Li isotopic seasonality in a small catchment at the northeastern Tibetan Plateau: Roles of hydrology and temperature dependency

Silicate weathering is critical to sustain our habitable planet. Lithium (Li) isotopes enable us to investigate the nature of silicate weathering. A number of riverine Li isotope (δ⁷Li_rw) investigations have been made from polar to equatorial terrains, but there remains no consensus about the controlling mechanisms of both weathering and δ⁷Li_rw. Here we investigated δ⁷Li_rw response to climate by collecting weekly river water samples in a small catchment (the Buha River within the Lake Qinghai basin) on the northeastern Tibetan Plateau, with stable tectonic, lithology, and topography. In the hydrology year of 2007 of the Buha River, we find that during the dry seasons, δ⁷Li_rw ratios show temperature dependency typically, when the groundwater fed the river. During the monsoon seasons, δ⁷Li_rw were obviously lower than the temperature dependency predicted values, when abundant rock dissolved and thereby fresh Li release into rivers. We propose that the hydrology and temperature dependency together play important roles in regulating δ⁷Li_rw ratios in such an alpine small catchment. The mechanism is that long residence time facilitates the equilibrium chemical and Li isotopic fractionation during the dry seasons, so a temperature dependency of δ⁷Li_rw is achieved. In contrast, rapid erosion and weathering contribution of fresh rock-like δ⁷Li to river water would significantly decrease δ⁷Li_rw ratios during the monsoon seasons. This hypothesis can better interpret previously reported data of seasonal δ⁷Li_rw variation, as a superposition between temperature dependency and hydrology regulation on silicates weathering in the small catchments besides tectonics.

Molecular characterization and clinical outcomes in EGFR-mutant de novo MET-overexpressed advanced non-small-cell lung cancer

Background

Approximately 2%-8% of non-small-cell lung cancer (NSCLC) harbors concurrent epidermal growth factor receptor (EGFR) sensitizing mutation and mesenchymal–epithelial transition factor (MET) amplification prior to EGFR-tyrosine kinase inhibitor (EGFR-TKI) therapy. This study aimed to investigate the optimal first-line therapeutic options for patients with concurrent EGFR-mutant, MET-overexpressed/amplified advanced NSCLC.

Methods

A total of 104 treatment-naïve patients with EGFR-mutant de novo MET-overexpressed advanced NSCLC were identified using immunohistochemistry and stratified to four groups according to treatment regimen: EGFR-TKI monotherapy (n = 48), EGFR-TKI combined with either crizotinib (n = 9) or chemotherapy (n = 12), and chemotherapy (n = 35). A subpopulation of 28 patients was also tested with next-generation sequencing (NGS). Objective response rate (ORR) and progression-free survival (PFS) outcomes were analyzed according to treatment strategies and molecular features.

Results

All the patients (n = 104) achieved ORR of 36.5% and median PFS (mPFS) of 7.0 months. Baseline clinicopathologic characteristics were similar among the four treatment groups. Compared with chemotherapy, EGFR-TKI monotherapy or EGFR-TKI combination therapy achieved significantly higher ORR (P < 0.001) and longer mPFS (P = 0.003). No ORR or PFS difference was observed between EGFR-TKI monotherapy and combination therapy. In the NGS-identified population (n = 28), patients who received EGFR-TKI plus crizotinib (n = 9) achieved similar ORR (88.9% versus 57.9%, P = 0.195) and mPFS (9.0 versus 8.5 months, hazard ratio 1.10, 95% confidence interval 0.43-2.55, P = 0.45) than those who received EGFR-TKI monotherapy (n = 19), regardless of MET copy number status. Grade 3/4 rashes were significantly more among patients who received EGFR-TKI plus crizotinib (P = 0.026).

Conclusions

Our findings provided clinical evidence that patients with concurrent EGFR sensitizing mutation and de novo MET amplification/overexpression could benefit from first-line EGFR-TKI monotherapy.

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Concomitant EGFR sensitizing mutation and MET overexpression/amplification were detected in 2.6% of lung cancer patients.

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EGFR-TKI monotherapy elicited a higher response rate and longer PFS than chemotherapy.

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EGFR-TKI with or without crizotinib elicited comparable PFS regardless of MET copy number.

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EGFR-TKI monotherapy achieved lower number of grade 3/4 adverse events than EGFR-TKI plus crizotinib.

