[Intra-bile duct growth of hepatocellular carcinoma: value of biliary dilatation on CT]

In order to evaluate the usefulness of CT in demonstrating biliary invasion by hepatocellular carcinoma, 191 surgically proved cases were studied. Among 191 CT scans performed before surgery, six (3%) showed biliary dilatation. Pathological biliary invasion was found in eight cases (4%). Of these eight cases, four cases (50%) showed biliary dilatation on CT. In six cases with biliary dilatation on CT, pathological biliary invasion was revealed in four cases (67%). In two cases, the large (> or = 6cm) encapsulated tumors located in the hepatic hilum dilated the intrahepatic bile duct without intraductal tumor growth. We concluded that biliary dilatation on CT cannot be a sign of biliary invasion by hepatocellular carcinoma.

Rat kidney thromboxane receptor: molecular cloning, signal transduction, and intrarenal expression localization

Thromboxane (TX) plays important roles in control of renal hemodynamics and water and electrolyte metabolism, and is involved in the pathophysiology of many renal diseases. The aim of the present study is to isolate a rat kidney cDNA encoding functional TX receptor, and to reveal its intrarenal expression localization. A clone (rTXR2) was isolated from a rat kidney cDNA library by a homology screening approach. rTXR2 was shown to encode the amino acid sequence containing seven transmembrane spanning domains representing rat (r) TX receptor. The membrane from COS-7 cells transiently transfected with rTXR2 cDNA was shown to be specifically bound by a thromboxane receptor antagonist, SQ29548. Either in Xenopus oocyte expression or in transfected COS-7 cells, rTX receptor was shown to be linked with Ca2+ messenger system. TX receptor-mediated increase in cytosolic Ca2+ was also observed in cultured glomerular mesangial cells. In situ hybridization showed that rTX receptor mRNA was detected in renal glomeruli, smooth muscle cells in renal arterioles, and transitional cell epithelium of renal pelvis. Reverse transcription linked to PCR applied to microdissected nephron segments indicated the presence of rTX receptor mRNA exclusively in the glomerulus. In conclusion, we have cloned a functional rat kidney TX receptor, which is expressed specifically in renal glomerulus, arterial smooth muscle cells, and transitional cell epithelium of renal pelvis. The present study will provide important insights into the etiology and pathophysiology of renal diseases with relation to TX metabolism.

Changes in the mouse exocrine pancreas after pancreatic duct ligation: a qualitative and quantitative histological study

The pancreatic duct from the splenic lobe, the largest lobe of the pancreas in the mouse, was ligated at 6 weeks of age, with histological and cytological changes in the organ examined 1 day to 16 weeks after the ligation. Changes in the volumes of the pancreatic lobe, exocrine tissue, and interstitial tissue as well as relative total numbers of each cellular element in the organ after duct ligation were stereologically obtained using serial sections of the whole pancreas. Cell sizes, degenerated cell and mitotic cell indices, and nuclear densities of the acinar and ductal cells were also obtained. After duct ligation, the volume of the pancreas increased by interstitial edema in the first 2 days but rapidly decreased thereafter due to atrophy of the exocrine tissue, amounting to 10% or less of normal volume by 7 days. The acinar cells showed an accumulation of the zymogen granules, cytoplasmic condensation and a pyknotic figure of the nucleus; they then were thoroughly deleted with appearance of numerous macrophages. This cell death was suggested to be due to apoptosis. On the other hand, the ductal cells remained in the atrophic pancreas and proliferated with mitotic figures to two times the normal frequency at 3 days, and then formed duct-like structures lacking in the acinar cells. After 2 week, the ductal cells slowly decreased in number also due to cell death, but the pancreas became gradually enlarged by intralobular fatty replacement, to reach a volume approximating that of normal 8 weeks after duct ligation. The stereological method serves for the correct evaluation of cell dynamics including the deletion and proliferation of the cells in the whole organ.

