Transient myocardial contrast after initial exposure to diagnostic ultrasound pressures with minute doses of intravenously injected microbubbles. Demonstration and potential mechanisms

BACKGROUND

We have observed a transient but significant increase in myocardial contrast intensity with intravenously injected perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles that occurs on initial exposure to pulsed ultrasound (transient-response imaging). The characteristics and magnitude of this response were examined in the present study.

METHODS AND RESULTS

In 14 dogs, the myocardial contrast intensity produced by transient-response imaging (TRI) was compared with conventional 30-Hz imaging (CI) after a 0.005 to 0.030 mL/kg intravenous injection of PESDA. TRI was produced either by measuring myocardial contrast during triggered (1 pulse per cardiac cycle) ultrasound or by withholding real time ultrasound transmission until after microbubbles had entered the myocardium after intravenous injection. Both first-harmonic imaging (2.0 to 3.5 MHz) and second-harmonic imaging (2.0 to 2.5 MHz fundamental, 4.0 to 5.0 MHz received) were used. TRI produced over three times the anterior myocardial contrast intensity of CI (36 +/- 12 U TRI versus 11 +/- 11 U CI; P < .01), with visually better anterior and posterior myocardial contrast. The spatial extent of myocardial ischemia was easily visualized after intravenous PESDA by use of TRI and correlated closely with risk area as measured with Monastral blue (r = .99, P = .002).

CONCLUSIONS

TRI produces significantly greater myocardial contrast than CI and may dramatically enhance the ability of intravenous ultrasound contrast agents to identify myocardial perfusion abnormalities.

Improved myocardial contrast with second harmonic transient ultrasound response imaging in humans using intravenous perfluorocarbon-exposed sonicated dextrose albumin

OBJECTIVES

The objectives of this study were to determine whether a new method of ultrasound imaging (transient response imaging) could improve the myocardial contrast after intravenous injections of perfluorocarbon-exposed sonicated dextrose albumin microbubble contrast medium in humans.

BACKGROUND

We have shown in animals that very low doses of intravenous contrast medium can produce transient but significantly better myocardial contrast when diagnostic ultrasound pulses are interrupted (delivered only once per cardiac cycle) instead of conventional 25- to 30-Hz frame rate imaging.

METHODS

In 14 patients with normal rest wall motion, the peak myocardial contrast produced by transient response imaging was compared with that produced by conventional harmonic ultrasound imaging after injections of low doses (0.0025 to 0.01 ml/kg) of intravenous contrast medium. All studies were performed with second harmonic imaging (2.0 to 2.5 MHz-transmitted frequency). Blood pressure, oxygen saturation, respiratory rate and pulse were monitored before and after each injection.

RESULTS

The intravenous contrast medium in the doses given produced no hemodynamic changes and no significant side effects in any patients. Overall, the mean (+/-SD) anterior and posterior myocardial contrast produced was significantly greater with transient response imaging than with conventional harmonic ultrasound imaging (anterior: 37 +/- 20 U transient response imaging vs. 18 +/- 14 U conventional harmonic imaging; posterior: 17 +/- 14 U transient response imaging vs. 5 +/- 5 U conventional; p< 0.01). With the sample size of 14 patients, the study had 80% power to detect a true difference of 18 U for anterior myocardial contrast and 90% power to detect a difference of 12 U for posterior contrast. Visually evident anterior or apical myocardial contrast was observed in 14 of 15 patients with transient response imaging but in only 7 patients with conventional harmonic imaging. Posterior or basal myocardial contrast was evident in 10 patients with transient response imaging but in only 1 patient with conventional harmonic imaging.

CONCLUSIONS

Transient response imaging produces significantly better myocardial contrast than conventional harmonic imaging in humans and can be produced safely with minute quantities of intravenous perfluorocarbon.

Gut microbiome is associated with the clinical response to anti-PD-1 based immunotherapy in hepatobiliary cancers

BACKGROUND

The gut microbiome is associated with the response to immunotherapy for different cancers. However, the impact of the gut microbiome on hepatobiliary cancers receiving immunotherapy remains unknown. This study aims to investigate the relationship between the gut microbiome and the clinical response to anti-programmed cell death protein 1 (PD-1) immunotherapy in patients with advanced hepatobiliary cancers.

METHODS

Patients with unresectable hepatocellular carcinoma or advanced biliary tract cancers who have progressed from first-line chemotherapy (gemcitabine plus cisplatin) were enrolled. Fresh stool samples were collected before and during anti-PD-1 treatment and analyzed with metagenomic sequencing. Significantly differentially enriched taxa and prognosis associated taxa were identified. The Kyoto Encyclopedia of Genes and Genomes database and MetaCyc database were further applied to annotate the differentially enriched taxa to explore the potential mechanism of the gut microbiome influencing cancer immunotherapy.

