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PubMed2026

[Laryngeal squamous cell carcinoma-derived exosomes promote neuronal axonal growth by remodeling the neural microenvironment].

Objective: Perineural invasion (PNI) is a critical determinant of poor prognosis in laryngeal squamous cell carcinoma (LSCC), but its underlying mechanisms remain unclear. This study aimed to investigate whether LSCC-derived exosomes induce axonal growth by delivering neuroactive molecules, thereby contributing to tumor perineural invasion. Methods: Clinical data from the laryngeal cancer cohort of The Cancer Genome Atlas Head and Neck Squamous Cell Carcinoma (TCGA-HNSC) dataset were analyzed. Propensity score matching (PSM) and Cox regression were used to evaluate the prognostic value of nerve density, and these findings were validated using 35 pairs of laryngeal cancer and adjacent normal tissue specimens collected at Yantai Yuhuangding Hospital between 2022 and 2026 to assess neural morphological changes. Exosomes were isolated from the human LSCC cell line AMC-HN-8, characterized by quality-control assays, and co-cultured with PC12 cells. A rescue experiment using GW4869, a specific inhibitor of neutral sphingomyelinase, was performed to confirm the exosome-dependent effect. Neurite outgrowth was evaluated by immunofluorescence, and the expression of axonal growth-related genes was measured by RT-qPCR. Targeted metabolomics was employed for the absolute quantification of neuroactive metabolites within the vesicles and for pathway enrichment analysis. Results: After PSM adjustment, high nerve density was identified as an independent poor prognostic factor in LSCC patients (HR=2.10, P=0.035), with particularly pronounced prognostic value in the early-stage node-negative (N0) subgroup (HR=4.07, P=0.001). Pathological sections showed high expression of the neural markers βIII-tubulin and PGP9.5 in LSCC tissues (βIII-tubulin: t=2.234, P<0.05; PGP9.5: t=2.575, P<0.05). Exosomes were successfully isolated from AMC-HN-8 cells and passed quality control. In vitro assays showed that LSCC-derived exosomes significantly promoted neurite extension and branching in PC12 cells (t=4.147, P<0.000 1) and upregulated core axonal growth genes, including GAP-43, NEFL, and NEFM (GAP-43: t=3.698, P<0.05; NEFL: t=5.113, P<0.01; NEFM: t=5.263, P<0.01); this effect was completely reversed by the exosome-release inhibitor GW4869 (t=3.535, P<0.001). Targeted metabolomics revealed a specific enrichment of 12 neurotransmitters and metabolites within LSCC exosomes, centered on glutamine (83.411 μmol/L, FC=1.88) and glutamate (18.461 μmol/L, FC=1.21), which were significantly enriched in signaling pathways such as "central carbon metabolism in cancer" and "glutamatergic synapse". Conclusion: Nerve density is a potential adverse prognostic factor in patients with LSCC. LSCC-derived exosomes can directly induce axonal growth in neuron-like cells, suggesting that tumor cells actively remodel the neural microenvironment and drive axonal growth through exosome-mediated long-range signaling.

Exosomes↗

PubMed2000

Quantitative analysis of gene amplification in insecticide-resistant Culex mosquitoes.

The amplification of carboxylesterase structural genes followed by their overexpression is the most common mechanism of resistance to organophosphorus insecticides in Culex mosquitoes. Most resistant Culex quinquefasciatus mosquitoes have co-amplified estalpha2(1) and estbeta2(1) genes. Recently, Southern, DNA dot-blot analysis and phosphorimaging technology were used to quantify the est gene copy number in aphids and mosquitoes. Although more accurate than autoradiography, this method relies on probe hybridization, which can be variable. We have directly measured gene and mRNA copy number by using real-time quantitative PCRs in mosquitoes. The acquisition of fluorescence from incorporation of the double-strand-specific dye SYBR GreenI into a PCR product once per cycle is used to provide an absolute quantification of the initial template copy number. Thus it has been possible to show that estalpha2(1) and estbeta2(1) are co-amplified approx. 80-fold in the genome of the resistant PelRR strain of C. quinquefasciatus. The two genes, although co-amplified in a 1:1 ratio, are differentially transcribed: the estbeta2(1) gene from this amplicon has greater transcription than estalpha2(1) in all individual mosquito larvae tested, with an average ratio of 10:1. Purified esterases from mosquito homogenates were found in a ratio of 3:1, which, combined with the quantitative mRNA data, suggests the operation of both transcriptional and translational control mechanisms to regulate the expression of the amplified genes in C. quinquefasciatus insecticide-resistant mosquitoes.

