Other Methods at Profil

Supporting investigational methods at Profil

• Anthropometric methods, including body mass index, waist circumference, hip circumference, waist-to-hip ratio and waist-to-height ratio
• Analyses of biomarkers of glucose, liver, bone metabolism and many others
• Clarke’s Error Grid Analysis (EGA) for evaluating the clinical significance of differences in glucose readings obtained from a glucose measurement device and a reference glucose analyzer.
  
• Continuous glucose monitoring (CGM) for measuring glucose levels and alerting the user when critical ranges are entered or close.
  The currently available CGM systems measure glucose in the subcutaneous tissue through a small sensor needle that typically lasts for 3–7 days and sends a glucose value every 5 minutes through a connected transmitter to a receiver. The receiver displays the glucose value, time-profiles and trend information.
• Fatty Liver Index (FLI) measurements for prediction of hepatic steatosis. 
  FLI is an algorithm developed and validated as a predictor for hepatic steatosis. For more precise quantification of steatosis, MRI-scans or MRI-spectroscopy have to be employed (see below). This can be offered in collaboration with partner institutions. Application of further indices for assessment of hepatic fibrosis (e.g. FIBROTEST, FIB-4 test) can also be employed.
  
• Fundus photography, using a non-mydriatic retinal camera, for the assessment of diabetic retinopathy (established collaboration with ophthalmologist).
• Gene expression profiling to provide a comprehensive overview of mRNA expression levels in defined organs, tissues and cells. This technique can be used to investigate pharmacodynamic effects, such as any influence on energy metabolism, insulin signaling and tissue variability. It is also useful for differentiating between responders and non-responders and for finding early phase indications of novel modes of action, benefits or safety issues.
• Glycemic Index (GI) for the quantification of the effects of food products on blood glucose levels
  GI is expressed as the incremental area under the blood glucose response curve of a 50 g carbohydrate portion of a test food in relation to the response of a 50 g carbohydrate portion from a standard food (usually a glucose solution or white bread). At Profil, GI-tests are performed according to FAO/WHO standards.

• Holter monitoring
  Profil is equipped with state-of-the-art holter monitoring devices allowing the continuous recording of ECG and/or blood pressure over 24 hours or longer.

• HOMA for the quantification of insulin sensitivity (%S) and ß-cell function (%B) using fasting values of insulin and glucose
  Note that this technique has severe limitations compared to more sophisticated methods such as the glucose clamp technique. The test only looks at the fasting state rather than the insulin-stimulated state. Furthermore, it relies on adequate insulin secretion in the tested population and cannot distinguish between hepatic and peripheral insulin sensitivity. HOMA describes insulin sensitivity and ß-cell function by a set of empirically derived nonlinear equations.
• In vivo and ex vivo analysis of mitochondrial activity for the determination of fatty acid oxidation, surrogates of mitochondrial activity and tissue-specific ATP synthesis
• Insulin Suppression Test (IST) for the direct estimate of insulin resistance. This test functions by suppressing endogenous insulin release through the continuous infusion of epinephrine and propranolol. Likewise, insulin and glucose are infused, so that after steady state is reached, insulin plasma levels are (theoretically) similar in all subjects. Therefore, the height of the steady-state plasma glucose level provides a direct estimate of insulin resistance.
• Insulin Tolerance Test (ITT) for rough assessments of insulin sensitivity
  This crude method measures the slope of decline in blood glucose concentrations after an intravenous insulin bolus. It can also be used as functional test for the hypothalamo-pituitary-adrenal (HPA) axis, i.e., it demonstrates the adequacy of the anti-hypoglycemic response.
• Intima Media Thickness (IMT) measured by means of high-resolution ultrasound
• Lipolysis measurements
  Whole body lipolysis can be addressed by measuring the dilution of isotope-labeled glycerol in the plasma. The insulin sensitivity of the whole body largely reflects the sensitivity of the adipose tissue to the suppression of lipolysis by insulin and can be addressed by combining a two- or multiple-step low-dose insulin infusion with the infusion of labeled glycerol and a euglycemic glucose clamp.
• Microdialysis for continuous quantification of free analytes in the extracellular space of e.g. fat tissue
  This minimally invasive method uses a microdialysis catheter that consists of a shaft with a semi-permeable membrane that is continuously perfused with a perfusate. After insertion into the tissue, small molecules can cross the membrane by passive diffusion. The concentration of the analyte in the perfusate is proportional to the concentration in the tissue, but is also dependent on other factors, such as molecular size and flow rate. These factors influence the recovery of the analyte.
  In addition to subcutaneous microdialysis, Profil has experience with intravenous microdialysis techniques that allow the continuous quantification of analytes in the blood without any (cellular) blood loss and without a substantial time delay.
• Magnetic Resonance Imaging – Proton Density Fat Fraction (MRI-PDFF) is the most reliable way to assess liver fat content. We offer this service through a collaboration with an external partner.
• Magnetic Resonance Spectroscopy (MRS) is used to assess hepatic metabolism. In particular, it can quantify liver glycogen. We offer this service through a collaboration with an external partner.
• Oral glucose tolerance test (OGTT) for screening for diabetes or prediabetes or assessing drug glucose lowering activity.The OGTT is a comparably simple test to assess glucose handling and glucose lowering action. Modeling can be used to derive insulin sensitivity parameters.
• Plasma volume measurement
  Plasma volume may be measured using a dye dilution method with, for example indocyanine green (ICG). PV is calculated based on the theoretical concentration of ICG in plasma at T = 0 (C0). C0 is calculated by monoexponential extrapolation of the light absorption curve (spectrophotometry) of the ICG concentration curve (HPLC) resulting from the respective time points measured.
• Renal function: There are various routine formulas to estimate Glomerular Filtration Rate, including CKD-EPI 2021. We have iohexol clearance established when a more precise measurement of glomerular filtration is required. As to imaging, MRI kidney biomarkers include arterial flow, velocity, resistance markers, as well as perfusion, diffusion and oxygenation markers and kidney parenchyma volume.
• Telemetry
  Allows continuous supervision of ECG and oxygen saturation in up to 28 people at the same time. The telemetry covers our whole clinic including the clamp facilities. If needed, the telemetric recordings can be downloaded and be made available to our clients.
• Tonometry or Applanation tonometry for accurate, reproducible, non-invasive assessment of the central pulse pressure (PP) waveform
• Venous Occlusion Plethysmography of the forearm to determine blood flow in mL/min (mostly reflecting microvascular function)
• Visual analogue scale (VAS) for the determination of nearly all continuous non-dichotomic patient-reported outcomes, e.g., subjective characteristics or attitudes like pain, appetite and satiety  
  Profil has developed a proprietary, fully validated and easy-to use digital system for the quantification of the VAS response of subjects.