Advances in Neuropathologic Research of Hypoglycemic Brain Damage Caused by Insulin Overdose

Abstract

The number of death from insulin overdose, including accidental poisoning, suicide and homicide, is increasing these years. The forensic diagnosis of death from insulin overdose is a tough task. Glucose is the main energy source of the brain. Therefore, hypoglycemic brain damage is considered to be the main reason of death from insulin overdose. Recently, research of hypoglycemic brain damage caused by insulin overdose is gradually being paid attention in the field of forensic medicine. This paper summarizes the neuropathologic changes, pathophysiologic process and potential neural molecular markers of hypoglycemic brain damage caused by insulin overdose in terms of forensic neuropathology, providing reference for the research and practice in forensic medicine related fields.

Analysis of 4 Cases of Electrocution due to Direct Current Electronic Hunter

Abstract

Objective To summarize the characteristics of cases of electrocution due to direct current （DC） electronic hunter, and to provide references for forensic identification. Methods Four cases of electrocution due to DC electronic hunter were collected. Statistical analysis was carried out from the perspective of the scene and electric marks distribution, damage characteristics and histopathological changes. Results All the 4 cases of electrocution were accidental events. There were multiple electric marks, most of which were located in the lower limbs with serious damage. Some strip type electric marks were visible. Conclusion The distribution, morphological characteristics and severity of the electric marks caused by DC electronic hunter are different from those of the ordinary low-voltage alternating current damage. It is alerting that there would be actions of destroying the scene and abandoning the corpse in such cases.

Abstract P2-14-18: Achiveing rapid intrao-operative diagnosis during breast cancer surgery using high-reloution full-field optical coherence imaging and dynamic cell imaging

Background: Intraoperative pathological diagnosis such as frozen section and imprint cytology is not routinely recommended in clinical practice because of time and accuracy concerns. Full-field optical coherence tomography (FF-OCT) is a new optical imaging technique that could generate sectioning tomogram from fresh tissue and provide depiction of the morphological structure and pathological changes in minutes without conventional tissue preparation, slicing, and staining, and dynamic cell imaging (DCI) added the viability information of cells/tissue, which could be more important in cancer diagnosis. This study was to evaluate the feasibility and diagnostic value of FF-OCT and DCI in breast lesions and lymph node specimens during breast cancer surgery.

Methods: We evaluated normal breast tissue, benign breast lesions, breast cancer and axillary lymph node specimens from 107 patients using FF-OCT and DCI. After the optical assessment, the tissue was paraffin embedded and sent to conventional H&E diagnosis. The similar layer of OCT and H&E images were compared and diagnostic criteria were generated. The diagnostic sensitivity and specificity by two trained surgeons without pathology diagnosis experience were evaluated.

Results: A total of 194 specimens were examined, including 143 breast tissue(101 malignant and 42 benign/normal) and 51 lymph nodes(26 metastatic and 25 non-metastatic). On FF-OCT and DCI, normal morphological structures such as adipose, collagen, mammary ducts, and lobules in breast tissue and lymphoid follicle and hilum in lymph nodes were easily recognized. Breast cancer characteristics on H&E imaging correspond to collagen distortion, focal hypointensity, micro-calcification, clustered or linear lively cells et etc on FF-OCT or DCI, which could also be easily distinguished. We included the previously mentioned features to build diagnosis criteria for cancer on FF-OCT and DCI. The average acquisition time is 14±11 minutes. The sensitivity and specificity for breast cancer diagnosis were 92.1% and 94.3% respectively. The sensitivity and specificity for lymph node involvement were 92.3% and 84% respectively.

Conclusion: The time- and tissue-saving optical imaging technique yielded high accuracy that was comparable to that of traditional intraoperative and postoperative pathological diagnosis in breast cancer and lymph node metastasis. These results implied the promising application in the intraoperative evaluation and possible decrease of the re-excision rate for breast cancer surgery.

Citation Format: Yang H, Zhang S, Guo J, Xie F, Tong F, Cao Y, Liu P, Zhou B, Cheng L, Liu M, Wang S, Peng Y, Wang C, Yang Y, Ma Y, Chen D, Shen D, Wang S. Achiveing rapid intrao-operative diagnosis during breast cancer surgery using high-reloution full-field optical coherence imaging and dynamic cell imaging [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-18.

