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PubMed1988

Synaptic activation of N-methyl-D-aspartate receptors in the Schaffer collateral-commissural pathway of rat hippocampus.

1. The involvement of N-methyl-D-aspartate (NMDA) receptors in the response to single-shock (0.033 Hz) stimulation of the Schaffer collateral-commissural pathway in hippocampal slices has been investigated using current- and voltage-clamp techniques. 2. In the presence of Mg2+ (1 or 2 mM) at membrane potentials near rest, the selective NMDA antagonist D-2-amino-5-phosphonovalerate (APV) had no effect on the excitatory postsynaptic potential (EPSP) and the biphasic inhibitory postsynaptic potential (IPSP) evoked by Schaffer collateral-commissural stimulation. The recurrent IPSP evoked by antidromic stimulation of alvear fibres was also unaffected by APV. 3. The introduction of a Mg2+-free perfusate led, at high stimulus intensity, to an orthodromically evoked epileptiform discharge but little change in the recurrent IPSP. APV suppressed a large proportion of the enhanced response in Mg2+-free perfusate. 4. EPSPs and excitatory postsynaptic currents (EPSCs) evoked in Mg2+-free perfusate invariably had both APV-resistant and APV-sensitive components. Both synaptic components had similar thresholds and latencies to onset. The APV-sensitive component had a long time to peak and long duration. 5. Under current-clamp conditions in Mg2+-containing medium, an APV-sensitive component was recorded at membrane potentials of between -30 and -10 mV, but not at potentials more negative than -55 mV. 6. Under voltage-clamp, but not current-clamp, conditions in Mg2+-containing medium, a small APV-sensitive component was recorded at resting membrane potentials and increased with membrane depolarization. The difference between the current- and voltage-clamp data is attributed to the hyperpolarizing influence of conjointly activated IPSPs. 7. In the presence of Mg2+ and picrotoxin, a dual-component EPSC was recorded between -30 and +30 mV in all cells examined. The APV-resistant and APV-sensitive components had similar latencies to onset. They both had reversal potentials of between -8 and 0 mV. The APV-sensitive component had a longer latency to peak and duration than the APV-resistant component. 8. It is suggested that NMDA receptors can contribute a low-threshold and long-duration monosynaptic component of the response evoked by low-frequency stimulation of the Schaffer collateral-commissural pathway. However, under physiological conditions significant expression of this component is prevented by concurrently activated IPSPs which rapidly hyperpolarize neurones into a region where Mg2+ substantially blocks NMDA channels.

2-Amino-5-phosphonovalerate↗
PubMed2001

Tentorial enhancement on MR images is a sign of cavernous sinus involvement in patients with sellar tumors.

BACKGROUND AND PURPOSE: This study was undertaken to analyze enhancement patterns of the dura around sellar tumors and to compare the results with tumor invasion or compression of the cavernous sinuses. Postoperative enhancement patterns on MR images were compared with preoperative findings. METHODS: Contrast-enhanced coronal and sagittal MR images were examined prospectively in 96 patients with sellar tumors (65 macroadenomas, 15 microadenomas, 14 Rathke cleft cysts, and two chordomas at the sella). All patients underwent surgical treatment, and pre- and postsurgical features on MR images were compared. RESULTS: Presurgical MR images showed dural enhancement in 36.5% of the patients: asymmetric tentorial enhancement in 24 patients, symmetric tentorial enhancement in seven, and sphenoidal ridge or clivus enhancement in four. Asymmetric tentorial enhancement disappeared after surgical decompression in seven patients. For evaluation of cavernous sinus invasion ipsilateral to the enhancement, sensitivity and specificity of the asymmetric tentorial enhancement sign were 81.3% and 86.3%, respectively. Sensitivity and specificity of the sign were 42.9% and 93.6% for cavernous sinus involvement, including compression and invasion. CONCLUSION: Asymmetric tentorial enhancement is a useful sign in the diagnosis of invasion or severe compression of the cavernous sinus by sellar tumor. The sign may represent venous congestion or collateral flow in the tentorium due to obstructed flow in the medial portion of the cavernous sinus.

