Comparison of the size of neuronal and non-neuronal histamine pools in the brain of different rat strains

Summary The size of the neuronal and non-neuronal histamine pools in the brain of three different strains of rats was measured by assuming that the -fluoromethylhistidine-induced maximal decrement of histamine represents the size of the neuronal pool. Although the total histamine levels in the brain showed a considerable interstrain variation, no significant interstrain difference was observed in the neuronal histamine level. These results suggest that the size of the neuronal histamine pool in the brain is relatively stable, whereas the size of the non-neuronal histamine pool is variable.     

Enhancement of blood-brain barrier permeability to sodium fluorescein by stimulation of µ opioid receptors in mice

Summary The effects of opioids on the permeability of the blood-brain barrier (BBB) were examined in mice with sodium fluorescein as an indicator of the permeability. The brain was perfused with saline 30 min after injection of sodium fluorescein (40 mg/kg, i. v.) and examined by fluorometry. Morphine hydrochloride (0.3–10 mg/kg, s. c.) markedly increased the brain level of sodium fluorescein dose-dependently without influencing the plasma level, when administered 20 min before sodium fluorescein injection. Intracerebroventricularly (i. c. v.) injected morphine hydrochloride (0.5 and 1.0 Erg) increased the brain sodium fluorescein level. Buprenorphine (0.1 and 0.5 mg/kg, s. c.) was also effective. However, pentazocine, ethylketazocine, U-50488H and SKF-10047 had no significant influence. The i.c.v. administration of [D-Ala², McPhe⁴, Gly(ol)⁵]enkephalin (0.1 g) and [D-Ala², D-Leu⁵]enkephalin (0.5 g) but not of [D-Thr², Leu⁵]enkephalin-Thr increased the brain level of sodium fluorescein significantly. A small dose of naloxone (i. p.) significantly inhibited the effects of morphine, buprenorphine, [D-Ala², McPhe⁴, Gly(ol)⁵]enkephalin and [D-Ala³, D-Leu⁵]enkephalin. ICI-174864 co-administered i. c. v. with [D-Ala², D-Leu⁵]enkephalin was ineffective in antagonizing the effect of the latter. These findings suggest that the stimulation of µ opioid receptors results in an increase in BBB permeability to sodium fluorescein. Send offprint requests to K. Saeki     

Transient induction of single GST-P positive hepatocytes by DEN

The single cells positive for placental glutathione S-transferase(GST-P), detectable in livers of rats soon after treatment withhepatocarcinogens, are possible ‘initiated cells’,the hypothesis tested in the present series of experiments.No low dose threshold was observed in male Sprague-Dawley ratsat different single doses of diethylnitrosamine (DEM) althougha plateau was reached between 160 and 200 mg/kg body weight.At the latter single dose 12 400 positive cells/cm³ were observedimmunohistochemically in rat livers after one week, the numbersthen decreasing to week 8 and thereafter rising again. In thenumbers then decreasing to week 8 and thereafter rising again.In the early stages single cells predominated but with timea gradual increase in mini-foci and larger lesions became evident.Application of selection pressure (feeding of diet containing0.02% 2-AAF plus partial hepatectomy) to rats 2–24 weeksafter single DEN-treatment resulted in the formation of largefoci positive for GST-P, especially in the early stages, thegrowth response being less pronounced with time. The numberof foci, on the other hand. was correlated with the number offoci, on the other hand, was correlated with the number ofsingle cells/mini-foci detected inhepatectomy tissue of thesame individuals. These results suggest that the early GST-Ppositive populations could be the precursor for preneoplasticfoci and nodules.     

Single nucleotide polymorphisms in the protamine-1 and -2 genes of fertile and infertile human male populations

Although various genetic factors have been implicated in human male infertility, the causative genes for the different types of idiopathic male infertility have not been elucidated. Protamines, which are the major DNA-binding proteins in the sperm nucleus, package the DNA into the sperm head. Analysis of the human protamine-1 (PRM1) and -2 (PRM2) gene sequences in 226 sterile male patients and in 270 proven-fertile male volunteers revealed four single nucleotide polymorphisms (SNPs) in the PRM1 coding region, which did not cause any amino acid substitutions, and one SNP in the PRM2 gene, which produced translation termination. We also observed one SNP in the 3' non-coding region of the PRM1 gene, and two SNPs within the intron of the PRM2 gene. The prevalence of these SNPs was similar in both infertile patients and in proven-fertile volunteers, except that the c248t alteration in the PRM2 gene induced a nonsense codon under conditions of heterozygosity in one infertile patient. Although the PRM1 and PRM2 genes are highly conserved, the single SNP in the PRM2 gene that induces translation termination may result in male infertility due to haploinsufficiency of PRM2.     

