Physician Health in the Times of COVID-19.

BACKGROUND AND OBJECTIVES: A virtual registry study evaluating real world evidence on physicians' use of prophylactic regimens for protection against SARS-CoV-2. This paper summarizes the interim results. METHODS: Asymptomatic physicians at risk of acquiring SARS-CoV-2 responded to online questions at baseline and 7 weeks post-baseline. Baseline data included demographics, prophylaxis regimen (including "no prophylaxis") and start date. Participants who provided complete week-7 data (information on type of health facility [COVID/Non-COVID], number of presumed/confirmed cases exposed to, PPE use, SARS-CoV-2 testing and symptoms, regimen adherence and intercurrent illness) comprised the Completer population. Limited data (regimen adherence, SARS-CoV-2 testing) was collected for participants who failed to provide complete week7 data. Those providing limited/complete information comprised the Evaluable population. RESULTS: Of 369 enrolled participants, 182 (mean age 42±11.05 years) comprised the Evaluable population. They showed a male preponderance (67.6%). Practitioners from Maharashtra (59.9%) and specialties of Pediatrics, Internal Medicine, Anesthesiology and Critical Care (63.2%) accounted for the majority. ICMR's HCQ prophylaxis regimen was initiated by 125 (68.7%) participants with 31 (17%) initiating 'No prophylaxis'. The highest adherence was for the ICMRregimen (87.2%). In the Completer population comprising 150 participants, 87 were exposed to presumed (81) and/or confirmed cases (60). Most exposures to confirmed cases (49, 81.7%) were high-risk. PPE use was generally high (75-100%). Most participants (94.7%) did not report an AE. The proportions with an AE was similar with ICMR regimen (5.9%) and no prophylaxis (6.5%). INTERPRETATION AND CONCLUSIONS: Physicians in India preferred ICMR's HCQ regimen. The regimen appears to be safe and associated with a high level of adherence.

Expert Group Consensus Opinion: Role of Anti-inflammatory Agents in the Management of Type-2 Diabetes (T2D).

Diabetes is a major public health emergency of the 21st century. Results of the Indian Council of Medical Research-INdia DIABetes (ICMR-INDIAB) study have found prevalence of diabetes and prediabetes in India to be as high as 7.3% and 10.3%, respectively with nation-wide projection of 77.2 million people with prediabetes and 69.2 million with diabetes. It is well established that insulin resistance (IR) and islet ß-cell failure are the two major features of T2D Multiple mechanisms including glucotoxicity, lipotoxicity, oxidative stress, endoplasmic reticulum stress, formation of amyloid deposits in the islets, etc. have been hypothesized to participate in the pathology of the disease. In the concluding decade of the last century, numerous studies - prospective and cross-sectional, have confirmed the role of chronic low-grade inflammation as a pathogenetic factor of T2D. It has been shown that increased levels of various inflammatory markers and mediators including fundamental markers like white blood cell count, C-reactive protein (CRP) to the more specific circulating cytokines like, interleukin-6 (IL-6), IL-1ß, plasminogen activator inhibitor-1 (PAI-1), etc. correlate with incident T2D. Based on the robust evidence implying the role of inflammation in T2D pathogenesis, several studies have proven that the proinflammatory cytokines play a central role in the development of microvascular diabetic complications such as nephropathy, retinopathy, and neuropathy. Inflammation in T2D causes accelerated atherosclerosis which predisposes to CVD, the leading cause of mortality in these patients. Recently there is a considerable increase in the interest among the researchers about anti-inflammatory therapies in the setting of chronic disorders such as T2D and CV diseases. In a multi-country study conducted in Asia, approximately 50% of Indian respondents had poor diabetes control. Most patients initially respond to sulfonylurea and/or metformin, and later these agents lose their effectiveness with time. Therapeutic option in patients uncontrolled on two-drug combination therapy is either to add third oral drug or insulin. However, use of insulin is limited due to its high cost and poor compliance. Majority of new treatment options like GLP1 agonists, insulin analogs and SGLT2 inhibitors are costly considering they are still under patent. The thiazolidinedione class of drugs is associated with adverse effects like fluid retention and weight gain that may result in or exacerbate edema and congestive heart failure. Thus there is a need for a safe and inexpensive treatment option for the management of uncontrolled T2D. Considering the role of inflammation in T2D pathogenesis, the drug should not only have antihyperglycemic effects but also reduce inflammatory burden thus reducing the progression and complications of T2D. The current interest is apparently directed towards drugs targeting inflammation acting at different stages of the inflammatory cascade. In the recently published CANTOS study, canakinumab, a selective, high-affinity, fully human monoclonal antibody which inhibits IL-1ß, has no consistent long-term benefits on HbA1c. Other selective inhibitors like anakinra (IL-1 receptor antagonist) and etanercept (TNF inhibitor) too have yielded modest effects on glycemic parameters and insulin sensitivity. However, hydroxychloroquine (HCQ), a broad anti-inflammatory agent has been shown to reduce HbA1c by 0.87%. Hydroxychloroquine (HCQ) is considered as one of the safest disease modifying anti-rheumatic drug, used widely for the treatment of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). The effect of HCQ in preventing development of diabetes in patients with chronic inflammatory diseases was highlighted in a prospective observational study of 4905 adults with rheumatoid arthritis and no diabetes with 21.5 years of follow-up. Patients who took HCQ for more than 4 years had a significant 77% lower risk of diabetes compared with non users of HCQ (RR, 0.23; 95% CI, 0.11-0.50). Taking cue from this study highlighting the anti-diabetic effect of HCQ, pioneering research studies evaluating these effects of HCQ were conducted in India. In 2014, hydroxychloroquine 400 mg got DCGI approval as an adjunct to diet and exercise to improve glycemic control of patients on metformin, sulfonylurea combination in Type 2 diabetes.