Abstract P3-03-43: Incorporation of MSKCC nomogram to guide the application of intra-operative sentinel lymph node frozen section evaluation in patients with early breast cancer

Background and Objectives:

Although de-escalation of axillary surgery becomes more popular, axillary lymph node dissection (ALND) is still the standard care for sentinel lymph node(SLN) positive patients not meeting the criteria of ACOSOG Z0011 in many hospitals, and frozen section (FS) of SLN is one of the valuble intra-operative assesments to avoid axilla re-operation although it was controversial due to accuracy and efficiency concerns. This study was to assess the performance of selective use of frozen section evaluation guided by MSKCC lymph node metastasis risk prediction nomogram to optimize the proceudure to be more accurate and cost effective.

Methods:

Surgical pathology records of consecutive 2582 biopsies in 2552 patients breast cancer patients from 2011 to 2017 were reviewed, intra-operative frozen section diagnosis were compared to post-operative paraffin reports. We calculated the sensitivity, specificity, accuracy and FNR for different MSKCC risk, the axilla re-operation rate with or without FS and the number needed to treat (NNT) to avoid second ALND was also analyzed.

Results:

The sensitivity, specificity, and FNR of FS were 84.7%, 99.9%, and 15.3% respectively. The axilla re-operation rates were significantly decreased if FS was done(4.7%±0.4% with FS versus 35.8%±5.8% without FS, P&lt;0.001). The estimated axilla re-operation rate without FS was positively correlated with MSKCC risk(r=0.99, P&lt;0.001), while NNT to avoid second ALND by FS were negatively correlated with MSKCC risk(r=-0.98, P&lt;0.001). When patients were divided into four groups according to quartile MSKCC risk, the axilla re-excisional rates were 18.4%, 25.1%, 38.7%, 58.7% without FS, while 4.8%, 3.2%, 5.6%, 3.2% with FS, and NNT correspondingly decreased from 7.3, 4.5, 3.0 to 1.8. An decision-making algorithm for application of FS was proposed.

Conclusion:

Stratified decision-making algorithm based on MSKCC prediction model improved the efficiency of FS to avoid axilla re-operatioin in patients undergoing sentinel lymph node biopsy. We recommend FS be restricted to patients with MSKCC risk higher than 0.5 who do not meet ACOSOG Z0011 criteria.

Citation Format: Yang H, Wang S, Shen D, Cao Y, Tong F, Chen D, Liu P, Peng Y. Incorporation of MSKCC nomogram to guide the application of intra-operative sentinel lymph node frozen section evaluation in patients with early breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-43.

Nitric oxide inhibits the transcription of E6 gene of human papillomavirus

High-risk human papillomavirus (HPV) is an important pathogenic factor for cervical cancer and understanding the mechanism of HPV gene transcription is important for the prevention and therapy of HPV related cervical cancer. This study aimed to investigate the role of nitric oxide (NO) in the regulation of HPV gene transcription. SiHa cells containing integrated HPV16 were treated with NO donor DETA-NO and cell proliferation and cytotoxicity were determined. HPV gene transcription was detected by real-time PCR. We found no significant cytotoxic effects on SiHa cells when the concentration of DETA-NO was less than 0.5 mmol/l. The transcription of HPV E6 gene was inhibited by DETA-NO in a dose-dependent manner and the best inhibitory effect was observed at 0.5 mmol/l DETA-NO. In addition, ERK inhibitor U0126 decreased the transcription of HPV E6 gene at the concentration of 30 μmol/l. In conclusion, NO inhibits the transcription of HPV E6 gene and probably involves MAPK signaling pathway. Keywords: SiHa cells; nitric oxide; MAPK pathway; HPV transcription.

Distributed compressed sensing based channel estimation for underwater acoustic multiband transmissions

Distributed compressed sensing techniques are applied to enhance sparse channel estimation performance in underwater acoustic multiband systems. The core idea is to use receptions from multiple sub-bands to enhance the detection of channel tap positions. A known variant of the orthogonal matching pursuit (OMP) algorithm based on the distributed compressed sensing principle is simultaneous orthogonal matching pursuit (SOMP). However, the impulse responses across multiple sub-bands may have different arrival structures, although they often show a certain level of similarity. To address such differences at the sub-bands, a multiple selection strategy is applied to select multiple candidates at individual sub-bands at each iteration. This is different from the conventional OMP and SOMP algorithms that select only one candidate at each iteration. When the multiple selection strategy is combined with the SOMP algorithm, the proposed algorithm is referred to as JB-MSSOMP algorithm. To take advantage of channel coherence between adjacent data blocks from different sub-bands, the multiple selection strategy is further used over time. This leads to JBT-MSSOMP algorithm. Computer simulations show improved channel estimation performance of the proposed JB-MSSOMP and JBT-MSSOMP algorithms over the OMP or SOMP algorithms. Communication data from a recent acoustic experiment demonstrates improved receiver performance with the proposed channel estimators.

