr-Gly- Gly-Phe-Met) analogs Tyr-D-Ala-Gly-MePhe-Met NHC(3)H(7)-iso (1) and Tyr-D-Ala-Gly-MePhe-Gly-NHC(3)H(7)-iso (2) have been shown to enhance human T cell proliferation in in vitro treatment. Their immunomodulatory activities were completely blocked by naloxone, an opioid antagonist. Now we demonstrate that a selective delta-opioid receptor antagonist, ICI-174,864, completely blocks enhancement of T cell proliferation by analogs (1) and (2). The T cell-stimulatory effect was only partially inhibited by the mu-receptor-selective antagonist, beta-funaltrexamine hydrochloride. The kappa-opioid receptor antagonist, nor-binaltorphimine dihydrochloride, showed no effect on T cell-proliferation stimulated by analogs (1) and (2). These observations suggest that analogs (1) and (2) of Met-enkephalin stimulate T cell proliferation predominantly via delta-opioid receptor present on T cells.

Immunomodulation by two potent analogs of met-enkephalin

Met-enkephalin (Tyr-Gly-Gly-Phe-Met) and its more stable analogs, Tyr-D-Ala-Gly-MePhe-Met-NHC3H gamma-iso (1) and Tyr-D-Ala-Gly-MePhe-Gly-NHC3H gamma-iso (2) significantly enhanced human T-cell proliferation in vitro after 5 days of incubation in the absence of mitogen. The activity was completely inhibited by naloxone, an opioid antagonist. These peptides significantly enhanced human active T-cell rosette (CD2R) also on in vitro treatment. Furthermore, these analogs stimulated interleukin-2 production by human peripheral blood mononuclear cells in vitro which was completely inhibited by naloxone. These observations suggest that human T-cells bear receptors for Met-enkephalin on their surface. Such findings may provide a link between the central nervous system and the immune system.

Immunomodulating activity of analogs of noninflammatory fragment 163-171 of human interleukin-1beta

The synthetic nonapeptide Val-Gln-Gly-Glu-Glu-Ser-Asn-Asp-Lys corresponding to the amino acid sequence 163-171 of human interleukin-1beta (IL-1beta) has been reported to retain considerable immunostimulatory activity of the native protein without the induction of the inflammatory or pyrogenic responses. Two lipophilic derivatives of this nonapeptide, one having a lauroyl residue (1) and the other having a palmitoyl residue (2) at the N-terminus of the peptide, and a more stable analog carrying D-Val residue at position 1 of the peptide (3) were synthesized with a view to find out if these structural modifications had a favorable effect on in vitro mouse thymocyte proliferation and IL-1 dependent inhibition of A375 cells. We have found that analogs (1) and (2) are active in both the tests like the parent nonapeptide. The lipophilic analog (2) is in fact, effective at a lower dose as compared to the parent nonapeptide in mouse thymocyte proliferation assay. Although the analog (3) has the ability to inhibit A375 cells, it does not stimulate mouse thymocyte proliferation in vitro. The IL-1beta fragment (163-171) and the analog (2) were further compared for their effects on pyrogenicity, blood glucose level, acute phase response and radioprotection. Unlike IL-1beta, its fragment (163-171) and the analog (2) do not induce pyrogenicity and any of the acute phase related changes such as the increase in C-reactive protein and hypoglycemia following their administration in Balb/c mice. We have found that 40% of animals treated with analog (2) survive more than 21 days after lethal irradiation as compared to 20% survivors in groups treated with recombinant IL-1beta or its nonapeptide fragment (163-171), under conditions when all the control animals died within 10 days. This study may help in designing small peptides which may be more effective and stable.

Rituximab in Pemphigus Vulgaris: A Review of Monoclonal Antibody Therapy in Dermatology

Pemphigus vulgaris (PV) is a rare autoimmune blistering disorder that primarily affects the skin and mucous membranes. Conventional treatments for PV, such as corticosteroids and immunosuppressive agents, have limitations in terms of efficacy and long-term safety. Monoclonal antibody therapy, specifically rituximab, has emerged as a promising therapeutic approach in the management of PV. This review article provides a comprehensive overview of rituximab in the treatment of PV, with a focus on its efficacy, safety profile, and immunological mechanisms of action. The article begins with an introduction to PV and the significance of monoclonal antibody therapy in dermatology. It then explores the clinical presentation and underlying immune-mediated mechanisms of PV, highlighting the autoimmune nature of the disease. The rationale for using monoclonal antibody therapy, particularly rituximab, in PV is discussed, emphasizing the limitations of conventional treatments and the concept of targeted therapy. The review delves into the efficacy and safety of rituximab based on clinical studies, evaluating disease remission rates, duration, and relapse rates. Furthermore, the immunological effects of rituximab, including B-cell depletion and modulation of the immune response, are explored in detail. Comparisons between rituximab and conventional treatment modalities in PV are made, assessing clinical outcomes, safety profiles, and long-term efficacy. Challenges and considerations in rituximab therapy are discussed, including factors influencing its efficacy, optimal dosing, treatment duration, and the need for maintenance therapy.

Diastolic Dysfunction of the Left Ventricle in a Prediabetic Population from Rural Central India

According to a growing body of research, in people with type 2 diabetes mellitus (T2DM), cardiovascular diseases are a leading cause of mortality. Many studies have sought to understand the many pathways that may play a role in CVD in diabetics in a significant way. According to research, pat had a much higher overall morbidity and mortality rate. The culprits are hyperglycemia-induced macrovascular diseases, autonomic neuropathy, and generally diabetic cardiomyopathy, which is quite significant. Diabetic people might be diagnosed with cardiomyopathy even if they generally are initially asymptomatic and show no clinical indications of the disease, or so they essentially thought. Echocardiography provides the opportunity to measure systolic and diastolic function, which is explicitly fairly significant. A significant risk factor for developing diabetes appears to be prediabetes with the risk of conversion is approximately 70% in the next ten years, with similar microvascular and cardiovascular consequences to diabetes. Immunological factors, Cytokines, advanced glycosylation end-product accumulation and oxidative stress, a standard processes involved. Diastolic dysfunction alters diastolic filling and increases isovolumetric relaxation time in diabetic patients. One of the independent markers for assessing the propensity of developing Cardiovascular disease in a diabetic population is Insulin Resistance. On the other hand, normotensive patients have been linked to left ventricular dysfunction, even when omitting those with coronary artery disease (CAD), which is quite significant for all intents and purposes. According to experts at the Indian Institute of Cardiology (ICC) in Bangalore, even people with normal blood pressure and prediabetes exhibit asymptomatic diastolic dysregulation.