Rare disease heralded by pulmonary manifestations: Avoiding pitfalls of an "asthma" label.

Pulmonary manifestations are seldom recognized as symptoms of storage disorders. The report describes the diagnostic journey in a 30-month-old male infant, born of a third-degree consanguineous marriage referred to our institute as severe persistent asthma. History revealed that the child had progressively worsening breathlessness and persistent dry cough not associated with fever but accompanied by weight loss. On physical examination, there was growth failure, respiratory distress, clubbing, hepatosplenomegaly, and occasional rhonchi. Blood gas revealed hypoxemia which improved with oxygen administration. Plain X-rays and high-resolution computed tomography of the chest showed perihilar alveolar infiltrates and patchy consolidation. The clinicoradiological features did not support a diagnosis of asthma but favored interstitial lung disease (ILD). Bronchoalveolar lavage was performed as a first-tier investigation. It showed periodic acid-Schiff-negative foamy macrophages. The clues of consanguinity, visceromegaly, ILD, and foamy macrophages in the bronchoalveolar fluid prompted consideration of lysosomal storage disorders as the likely etiology. Gaucher disease and Niemann-Pick disease A/B were ruled out by enzyme estimation. Niemann-Pick disease type C was suspected and confirmed by detecting a homozygous mutation in the NPC2 gene. This case serves to caution physicians against labeling breathlessness in every toddler as asthma. It emphasizes the importance of searching for tell-tale signs such as clubbing and extrapulmonary clues which point to a systemic disease such as lysosomal storage disorders as a primary etiology of chronic respiratory symptoms.

When potion becomes poison! A case report of flecainide toxicity.

We report a 48-day-old female infant, who developed cardiac conduction abnormalities and seizures secondary to supratherapeutic doses of oral flecainide. Flecainide was started in this infant for treatment of supraventricular tachycardia. The drug was withdrawn with successful normalization of the QRS complex and no further recurrence of seizures. The Naranjo probability score for adverse drug reaction was 8, making the causality "probable." The case restates an important message that physicians should be aware of the side effects of the drugs that they prescribe, especially of those drugs which have a narrow therapeutic window.

"FISHed" out the diagnosis: A case of DiGeorge syndrome.