RESULTS

In total, 65 patients with advanced hepatobiliary cancers receiving anti-PD-1 treatment were included in this study. Seventy-four taxa were significantly enriched in the clinical benefit response (CBR) group and 40 taxa were significantly enriched in the non-clinical benefit (NCB) group. Among these taxa, patients with higher abundance of Lachnospiraceae bacterium-GAM79 and Alistipes sp Marseille-P5997, which were significantly enriched in the CBR group, achieved longer progression-free survival (PFS) and overall survival (OS) than patients with lower abundance. Higher abundance of Ruminococcus calidus and Erysipelotichaceae bacterium-GAM147 enriched in the CBR group was also observed in patients with better PFS. In contrast, worse PFS and OS were found in patients with higher abundance of Veillonellaceae, which was significantly enriched in the NCB group. Functional annotation indicated that the taxa enriched in the CBR group were associated with energy metabolism while the taxa enriched in the NCB group were associated with amino acid metabolism, which may modulate the clinical response to immunotherapy in hepatobiliary cancers. In addition, immunotherapy-related adverse events were affected by the gut microbiome diversity and relative abundance.

CONCLUSIONS

We demonstrate that the gut microbiome is associated with the clinical response to anti-PD-1 immunotherapy in patients with hepatobiliary cancers. Taxonomic signatures enriched in responders are effective biomarkers to predict the clinical response and survival benefit of immunotherapy, which might provide a new therapeutic target to modulate the response to cancer immunotherapy.

Real-time perfusion imaging with low mechanical index pulse inversion Doppler imaging

OBJECTIVES

We sought to determine how successful pulse inversion Doppler (PID) imaging would be in detecting myocardial perfusion defects during dobutamine stress echocardiography.

BACKGROUND

By transmitting multiple pulses of alternating polarity (PID) at a low mechanical index, myocardial contrast enhancement from intravenously injected microbubbles can be detected using real-time frame rates. Pulse inversion Doppler imaging was performed in 117 patients during dobutamine stress echocardiography by using an intravenous bolus of a perfluorocarbon-filled, albumin-(Optison: n = 98) or liposome- (Definity: n = 19) encapsulated microbubble and a mechanical index of <0.3. The visual identification of myocardial contrast defects and wall motion abnormalities was determined by blinded review. Forty of the patients had quantitative angiography (QA) performed to correlate territorial contrast defects with stenosis diameter >50%.

RESULTS

There was a virtual absence of signal from the myocardium before contrast injections in all patients. Bright myocardial opacification at peak stress was observed in at least one coronary artery territory at frame rates up to 25 Hz in 114 of the 117 patients during dobutamine stress echocardiography. Regional myocardial contrast defects at peak stress were observed in all 30 patients with >50% stenosis in at least one vessel (13 with single-vessel and 17 with multivessel disease). Contrast defects were observed in 17 territories subtended by >50% diameter stenosis that had normal wall motion at peak stress. Overall agreement between QA and myocardial contrast enhancement on a territorial basis was 83%, as compared with 72% for wall motion.

CONCLUSIONS

Pulse inversion Doppler imaging allows the detection of myocardial perfusion abnormalities in real-time during stress echocardiography and will further add to the quality and sensitivity of this test.

Scroll wave dynamics in a three-dimensional cardiac tissue model: roles of restitution, thickness, and fiber rotation

Scroll wave (vortex) breakup is hypothesized to underlie ventricular fibrillation, the leading cause of sudden cardiac death. We simulated scroll wave behaviors in a three-dimensional cardiac tissue model, using phase I of the Luo-Rudy (LR1) action potential model. The effects of action potential duration (APD) restitution, tissue thickness, filament twist, and fiber rotation were studied. We found that APD restitution is the major determinant of scroll wave behavior and that instabilities arising from APD restitution are the main determinants of scroll wave breakup in this cardiac model. We did not see a "thickness-induced instability" in the LR1 model, but a minimum thickness is required for scroll breakup in the presence of fiber rotation. The major effect of fiber rotation is to maintain twist in a scroll wave, promoting filament bending and thus scroll breakup. In addition, fiber rotation induces curvature in the scroll wave, which weakens conduction and further facilitates wave break.

Single-nucleotide polymorphisms in the C-reactive protein (CRP) gene promoter that affect transcription factor binding, alter transcriptional activity, and associate with differences in baseline serum CRP level

