Is Combining Two Different Routes of TXA Administration an Effective Blood Conserving Strategy for Total Knee Arthroplasty.

Aim: To evaluate the efficacy of combined use of pre-operative oral and post-operative intravenous (IV) tranexamic acid (TXA) as an effective blood conserving regimen in total knee arthroplasty (TKA) and compare its outcome with other modes of TXA administration. Patients and Methods: A prospective observational study was conducted on 25 patients with osteoarthritis knee undergoing TKA. Patients were given 1950 mg of oral TXA pre-operatively and 15 mg/kg of IV TXA post-operatively before tourniquet deflation. The outcome of the study in terms of peri-operative (intra-operative and post-operative) blood loss estimation, drain output, percentage fall in haemoglobin, and knee HSS scores pre-operatively and on subsequent follow-up were compared with the outcome of previous studies conducted in the same institution with intra-operative topical TXA administration, pre-operative oral TXA administration and without TXA administration. Results: The mean drain volume was 307.30 ± 148.00 ml and 22 (88%) patients had a drain volume less than 500 ml. The mean post-operative haemoglobin value was 10.53 ± 1.75 g/dl. It was observed that 18 (72%) of patients had up to 15% fall in haemoglobin. The mean percentage fall was 11.92%. In this study, 22 (88%) patients did not require any blood transfusion. Mean blood loss was 369.6 ± 159.96 ml. Maximum patients had less than 500 ml blood loss. No incidence of implant loosening, infection or wound gaping, clinically evident DVT/pulmonary thromboembolism was observed in the present study. We analysed total modified HSS knee score from pre-operative to 6 months follow-up using multi-group repeated measures analysis of variance (ANOVA), the difference in total modified HSS knee score between all the duration was observed to be highly significant (p < 0.001). Discussion: Combined administration of pre-operative oral and post-operative IV TXA is a safe and effective blood-conserving strategy in patients undergoing TKA along with the use of tourniquet. The outcome in terms of post-operative blood loss and drain output and the knee HSS score is comparable to the other modes of administration. Supplementary Information: The online version contains supplementary material available at 10.1007/s43465-023-00875-w.

Calcium imaging: a technique to monitor calcium dynamics in biological systems.

Calcium ion (Ca2+) is a multifaceted signaling molecule that acts as an important second messenger. During the course of evolution, plants and animals have developed Ca2+ signaling in order to respond against diverse stimuli, to regulate a large number of physiological and developmental pathways. Our understanding of Ca2+ signaling and its components in physiological phenomena ranging from lower to higher organisms, and from single cell to multiple tissues has grown exponentially. The generation of Ca2+ transients or signatures for various stress factor is a well-known mechanism adopted in plant and animal systems. However, the decoding of such remarkable signatures is an uphill task and is always an interesting goal for the scientific community. In the past few decades, studies on the concentration and dynamics of intracellular Ca2+ are significantly increasing and have become a trend in modern biology. The advancement in approaches from Ca2+ binding dyes to in vivo Ca2+ imaging through the use of Ca2+ biosensors to achieve spatio-temporal resolution in micro and milliseconds range, provide us phenomenal opportunities to study live cell Ca2+ imaging or dynamics. Here, we describe the usage, improvement and advancement of Ca2+ based dyes, genetically encoded probes and sensors to achieve extraordinary Ca2+ imaging in plants and animals.

Re-inventing the straight incision with a single central suture in manual small-incision cataract surgery to minimize surgically induced astigmatism.

Purpose: To calculate the surgically induced astigmatism (SIA) in MSICS through a superiorly placed straight scleral incision closed with a single, central, perpendicular 10-0 polyamide suture and to document any suture-related complaints and complications. Methods: A retrospective, hospital-based study was carried out in 50 cases of uncomplicated senile cataract (>50 year) with nuclear sclerosis ≥ grade 4, "with the rule" astigmatism who underwent MSICS through a superior, straight incision with a single, central, perpendicular 10-0 nylon suture. Patients with "against the rule" astigmatism, keratoconus, pre-existing corneal opacity, astigmatism >2D, distorted or oblique mires, and previous ocular surgeries and unwilling to participate were excluded. Results: The mean age of the patients was 64.81 + 2.824 years, with a male: female ratio of 1.38:1. The mean SIA at day 7, week 6, and 12 weeks was 0.539 + 0.118, 0.529 + 0.134, and 0.524 + 0.129, respectively. Only 6 patients (12%) complained of foreign body sensation. No patient developed any suture-related complications. Conclusion: SIA is significantly reduced in straight incision by applying a single, central, and perpendicular 10-0 polyamide suture, as compared to a straight incision without a suture.

New insights into the disintegration mechanism and disintegration profiling of rapidly disintegrating tablets (RDTs) by thermal imaging.

