The Indian Consensus Document on cardiac biomarker

Automated Synthesis and Initial Evaluation of (4'-Amino-5',8'-difluoro-1'H-spiro[piperidine-4,2'-quinazolin]-1-yl)(4-[18F]fluorophenyl)methanone for PET/MR Imaging of Inducible Nitric Oxide Synthase

Background

Inducible nitric oxide synthase (iNOS) plays a crucial role in neuroinflammation, especially microglial activity, and may potentially represent a useful biomarker of neuroinflammation. In this study, we carefully defined a strategic plan to develop iNOS-targeted molecular PET imaging using (4′-amino-5′,8′-difluoro-1′H-spiro[piperidine-4,2′-quinazolin]-1-yl)(4-fluorophenyl)methanone ([¹⁸F]FBAT) as a tracer in a mouse model of lipopolysaccharide- (LPS-) induced brain inflammation.

Methods

An in vitro model, murine microglial BV2 cell line, was used to assess the uptake of [¹⁸F]FBAT in response to iNOS induction at the cellular level. In vivo whole-body dynamic PET/MR imaging was acquired in LPS-treated (5 mg/kg) and control mice. Standard uptake value (SUV), total volume of distribution (V_t), and area under the curve (AUC) based on the [¹⁸F]FBAT PET signals were determined. The expression of iNOS was confirmed by immunohistochemistry (IHC) of brain tissues.

Results

At the end of synthesis, the yield of [¹⁸F]FBAT was 2.2–3.1% (EOS), radiochemical purity was >99%, and molar radioactivity was 125–137 GBq/μmol. In vitro, [¹⁸F]FBAT rapidly and progressively accumulated in murine microglial BV2 cells exposed to LPS; however, [¹⁸F]FBAT accumulation was inhibited by aminoguanidine, a selective iNOS inhibitor. In vivo biodistribution studies of [¹⁸F]FBAT showed a significant increase in the liver and kidney on LPS-treated mice. At 3 h postinjection of LPS, in vivo, the [¹⁸F]FBAT accumulation ratios at 30 min post intravenous (i.v.) radiotracer injection for the whole brain, cortex, cerebellum, and brainstem were 2.16 ± 0.18, 1.53 ± 0.25, 1.41 ± 0.21, and 1.90 ± 0.12, respectively, compared to those of mice not injected with LPS. The mean area under the curve (AUC_0-30min), total volume of distribution (V_t, mL/cm³), and K_i (influx rate) of [¹⁸F]FBAT were 1.9 ± 0.21- and 1.4 ± 0.22-fold higher in the 3 h LPS group, respectively, than in the control group. In the pharmacokinetic two-compartment model, the whole brain K_i of [¹⁸F]FBAT was significantly higher in mice injected with LPS compared to the control group. Aminoguanidine, selective iNOS inhibitor, pretreatment significantly reduced the AUC_0-30min and V_t values in LPS-induced mice. Quantitative analysis of immunohistochemically stained brain sections confirmed iNOS was preferentially upregulated in the cerebellum and cortex of mice injected with LPS.

Conclusion

An automated robotic method was established for radiosynthesis of [¹⁸F]FBAT, and the preliminary in vitro and in vivo results demonstrated the feasibility of detecting iNOS activity/expression in LPS-treated neuroinflammation by noninvasive imaging with [¹⁸F]FBAT PET/MRI.

Prognostic Role of B-Type Natriuretic Peptide in Adults with Acute Dyspnea Requiring Emergency Admission

Objective:

The aim of the study was to evaluate the role of B-type natriuretic peptide (BNP) in patients presenting with acute dyspnea admitted in emergency services.

Materials and Methods:

A prospective observational study was conducted on 100 patients presenting to the emergency of Dayanand Medical College and Hospital and Hero DMC Heart Institute with acute dyspnea of <48 h duration, in which BNP levels were done on arrival to emergency.

Results:

BNP levels were significantly higher in patients having left ventricular dysfunction, both systolic and diastolic. Patients with systolic dysfunction had slightly higher BNP (1251.50 ±950.14 pg/mL) compared to patients with diastolic dysfunction (905.62±618.10 pg/mL) though statistically insignificant (P = 0.055). BNP levels were also inversely related to ejection fraction. Mean BNP levels in patients with EF <31%, 31%–45%, 46%–59%, and ≥60% were 1464.63 ± 1058.29, 968.24 ± 751.59, 841.64 ± 503.41 and 781.67 ± 504.21 (P = 0.009), respectively. Patients having higher BNP levels had significantly prolonged duration of stay compared to patients with lower BNP. Patients who expired had slightly higher levels of BNP though statistically nonsignificant. BNP had no significant statistical relation with age, heart rate, creatine phosphokinase-MB, Trop-T levels, systolic blood pressure.

Conclusion:

We conclude that high BNP levels are a marker of cardiac dysfunction and increased duration of hospital stay in patients presenting to the emergency with acute dyspnea. Hence, BNP can be used as a screening test for the evaluation and management of dyspnea.