Structurally Altered, Not Wild-Type, Pentameric C-Reactive Protein Inhibits Formation of Amyloid-ß Fibrils.

The structure of wild-type pentameric C-reactive protein (CRP) is stabilized by two calcium ions that are required for the binding of CRP to its ligand phosphocholine. CRP in its structurally altered pentameric conformations also binds to proteins that are denatured and aggregated by immobilization on microtiter plates; however, the identity of the ligand on immobilized proteins remains unknown. We tested the hypotheses that immobilization of proteins generated an amyloid-like structure and that amyloid-like structure was the ligand for structurally altered pentameric CRP. We found that the Abs to amyloid-ß peptide 1-42 (Aß) reacted with immobilized proteins, indicating that some immobilized proteins express an Aß epitope. Accordingly, four different CRP mutants capable of binding to immobilized proteins were constructed, and their binding to fluid-phase Aß was determined. All CRP mutants bound to fluid-phase Aß, suggesting that Aß is a ligand for structurally altered pentameric CRP. In addition, the interaction between CRP mutants and Aß prevented the formation of Aß fibrils. The growth of Aß fibrils was also halted when CRP mutants were added to growing fibrils. Biochemical analyses of CRP mutants revealed altered topology of the Ca2+-binding site, suggesting a role of this region of CRP in binding to Aß. Combined with previous reports that structurally altered pentameric CRP is generated in vivo, we conclude that CRP is a dual pattern recognition molecule and an antiamyloidogenic protein. These findings have implications for Alzheimer's and other neurodegenerative diseases caused by amyloidosis and for the diseases caused by the deposition of otherwise fluid-phase proteins.

Functional Transformation of C-reactive Protein by Hydrogen Peroxide.

C-reactive protein (CRP) is present at sites of inflammation including amyloid plaques, atherosclerotic lesions, and arthritic joints. CRP, in its native pentameric structural conformation, binds to cells and molecules that have exposed phosphocholine (PCh) groups. CRP, in its non-native pentameric structural conformation, binds to a variety of deposited, denatured, and aggregated proteins, in addition to binding to PCh-containing substances. In this study, we investigated the effects of H2O2, a prototypical reactive oxygen species that is also present at sites of inflammation, on the ligand recognition function of CRP. Controlled H2O2 treatment of native CRP did not monomerize CRP and did not affect the PCh binding activity of CRP. In solid phase ELISA-based ligand binding assays, purified pentameric H2O2-treated CRP bound to a number of immobilized proteins including oxidized LDL, IgG, amyloid ß peptide 1-42, C4b-binding protein, and factor H, in a CRP concentration- and ligand concentration-dependent manner. Using oxidized LDL as a representative protein ligand for H2O2-treated CRP, we found that the binding occurred in a Ca2+-independent manner and did not involve the PCh-binding site of CRP. We conclude that H2O2 is a biological modifier of the structure and ligand recognition function of CRP. Overall, the data suggest that the ligand recognition function of CRP is dependent on the presence of an inflammatory microenvironment. We hypothesize that one of the functions of CRP at sites of inflammation is to sense the inflammatory microenvironment, change its own structure in response but remain pentameric, and then bind to pathogenic proteins deposited at those sites.

C-reactive protein protects mice against pneumococcal infection via both phosphocholine-dependent and phosphocholine-independent mechanisms.

The mechanism of action of C-reactive protein (CRP) in protecting mice against lethal Streptococcus pneumoniae infection is unknown. The involvement of the phosphocholine (PCh)-binding property of CRP in its antipneumococcal function previously has been explored twice, with conflicting results. In this study, using three different intravenous sepsis mouse models, we investigated the role of the PCh-binding property of CRP by employing a CRP mutant incapable of binding to PCh. The ability of wild-type CRP to protect mice against infection was found to differ in the three models; the protective ability of wild-type CRP decreased when the severity of infection was increased, as determined by measuring mortality and bacteremia. In the first animal model, in which we used 25 µg of CRP and 10(7) CFU of pneumococci, both wild-type and mutant CRP protected mice against infection, suggesting that the protection was independent of the PCh-binding activity of CRP. In the second model, in which we used 25 µg of CRP and 5 × 10(7) CFU of pneumococci, mutant CRP was not protective while wild-type CRP was, suggesting that the protection was dependent on the PCh-binding activity of CRP. In the third model, in which we used 150 µg of CRP and 10(7) CFU of pneumococci, mutant CRP was as protective as wild-type CRP, again indicating that the protection was independent of the PCh-binding activity of CRP. We conclude that both PCh-dependent and PCh-independent mechanisms are involved in the CRP-mediated decrease in bacteremia and the resulting protection of mice against pneumococcal infection.