Adenoma↗
PubMed1986

On the probable absence of GABA receptors on the terminations of motor axon collaterals in the cat spinal cord.

When administered microelectrophoretically, GABA and the GABA-mimetic piperidine-4-sulphonic acid (P4S) appear to have no direct hyperpolarizing or depolarizing effect on the terminations of motor axon collaterals excited electrically in the ventral horn of the lumbar spinal cord of the cat. This lack of effect on axon terminals of motoneurones, which contrasts with the bicuculline-sensitive depolarization by P4S of the spinal terminals of primary afferent fibres, is consistent with previous reports of the probable absence of pharmacologically detectable GABA receptors on the spinal terminals of other central excitatory neurones, namely those of the red and lateral vestibular nuclei.

Animals↗
PubMed1992

Evaluation of collateral circulation of the hand.

In 1929, Edgar V. Allen described a noninvasive evaluation of the patency of the arterial supply to the hand of patients with thromboangitis obliterans (Am J Med Sci 1929; 178:237). In the early 1950s, Allen's test was modified (Wright I. Vascular diseases in clinical practice. Chicago: Year Book Medical Publishers, 1952) for use as a test of collateral circulation prior to arterial cannulation. This test involves the examiner occluding the patient's ulnar and radial arteries while the patient makes a fist, causing the hand to blanch. The patient is then asked to extend the fingers. After the hand is open, the examiner releases the ulnar artery while continuing to maintain pressure on the radial artery. Adequate collateral circulation is felt to be indicated by return of normal color to the hand. The patient is instructed not to hyperextend the fingers when opening the hand. Hyperextension may cause a decrease in perfusion to the arch, possibly resulting in a false interpretation of the Allen test (Anesthesiology 1972;37:356). The modified Allen's test can be performed quickly and easily, but it is susceptible to error. (With Allen's original test, both hands were tested simultaneously. The patient clenched both fists tightly for 1 minute while the examiner compressed one artery of each hand. This method helps diagnose complete occlusion, just as Allen intended. The test was later modified, however, to evaluate the adequacy of collateral circulation. To perform the modified Allen's test, the examiner compresses both arteries while the patient's fist are clenched.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2000

Contrast-enhanced three-dimensional MR angiography in the assessment of subclavian artery diseases.

The purpose of this prospective study was to determine the potential diagnostic value of 3D breath-hold contrast-enhanced MRA (CEMRA) in the evaluation of subclavian artery pathology, and to compare CEMRA and digital subtraction angiography (DSA) findings. The study group included 50 patients with suspicion of subclavian artery pathology: 40 suspected steno-occlusive disease and 10 different vascular anomalies. The MRA examinations were performed on a 1.5-T system using fast 3D sequences. A fixed dose of 40 ml Gd-DTPA was administered at 2 ml/s after previous bolus tracking. Images were analyzed to assess: subclavian depiction; luminal changes; collateral branches; and feeders of arterial venous malformations (AVM). A multireader blinded fashion was used. The CEMRA revealed an optimal agreement with DSA findings in the different types of diseases. Sensitivity and specificity were 90 and 95%, respectively, in detecting steno-occlusive disease (including functional and arteritic stenoses), and 100 and 100%, respectively, in cases of vascular anomalies (dilation, kinking, anomalous origin and AVM). Contrast-enhanced MRA can be proposed as a non-invasive, robust technique for imaging subclavian pathologies with high diagnostic performance.

Angiography, Digital Subtraction↗
PubMed1995

Vectorcardiographic monitoring to assess early vessel patency after reperfusion therapy for acute myocardial infarction.

