Membrane Cell Proliferation Research Articles

99mTc]Tc-DTPA-Bis(cholineethylamine) as an Oncologic Tracer for the Detection of Choline Transporter (ChT) and Choline Kinase (ChK) Expression in Cancer.

Objective: The elevated choline transporters (ChT), choline kinase (ChK), choline uptake, and phosphorylation in certain tumor cells have influenced the development of radiolabeled choline derivatives as diagnostic probes for imaging cell membrane proliferation. We, therefore, aimed to develop a choline-based moiety for imaging choline kinase-overexpressed tumors by single-photon emission tomography (SPECT). A novel choline-based diagnostic probe was synthesized and evaluated preclinically in various ChT- and ChK-overexpressed tumor models for SPECT imaging applications. Methods: The synthesis of diethylenetriaminepentaacetic acid-bis-choline ethylamine [DTPA-bis(ChoEA)] featured the conjugation of dimethylaminoethanol to a bifunctional chelator DTPA anhydride. [99mTc]Tc-DTPA-bis(ChoEA) was prepared, and its in vivo characteristics were evaluated in BALB/c mice and tumor-xenografted PC3, A549, and HCT116 athymic mouse models. The in vitro parameters, including cell binding and cytotoxicity, were assessed in PC3, A549, and HCT116 cell lines. To evaluate the specificity of the radioprobe, competitive binding studies were performed. Small-animal SPECT/CT diagnostic imaging was performed for in vivo evaluation. The mouse biodistribution data was further investigated to estimate the radiation dose in humans. Results: In silico studies suggested high binding with enhanced specificity. A standard radiolabeling procedure using stannous chloride as a reducing agent showed a labeling yield of 99.5 ± 0.5%. The in silico studies suggested high binding with enhanced specificity. [99mTc]Tc-DTPA-bis(ChoEA) showed high in vitro stability and specificity. The pharmacokinetic studies of [99mTc]Tc-DTPA-bis(ChoEA) in mice showed an increased tumor-to-background ratio after few minutes of intravenous administration. The first-in-human trial was also conducted. The effective dose was estimated to be 0.00467 mSv/MBq (4.67 mSv/GBq), resulting in a radiation dose of up to 1.73 mSv for the 370 MBq injection of [99mTc]Tc-DTPA-bis(ChoEA). Conclusions: The synthesized radioprobe [99mTc]Tc-DTPA-bis(ChoEA) accumulates specifically in choline kinase-overexpressed tumors with a high signal-to-noise ratio. The preclinical and first-in-man data suggested that [99mTc]Tc-DTPA-bis(ChoEA) could potentially be used as a diagnostic SPECT tracer in the monitoring and staging of cancer.

Localization of feeding of Anomalococcus indicus (Hemiptera: Lecanodiaspididae) and supplementary biological notes: towards the biological management of the invasive tree Vachellia nilotica indica (Fabales: Mimosoideae) in North-Eastern Australia

Summary. Management of the invasive Vachellia nilotica indica infesting tropical grasslands of Northern Australia has remained unsuccessful to date. Presently Anomalococcus indicus is considered a potential agent in the biological management of V. n. indica. Whereas generic biological details of A. indicus have been known, their feeding activity and details of their mouthparts and the sensory structures that are associated with their feeding action are not known. This paper provides details of those gaps. Nymphal instars I and II feed on cortical-parenchyma cells of young stems of V. n. indica, whereas nymphal instars III and adult females feed on phloem elements of older shoots. Nymphal instars and adults (females) trigger stress symptoms in the feeding tissue with cells bearing enlarged and disfigured nuclei, cytoplasmic shrinkage, cytoplasmic trabeculae, abnormal protuberances and uneven cell wall thickening, unusual cell membrane proliferation, and exhausted and necrosed cells. Continuous nutrient extraction by A. indicus can cause stem death. We provide evidence that A. indicus, by virtue of its continuous feeding activity and intense population build up, can be an effective biological-management agent to regulate populations of V. n. indica in infested areas.