Pattern of Drug Use and Associated Behaviors Among Female Injecting Drug Users From Northeast India: A Multi-Centric, Cross-Sectional, Comparative Study.

BACKGROUND: Studies from developed countries document the presence of injecting drug use among females and significantly higher vulnerabilities and risks as compared with male injecting drug users (IDUs). Studies comparing vulnerabilities and drug use patterns between female and male IDUs are not available for developing countries. OBJECTIVES: The aim of the study was to assess the drug use pattern and related HIV vulnerabilities among female IDUs and compare these findings with those from male IDUs from four states of Northeast India. METHOD: The study used data collected as part of a nationwide study of drug use pattern and related HIV vulnerabilities among IDUs. Ninety-eight female and 202 male IDUs accessing services from harm reduction sites across the four states of Northeast region of India were chosen through random sampling methodology. Drug use pattern, injecting practices, and knowledge of HIV were assessed using a structured questionnaire. RESULTS: Significantly higher proportion of female IDUs was uneducated, unemployed, reported their occupation as sex workers, and switched to injecting drug use faster as compared with male IDUs. Female IDUs practicing sex work differed significantly from those who did not with respect to frequency of daily injections, choice of drugs injected, and concomitant use of non-injecting drugs. More than half of female IDUs initiated sharing within the first month of injecting. CONCLUSIONS: The study demonstrates that female IDUs differ from male IDUs in their drug use pattern, initiation into injection as well as injecting behavior, which would be an important consideration during designing of female-specific interventions.

Recognition functions of pentameric C-reactive protein in cardiovascular disease.

C-reactive protein (CRP) performs two recognition functions that are relevant to cardiovascular disease. First, in its native pentameric conformation, CRP recognizes molecules and cells with exposed phosphocholine (PCh) groups, such as microbial pathogens and damaged cells. PCh-containing ligand-bound CRP activates the complement system to destroy the ligand. Thus, the PCh-binding function of CRP is defensive if it occurs on foreign pathogens because it results in the killing of the pathogen via complement activation. On the other hand, the PCh-binding function of CRP is detrimental if it occurs on injured host cells because it causes more damage to the tissue via complement activation; this is how CRP worsens acute myocardial infarction and ischemia/reperfusion injury. Second, in its nonnative pentameric conformation, CRP also recognizes atherogenic low-density lipoprotein (LDL). Recent data suggest that the LDL-binding function of CRP is beneficial because it prevents formation of macrophage foam cells, attenuates inflammatory effects of LDL, inhibits LDL oxidation, and reduces proatherogenic effects of macrophages, raising the possibility that nonnative CRP may show atheroprotective effects in experimental animals. In conclusion, temporarily inhibiting the PCh-binding function of CRP along with facilitating localized presence of nonnative pentameric CRP could be a promising approach to treat atherosclerosis and myocardial infarction. There is no need to stop the biosynthesis of CRP.

Serum Osteopontin as a Potential Marker for Metastasis and Prognosis in Primary Osteogenic Sarcoma: A Systematic Review.