To investigate whether functional polymorphisms exist in the C-reactive protein (CRP) gene, i.e., ones that contribute directly to differences in baseline CRP among individuals, we sequenced a 1,156-nucleotide-long stretch of the CRP gene promoter in 287 ostensibly healthy people. We identified two single-nucleotide polymorphisms (SNPs), a bi-allelic one at nucleotide -409 (G-->A), and a tri-allelic one at -390 (C-->T-->A), both resident within the hexameric core of transcription factor binding E-box elements. Electrophoretic mobility shift assays confirmed that the SNP within the sequence (-412)CACGTG(-407) (E-box 1) modulates transcription factor binding, and that the one within (-394)CACTTG(-389) (E-box 2) supports transcription factor binding only when the -390 T allele is present. The commonest of four E-box 1/E-box 2 haplotypes (-409G/-390T) identified in the population supported highest promoter activity in luciferase reporter assays, and the rarest one (-409A/-390T) supported the least. Importantly, serum CRP in people with these haplotypes reproduced this rank order, i.e., people with the -409G/-390T haplotype had the highest baseline serum CRP (mean +/- SEM 10.9 +/- 2.25 microg/ml) and people with the -409A/-390T haplotype had the lowest (5.01 +/- 1.56 microg/ml). Furthermore, haplotype-associated differences in baseline CRP were not due to differences in age, sex, or race, and were still apparent in people with no history of smoking. At least two other SNPs in the CRP promoter lie within E-box elements (-198 C-->T, E-box 4, and -861 T-->C, E-box 3), indicating that not only is the quality of E-box sites in CRP a major determinant of baseline CRP level, but also that the number of E-boxes may be important. These data confirm that the CRP promoter does encode functional polymorphisms, which should be considered when baseline CRP is being used as an indicator of clinical outcome. Ultimately, development of genetic tests to screen for CRP expression variants could allow categorization of healthy people into groups at high versus low future risk of inflammatory disease.

Role of papillary muscle in the generation and maintenance of reentry during ventricular tachycardia and fibrillation in isolated swine right ventricle

BACKGROUND

The role of papillary muscle (PM) in the generation and maintenance of reentry is unclear.

METHODS AND RESULTS

Computerized mapping (477 bipolar electrodes, 1.6-mm resolution) was performed in fibrillating right ventricles (RVs) of swine in vitro. During ventricular fibrillation (VF), reentrant wave fronts often transiently anchored to the PM. Tissue mass reduction was then performed in 10 RVs until VF converted to ventricular tachycardia (VT). In an additional 6 RVs, procainamide infusion converted VF to VT. Maps showed that 77% (34 of 44) of all VT episodes were associated with a single reentrant wave front anchored to the PM. Purkinje fiber potentials preceded the local myocardial activation, and these potentials were recorded mostly around the PM. When PM was trimmed to the level of endocardium (n = 4), sustained VT was no longer inducible. Transmembrane potential recordings (n = 5) at the PM revealed full action potential during pacing, without evidence of ischemia. Computer simulation studies confirmed the role of PM as a spiral wave anchoring site that stabilized wave conduction.

CONCLUSIONS

We conclude that PM is important in the generation and maintenance of reentry during VT and VF.

Neurofilament proteins in neurodegenerative diseases

The function of neurofilaments, the major component in large myelinated neurons, is not well understood even though they were discovered as structures over 100 years ago. Recent studies have suggested that neuro-filaments are closely related to many neurodegenerative diseases, such as amyotrophic lateral sclerosis, Parkinson disease Alzheimer disease, and diabetes. Using in vitro assays, cultures and transgenic mice, these studies provided new insights into neurofilament function. The function of each subunit, the relationship of neurofilaments with other cytoskeletal elements and their clinical significance are topics of increasing attention.

Efficacy of nisin in treatment of clinical mastitis in lactating dairy cows

Nisin is an antimicrobial polypeptide produced by Lactococcus lactis and is believed nontoxic to humans. The objective of this study was to evaluate a nisin-based formulation for the treatment of bovine clinical mastitis in lactating dairy cattle. A total of 92 cows with 107 clinically mastitic quarters were randomly assigned to nisin- (48 cows with 51 quarters) and gentamicin (GM)-treated (44 cows with 56 quarters) groups. In the nisin-treated group, cows received an intramammary infusion of nisin at a dose of 2,500,000 IU; in the GM-treated group, intramammary infusion of GM was administered at a dose of 0.8 g. Results indicated that nisin offered a clinical cure rate similar to GM (90.2 vs. 91.1%) and no difference in bacteriological cure rate than GM-treated group (60.8 vs. 44.6%, respectively). Proportion of the quarters with milk somatic cell counts <500,000 cells/mL was not different in the nisin-treated group (50.0 and 47.8%) compared with the GM-treated group (33.3 and 37.3%) 1 and 2 wk after treatment. Of 17 Staphylococcus aureus isolates, 82.5% were resistant to penicillin, and 35.3% to GM, but none of them to nisin. Nisin therapy eliminated 54.5% (6 of 11) of S. aureus IMI, whereas GM eliminated 33.3% (2 of 6). Nisin in milk (4.5 +/- 0.8 IU/mL) was detected only at 12 h following intramammary infusion, which was much lower than the upper limit (500 mg/mL) allowed as preservative in milk by the China authority. Because of its efficacy in the treatment of bovine clinical mastitis, especially resistant Staph. aureus-caused IMI, as well as its safety in humans, nisin deserves further study to clarify its effects on mastitis caused by different mastitis pathogens on a larger scale.