Metabolic Mapping of Gliomas Using Hybrid MR-PET Imaging

The most powerful adjunct to histopathology for the grading of gliomas seems to be the metabolic imaging using positron emission tomography and magnetic resonance spectroscopy (MRS). The purposes of this study were to examine the feasibility of simultaneous acquisition of both techniques for purposes of tumor grading in a newly launched hybrid magnetic resonance positron emission tomography (MR-PET) and to examine the spatial distributions of metabolic changes in gliomas. Twenty-eight consecutive patients with gliomas underwent simultaneous methionine (Met) MR-PET imaging for detection of the most malignant tumor part before surgical sampling. After coregistration and fusion of MR-PET and MRS data, tumor to normal brain (T/N) Met uptake ratios and the corresponding metabolites peaks (choline [Cho], creatine [Cr], and N-acetylaspartate [NAA]) in MRS were recorded. The patients were divided into 4 types on the basis of the relation between the Met uptake area and the increased metabolite ratios: type I, the increased Met uptake area had at least 50% overlap or was completely within the area of increased Cho/NAA ratio; type II, the increased Met uptake site had less than 50% overlap of increased Cho/NAA ratio site; type III, the increased Met uptake region had no spatial relationship with the "hot" lesions in the MRS maps; and type IV, there was no pathologically increased Met uptake. The surgical sampling was performed in the tumor part with the highest Met uptake and, in the absence of increased Met accumulation, in the site with the highest Cho/NAA ratio. All surgical samples were referred to the neuropathology division for histological grading. A total of 16 low-grade gliomas (World Health Organization grade II) and 12 high-grade gliomas (World Health Organization grade III) were included. Three lesions (10%) of type I were identified. Four lesions (14%) were classified as type II and 6 lesions (21%) were classified as type 3, where the increased Met uptake region had no spatial relationship with the hot lesions in the MRS maps. In 15 of the 28 patients (54%), there was no increased Met accumulation (type 4 lesions). Maps of Cho/NAA and Cr/NAA showed a close spatial relationship in most of the patients. Median T/N Met uptake ratio in the pooled surgically sampled tumor sites was 1.6 (range, 1-3), and median Cho/NAA and Cho/Cr ratios were 2.1 (range, 0.9-5.8) and 1.5 (range, 0.5-8.3), respectively. Spearman rank correlations of the metabolic markers in the low-grade gliomas showed significant correlations between Met uptake and Cr/NAA ratio (ρ = 0.59; P = 0.015) as well as between Cho/NAA and Cr/NAA ratios (ρ = 0.79; P = 0.0002). The normalized tumor creatine was significantly higher in anaplastic tumors compared with the low-grade gliomas (P = 0.001). A tendency for a significant positive correlation was found between normalized tumor creatine and Met uptake in the anaplastic tumors. Metabolic mapping before histological sampling is feasible using simultaneous MR-PET imaging. High T/N Met uptake ratio reflecting high expression of amino-acid membrane transporters, which is indicative of proliferating tumor cell populations, does not always spatially correlate with neuronal cell loss and cell membrane proliferation (Cho/NAA) seen in MRS. Increased Cr/NAA is associated with increased methionine uptake in low-grade gliomas, whereas normalized creatine in tumor tends to correlate with methionine accumulation, which indicates a possible coupling of these metabolic indices in anaplastic tumors. Thus, spatial distribution differences in gliomas should be taken into account when planning surgical sampling.

