Effects of nerve growth factor and glucocorticoid on cultured human pheochromocytoma cells

Primary cell cultures of two human pheochromocytomas (PC) that were associated with high serum levels of adrenaline and noradrenaline were developed to study the effects of nerve growth factor (NGF) and dexamethasone on the morphology and function of PC cells in vitro. By phase-contrast microscopy, cultured cells were small and hyperchromatic on the first day of culture; neurite-like processes that extended to other cells developed several days later and were maintained for more than 3 months. NGF (100ng/ml), dexamethasone (10^–5M), or NGF + dexamethasone were added to the culture media 2 weeks after the cultured cells had stabilized. Catecholamine concentrations in the medium were maintained at higher levels after addition of NGF, dexamethasone, or NGF + dexamethasone as compared to control cells. In the presence of NGF, extension of neurite-like processes was clearly accelerated, while high levels of dexamethasone inhibited growth of processes. These in vitro studies showed that the addition of NGF or the removal of dexamethasone induces differentiation of adrenal neurons present in pheochromocytomas, suggesting that adrenocortical steroid hormones influence the morphological control of adrenal medullary cells.     

Positive regulator for the expression of Mba protein of the virulence plasmid, pKDSC50, of Salmonella choleraesuis.

A positive regulator was identified within a 2.3 kb fragment of the 6.4 kb mouse bacteremia region (mba region) of the virulence pKDSC50 plasmid of Salmonella choleraesuis. Sodium dodecyl sulphate polyacrylamide gel electrophoresis showed that Escherichia coli K-12 carrying the recombinant plasmids of the 2.3 kb fragment produced Mba1 protein with a molecular mass of 32 kDa. The recombinant plasmids carrying a 4.1 kb fragment, the other part of 6.4 kb region, produced Mba2 (32 kDa), Mba3 (70 kDa) and Mba4 (29 kDa) proteins. All three proteins were expressed by using the lacZ promoter under isopropyl thiogalactoside induction. In contrast to this, Mba3 protein was overexpressed independently of the lacZ promoter when the 2.3 kb fragment coexisted either in cis or trans. These results suggest that Mba1 is a trans-acting positive regulator for the expression of the Mba3 protein of mba region of pKDSC50.     

Control of feeding rhythm in the terrestrial slug Incilaria bilineata.

A modulatory neuron of feeding rhythm was newly identified in the buccal ganglia of the isolated central nervous system (CNS) of the terrestrial slug Incilaria bilineata. This neuron was termed the "feeding rhythm modulator" (FRM). Its morphological and electrical properties were compared with those of the MGC (metacerebral giant cell, a cerebral modulatory neuron of feeding rhythm). There was no direct connection between FRM and MGC. In order to investigate the control mechanism of the buccal central pattern generator, feeding rhythm was observed by varying the activities of MGC and FRM simultaneously. At a lower level of activity of MGC, feeding rhythm was not only sensitive to the activity of MGC but also to that of FRM. As the level of activity of MGC increased, feeding rhythm was exclusively controlled by the activity of MGC, and became unaffected by the activity of FRM. This indicates that cerebral neurons such as MGC primarily control feeding rhythm and modulate the contribution of FRM in a hierarchical manner.     

Pathological Aspects of Radiofrequency Catheter Ablation of the Canine Atrioventricular Node and Bundle of His

Radiofrequency catheter ablation of the atrioventricular (AV) node or bundle of His was performed in 12 adult mongrel dogs. The aim was to create chronic incomplete AV block (first- and second-degree AV block) and to examine the histopathology of the ablated lesions. However, the late electrophysiological results (2 4 weeks follow up) were various: normal in 2 dogs, mild PR prolongation (< 50%) in 2 dogs, first-degree AV block (PR prolongation a 50%) in 2 dogs, second degree AV block in 2 dogs, complete AV block in 4 dogs. The maximally ablated area (%) of the atrioventricular conduction system in serial histologic sections from dogs with these conditions was 69%, 75%, 89.5%, 95% and 99.5%, respectively. The number of intact conduction cells at the maximally ablated site varied from 6 to 30 in the four cases of incomplete AV block. The mean ablated volume (%) of either the AV node or penetrating His bundle correlated roughly with the degree of AV block. The ablated lesions were well demarcated and almost replaced by dense fibrous tissue at 4 weeks. Interruption (3 dogs) or thinning (1 dog) of the endocardial elastic lamellae was detected, in association with endocardial thickening (mean 913 μm). Endocardial thrombi were found in 3 dogs (2 fresh, 1 organized). We conclude that radiofrequency catheter ablation does not cause severe complicated lesions. Several possible conditions for creating chronic incomplete AV block are discussed. Acta Pathol Jpn 41: 487–498, 1991.     