In current studies, the disintegration process of tablets has been studied by thermal imaging. The study covers two major aspects; first, new revelations in the mechanism of tablet disintegration, and second, the development of disintegration test as a multi-point test by new thermometric and non-thermometric methods. The study has been carried out on fexofenadine rapidly disintegrating tablets (FEX RDTs) in a dark room cabinet fitted with a Fluke thermal imager and using water as the disintegration medium. The studies exhibit the existence of endothermic peaks during the early penetration of water in FEX RDTs. These endotherms are prominent at the starting point when the disintegration has just started, or the tablet has been just exposed to the water. Such endotherms have not been reported earlier for tablets and can be considered as a part of the wicking mechanism during disintegration. In later stages, when the water has completely wet the tablet, the endotherms are superimposed by exotherms. The endotherms or exotherms have also been used as a measurement of disintegration in the form of a new thermometric parameter, "area under temperature curve" (AUTC). Non-thermometric disintegration profiling by residual and subtraction methods is also performed. Among these, disintegration by the residual method, i.e., disintegration (residual) is newly introduced. In the end, the principal component analysis (PCA) describes the relationship between various disintegration methods, particle size distribution, and dissolution. PCA reveals that AUTC is the best method for studying the disintegration behavior of FEX RDTs.

Intermolecular interactions in staphylokinase-plasmin(ogen) bimolecular complex: function of His43 and Tyr44.

Staphylokinase (SAK) forms a 1:1 stoichiometric complex with human plasmin (Pm) and switches its substrate specificity to generate a plasminogen (Pg) activator complex. Site-directed mutagenesis of SAKHis43 and SAKTyr44 demonstrated the crucial requirement of a positively charged and an aromatic residue, respectively, at these positions for optimal functioning of SAK-Pm activator complex. Molecular modeling studies further revealed the role of these residues in making cation-pi and pi-pi interactions with Trp215 of Pm and thus establishing the crucial intermolecular contacts within the active site cleft of the activator complex for the cofactor activity of SAK.

Enhanced plasminogen activation by staphylokinase in the presence of streptokinase beta/betagamma domains: plasminogen kringles play a role.

Presence of isolated beta or betagamma domains of streptokinase (SK) increased the catalytic activity of staphylokinase (SAK)-plasmin (Pm) complex up to 60%. In contrast, fusion of SK beta or betagamma domains with the C-terminal end of SAK drastically reduced the catalytic activity of the activator complex. The enhancement effect mediated by beta or betagamma domain on Pg activator activity of SAK-Pm complex was reduced greatly (45%) in the presence of isolated kringles of Pg, whereas, kringles did not change cofactor activity of SAK fusion proteins (carrying beta or betagamma domains) significantly. When catalytic activity of SAK-microPm (catalytic domain of Pm lacking kringle domains) complex was examined in the presence of isolated beta and betagamma domains, no enhancement effect on Pg activation was observed, whereas, enzyme complex formed between microplasmin and SAK fusion proteins (SAKbeta and SAKbetagamma) displayed 50-70% reduction in their catalytic activity. The present study, thus, suggests that the exogenously present beta and betagamma interact with Pg/Pm via kringle domains and elevate catalytic activity of SAK-Pm activator complex resulting in enhanced substrate Pg activation. Fusion of beta or betagamma domains with SAK might alter these intermolecular interactions resulting in attenuated functional activity of SAK.

Function of the 90-loop (Thr90-Glu100) region of staphylokinase in plasminogen activation probed through site-directed mutagenesis and loop deletion.

Staphylokinsae (SAK) forms a bimolecular complex with human plasmin(ogen) and changes its substrate specificity by exposing new exosites that enhances accession of substrate plasminogen (PG) to the plasmin (Pm) active site. Protein modelling studies indicated the crucial role of a loop in SAK (SAK 90-loop; Thr(90)-Glu(100)) for the docking of the substrate PG to the SAK-Pm complex. Function of SAK 90-loop was studied by site-directed mutagenesis and loop deletion. Deletion of nine amino acid residues (Tyr(92)-Glu(100)) from the SAK 90-loop, resulted in approximately 60% reduction in the PG activation, but it retained the ability to generate an active site within the complex of loop mutant of SAK (SAKDelta90) and Pm. The preformed activator complex of SAKDelta90 with Pm, however, displayed a 50-60% reduction in substrate PG activation that remained unaffected in the presence of kringle domains (K1+K2+K3+K4) of PG, whereas PG activation by SAK-Pm complex displayed approximately 50% reduction in the presence of kringles, suggesting the involvement of the kringle domains in modulating the PG activation by native SAK but not by SAKDelta90. Lysine residues (Lys(94), Lys(96), Lys(97) and Lys(98)) of the SAK 90-loop were individually mutated into alanine and, among these four SAK loop mutants, SAK(K97A) and SAK(K98A) exhibited specific activities about one-third and one-quarter respectively of the native SAK. The kinetic parameters of PG activation of their 1:1 complex with Pm indicated that the K(m) values of PG towards the activator complex of these two SAK mutants were 4-6-fold higher, suggesting the decreased accessibility of the substrate PG to the activator complex formed by these SAK mutants. These results demonstrated the involvement of the Lys(97) and Lys(98) residues of the SAK 90-loop in assisting the interaction with substrate PG. These interactions of SAK-Pm activator complex via the SAK 90-loop may provide additional anchorage site(s) to the substrate PG that, in turn, may promote the overall process of SAK-mediated PG activation.