Animals↗

PubMed2000

[Magnetic tomography--new imaging techniques and future perspectives].

BACKGROUND: From the very introduction of MRI into medicine, the modality has presented the user a long list of theoretical tissue contrast parameters. The development of MRI has been aimed at turning these theoretical possibilities into practical options. MATERIAL AND METHODS: We give an overview of the new MRI techniques and perspectives for the future based on a literature search and our own experience. RESULTS: Today, the modality offers state-of-the-art anatomical details as well as visualisation of several functional parameters such as perfusion, diffusion, blood oxygen saturation, and tissue temperature. In the near future, MRI may provide absolute quantification of regional perfusion and rate of oxygen consumption in a clinical setting. New vascular and gastrointestinal contrast media will further increase the sensitivity and specificity of MRI. A continuous increase in imaging speed has made MRI capable of providing adequate "fluoroscopic" guidance during interventional procedures, and real-time diagnostic imaging is only few years ahead. INTERPRETATION: The spread of MRI installations will increase as a result of increasing demand for the best and least harmful diagnostic procedure. The main challenge to the MRI community will be to exploit the vast diagnostic possibilities.

Blood Circulation↗

PubMed2000

Immunoquantitation of FMO1 in human liver, kidney, and intestine.

To determine the level of FMO1 protein present in human liver tissues, a monospecific antibody was prepared and a sensitive Western blotting procedure with enhanced chemiluminescence detection was developed. Human FMO1, purified from insect cells expressing the recombinant protein, was used as a protein standard for absolute quantification. The average concentrations of FMO1 in microsomes prepared from human liver, kidney, intestine, and fetal liver were found to be <1, 47 +/- 9, 2.9 +/- 1.9, and 14.4 +/- 3.5 pmol/mg, respectively. Quantitation in intestinal microsomes was complicated by variable degrees of proteolytic degradation of FMO1, not seen in microsomes prepared from liver or kidney. Recombinant human FMO1 and detergent-solubilized human duodenal microsomes both metabolized p-tolyl methyl sulfide stereoselectively to the (R)-sulfoxide, indicating the expression of functional FMO1 in human intestine. The relatively high levels of immunoquantifiable FMO1 in human kidney and fetal liver complement our previous catalytic studies in these tissues, which also demonstrated preferential (R)-p-tolyl methyl sulfoxide formation. These data demonstrate a profound ontogenic change in expression of hepatic FMO1 in humans, such that in adult life FMO1 is exclusively an extrahepatic drug-metabolizing enzyme. The marked expression levels of FMO1 found in human kidney coupled to the high catalytic activity of this isoform toward a diverse array of sulfides and tertiary amines suggest the possibility that human renal FMO1 is a significant contributor to the metabolic clearance of drugs and other xenobiotics bearing these functionalities.

Adolescent↗

PubMed2000

Serial proton MR spectroscopy of contrast-enhancing multiple sclerosis plaques: absolute metabolic values over 2 years during a clinical pharmacological study.

