The effect of stem cell proliferation regulators demonstrated with an in vitro assay

Spleen colony formation after transplantation of bone marrow cells into irradiated mice has been used as an assay for hematopoietic stem cells (CFU-S), but has serious limitations intrinsic to an in vivo assay. In this report we describe experiments using an in vitro clonogenic assay that is especially suitable for studies of stem cell regulation as defined growth factors and normal untreated bone marrow can be used. We have demonstrated that the colony-forming cells have proliferative properties in common with CFU-S and respond to specific proliferation regulators previously detected using the spleen colony assay.     

Magnetic resonance imaging of the masseter muscle of the rabbit

Abstract – Gross anatomy of the masseter muscle was studied in eight rabbits using a 2.34 tesla MRI-device. Anatomy was displayed and assessed consistent with previous dissectional findings. It is concluded that MRI, applied as described in the present study, is suitable for assessment of masseter morphology in experimental studies on the rabbit.     

Blackening of unprotected dental X-ray films due to scattered radiation

Abstract — Unexposed films awaiting exposure as well as exposed films awaiting processing are subjected to scattered radiation if kept unprotected in the dental X-ray clinic. The purpose of the present study was to analyze the influence of various storing principles, film speed, and distance from X-ray source upon the degree of film blackening. Test films were subjected to scattered radiation from 150 exposures. Maximum additional blackening (0.27 D) was recorded for type E films not protected by lead foil at the shortest distance studied (55 cm). As a distance of 200 cm blackening was reduced to 0.02 D and could be futher reduced by utilizing the inherent protective effect of the lead foil. It is concluded that if dental X-ray films not in use are kept at a distance of 200 cm from the X-ray source and protected by lead foil additional blackening due to scattered radiation is negligible and further protective precautions are unnecessary.     

Primary structure,spectroscopic and inhibitory properties of a two-chain trypsin inhibitor from the seeds of charlock (Sinapis arvensis L), a member of the napin protein family

A protein with inhibitory activity toward trypsin has been isolated from Sinapis arvensis L (charlock). It has a molecular weight of 15500 and consists of two chains connected by disulfide bonds. The amino acid sequence was determined and showed that it belongs to the napin family of storage proteins. CD studies showed an α-helix content of 12% and a β-structure of about 50%.     

PET studies of net blood-brain clearance of FDOPA to human brain: age-dependent decline of [18F]fluorodopamine storage capacity.

Conventional methods for the graphical analysis of 6-[(18)F]fluorodopa (FDOPA)/positron emission tomography (PET) recordings (K(in)(app)) may be prone to negative bias because of oversubtraction of the precursor pool in the region of interest, and because of diffusion of decarboxylated FDOPA metabolites from the brain. These effects may reduce the sensitivity of FDOPA/PET for the detection of age-related changes in dopamine innervations. To test for these biasing effects, we have used a constrained compartmental analysis to calculate the brain concentrations of the plasma metabolite 3-O-methyl-FDOPA (OMFD) during 120 mins of FDOPA circulation in healthy young, healthy elderly, and Parkinson's disease subjects. Calculated brain OMFD concentrations were subtracted frame-by-frame from the dynamic PET recordings, and maps of the FDOPA net influx to brain were calculated assuming irreversible trapping (K(app)). Comparison of K(in)(app) and K(app) maps revealed a global negative bias in the conventional estimates of FDOPA clearance. The present OMFD subtraction method revealed curvature in plots of K(app) at early times, making possible the calculation of the corrected net influx (K) and also the rate constant for diffusion of decarboxylated metabolites from the brain (k(loss)). The effective distribution volume (EDV(2); K/k(loss)) for FDOPA, an index of dopamine storage capacity in brain, was reduced by 85% in putamen of patients with Parkinson's disease, and by 58% in the healthy elderly relative to the healthy young control subjects. Results of the present study support claims that storage capacity for dopamine in both caudate and putamen is more profoundly impaired in patients with Parkinson's disease than is the capacity for DOPA utilization, calculated by conventional FDOPA net influx plots. The present results furthermore constitute the first demonstration of an abnormality in the cerebral utilization of FDOPA in caudate and putamen as a function of normal aging, which we attribute to loss of vesicular storage capacity.     

Renal hypomagnesaemia in human diabetes mellitus: its relation to glucose homeostasis

Abstract. Interrelations between magnesium and glucose metabolism were studied in 215 insulin-treated diabetic out-patients aged 7–70 years. All had normal serum creatinine concentrations (below 115 μmol/l) and none had other diseases or received drugs known to interfere with mineral metabolism. A definite hypomagnesaemia (< normal mean —2 SD) and hypermagnesiuria (> normal mean + 2 SD) occurred in 38.6% and 55% of the patients. In the presence of hypermagnesiuria the serum magnesium concentration was inversely correlated to the urinary magnesium excretion rate ( R =–0.23, P <0.02). Serum magnesium correlated inversely with both fasting blood glucose ( R =—0.32, P <0.001) and the urinary glucose excretion rate ( R =–0.22, P <0.005). The urinary magnesium excretion rate correlated directly with the same variables ( R = 0.27, P <0.001 and R = 0.58, P <0.001, respectively). These data indicate that the net tubular reabsorption of magnesium is decreased in diabetic patients in presence of hyperglycaemia, leading to hypermagnesiuria and hypomagnesaemia.     

Therapeutic monitoring of new antipsychotic drugs

Typical antipsychotic drugs qualify for therapeutic drug monitoring (TDM) primarily for the following reasons: control of compliance and avoidance of extrapyramidal side effects by keeping chronic exposure to minimal effective blood levels. For the atypical antipsychotic clozapine, drug safety is another reason to use TDM. With regard to the new antipsychotics risperidone, olanzapine, quetiapine, amisulpride, ziprasidone, and aripiprazole, which have been introduced in the clinic during the last few years, the rationale to use TDM is a matter of debate. Positron emission tomography (PET), which enables measurement of the occupancy of dopamine D2 receptors, revealed that receptor occupancy correlated better with plasma concentrations than with doses of the antipsychotics. Regarding plasma levels related to therapeutic effects, optimal concentrations have been established for clozapine (350-600 ng/mL), risperidone (20-60 ng/mL), and olanzapine (20-80 ng/mL) but not for the other new antipsychotics. Studies that included analyses of drug levels in blood reported mean concentrations of 68 ng/mL for quetiapine and 317 ng/mL for amisulpride under therapeutic doses of the antipsychotic drugs. For ziprasidone or aripriprazole, data on therapeutic drug concentrations are so far lacking. In conclusion, evidence is growing that TDM may improve efficacy and safety in patients treated with the new antipsychotic drugs, especially when patients do not respond or develop side effects under therapeutic doses. The few reported investigations, however, need to be confirmed and extended.