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Biomedical subjects

C K Ng

Publications and source records attributed to C K Ng.

At least 37 records · Page 2Linked to original sources
PubMed1999

Quantitation of benzodiazepine receptor binding with PET [11C]iomazenil and SPECT [123I]iomazenil: preliminary results of a direct comparison in healthy human subjects.

Although positron emission tomography (PET) and single photon emission computed tomography (SPECT) are increasingly used for quantitation of neuroreceptor binding, almost no studies to date have involved a direct comparison of the two. One study found a high level of agreement between the two techniques, although there was a systematic 30% increase in measures of benzodiazepine receptor binding in SPECT compared with PET. The purpose of the current study was to directly compare quantitation of benzodiazepine receptor binding in the same human subjects using PET and SPECT with high specific activity [11C]iomazenil and [123I]iomazenil, respectively. All subjects were administered a single bolus of high specific activity iomazenil labeled with 11C or 123I followed by dynamic PET or SPECT imaging of the brain. Arterial blood samples were obtained for measurement of metabolite-corrected radioligand in plasma. Compartmental modeling was used to fit values for kinetic rate constants of transfer of radioligand between plasma and brain compartments. These values were used for calculation of binding potential (BP = Bmax/Kd) and product of BP and the fraction of free non-protein-bound parent compound (V3'). Mean values for V3' in PET and SPECT were as follows: temporal cortex 23+/-5 and 22+/-3 ml/g, frontal cortex23+/-6 and 22+/-3 ml/g, occipital cortex 28+/-3 and 31+/-5 ml/g, and striatum 4+/-4 and 7+/-4 ml/g. These preliminary findings indicate that PET and SPECT provide comparable results in quantitation of neuroreceptor binding in the human brain.

Adult↗
PubMed1998

Presence of cartilage-derived morphogenetic proteins in articular cartilage and enhancement of matrix replacement in vitro.

OBJECTIVE: To investigate the effects of the cartilage-derived morphogenetic proteins (CDMPs) in an in vitro cartilage explant model that mimics the chondrocytic response to matrix depletion, and to demonstrate their presence in articular cartilage. METHODS: Adult bovine articular cartilage and postmortem specimens from adult human donors with and without osteoarthritic (OA) lesions were stained by immunohistochemistry using polyclonal antibodies specific for CDMP-1 and CDMP-2. Extracts of bovine articular cartilage were analyzed by Western blotting for the presence of the CDMPs. Bovine articular cartilage explants were depleted of their matrix by trypsin digestion, followed by a 7-day culture period in a chemically defined serum-free basal medium (BM), with or without recombinant CDMPs 1 and 2. The metabolic activity of chondrocytes was measured by 35S-sulfate incorporation into macromolecules. Newly synthesized proteoglycans (PGs) were analyzed using Sephacryl S-500 HR gel chromatography. The expression levels of the messenger RNA (mRNA) for chondrogenic markers were investigated by Northern analysis. RESULTS: CDMP-1 and CDMP-2 were detected in both bovine and human healthy and OA articular cartilage. Treatment of matrix-depleted cartilage explants with CDMPs 1 and 2 increased equally the incorporation of 35S-sulfate into PGs compared with tissue maintained in BM. Gel chromatography analysis indicated that aggrecan was the predominant PG species. Northern blot analysis showed that the expression of link protein, type II collagen, and aggrecan mRNA transcripts was not modulated by CDMP treatment. CONCLUSION: This study shows the presence of CDMP-1 and CDMP-2 in adult bovine and human articular cartilage. In addition, our in vitro data indicate that CDMPs 1 and 2 stimulate the metabolic activity of articular chondrocytes. Therefore, these signaling molecules may be contributing to the maintenance of the integrity of the joint surface.

Animals↗
PubMed1998

Effect of hyperinsulinemia on myocardial fluorine-18-FDG uptake.