Osteosarcoma (OS), a primary malignant bone tumor, poses significant challenges in diagnosis and prognosis. It is a painful medical burden, and treating it is still a difficult issue. Osteopontin (OPN), a multifunctional extracellular matrix protein, has emerged as a promising biomarker in this context. This systematic review explores the role of OPN as a diagnostic and prognostic marker in OS, highlighting its potential in enhancing early detection, monitoring disease progression, and predicting patient outcomes. Various studies have demonstrated elevated levels of OPN in OS patients, correlating with tumor aggressiveness, metastatic potential, and poor prognosis. In addition, OPN's involvement in tumor microenvironment regulation and metastatic processes underscores its clinical relevance as a biomarker. For this systematic review, comprehensive literature searches were conducted in the PubMed databases for research published between the database's establishment and November 11, 2022. Out of the nine studies that were available for analysis, a higher level of OPN in primary osteogenic sarcoma patients indicates a poorer prognosis and higher incidence of metastasis. OS has not shown commensurable progress with concerns to treatment approches and survical outcomes. However, the discovery of a biological marker that can predict metastasis and severity will be a groundbreaking development for advancements in OS diagnosis and treatment. Therefore, understanding the intricate interplay between OPN and OS pathogenesis holds promise for improving patient management and developing targeted therapeutic strategies.

Forecasting of Indian tourism industry using modeling approach.

Currently, India has become one of the largest economies of the world in which tourism and hospitality have significantly contributed; however, the growth rate of tourism industry has been greatly affected during the COVID-19 pandemic. In this study, we have used the modeling approach to analyze and understand the growth pattern of Indian tourism industry. To achieve this, we consider the data of international tourist arrivals before and after the lockdown. The Dickey-Fuller test, AIC and BIC methods are used to obtain the best fitted model and further, the accuracy of obtained model is also analyzed. Data and forecasting indicate that the weather and public holidays significantly affect the tourism industry.

A Comparison of the Clinicoradiological Outcomes of Intertrochanteric Fractures Treated Using Proximal Femoral Nail and Proximal Femoral Nail Anti-rotation.

Background Managing intertrochanteric fractures presents challenges for orthopedic surgeons, not only in fixing the fracture but also in preventing and managing associated complications, especially in the vulnerable geriatric population. Cephalomedullary nails are commonly used for surgical fixation due to their favorable functional profile, which preserves the hip's abductor lever arm and proximal femur anatomy. However, there's a lack of data comparing two major options: proximal femoral nail (PFN) and proximal femoral nail anti-rotation (PFNA). This study aimed to compare the radiological fracture reduction and fixation as well as functional outcomes of these two implants in treating intertrochanteric fractures. Methods The study, spanning 24 months, involved a prospective comparative design. Participants included patients diagnosed with intertrochanteric femur fractures classified as AO Type 31 A1, AO Type 31 A2, and AO Type 31 A3. Fifty patients were evenly distributed into PFN and PFNA groups. Preoperatively, clinical and radiological assessments were conducted, along with serum vitamin D level measurements. Surgeries, performed under anesthesia with image intensifier guidance, followed defined reduction and implant insertion protocols for each group. Postoperatively, evaluations were conducted up to six months, examining parameters such as tip-apex distance (TAD), Cleveland index, and modified Harris hip score, while documenting intraoperative duration and blood loss. Data analysis utilized the statistical software Statistical Package for Social Sciences (SPSS), version 22.0 (IBM Corp., Armonk, NY), employing descriptive statistics, chi-square tests, independent t-tests, and paired t-tests, with significance set at p < 0.05. Results In our study, 50 patients were enrolled, with equal gender distribution (64.0% male, 36.0% female, p=1.000). The mean ages in the PFN and PFNA groups were 66.2 ± 9.8 years and 66.4 ± 11.3 years, respectively (p=0.936). All fractures united by six months, with no implant-related complications reported. PFNA showed significantly lower blood loss and shorter surgery durations (p<0.001). TAD and neck shaft angle were similar between groups (p=0.826, p=0.555). Cleveland index placement and modified Harris hip score improvement were comparable (p=0.836, p<0.001). Predominant vitamin D deficiency was observed in both groups. Conclusion PFNA offers measurable intraoperative benefits over conventional PFN in terms of operative time, blood loss, and need for fluoroscopic imaging. However, no statistically observable benefits were noted in postoperative functional outcomes or complications between the two implants.

C-reactive protein lowers the serum level of IL-17, but not TNF-α, and decreases the incidence of collagen-induced arthritis in mice.