Rhythmic motor activity in thin transverse slice preparations of the fetal rat spinal cord

Networks generating locomotor-like rhythmic motor activity are formed during the last week of the fetal period in the rat spinal cord. We investigated the coordinated rhythmic motor activity induced in transverse slice preparations of the lumbar spinal cord taken from fetal rats as early as embryonic day (E) 16.5. In slices as thin as 100 microm, bath-application of 5-hydroxytryptamine (5-HT) induced rhythmic [Ca(2+)](i) elevations in motoneurons labeled with Calcium Green-1 dextran. The rhythmic [Ca(2+)](i) elevations were similar in frequency to that in the intact lumbar spinal cord, although there was no temporal correlation between the activity in the left and right sides of 100-microm slices. Such rhythmic [Ca(2+)](i) elevations were observed in the slices taken from all lumbar segments. Moreover, the rhythmic activity was abolished by simultaneous blockade of glutamate, glycine, and GABA(A) receptors, indicating that synaptic transmission mediated by these receptors is important for the generation of the rhythm in these slices. Synchronous rhythmic activity between the left-right sides was found in slices thicker than 200 microm taken from any segmental level of the lumbar spinal cord. In these preparations, commissural neurons were activated synchronously with ipsilateral motoneurons. These results indicate that the neuronal networks sufficient to generate coordinated rhythmic activity are contained in one-half of a single lumbar segment at E16.5. Such spinal cord slices are a promising experimental model to investigate the neuronal mechanisms and the development of rhythm generation in the spinal cord.     

Bone-implant interface mechanics of in vivo bio-inert ceramics

We have previously demonstrated that there was no significant difference between the affinity of bone to bio-inert ceramics and stainless steel in a histological study. In this study, the bone-implant interface shear strength of alumina ceramics (AI₂O₃), zirconia ceramics (ZrO₂), stainless steel (SUS316L) and sintered hydroxyapatite (HA) were compared in 19 dogs using a transcortical push-out model of the femur 4 and 12 wk after implantation. The interface shear strength of HA was significantly greater than that of alumina ceramics, zirconia ceramics and stainless steel (P < 0.001). There was no significant difference between bio-inert ceramics and stainless steel.     

Small cell carcinoma of the extrahepatic bile duct: case report and immunohistochemical analysis

A small cell carcinoma of the extrahepatic bile duct in a 75-year-old Japanese man is reported. The patient suffered from obstructive jaundice, and percutaneous transhepatic cholangiography-drainage (PTCD) revealed a massive lesion in the lower common bile duct. Because it was diagnosed as a malignant tumor, pancreaticoduodenectomy was performed. A nodular infiltrating tumor measuring 4.5 x 3.0 x 2.0 cm was located in the intrapancreatic portion of the extrahepatic bile duct. Histologically, the tumor was composed of a dense proliferation of small atypical cells with a little region of high-grade dysplasia in the adjacent epithelium of the common bile duct. Tumor cells were immunoreactive to neuroendocrine markers such as chromogranin A, synaptophysin, CD56, and Leu7. Although carcinoma cells invaded into pancreas and duodenum, there were no histological findings that indicated the carcinoma arose from the mucosa of either the pancreatic duct or duodenum. These results indicated that the tumor was a small cell carcinoma derived from the epithelium of the extrahepatic bile duct; a rare neoplasm with only a few cases reported. A few neuroendocrine cells were recognized in the adjacent epithelium of the extrahepatic bile duct, suggesting that the tumor cells might be derived from them. Using immunohistochemical examination, no p53 abnormality was found. Tumor cells showed positive nuclear staining for p16, while negative for cyclin D1, suggesting that functional retinoblastoma protein (pRB) might be lost in the p16/pRB pathway, as in small cell lung cancer.     

High incidence of pre-excitation syndrome in Japanese families with Leber's hereditary optic neuropathy

Cardiac conduction abnormalities have been reported in families with Leber's hereditary optic neuropathy (LHON). The pre-excitation syndrome, Wolff-Parkinson-White syndrome or Lown-Ganong-Levine syndrome, is reportedly common in Finns with LHON, being seen in 14 (9%) of the 163 individuals with mitochondrial DNA (mtDNA) mutations. While this syndrome is thought to be rare in other ethnic groups with LHON, the present study of 35 Japanese LHON families confirmed that it is also relatively common among Japanese families, being seen in 5 (8%) of the 63 individuals with mtDNA mutations. It remains to be determined whether the high incidence of the pre-excitation syndrome in Finnish and Japanese LHON families is due to a particular genetic composition of ethnic groups such as in Finland and in Japan, or only to a reporting bias.