Differences in Metabolism of Fiber Tract Alterations in Gliomas

Gliomas propagate diffusely throughout and along white matter structures. Glioma-related changes in structural integrity and metabolism are not detectable by standard magnetic resonance (MR) imaging. To investigate differences in the metabolism of fiber tract alterations between gliomas grade II to IV by correlation of fiber density values with metabolite concentrations measured by fiber density mapping and MR spectroscopic imaging. Fiber density mapping and MR spectroscopic imaging were performed in 48 patients with gliomas WHO grade II to IV. Fiber density mapping data were used to define fiber tracts in tumoral and peritumoral areas. Structural integrity of fiber tracts was assessed as fiber density ipsilateral-to-contralateral ratio (FD ICR). Metabolite concentrations for choline-containing compounds and N-acetyl-aspartate were computed and correlated to FD ICR values after coregistration with anatomic MR imaging. In tumoral areas, choline-containing compound concentrations of altered fiber tracts were significantly different between low- and high-grade glioma and showed different courses for the correlations of FD ICR and choline-containing czeompounds. In high-grade glioma, increasing fiber destruction was associated with a massive progression in cell membrane proliferation. Peritumoral fiber structures showed significantly decreased N-acetyl-aspartate concentrations for all patients, but only patients with glioblastoma multiforme had significantly decreased fiber density compared with the contralateral side. Glioma grades II and III had significantly higher peritumoral FD ICR than glioblastoma multiforme. A multiparametric MR imaging strategy providing information about both structural integrity and metabolism of the tumor is required for detailed assessment of glioma-related fiber tract alterations, which in turn is essential for treatment planning.

Her-2 and targeted treatment for gastric cancer

Her-2( human epidermal growth fact or receptor 2) is a type of 185 kD across the membrane glycoprotein with tyrosine kinase activity,play an important function in the cell divisions across a cell membrane proliferation signal transduction,and finally affect biological activities of tumor cells from multiple ways,such as a tumor cell proliferation and adhesion,transfer and differentiation and other related gene regulation.Recent studies show that Her-2 overexpression rate of gastric cancer patients is about 12％ ～ 35％,and Her-2 is a gastric cancer poor-prognostic factors,while Her-2 monoclonal antibody-Trastuzumab is expected to become a new standard gastric cancer treatment for the patients with Her-2 overexpressed. Key words: Stomach neoplasms ; Targeted therapy ; Trastuzumab ;

Design, synthesis and biological evaluation of choline based SPECT imaging agent: Ga(iii)-DO3A-EA-Choline

The enhanced choline uptake and phosphorylation in tumor cells has motivated the development of radiolabeled choline derivatives as diagnostic markers for imaging cell membrane proliferation and noninvasive detection of prostate, brain and breast tumors. In the present work, we report a facile strategy for the synthesis of choline functionalized macrocyclic chelating agent (DO3A-EA-choline) and its radiocomplexation with (67)Ga for potential tumor imaging applications. The synthesis of the desired compound featured quaternization of N,N-dimethylaminoethanol with 1,2-dibromoethane followed by subsequent alkylation with trisubstituted cyclen (DO3A). All intermediates and final compounds have been fully characterized by spectroscopic techniques, namely, (1)H, (13)C NMR and mass spectroscopy. The compound has been successively labeled with (67)Ga-citrate in ammonium acetate buffer (pH 6.5) at 80 °C. MTT assays have been performed on the HEK cell line to determine the cytotoxicity of the compound. Cell uptake studies carried out on the U-87 MG cell line exhibited saturable binding of the radioconjugate in picomolar range with a K(d) value of 0.528 pM. The in vivo biodistribution and blood kinetics studies exhibited rapid clearance of the radiolabeled complex and excretion through the renal and hepatobiliary route. The present studies demonstrate the potential applications of (67)Ga-DO3A-EA-choline as a radiopharmaceutical for molecular imaging using ((67/68)Ga) SPECT and PET modalities.