UNLABELLED: This study was performed to evaluate the effect of insulin on myocardial kinetics of 18F-fluorodeoxyglucose (FDG) and glucose in patients with ischemic heart disease. METHODS: Twelve male patients (age range 54-79 yr; mean age 69 +/- 8 yr) were studied during the fasting awake state. Patients with diabetes and previous myocardial infarction of the left anterior descending vascular bed were excluded from the study. Patients were injected with a 185-MBq (5-mCi) bolus of FDG during arterial and coronary sinus catheterization. Thirty minutes after FDG injection, paired basal arterial and coronary sinus blood samples were taken for the measurement of FDG and glucose uptake. Thereafter, a primed (100 mU x m(-2) x min(-1) for 10 min) continuous (50 mU x m(-2) x min(-1) infusion of insulin was administered for 60 min using the euglycemic clamp technique, and blood samples were repeated. Blood samples also were taken periodically for the measurement of arterial free fatty acids and insulin. RESULTS: Euglycemic insulin infusion lowered arterial concentrations of free fatty acids, reducing myocardial extraction of free fatty acids by 85% and stimulated uptake of glucose and FDG. Myocardial glucose and FDG extraction fractions (%) increased from 1 +/- 1 and 2 +/- 2 at baseline to 8 +/- 2 and 10 +/- 3 during insulin infusion, respectively. The lumped constant value was estimated to be 1.44 +/- 0.14 (r = 0.87) for the fasted state, 0.99 +/- 0.07 (r = 0.74) during insulin infusion and 1.00 +/- 0.05 (r = 0.92) when both groups of data were pooled together. CONCLUSION: The data obtained in this study show that FDG uptake quantitatively traces glucose uptake during physiological hyperinsulinemia in patients with ischemic heart disease.

Aged↗
PubMed1997

Effect of left ventricular function on the assessment of myocardial viability by technectium-99m sestamibi and correlation with positron emission tomography in patients with healed myocardial infarcts or stable angina pectoris, or both.

The accuracy of technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) for the assessment of myocardial viability in patients with coronary artery disease and left ventricular (LV) dysfunction is not defined completely. This study determines whether the performance of Tc-99m sestamibi SPECT for viability detection differs between patients with mild-to-moderate coronary artery disease. Patients with regional and/or global LV dysfunction were separated into 2 groups on the basis of LV ejection fraction (EF) at rest: group 1 (LVEF > 25%, mean 36 +/- 6%, n = 9), and group 2 (LVEF < or = 25%, mean 17 +/- 5%, n = 11). All patients underwent semiquantitative Tc-99m sestamibi SPECT and positron emission tomography (PET) at rest with N-13 ammonia and F-18 fluorodeoxyglucose. The overall regional concordance of SPECT and PET for viability detection was 89% in group 1 and 78% in group 2 (p = 0.002). Discordance in group 2 was almost exclusively due to PET viable and/or SPECT nonviable regions. In regions with hypoperfusion at rest by PET, concordance was 78% in group 1 and only 64% in group 2 (p = 0.0015). In regions with reduced perfusion and relatively increased metabolic activity ("flow: metabolism mismatch"), Tc-99m sestamibi SPECT identified 88% of regions in group 1 as viable, but only 42% of regions in group 2 (p = 0.002). Thus, while Tc-99m sestamibi semiquantitative SPECT at rest shows a good concordance with PET for the detection of myocardial viability in patients with coronary artery disease with mild-to-moderate LV dysfunction, it may underestimate myocardial viability in patients with severe LV dysfunction, particularly in those patients with hypoperfusion at rest as assessed by PET.

Adult↗
PubMed1997

Positron emission tomography measurement of cerebral metabolic correlates of yohimbine administration in combat-related posttraumatic stress disorder.

BACKGROUND: We have previously reported an increase in symptoms of anxiety in patients with posttraumatic stress disorder (PTSD) following administration of the beta 2-antagonist yohimbine, which stimulates brain norepinephrine release. Preclinical studies show decreased metabolism in the neocortex and the caudate nucleus with high-dose yohimbine-induced norepinephrine release, but low levels of norepinephrine release result in an increase in metabolism in these areas. METHODS: We used positron emission tomography and fludeoxyglucose F 18 to measure brain metabolism in Vietnam combat veterans with PTSD (n = 10) and healthy age-matched control subjects (n = 10), following administration of yohimbine (0.4 mg/kg) or placebo in a randomized, double-blind fashion. RESULTS: Yohimbine resulted in a significant increase in anxiety in the patients with PTSD, but not in healthy subjects. There was a significant difference in brain metabolic response to yohimbine in patients with PTSD compared with healthy subjects in prefrontal, temporal, parietal, and orbitofrontal cortexes. Metabolism tended to decrease in patients with PTSD and increase in healthy subjects following administration of yohimbine. CONCLUSION: These findings are consistent with our previous hypothesis of enhanced norepinephrine release in the brain with yohimbine in patients with PTSD.