Our patient presented with congenital heart disease (CHD: Tetralogy of Fallot), hypocalcemia, hypoparathyroidism, and facial dysmorphisms. Suspecting DiGeorge syndrome (DGS), a fluorescence in situ hybridization (FISH) analysis for 22q11.2 deletion was made. The child had a hemizygous deletion in the 22q11.2 region, diagnostic of DGS. Unfortunately, the patient succumbed to the heart disease. DGS is the most common microdeletion syndrome, and probably underrecognized due to the varied manifestations. This case stresses the importance of a detailed physical examination and a high index of suspicion for diagnosing this genetic condition. Timely diagnosis can help manage and monitor these patients better and also offer prenatal diagnosis in the next pregnancy.

Platelets contain tissue factor pathway inhibitor-2 derived from megakaryocytes and inhibits fibrinolysis.

Tissue factor pathway inhibitor-2 (TFPI-2) is a homologue of TFPI-1 and contains three Kunitz-type domains and a basic C terminus region. The N-terminal domain of TFPI-2 is the only inhibitory domain, and it inhibits plasma kallikrein, factor XIa, and plasmin. However, plasma TFPI-2 levels are negligible (≤20 pM) in the context of influencing clotting or fibrinolysis. Here, we report that platelets contain significant amounts of TFPI-2 derived from megakaryocytes. We employed RT-PCR, Western blotting, immunohistochemistry, and confocal microscopy to determine that platelets, MEG-01 megakaryoblastic cells, and bone marrow megakaryocytes contain TFPI-2. ELISA data reveal that TFPI-2 binds factor V (FV) and partially B-domain-deleted FV (FV-1033) with K(d) ~9 nM and binds FVa with K(d) ~100 nM. Steady state analysis of surface plasmon resonance data reveal that TFPI-2 and TFPI-1 bind FV-1033 with K(d) ~36-48 nM and bind FVa with K(d) ~252-456 nM. Further, TFPI-1 (but not TFPI-1161) competes with TFPI-2 in binding to FV. These data indicate that the C-terminal basic region of TFPI-2 is similar to that of TFPI-1 and plays a role in binding to the FV B-domain acidic region. Using pull-down assays and Western blots, we show that TFPI-2 is associated with platelet FV/FVa. TFPI-2 (~7 nM) in plasma of women at the onset of labor is also, in part, associated with FV. Importantly, TFPI-2 in platelets and in plasma of pregnant women inhibits FXIa and tissue-type plasminogen activator-induced clot fibrinolysis. In conclusion, TFPI-2 in platelets from normal or pregnant subjects and in plasma from pregnant women binds FV/Va and regulates intrinsic coagulation and fibrinolysis.

Quantifying vitamin K-dependent holoprotein compaction caused by differential γ-carboxylation using high-pressure size exclusion chromatography.

This study uses high-pressure size exclusion chromatography (HPSEC) to quantify divalent metal ion (X(2+))-induced compaction found in vitamin K-dependent (VKD) proteins. Multiple X(2+) binding sites formed by the presence of up to 12 γ-carboxyglutamic acid (Gla) residues are present in plasma-derived FIX (pd-FIX) and recombinant FIX (r-FIX). Analytical ultracentrifugation (AUC) was used to calibrate the Stokes radius (R) measured by HPSEC. A compaction of pd-FIX caused by the filling of Ca(2+) and Mg(2+) binding sites resulted in a 5 to 6% decrease in radius of hydration as observed by HPSEC. The filling of Ca(2+) sites resulted in greater compaction than for Mg(2+) alone where this effect was additive or greater when both ions were present at physiological levels. Less X(2+)-induced compaction was observed in r-FIX with lower Gla content populations, which enabled the separation of biologically active r-FIX species from inactive ones by HPSEC. HPSEC was sensitive to R changes of approximately 0.01nm that enabled the detection of FIX compaction that was likely cooperative in nature between lower avidity X(2+) sites of the Gla domain and higher avidity X(2+) sites of the epidermal growth factor 1 (EGF1)-like domain.

Decoy plasminogen receptor containing a selective Kunitz-inhibitory domain.