Exploiting time varying sparsity for underwater acoustic communication via dynamic compressed sensing

While it has been recognized that the multipath structure of the underwater acoustic (UWA) channel offers the potential for compressed sensing (CS) sparsity exploitation, the rapidly time varying arrivals induced by highly dynamic surfaces unfortunately pose significant difficulties to channel estimation. From the viewpoint of underwater acoustic propagation, with the exception of the highly time varying arrivals caused by dynamic surface, generally there exist relatively stationary or slowly changing arrivals caused by direct path or bottom reflection, which imply the adoption of a discriminate estimation method to handle sparse components with different time variation scale. By modeling the time varying UWA channels as a sparse set consisting of constant and time-varying supports, in this paper, estimation of time varying UWA channel is transformed into a problem of dynamic compressed sensing sparse recovery. The combination of a Kalman filter and compressed sensing is adopted to pursue the solution of it. Numerical simulations demonstrate the superiority of the proposed algorithm. In the form of a channel-estimation-based decision-feedback equalizer, the experimental results with the field data obtained in a shallow water acoustic communication experiment indicate that the proposed dynamic compressed sensing algorithm outperforms classic algorithms as well as CS algorithms.

Cystathionine γ-Lyase Is Involved in the Renoprotective Effect of Brief and Repeated Ischemic Postconditioning After Renal Ischemia/Reperfusion Injury in Diabetes Mellitus

BACKGROUND

The aim of this study was to determine whether the protective effects of brief and repeated ischemic postconditioning (IPoC) are associated with the modulation of cystathionine γ-lyase (CSE) expression after renal ischemia/reperfusion (I/R) injury in diabetes mellitus (DM).

METHODS

We subjected diabetic rats to 45 minutes of ischemia followed by reperfusion at 24 hours. Before reperfusion, diabetic rats were treated with 3 cycles of 6 seconds of reperfusion, followed by 6 seconds of ischemia. DL-Propargylglycine (PAG, a CSE inhibitor) was administered to the diabetic rats to investigate its effects on the severity of renal I/R injury in diabetes mellitus (DM). Blood samples and left kidneys were collected for the measurement of blood urea nitrogen (BUN) and serum creatinine (SCr) levels and renal pathologic changes. Western blot and immunochemistry techniques were also performed for the localization of CSE. Levels of superoxidase dismutase (SOD), malonyldialdehyde (MDA), tumor necrosis-alpha (TNF-α), and hydrogen sulfide (H₂S) were quantified using commercially available kits.

RESULTS

The results showed that BUN and SCr levels increased on renal ischemia/reperfusion injury (RI/RI) in the DM group. Diabetic rats treated with IPoC exhibited significantly less renal damage on I/R. Kit measurements showed that IPoC could markedly inhibit the levels of MDA and TNF-α and also improve SOD and H₂S levels. Western blot and immunochemistry showed that expression of CSE was downregulated on I/R in the DM group and IPoC upregulated CSE expression, whereas PAG treatment resulted in opposite effects.

CONCLUSION

Our findings show that brief and repeated IPoC increased the expression of CSE after I/R in DM, and the modulation of CSE may underlie the renoprotective effect of IPoC.

[Advance of Forensic Research in Insulin Poisoning]

Insulin as a common clinical hypoglycemic agent can effectively control serves to lower the concentration of blood glucose. However, insulin overdose can lead to death. In the whole fatal cases of insulin overdose, medical accident is the most common, followed by suicide. Though insulin homicide is extremely rare, it deserves great attention. Though there are some researches about insulin poisoning on forensic toxicology and pathology, it is still a difficult task in forensic practice. In this paper, the mechanism of death, pathological changes, detection methods and diagnose criteria of insulin overdose will be discussed in the view of forensic toxicology and pathology. We hope that this paper could enhance relative knowledges of insulin poisoning for medical examiners.

Cerebral Temperature Dysregulation: MR Thermographic Monitoring in a Nonhuman Primate Study of Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Cerebral thermoregulation remains poorly understood. Temperature dysregulation is deeply implicated in the potentiation of cerebrovascular ischemia. We present a multiphasic, MR thermographic study in a nonhuman primate model of MCA infarction, hypothesizing detectable brain temperature disturbances and brain-systemic temperature decoupling.