Anxiety Disorders↗
PubMed1997

Positron emission tomography measurement of cerebral metabolic correlates of tryptophan depletion-induced depressive relapse.

BACKGROUND: Short-term depletion of plasma tryptophan has been shown to result in depressive relapse in patients with remission of major depression. Positron emission tomography and single photon emission computed tomography studies implicated the dorsolateral prefrontal cortex, orbitofrontal cortex, thalamus, and caudate nucleus in the pathogenesis of depression. The purpose of this study was to measure cerebral metabolic correlates of tryptophan depletion-induced depressive relapse. METHODS: Patients diagnosed as having major depression (N = 21) who clinically improved with serotonin reuptake inhibitors underwent 2 test days involving tryptophan depletion or placebo, followed 6 hours later by positron emission tomography scanning with fludeoxy-glucose F18. Brain metabolism was compared in patients with (n = 7) and without (n = 14) a tryptophan depletion-induced depressive relapse. RESULTS: Tryptophan depletion resulted in a decrease in brain metabolism in the middle frontal gyrus (dorsolateral prefrontal cortex), thalamus, and orbitofrontal cortex in patients with a depletion-induced depressive relapse (but not in patients without depletion-induced relapse). Decreased brain metabolism in these regions correlated with increased depressive symptoms. Baseline metabolism was increased in prefrontal and limbic regions in relapse-prone patients. CONCLUSION: Specific brain regions, including the middle frontal gyrus, thalamus, and orbitofrontal cortex, may mediate the symptoms of patients with major depression.

Antidepressive Agents↗
PubMed1997

Identification of a promoter for the latent membrane protein 1 gene of Epstein-Barr virus that is specifically activated in human epithelial cells.

Latent membrane protein 1 (LMP 1) is one of two Epstein-Barr virus (EBV)-encoded proteins that expressed in nasopharyngeal carcinoma (NPC) cells. Previous studies showed that a 3.5-kb transcript of the LMP 1 gene, in addition to the 2.8-kb transcript, was detected in a B95-8-EBV-containing, nude mice-passaged NPC tumor, C15. This indicated that a transcript was initiated from a region 5' to the putative promoter, ED-L1. We have isolated an EBV variant from a NPC tissue, and this virus strain contained a more pathogenic LMP 1 gene. DNA sequence analysis of the 5'-upstream region showed distinct variations as compared to that of B95-8 strain. To test if the LMP 1 gene of the NPC strain also contained an upstream promoter, we generated a series of deletion plasmids encompassing positions -1,030 to +20 of the LMP 1 promoter and tested for their abilities to drive the expression of the reporter gene in human epithelial cell lines, C-33A and NPC-TW076. We found that the region between -643 and -496 contained a promoter activity that was approximately five-fold higher than the putative promoter, ED-L1. This region between -643 and -496 was designated as ED-L1E. C-33A cells containing the genomic clone pT7(E) or the clone that had deleted a 94-bp ED-L1 sequence (delta94) was used to determine the transcription initiation sites by RNase protection assay. Results showed that a transcription initiation site was located at nucleotide 170,099 ("A") of EBV genome. The transcript was expressed in NPC biopsies and in human primary normal epithelial cells transfected with pT7(E) and delta94, respectively, as examined by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Furthermore, the ED-L1E was not regulated by the EBV-encoded nuclear antigen 1-mediated transcriptional enhancer family of repeats (FR) in C-33A cells. Our results suggested that the ED-L1E was specifically activated in epithelial cells. The biological significance of the selective usage of the ED-L1E promoter was discussed.

B-Lymphocytes↗
PubMed1996

Inspiratory gas flow induced by cardiac systole.

This study was made to quantify the inspiratory gas flow pulse produced by cardiac systole. Ten adults (9 men, 1 woman; age 24-65 yr) were studied, of whom two had respiratory muscle weakness. The inspiratory flow pulse commenced 50-60 msec after the R wave of the ECG and lasted 106 (SD22) msec. In eight subjects seated and breathing through a mouthpiece, the flow pulse reached a peak of 120 (SD 58) ml sec-1 and displaced a volume of 6.6 (SD 2.3) ml (range 3.6-9.9 ml). Similar results were obtained using a nasal mask. By adding an external airway resistance, the effective intrathoracic pressure responsible for inspiratory flow was estimated to be -0.21 (SD 0.03) cm H2O. Duplicate studies showed little variation in pulse volume. The mechanism of the inspiratory gas flow pulse and its contribution to gas exchange is discussed.