BACKGROUND AND PURPOSE: The time courses of total creatine (Cr), N-acetylaspartate (NAA), choline (Cho), and myo-inositol have not previously been investigated in the follow-up of contrast-enhancing multiple sclerosis (MS) plaques. Therefore, over a period of 2 years, we compared the absolute concentrations of these metabolites between patients treated with a placebo or 15 +/- deoxyspergualin (DSG) and between clinical groups with relapsing-remitting or secondary-progressive MS. METHODS: Sixteen patients, recruited from a pharmacological study of DSG, and 11 healthy control subjects were investigated by a stimulated-echo acquisition mode sequence (TR/TE = 3000/20). The selected volume initially contained a contrast-enhancing plaque, which was followed up for a period of 2 years. RESULTS: In contrast-enhancing plaques, Cho was significantly elevated and showed a significant reduction after both 3 and 12 months. The initially normal Cr significantly increased between 3 and 12 months, and was negatively correlated with plaque volume on T1-weighted MR images. NAA initially showed normal values, a significant decrease at 1 month, and a slow recovery over 2 years. Myo-inositol did not show a clear tendency. The placebo group did not differ from the treated group, nor did the relapsing-remitting group differ from the secondary-progressive group. CONCLUSION: The contradictory time courses of Cr and NAA show that an absolute quantification in proton MR spectroscopy in MS is necessary to avoid a false interpretation of reduced NAA/Cr ratios. The increase in Cr is probably due to remyelination. The initial dip and later recovery of NAA seem to be related to diminishing edema and remyelination.

Adult↗

PubMed1992

[Positron emission tomography in cardiological diagnosis: principles and clinical application].

Positron emission tomography (PET) is an emerging new cardiac imaging modality which allows sophisticated tissue characterization using radiopharmaceuticals. This technique provides absolute quantification of regional tracer concentration using short-lived isotopes such as carbon-11, oxygen-15 and nitrogen-13, which can be easily incorporated in many compounds without changing their biological behaviour. These technical advantages are somewhat offset by the high cost of this technology which includes camera as well as on site cyclotron required for the preparation of radiopharmaceuticals. Recent clinical dates suggest that unique information can be obtained with PET. Using blood flow tracers in combination with PET, coronary artery disease can be detected and localized with high diagnostic accuracy. First studies comparing Tl-201 SPECT and PET in the same patient population indicate diagnostic superiority of PET. In combination with tracer kinetic models, regional myocardial blood flow can be quantitated and the functional significance of coronary artery stenosis defined by regional coronary reserve measurements. The assessment of regional glucose metabolism by PET with the tracer F-18 deoxyglucose has received wide clinical acceptance. Metabolic imaging in patients with advanced coronary artery disease allows the delineation of ischemically compromised but viable myocardium. Selection of patients for revascularization based on this scintigraphy tissue characterization has been shown to have a high predictive value for subsequent tissue recovery. Comparison of PET/FDG imaging with thallium-201 scintigraphy for assessment of tissue viability indicate that, in patients with fixed thallium-201 defects, additional diagnostic information can be obtained by this more expensive technology.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomyopathies↗

PubMed1991

[Localized nuclear magnetic resonance spectroscopy in vivo. Physical principles and quantitative problems].

Recent technological developments extended the use of nuclear magnetic resonance to clinical imaging (MRI), as well as to in vivo metabolic studies on tissues and organs by means of localized spectroscopy (MRS). The quantitative determination of absolute metabolic concentrations by in vivo MRS still represents a challenge for technological efforts and biochemical investigations. In fact, the different methodologies today available for spectral acquisition from localized regions within a body organ or pathological lesion should ideally lead to a complete suppression of signals from surrounding tissues, without any appreciable signal loss from the volume of interest. Accurate assessment of deviations of the real from the ideal case represents an essential requirement for either relative or absolute quantification of in vivo localized MR spectra. A review will be presented of the most utilized MRS methodologies, together with a discussion on their potentialities and limitations. Techniques have been classified according to the use of either r.f. (B1) and/or static magnetic field (B0) gradients. The last session will be devoted to the presentation of some results obtained in our laboratory on the use of a particular test-object (constructed at the Deft Institute of Technology) for assessing signal localization efficiency provided by a surface coil in a small scale MRS/MRI equipment (for in vivo biochemical studies on small animals). The surface coil was used in conjunction with a number of sequence (t1-90 degrees-acq; 1-D "chemical shift imaging"; "depth") of either square or adiabatic r.f. pulses. The results allow the selection, on a quantitative basis, of the most appropriate pulse sequence(s) to be used for metabolic studies on superficial experimental tumours (implanted s.c. in small animals), according to the mean area and thickness of the neoplastic lesion. The latter parameters can be non-invasively assessed by previous MRI analysis of the tumour. This study was carried out in the frame of the EC COMAC-BME Concerted Research Project on Tissue Characterization by MRS and MRI.