Expressions of nerve growth factor and p75 low affinity receptor after transient forebrain ischemia in gerbil hippocampal CA1 neurons

Expressions of nerve growth factor (NGF) and low affinity p75 NGF receptor (p75 NGFR) in gerbil hippocampal neurons after 3.5-min transient forebrain ischemia were studied. Most hippocampal CA1 neurons were lost (neuronal density = 44 +/- 12/mm) at 7 days after recirculation, while no cell death was found in the sham-control neurons (220 +/- 27/mm). NGF immunoreactivity was normally present in the sham-control hippocampal neurons. However, it decreased in hippocampal CA1 neurons, and slightly decreased in the neurons of CA3 and dentate gyrus areas from 3 hr after recirculation. By 7 days, NGF immunoreactivity returned almost completely to the sham-control level in the CA3 and dentate gyrus neurons but decreased markedly in the CA1 neurons. In contrast, p75 NGFR immunoreactivity was scarcely present in the sham-control hippocampal neurons but was induced from 1 hr after recirculation in the CA1 and CA3 neurons and from 3 hr in the dentate gyrus. At 7 days, p75 NGFR immunoreactivity was expressed greatly in the surviving CA1 neurons and the reactive astrocytes but was not seen in the other hippocampal neurons. The markedly decreased NGF and greatly induced p75 NGFR immunoreactivity found in the CA1 neurons after transient forebrain ischemia suggests that NGF and p75 NGFR may be involved in the mechanism of delayed neuronal death.

Role of calcium in insulin-stimulated NaC1 transport in medullary thick ascending limb

It has been reported that insulin stimulates directly NaCl transport in the rabbit medullary thick ascending limb (MTAL) [O. Ito, Y. Kondo, N. Takahashi, K. Kudo, Y. Imai, K. Omata, and K. Abe. Am. J. Physiol. 267 (Renal Fluid Electrolyte Physiol. 36): F265-F270, 1994]. In the present investigation, we evaluated the role of Ca2+ in insulin-stimulated NaCl transport in rabbit MTAL by in vitro microperfusion methods. In control experiments, insulin increases transepithelial voltage (Vte) and net lumen-to-bath Cl-flux (JCl). The effects of insulin on Vte and JCl in a Ca2+ -free solution containing ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N' -tetraacetic acid did not differ from those in a Ca2+ -containing control solution. Direct measurements of cytosolic free Ca2+ ([Ca2+]i) with fura 2 fluorescence showed that insulin caused no detectable change in [Ca2+]i in MTAL cells. Chelation of intracellular Ca2+ with the acetoxymethyl ester of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid inhibited the actions of insulin in Vte and JCl without affecting basal values. We examined further whether calmodulin is also involved in insulin-stimulated NaCl transport in MTAL using two dissimilar inhibitors of calmodulin, trifluoperazine (TFP) and N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7). TFP and W-7 inhibited the action of insulin in a dose-dependent manner, with maximal inhibition of both agents of > 90%. The half-maximal inhibition by TFP and W-7 was approximately 50 and 100 microM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

[Electrolyte metabolism in renal tubules]

Obese, diabetic and hypertensive populations have an increased prevalence of hyperinsulinemia and insulin resistance with respect to glucose metabolism. Insulin is thought to contribute to hypertension by sodium retention in the kidney. Here we describe the direct effect of insulin on renal tubular transport. The ascending thin limb of Henle's loop (ATL) plays an important role in concentrating urine. However, it is still controversial whether Na+ reabsorption in this nephron segment is an active process or a passive one. Moreover hormonal regulation of Cl- transport in the ATL is completely unknown. Therefore we also describe the mechanism of Na+ transport and hormonal regulation of Cl- transport in the ATL.

[Quick-freeze, deep-etch study of monkey lamina cribrosa]

Quick-freeze, deep-etch method was used to study the ultrastructure of normal monkey optic nerve lamina cribrosa. Glial cell somata were located beside collagen fibril bundles in the lamina cribrosa. Glial intermediate filaments, which were the main cytoskeletal proteins of 10-12 nm in diameter, were loosely packed in the somata and were tightly stacked in the processes. The glial plasma membrane directly abutted onto the myelin sheath of the optic nerve axon. The main component of the extracellular matrix (ECM) in the lamina cribrosa was interstitial collagen fibers of 30-60 nm in diameter, which were bridged by processes 5 nm in diameter and 20-30 nm in length and by 5 nm wide mesh-like structures. Small vessels running in the laminar beams were totally surrounded by basement membranes, laminar ECM, and glial cell components and thus were separated from optic nerve axons. The basement membrane which surrounded the laminar ECM was a fine fibrillar structure of 5 nm in diameter and also had numerous fibrils anchoring it to plasma membranes of vascular pericytes and glial cells.