Adult↗
PubMed1996

Clinical presentation of rupture of the left-ventricular free wall after myocardial infarction: report of five cases with successful surgical repair.

Rupture of the left-ventricular free wall may not always result in immediate irreversible hemodynamic collapse. We report a series of five patients (4 male, 1 female; age 59-79 years) successfully operated for postinfarction free-wall rupture with good long-term results. Two patients presented with syncopy and acute tamponade three days after an acute myocardial infarction. In two patients with atypical chest pain and congestive heart failure, a large pericardial effusion and an extreme localized thinning of a myocardial scar region was seen several weeks after an uncomplicated myocardial infarct. In one patient a pseudoaneurysm was detected, which developed asymptomatically within three weeks after a posterior myocardial infarct. In all cases myocardial rupture was suspected after an echocardiographic examination. At surgery a hemopericardium and a localized rupture site were found. The surgical procedure included closure of the defect by direct suture or patch, CABG in 3 cases, and mitral valve replacement in one patient. The postoperative course was uneventful, only one patient needed IABP for 24 hours. Three patients returned to NYHA functional class I, one patient to class II, and one patient to class III. The latter patient died of heart failure 17 months postoperatively, and the other patients are still alive 4,18,24, and 26 months postoperatively. Thus clinical representation of left-ventricular free-wall rupture after myocardial infarction can be highly variable. But close cooperation between experienced echocardiographers and surgeons may allow successful corrections with good long term-results.

Aged↗
PubMed1996

[Ostium stenosis of the left coronary artery after aortic valve replacement--2 case reports].

The development of left main coronary artery stenosis is a rare complication arising after aortic valve replacement. We report the different clinical course of two cases. One patient developed typical exertional angina 3 months after uneventful aortica valve replacement. Coronary stenosis had been excluded on preoperative coronary angiography. One day before hospital admission for coronary angiography the patient died suddenly. The second patient reported symptoms typical of angina 6 months after aortic valve replacement. Coronary angiography revealed critical left coronary ostial stenosis, which was successfully treated by surgical revascularization. These cases demonstrate the rare, yet potentially fatal complication of left coronary ostial stenosis. Early coronary angiography seems warranted in the event of typical exertional angina, even after angiographic exclusion of relevant coronary artery stenosis before aortic valve replacement.

Aortic Valve Stenosis↗
PubMed1996

Two case reports of delayed skin burns from methylisothiazolines used in water treatment.

Kathon CG and Kathon WT are biocides containing 5-Chloro-2-Methyl-4-Isothiazoline-3-One (MCI) and 2-Methyl-4-Isothiazoline-3-One (MI) in a 3:1 ratio. These compounds are used as preservatives in skin care products and there have been many reports of allergic contact dermatitis due to Kathon used in this context. They are also widely used in industry as preservatives in metal working fluids, latex emulsions and for water treatment. Two cases of severe irritant contact dermatitis through accidental exposure to high concentrations of Kathon in industrial settings are reported to highlight the importance of worker education and the use of personal protective equipment when handling this corrosive chemical.

Burns, Chemical↗
PubMed1995

Detection of an Epstein-Barr-virus variant in T-cell-lymphoma tissues identical to the distinct strain observed in nasopharyngeal carcinoma in the Taiwanese population.

An EBV variant has been identified in NPC tissues in Taiwan. This EBV variant contains a point mutation in exon I of the LMP I gene. This mutation results in the loss of an XhoI site at nt 169,426, which is present in strain B95-8. In addition, this variant contains a 30-bp deletion in exon 3 of the gene. The recent demonstration of the prevalence of EBV-containing nasal and peripheral T-cell lymphoma in this region drove us to evaluate the presence of this NPC-EBV strain in 7 cases of T-cell lymphoma, as well as in 48 NPC tissues, 2 cases of Hodgkin's disease and I B-cell lymphoma. Four samples of normal lymph node tissue, 40 of normal nasopharynx tissue and 78 throat washings of healthy individuals were included for comparison. We used sequence-specific primers and the polymerase chain reaction (PCR) method to amplify LMP I gene fragments containing these variations. Mutations were then confirmed by restriction-enzyme digestion and the DNA sequencing analysis. Our results showed that 57 of 58 tumor-tissues samples were EBV-positive. Among them, 56, including 6 T-cell-lymphoma samples, belonged to the NPC strain. This strain of EBV was also present in 92% of EBV-positive normal nasopharynx tissues and in 84% of EBV-positive throat washings of the healthy individuals tested. These results suggest that the NPC-EBV strain is prominently present in Taiwan.

