Calcium-dependent immediate feedback control of inositol 1,4,5-triphosphate-induced Ca2+ release. The temporal and spatial distribution of increases in intracellular Ca2+ concentration is an important factor in cellular signal transduction. Inositol 1,4,5-trisphosphate (InsP3) plays a key part in agonist-induced Ca2+ release, which can take place abruptly and in a confined space by a mechanism that is not fully understood. Here we analyse the kinetics of InsP3-induced Ca2+ release following flash photolysis of caged InsP3 or caged Ca2+, and demonstrate that Ca(2+)-dependent immediate feedback control is an important determinant of the time course of Ca2+ release. The positive feedback mechanism is also important for the 'loading dependence' of InsP3-induced Ca2+ release. Furthermore, our results support the operation of positive cooperativity in channel opening and feedback control augments the steep InsP3 concentration-Ca2+ release relation. These inherent properties of InsP3-induced Ca2+ release are expected to give rise to temporally abrupt and/or spatially confined Ca2+ release within the cell.


Function of a truncated dihydropyridine receptor as both voltage sensor and calcium channel. The skeletal muscle dihydropyridine (DHP) receptor serves dual functions, as a voltage sensor for excitation-contraction coupling and as an L-type calcium channel. Biochemical analysis indicates the presence of two forms of the DHP receptor polypeptide in skeletal muscle, a full-length translation product present as a minor species and a much more abundant form that has a truncated carboxy-terminus. On the basis of these and other observations, it has been proposed that, in skeletal muscle, only the full-length DHP receptor can function as a calcium channel and that the truncated form can only function as a voltage sensor for excitation-contraction coupling. To resolve this issue, we have now constructed a complementary DNA (pC6 delta 1) encoding a protein corresponding to the truncated DHP receptor in skeletal muscle. Expression of pC6 delta 1 in dysgenic myotubes fully restores both excitation-contraction coupling and calcium current, consistent with the idea that a single class of DHP receptors performs both functions.


Exocytotic fusion is activated by Rab3a peptides. Studies of intracellular traffic in yeast and mammalian systems have implicated members of the Rab family of small GTP-binding proteins as regulators of membrane fusion. We have used the patch clamp technique to measure exocytotic fusion events directly and investigate the role of GTP-binding proteins in regulating exocytosis in mast cells. Intracellular perfusion of mast cells with GTP-gamma S is sufficient to trigger complete exocytotic degranulation in the absence of other intracellular messengers. Here we show that GTP is a potent inhibitor of GTP-gamma S-induced degranulation, indicating that sustained activation of a GTP-binding protein is sufficient for membrane fusion. We have found that synthetic oligopeptides, corresponding to part of the effector domain of Rab3a, stimulate complete exocytotic degranulation, similar to that induced by GTP-gamma S. The response is selective for Rab3a sequence and is strictly dependent on Mg2+ and ATP. This suggests that sustained activation of a Rab3 protein causes exocytotic fusion. The peptide response can be accelerated by GDP-beta S, suggesting that Rab3a peptides compete with endogenous Rab3 proteins for a binding site on a target effector protein, which causes fusion on activation.


Potentiation of potassium-evoked noradrenaline and neuropeptide Y co-release by cardiac energy depletion: role of calcium channels and sodium-proton exchange. The role of the cardiac energy status in the potassium-evoked exocytosis of both noradrenaline and the sympathetic co-transmitter neuropeptide Y (NPY) was investigated in the guinea-pig perfused heart. The transmitter release was stimulated by potassium depolarization (10-80 mmol/l) during normoxic perfusion (pO2 > 100 mmHg) in the presence of glucose (11 mmol/l) and at various periods (5-40 min) of cardiac energy depletion. Energy depletion was induced either by anoxia (pO2 < 5 mmHg) or by cyanide intoxication (1 mmol/l), both in combination with glucose-free perfusion. Endogenous noradrenaline and NPY were determined in the coronary venous overflow by high-pressure liquid chromatography combined with electrochemical detection and by radioimmunoassay, respectively. Under normoxic conditions potassium depolarization evoked a co-release of both transmitters [molar ratio 862 (noradrenaline):1 (NPY)] at a threshold concentration of 40 mmol/l potassium. This transmitter overflow was characterized by its dependence on extracellular calcium and calcium influx through voltage-dependent neuronal calcium channels of the N-type. Cardiac energy depletion was accompanied by an acceleration and an enhancement of the potassium-evoked transmitter overflow. In comparison to normoxia, a 10-fold increased transmitter overflow with a comparable molar ratio [709 (noradrenaline:1 (NPY)] was evoked by 40 mmol/l potassium after 10 min of either anoxia or cyanide intoxication. This sensitization to potassium depolarization reached a peak after 10 min of energy depletion and was characterized by a markedly reduced threshold concentration (10 mmol/l potassium).(ABSTRACT TRUNCATED AT 250 WORDS)


