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Technologies and Methods of MHH CRC Core Facility

Studies at the CRC Hannover benefit both from the high standard of clinical excellence and leading-edge diagnostic technologies and therapies at MHH and the highly competent and experienced team of the CRC Hannover.

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Echocardiography

Echocardiography is a noninvasive method that uses ultrasound to create images of the heart.

This method is free of risks and side effects and is used to examine the heart and its functions.

Clinical microdialysis

Microdialysis is a minimally invasive method for evaluating interstitial concentrations of endogenous molecules in the brain, skin, adipose tissue, skeletal muscle, heart, kidneys, and liver, while simultaneously estimating local blood flow.

It is also very useful for assessing tissue levels of medications in pharmacokinetic studies.

Measurement of body composition by bioimpedance analysis

Bioimpedance analysis is an easy way of measuring body composition. The impedance of cellular tissue depends on its water content and therefore differs between fat and other tissues. Using four electrodes, a minimal current of between 1 and 10 µA (too slight for patients to feel) is applied to the body.

The impedance is generally measured between a wrist and the ankle on the opposite side of the body. The voltage between the electrodes is measured for calculating total body water, which is in turn used to estimate the nonfat body mass and body fat.

Measurement of body composition by air displacement plethysmography

The BOD POD is an air displacement plethysmograph (ADP) that uses whole-body densitometry to determine body composition (fat vs. lean). Similar in principle to underwater weighing, this approach measures body mass (weight) using a very precise scale and body volume, while the patient is sitting inside the BOD POD.

After estimating body density, body composition is automatically calculated using validated formulas.

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Indirect calorimetry

Indirect calorimetry is used to estimate the type and rate of substrate utilization and energy metabolism. Carbon dioxide production and oxygen consumption during rest and steady-state exercise are measured and energy metabolism parameters calculated.

This noninvasive method is usually combined with other experimental methods in cardiometabolic studies.

Hyperinsulinemic euglycemic insulin clamping

This labor-intensive method is the gold standard for measuring insulin resistance. It requires considerable expertise and equipment, however.

Insulin and glucose are simultaneously infused in the patient, and insulin resistance is estimated based on the glucose infusion rate required to keep plasma glucose constant despite the induced hyperinsulinemia.

Frequently sampled intravenous glucose tolerance test (FSIGT)

FSIGT is another method for estimating insulin resistance. Body-weight-adjusted glucose and insulin doses are given to the patient intravenously and blood samples are taken at short intervals.

The insulin sensitivity index is estimated using computer modeling of the glucose and insulin dynamics. This approach has the advantage of being relatively simple compared to insulin clamping.

Tilt table test

The tilt table test is a procedure used to diagnose dysautonomia or syncope. It is also commonly used in cardiovascular studies to facilitate examinations of the sympathetic nervous system. The patient is strapped to a horizontal tilt table in a supine position. As soon as the blood pressure and heart rate have stabilized, the table is gradually tilted up to an erect head-up position, while continuously measuring the blood pressure and heart rate. Once the upright position is reached, if the patient feels well lower body negative pressure (LBNP) can be applied to increase the cardiovascular strain. The examination is terminated, if dizziness or lightheadedness occur.

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Microneurography

Microneurography is a sophisticated method for visualizing impulses in peripheral nerves that is used to study the sympathetic nervous system. A fine needle electrode is inserted into a peroneal nerve, usually of the right leg. The needle is connected to a high-gain recording amplifier.

The exact position of the electrode tip in the nerve is then minimally adjusted until the characteristic impulses of the sympathetic nervous system are discernible. During the examination, subjects are fully awake and able to cooperate in autonomic tests while impulses are recorded.

Other methods and equipment

The diagnostic procedures and equipment presented here are only examples. Please contact us to learn more about what is available.