Reperfusion therapy has lowered mortality in patients suffering from acute myocardial infarction. Failure to reperfuse is associated with an increased short- and long-term mortality. In a prospective study we used dynamic vectorcardiography to monitor 96 patients with acute myocardial infarction treated with reperfusion therapy to non-invasively assess coronary patency. The results from continuous monitoring were compared to those obtained from angiography. By using trend-analysis of QRS vector difference and ST vector magnitude, we were able to correctly identify 58 of the 70 patients (83%) with a reperfused infarct-related artery, and 19 of the 26 patients (73%) with a persistently occluded artery demonstrated at an early angiogram (diagnostic accuracy 80%). In patients with high-grade collateral flow to the infarct-related area, the results of the vectorcardiographic monitoring and of angiography showed the largest disagreement, whereas the accuracy of vectorcardiographic monitoring was high: 88% among patients without collaterals. The present results suggest that QRS complex and ST segment vectorcardiographic monitoring is a useful tool for assessing early coronary artery patency, and that dynamic vectorcardiography may help in identifying candidates for emergency coronary angiography.

Acute Disease↗
PubMed2001

Activation of multiple antibiotic resistance in uropathogenic Escherichia coli strains by aryloxoalcanoic acid compounds.

Clofibric and ethacrynic acids are prototypical pharmacological agents administered in the treatment of hypertrigliceridemia and as a diuretic agent, respectively. They share with 2,4-dichlorophenoxyacetic acid (the widely used herbicide known as 2,4-D) a chlorinated phenoxy structural moiety. These aryloxoalcanoic agents (AOAs) are mainly excreted by the renal route as unaltered or conjugated active compounds. The relatedness of these agents at the structural level and their potential effect on therapeutically treated or occupationally exposed individuals who are simultaneously undergoing a bacterial urinary tract infection led us to analyze their action on uropathogenic, clinically isolated Escherichia coli strains. We found that exposure to these compounds increases the bacterial resistance to an ample variety of antibiotics in clinical isolates of both uropathogenic and nonpathogenic E. coli strains. We demonstrate that the AOAs induce an alteration of the bacterial outer membrane permeability properties by the repression of the major porin OmpF in a micF-dependent process. Furthermore, we establish that the antibiotic resistance phenotype is primarily due to the induction of the MarRAB regulatory system by the AOAs, while other regulatory pathways that also converge into micF modulation (OmpR/EnvZ, SoxRS, and Lrp) remained unaltered. The fact that AOAs give rise to uropathogenic strains with a diminished susceptibility to antimicrobials highlights the impact of frequently underestimated or ignored collateral effects of chemical agents.

Anti-Bacterial Agents↗
PubMed1986

Failure of pyruvate to salvage myocardium after prolonged ischemia.

Thrombolytic therapy for acute coronary occlusion may be more effective if combined with substrate-enhanced reperfusion. In this study, we examined the utility of pyruvic acid, an important metabolic substrate, in salvaging ischemic myocardium. Twenty-six anesthetized dogs underwent 3 h of circumflex coronary occlusion followed by 90 min of reperfusion with administration of intracoronary pyruvate or vehicle. To test the sensitivity of the model in detecting differences in infarct size, eight additional dogs underwent coronary occlusion of shorter duration (45 min), an intervention that is known to reduce infarct size. Collateral perfusion to the ischemic zone during coronary occlusion was similar in experimental and control groups. Whereas a shorter duration of occlusion (45 min) decreased the infarct-to-risk area ratio by 54% compared with a longer duration of occlusion (90 min), neither early (15 min prior to occlusion) nor late (3 h after occlusion) onset of intracoronary infusion of pyruvate shifted the infarct-risk relationship (control: y = 74x - 8.7, r = 0.99; early infusion: y = 0.76x - 9.5, r = 0.85; late infusion: y = 0.58x - 5.5, r = 0.79). The failure of intracoronary administration of pyruvate to limit infarct size raises questions as to its potential clinical utility in the setting of acute myocardial ischemia.

Animals↗
PubMed1996

Temporal resolution of activity-dependent pH shifts in rat hippocampal slices.