Analysis of spinocerebellar ataxia type 1 (SCA1)-related CAG trinucleotide expansion in Japan

Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disorder caused by expansion of a CAG trinucleotide repeat. We analyzed CAG repeat expansion in 25 families in the northeast of Japan with hereditary ataxia of Menzel type. Twenty of 38 patients in 12 families had expanded allele for SCA1. The number of CAG repeats correlated with the age at onset. Although the relationship between anticipation and the number of CAG repeats in successive generations was not ascertainable, there was a tendency to paternal bias for the accelerated age at onset. Study of the number of CAG repeats in various tissues showed no differences in the repeat length in lymphocytes, muscle, or brain; sperm, however, showed an obvious expansion. This may be a clue to a possible mechanism for the molecular basis of paternal anticipation of the disease. The SCA1 gene was transcribed from both wild and mutated alleles in muscles of affected individuals, but the repeat length was the same for both the muscle cDNA and the lymphocyte genomic DNA. These results suggest that, in the area of Japan where SCA1 is prevalent, 48% of families with spinocerebellar degeneration have SCA1 mutation.

Ischemic delayed neuronal death. A mitochondrial hypothesis

BACKGROUND

A brief period of global brain ischemia causes cell death in hippocampal CA1 pyramidal neurons days after reperfusion in rodents and humans. Other neurons are much less vulnerable. This phenomenon is commonly referred to as delayed neuronal death, but the cause has not been fully understood although many mechanisms have been proposed.

SUMMARY OF REVIEW

Hippocampal CA1 neuronal death usually occurs 3 to 4 days after an initial ischemic insult. Such a delay is essential for the mechanism of this type of cell death. Previous hypotheses have not well explained the reason for the delay and the exact mechanism of the cell death, but a disturbance of mitochondrial gene expression could be a possibility. Reductions of mitochondrial RNA level and the activity of a mitochondrial protein, encoded partly by mitochondrial DNA, occurred exclusively in CA1 neurons at the early stage of reperfusion and were aggravated over time. In contrast, the activity of a nuclear DNA-encoded mitochondrial enzyme and the level of mitochondrial DNA remained intact in CA1 cells until death. Immunohistochemical staining for cytoplasmic dynein and kinesin, which are involved in the shuttle movement of mitochondria between cell body and the periphery, also showed early and progressive decreases after ischemia, and the decreases were found exclusively in the vulnerable CA1 subfield.

CONCLUSIONS

A disturbance of mitochondrial DNA expression may be caused by dysfunction of the mitochondrial shuttle system and could cause progressive failure of energy production of CA1 neurons that eventually results in cell death. Thus, the mitochondrial hypothesis could provide a new and exciting potential for elucidating the mechanism of the delayed neuronal death of hippocampal CA1 neurons.

Resetting of parathyroid hormone secretion after vitamin D3 treatment in hypoparathyroidism and after parathyroid adenectomy in primary hyperparathyroidism

The relationship between parathyroid hormone (PTH) secretion and extracellular calcium (Ca) level is reciprocal causality. The equilibrium operating point determines basal PTH secretion rate and basal extracellular Ca level. We studied how this equilibrium was achieved in the subjects with decreased PTH secretion or decreased parathyroid glands number. Basal/maximum ratio of serum PTH, which reflects the basal secretory state of parathyroid glands, was increased in 9 hypoparathyroid patients treated with vitamin D3 (VD3) [7 patients with idiopathic hypoparathyroidism] and in seven of nine parathyroid adenectomized patients. There was a negative correlation between the ratio and basal serum Ca level in the patients with IHP after VD3 treatment (r = 0.7167, P < 0.05) and in the patients after parathyroid adenectomy (r = 0.7760, P < 0.05). The regression curves in these two groups coincided regardless of the difference in maximum PTH secretion rate, which suggested that the basal secretory state of parathyroid glands was determined by extracellular Ca level in a similar manner in these subjects. There was a sigmoidal relationship between basal/maximum ratio of serum PTH and basal serum Ca level, when the data were collected from 15 hypoparathyroid patients before or after VD3 treatment, 9 parathyroid adenectomized patients, and 10 normal subjects (r = 0.9057, P < 0.001). This sigmoidal curve is thought to represent the fundamental relationship between the basal secretory state of parathyroid glands and extracellular Ca level.

Three-dimensional arrangement of collagen and elastin fibers in the human urinary bladder: a scanning electron microscopic study

To clarify the arrangements of collagen and elastin fibers of the urinary bladder, we examined 9 human (male, aged 42 to 72) urinary bladders by scanning electron microscopy with chemical digestion methods. The mucosal layer was divided into 3 portions according to the collagen arrangement: the superficial portion interwoven densely by collagen fibrils, the middle portion layered by flat bundles of collagen fibrils and the deep portion made of a loose network of twisted collagen bundles. In the muscular layer, the smooth muscle fascicles were firmly covered with collagen sheets, while each muscle cell in a fascicle was accommodated by a thin sheath of collagen fibrils. The serosal layer consists of wavy collagen bundles piled up in a sheet, which was intercalated by clusters of adipose cells. Elastic fibers were, on the other hand, sparse throughout the bladder wall, except for denser networks around the blood vessels and muscle fascicles and beneath the peritoneal mesothelium. The arrangements of these components were discussed in relation to the mechanical function and compliance of the urinary bladder.