Proton Magnetic Resonance Spectroscopic Imaging in the Border Zone of Gliomas

We sought to retrospectively investigate differences in correlation of absolute metabolites concentrations and metabolite ratios with histopathologic parameters of stereotactic biopsies from the border zone of gliomas. Proton magnetic resonance spectroscopic imaging (H-MRSI) with high spatial resolution was performed in 10 glioma patients at 1.5 T. Magnetic resonance spectroscopic imaging (MRSI) data were coregistered to a 3D MR data set used for stereotactic procedures. Metabolite concentrations of choline-containing compounds (Cho), creatine (Cr), and total N-acetyl-aspartate (tNAA) in addition to metabolite ratios of Cho/Cr, tNAA/Cr, and Cho/tNAA were calculated for voxel positions at biopsy loci with low tumor cell infiltration. Metabolite values were correlated with histopathologic findings expressed as a relative (% tumor infiltration, %TI) and an absolute parameter (tumor cell number, TCN). We found a strong negative linear correlation for tNAA with %TI (R = -0.773, P < 0.001) and TCN (R = -0.769, P < 0.001) but no correlation for Cho (P > 0.05). On the other hand, the metabolite ratio of Cho/Cr showed a moderate positive linear correlation with %TI (R = 0.523, P = 0.012) and TCN (R = 0.486, P = 0.019), but no correlation was obtained for tNAA/Cr (P > 0.05). Differences in correlation between tNAA and Cho as well as tNAA/Cr and Cho/Cr were significant for both %TI (P = 0.012 and P = 0.024) and TCN (P = 0.016 and P = 0.040) using a t test. We conclude that absolute values of tNAA are more significant than Cho in the detection of low tumor cell infiltration. On the basis of absolute metabolite values, neuronal damage seems to be more distinct than cell membrane proliferation in the border zone of gliomas. Furthermore, the calculation of metabolite ratios versus Cr for the border zone may yield to misleading results because Cr is not constant in this area.

Proton magnetic resonance spectroscopy in childhood brainstem lesions

Diagnosis of brainstem lesions in children based on magnetic resonance imaging alone is a challenging problem. Magnetic resonance spectroscopy (MRS) is a noninvasive technique for spatial characterization of biochemical markers in tissues and gives information regarding cell membrane proliferation, neuronal damage, and energy metabolism. We measured the concentrations of biochemical markers in five children with brainstem lesions and evaluated their potential diagnostic significance. Images and spectra were acquired on a 1.5-T imager. The concentrations of N-acetylaspartate, tetramethylamines (e.g., choline), creatine, phosphocreatine, lactate, and lipids were measured within lesions located at the brainstem using Point-resolved spectroscopy sequences. Diagnosis based on localized proton spectroscopy included brainstem glioma, brainstem encephalitis, demyelination, dysmyelination secondary to neurofibromatosis type 1 (NF 1), and possible infection or radiation necrosis. In all but one patient, diagnosis was confirmed by biopsy or by clinical follow-up. This small sample of patients suggests that MRS is important in the differential diagnosis between proliferative and nonproliferative lesions in patients without neurofibromatosis. Unfortunately, in cases of NF 1, MRS can have a rather misdiagnosis role.

In vivo research in astrocytoma cell proliferation with 1H-magnetic resonance spectroscopy: correlation with histopathology and immunohistochemistry

Assessment of brain tumor proliferative potential provides important prognostic information that supplements standard histopathologic grading. Proton magnetic resonance spectroscopy ((1)H-MRS) gives completely different information, relating to cell membrane proliferation, neuronal damage, energy metabolism and necrotic transformation of brain or tumor tissues. The aim of this study was to investigate the relationship between (1)H-MRS and tumor proliferative potential in astrocytomas. We studied 34 patients with histologically verified astrocytomas using the (1)H-MRS protocol following routine MRI preoperatively. The tumor in 26 of these patients was classified as grade I/II (low grade), and the tumor in the remaining patients as grade III/IV (high grade) according to the World Health Organization classification criteria of nervous system tumors (2000). The tumor in 21 patients was homogeneous astrocytoma, and of these 17 were classified as low grade and 4 as high grade. Expression of proliferating cell nuclear antigen (PCNA) was determined immunohistochemically using streptavidin-biotin-peroxidase complex (SP) staining. The ratios of choline (Cho) to N-acetylaspartate (NAA) and Cho to creatine (Cr) in those with high-grade astrocytomas (n=4) were significantly higher than in those with low-grade astrocytomas (n=17) (t=2.899, P=0.009; t=3.96, P=0.001, respectively), and were found to be significantly correlated with the expression of PCNA in 21 patients with homogeneous astrocytomas (r=0.455, P=0.038; r=0.633, P=0.002, respectively). We conclude that (1)H-MRS may be a valuable method for predicting preoperatively the degree of malignancy of homogeneous astrocytomas by enabling the calculation of the Cho/NAA and Cho/Cr ratios in vivo, and indirect evaluation of the tumor proliferative potential and prognosis, which are not available using conventional magnetic resonance imaging (MRI).