1. The rise time of activity-dependent extracellular pH shifts was measured in the CA1 stratum radiatum of rat hippocampal slices by recording pH-sensitive fluorescence of a fluorescein-conjugated dextran. Optical data were compared with simultaneous pH microelectrode recordings. 2. The pH shifts generated by CO2 or by stimulation of the Schaffer collaterals were paralleled by shifts in fluorescence emissions at 535 nm when the probe was excited with 490-nm light (delta F490). Emissions at 535 nm induced by 440-nm light were unchanged in these paradigms. 3. A train of three stimuli at 100 Hz was repeated at 30-s intervals and the stimulus-triggered delta F490 was averaged. The mean rise time of the delta F490 was 69 +/- 24 (SE) ms (range 20-200 ms, n = 6). The mean increase in emission was 0.75 +/- 0.22% of baseline, associated with a pH microelectrode response of +0.06 +/- 0.02 unit pH. 4. These data demonstrate that synaptically evoked alkaline transients develop within tens of milliseconds. The occurrence of the alkalinization in the same time frame as excitatory postsynaptic currents indicates that these pH shifts arise with sufficient speed to modulate synaptic transmission.

Alkalies↗
PubMed1996

PD 81,723, an allosteric enhancer of the A1 adenosine receptor, lowers the threshold for ischemic preconditioning in dogs.

PD 81,723 (PD) acts allosterically to increase agonist binding to A1 adenosine receptors and to enhance functional A1 receptor-mediated responses in the heart and other tissues. To determine if PD lowers the threshold for ischemic preconditioning (PC), pentobarbital-anesthetized dogs were subjected to 60 minutes of left anterior descending coronary artery (LAD) occlusion and 3 hours of reperfusion. Ischemic PC was produced by either 2.5 or 5 minutes of LAD occlusion 10 minutes before the 60-minute occlusion. PD (100 micrograms/kg total dose, 5 to 50 mumol/L in coronary arterial blood) or vehicle was infused intracoronarily for 17.5 minutes before the 60-minute occlusion period in non-PC dogs or in dogs preconditioned with 2.5 minutes of ischemia. Myocardial infarct size was determined by triphenyltetrazolium staining and expressed as a percentage of the area at risk. Compared with the control group (26.3 +/- 3.6%, mean +/- SEM), infarct size was not significantly affected by 2.5 minutes of PC alone (23.4 +/- 4.2%) or by PD alone (26.5 +/- 1.7%) but was decreased by PD + PC (14.6 +/- 1.7%, P < .05) or by a longer period (5 minutes) of PC alone (12.5 +/- 3.3%). The intravenous administration of the selective antagonist of A1 adenosine receptors, 8-cyclopentyl-1,3-dipropylxanthine (1 mg/kg), or the ATP-sensitive K+ channel blocker, glibenclamide (0.3 mg/kg), for 15 minutes before PD + PC blocked the protection (23.6 +/- 2.3% or 25.9 +/- 3.3%, respectively). None of the compounds studied affected systemic hemodynamics, collateral blood flow, or AAR. To determine which subtypes of canine adenosine receptors were affected by 10 mumol/L PD, radioligand binding studies were conducted using membranes derived from COS-7 cells expressing recombinant canine receptors and agonist radioligands. PD enhanced the binding of [125I]N6-4-amino-3-iodobenzyladenosine (125I-ABA) to A1 receptors by increasing the t1/2 for dissociation by 2.18-fold, but PD had no effect on the dissociation kinetics of 125I-ABA from A3 receptors or [125I]-[2-(4-amino-3-iodo-phenyl)ethylamino] adenosine from A2A receptors. Glibenclamide at concentrations up to 10 mumol/L had no effect on the binding of radioligands to recombinant canine A1, A2A, or A3 receptors. These data suggest that PD reduces the amount of time required for ischemia to produce preconditioning by enhancing adenosine binding to its A1 receptor. Glibenclamide prevents the protection afforded by A1 receptor activation by a mechanism not involving adenosine receptor blockade.