Possible involvement of both N- and L-type voltage-dependent Ca channels in adrenergic neurotransmission of canine saphenous veins in low Ca2+ plus tetraethylammonium medium. The involvement of N- and L-type voltage-dependent Ca channels (VDCCs) in adrenergic neurotransmission under the superfusion with 0.25 mM Ca2+ + 20 mM tetraethylammonium (low Ca2+ + TEA) medium has been studied by examining the effects of omega-conotoxin GVIA (omega-CTX) and dihydropyridine antagonists and agonist on transmural nerve stimulation (TNS)-evoked 3H overflow from canine saphenous veins preloaded with [3H]-noradrenaline. Nisoldipine (10 and 30 microM) and nifedipine (30 microM) reduced significantly the TNS-evoked 3H overflow in low Ca2+ + TEA medium, while the two dihydropyridine antagonists failed to suppress it in normal Krebs medium. Bay K 8644 (30 and 100 nM) produced a significant and concentration-dependent enhancement of the TNS-evoked 3H overflow in low Ca2+ + TEA medium. The enhancing effects of Bay K 8644 were antagonized by both 3 microM nisoldipine and 10 microM nifedipine. omega-CTX inhibited markedly the TNS-evoked 3H overflow in both normal Krebs and low Ca2+ + TEA media, the inhibition by omega-CTX being ten times more potent in low Ca2+ + TEA medium. Nisoldipine (30 microM), when combined with 1 nM omega-CTX, produced a further significant inhibition of the TNS-evoked 3H overflow in low Ca2+ + TEA medium. However, no additional inhibition by 30 microM nisoldipine was observed when omega-CTX concentration was raised to 2 nM. In the veins superfused with normal Krebs medium, nisoldipine (30 microM) did not affect the inhibitory effect of 10 nM omega-CTX on the evoked 3H overflow.(ABSTRACT TRUNCATED AT 250 WORDS)


The effect of chronic treatment with peripheral benzodiazepine receptor ligands on behavior and GABAA/benzodiazepine receptors in rat. Rats were twice daily (2 x 10 mg/kg, i.p.) treated for three weeks with the peripheral benzodiazepine (BZ) receptor ligands Ro 5-4864 (4'-chlorodiazepam) and PK 11,195 (1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline-carbox ami de). After the first injection there were no differences between the drug-treated and control animals in behavioral tests. After 10 days treatment, the number of sniffings was increased in Ro 5-4864-treated rats. After the last injection, sniffings and ambulations were decreased in PK 11,195-treated animals. The number of rearings and groomings remained unchanged throughout the treatment, and there were no changes in the results in the elevated plus-maze test. Apparently these compounds are devoid of anxiolytic and anxiogenic effects at moderate doses. The effect of 72 a h withdrawal from the above mentioned chronic treatment on peripheral and central BZ receptors as well as on GABAA receptors was studied with receptor binding techniques using 3H-Ro 5-4864, 3H-flumazenil and 3H-muscimol, respectively, as ligands. The number of GABAA and central BZ receptors was lower after Ro 5-4864 treatment, as was the effect of progesterone-induced stimulation of 3H-muscimol binding. The number of peripheral BZ receptors was decreased after Ro 5-4864 and PK 11,195 treatments in the olfactory bulb but not in the cerebral cortex. The chronic treatment with peripheral BZ receptor ligands Ro 5-4864 and PK 11,195 produced only little behavioral effects. Ro 5-4864, often presented as an agonist of peripheral BZ receptors, was behaviorally inactive.(ABSTRACT TRUNCATED AT 250 WORDS)


