The small-molecule MERTK inhibitor UNC2025 decreases platelet activation and prevents thrombosis

Essentials Signaling by Gas6 through Tyro3/Axl/Mer receptors is essential for stable platelet aggregation. UNC2025 is a small molecule inhibitor of the Mer tyrosine kinase. UNC2025 decreases platelet activation in vitro and thrombus formation in vivo. UNC2025's anti-platelet effect is synergistic with inhibition of the ADP receptor, P2Y12 .

SUMMARY

Background Growth arrest-specific protein 6 signals through the TAM (TYRO-3-AXL-MERTK) receptor family, mediating platelet activation and thrombus formation via activation of the aggregate-stabilizing αIIb β3 integrin. Objective To describe the antithrombotic effects mediated by UNC2025, a small-molecule MERTK tyrosine kinase inhibitor. Methods MERTK phosphorylation and downstream signaling were assessed by immunoblotting. Light transmission aggregometry, flow cytometry and microfluidic analysis were used to evaluate the impact of MERTK inhibition on platelet activation and stability of aggregates in vitro. The effects of MERTK inhibition on arterial and venous thrombosis, platelet accumulation at microvascular injury sites and tail bleeding times were determined with murine models. The effects of combined treatment with ADP-P2Y1&12 pathway antagonists and UNC2025 were also evaluated. Results and Conclusions Treatment with UNC2025 inhibited MERTK phosphorylation and downstream activation of AKT and SRC, decreased platelet activation, and protected animals from pulmonary embolism and arterial thrombosis without increasing bleeding times. The antiplatelet effect of UNC2025 was enhanced in combination with ADP-P2Y1&12 pathway antagonists, and a greater than additive effect was observed when these two agents with different mechanisms of inhibition were coadministered. TAM kinase signaling represents a potential therapeutic target, as inhibition of this axis, especially in combination with ADP-P2Y pathway antagonism, mediates decreased platelet activation, aggregate stability, and thrombus formation, with less hemorrhagic potential than current treatment strategies. The data presented here also demonstrate antithrombotic activity mediated by UNC2025, a novel translational agent, and support the development of TAM kinase inhibitors for clinical applications.

Filgrastim treatment of acute myelogenous leukemia (M7) relapse after allogeneic peripheral stem cell transplantation resulting in both graft-versus-leukemia effect with cytogenetic remission and chronic graft-versus-host disease manifesting as polyserositis and subsequent bronchiolitis obliterans with organizing pneumonia

Filgrastim (granulocyte colony-stimulating factor) has recently been reported to successfully treat patients with leukemic relapse after allogeneic peripheral stem cell transplantation (PSCT). However, the majority of the patients who responded also developed graft-versus-host disease (GVHD). Polyserositis as a manifestation of GVHD is a rare phenomenon. We report the first case of polyserositis following the use of filgrastim to treat a patient with acute myelogenous leukemia (M7), who had relapsed after an initially successful allogeneic PSCT. The polyserositis manifested with effusions and was initially controlled with high doses of steroids and pericardial stripping; however, after a quiescent period the patient eventually developed bronchiolitis obliterans with organizing pneumonia that required additional immunosuppressive therapy. We review the literature on GVHD-associated polyserositis and offer potential explanations for its pathogenesis.

Utility of zanamivir for chemoprophylaxis of concomitant influenza A and B in a complex continuing care population

OBJECTIVE

To describe compliance with and the safety and prophylactic efficacy of zanamivir among patients at risk of developing influenza-related complications after exposure to both influenza A and B viruses.

DESIGN

Nonrandomized trial using both historical and contemporaneous controls from ward populations within the same facility.

SETTING

A 547-bed urban hospital providing complex continuing care and rehabiltation.

PATIENTS

Fifty patients on a single ward concomitantly exposed to both influenza A and B during an influenza outbreak.

INTERVENTIONS

All patients were screened for symptoms of influenza and nasopharyngeal swabs were sent for viral culture prior to treatment (two oral inhalations [2 x 5 mg] twice daily for 5 days) or prophylaxis (two oral inhalations [2 x 5 mg] once daily for 14 days) with zanamivir. Patient symptoms, compliance, and drug tolerance were monitored daily. Demographic data, comorbidities, vaccination status, and functional status (Katz score) were collected for all patients.