MATERIALS AND METHODS

Three Rhesus Macaque nonhuman primates were sourced for 3-phase MR imaging: 1) baseline MR imaging, 2) 7-hour continuous MR imaging following minimally invasive, endovascular MCA stroke induction, and 3) poststroke day 1 MR imaging follow-up. MR thermometry was achieved by multivoxel spectroscopy (semi-localization by adiabatic selective refocusing) by using the proton resonance frequency chemical shift. The relationship of brain and systemic temperatures with time and infarction volumes was characterized by using a mixed-effects model.

RESULTS

Following MCA infarction, progressive cerebral hyperthermia was observed in all 3 subjects, significantly outpacing systemic temperature fluctuations. Highly significant associations were observed for systemic, hemispheric, and global brain temperatures (F-statistic, P = .0005 for all regressions) relative to the time from stroke induction. Significant differences in the relationship between temperature and time following stroke onset were detected when comparing systemic temperatures with ipsilateral (P = .007), contralateral (P = .004), and infarction core (P = .003) temperatures following multiple-comparisons correction. Significant associations were observed between infarction volumes and both systemic (P ≤ .01) and ipsilateral (P = .04) brain temperatures, but not contralateral brain temperature (P = .08).

CONCLUSIONS

Successful physiologic and continuous postischemic cerebral MR thermography was conducted and prescribed in a nonhuman primate infarction model to facilitate translatability. The results confirm hypothesized temperature disturbance and decoupling of physiologic brain-systemic temperature gradients. These findings inform a developing paradigm of brain thermoregulation and the applicability of brain temperature as a neuroimaging biomarker in CNS injury.

[Analysis of newborn screening for galactosemia and genotype-phenotype of confirmed galatosemia cases]

Objective: To investigate the prevalence of galactosemia(GAL), and the characteristics of genotype and phenotype of newborns who were confirmed with GAL in newborn screening in Zhejiang province. Method: The number of all live births, newborn screened infants and all clinical data of confirmed newborns with GAL from October 2013 to March 2015 were retrospectively analyzed by reviewing the data of Zhejiang Province screening center database. And the characteristics of genes and the clinical data of GAL cases who were confirmed by correlative gene test and enzyme activity measurement were analyzed. Result: The prevalence of GAL in Zhejiang province was 1/189 857. Among them, there was 1 case confirmed with GAL typeⅠ (prevalence, 1/759 428), with mutations of c. 904+ 1G>T and c. 687G>A, the enzyme activity of galactose-1-phosphate uridyltransferase (GALT) was 56.4% of controls. And there was 1 case of GAL typeⅡ(prevalence, 1/759 428), with mutations of c. 85G>T and c. 502G>A. There were 2 cases confirmed with GAL type Ⅲ(prevalence, 1/379 714), with mutations of c. 505C>T, c. 452G>A, c. 280G>A and c. 925G>A, the enzyme activity of UDP-galactose-4'-epimerase (GALE) were 42% and 38% of controls, respectively. All cases had different abnormal biochemical marks of liver function, and 1 case had combined hyperlactacidemia or hyperammonemia or increase of multiple kinds of amino acids, respectively. The newborn of GAL type Ⅱ had phacoscotasmus before treatment. All the cases were fed with lactose free milk powder, and all the abnormal parameters were improved during following up. Conclusion: The disease of GAL is rare in Zhejiang province, and its genotype distribution is scattered with comparatively mind clinical manifestations, and the cases with early treatment with lactose free milk powder have good prognosis. All cases needed to be treated and followed up for a life-long time. It is recommended that the high risk cases with GAL should be screened as soon as possible.

[Clinical, biochemical and gene mutation characteristics of short chain acyl-coenzyme A dehydrogenase deficiency by neonatal screening]