Anticonvulsant and sodium channel blocking effects of ralitoline in different screening models. Ralitoline, a thiazolidinone derivative chemically distinct from known antiepileptic drugs, possesses remarkable anticonvulsant properties as demonstrated in various animal models of epilepsy. The efficacy of this compound seems to be comparable or even better than that of conventional antiepileptics. In the present study, the activity of ralitoline was investigated in four seizure models in rodents in order to characterize the anticonvulsant profile of action further. In the maximal electroshock seizure test (mice), this compound showed marked anticonvulsant effects (ED50 2.8 mg/kg i.p.). The efficacy of clinically established anti-epileptics was significantly increased when ralitoline was given as co-medication. In the strychnine seizure test (mice), ralitoline (5 and 10 mg/kg) prolonged the latency of tonic seizures as well as the survival time. On the other hand, in the subcutaneous pentylenetetrazol seizure threshold test (mice), this drug revealed limited protective actions at higher doses and increased the effectiveness of ethosuximide. In unrestrained rats with chronically implanted electrodes, ralitoline (5 mg/kg) significantly reduced the duration of electrically-evoked hippocampal discharges and raised the focal stimulation threshold (10 mg/kg). In the rotorod ataxia test (mice), a TD50 value of 14.5 mg/kg i.p. was determined for ralitoline (protective index TD50/MES-ED50 5.2). With regard to the possible mode of action, whole-cell voltage-clamp experiments on cultured neonatal rat cardiomyocytes showed that ralitoline may act specifically on voltage-sensitive sodium channels. The compound inhibited the fast sodium inward current in a frequency- and voltage-dependent manner. In conclusion, the findings confirm the potent anticonvulsant effects of ralitoline, especially against generalized tonic-clonic and complex partial seizures. Moreover, in combination with antiepileptics, an additive synergism can be found at lower concentrations. Regarding the mode of action, this drug was capable of depressing the fast sodium inward current in cultured heart ventricular cells, suggesting that the local anesthetic properties may be important for the anticonvulsant activity of ralitoline.


[2 patients with brain metastases who became pregnant during phenytoin administration]. Two young women taking phenytoin because of symptomatic brain metastases are described. Both patients, one with end-stage lung cancer and the other in complete remission after intensive chemotherapeutic treatment of a choriocarcinoma, became pregnant while using oral contraceptives in combination with phenytoin. One patient had the child, but died a year after the metastases became apparent, in the other the pregnancy was terminated. When prescribing phenytoin, attention should be paid to fertility--even in patients with end-stage cancer or after intensive, possibly sterilising, chemotherapeutic treatment.


[Mechanism of vitamin B6 regulation of acetylcholine-induced currents in mollusk neurons: pre- and postsynaptic effects]. Vitamin B6 has been studied for the mechanism of its effect on acetylcholine-induced sodium-potassium and chloride currents in E16 neuron of isolated brain of the snail Helix pomatia. The results indicate that the effect of vitamin B6 on acetylcholine-induced currents in postsynaptic neuron E16 is mediated via changes in gamma-aminobutyric acid (GABA) release from a presynaptic neuron and subsequent GABA-induced and cAMP-dependent processes in E16 neuron. It is suggested that effects of vitamin and antivitamin B6 on axons of a presynaptic neuron or neurons may be connected with regulation of GABA synthesis from glutamate catalyzed by the pyridoxal-phosphate-containing enzyme.


[Effect of alpha-latrotoxin on synaptic transmission between identified neurons in Helix central nervous system]. An identified monosynaptic peptidergic contact between identified neurons from the brain of snail Helix pomatia L. has been used to study the effect of alpha-latrotoxin. It was found that being applied extracellularly the toxin evoked an increase of the postsynaptic response amplitude. Intracellular injection of the toxin into the soma of the presynaptic neuron led to a decrease of the postsynaptic current amplitude. Current induced by intracellular injection of cAMP into postsynaptic neuron was also inhibited either by extra- or intracellular application of the toxin. According to previous data which demonstrate similarity between the postsynaptic response and the current which was induced by intracellular injection of cAMP into postsynaptic neuron it has been proposed that the toxin evokes both an increase of the transmitter release from the presynaptic neuron and a decrease of the postsynaptic response amplitude.


[Psychosine-induced changes in neuromuscular transmission and in the structure of the neuromuscular junction in the frog]. A decrease in the amplitude of miniature and evoked end-plate potentials (MEPPs and EPPs) as well as changes in EPP facilitation and depression during frequency stimulation were observed in psychosine-treated m. cutaneous-pectoris of the frog. Electron-microscopic investigation demonstrated severe changes in synaptic Schwann cells embracing motor terminals and disturbances in the inner mesaxon structure of the myelinated parts of motor terminals.