Development of renal potassium excretion capacity in the neonatal rat

We investigated the capacity of newborn rats to excrete an acute potassium load to understand the development of a renal potassium excretion system. Three groups of the rats (7-14 d) were used to collect urine periodically over 6 h after oral infusion of potassium: control (no potassium loading) and low- and high-potassium-loaded rats. In the low-potassium-loaded group, infused with about 0.6 microEq of potassium chloride/g body wt., the rate of renal potassium excretion increased from 0.08 plus minus 0.02 (7 d) to 0.13 plus minus 0.02 (10 d) and 0.21 plus minus 0.03 (14 d) microEq/h/g body wt. The high-potassium-loaded rats (1.5-2.8 microEq/g body wt. potassium load) excreted potassium at a higher rate of 0.18 +/- 0.05 (7 d), 0.30 +/- 0.02 (10 d), and 0.45 +/- 0.10 (14 d) microEq/h/g body wt. They excreted 77% (7 d), 76% (10 d), and 95% (14 d) of the potassium load. These values were much larger than the rate of 0.026 microEq/h/g body wt. of the control rats and of 0.08 microEq/h/g body wt., a mean potassium excretion rate during development from 7 to 14 d calculated from the data in the previous study (Kanno T et al.: J. Pediatr. Gastr. Nutr. 24: 242-252, 1997). In the same period, serum potassium concentration in the newborn rats decreased significantly (p < 0.01) from 7.2 +/- 0.1 (7 d) to 6.7 +/- 0.1 mEq/l (14 d). All these results suggest that a renal potassium excretion system in the rat develops at least in the second week of life, and its capacity is high enough to excrete the daily potassium intake.     

Tissue distribution of the Pk antigen as determined by a monoclonal antibody

Using an anti-Pk monoclonal antibody (mAb) designated CPK-1, the expression of the Pk antigen was assessed on normal human tissue from non-Pk individuals. Although the Pk antigen was detected on fibroblasts and blood vessels as previously reported, it was also found on smooth muscle cells of the digestive tract and the urogenital system. Pk was also found on glandular cells of the stomach, oesophagus and prostate. Additionally, CPK-1 reacted weakly with oesophagus squamous cells, and a small number of glomeruli and tubules in the kidney. The mechanism of expression of the Pk determinant in non-Pk individuals is discussed.     

The effects of prostaglandin E1 on the pepsin activities in gastric mucosa and juice.

Prostaglandin E1 elevated pepsin activity in gastric mucosa but lowered pepsin activity in the gastric juice of rats treated by pylorus ligation and intragastric administration of hydrochloric acid. In these animals zymogen granules with low electron density were numerous in the gastric chief cells following prostaglandin E1 treatment. The prostaglandin E1-induced increase in mucosal pepsin activity was slightly inhibited by actinomycin D and there was no apparent increase in 3H-thymidine incorporation into gastric mucosa following treatment with prostaglandin E1. It is suggested that prostaglandin E1 causes an elevation of pepsin activity in the gastric mucosa by stimulating pepsin synthesis and perhaps also by facilitating pepsin release from zymogen granules. However, it also appears to inhibit pepsin release from the mucosa into the gastric cavity judging by the decrease of pepsin activity in gastric juice. The reduced pepsin activity in gastric juice may account, in part, for the reported anti-ulcerative action of prostaglandin.     

Control of feeding rhythm in the terrestrial slug Incilaria bilineata

A modulatory neuron of feeding rhythm was newly identified in the buccal ganglia of the isolated central nervous system (CNS) of the terrestrial slug Incilaria bilineata. This neuron was termed the “feeding rhythm modulator” (FRM). Its morphological and electrical properties were compared with those of the MGC (metacerebral giant cell, a cerebral modulatory neuron of feeding rhythm). There was no direct connection between FRM and MGC. In order to investigate the control mechanism of the buccal central pattern generator, feeding rhythm was observed by varying the activities of MGC and FRM simultaneously. At a lower level of activity of MGC, feeding rhythm was not only sensitive to the activity of MGC but also to that of FRM. As the level of activity of MGC increased, feeding rhythm was exclusively controlled by the activity of MGC, and became unaffected by the activity of FRM. This indicates that cerebral neurons such as MGC primarily control feeding rhythm and modulate the contribution of FRM in a hierarchical manner.     

Brighton epistaxis balloon: application for cranio-facial injury

Head injury patients often complicate facial and/or multiple injuries other than cranio-cerebral insults and perplex the emergency staffs. The authors used Brighton epistaxis balloon for such patients with massive nasal bleeding and reported the utility of the balloon not only in such state of emergency but also for a few days to control the hemorrhage mostly caused by craniobasal fractures or rupture of the adjacent vessels. One hundred and twenty-nine patients were transported and hospitalized in Department of Emergency Medicine, University of Tokyo Hospital, Tokyo, Japan during the period from October, 1981 to January, 1983. Nasal bleeding was noted in 29 cases of them and the balloon was used in 10 cases, who were from 19 to 76 years of age, all males and suffered from basal fractures or craniofacial injuries. Six cases of them were also accompanied with fractures in the extremities or pelvis, hemopneumothorax and/or intra-abdominal bleeding and could not but put on "Military anti-shock trousers" for the management of hypovolemic shock, hence the nasal bleeding should be managed immediately in the emergency room. In these situations the balloon was inserted into both nasal cavities in all the patients, to control successfully the nasal hemorrhages one of which contaminated cerebrospinal fluid and three of which were sure to be pulsatile due to arterial injury. The Brighton epistaxis balloon is to be removed within twelve or twenty-four hours, but in the authors' cases the mean duration for the hemostasis was 58.9 hours for 6 survivors and 49.6 hours for all 10 cases.(ABSTRACT TRUNCATED AT 250 WORDS)