Estrogen protection against bone resorbing effects of parathyroid hormone infusion. Assessment by use of biochemical markers

OBJECTIVE

Because parathyroid hormone (PTH) stimulates bone resorption, resistance to its actions might help maintain bone mass. We tested the hypothesis that the effects of estrogen on bone are accomplished in part by decreasing the sensitivity of the skeleton to the resorbing effects of PTH.

STUDY DESIGN

Comparison of response to PTH infusion in untreated and estrogen-treated postmenopausal women with osteoporosis.

INTERVENTION

(1-34) human PTH, 0.55 U/(kg.h), was infused intravenously over 20 hours.

SETTING

The inpatient clinical research unit of a referral hospital.

PATIENTS

Women with primary postmenopausal osteoporosis who were untreated (n = 15) or treated with estrogen (n = 17).

MAIN OUTCOME MEASURES

Skeletal turnover indices including hydroxyproline, deoxypyridinoline, pyridinoline, tartrate-resistant acid phosphatase, alkaline phosphatase, bone Gla protein, and insulin-like growth factor-1.

RESULTS

All basal indices were higher in untreated than in estrogen-treated women, but statistical differences were seen only for deoxypyridinoline and pyridinoline. During the 20-hour infusion, hydroxyproline/creatinine increased 0.023 mumol/mumol in untreated women but only 0.010 mumol/mumol in estrogen-treated women (P < 0.05). Corresponding changes for deoxypyridinoline/creatinine were 14.6 mumol/mumol and 3.5 mumol/mumol (P = 0.06). Tartrate-resistant acid phosphatase and pyridinoline increased only in untreated group. A circadian rhythm in circulating bone Gla protein was seen in both groups without clear PTH-induced effects or differences between groups. Alkaline phosphatase levels decreased and insulin-like growth factor-1 levels increased in both groups with no distinction between untreated and estrogen-treated women [corrected].

CONCLUSION

The estrogenized postmenopausal osteoporotic skeleton is less sensitive to the bone resorbing effects of acutely administered PTH. There are no differential effects on bone formation.

Real-time assessment of myocardial perfusion and wall motion during bicycle and treadmill exercise echocardiography: comparison with single photon emission computed tomography

OBJECTIVES

We sought to determine the feasibility and accuracy of real-time imaging of myocardial contrast echocardiography (MCE) in detecting myocardial perfusion defects during exercise echocardiography compared with radionuclide tomography.

BACKGROUND

Ultrasound imaging at a low mechanical index and frame rate (10 to 20 Hz) after intravenous injections of perfluorocarbon containing microbubbles has the potential to evaluate myocardial perfusion and wall motion (WVM) simultaneously and in real time.

METHODS

One hundred consecutive patients with intermediate-to-high probability of coronary artery disease underwent treadmill (n = 50) or supine bicycle (n = 50) exercise echocardiography. Segmental perfusion with MCE and WM w ere assessed in real time before and at peak exercise using low mechanical index (0.3) and frame rates of 10 to 20 Hz after 0.3 ml bolus injections of intravenous Optison (Mallinckrodt Inc., San Diego, California). All patients had a dual isotope (rest thallium-201, stress sestamibi) study performed during the same exercise session, and 44 patients had subsequent quantitative coronary angiography.

RESULTS

In the 100 patients, agreement between MCE and single photon emission computed tomography (SPECT) was 76%, while it was 88% between MCE and WM assessment. Compared with quantitative angiography, sensitivity of MCE, SPECT and WM was comparable (75%), with a specificity ranging from 81% to 100%. The combination of MCE and WM had the best balance between sensitivity and specificity (86% and 88%,respectively) with the highest accuracy (86%).

CONCLUSIONS

The real-time assessment of myocardial perfusion during exercise stress echocardiography can be achieved with imaging at low mechanical index and frame rates. The combination of WM and MCE correlates well with SPECT and is a promising important addition to conventional stress echocardiography.

Pembrolizumab combined with lenvatinib as non-first-line therapy in patients with refractory biliary tract carcinoma

BACKGROUND

A therapeutic strategy involving combined treatment with lenvatinib plus pembrolizumab (LEP) has demonstrated a relatively high antitumor response in several solid tumors; however, the efficacy and safety of LEP in patients with refractory bile tract carcinoma (BTC) remains unknown.

METHODS

This is a single-arm study for a preliminary assessment of the efficacy and tolerability of LEP in patients who experienced progression from prior systemic treatments. Pre-treatment tumor tissues were collected to retrospectively evaluate the expression status of PDL1.

RESULTS

Thirty-two patients received second-line and above treatment with LEP. Overall, the objective response rate (ORR) was 25%, the disease control rate (DCR) was 78.1%, and the clinical benefit rate (CBR) was 40.5%. The median progression-free survival (PFS) was 4.9 months (95% CI: 4.7-5.2 months), and the median overall survival (OS) was 11.0 months (95% CI: 9.6-12.3 months). For tolerability, no grade 5 serious adverse events (AEs) were reported. All patients had any-grade AEs, and 59.3% of the patients experienced grade 3 AEs, while only 1 patient experienced a grade 4 AE of stomach bleeding. Fatigue was the most common AE, followed by hypertension and elevated aminotransferase levels. Retrospective analysis for PDL1 expression revealed that PDL1 positive tumor cells were associated with improved clinical benefits and survival outcomes.