[The excitation of the fibers of the funiculus dorsalis medullae spinalis during the stimulation of different groups of cutaneous and muscle nerve fibers in the cat]. Electric stimulation of various groups of fibres of cutaneous and muscle nerve of cat has been studied for its effect on action potentials in the gray dorsal column fibres, Registration was performed at the level L2--L3 from ipsi- and contralateral dorsal columns, using needle electrodes. Action potentials of dorsal columns, arisen by stimulation of cutaneous nerves, had a more complex form than those of stimulated muscle nerves. Nonmyelinated fibres of a cutaneous nerve are shown to relate to those of dorsal columns. Excitation of high-threshold A- and C-fibres activates the most fast-conducting fibres of dorsal columns. When a stimulus was applied to all fibres of the cutaneous nerve, the action potentials with conduction velocities of 146-0.24 m/s were recorded in dorsal columns. It was shown that such conduction velocities remained in dorsal columns to level C7. Stimulation of muscle nerves excited only myelinic fibres of dorsal columns, the conduction velocities ranging from 90 to 2.3 m/s. By alternating stimulation of either nerve with a 30-300 ms interval we decreased the action potential amplitude of the nerve that was the second to be stimulated. It is likely be related to convergence of the cutaneous and muscle nerve inputs in the spinal cord on the same neurons. A suggestion is made that faster transfer of high-threshold cutaneous signals in dorsal column are associated with the necessity of rapid information about damaging stimulation.


Evaluation of squamous cell carcinoma antigen (SCC-Ag) in the diagnosis and follow-up of patients with non-small cell lung carcinoma. The usefulness of squamous cell carcinoma (SCC) antigen as a tumor marker was investigated in 72 patients with histologically verified non-small cell lung carcinoma (NSCLC). Increased level of SCC-Ag was observed in 41%, mostly in patients with squamous cell carcinoma (69%). Positive serum SCC-Ag was correlated with lymph node metastases and with the stage of disease. The positive rate of SCC-Ag observed in patients without and with nodal metastases was 52.9% and 84.2%, respectively. Positive SCC-Ag level was observed in 50% of Stage I, 71.4% of Stage II and 78.9% of Stage III patients with squamous cell carcinoma of the lung. The study proved that preoperative SCC-Ag determination in patients with squamous cell carcinoma of the lung and the course of levels of this marker during postoperative follow-up was of importance. A high preoperative and postoperative SCC-Ag value suggested a worse prognosis.


Value of CEA and SCC-Ag in bronchoalveolar lavage (BAL) and serum of patients with lung carcinoma. To evaluate the diagnostic usefulness of simultaneous determinations of carcinoembryonic antigen (CEA) and squamous cell carcinoma antigen (SCC-Ag), we studied 25 patients with lung carcinoma and 12 with nonmalignant lung diseases. The measurements were made in serum and bronchoalveolar lavage (BAL). The results showed that positive rates with lavage CEA and SCC-Ag in lung carcinoma patients were higher in comparison with those markers in serum. The combination of lavage CEA and SCC-Ag taken together with the results of bronchoscopy (histology and cytology) showed the highest discriminating power between malignant and nonmalignant lung diseases. The sensitivity of bronchoscopy increased from 48 to 84% with at least 1 positive marker. It appears that the simultaneous determination of CEA and SCC-Ag levels in serum and BAL in lung carcinoma patients may be of considerable importance in diagnosis.


An attempt to induce formation of antibodies against endogenous retrovirus BP 6 in syngenic rats. An attempt was made to induce production of antibodies against C-type endogenous rat retrovirus BP 6. Syngenic Lewis rats were immunized with viable tumor cells, induced with benzo(a)pyrene, continuously producing BP 6 virus. By use of immunoblotting technique, neither short- nor long-term immunization did cause formation of any detectable amounts of antibody against structural proteins of the virus. On the other hand, in immunoblotting, antibodies arised in rats immunized with purified mouse leukemia virus have been found to cross-react with endogenous rat retrovirus.


["Abducens neuromyotonia" with partial oculomotor paralysis]. Paroxysmal involuntary spasms of extraocular eye muscles which can lead to reversible pathological eye positions and limitations of eye movements are etiologically heterogenous. Despite the diagnostic difficulty, they are important as a neurological sign because of the usually good response to treatment. We report on a patient with the unusual combination of ocular neuromyotonia with brief paroxysmal tonic lateral deviation of the left eye and a concomitant partial third nerve palsy. The paroxysmal episodes disappeared with carbamazepine therapy. Possible pathomechanisms are discussed.