RESULTS

The mean age of the patients was 70.6 years (standard deviation, +/- 16.4 years). Ninety-four percent had two or more comorbidities, 71% were dependent in two or more activities of daily living, 63% had been vaccinated for influenza, and 82% had received amantadine. Zanamivir was well tolerated, with 93% of the patients completing their course. The efficacy for preventing symptomatic infection was 82% and 91% (95% confidence interval, 62% to 98%) based on historical and contemporaneous controls, respectively.

CONCLUSION

These data suggest that zanamivir can be used safely and effectively as a prophylactic agent in the management of influenza outbreaks in a complex continuing care population with multiple comorbidities.

Maternal serum screening for Down syndrome in a teaching hospital in Hong Kong

OBJECTIVE

To study prospectively the use of maternal serum alpha-fetoprotein (AFP) and total beta-human chorionic gonadotropin (hCG) concentrations for screening of Down syndrome in Hong Kong.

METHODS

AFP and total beta-hCG were measured in serum samples from 1638 singleton Chinese pregnancies at 14-22 weeks of gestation, recruited over a twelve-month period. Gestational ages were determined by ultrasonographic parameters measured at the same visit as the test for all cases. The gestational-age-specific and weight-adjusted medians for serum AFP and total beta-hCG were calculated. Risk for fetal Down syndrome (FDS) was derived by mathematical modeling of the medians together with maternal age. Amniocenteses were offered to women with a calculated FDS risk of 1:270 or greater.

RESULTS

The gestational-age-specific and weight-adjusted medians for maternal serum AFP were similar to previous studies while that of total beta-hCG were higher. A total of 101 patients (6.1%) were classified as being high risk for FDS, including 3.4% (48/1394) of those younger than 35 years of age and 21.7% (53/244) of those who were 35 or above. There were 4 cases of Down syndrome, 1 case of Tumer syndrome and 1 of Edward syndrome. Three out of the four cases of Down syndrome were screened positive, corresponding to a detection rate of FDS of 75%. A case of Tumer syndrome was also screened positive. A case of trisomy 18 was found to have very low levels of AFP [0.262 multiple of median (MoM)] and total beta-hCG (0.115 MoM).

CONCLUSIONS

Maternal serum screening using double biochemical markers (AFP and total beta-hCG) in combination with gestational dating by ultrasonography is effective in the detection of fetal Down syndrome and possibly other chromosomal disorders in Chinese pregnant women.

Group D adenoviruses infect primary central nervous system cells more efficiently than those from group C

Group C adenovirus-mediated gene transfer to central nervous system cells is inefficient. We found that wild-type group D viruses, or recombinant adenovirus type 2 (Ad2) (group C) modified to contain Ad17 (group D) fiber, were more efficient in infecting primary cultures of neurons. Together with studies on primary vascular endothelial cells and tissue culture cell lines, our results indicate that there is not a universally applicable adenovirus serotype for use as a gene transfer vector.

Endodontic treatment of mandibular molars with concrescence

Endodontic treatment of a permanent mandibular first molar and a second molar presumably joined by cementum is presented. This case illustrates the difficulty in interpreting the vitality testing in such a situation. It also suggests possible irreversible pulp injury of a vital healthy tooth caused by extension of the inflammatory periapical pathosis of the adjacent tooth.

Evaluation of the Merifluor immunofluorescent assay for the detection of Cryptosporidium and Giardia in sodium acetate formalin-fixed stools

The Merifluor Cryptosporidium/Giardia direct immunofluorescent assay (MFDFA) was used for the blinded detection of Cryptosporidium and Giardia in 100 previously tested sodium acetate formalin (SAF)-preserved fecal specimens. Examination for ova and parasites by formalin-ether concentration followed by iron-hematoxylin and Kinyon staining had demonstrated Cryptosporidium (n = 32), Giardia (n = 20) and both Giardia and Cryptosporidium (n = 5). The MFDFA detected one additional specimen with Cryptosporidium and another with Giardia and was rapid, accurate, and simple to perform.