The biosynthesis of C-reactive protein (CRP) in the liver is increased in inflammatory diseases including rheumatoid arthritis. Previously published data suggest a protective function of CRP in arthritis; however, the mechanism of action of CRP remains undefined. The aim of this study was to evaluate the effects of human CRP on the development of collagen-induced arthritis (CIA) in mice which is an animal model of autoimmune inflammatory arthritis. Two CRP species were employed: wild-type CRP which binds to aggregated IgG at acidic pH and a CRP mutant which binds to aggregated IgG at physiological pH. Ten CRP injections were given on alternate days during the development of CIA. Both wild-type and mutant CRP reduced the incidence of CIA, that is, reduced the number of mice developing CIA; however, CRP did not affect the severity of the disease in arthritic mice. The serum levels of IL-17, IL-6, TNF-α, IL-10, IL-2 and IL-1ß were measured: both wild-type and mutant CRP decreased the level of IL-17 and IL-6 but not of TNF-α, IL-10, IL-2 and IL-1ß. These data suggest that CRP recognizes and binds to immune complexes, although it was not clear whether CRP functioned in its native pentameric or in its structurally altered pentameric form in the CIA model. Consequently, ligand-complexed CRP, through an as-yet undefined mechanism, directly or indirectly, inhibits the production of IL-17 and eventually protects against the initiation of the development of arthritis. The data also suggest that IL-17, not TNF-α, is critical for the development of autoimmune inflammatory arthritis.

Experience of patients on methadone maintenance treatment receiving take-home methadone doses during COVID-19 pandemic: A multi-site study from India.

BACKGROUND: Methadone take-home doses for opioid dependence treatment are strictly regulated due to diversion and overdose concerns, so patients must visit the clinic daily for dispensing. This was also done in India until the COVID-19 pandemic, when lockdown restriction compelled take- home dispensing of methadone. This study examined experience of patients who received take- home methadone during COVID-19 pandemic in India. METHODS: Observational, cross-sectional design. We contacted all consenting methadone centres in India during the lockdown and selected those that provided take-home doses for the study. Patients who received daily methadone before the lockdown and take-home doses after were interviewed using a study-specific questionnaire. RESULTS: The study had 210 participants. Take-home methadone was dispensed for 2.5 days on average in each dispensing. When taking methadone at home, 3.3% split their dose 25% took less than the prescribed dose to save it for a rainy days, and 3.3% reported an overdose episode. Adherence improved in 58.6% participants after take-home methadone. Participants perceived many benefits from take-home methadone such as reduced hospital visits and travel time to collect methadone, improvement in work, and financial savings. About 54.3% participants reported storing their take-home doses safely, and 1.9% reported that their family consumed methadone by mistake. CONCLUSIONS: Take-home methadone was found to be beneficial to most participants in terms of time saved and improved productivity. Preconceived concerns of providing take-home methadone in terms of its overdose, diversion, or accidental ingestion by others are not commonly seen when individuals are provided take-home doses of methadone.

The phosphocholine-binding pocket on C-reactive protein is necessary for initial protection of mice against pneumococcal infection.

Human C-reactive protein (CRP) protects mice from lethal Streptococcus pneumoniae infection when injected into mice within the range of 6 h before to 2 h after the administration of pneumococci. Because CRP binds to phosphocholine-containing substances and subsequently activates the complement system, it has been proposed that the antipneumococcal function of CRP requires the binding of CRP to phosphocholine moieties present in pneumococcal cell wall C-polysaccharide. To test this proposal experimentally, in this study, we utilized a new CRP mutant incapable of binding to phosphocholine. Based on the structure of CRP-phosphocholine complexes, which showed that Phe(66), Thr(76), and Glu(81) formed the phosphocholine-binding pocket, we constructed a CRP mutant F66A/T76Y/E81A in which the pocket was blocked by substituting Tyr for Thr(76). When compared with wild-type CRP, mutant CRP bound more avidly to phosphoethanolamine and could be purified by affinity chromatography using phosphoethanolamine-conjugated Sepharose. Mutant CRP did not bind to phosphocholine, C-polysaccharide, or pneumococci. Mutant CRP was free in the mouse serum, and its rate of clearance in vivo was not faster than that of wild-type CRP. When either 25 µg or 150 µg of CRP was administered into mice, unlike wild-type CRP, mutant CRP did not protect mice from lethal pneumococcal infection. Mice injected with mutant CRP had higher mortality rates than mice that received wild-type CRP. Decreased survival was due to the increased bacteremia in mice treated with mutant CRP. We conclude that the phosphocholine-binding pocket on CRP is necessary for CRP-mediated initial protection of mice against lethal pneumococcal infection.