Base Sequence↗
PubMed1995

Kinetic analysis of technetium-99m-labeled nitroimidazole (BMS-181321) as a tracer of myocardial hypoxia.

BACKGROUND: Experimental data have indicated that [99mTc]-nitroimidazole (BMS-181321) is preferentially taken up in hypoxic tissue; its kinetics, however, has not been fully investigated. The purpose of this study was to address the relation between perfusate oxygen level and myocardial retention of [99mTc]nitroimidazole. METHODS AND RESULTS: Bolus injection and constant infusion experiments were performed in Langendorff buffer-perfused rat hearts in normoxic and hypoxic conditions. Data were acquired with a pair of NaI detectors. The initial clearance rate of [99mTc]nitroimidazole was approximately 20 seconds and independent of perfusate oxygen level. The slow clearance rate was greater than 3 hours in all perfusion conditions. The tissue retention of [99mTc]nitroimidazole varied from 0.61 +/- 0.14% in normoxic conditions to 5.94 +/- 1.16% in the most severe hypoxic conditions. In addition, tissue retention was inversely proportional to perfusate oxygen level in a sigmoidal manner. The constant infusion experiments established that the binding rate at 25% oxygen level (1.94 +/- 0.38 mL of perfusate/min-g dry wt) was twofold of that at 40% and sevenfold at 100%. The binding rate of [99mTc]nitroimidazole was independent of the perfusion sequence, suggesting irreversible binding. CONCLUSIONS: These data indicate that [99mTc]nitroimidazole may be a useful tracer for the identification of myocardial hypoxia. A sigmoidal relation was demonstrated for the uptake of the tracer, which suggests that a threshold level of hypoxia is necessary for the uptake of the tracer.

Animals↗
PubMed1995

Comparison of sestamibi single-photon emission computed tomography with positron emission tomography for estimating left ventricular myocardial viability.

Technetium-99m methoxyisobutyl isonitrile (technetium-99m sestamibi [MIBI]) is distributed in the myocardium according to blood flow. Reports comparing stress rest sestamibi protocols with reinjection thallium or resting fluorodeoxyglucose (FDG), or both, in patients with coronary artery disease have shown appreciable discordance regarding myocardial viability in these settings. We performed this analysis with regard to regional comparisons within discordant segments and made comparisons in a subset of patients who underwent revascularization. Thirty-seven patients with coronary artery disease had single-photon emission computed tomography MIBI, N-13 ammonia/18FDG positron emission tomography (PET), and radionuclide ventriculography performed at rest. One hundred two segments were viable and 29 were nonviable by both MIBI and FDG. The concordance was 71%. In MIBI nonviable/FDG viable segments, most of the discordance was in the inferior wall. In MIBI nonviable discordant segments, FDG accurately predicted an increase in percent regional ejection fraction (preoperative 36% [+/- 5 SE] to postoperative 48% [+/- 5.5 SE][p < 0.0006]). MIBI underestimates myocardial viability as assessed by PET. Seventy-one percent of myocardial segments were concordant by both quantitative sestamibi single-photon emission computed tomography and FDG PET. Discordance in MIBI nonviable segments was predominantly in the inferior wall. PET can be helpful in detecting myocardial viability in patients suspected of having had MIBI nonviability in the inferior wall.

Adult↗
PubMed1995

Effect of exogenous hyaluronan and hyaluronan oligosaccharides on hyaluronan and aggrecan synthesis and catabolism in adult articular cartilage explants.