Allosteric Regulation↗
PubMed2001

Cardiac Magnetic Resonance Imaging for the Assessment of Myocardial Angiogenesis.

Research in biology and applications of growth factors in coronary artery disease (CAD) has progressed considerably over recent years. Vascular endothelial growth factor and fibroblast growth factor-2 have been more successful in animal models of myocardial ischemia and Phase I studies than in placebo-controlled trials. However, cardiac magnetic resonance (CMR), with its higher sensitivity and specificity indices for identification of CAD, has not been extensively used in trials of angiogenic therapies. Data in animals and in patients suggest that CMR can reliably identify collateral vessels. Therefore, we hypothesize that CMR may depict collateralization induced by angiogenic therapy better than currently used nuclear perfusion imaging modalities. Versatility of the assessment of myocardial function and perfusion in one imaging session, combined with the noninvasive nature of the test, may considerably lower the cost of clinical trials. Use of CMR-derived surrogate end points may provide better risk stratification and assessment of efficacy in patients receiving growth factor therapy.

Journal Article↗
PubMed1996

[Diagnosis of acute rupture of the anterior cruciate ligament. Value of ultrasonic in addition to clinical examination].

Post-traumatic knee injuries often deteriorate if reuptures of anterior cruciate ligaments (ACL) are not treated adequately. Further diagnostic procedures are required if pain-induced muscle contraction impairs clinical examination. The clinical relevance of sonography, however, for the diagnosis of ACL ruptures is controversial. Within 25 months, 74 patients were preoperatively evaluated clinically and by ultrasound. 58 ruptures of the ACL and 21 lesions of the collateral ligaments were confirmed by arthroscopy or arthrotomy. In 16 cases a menisceal tear was found, four patients had a luxation of the patella, and two had PCL ruptures. The sensitivity of the Lachman test was 93%, of the anterior drawer test 68% and of the pivot shift test 48%. Ultrasound diagnosis revealed 88% of all ACL ruptures (91% if patients with bony ruptures of the ACL were excluded). In 75% of ACL ruptures, a popping sensation was reported by the patients. In the case of uncertain diagnosis, examination with ultrasound could be easily performed before further operative diagnostic procedures are scheduled.

Acute Disease↗
PubMedDate not supplied

Potential of CT angiography in acute ischemic stroke.

PURPOSE: To study the ability of CT angiography to show intracranial arterial occlusion and collateral blood flow in patients with acute stroke. METHODS: Twenty-one patients with acute nonhemorrhagic stroke were studied prospectively with conventional CT, CT angiography, and digital subtraction angiography. On the basis of CT angiographic findings, two neuroradiologists independently assessed the site of arterial occlusion, the contrast enhancement in arterial branches beyond the occlusion as a measure of collateral blood supply, and the extent of diminished parenchymal enhancement; they then predicted the extent of ischemic infarction. RESULTS: Both raters correctly assessed all trunk occlusions of the basilar artery (n = 4), the internal carotid artery (n = 4), and the middle cerebral artery (n = 9). The chance adjusted interrater agreement was kappa = .78. The assessment of branch occlusions of the middle cerebral artery was less reliable. The agreement rate in judging the collateral state in 17 occlusions in the anterior cerebral circulation was 88%. The size of 21 (62%) of 34 hemispheric infarctions was predicted correctly. CONCLUSION: CT angiography quickly and reliably adds important information to conventional CT studies in cases of acute ischemic stroke. It shows the site of occlusion, the length of the occluded arterial segment, and the contrast-enhanced arteries beyond the occlusion as an estimate of collateral blood flow.

Adult↗
PubMed1999

Detection of accessory renal arteries with virtual vascular endoscopy of the aorta.