Objective: To investigate the incidence, clinical, biochemical and gene mutation characteristics of short chain acyl-coenzyme A dehydrogenase deficiency (SCADD). Method: From January, 2009 to October, 2015, a retrospective analysis of the urine organic acids and acyl-coenzyme A dehydrogenase (ACADS) gene mutation characteristics of patients diagnosed as SCADD by newborn screening using tandem mass spectrometry in Department of Genetics and Metabolism (Newborn screening Center of Zhejiang Province), Children's Hospital, Zhejiang University School of Medicine. Dietary guidance, life management and supplementation of L-carnitine were conducted, and growth and intelligence development were observed during follow-up among the SCADD patients. Result: A total of 1 430 024 neonates, seventeen cases were diagnosed with SCADD with an incidence of 1/84 117. All patients had no clinical symptoms, and intelligence and physical development were normal. Blood butylacyl-carnitine (C4) levels and the ratios increased, C4 0.713.14 μmol/L(reference value 0.03-0.48 μmol/L), C4/C2 0.07-0.23(reference value 0.01-0.04), C4/C3 0.65-2.04(reference value 0.05-0.39). Thirteen with increased urinary ethyl malonic acid (9.30-90.99 mg/g creatinine (reference value 0-6.20 mg/g creatinine )), one patient was accompanied by increased methyl succinic acid (12.33 mg/g creatinine(reference value 0-6.40 mg/g creatinine)), one subject with increased acetylglycine (3.52 mg/g creatinine(reference value 0-0.70 mg/g creatinine)). A total of 13 known mutations were detected in the ACADS gene, 1 homozygous mutation (c.1031A>G), the others are compound heterozygous mutations. One frameshift mutation (c.508_509delGC) and 12 missense mutations were detected. Common mutation were c. 1031A>G(35.3%), c. 164C>T(20.6%) and c. 991G>A(11.8%). SCADD in newborn screening program had no clinical symptoms and normal growth development after 8-42 months follow-up. Conclusion: Cases with SCADD had no clinical symptoms with an incidence of 1/84117. The c. 164C>T and c. 1031A>G may be the common mutations.

Pre-treatment of Stegomyia aegypti mosquitoes with a sublethal dose of imidacloprid impairs behavioural avoidance induced by lemon oil and DEET

The present study was conducted to determine whether imidacloprid can impair the avoidance behaviour of the mosquito Stegomyia aegypti. Laboratory investigations using a T-maze apparatus showed that St. aegypti mosquitoes present long term avoidance behaviour when they are exposed to repetitive trials with lemon oil and DEET. The present study tested the effect of a sublethal dose of imidacloprid on the avoidance behaviour of St. aegypti mosquitoes over a 48 h period. Data suggest that 0.5 ng of imidacloprid/mosquito reduces the avoidance behaviour of mosquitoes exposed to lemon oil, on the first day of exposure, after the second trial; whereas imidacloprid affected DEET repellency only the first day of exposure, after the second trial. Imidacloprid was toxic against St. aegypti mosquitoes, and at sublethal doses was able to impair the repellency induced by lemon oil and DEET. The present data were consistent with the finding that St. aegypti mosquitoes exhibit long term avoidance behaviour, and treatment of mosquitoes with a sublethal dose of imidacloprid under DEET application can affect the repellency of DEET against St. aegypti.

Proton resonance frequency chemical shift thermometry: experimental design and validation toward high-resolution noninvasive temperature monitoring and in vivo experience in a nonhuman primate model of acute ischemic stroke

BACKGROUND AND PURPOSE

Applications for noninvasive biologic temperature monitoring are widespread in biomedicine and of particular interest in the context of brain temperature regulation, where traditionally costly and invasive monitoring schemes limit their applicability in many settings. Brain thermal regulation, therefore, remains controversial, motivating the development of noninvasive approaches such as temperature-sensitive nuclear MR phenomena. The purpose of this work was to compare the utility of competing approaches to MR thermometry by using proton resonance frequency chemical shift. We tested 3 methodologies, hypothesizing the feasibility of a fast and accurate approach to chemical shift thermometry, in a phantom study at 3T.

MATERIALS AND METHODS

A conventional, paired approach (difference [DIFF]-1), an accelerated single-scan approach (DIFF-2), and a new, further accelerated strategy (DIFF-3) were tested. Phantom temperatures were modulated during real-time fiber optic temperature monitoring, with MR thermometry derived simultaneously from temperature-sensitive changes in the water proton chemical shift (∼0.01 ppm/°C). MR thermometry was subsequently performed in a series of in vivo nonhuman primate experiments under physiologic and ischemic conditions, testing its reproducibility and overall performance.

RESULTS

Chemical shift thermometry demonstrated excellent agreement with phantom temperatures for all 3 approaches (DIFF-1: linear regression R(2) = 0.994; P < .001; acquisition time = 4 minutes 40 seconds; DIFF-2: R(2) = 0.996; P < .001; acquisition time = 4 minutes; DIFF-3: R(2) = 0.998; P < .001; acquisition time = 40 seconds).

CONCLUSIONS

These findings confirm the comparability in performance of 3 competing approaches to MR thermometry and present in vivo applications under physiologic and ischemic conditions in a primate stroke model.