In Vivo quantitative mapping of cardiac perfusion in rats using a noninvasive MR spin-labeling method

Measurement of myocardial perfusion is important for the functional assessment of heart in vivo. Our approach is based on the modification of the longitudinal relaxation time T1 induced by magnetic spin labeling of endogenous water protons. Labeling is performed by selectively inverting the magnetization within the detection slice, and longitudinal relaxation is measured using a fast gradient echo MRI technique. As a result of blood flow, nonexcited spins enter the detection slice, which leads to an acceleration of the relaxation rate. Incorporating this phenomenon in a mathematical model that describes tissue as two compartments yields a simple expression that allows the quantification of perfusion from a slice-selective and a global inversion recovery experiment. This model takes into account the difference between T1 in blood and T1 in tissue. Our purpose was to evaluate the feasibility and reproducibility of this technique to map quantitatively myocardial perfusion in vivo in rats. Quantitative maps of myocardial blood flow were obtained from nine rats, and the reproducibility of the technique was evaluated by repeating the whole perfusion experiment four times. Evaluation of regions of interest within the myocardium yielded a mean perfusion value of 3.6 ± .5 ml min^?1 g^-1 over all animals, which is in good agreement with previously reported literature values.     

Quantitative relation of Renshaw cell discharges to monosynaptic reflex height

Summary If Renshaw cells are fired by monosynaptically excited motoneurons the number of repetitive discharges of the interneurons increases in direct proportion to the height of the monosynaptic reflex, i.e., to the number of motoneurons in the discharge zone. The average slope is 10.6±2.9.These investigations were supported by the Deutsche Forschungsgemeinschaft (Sonderforschungsbereich 33 Nervensystem und biologische Information, Göttingen).     

Alpha-feto-protein (AFP) and human chorionic gonadotropin (HCG) as biochemical markers of intracranial germ-cell tumours

Summary A 17-year-old male with an intracranial endodermal sinus tumour and chorio-carcinoma, had elevated AFP and HCG levels. During therapy, these levels returned to normal. The importance of both AFP and HCG for the diagnosis and treatment of certain cranial tumours in childhood is discussed.     

The pharmacokinetics of papaverine and its bioavailability from a sustained-action preparation]

The serum levels of intravenously and orally given papaverine were determined in healthy, fasting beagles. The bioavailability of the drug was assessed in the same animals following single administration of the sustained-action preparation Panergon (papaverine-hydrochloride). Based on a one-compartment model, the time of invasion, the half-life of elimination, the volume of distribution and the absorption rate of papaverine were calcualted. A comparison of the areas under the concentration curves shows the complete bioavailability of the papaverine contained in Panergon.     

Disinhibition der Extensor-Motoneurone nach intercolliculärer Dezerebrierung

Zusammenfassung Trotz kontinuierlicher Anaesthesie und Unterbrechung der Gamma-Spindelschleife löst die natürliche oder elektrische Reizung homonymer Ia-Afferenzen mit konstanter Stärke nach intercolliculärer Dezerebrierung an Extensor-Motoneuronen regelmäßigere Antworten, Verkürzung der Reflexzeit, Zunahme der Entladungsfrequenz, Verstärkung der post-tetanischen Potenzierung und Rekrutierung aus. Da der Grad der recurrenten Hemmung abnimmt, schließen wir, daß die gesteigerte Erregbarkeit der Extensor-Motoneurone im Zustand der Dezerebrierung mit Disinhibition verbunden ist. Die mit einem konstanten Quantum reflexwirksamer Afferenzen erhaltenen Resultate sprechen für unsere Annahme, daß Spastizität nicht hauptsächlich auf fusimotorischer Enthemmung beruht.

---

Disinhibition of extensor motoneurones after intercollicular decerebration

Summary Even with continued anesthesia and interrupted gamma-loop intercollicular decerebration leads in extensor motoneurones (excited by electrical or natural stimulation of homonymous Ia-afferents with constant strength) to the following phenomona: more regular responses, shortening of reflex time, increase of discharge frequency, enhancement of post-tetanic potentiation, and recruitment. Because the degree of recurrent inhibition is diminished we conclude that the higher excitability of extensor motoneurones in the decerebrate state is correlated with disinhibition. Furthermore the results obtained with the afferent input for motoneurones kept constant favour our assumption that spasticity is not based merely on the release of fusimotor activity.

     

Flow cytometric DNA ploidy in salivary gland tumours

This study on 279 tumours of the salivary glands was conducted to analyse whether the assessment of DNA ploidy by flow cytometry may assist histopathology in discriminating benign from malignant types of tumours. The group of benign tumours included 164 pleomorphic adenomas, 51 Warthin's tumours, 7 basal cell adenomas, 2 lipomas as well as 5 other different tumours. All of the 229 benign tumours were diploid. The malignant tumours consisted of 18 adenoid cystic adenomas, 10 mucoepidermoid carcinomas, 5 acinic cell carcinomas, 5 carcinoma in pleomorphic adenoma as well as of 12 other malignancies belonging to 7 different tumour entities. Twelve of 50 malignant salivary gland tumours were aneuploid. There was no significant relationship between the DNA ploidy status and histopathological grading, lymph node metastasis and local recurrence development, respectively. In three cases which initially were taken for pleomorphic adenomas by routine histological examination, aneuploid cell populations exposed by DNA flow cytometric analysis gave rise to a closer inspection of the suspect lesions. Examination of consecutive slides actually revealed small assemblies of carcinoma cells that required a final diagnosis as non-invasive carcinoma in pleomorphic adenoma. The most obvious value of DNA flow cytometry in salivary gland tumours is thus its contribution to assist histopathology in identifying potentially malignant lesions.