First Trimester Development of the Human Nigrostriatal Dopamine System

The aim of the present study was to characterize the morphological and neurochemical differentiation of mesencephalic dopaminergic neurons in human embryos, derived from elective first trimester abortions. Embryonic brain tissue was taken for analysis of tyrosine hydroxylase (TH) by immunohistochemistry and Western blot, and for analysis of endogenous dopamine (DA) content using HPLC-ED. TH expression was first detected at 3.5 weeks of gestational age (Carnegie stage 11) by immunohistochemical staining of the primordial sympathetic trunk along both sides of the neural tube. In sagittal sections of the intact 4.5-week-old embryo, a small, distinct population of rounded, densely packed TH-immunoreactive perikarya with short primary processes was seen in the midbrain. During the latter half of the first trimester, the number of TH-stained cells as well as the length and number of axonal processes projecting toward and into the developing neostriatum increased rapidly. At the end of the first trimester, varicose fibers could be detected in the striatal anlage. In order to verify that TH was the antigen recognized by the antibodies used for immunohistochemistry on human tissue specimens, mesencephalic tissue of 5–10 weeks gestation was analyzed by Western blot technique. A single, homogeneous band with the apparent molecular weight of approximately 60 kDa was clearly detected at 5 weeks of age. The amount of TH/mg total protein increased at least 10-fold between 5–10 weeks of gestation. For comparison, the mesencephalon and the forebrain/basal ganglia were analyzed for endogenous DA content using HPLC-ED. DA was first detected at 5.5 weeks of gestational age in both mid- and forebrain, and DA levels were found to increase exponentially from 7 to 7.5 weeks of age, reaching 4–5.5 ng DA/mesencephalon and 50–75 ng DA/g caudate nucleus–putamen anlage at the end of the first trimester. Together, morphological and biochemical data presented here constitute evidence for a very early appearance, migration, and differentiation as well as functional development of human mesencephalic dopaminergic neurons and their projections into target areas during the first trimester.     

Inhibition of melanoma cell directional migration in vitro via different cellular targets

Abstract In malignant melanoma active movement of cancer cells is considered to be essential for tissue invasion. Various mechanisms, such as the Ca²⁺-calmodulin-proteinkinase C cascade or G-protein-dependent processes are considered to play a role in tumor cell functions. The assay of directional migration, combined with computer-assisted image analysis, was used to evaluate the antimigratory efficacy of drugs interfering with different steps of signal (ransduction pathways. Treatment with different compounds showed a more or less concentration-dependent reduction of migration rates: The Ca²⁺-channel blockers verapamil and devapamil showed a slight reduction of molility. The effect was more pronounced when the calmodulin antagonist flunarizine was used or the proteinkinase C inhibitors dequalinium, tamoxifen and H-7 were applied. A marked inhibition of molility was found with the G-protein antagonist L 651582. Thus, our results indicate that different signal transduclion pathways are involved in the regulation of directional migration of K1735-M2 melanoma cells.     

Effects of sinusoidal whole-body vibration on the lumbar spine: the stress-strain relationship

Summary The aim of this experimental study was to estimate the strain in the lumbar spine due to whole-body vibration (WBV). Four male subjects were exposed to vertical sinusoidal WBV with frequencies ranging from 1 to 15 Hz at two intensities (I₁ = 1.5 ms^–2 rms; I₂ = 3.0 ms^–2 rms). The compressive forces acting on the disc L3-4 during the extreme values of acceleration were predicted on the basis of anthropometric data, EMG of back muscles and the acceleration of the upper trunk, using a simple biomechanical model. The estimated mechanical activity of back muscles was not able to protect the spine under many exposure conditions. The highest compressive forces were predicted for WBV with 7.5, 8 and 4.5 Hz. The results suggest the possibility of fatigue failures at the endplates of lumbar vertebrae after intense long-term exposure to WBV.The authors gratefully acknowledge the help and assistance of G. Menzel, R. Vizcaino, and A. Weissmüller     

CCK-2/gastrin receptor-targeted tumor imaging with (99m)Tc-labeled minigastrin analogs.