Kunitz domain 1 (KD1) of tissue factor pathway inhibitor-2 in which P2' residue Leu17 (bovine pancreatic trypsin inhibitor numbering) is mutated to Arg selectively inhibits the active site of plasmin with ∼5-fold improved affinity. Thrombin cleavage (24 h extended incubation at a 1:50 enzyme-to-substrate ratio) of the KD1 mutant (Leu17Arg) yielded a smaller molecule containing the intact Kunitz domain with no detectable change in the active-site inhibitory function. The N-terminal sequencing and MALDI-TOF/ESI data revealed that the starting molecule has a C-terminal valine (KD1L17R-VT), whereas the smaller molecule has a C-terminal lysine (KD1L17R-KT). Because KD1L17R-KT has C-terminal lysine, we examined whether it could serve as a decoy receptor for plasminogen/plasmin. Such a molecule might inhibit plasminogen activation as well as the active site of generated plasmin. In surface plasmon resonance experiments, tissue plasminogen activator (tPA) and Glu-plasminogen bound to KD1L17R-KT (Kd ∼ 0.2 to 0.3 µM) but not to KD1L17R-VT. Furthermore, KD1L17R-KT inhibited tPA-induced plasma clot fibrinolysis more efficiently than KD1L17R-VT. Additionally, compared to ε-aminocaproic acid KD1L17R-KT was more effective in reducing blood loss in a mouse liver-laceration injury model, where the fibrinolytic system is activated. In further experiments, the micro(µ)-plasmin-KD1L17R-KT complex inhibited urokinase-induced plasminogen activation on phorbol-12-myristate-13-acetate-stimulated U937 monocyte-like cells, whereas the µ-plasmin-KD1L17R-VT complex failed to inhibit this process. In conclusion, KD1L17R-KT inhibits the active site of plasmin as well as acts as a decoy receptor for the kringle domain(s) of plasminogen/plasmin; hence, it limits both plasmin generation and activity. With its dual function, KD1L17R-KT could serve as a preferred agent for controlling plasminogen activation in pathological processes.

A sequential mechanism for exosite-mediated factor IX activation by factor XIa.

During blood coagulation, the protease factor XIa (fXIa) activates factor IX (fIX). We describe a new mechanism for this process. FIX is cleaved initially after Arg(145) to form fIXα, and then after Arg(180) to form the protease fIXaß. FIXα is released from fXIa, and must rebind for cleavage after Arg(180) to occur. Catalytic efficiency of cleavage after Arg(180) is 7-fold greater than for cleavage after Arg(145), limiting fIXα accumulation. FXIa contains four apple domains (A1-A4) and a catalytic domain. Exosite(s) on fXIa are required for fIX binding, however, there is lack of consensus on their location(s), with sites on the A2, A3, and catalytic domains described. Replacing the A3 domain with the prekallikrein A3 domain increases K(m) for fIX cleavage after Arg(145) and Arg(180) 25- and ≥ 90-fold, respectively, and markedly decreases k(cat) for cleavage after Arg(180). Similar results were obtained with the isolated fXIa catalytic domain, or fXIa in the absence of Ca(2+). Forms of fXIa lacking the A3 domain exhibit 15-fold lower catalytic efficiency for cleavage after Arg(180) than for cleavage after Arg(145), resulting in fIXα accumulation. Replacing the A2 domain does not affect fIX activation. The results demonstrate that fXIa activates fIX by an exosite- and Ca(2+)-mediated release-rebind mechanism in which efficiency of the second cleavage is enhanced by conformational changes resulting from the first cleavage. Initial binding of fIX and fIXα requires an exosite on the fXIa A3 domain, but not the A2 or catalytic domain.

Trends of Diversity in Neuroradiology Trainees in United States 2015-2022.

Radiology has historically not been a very diverse field. Many steps have been taken in the past decade to increase diversity in the field and make it more inclusive. This study shows the relative trends specifically in neuroradiology trainees, and the need for reassessment and further steps to increase diversity.