Heterodonty and patterns of tooth replacement in Crocodylus niloticus

Patterns of tooth replacement in the Nile crocodile Crocodylus niloticus were evaluated in the lateral radiographs of six dried skulls of 1-year-old individuals. Additionally, the ontogeny of the succession of teeth in this species was investigated in four embryos and a hatchling, which were serially sectioned. Three-dimensional, computer-generated reconstructions of these individuals suggested that there was a regular pattern of odontogenic progression. Three morphogenetic zones could be identified in each of the age classes: an incisor, a canine, and a molar region. It was thus concluded that the Nile crocodile is hetero- rather than homodont. Zahnreihen, or tooth rows, with a periodicity of one were easily identified. © 1993 Wiley-Liss, Inc.

Suppression of lymphocyte proliferation by proteins secreted by cultured Sertoli cells

Secreted proteins from cultured rat Sertoli cells were assessed for effects on phytolectin-stimulated rat splenic lymphocytes. Sertoli cell proteins (SCP) suppressed DNA, RNA and protein synthesis in stimulated rat splenic lymphocytes whether added at 0, 4, 24 and 48 h after culture initiation. SCP preparations were not toxic to cells. SCP suppressive activity was heat stable but was not associated with the carbohydrate component of SCP preparations. SCP also suppressed the proliferation of lymphoid and non-lymphoid cell lines from several different animal species but did not inhibit proliferation-independent lysis of YAC-1 target cells by rat natural killer cells. These results suggest that Sertoli cells synthesize inhibitory factors that might be secreted into seminal plasma. Furthermore, our results demonstrate that one mode of action of these factors is suppression of cell proliferation.

Microbiological diagnosis of peritonitis in patients on continuous ambulatory peritoneal dialysis

The fast and accurate etiological diagnosis of peritonitis in patients on continuous ambulatory peritoneal dialysis is essential. The concentration of larger volumes of peritoneal fluids may yield more isolates than conventional methods. The removal of antibiotics present in the fluids as a consequence of therapy by washing or using antibiotic-removing resins increases the yield considerably. The use of anaerobic culture media is justified if fecal organisms are suspected as the cause of the infection.

Relative stabilities of the two quaternary conformations of human fetal hemoglobin

The pH dependence of several functional properties of human fetal and adult hemoglobins have been studied to determine the relative stabilities of the high and low affinity (R and T) quaternary conformations of the two proteins under different conditions. Fetal aqumethemoglobin undergoes changes in sulfhydryl reactivity, absorption spectrum, and circular dichroism in the presence of insitol hexaphospahte which are consistent with a transition from the R to T quaternary state, but only at pH values below 6.8. In adult hemoglobin this transition can be induced pH values below 7.2. Even in the absence of phosphates, the ultraviolet (uv) circular dichroism spectrum of fetal aquomethemoglobin at low pH indicates the presence of some T conformation. The initial value for the second-order rate constant for combination of fetal deoxyhemoglobin with carbon monoxide is comparable to that for adult hemoglobin in the absence of organic phosphates and is not reduced by organic phosphates as much as that for the adult protein. The apparent first-order rate constant for dissociation of CO from fully liganded fetal hemoglobin, measured by replacement with NO, increases threefold in the absence of organic phosphates, and fourfold in the presence of organic phosphates, with decreasing pH; the midpoint of the pH dependent transition occurs around 6.8. A similar increase in the apparent first-order rate constant for O2 dissociation as measured by replacement with CO, can also be seen with decreasing pH. NO-hemoglobin F can be converted to the T state even when fully liganded simply by lowering the pH, as judged by uv circular dichroism, visible difference spectrum in the region of the alpha and beta bands, and a dramatic increase in the rate of NO dissociation, measured by replacement with CO in the presence of dithionite. These results are all consistent with a model for fetal hemoglobin in which the organic phosphate site may be functionally weakened by replacement of a residue involved in ionic interactions with the negatively charged phosphate groups, but in which the low affinity T conformation is intrinsically more stable than that of adllt hemoglobin. According to this model,the differences between fetal and adult hemoglobin can be accounted for primarily in terms of the relative stabilities of R and T conformations in each of the proteins with differences in the intrinsic properties of the individual conformations contributing effects of only secondary importance.