A randomized trial of two doses of granisetron in the treatment of chemotherapy-induced emesis. Dutch results within a multinational study. Granisetron is a new serotonin-receptor antagonist with considerable activity in preclinical models and early clinical studies against drug-induced nausea and vomiting. In a randomized, double-blind trial, two dose levels of granisetron were compared with regard to their efficacy and safety if given to patients receiving emetogenic chemotherapy with or without cisplatin. The present paper reports the Dutch experience with 125 patients included in this international trial. The two dose levels (40 and 160 micrograms/kg given once i.v. prior to chemotherapy) were equally effective in preventing acute emesis and nausea (within the first 24 h); in the group receiving cisplatin doses of 50 mg/m2 or more, 39% of patients had a complete response (no vomiting and mild nausea at most), with a complete response rate of 82% in the patients receiving moderately emetogenic chemotherapy. Sixty-three percent of patients receiving highly emetogenic chemotherapy with a complete response within 24 h lost this response during the next 6 days, as did 20% of the other patients. Headache was the most frequently reported adverse event (18%), followed by constipation (6%) and dizziness (4%). All adverse events were mild and occurred equally frequently at both dose levels. Granisetron at 40 micrograms/kg i.v. given once is effective in the prevention of acute chemotherapy-induced emesis and nausea, in particular in patients receiving moderately emetogenic therapy.


Low molecular weight heparin (CY-216) versus unfractionated heparin in chronic hemodialysis. In 14 patients undergoing chronic hemodialysis, we investigated the safety and efficacy of the low molecular fragment (CY-216) in comparison to unfractionated heparin (UFH) in the prevention of clotting in the extracorporeal circuit (ECC). In this study, 168 hemodialysis sessions were undertaken with UFH in 2 bolus doses (5,437 +/- 1,477 SD IU) and 231 with CY-216 in a single bolus dose [initial dose 150 anti-Xa U Institut Choay (IC)/kg]. There were no clots in the bubble trap in any UFH sessions, and 14.8% had coagulated fibers in the dialyzer. Clotting in the bubble trap was observed in 2 CY-216 sessions (0.8%) and coagulated fibers in 22.6% of the sessions. At the end of the study, the mean dose of CY-216 was 250 anti-Xa UIC/kg but a dose of 350 anti-Xa UIC/kg was needed in the 2 patients treated by recombinant human erythropoietin. Anti-Xa levels at the end of the runs were higher (0.47 +/- 0.1 U/ml) in the CY-216 group than in the UFH group (0.28 +/- 0.1 U/ml). There was a correlation between anti-Xa levels and efficacy in the CY-216 group. An anti-Xa activity above 0.4 U/ml was needed in order to minimize thrombus formation. Antithrombin III-protease complexes (ATM) and D dimer fibrin derivatives (D dimer) were used as thrombotic markers but they were of little value for the detection of fibrin formation in the ECC. Our findings suggest that CY-216 administered as a single bolus dose seems to be of similar effectiveness to UFH.


Specific receptors for beta-endorphin on mesangial cells. beta-Endorphin is an endogenous opioid considered to be a modulator of immune injury. We studied the binding of [125I]beta-endorphin on cultured rat mesangial cells at 4 and 37 degrees C. The results were analyzed by computer program (Ligand). Incubation of rat mesangial cells with unlabeled beta-endorphin displaced [125I]beta-endorphin in a concentration-dependent manner. The binding of [125I]beta-endorphin was not affected by either opiate agonists or antagonists. Saturation studies at 37 degrees C revealed that beta-endorphin binding was time dependent. Binding studies revealed the presence of a single class of high-affinity binding sites with an apparent Kd of 15.3 nM. The number of receptor sites was calculated as 8.48 x 10(5) sites/cell. Mesangial cells exposed to beta-endorphin (10(-6) M) for 48 h showed enhanced incorporation of [3H]thymidine when compared to untreated cells (control, 23,228 +/- 2,778 cpm/well vs. beta-endorphin, 44,887 +/- 4,259 cpm/well; p less than 0.01). Our results show that mesangial cells carry a specific receptor for beta-endorphin which may be linked to proliferation of mesangial cells.


Skin lesions in kidney transplant recipients. A complete examination of the skin was performed in 53 kidney transplant recipients. Cutaneous lesions were detected in almost all patients. Papillomavirus infections, premalignant and malignant lesions represent the greatest risk for these patients. Our study underlines the importance of a continuous observation to facilitate early diagnosis and treatment of these lesions.