Exposing a hidden functional site of C-reactive protein by site-directed mutagenesis.

C-reactive protein (CRP) is a cyclic pentameric protein whose major binding specificity, at physiological pH, is for substances bearing exposed phosphocholine moieties. Another pentameric form of CRP, which exists at acidic pH, displays binding activity for oxidized LDL (ox-LDL). The ox-LDL-binding site in CRP, which is hidden at physiological pH, is exposed by acidic pH-induced structural changes in pentameric CRP. The aim of this study was to expose the hidden ox-LDL-binding site of CRP by site-directed mutagenesis and to generate a CRP mutant that can bind to ox-LDL without the requirement of acidic pH. Mutation of Glu(42), an amino acid that participates in intersubunit interactions in the CRP pentamer and is buried, to Gln resulted in a CRP mutant (E42Q) that showed significant binding activity for ox-LDL at physiological pH. For maximal binding to ox-LDL, E42Q CRP required a pH much less acidic than that required by wild-type CRP. At any given pH, E42Q CRP was more efficient than wild-type CRP in binding to ox-LDL. Like wild-type CRP, E42Q CRP remained pentameric at acidic pH. Also, E42Q CRP was more efficient than wild-type CRP in binding to several other deposited, conformationally altered proteins. The E42Q CRP mutant provides a tool to investigate the functions of CRP in defined animal models of inflammatory diseases including atherosclerosis because wild-type CRP requires acidic pH to bind to deposited, conformationally altered proteins, including ox-LDL, and available animal models may not have sufficient acidosis or other possible modifiers of the pentameric structure of CRP at the sites of inflammation.

Epidemiology of Osteoporosis.

Background: India has a population capacity of 1.2 billion people. With a worldwide aging population, the prevention and management of osteoporosis has become a significant healthcare challenge. It is crucial to recognize the factors impacting poor bone health and appreciate the many hurdles to treat the disease to provide a better quality of life and decrease the financial burden on healthcare. Purpose: In this review article, we discuss the epidemiology of osteoporosis and address the definition, incidence, and prevalence, geographical variation in the occurrence of osteoporosis, and the risk factors for osteoporosis. Methods: Search terms using various combinations of the keywords 'osteoporosis,' 'epidemiology,' 'incidence,' 'prevalence,' 'fracture,' 'India,' 'world,' 'screening,' and 'FRAX' was done to review all relevant literature till June 2023. Results & Conclusion: India has a recent estimate of population capacity of 1.2 billion people. Various studies have revealed an osteoporosis prevalence in Indian women ranging from 8% to 62%. Poor dietary calcium intake, low vitamin D, and lifestyle changes contribute to osteoporosis.

Short-term Follow-up of Autologous Adult Live-Cultured Osteoblasts Implantation in Avascular Necrosis of Femoral Head Secondary to Sickle Cell Anemia-Case Series.

Introduction: The prevalence of avascular necrosis (AVN) of the femoral head in sickle cell anemia is 50% whereas untreated cases lead to total hip replacement. The recent development in cellular therapy paves the way to utilize autologous adult live-cultured osteoblasts (AALCO) in the management of AVN of the femoral head secondary to sickle cell anemia. Case Report: We performed AALCO implantation in sickle cell anemia cases with AVN of the femoral head and were followed up for 6 months with the regular recording of visual analog score and modified Harris Hip Score. Conclusion: AALCO implantation for the management of AVN of the femoral head due to sickle cell anemia appears to be the biological management of choice as it results in pain reduction and improvement in function.