Animals↗

PubMed1986

Alterations of energy metabolism in the spontaneously hypertensive rat: a 31P nuclear magnetic resonance study.

We quantified high-energy phosphate metabolites in hypertensive hypertrophied and normal myocardium and monitored temporal changes using the non-invasive 31P nuclear magnetic resonance (NMR) spectroscopy. Hearts from 18 month spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto rats (WKY) were perfused with a phosphate-free buffer at 10 cc/min per g and paced at 240 beats/min on a modified Langendorff apparatus. Perfusion pressure, left ventricular pressure (LVP) and dP/dt were recorded and successive 31P NMR spectra were collected during a 24-min baseline period (oxygenated buffer), anoxia (N2-bubbled and glucose-free buffer) until a 70% fall in LVP occurred, and recovery. An aminomethylphosphonate standard, located within the LVP balloon, permitted absolute quantification of myocardial phosphate moieties (including inorganic phosphate (Pi), creatine phosphate (CP) and ATP). During perfusion, SHR hearts demonstrated higher coronary resistance but no significant differences in LVP or dP/dt. Spontaneously hypertensive rat hearts had lower CP, ATP and CP/Pi ratio and showed a faster fall in cardiac function during anoxia, associated with parallel rates of changes in the phosphate moieties.

Animals↗

PubMed1975

Measurement of absolute amounts of antigen-specific human IgE by a radioallergosorbent test (RAST) elution technique.

A technique for the absolute quantification of antigen-specific human IgE is described. It employs elution of a calculable amount of antigen-specific IgE from an allergosorbent-antibody complex by means of alkaline pH treatment, followed by measurement of the IgE content of the eluate with a modified radioimmunosorbent test (RIST). With this method IgE antibody directed against the benzylpenicilloyl determinant of penicillin (BPO) was measured quantitatively in sera from seven penicillin allergic patients. IgE specific for ragweed antigen E was measured in sera from 33 ragweed allergic patients. Values obtained for IgE anti-BPO ranged from 19 to 1806 ng/ml and comprised from 1.3 to 27.5% of total serum IgE. Values of IgE anti-antigen E ranged from 9 to 1807 ng/ml, comprising from 3 to 84% of total serum IgE. Excellent correlation (r = 0.99; p less than 0.001) was obtained for both antigen systems between values determined by the RAST elution technique and by simple RAST assay with interpolation from a reference serum of known specific IgE content as determined by the elution technique may be needed only for primary standardization of reference sera.

Allergens↗

PubMed1982

Absolute quantitation of radiotracer uptake in the lungs using a gamma camera.

A transmission-emission method for the absolute quantitation of Tc-99m in the lungs with a computerized gamma camera is described. The method requires no measurements of the linear attenuation coefficients of the lung and chest wall, or of their thickness. It yields results of acceptable accuracy for everyday clinical use and offers the great advantage of avoiding the use of a phantom. The method could be extended for the absolute quantification of Tc-99m agents in soft tissue and bone with errors of less than 10%.

Humans↗

PubMed1994

The cell blot assay in analysis of rat anterior pituitary cell secretion.

We have investigated the efficacy of the cell blot assay in analysis of the secretion of hormones and peptides from rat anterior pituitary cells. The dissociated cells are cultured on pieces of translucent polyvinylidene difluoride membrane, on which their secretory products are adsorbed and subsequently immunostained. The area and integrated optical density of the stained 'halo' surrounding individual cells is measured by microscopical image processing and the values for basal secretion of a particular hormone or peptide are compared with those after application of secretagogues or inhibitors. Our experiments tested established responses of dissociated rat anterior pituitary cells; in general, the results were as expected. Double immunoenzymatic staining could be used to show secretion of two products from the same or different cells in one preparation, and immunofluorescence with fluorescein- and/or rhodamine-labelled antibodies could be used instead of enzyme-linked immunolabelling. Optimal dilutions of immunoreagents were much higher than those used for immunocytochemistry on tissue sections. Although the cell blot assay does not provide absolute quantification, since some of the secreted product escapes into the medium, it is a relatively easy and economical way for morphologists to compare secretion from individual cells under varying conditions.

