Biomedical subjects

Jon Ramm-Pettersen

Publications and source records attributed to Jon Ramm-Pettersen.

3 recordsLinked to original sources

PubMed2006

[Endogenous Cushing's syndrome].

BACKGROUND: Untreated endogenous Cushing's syndrome is a serious condition with high morbidity and mortality. New diagnostic procedures make today's assessment more accurate. We describe which tests should be done when there is suspicion of the syndrome. Treatment options are mentioned. MATERIAL AND METHODS: The paper is based on current international literature and reflects the experience of the authors. RESULTS AND INTERPRETATION: Endogenous Cushing's syndrome is caused by elevated cortisol levels. The reason can be overproduction of ACTH or an adrenocortical pathology. It should be considered when combinations of symptoms like central obesity, proximal muscle weakness, striae and menstrual irregularities are seen. Osteoporosis and impotence are other important symptoms. Diagnosis of Cushing's syndrome is often challenging. Measurement of urinary free cortisol or overnight dexamethasone suppression test has usually been performed initially. Midnight salivary cortisol seems promising as an alternative. The final diagnosis is often made after a combined evaluation of dynamic tests. The first-line treatment of endogenous Cushing's syndrome is surgery.

Adrenocorticotropic Hormone↗

PubMed2005

Multipotent progenitor cells from the adult human brain: neurophysiological differentiation to mature neurons.

It was long held as an axiom that new neurons are not produced in the adult human brain. More recent studies have identified multipotent cells whose progeny express glial or neuronal markers. This discovery may lead to new therapeutic strategies for CNS disorders, either by stimulating neurogenesis in vivo or by transplanting multipotent progenitor cells (MPCs) that have been propagated and differentiated in vitro. The clinical application of such approaches will be limited by the ability of these cells to develop into functional neurons. To facilitate an understanding of mechanisms regulating neurogenesis in the adult human brain, we characterized the developmental processes MPCs go through when progressing to a neuron. Human tissue was harvested during temporal lobe resections because of epilepsy, and cells were cultured as neurospheres. Our findings demonstrate that at an early stage, these cells often stain with neuronal markers without possessing any functional neuronal properties. Over a period of 4 weeks in culture, cells go through characteristic steps of morphological and electrophysiological development towards functional neurons; they develop a polarized appearance with multiple dendrites, whereas the membrane potential becomes more negative and the input resistance decreases [from -48 +/- 10 mV/557 +/- 85 MOmega (n = 15) between days 7 and 11 to -59 +/- 9 mV/380 +/- 79 MOmega (n = 9) between days 25 and 38, respectively]. Active membrane properties were first observed on day 7 and consisted of a voltage-gated K+-current. Later in the second week the cells developed voltage-gated Ca2+-channels and fired small Ca2+-driven action potentials. Immature Na+-driven action potentials developed from the beginning of the third week, and by the end of the fourth week the cells fired repetitive action potentials with a completely mature waveform generated by the combined action of the voltage-gated ionic channels INa, IA and IK. After 4 weeks, the newly formed neurons also communicated by the use of GABAergic and glutamatergic synapses. The adult human brain thus harbours MPCs, which have the ability to develop into neurons and in doing this follow characteristic steps of neurogenesis as seen in the developing brain.

Adult↗

PubMed2004

Selective posterior cerebral artery amobarbital test: its role in presurgical memory assessment in temporal lobe epilepsy.

PURPOSE: To evaluate the efficacy and risk of complications of selective posterior cerebral artery (PCA) amobarbital anesthesia in memory assessment of patients with epilepsy under consideration for temporal lobe resection. METHODS: Thirty-two candidates for temporal lobectomy in whom conclusive memory assessment could not be obtained by the standard intracarotid amobarbital procedure were submitted to a selective PCA amobarbital test. A mean dose of 75 mg amobarbital was injected via microcatheter into the P2 segment of the PCA. Ten common objects were presented for naming and remembering while the anesthesia was judged efficient. After return to neurologic baseline, recall and recognition memory were assessed. RESULTS: In all of the 32 patients, angiography and PCA anesthesia were successfully accomplished without serious adverse events. All but one of the patients remained alert and cooperative for memory testing under the anesthesia, and 28 of these patients showed adequate memory capacity of the hemisphere contralateral to the side targeted for surgery. So far, 19 patients have proceeded to surgery, and no case of global amnesia or serious, material-specific memory impairment has resulted. Three patients failed the PCA test (fewer than 67% items correctly recognized) and were excluded from surgery, partly on the basis of the PCA test results, but also supported by an overall evaluation of all the diagnostic procedures used. CONCLUSIONS: The selective PCA amobarbital test appears justifiable when performed by interventional neuroradiologists and may significantly reduce the risk of erroneously excluding patients with epilepsy from temporal resection. Further corroboration of the safety of the procedure seems warranted.

Adolescent↗