CONCLUSIONS

LEP is a promising alternative as a non-first-line therapeutic regimen for patients with refractory BTC. Furthermore, well-designed prospective clinical trials with a control arm are still needed to obtain more evidences to confirm the efficacy and safety of this particular regimen as well as the role of PDL1 expression.

Origins of spiral wave meander and breakup in a two-dimensional cardiac tissue model

We studied the stability of spiral waves in homogeneous two-dimensional cardiac tissue using phase I of the Luo-Rudy ventricular action potential model. By changing the conductance and the relaxation time constants of the ion channels, various spiral wave phenotypes, including stable, quasiperiodically meandering, chaotically meandering, and breakup were observed. Stable and quasiperiodically meandering spiral waves occurred when the slope of action potential duration (APD) restitution was < 1 over all diastolic intervals visited during reentry; chaotic meander and spiral wave breakup occurred when the slope of APD restitution exceeded 1. Curvature of the wave changes both conduction velocity and APD, and their restitution properties, thereby modulating local stability in a spiral wave, resulting in distinct spiral wave phenotypes. In the LRI model, quasiperiodic meander is most sensitive to the Na+ current, whereas chaotic meander and breakup are more dependent on the Ca2+ and K+ currents.

Improved endocardial border resolution during dobutamine stress echocardiography with intravenous sonicated dextrose albumin

OBJECTIVES

The purpose of this study was to determine whether intravenous sonicated dextrose albumin could improve endocardial border resolution during dobutamine stress echocardiography.

BACKGROUND

Sonicated albumin improves endocardial border resolution in patients undergoing exercise stress echocardiography. Because a sonicated mixture of albumin with dextrose results in better transpulmonary passage than sonicated albumin alone, this agent could be utilized to further improve endocardial border resolution during dobutamine stress echocardiography.

METHODS

We gave intravenous injections of sonicated dextrose and albumin to 50 patients undergoing dobutamine stress echocardiography. Left ventricular video intensity, contrast agent persistence (in seconds), number of contrast agent-enhanced cardiac cycles and improvement in endocardial border resolution were assessed from the apical four-chamber view at baseline, low dose (10 micrograms/kg body weight per min) and peak dobutamine infusion.

RESULTS

There was significantly better left ventricular peak video intensity at peak dobutamine infusion than after the same injection at baseline (p < 0.005, analysis of variance). The number of contrast agent-enhanced cardiac cycles in the left ventricular cavity was also significantly longer at peak infusion. Endocardial border resolution was improved (mainly in lateral segments) in 93% of patients at low dose and 95% of patients at peak infusion.

CONCLUSIONS

Intravenous sonicated dextrose albumin improves endocardial border resolution during dobutamine stress echocardiography.

Thrombolytic enhancement with perfluorocarbon-exposed sonicated dextrose albumin microbubbles

Whereas low-intensity, high-frequency ultrasound (US) alone appears to cause minimal thrombolysis, US combined with air-filled microbubbles does increase the amount of urokinase (UK)-mediated clot lysis (CL). Because this phenomenon may be mediated by cavitation-induced streaming, we hypothesized that perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles, which are more stable than air-filled microbubbles, may also enhance US-induced thrombolysis. We measured the percentage CL of equally sized thrombi (1.0 +/- 0.1 mg) made from freshly drawn blood incubated for 2 hours and then exposed to 20 kHz US (0.846 MPa peak negative pressure). The thrombi were bathed in 4 ml of saline solution, UK alone (20,000 U), PESDA alone, or a combination of PESDA with UK. The percentage CL achieved with PESDA and therapeutic US was also compared with the percentage CL achieved with room air-filled sonicated dextrose albumin (RASDA) microbubbles. When compared with US alone (24% +/- 13% CL) or UK alone (17% +/- 3% CL), PESDA plus US produced significantly better CL (43% +/- 17%; p< 0.05). PESDA combined with US also produced significantly greater CL than RASDA combined with US (28% +/- 9%; p < 0.05). The optimal CL was achieved with a combination of PESDA with UK with US (60% +/- 14% CL). We conclude that PESDA microbubbles alone may be capable of inducing thrombolysis when insonified with a low-frequency transducer.

A prospective, randomized, comparative US trial of a combination hepatitis A and B vaccine (Twinrix) with corresponding monovalent vaccines (Havrix and Engerix-B) in adults

In an open, randomized, multicenter, controlled clinical trial in the US, 773 adults were administered either a combination hepatitis vaccine (Twinrix: 720 EL.U inactivated hepatitis A antigen and 20 mcg recombinant hepatitis B surface antigen per milliliter) on a 0, 1, 6 month schedule or corresponding monovalent vaccines concurrently (Havrix, 1440 EL.U/ml of hepatitis A antigen at 0, 6 months and Engerix-B, 20 mcg of hepatitis B surface antigen at 0, 1, 6 months). Non-inferiority testing for the primary endpoint, severe soreness, and equivalence testing for the secondary endpoints, anti-HAV seroconversion and anti-HBs seroprotection, showed that safety and immunogenicity were comparable in the two groups.