Two cases of pheochromocytoma diagnosed histopathologically as mixed neuroendocrine-neural tumor

We treated two rare cases of pheochromocytoma which were histopathologically diagnosed as mixed neuroendocrine-neural tumor (MNNT): a 35-year-old male patient associated with ganglioneuroblastoma and cutaneous neurofibromatosis and a 42-year-old male patient with ganglioneuroma. Both patients showed typical clinical manifestations of pheochromocytoma without any familial traits. Although each of the diseases has its own entity and clinical features, these tumors are all derived from the neural crest tissues. The tumorigenesis of MNNT is still unknown. Here, a brief review of the recent literature on this subject is discussed.

Totally implantable ventricular assist system using a vibrating flow pump

A totally implantable ventricular assist system (VAS), including a drive system and a percutaneous electric energy transmission system, was developed and evaluated in acute animal experiments using adult goats. This newly designed VAS mainly consists of a vibrating tube, coils, magnets, and a jelly-fish valve as the outlet valve. For energy transmission, a new implantable transmitter with a plain weave structure was proposed as a noncontacting transform by using the spinal amorphous magnetic fibers. The fluid mechanical and hemodynamic properties and the efficiency of the energy transmission system were evaluated in acute animal experiments using healthy adult goats. This vibrating electromagnetic artificial heart (AH) could generate more than 10 L/min as output volume, with 10 Hz vibration using 20 volts as supplied voltage. The total efficiency of the percutaneous energy transmission system was 76%, and temperature increases were within the acceptable range, suggesting the usefulness of our newly developed implantable VAS.

Effects of V1- and V2-vasopressin (AVP) antagonists on the pressor, AVP and atrial natriuretic peptide responses to a hypertonic saline infusion in conscious anephric rats

To examine the role of vasopressin (AVP) receptors in the regulation of the hemodynamics and release of atrial natriuretic peptide (ANP), and the participation of renal nerve inputs in the osmotic AVP release, hypertonic saline (HS) was infused into conscious, bilaterally nephrectomized rats with non-peptide, selective antagonists for the V1-receptor or V2-receptor of AVP. In the control group, HS alone increased mean arterial pressure, plasma ANP and AVP, plasma volume and plasma osmolality, and decreased the heart rate. In the V1-receptor antagonist group, an increase in the mean arterial pressure and a decrease in heart rate were completely abolished and an increase in plasma ANP was attenuated. In the V2-receptor antagonist group, increases in mean arterial pressure and plasma ANP and a decrease in heart rate were attenuated. However, the ratio of the changes in heart rate to the changes in mean arterial pressure in the V2-receptor antagonist group is significantly higher than that in the control group. In both experimental groups, increases in plasma AVP, plasma volume and plasma osmolality were not different from those in the control group. These results suggest that a HS-induced increase in mean arterial pressure is mediated by the pressor effect of AVP, mainly through V1-receptors, and that the depressor effect of AVP through V2-receptors may not influence tonically HS-induced hypertension. Moreover, HS-induced increase in plasma ANP is mediated mainly by increases in plasma volume and blood pressure, but may not be affected by a direct action of AVP to the heart. Renal afferent nerve inputs may not have effects on the regulation of osmotic AVP release.

Rapid and semiquantitative analysis of HSP72 and HSC73 heat shock mRNAs by mimic RT-PCR

The amounts of mRNAs for 72 kDa (HSP72) and 73 kDa (HSC73) heat shock proteins were measured semiquantitatively with competitive polymerase chain reaction (PCR) techniques after reverse transcription (RT) using a heterologous DNA fragment (PCR mimic) as an internal standard. The changes of signal intensities of PCR products were well correlated with the amount of mRNA in rat brain measured as optical densities of Northern blot. Thus, an analysis with mimic RT-PCR technique provides a rapid, semiquantitative, and safe method to detect changes of HSP72 and HSC73 mRNAs after brain ischemia.

