Pituitary Folliculo-Stellate-Like Cells Stimulate Somatotroic Pituitary Tumor Growth in Nude Mice

A new cell line (TtT/GF) established from a murine pituitary thyrotropic tumor having characteristics similar to those of pituitary folliculo-stellate cell (FS cell) was implanted into nude mice together with cells from a rat pituitary somatotrophic tumor cell line (MtT/S) to determine whether the former enhances pituitary tumor growth. For as long as 2-3 mo after implantation, MtT/S cells implanted either alone or together with fibroblasts formed either no tumors or only very small tumors in the nude mice. In contrast all of the nude mice that had received MtT/S cells implanted together with TtT/GF cells developed large tumors. Furthermore, the mice bearing the MtT/S and TtT/GF implants showed a significantly higher body weight and serum growth hormone level than those bearing only MtT/S cells or a combination of MtT/S cells and fibroblasts. The TtT/GF cell line itself had no tumorigenicity during the experimental period. Therefore, the TtT/GF cell line as a model of FS cells enhanced pituitary endocrine cell tumor formation. Additionally, immunocytochemistry showed that TtT/GF cells positive for glial fibrillary acidic protein (GFAP) or S-100 protein were present in the parenchymatous tissue elements or connective tissue surrounding the tumor nests. In the parenchymatous tissue, the TtT/GF cells exhibited a stellate appearance and surrounded neighboring tumor cells with their long cell processes. These results suggest that TtT/GF cells can serve as a model for pituitary FS cells, and are capable of stimulating pituitary tumor growth either by modifying the microenvironment or producing growth factors.     

Interrelation between membrane transport and the contents of alkali metal cations in HeLa cells

The relation of membrane transport of alkali cations to their external concentrations or to their cellular contents was studied in HeLa cells. Chilling the cells at 0 degrees C reversed cell Na+ and K+ to a mirror image of the normal pattern. Upon rewarming to 37 degrees C the ouabain-sensitive Rb+ uptake became 2-fold faster than the control. A kinetic analysis revealed that the stimulation was due to an increase in the maximal rate of Rb+ uptake, Jmax. The increase in apparent Km was relatively small. The analysis also showed that the ouabain-sensitive cation transport system seemed to have two binding sites for Rb+. The stimulation of Rb+ uptake was related to an increase in cell Na+, and an addition of ouabain abolished such a relation. Net Na+ flux which was in the direction from inside the cells to the medium at hypernormal cell Na+ was iiincreased when cell Na+ ncreased. In contrast, net Na+ flux which was in the opposite direction in the presence of ovabain was reduced and became almost 0 at cell Na+ of 900 nmol/mg of protein. The Na+/Rb+ coupling ratio in the ouabain-sensitive cation transport was apparently less than 1 at nearly physiological cell Na+, but it approached 1.5 when cell Na+ was sufficiently high. The sum of cell K+ plus Rb+ varied inversely with cell Na+, and this relation was unaffected upon treatment with ouabain. When Rb+ uptake declined below 80% of the control, cell K+ plus Rb+ was reduced, however, 40% of the sum of cell cations was still preserved even after complete inhibition of the cation pumps by ouabain treatment of 2 hr. Interrelations of these results are discussed.     

Corticospinal projections from areas 4 and 6 in the raccoon

Summary The corticospinal projections from areas 4 and 6 were investigated in the raccoon using the horseradish peroxidase (HRP) retrograde tracing technique. Multiple injections of lectin bound HRP and HRP were made into either the cervical or lumbar cord in 7 anesthetized raccoons. Retrogradely labeled neurons were observed throughout a wide extent of areas 4 and 6a. The HRP positive cells were most numerous within the dorsal bank of the cruciate sulcus within area 4 and continued around the fundus to occupy the lateral two-thirds of the ventral bank of the cruciate sulcus within area 6a. No labeled cells were observed in the more medially located area 6a. Although the HRP positive cells observed following the lumbar cord injections were situated slightly more medial and caudal to those observed following the cervical cord injections, considerable overlap between the two projections was noted. The corticospinal projections arising from areas 4 and 6a in the raccoon largely correspond in location to the regions functionally defined as the primary motor cortex and the supplementary motor area, respectively.     