Cross-cultural adaptation and validation of Singapore English and Chinese versions of the Knee injury and Osteoarthritis Outcome Score (KOOS) in Asians with knee osteoarthritis in Singapore

OBJECTIVE

To cross-culturally adapt and validate Singapore English and Chinese versions of the Knee injury and Osteoarthritis Outcome Score (KOOS) in patients with knee osteoarthritis (OA) in Singapore.

METHODS

Singapore English and Chinese versions were cross-culturally adapted from the source English KOOS following standard guidelines (including cognitive debriefing). Patients were asked to complete identical questionnaires containing the KOOS, Short Form 36 Health Survey, and EQ-5D twice within 6 days. Reliability was assessed using Cronbach's alpha and intraclass correlation coefficients (ICC), dimensionality using item-to-domain correlations and convergent and divergent construct validity using 14 and 13 a priori hypotheses, respectively.

RESULTS

Singapore English and Chinese KOOS versions were well accepted by patients in pilot testing and were therefore administered to a consecutive sample of 127 English and 131 Chinese-speaking Singaporeans with knee OA. Cronbach's alpha exceeded 0.7 for all domains except for Chinese pain and symptoms domains. ICC exceeded 0.7 for all domains except for English sport and recreation and Chinese knee-related QoL domains. Hypothesized item-to-domain correlations (Spearman's rho>or=0.4) were observed for 38 items in English and 29 in Chinese versions. Convergent construct validity was supported by the presence of hypothesized moderate/strong correlations (rho=0.37-0.65) for 13 and 11 a priori hypotheses in the English and Chinese KOOS, respectively. Divergent construct validity was supported by the presence of weak correlations (rho=0.02-0.34) for 12 and 11 a priori hypotheses in the English and Chinese KOOS, respectively.

CONCLUSION

The Singapore English and Chinese KOOS were well accepted and demonstrated acceptable reliability and validity in Asian patients with knee OA in Singapore.

Intravascular ultrasound study of angiographically mildly diseased coronary arteries

OBJECTIVES

We hypothesized that intravascular ultrasound may identify significant coronary artery narrowing in the mildly diseased coronary artery of patients with insignificant or one- or two-vessel coronary artery disease.

BACKGROUND

Necropsy studies have revealed that coronary angiography may underestimate stenosis severity in vessels that appear mildly diseased. Intravascular ultrasound has been shown to detect atherosclerotic changes in angiographically normal coronary arteries and to correlate better with histologic findings.

METHODS

In 20 patients, we performed intravascular ultrasound imaging (3.5F catheter, 30-MHz transducer) in 37 coronary arteries that were considered mildly diseased (<50% diameter narrowing) by qualitative angiography. The angiographic diagnosis was no significant coronary artery disease in eight patients, one-vessel disease in seven and two-vessel disease in five. Each vessel, except for the left main coronary artery, was divided into proximal, mid and distal segments. Percent area narrowing and minimal lumen diameter were subsequently quantified by both ultrasound and quantitative angiography.

RESULTS

Mean maximal arterial area narrowing by ultrasound in the 67 segments studied was 36 +/- 20% (range 0% to 80.2%) and 19 +/- 23% (range 0% to 82%) by quantitative angiography of these same segments (p < 0.001, paired t test). Mean minimal lumen diameter of the segment was 3.3 +/- 0.9 mm by ultrasound and 2.7 +/- 0.8 mm by quantitative angiography. In 10 patients there were 19 angiographically mildly diseased segments where the percent arterial area narrowing by ultrasound was > or = 50%. Intravascular ultrasound revealed that the more proximal (reference) segment had > 25% intimal thickening in 12 of the 19 underestimated segments. In six stenosed segments (32%), total vessel area increased compared with that of the adjacent proximal vessel segment because of compensatory dilation.

CONCLUSIONS

Intravascular ultrasound identifies potentially significant coronary artery disease in vessels that appear to be only mildly diseased by angiography.