The addition of hyaluronan to the culture medium of explant cultures of articular cartilage was shown to suppress the synthesis of hyaluronan and aggrecan, the major proteoglycan present in cartilage, and resulted in a greater proportion of the newly synthesized aggrecan and hyaluronan appearing in the culture medium. This effect of exogenous hyaluronan on aggrecan and hyaluronan synthesis was concentration-dependent and reversible on removal of the glycosaminoglycan from the culture medium. The addition of tetra- and hexasaccharides derived from Streptomyces sp. hyaluronidase digestion of hyaluronan to explant cultures of articular cartilage did not change the rate of synthesis of aggrecan or hyaluronan or their ultimate distribution between tissue and medium. However, the addition of tetra- and hexasaccharides of hyaluronan resulted in a decrease in the rate of loss of hyaluronan from the tissue but not that of aggrecan, which remained the same as in control cultures. This suppression of the rate of loss of hyaluronan was eliminated on removal of the hyaluronan oligosaccharides from the culture medium. Analysis of the hydrodynamic size of the newly synthesized hyaluronan indicated that the presence of hyaluronan tetra- and hexasaccharides brought about an accumulation of hyaluronan of intermediate molecular mass. Since no radiolabeled hyaluronan was detected in the culture medium, it was concluded that the tetra- and hexasaccharides inhibited the internalization and intracellular catabolism of hyaluronan by the cartilage explant cultures. Regardless of whether hyaluronan or tetra- and hexasaccharides of hyaluronan were added to the culture medium, newly synthesized hyaluronan underwent depolymerization at a rate consistent with a mechanism involving oxygen-derived radicals.

Adult↗
PubMed1995

Synthesis and PET imaging of the benzodiazepine receptor tracer [N-methyl-11C]iomazenil.

The central benzodiazepine receptor tracer [N-methyl-11C]iomazenil (Ro 16-0154) was synthesized by alkylation of the desmethyl precursor noriomazenil with [11C]methyl iodide. The [11C]CH3I (prepared by reduction of [11C]CO2 with LiA1H4 followed by reaction with HI) was reacted with noriomazenil in N,N-dimethylformamide and Bu4N+OH- for 1 min at 80 degrees C and purified by HPLC (C18, 34% CH3CN/H2O 7 mL/min). The product was obtained with synthesis time 35 +/- 5 min (mean +/- SD, n = 7), radiochemical yield (EOB) 36 +/- 16%, radiochemical purity 99 +/- 1%, and specific activity 5100 +/- 2800 mCi/mumol. Absorbed radiation doses were calculated from previously acquired human biodistribution data. The urinary bladder wall received the highest dose (0.099 mGy/MBq) for 4.8 h voiding interval and the effective dose equivalent was 0.015 mSv/MBq. After i.v. injection of [11C]iomazenil in an adult baboon or healthy human volunteer, radioactivity accumulated in the cortex with time-activity curves in agreement with results obtained with [11C]flumazenil PET and [123I]iomazenil SPECT studies. The count rate was sufficient to obtain quantitative images up to 2 h post-injection with a 14 mCi injection. These results suggest that [11C]iomazenil will be a useful agent for measuring benzodiazepine receptors in vivo by positron emission tomography.

Adult↗
PubMed1994

Validation of a model for [1-11C]acetate as a tracer of cardiac oxidative metabolism.

To develop a compartmental model for estimating myocardial oxygen consumption rate (MVO2) with [1-11C]acetate, the metabolic fate of radiolabeled acetate was determined in normoxic and ischemic conditions in isolated perfused rat hearts. Glutamate composed 63 +/- 1 and 44 +/- 7% of the total tissue radioactivity 2 min postinjection in normoxic and ischemic myocardium, respectively, and radiolabeled glutamate remained the largest fraction throughout 40 min of perfusion. Based on the biochemical pathway of the tracer and the temporal distribution of 14C-labeled metabolites, a six-compartment model was formulated. Studies using [1-11C]acetate and a pair of NaI detectors were then performed in the same perfused heart system to validate the model. Consistency between the model predictions and biochemical measurements of tissue and effluent metabolites supported the validity of the kinetic model in normoxic and ischemic conditions. Model-estimated MVO2 correlated well with experimentally measured MVO2 for normoxic, hypoxic, and ischemic conditions, with a slope of 0.97 (r = 0.95). In addition, the model-estimated rate constant, k42, which corresponded to the oxidative flux, correlated strongly with the myocardial clearance rate (k1 or kmono) determined from the tissue kinetics. These findings provide a mechanistic basis for the use of k1 or kmono as an index of MVO2 in both normoxic and ischemic myocardium studied with [1-11C]acetate and positron emission tomography.

Acetates↗