Mutation analysis of two Japanese patients with Fanconi-Bickel syndrome

Fanconi-Bickel syndrome (FBS), or glycogen storage disease type XI, is a rare autosomal recessive disorder characterized by hepatorenal glycogen accumulation, Fanconi nephropathy, and impaired utilization of glucose and galactose. Recently, this disease was elucidated to link mutations in the glucose transporter 2 (GLUT2) gene. Only three mutations in three FBS families have been reported. Therefore, it is important to elucidate mutations in the GLUT2 gene in FBS by answering the question of whether the syndrome is a single gene disease. In this report, we describe two patients in two unrelated families clinically diagnosed with FBS. No mutation in the entire protein coding region of the GLUT2 gene was detected in patient 1, which suggested that no mutation existed in the GLUT 2 gene, or that some mutations had affected the expression of the GLUT 2 gene. In patient 2, a novel homozygous nonsense mutation (W420X, Trp at codon 420 to stop codon) was detected. These results support the correlation between GLTU2 gene mutation and FBS syndrome. However, many patients must be analyzed to determine whether other genes are involved in FBS. Received: July 16, 1999 / Accepted: September 3, 1999     

Effects of fluid flow on elution of hydrophilic modifier from dialysis membrane surfaces

When uremic blood flows through dialyzers during hemodialysis, dialysis membrane surfaces are exposed to shear stress and internal filtration, which may affect the surface characteristics of the dialysis membranes. In the present study, we evaluated changes in the characteristics of membrane surfaces caused by shear stress and internal filtration using blood substitutes: water purified by reverse osmosis and 6.7 wt% dextran70 solution. We focused on the levels of a hydrophilic modifier, polyvinylpyrrolidone (PVP), on the membrane surface measured by attenuated total reflectance Fourier transform infrared spectroscopy. Experiments involving 4 h dialysis, 0-144 h shear-stress loading, and 4 h dead-end filtration were performed using polyester-polymer alloy (PEPA) and polysulfone (PS) membranes. After the dialysis experiments with accompanying internal filtration, average PVP retention on the PEPA membrane surface was 93.7% in all areas, whereas that on the PS membrane surface was 98.9% in all areas. After the shear-stress loading experiments, PVP retention on the PEPA membrane surface decreased as shear-stress loading time and the magnitude of shear stress increased. However, with the PS membrane, PVP retention scarcely changed. After the dead-end filtration experiments, PVP retention decreased in all areas for both PEPA and PS membranes, but PVP retention on the PEPA membrane surface was lower than that on the PS membrane surface. PVP on the PEPA membrane surface was eluted by both shear stress and internal filtration, while that on the PS membrane surface was eluted only by internal filtration.     

The effects of tibial rotation on patellar position

The effects of external and internal tibial rotation on patellar motion were investigated using a magnetic 3Space^® tracker system (Polhemus, Colchester, VT 05446, USA). Seven fresh-frozen adult cadaver knees were used in this study. The muscle alignment of each quadriceps muscle was measured to determine the direction of loading forces. Three loading patterns were used to simulate the unresisted knee extension during sitting, standing from squatting and the stance phase of walking, with different weights applied to each quadriceps muscle at each knee flexion angle. The position of the patella, along with patellar shift, tilt and rotation was measured and compared to external or internal tibial rotation and neutral rotation. In the sitting and squatting simulations the patella showed at the terminal extension of the knee more lateral shift and a more lateral tilt with tibial external rotation than in a neutral position (P < 0.05). In walking simulation, the patella showed more external rotation with external rotation of the tibia than with a neutral one, at the 0, 72 and 90% of the stance phase of walking (P < 0.05). These results demonstrate the importance of external tibial rotation as a factor in the development of patellar dislocations or subluxations, especially in athletes.     

New fluorescent probes E3810 and methoxy E3810 for determining distributions of the apical membrane and the acidic compartment of gastric acid secreting cells.

Substituted benzimidazoles such as omeprazole, E3810 and methoxy E3810 were inhibitors of gastric H+, K(+)-ATPase which is rich in the apical membrane of gastric parietal or oxyntic cells at the secreting state. The acid-activated compounds of omeprazole and methoxy E3810, which have methoxy group at the 5-position in the benzimidazole ring, are fluorescent (excitation wavelength = 370 nm; emission wavelength = 560 nm). The fluorescence disappeared when the activated compounds reacted with the ATPase or glutathione. Using this fluorescence property, the distribution of the intracellular acidic canalicular space in isolated single parietal cells was determined. On the other hand, irradiation with ultraviolet light (335 nm) of the acid-activated compound of E3810 which had been reacted with sulfhydryl group of the ATPase or glutathione resulted in a formation of a fluorescent compound (emission = 470 nm). Using this second fluorescence property, we determined the distribution of the apical membrane of the intracellular canaliculus of isolated single mammalian parietal cells and also the location of the apical membrane on the external surface of newt oxyntic cells.     

Conduction pattern of excitation in the amphibian atrium assessed by multiple-site optical recording of action potentials

Spontaneous action potentials were monitored from multiple sites in the bullfrog atrium using a voltage-sensitive merocyanine-rhodanine dye together with a 100-element photodiode matrix array, and we have assessed the spread of the excitation from the pacemaker. Isochrone curves of conduction were obtained by timing the initiation of the action potential-related optical signals: we constructed maps of the spread. Excitatory waves appeared to conduct radially from the pacemaking area over the atrium, and the conduction velocity in the left atrium exceeded that in the right atrium.