Malpractice Litigation Related to Diagnosis and Treatment of Intracranial Aneurysms.

BACKGROUND AND PURPOSE: Approaches to management of intracranial aneurysms are inconsistent, in part due to apprehension relating to potential malpractice claims. The purpose of this article was to review the causes of action underlying medical malpractice lawsuits related to the diagnosis and management of intracranial aneurysms and to identify the factors associated and their outcomes. MATERIALS AND METHODS: We consulted 2 large legal databases in the United States to search for cases in which there were jury awards and settlements related to the diagnosis and management of patients with intracranial aneurysms in the United States. Files were screened to include only those cases in which the cause of action involved negligence in the diagnosis and management of a patient with an intracranial aneurysm. RESULTS: Between 2000 and 2020, two hundred eighty-seven published case summaries were identified, of which 133 were eligible for inclusion in the analysis. Radiologists constituted 16% of 159 physicians sued in these lawsuits. Failure to diagnose was the most common medical malpractice claim referenced (100/133 cases), with the most common subgroups being "failure to include cerebral aneurysm as a differential and thus perform adequate work-up" (30 cases), and "failure to correctly interpret aneurysm evidence on CT or MR imaging" (16 cases). Only 6 of these 16 cases were adjudicated at trial, with 2 decided in favor of the plaintiff (awarded $4,000,000 and $43,000,000, respectively). CONCLUSIONS: Incorrect interpretation of imaging is relatively infrequent as a cause of malpractice litigation compared with failure to diagnose aneurysms in the clinical setting by neurosurgeons, emergency physicians, and primary care providers.

Engineering kunitz domain 1 (KD1) of human tissue factor pathway inhibitor-2 to selectively inhibit fibrinolysis: properties of KD1-L17R variant.

Tissue factor pathway inhibitor-2 (TFPI-2) inhibits factor XIa, plasma kallikrein, and factor VIIa/tissue factor; accordingly, it has been proposed for use as an anticoagulant. Full-length TFPI-2 or its isolated first Kunitz domain (KD1) also inhibits plasmin; therefore, it has been proposed for use as an antifibrinolytic agent. However, the anticoagulant properties of TFPI-2 or KD1 would diminish its antifibrinolytic function. In this study, structure-based investigations and analysis of the serine protease profiles revealed that coagulation enzymes prefer a hydrophobic residue at the P2' position in their substrates/inhibitors, whereas plasmin prefers a positively charged arginine residue at the corresponding position in its substrates/inhibitors. Based upon this observation, we changed the P2' residue Leu-17 in KD1 to Arg (KD1-L17R) and compared its inhibitory properties with wild-type KD1 (KD1-WT). Both WT and KD1-L17R were expressed in Escherichia coli, folded, and purified to homogeneity. N-terminal sequences and mass spectra confirmed proper expression of KD1-WT and KD1-L17R. Compared with KD1-WT, the KD1-L17R did not inhibit factor XIa, plasma kallikrein, or factor VIIa/tissue factor. Furthermore, KD1-L17R inhibited plasmin with ∼6-fold increased affinity and effectively prevented plasma clot fibrinolysis induced by tissue plasminogen activator. Similarly, in a mouse liver laceration bleeding model, KD1-L17R was ∼8-fold more effective than KD1-WT in preventing blood loss. Importantly, in this bleeding model, KD1-L17R was equally or more effective than aprotinin or tranexamic acid, which have been used as antifibrinolytic agents to prevent blood loss during major surgery/trauma. Furthermore, as compared with aprotinin, renal toxicity was not observed with KD1-L17R.

Role of Placenta Accreta Index for Diagnosis of Placenta Accreta Spectrum in High-Risk Patients.