Total Hip Arthroplasty in Neglected Acetabular Fracture with Pipkin Type 4 Femoral Head Fracture. A Case Report.

Introduction: Pipkin type 4 fracture is defined as hip dislocation with femoral head fracture and concomitant acetabular rim fracture. These fractures are rare. Neglected fractures develop adaptive changes in the acetabulum, femoral head, and soft tissues around the hip joint, leading to hip arthritis. Total hip arthroplasty is preferred in such cases. After an extensive literature review, we did not find any guidelines for managing neglected Pipkin type 4 fractures. Case Report: A 47-year-old male presented with pain in his left hip and an inability to bear weight on his left lower limb. He had a road traffic accident 1 year ago. On clinical examination, there was a shortening of 3 cm and reduced hip range of motion on 3D computed tomography posterosuperior defect of the acetabular wall along with Pipkin type 4 femoral head fracture was detected. Total hip arthroplasty with acetabular reconstruction using a femoral head autograft was done. At 1 year of follow-up, the patient was pain-free and could walk without any assistance with a normal gait. Conclusion: Uncemented total hip arthroplasty with an autologous structural femoral head graft is a suitable method of treatment for neglected Pipkin type 4 fractures. It preserves bone stock and does not add any financial burden.

IL-6 regulates induction of C-reactive protein gene expression by activating STAT3 isoforms.

C-reactive protein (CRP) is synthesized in hepatocytes. The serum concentration of CRP increases dramatically during the acute phase response. In human hepatoma Hep3B cells, maximal CRP expression occurs in cells treated with the combination of IL-6 and IL-1ß. IL-6 induces transcription of the CRP gene and IL-1ß synergistically enhances the effects of IL-6. We investigated the role of IL-6-activated transcription factor STAT3, also known as STAT3α, in inducing CRP expression since we identified four consensus STAT3-binding sites centered at positions - 72, - 108, - 134 and - 164 on the CRP promoter. It has been shown previously that STAT3 binds to the site at - 108 and induces CRP expression. We found that STAT3 also bound to the other three sites, and several STAT3-containing complexes were formed at each site, suggesting the presence of STAT3 isoforms and additional transcription factors in the complexes. Mutation of the STAT3 sites at - 108, - 134 or - 164 resulted in decreased CRP expression in response to IL-6 and IL-1ß treatment, although the synergy between IL-6 and IL-1ß was not affected by the mutations. The STAT3 site at - 72 could not be investigated employing mutagenesis. We also found that IL-6 activated two isoforms of STAT3 in Hep3B cells: STAT3α which contains both a DNA-binding domain and a transactivation domain and STAT3ß which contains only the DNA-binding domain. Taken together, these findings raise the possibility that IL-6 not only induces CRP expression but also regulates the induction of CRP expression by activating STAT3 isoforms and by utilizing all four STAT3 sites.

Congenital Elbow Dislocation: A Case Report.

CASE: We present a case of a 12-day-old male baby who presented with right elbow deformity and inability to flex the elbow. Radiographs and computed tomography scan of the elbow revealed loss of humeroulnar alignment, superior migration of olecranon, and posteromedial displacement, suggesting an elbow dislocation. The child was successfully managed with open reduction and Kirschner wire fixation of the elbow joint. At 1-year follow-up, the child has a well-reduced and stable elbow joint with a functional range of movements. CONCLUSION: Congenital dislocation of the ulnohumeral joint can occur because of hypoplasia of the skeletal components or tissue interposition within the joint articulation.

Plasma Interleukin-33 Cannot Predict Hip Osteonecrosis in Patients With Sickle Cell Disease: A Case-Control Study.