Significance of Tumor Mutation Burden in Immune Infiltration and Prognosis in Cutaneous Melanoma

Background: Melanoma is highly immunogenic and therefore suitable for immunotherapy, but the efficacy is limited by response rate. In several types of tumor, tumor mutation burden (TMB) and immune infiltration have been reported to predict the response to immunotherapy, although each has its limitations. In the current study, we aimed to explore the association of TMB with immune infiltration and prognosis in cutaneous melanoma. Methods: The data of cutaneous melanoma used for analyses was downloaded from The Cancer Genome Atlas (TCGA) database. The mutation data was sorted using "maftools" R package. TMB was estimated and then patients were divided into two groups based on TMB. The association of TMB with prognosis and clinical characteristics was explored. Differential analysis between two TMB groups was performed using "DESeq2" R package to identify differentially expressed genes (DEGs). The function enrichment analyses of DEGs were conducted to screen critical pathways. Besides, DEGs were further filtered to identify two hub genes, based on which a risk score model and nomogram for predicting prognosis were conducted, and the validation was performed using three datasets from Gene Expression Omnibus (GEO) database. Finally, CIBERSORT algorithm and TIMER database were used to assess the effect of TMB and hub genes on immune infiltration. Results: The most common mutation was C > T, and the top three frequently mutated genes were TTN, MUC16, and BRAF. Higher TMB indicated better survival outcomes and lower pathological stages. 735 DEGs were identified and mainly involved in immune-related and adhesion-related pathways. The risk score model and nomogram were validated using receiver operating characteristic (ROC) curves and calibration curves, and exhibited relatively high predictive capability. Decision curve analysis (DCA) was used to assess clinical benefit. As for immune infiltration, the proportion was higher for macrophages M1 and M2 in the high-TMB group, while lower for memory B cells and regulatory T cells. Conclusions: In cutaneous melanoma, TMB was positively correlated with prognosis. The risk score model and nomogram can be conveniently used to predict prognosis. The association of TMB with immune infiltration can help improve the predicting methods for the response to immunotherapy.

A prospective genome-wide study of prostate cancer metastases reveals association of wnt pathway activation and increased cell cycle proliferation with primary resistance to abiraterone acetate-prednisone

Background

Genomic aberrations have been identified in metastatic castration-resistant prostate cancer (mCRPC), but molecular predictors of resistance to abiraterone acetate/prednisone (AA/P) treatment are not known.

Patients and methods

In a prospective clinical trial, mCRPC patients underwent whole-exome sequencing (n = 82) and RNA sequencing (n = 75) of metastatic biopsies before initiating AA/P with the objective of identifying genomic alterations associated with resistance to AA/P. Primary resistance was determined at 12 weeks of treatment using criteria for progression that included serum prostate-specific antigen measurement, bone and computerized tomography imaging and symptom assessments. Acquired resistance was determined using the end point of time to treatment change (TTTC), defined as time from enrollment until change in treatment from progressive disease. Associations of genomic and transcriptomic alterations with primary resistance were determined using logistic regression, Fisher's exact test, single and multivariate analyses. Cox regression models were utilized for determining association of genomic and transcriptomic alterations with TTTC.

Results

At 12 weeks, 32 patients in the cohort had progressed (nonresponders). Median study follow-up was 32.1 months by which time 58 patients had switched treatments due to progression. Median TTTC was 10.1 months (interquartile range: 4.4-24.1). Genes in the Wnt/β-catenin pathway were more frequently mutated and negative regulators of Wnt/β-catenin signaling were more frequently deleted or displayed reduced mRNA expression in nonresponders. Additionally, mRNA expression of cell cycle regulatory genes was increased in nonresponders. In multivariate models, increased cell cycle proliferation scores (≥ 50) were associated with shorter TTTC (hazard ratio = 2.11, 95% confidence interval: 1.17-3.80; P = 0.01).

Conclusions

Wnt/β-catenin pathway activation and increased cell cycle progression scores can serve as molecular markers for predicting resistance to AA/P therapy.

Noninvasive identification of acute myocardial ischemia and reperfusion with contrast ultrasound using intravenous perfluoropropane-exposed sonicated dextrose albumin

OBJECTIVES

The purpose of this study was to determine whether intravenous dextrose albumin sonicated with a commonly used gas of low blood solubility and diffusivity (perfluoropropane) could identify acute myocardial ischemia and reperfusion.

BACKGROUND

Recently, it has been demonstrated that dextrose albumin sonicated with gases that have low blood solubility and diffusivity results in microbubbles capable of consistently producing myocardial ultrasound contrast after intravenous injection. It remains to be determined, however, whether this contrast agent can visually detect the myocardial blood flow abnormalities seen with acute ischemia or stunned myocardium after reperfusion.

METHODS

We gave intravenous injections (0.06 ml/kg body weight) of perfluoropropane-exposed sonicated dextrose albumin to 10 open chest dogs. The measured degree of myocardial contrast (0+ to 2+) and background-subtracted peak anterior myocardial videointensity produced from each injection were measured at three stages: 1) under baseline conditions, 2) during acute ischemia produced by a proximal left anterior descending coronary artery ligation lasting 10 to 120 min, and 3) after reflow was established. Coronary blood flow was monitored during all injections by using an ultrasound flow probe placed around the left anterior descending artery.

RESULTS

Coronary blood flow ranged from 0 to 137 ml/min, and peak myocardial videointensity after intravenous administration of perfluoropropane-exposed sonicated dextrose albumin ranged from 0 to 70 gray scale U. There was consistent visual myocardial opacification in all dogs during baseline conditions and a visually evident decrease in myocardial contrast in the left anterior descending artery distribution after ligation. A relative increase in contrast in this same distribution after intravenous contrast agent administration occurred in 7 of the 10 dogs during reflow. Quantitatively, there was an excellent correlation in individual dogs between peak myocardial videointensity and coronary flow at all stages (mean correlation coefficient 0.95 +/- 0.04, range 0.87 to 0.99).