Background: Antenatal diagnosis of placenta accreta spectrum (PAS) can ensure multidisciplinary management at center of excellence which can reduce maternal and fetal complications. This can be established by a scoring system which provides a standardized criterion for the diagnosis and management. The objective of our study was to assess the placenta accreta index (PAI) and its individual parameters for diagnosis of PAS in high-risk patients. Methods: A prospective study was conducted on 71 pregnant women with placenta previa and previous cesarean section. After informed consent, history was taken and ultrasonography was used to calculate the PAI for each patient. Definitive diagnosis was made clinically during cesarean section or by histopathology for those requiring hysterectomy. The data were evaluated using the latest version of Statistical Package for the Social Sciences software. Results: All ultrasound parameters of placenta accreta index were statistically significant for predicting PAS (p value < 0.001). ROC curve with AUC of 0.87 95% CI of 0.77-0.94 showed that a score of 4.75 was the best cutoff value to diagnose PAS. Out of the 30 patients found to have placental invasion, 22 had a PAI score of more than 4.75. The score was found to have a sensitivity of 73.3%, specificity 95.1%, positive predictive value 91.7%, negative predictive value 83% and diagnostic accuracy 85.9%. Conclusions: Women with placenta previa and history of previous CS should undergo screening by PAI, and a cutoff value of ≥ 4.75 should be viewed with high index of suspicion for the presence of PAS.

Differential associations of conduct disorder, callous-unemotional traits and irritability with outcome expectations and values regarding the consequences of aggression.

BACKGROUND: Previous work has examined the association of aggression levels and callous-unemotional traits with outcome expectations and values regarding the consequences of aggression. Less work has examined the outcome expectations and values regarding the consequences of aggression of adolescents with Conduct Disorder (CD). Also, no studies have examined links between irritability (a second socio-affective trait associated with CD) and these social cognitive processes despite the core function of anger in retaliatory aggression and establishing dominance. METHOD: The current study, investigating these issues, involved 193 adolescents (typically developing [TD; N = 106], 87 cases with CD [N = 87]). Participants completed an adaptation of the Outcomes Expectations and Values Questionnaire and were assessed for CU traits and irritability via the Inventory of Callous-Unemotional traits and the Affective Reactivity Index. RESULTS: While CD was associated with atypical outcome expectations this was not seen within statistical models including CU traits and irritability. CU traits were associated with decreased expectation that aggression would result in feelings of remorse and victim suffering, as well as decreased concern that aggressive acts would result in punishment and victim suffering. Irritability was associated with increased expectations and concern that aggression would result in dominance and forced respect. CONCLUSIONS: The results suggest that CU traits and irritability, often present in youth with CD, are associated with different forms of maladaptive outcome expectations and values regarding the consequences of aggression. This suggests that the atypical social cognitive processes underlying aggressive behavior among youth exhibiting CU traits may differ from those exhibiting problems regulating anger.

Structure of human factor VIIa-soluble tissue factor with calcium, magnesium and rubidium.

Coagulation factor VIIa (FVIIa) consists of a γ-carboxyglutamic acid (GLA) domain, two epidermal growth factor-like (EGF) domains and a protease domain. FVIIa binds three Mg2+ ions and four Ca2+ ions in the GLA domain, one Ca2+ ion in the EGF1 domain and one Ca2+ ion in the protease domain. Further, FVIIa contains an Na+ site in the protease domain. Since Na+ and water share the same number of electrons, Na+ sites in proteins are difficult to distinguish from waters in X-ray structures. Here, to verify the Na+ site in FVIIa, the structure of the FVIIa-soluble tissue factor (TF) complex was solved at 1.8 Šresolution containing Mg2+, Ca2+ and Rb+ ions. In this structure, Rb+ replaced two Ca2+ sites in the GLA domain and occupied three non-metal sites in the protease domain. However, Rb+ was not detected at the expected Na+ site. In kinetic experiments, Na+ increased the amidolytic activity of FVIIa towards the synthetic substrate S-2288 (H-D-Ile-Pro-Arg-p-nitroanilide) by ∼20-fold; however, in the presence of Ca2+, Na+ had a negligible effect. Ca2+ increased the hydrolytic activity of FVIIa towards S-2288 by ∼60-fold in the absence of Na+ and by ∼82-fold in the presence of Na+. In molecular-dynamics simulations, Na+ stabilized the two Na+-binding loops (the 184-loop and 220-loop) and the TF-binding region spanning residues 163-180. Ca2+ stabilized the Ca2+-binding loop (the 70-loop) and Na+-binding loops but not the TF-binding region. Na+ and Ca2+ together stabilized both the Na+-binding and Ca2+-binding loops and the TF-binding region. Previously, Rb+ has been used to define the Na+ site in thrombin; however, it was unsuccessful in detecting the Na+ site in FVIIa. A conceivable explanation for this observation is provided.