Adrenocorticotropic Hormone↗

PubMed1995

Comparative assessment of nine scatter correction methods based on spectral analysis using Monte Carlo simulations.

UNLABELLED: We compared nine scatter correction methods based on spectral analysis which process SPECT projections. METHODS: Monte Carlo simulation was used to generate histories of photons emitted from a realistic 99mTc phantom. A particular projection was considered. Information regarding the history, location and energy of the photons detected in this projection was analyzed to test the assumptions underlying each scatter correction method. Relative and absolute quantification and signal-to-noise ratio were assessed for each scatter corrected image. RESULTS: For the simulated data, two methods do not enable activity quantification. Among the methods requiring some parameters to be calibrated, the dual-energy window method shows the best compromise between accuracy and ease of implementation but introduces a bias in relative quantification. In this respect, a triple-energy window technique is more accurate than the dual-window method. A factor analysis approach results in more stable quantitative accuracy (error approximately 10%) for a wide range of activity but requires a more sophisticated acquisition mode (30 energy windows). CONCLUSION: These results show that a scatter correction method using spectral analysis can be used to substantially improve accurate quantification.

Humans↗

PubMed1993

New techniques in the pharmacokinetic analysis of cancer drugs. IV. Positron emission tomography.

Positron emission tomography is a powerful tool for the absolute quantification of injected positron emitting radiotracer concentration within tissues in vivo. Very detailed spatiotemporal data can be obtained without biopsy sampling. Most chemotherapeutic agents can be labelled with a positron emitter, and human tissue and tumour pharmacokinetics can be obtained non-invasively. Its main limitations are the inability to discriminate metabolites, the short half-life of the isotopes used and the specialized equipment required. Despite this, PET has the potential to make a major contribution in the study of the pharmacokinetics of anti-cancer drugs.

Antineoplastic Agents↗

PubMed1994

MR spectroscopy in clinical research.

MR spectroscopy (MRS) offers unique possibilities for non-invasive evaluation of biochemistry in vivo. During recent years there has been a growing body of evidence from clinical research studies on human beings using 31P and 1H MRS. The results indicate that it is possible to evaluate phosphorous energy metabolism, loss of neurones, and lactate production in a large number of brain diseases. Furthermore, 31P and 1H MRS may be particularly clinically useful in evaluation of various disorders in skeletal muscle. In the heart 31P MRS seems at the moment the most suitable for evaluation of global affections of the myocardium. In the liver 31P MRS appears to be rather insensitive and non-specific, but absolute quantification of metabolite concentrations and using metabolic "stress models" may prove useful in the future. The clinical role of MRS in oncology is still unclear, but it may be useful for non-invasive follow-up of treatment. Taken together, the evidence obtained so far certainly shows some trends for clinical applications of MRS. Methods are now available for the clinical research necessary for establishing routine clinical MRS examinations.

Bone Marrow Diseases↗

PubMed1993

[1H magnetic resonance spectroscopy in intracranial tumors and cerebral ischemia].

Image-guided localized proton magnetic resonance can now increasingly be used with clinical 1.5T MR systems. To fuel the discussion on whether spectroscopy will become a routine modality or whether it will remain a research tool, we report on our experience with a stimulated echo sequence in 60 patients harboring intracranial tumors and 79 patients suffering from various forms of cerebral ischemia. Spectroscopy was incorporated into a routine imaging protocol, and the parameters of TR = 1500 ms, TE = 270 ms were kept constant over a 3-year period. Relative changes in the metabolite concentrations were estimated from peak height and area calculations compared with the spectra of 66 normal volunteers. The spectra of the volunteers did not show significant interindividual variations, and there were no changes during photic stimulation in a subgroup of 6 volunteers. All tumor patients' spectra were significantly different from those of normal controls. Low grade gliomas showed decreased levels of N-acetyl-aspartate and some had elevated levels of lactate. Oligodendrogliomas had higher choline levels than astrocytomas. High grade gliomas had higher levels of lactate and lower N-acetyl-aspartate ratios. Meningiomas were characterized by absence of N-acetyl-aspartate, and some metastases showed a lipid signal at 1 ppm. Spectra of ischemic brain tissue were also abnormal, revealing lowered N-acetyl-aspartate and elevated lactate. The changes paralleled the severity of ischemia and pronounced abnormalities were associated with an inferior outcome. Further technical improvements, including absolute quantification of metabolite concentrations and smaller sensitive volumes, will allow direct monitoring of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

[Single-photon, emission-computed tomography (SPECT) in the diagnosis of epilepsy].