Amygdala N-methyl-D-aspartate receptors participate in the induction of long-term potentiation in the dentate gyrus in vivo

We investigated the effects of injection of N-methyl-D-aspartate (NMDA) receptor antagonists, 2-amino-5-phosphonovalerate (APV) and 7-chlorokynurenate (7-Cl-Kyn), into the basolateral amygdala (BLA) on long-term potentiation (LTP) in the medial perforant path-dentate gyrus granule cell synapses of anesthetized rats. Injection of APV or 7-Cl-Kyn into the ipsilateral BLA did not affect the baseline synaptic responses, but significantly attenuated the dentate gyrus LTP induced by tetanic stimulation. Injection of APV into the contralateral BLA did not affect the induction of LTP. When APV was injected after tetanic stimulation, it did not affect the maintenance phase of LTP. These results suggest that NMDA receptors in the ipsilateral BLA partly participate in the induction of LTP in the dentate gyrus in vivo.

CT scanning of bronchioloalveolar carcinoma: specific appearances

We reviewed CT scans in 38 cases with pathologically proved bronchioloalveolar carcinoma. CT revealed three CT patterns: solitary, pneumonic and diffuse forms. The solitary pattern (22 patients) had a high percentage of air bronchograms (95%), pleural indentation (77%) and spiculation (68%). The pneumonia-like pattern (16 lesions in 10 patients) had air bronchograms in all cases (100%), low attenuation (88%) and protrusion of interlobar fissures (63%). The diffuse form (six patients) had 2 or 3 mm diffuse small nodules scattered throughout the entire lung. CT of bronchioloalveolar carcinoma revealed many findings and was useful in recognizing the tumor distribution and extent. We conclude that CT is helpful for the diagnosis and evaluation of bronchioloalveolar carcinoma.

Fluid and protein secretion by the submandibular glands of weanling rats in response to cholinergic and peptidergic agonists at various doses

Fluid and protein secretion by the submandibular glands of 25-day-old rats were examined and compared in response to three cholinergic and four peptidergic sialogogues at various doses. All cholinergic and peptidergic agonists used were potent sialogogues for the submandibular glands of the weanling rats over the wide range of doses used. The cholinergic agonists, bethanechol and methacholine and the peptidergic agonists, substance P, substance PTyr8 and eledoisin-related peptide used intravenously, acted similarly to each other on the submandibular glands of the rats, late in the natural weaning period, but carbachol and physalaemin had slightly different effects. Of the peptidergic agonists, physalaemin was the most potent sialogogue among four tachykinins tested at the low dose. The types of protein secreted by the submandibular glands of the weanling rats in response to all sialogogues used here were typical of the beta-type. These results indicate that all agonists used could mainly stimulate the acinar cells of the submandibular glands of the weanling rats which have already fully developed functionally at this time.

Cytosolic Ca2+ dynamics in hamster ascending thin limb of Henle's loop

Intracellular calcium plays an important role in the regulation of Cl- reabsorption in the ascending thin limb of Henle's loop (ATL). To elucidate the cytosolic Ca2+ dynamics in the ATL, intracellular Ca2+ concentration activity ([Ca2+]i) was measured in the in vitro microperfused hamster ATL using fura 2. Basal [Ca2+]i was 89.1 +/- 7.3 nM (n = 9 tubules). Removal of Ca2+ from the peritubular solution decreased [Ca2+]i from 89.1 +/- 7.3 to 64.1 +/- 7.1 nM in 2 min (n = 9, P < 0.05), whereas [Ca2+]i did not change after removal of Ca2+ from the luminal solution. Addition of 1 mM NaCN to the bath increased [Ca2+]i. This effect was completely abolished by the elimination of ambient Ca2+. Trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) in the bath reversibly increased [Ca2+]i, whereas addition of 1 mM ouabain to the bath decreased [Ca2+]i. Rates of changes in [Ca2+]i after removal and replacement of basolateral Ca2+ were not affected by removal of Na+, K+, or Cl- from the bath, whereas nicardipine decreased these parameters. Increasing bath K+ from 5 to 100 mM decreased [Ca2+]i from 69.3 +/- 5.8 to 50.8 +/- 5.0 nM in 1 min (n = 6, P < 0.05). Subsequent reduction of K+ from 100 to 5 mM increased [Ca2+]i to 174.0 +/- 30.8 nM in 1 min, followed by a gradual decrease in [Ca2+]i to a steady-state level of 74.2 +/- 8.0 nM in 2 min. Changes in basolateral K+ concentration did not affect [Ca2+]i in the absence of ambient Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)