The aim of this study was to evaluate 3 new (99m)Tc-labeled minigastrin analogs modified with open chain tetraamines at the N-terminus for their suitability in the CCK-2/gastrin-R-targeted imaging of tumors (CCK-2/gastrin-R = cholecystokinin subtype 2/gastrin receptor). METHODS: The [(D)Glu(1)]minigastrin sequence was assembled on the solid support and the respective tetraamine precursors coupled at the N-terminus. Purified peptide conjugates were labeled with (99m)Tc under alkaline conditions. Saturation binding experiments were performed for (radio)metallated peptides [(99m)Tc/(99g)Tc]Demogastrin 1-3 in rat acinar pancreatic AR4-2J cell membranes. Internalization was studied in AR4-2J cells at 37 degrees C. Radiopeptide stability was tested in murine plasma, urine, and kidney homogenates. Tissue distribution of the peptides was compared in healthy mice and athymic mice bearing AR4-2J tumors. RESULTS: Peptide conjugates were obtained in 10%-30% overall yields by solid-phase techniques. Radiolabeling afforded >98% pure [(99m)Tc]Demogastrin 1-3 species in specific activities of approximately 37 GBq/mumol. Radiopeptides retained a high affinity for the CCK-2/gastrin-R in vitro (50% inhibitory concentration values of approximately 1 nmol/L) and internalized rapidly in CCK-2/gastrin-R-positive cells. After injection in mice they displayed rapid, high, and specific localization in the CCK-2/gastrin-R-expressing tissues (stomach and AR4-2J tumor) and were excreted from the body via the kidneys in the form of hydrophilic metabolites. CONCLUSION: The promising characteristics of [(99m)Tc]Demogastrin 1-3 both in vitro and in animal models illustrate their suitability for CCK-2/gastrin-R-targeted tumor imaging. These qualities could be confirmed for [(99m)Tc]Demogastrin 2, which provided excellent delineation of tumor deposits in a first patient with metastatic medullary thyroid cancer.     

Prognostic evaluation of specific cutaneous infiltrates in B-chronic lymphocytic leukemia

The relationship between numerous histologic variables and survival was investigated in 54 consecutive lesions of specific skin infiltrates of B-cell chronic lymphocytic leukemia (B-CLL) from 27 patients (16 males and 11 females, mean age 65 years, range 42–83 years). All patients were followed for up to 204 months or until death. Histopathologically, the infiltrates showed a patchy perivascular (35%), diffuse (31.5%), nodular (31.5%) or band-like (1.9%) pattern. In 28% of the cases, an admixture of reactive cells within the infiltrate including eosinophils, histiocytes, neutrophils and plasma cells was observed. Cytomorphologically, small B-lymphocytes with condensed chromatin predominated in most infiltrates. However, some biopsies showed a small but significant number of medium- or large-sized neoplastic cells of the B-lymphocyte lineage with variable cytomorphological features. In a multivariate analysis, several histologic parameters within the infiltrates were found to show a significant association with long survival, namely, an infiltrate of moderate density, a nodular pattern, involvement of the lower dermis only, and presence of predominantly small B-lymphocytes (more than 95%) with condensed chromatin. Histologic variables that independently correlated with relatively short survival included an infiltrate of severe intensity, a diffuse pattern, epidermal changes (especially acanthosis and ulceration), medium-sized and large B-lymphocyte (more than 5%), and reactive cells within the infiltrate (neutrophils, eosinophils, and plasma cells). Overall analysis of our results showed two histologic patterns with a significant prognostic impact (p<0.01; z=5.4). Pattern I (33 biopsies) correlated with relatively long survival (2-year survival rate; 97%) and consisted of infiltrates showing predominantly small B-lymphocytes (more than 95%) without reactive cells or epidermal changes. Pattern II (21 biopsies) indicated short survival (2-year survival rate; 49%) and included all the rest of the biopsies i.e., infiltrates with medium- and large-sized B-lymphocytes (more than 5%), admixture of reactive cells, and epidermal changes. Results from our study suggest that histologic features in specific skin infiltrates of B-chronic lymphocytic leukemia may be helpful in identifying prognostically different subgroups of patients and planning therapeutic schedules.     

Implantable Micropump System for Augmented Liver Perfusion

Liver cirrhosis, a worldwide health problem, decreases the blood flow through the liver. This in turn leads to dangerous portal hypertension and decreased metabolic function within the liver. To improve this situation, a new concept is proposed which involves introducing a microaxial blood pump into the portal vein. This device is intended to increase blood flow through the liver and to enhance hepatic function. Furthermore, high pressures will be reduced to physiological levels. The microaxial pump with its single stage impeller is powered by a proximally integrated microelectric motor. The pump unit is completely immersed within the blood vessel. Heat caused by electrical and mechanical losses will be transported into the blood. In vitro optimization of the pump design was accomplished using both hydraulic and hemolysis tests.