Background Plasma interleukin-33 (IL-33), a cytokine associated with inflammatory and autoimmune disease, has been described to be significantly raised in osteonecrosis of the femoral head (ONFH) and hence was recommended for use as a marker for ONFH. The concentration of plasma interleukin-33 level has not been estimated in any studies conducted in patients with sickle cell disease (SCD); hence, we investigated the levels of plasma interleukin-33 in patients with sickle cell disease with or without ONFH to assess whether it can be used as a marker for the early detection of ONFH in this disease also. Methods Forty-four consecutive patients with sickle cell disease with osteonecrosis of the femoral head and matched controls without ONFH were evaluated for plasma interleukin-33 levels by enzyme-linked immunosorbent assay (ELISA). All patients were confirmed for sickle cell disease using high-performance liquid chromatography (HPLC). ONFH was diagnosed in patients with sickle cell disease using clinical-radiological findings. Univariate and multivariate analyses were performed using the IL-33 level as the dependent variable. Results Plasma IL-33 levels were comparable in 44 patients with sickle cell disease with osteonecrosis of the femoral head as compared with 24 patients with sickle cell disease without ONFH (2.05 ± 4.57 pg/mL versus 1.50 ± 2.89 pg/mL, p-value = 0.590). There was no significant difference in IL-33 levels in different stages of avascular necrosis (AVN). Conclusions Plasma interleukin-33 levels cannot act as a marker of ONFH as were being considered in idiopathic ONFH or ONFH caused by other causes such as trauma and chronic steroid or alcohol usage.

Pathological Fractures of Bilateral Neck of Femur in Geriatric Population: Our Experience and Review of Literature.

Introduction: Bilateral neck of femur stress fractures is rare clinical presentation in elderly population. Diagnosis of such fractures when presented can be difficult with inconclusive radiographs and hence their early diagnosis by high index of suspicion and their management can avoid further complications in this age group. In this case series, we report three elderly patients with different predisposing factors for their fractures and treatment options chosen with detailed discussion about the management. Case Report: These case series of three elderly patients with bilateral neck of femur fracture were associated with different predisposing factors. Grave's disease or primary thyrotoxicosis, steroid induced osteoporosis, and renal osteodystrophy were the identified risk factors in these patients. Biochemical evaluation for osteoporosis in these patients revealed significant derangement in levels of vitamin D, Alkaline phosphatase, and serum calcium. One of these patients was operated with hemiarthroplasty and osteosynthesis with percutaneous screw fixation on the other side. Management of osteoporosis, dietary modifications, and lifestyle changes in these patients also had significant impact on their prognosis. Conclusion: Stress fractures occurring in elderly individuals with simultaneous bilateral presentation are rare and can be prevented if taken care on their risk factors. As radiographs remain inconclusive few times in these kinds of fracture, a high degree of suspicion is to be kept in mind. With advanced diagnostic tools and surgeries, they carry good prognosis if timely intervention is provided.

Identification of acidic pH-dependent ligands of pentameric C-reactive protein.

C-reactive protein (CRP) is a phylogenetically conserved protein; in humans, it is present in the plasma and at sites of inflammation. At physiological pH, native pentameric CRP exhibits calcium-dependent binding specificity for phosphocholine. In this study, we determined the binding specificities of CRP at acidic pH, a characteristic of inflammatory sites. We investigated the binding of fluid-phase CRP to six immobilized proteins: complement factor H, oxidized low-density lipoprotein, complement C3b, IgG, amyloid ß, and BSA immobilized on microtiter plates. At pH 7.0, CRP did not bind to any of these proteins, but, at pH ranging from 5.2 to 4.6, CRP bound to all six proteins. Acidic pH did not monomerize CRP but modified the pentameric structure, as determined by gel filtration, 1-anilinonaphthalene-8-sulfonic acid-binding fluorescence, and phosphocholine-binding assays. Some modifications in CRP were reversible at pH 7.0, for example, the phosphocholine-binding activity of CRP, which was reduced at acidic pH, was restored after pH neutralization. For efficient binding of acidic pH-treated CRP to immobilized proteins, it was necessary that the immobilized proteins, except factor H, were also exposed to acidic pH. Because immobilization of proteins on microtiter plates and exposure of immobilized proteins to acidic pH alter the conformation of immobilized proteins, our findings suggest that conformationally altered proteins form a CRP-ligand in acidic environment, regardless of the identity of the protein. This ligand binding specificity of CRP in its acidic pH-induced pentameric state has implications for toxic conditions involving protein misfolding in acidic environments and favors the conservation of CRP throughout evolution.