PURPOSE: To evaluate the diagnostic accuracy of virtual vascular endoscopy (VVE) in the detection of accessory renal arteries. METHODS: We retrospectively reviewed the CT angiography data sets of 67 patients (29 male and 38 female; age range 17-72 years, mean age 53 years) imaged for the study of the renal arteries, and affected by renovascular hypertension. All patients also had intraarterial digital subtraction angiography (DSA). CT angiography data sets were processed to obtain maximum intensity projection (MIP) and surface-rendered VVE of the aorta. Axial images, MIP, and VVE were evaluated separately and in combination in the detection of accessory renal arteries. Their results in terms of sensitivity and specificity were then compared with DSA. RESULTS: Axial images had a sensitivity of 88% and specificity of 94% for accessory renal artery detection, MIP had a sensitivity of 88% and specificity of 98%, and VVE had a sensitivity of 63% and a specificity of 88% (p < 0.05 vs DSA), but these increased to 88% and 98% respectively if endoscopic views were integrated with the other display techniques. CONCLUSION: VVE based on surface rendering does not add substantial benefits to CTY angiography; by contrast MIP is the most accurate display technique for the detection of accessory renal arteries.

Adolescent↗
PubMed2004

[Clinical implication of parameter-optimized 3D-FISP MR angiography (MRA) in children with aortic coarctation: comparison with catheter angiography].

PURPOSE: To implement parameter-optimized 3D-FISP MR angiography (MRA) with interleaved double-slab excitation and to compare the result with catheter angiography in children with aortic coarctation. MATERIALS AND METHODS: Eighteen children aged 2 - 15 years (mean 9.1 years) underwent MR imaging on a 1.5T body scanner (Magnetom Vision, Siemens, Germany). All patients had undergone correlative catheter angiography. T1-weighted turbo spin echo (TSE) images (TR 600 ms, TE 17 ms, flip 160 degrees, slice thickness 2 - 4 mm) were obtained in axial and parasagittal orientation, followed by an optimized 3D-FISP MR angiography in a sagittal plane (TR 12.5 ms, TE 5.5 ms, flip 22 degrees, matrix 256 x 256, slice thickness 1.25 mm). All children were sedated but on spontaneous breathing. Image quality was graded by two experienced reviewers using a 4-point scoring system. Source images and reformatted maximum intensity projections (MIP) were analyzed for blood-tissue contrast as well as size and focal stenoses of the aortic arch. RESULTS: Aortic coarctation was found in 13 of 18 patients, using the 3D-FISP MRA. A high correlation value (r = 0.96) was found compared to catheter angiography. Image quality was high in 94 % with well defined blood-tissue contrast in all cases. The sensitivity to flow and breathing motion was low. Examination time was about 15 minutes depending on volume of interest and heart rate. Diagnostic accuracy has shown improvement using a combined analysis of source and MIP images. The mentioned technique has provided an excellent display of thoracic vasculature. CONCLUSION: MR imaging represents an excellent tool for non-invasive examination of the cardiovascular system of children. The 3D-MRA allows the recording of a large 3D data set without the use of contrast agent and within an adequate measurement period, particularly in small infants unable to hold their breath. In addition, hemodynamic significance of aortic coarctation, the existence of collateral vessels and other congenital heart diseases can be described reliably by using this technique.

Adolescent↗
PubMed1984

Mechanisms of ventricular arrhythmias in multivessel coronary disease: the effects of collateral zone ischemia.

We studied 15 anesthetized dogs with 4-day-old anterior wall infarctions caused by previous ligation of the left anterior descending coronary artery. Left circumflex artery (LCA) stenosis induced an average 41% decrease in collateral-dependent flow to the surviving anterior wall (epicardium) and only a 10% decrease to the normal posterior epicardial wall. Electrogram changes in 12 dogs consisted of fractionation and delay of anterior wall electrograms leading to bridging electrical activity between sinus beats and ventricular ectopic beats in five dogs. No similar electrogram changes were noted in posterior wall recordings. Ventricular paced beats induced ventricular tachycardia arising from the anterior wall in four dogs only after LCA stenosis. LCA stenosis in anterior myocardial infarction may be arrhythmogenic because of increased sensitivity of the surviving tissues, which have been electrically deranged by the ischemic/infarction process.