Physiochemical and biological properties of the major basic protein from guinea pig eosinophil granules.

Guinea pig eosinophil granules are characterized by the presence of a basic protein of low molecular weight which accounts for greater than 50% of granule protein. This protein, termed the major basic protein (MBP), readily aggregates and becomes insoluble, and the formation of aggregates is dependent on the establishment of disulfide bonds. Analysis of concentrated preparations of MBP often revealed a series of bands which were multiples of a monomeric unit with a mol wt of approximately 11,000. Analysis of reduced and alkylated MBP on a 10% agarose column equilibrated with 6 M guanidinium chloride revealed a single polypeptide chain with a mol wt of 10,800. Amino acid analysis of the protein revealed the presence of 13% arginine, consistent with the basic character of the molecule. Four residues of tryptophan, were present, indicating that MBP is not a histone. The MBP did not increase vascular permeability when injected into the skin of guinea pigs, nor did it antagonize the effect of histamine and bradykinin in the skin. MBP also did not contract the isolated guinea pig ileum and when mixed with histamine or bradykinin did not inhibit their activity on the gut. MBP had only weak, if any, antihistaminic activity. MBP possessed weak bactericidal activity when compared to histone and then only with one strain of E. coli. MBP precipitated DNA, neutralized heparin, and activated papain. On a molar basis MBP was more active than cysteine in activating papain. These results do not point to any unique biological activity associated with MBP other than those expected of a protein as basic as it is and one which possesses reactive sulfhydryl groups. Possible functions of eosinophils based on the properties of the MBP are discussed.

Enhanced Antifibrinolytic Efficacy of a Plasmin-Specific Kunitz-Inhibitor (60-Residue Y11T/L17R with C-Terminal IEK) of Human Tissue Factor Pathway Inhibitor Type-2 Domain1.

Current antifibrinolytic agents reduce blood loss by inhibiting plasmin active sites (e.g., aprotinin) or by preventing plasminogen/tissue plasminogen activator (tPA) binding to fibrin clots (e.g., ε-aminocaproic acid and tranexamic acid); however, they have adverse side effects. Here, we expressed 60-residue (NH2NAE…IEKCOOH) Kunitz domain1 (KD1) mutants of human tissue factor pathway inhibitor type-2 that inhibit plasmin as well as plasminogen activation. A single (KD1-L17R-KCOOH) and a double mutant (KD1-Y11T/L17R- KCOOH) were expressed in Escherichia coli as His-tagged constructs, each with enterokinase cleavage sites. KD1-Y11T/L17R-KCOOH was also expressed in Pichia pastoris. KD1-Y11T/L17R-KCOOH inhibited plasmin comparably to aprotinin and bound to the kringle domains of plasminogen/plasmin and tPA with Kd of ~50 nM and ~35 nM, respectively. Importantly, compared to aprotinin, KD1-L17R-KCOOH and KD1-Y11T/L17R-KCOOH did not inhibit kallikrein. Moreover, the antifibrinolytic potential of KD1-Y11T/L17R-KCOOH was better than that of KD1-L17R-KCOOH and similar to that of aprotinin in plasma clot-lysis assays. In thromboelastography experiments, KD1-Y11T/L17R-KCOOH was shown to inhibit fibrinolysis in a dose dependent manner and was comparable to aprotinin at a higher concentration. Further, KD1-Y11T/L17R-KCOOH did not induce cytotoxicity in primary human endothelial cells or fibroblasts. We conclude that KD1-Y11T/L17R-KCOOH is comparable to aprotinin, the most potent known inhibitor of plasmin and can be produced in large amounts using Pichia.