CONCLUSIONS

Perfluoropropane-exposed sonicated dextrose albumin is an ultrasound contrast agent that can visually identify myocardial perfusion abnormalities from a peripheral venous injection.

Role of pectinate muscle bundles in the generation and maintenance of intra-atrial reentry: potential implications for the mechanism of conversion between atrial fibrillation and atrial flutter

To determine the role of pectinate muscle (PM) bundles in the formation of intra-atrial reentry, 10 isolated canine right atrial tissues were perfused with Tyrode's solution containing 1 to 2.5 micromol/L acetylcholine (ACh). The endocardium was mapped using 477 bipolar electrodes with 1.6-mm resolution. Reentry was induced by a premature stimulus (S2). Computer simulation studies were used to investigate the importance of regional myocardial thickness in reentry formation. A total of 40 episodes of reentry were induced; 28 episodes were stationary, and the remaining 12 were nonstationary. The stationary reentry was induced either immediately after the S2 stimuli (n=9) or after an initial period of irregular activations that lasted 1460+/-1077 ms (n= 19). Of 28 episodes, 20 were initiated by conduction block along large PM ridges, leading to wave break and the initiation of reentry. The reentrant wave fronts remained stationary and rotated around these ridges as anchoring sites. During the transition from the initial irregular activations to stationary reentry, the electrogram morphology converted from "fibrillation-like" to "flutter-like" activity. In 8 episodes, initially stationary reentry converted to irregular activations because of interference with outside wave fronts (n=5) or spontaneous separation of waves from the ridges (n=3). Compared with stationary reentry, nonstationary reentry always occurred over an area without large PMs, and the mean life span was much shorter (102+/-151 versus 3.8+/-1.1 rotations, P<0.001). Computer simulation studies showed that a critical ridge thickness is needed for reentry to anchor, thereby converting fibrillation to flutter. We conclude that PM ridge forms an area where wave break occurs, allowing the initiation of reentry. It also provides a natural anchor to the reentrant wave front, lengthening the life span of reentry. The attachment and detachment of the reentrant wave front to and from the ridge determine "flutter-like" or "fibrillation-like" activity.

Inactivation of the mouse adenylyl cyclase 3 gene disrupts male fertility and spermatozoon function

Mammalian spermatids and spermatozoa express functional G protein-coupled receptors. However, bicarbonate-regulated soluble adenylyl cyclase (AC), the major AC present in these cells, is not directly coupled to G proteins. To understand how G protein-coupled receptors signal in spermatozoa, we investigated whether a conventional transmembrane cyclase is present and biologically active in these cells. Here, we provide evidence for expression of type 3 AC (AC3) in male germ cells and describe the effects of disruption of the AC3 gene on fertility and function of mouse spermatozoa. As previously reported in rat, AC3 mRNA is expressed in mouse testes and localized, together with soluble AC mRNA, mainly in postmeiotic germ cells. AC3 protein was detected by immunolocalization in round and elongating spermatids in a region corresponding to the developing acrosome and was retained in the mature spermatozoa of the epididymis. Forskolin caused a small increase in cAMP production in mouse spermatozoa, but this increase could not be detected in the AC3(-/-) mice. Inactivation of the AC3 gene did not have overt effects on spermatogenesis; however, AC3(-/-) males were subfertile with only three litters generated by 11 males over a period of 6 months. When used in in vitro fertilization, spermatozoa from these AC3(-/-) mice produced few embryos, but their fertilizing ability was restored after removal of the zona pellucida. Despite an apparently normal structure, these spermatozoa had decreased motility and showed an increase in spontaneous acrosome reactions. These data support the hypothesis that AC3 is required for normal spermatid or spermatozoa function and male fertility.

Electrophysiological heterogeneity and stability of reentry in simulated cardiac tissue

Generation of wave break is a characteristic feature of cardiac fibrillation. In this study, we investigated how dynamic factors and fixed electrophysiological heterogeneity interact to promote wave break in simulated two-dimensional cardiac tissue, by using the Luo-Rudy (LR1) ventricular action potential model. The degree of dynamic instability of the action potential model was controlled by varying the maximal amplitude of the slow inward Ca(2+) current to produce spiral waves in homogeneous tissue that were either nearly stable, meandering, hypermeandering, or in breakup regimes. Fixed electrophysiological heterogeneity was modeled by randomly varying action potential duration over different spatial scales to create dispersion of refractoriness. We found that the degree of dispersion of refractoriness required to induce wave break decreased markedly as dynamic instability of the cardiac model increased. These findings suggest that reducing the dynamic instability of cardiac cells by interventions, such as decreasing the steepness of action potential duration restitution, may still have merit as an antifibrillatory strategy.