Angina Pectoris↗
PubMed2002

Sonography of diffuse liver disease.

Sonography is often the first imaging procedure performed in the evaluation of individuals with suspected liver disease. Evaluation for biliary dilatation is always performed, because bile duct obstruction can cause abnormal liver test results, raising the suspicion of liver disease. Ultrasound is a useful but imperfect tool in evaluating diffuse liver disease. We discuss the uses and limitations of sonography in evaluating parenchymal liver disease. Sonography can show hepatomegaly, fatty infiltration of the liver, and cirrhosis, all with good but imperfect sensitivity and specificity. Sonography is of limited usefulness in acute hepatitis. Increased parenchymal echogenicity is a reliable criterion for diagnosing fatty liver. Cirrhosis can be diagnosed in the correct clinical setting when the following are present: a nodular liver surface, decreased right lobe-caudate lobe ratio, and indirect evidence of portal hypertension (collateral vessels and splenomegaly). Ultrasound plays an important role in the imaging of conditions and procedures common in patients with diffuse liver disease.

Carcinoma, Hepatocellular↗
PubMed2026

Monitoring kinetic changes and restriction of influenza A virus RNA species during infection using a Flu-Stranded CRISPR platform.

UNLABELLED: Influenza A virus (IAV) generates three closely related RNA species: viral RNA (vRNA), complementary RNA (cRNA), and messenger RNA (mRNA), whose strand-specific quantification remains limited by sensitivity and quantitative dynamic range, particularly at low RNA abundance. Here, we developed Flu-Stranded CRISPR-Cas12a, a strand-specific detection platform integrating tagged reverse transcription, segment-specific PCR, and Cas12a collateral cleavage to support quantitative analysis of all three RNA species across a broad dynamic range. The assay enables reliable detection down to 102 copies per reaction, extending the lower quantitative boundary relative to both SYBR Green and TaqMan reverse transcription quantitative PCR (RT-qPCR) under matched conditions. Validated in infected cell lines, murine lung tissues, and clinical nasopharyngeal specimens, the platform enabled subtype-discriminating, strand-resolved detection, including samples near or below the quantitative range of SYBR Green RT-qPCR. Using finely resolved infection time-course analyses in NP and NA segments, we identified a reproducible early vRNA decline within the early post-infection phase. This decline was partially attenuated in RIG-I knockout A549 cells, while subsequent vRNA accumulation was enhanced, consistent with a modulatory rather than essential role for RIG-I in early viral RNA dynamics. Subcellular fractionation localized this decline to cytoplasmic incoming genomes. In contrast, importazole-mediated inhibition of nuclear import abolished vRNA recovery without affecting the early decline, indicating that nuclear entry functionally separates early genome reduction from subsequent productive replication. These findings establish Flu-Stranded CRISPR-Cas12a as a strand-resolved framework for monitoring IAV RNA dynamics and reveal an early window of genome vulnerability during cytoplasmic transit that shapes infection outcome. IMPORTANCE: The early fate of incoming influenza virus genomes remains unclear, limiting our understanding of how infection is established or aborted in host cells. We developed Flu-Stranded CRISPR-Cas12a, a strand-specific platform for sensitive and quantitative analysis of influenza viral RNA (vRNA), complementary RNA (cRNA), and messenger RNA (mRNA) across experimental and clinical samples. Using high-resolution time-course analysis, we identified a reproducible early decline in vRNA during the post-entry phase. Our data suggest that this early genome loss arises from multiple processes, with RIG-I acting as a modulatory factor rather than a primary driver. Subcellular fractionation localized this effect to cytoplasmic incoming genomes, whereas importin-&#x3b2;-mediated nuclear entry was required for subsequent vRNA recovery. These findings support a model of an early cytoplasmic phase of genome attrition that is distinct from replication and provide a framework for understanding early influenza RNA kinetics and for guiding strand-resolved diagnostics and antiviral evaluation.

CRISPR-Cas12a↗