Regional cerebral blood flow can be measured using single photon emission computed tomography (SPECT). Hexamethyl propyleneamine oxime (HMPAO) is commercially available as a 99mTc-labeled tracer and has the advantage of fixing a blood flow pattern during its first passage through the capillaries. This can be used, for example, to evaluate a short-term ictal phase. With dedicated SPECT systems a spatial resolution of 5-8 mm can be achieved. Measurement using 133Xe allows absolute quantification of blood flow values, but the spatial resolution is lower. In about 50-70% of patients suffering from temporal lobe epilepsy a decreased blood flow in the focus can be visualized in the interictal phase. Ictally, focal hyperperfusion can be observed in most cases. The sensitivity and specificity of SPECT in the ictal phase are superior compared with interictal study. During the postictal phase a hyperperfusion of the anterior and mesial parts of the affected temporal lobe with simultaneous lateral hypoperfusion can often be demonstrated. At present, receptor SPECT has not yet reached clinical significance in the diagnosis of epilepsy.

Brain↗

PubMed1996

The potential of high-resolution positron emission tomography to monitor striatal dopaminergic function in rat models of disease.

The use of a recently commissioned small-diameter, high-resolution positron emission tomography (PET) to obtain a measure of specific binding of 3 carbon-11 labelled ligands in rat striatum is described. Using cerebellum as a reference tissue, compartmental modelling was used to obtain individual estimates of striatal binding potential (defined as the ratio of rate constants to and from the specifically bound compartment) for [11C]raclopride (D2 receptors), [11C]SCH 23390 (D1 receptors) and [11C]RTI-121 (dopamine transporter). The coefficients of variation in control, anaesthetized rats were of the order of 10%. Using two models of human disease, namely striatal injection of ibotenic acid to produce postsynaptic cell loss as in Huntington's disease, and 6-hydroxydopamine injection into substantia nigra pars compacta to mimic dopaminergic terminal loss in Parkinson's disease, marked reductions in binding potential were observed for the corresponding pre- or postsynaptic markers. When the regions of interest are so small as to be of the order of the spatial resolution of the system, factor such as spill over and partial volume negate absolute quantification of tissue radioactivity. Nevertheless, the use of PET to monitor relative changes in dopaminergic integrity should be considered as a viable complement to established in vivo microdialysis and post mortem techniques.

Animals↗

PubMed1996

Abnormalities of cell and mediator levels in bronchoalveolar lavage fluid of patients with mild asthma.

Increases in numbers and the activation state of inflammatory cells are typical findings even in patients with mild asthma. Periods of worsening inflammation are characterized by further changes, such as an increased number of eosinophils in patients with nocturnal asthma, an increased number of lymphocytes and basophils after allergen provocation, and an increased number of neutrophils after exposure to toluene diisocyanate. Correlations of bronchoalveolar lavage (BAL) findings with physiologic changes in patients with asthma are helpful but must be analyzed in the context of the difficulties in absolute quantification of cells and mediators in lavage. Correlations have been reported between BAL mast cells, eosinophils, and eosinophilic cationic protein and methacholine PC20 and FEV1. Correlations of other cell types or mediators with physiologic changes are either controversial (as with lymphocytes and their activation) or nonexistent (as with most mediators that have been measured). Ex vivo mediator production may be a useful measure. The ability to measure peripheral resistance directly at the site of inflammation may become an asset of the endobronchial instillation method. Causality can be proved only by selectively adding or removing certain inflammatory mediators through the use of leukotriene synthesis inhibitors, human grade eicosanoids, specific antagonists, agonists, and humanized antibodies. Of these examples, only leukotriene modulation has been evaluated with BAL in studies with human subjects. Whether inflammation and obstruction in patients with asthma result from the lack of certain mediators and/or an excess of others is unknown.

Asthma↗