Pathobiology of Hemophilic Synovitis II: Synovial Cell Proliferation.

Hemophilia is a genetic disease due to the deficiency of blood coagulation factor VIII or IX. Bleeding is common, especially into joints where a proliferative synovitis develops resulting in a debilitating arthritis, hemophilic arthropathy. The pathogenesis of blood-induced hemophilic synovitis (HS) is poorly understood. Repeated episodes of bleeding induce synoviocyte hypertrophy and hyperplasia, an intense neovascular response and inflammation of the synovial membrane. The component(s) in blood that initiates these changes is (are) not known, although iron is often proposed as one possibility. Previously, we reported that iron promotes the proliferation of human synovial fibroblasts and increases c-myc expression in vitro (Blood 2002; 100(3)912–6). Here, we describe the proliferative effects of joint bleeding following traumatic hemarthrosis in a murine model of severe, human hemophilia A. Controlled, blunt trauma to the right knee joint consistently resulted in joint swelling due to a combination of bleeding and inflammation. The left, control knee was sham injured and remained normal for the duration of the experiment. Hemarthrosis resulted in acute morbidity evidenced by inactivity, weight loss and immobility. Hemosiderin was found in the synovial membrane of the right knees only. The numbers of synovial cell layers present in the membrane of the right (injured) knee increased during the experiment (figure). Expression of Ki67 in the nucleus, a marker of cell proliferation, confirmed the increase in synovial cell proliferation in membranes from the right (injured) knees. Taken together these data support the notion that iron causes aberrant gene expression and is, at least in part, responsible for the pathological findings observed in the joints of patients following bleeding and contributes to the development of hemophilic synovits. [Display omitted]

Lipid class dynamics during development in early life stages of shortbelly rockfish and their application to condition assessment

Lipid class dynamics and the relationship between weight and length were analysed during early life stage (ELS) development in wild populations of shortbelly rockfish Sebastes jordani to investigate their utility in a condition or nutritional status assessment. Analyses from more than 3000 field‐captured shortbelly rockfish indicated little variation in weight for a given length and provided limited application in the assessment of condition. The fractionation of total lipids into individual classes revealed trends in lipid metabolism throughout development. These trends were described best using a stage‐specific regression model, since Sebastes show defined early life history transitions. Among developmental stages, triacylglycerols (TAG) and polar lipids (PL) were the dominant lipid classes and cholesterol (CHOL), sterol/wax esters, and nonesterified fatty acids were found in lower concentrations. In the preflexion stage, low concentrations and constant levels of TAG along with the combined influence of endogenous and exogenous sources of energy compromised the use of TAG as an index of nutritional status. However, during flexion through juvenile stages, TAG levels increased indicating an accumulation of energy reserves with development, thus providing a valid indicator of nutritional status in later stages. Large fluctuations in PL concentrations during development suggested complex metabolism which may be due to changes in cell volume and cell membrane proliferation with development as well as catabolism. CHOL declined in larval stages, then remained constant with increasing size through the juvenile stage, negating its use as a normalizer for variations of mass in a TAG/CHOL ratio prior to juvenile transformation. This study provides the first documentation of lipid dynamics during early life stages following parturition in a marine viviparous teleost.