In situ hybridization analysis of cytomegalovirus and adenovirus DNA in immunoglobulin A nephropathy. Viruses are thought to play a role in the occurrence of IgA nephropathy. In fact, cytomegalovirus (CMV) antigens have been detected in the glomerular mesangium. To clarify this relationship, we used in situ hybridization with biotin-labeled DNA probes of CMV and adenovirus (AV) in 40 patients with IgA nephropathy to determine the presence or absence of virus in affected renal tissue. Renal tissue DNA from these patients did not hybridize with the CMV or AV probes. Our results fail to support the theory that consecutive regional renal infections with CMV and/or AV are involved in the pathogenesis of IgA nephropathy.


Neural tissue within anterior pituitary tumors generated by oncogene expression in transgenic mice. Pituitary tumorigenesis occurs in a transgenic line of mice, alpha-T7, which carries a hybrid transgene composed of the 5' flanking region of the human glycoprotein hormone alpha-subunit gene (1.8 kb) linked to the coding region of the SV40 T-antigen gene (alpha-Tag). Tumor foci were identified within the anterior pituitary of both male and female transgenic mice. In addition to a parenchyma with hypertrophied endocrine cells, mostly of the gonadotrope lineage, we here report the unexpected presence of neural tissue within the anterior pituitary, either as foci as large as 1.0 mm in diameter or greater, or in delicate bundles ramifying amongst the granulated parenchymal cells. Areas richest in neural tissue frequently were associated with tumor tissue composed of giant cells of three varieties, all with electron-lucent cytoplasm and similar organellar distribution including small secretory granules (80-160 nm diameter). In type I cells, the secretory granules were aligned at the plasma membrane; in type II cells, the secretory granules were distributed throughout the cytoplasm; type III cells formed colloid-filled follicles and their secretory granules rarely exceeded 100 nm diameter. These giant cells frequently had bizarre pleomorphic nuclei intensely immunopositive for T-antigen and cytoplasm which was lightly immunopositive for alpha-subunit, and immunopositive either for the LH-beta or TSH-beta subunits. Neural tissue contacted the normal granulated parenchymal cells directly, i.e., without a basal lamina or any connective tissue intervening, but only rarely formed synaptoid junctions with these granulated cells. Synaptoid junctions containing round, smooth vesicles, as well as dense core vesicles, were numerous between the neural processes themselves and between the neural tissue and the giant cells of the tumor tissue. These data suggest that in alpha-T7 transgenic mice the giant cells represent highly transformed gonadotropes or thyrotropes, and that a neurotrophic factor may be expressed by these transformed pituitary parenchymal cells.


Effect of cortisol infusion on the pituitary-adrenal axis of the hypothalamo-pituitary-disconnected fetal sheep. In order to determine whether cortisol acts directly at the level of the fetal pituitary to promote pars distalis corticotroph maturation, we have infused cortisol into the hypothalamo-pituitary-disconnected (HPD) fetal sheep from 111 to 117 days of gestation. In this study we have measured fetal plasma cortisol and immunoreactive adrenocorticotrophic hormone (ir-ACTH) concentrations between 105 and 116 days of gestation, and we have determined the proportions of adult- and fetal-type corticotrophs in the pars distalis of catheter control fetuses and in HPD fetuses infused with either saline (HPD+SAL) or cortisol (2 mg/day; HPD+F). The fetal plasma cortisol concentrations did not change significantly following HPD. The mean fetal plasma cortisol concentration between 113 and 116 days was threefold higher in the HPD+F fetuses than that measured in HPD fetuses. Following HPD, fetal plasma ir-ACTH concentrations were significantly higher than in catheter control fetuses. Despite the significant elevation in plasma cortisol concentrations in HPD+F fetuses between 113 and 116 days, plasma ir-ACTH concentrations were not different in these fetuses from HPD fetuses infused with saline. At 117 days of gestation in HPD+F fetuses, the proportion of fetal-type corticotrophs in the pars distalis was significantly less than in the HPD+SAL fetuses; however, there was no significant change in the proportion of adult-type corticotrophs in the pars distalis following cortisol infusion. We have shown that cortisol has a direct trophic effect on the maturation of the pars distalis corticotrophs; however, the full maturation of these cells requires an intact hypothalamo-pituitary axis. These findings demonstrate the importance of the fetal hypothalamus in anterior pituitary corticotroph maturation during the last third of gestation.


Control of proglucagon-derived peptide synthesis and secretion in fetal rat hypothalamus. The hypothalamus has the highest concentration of proglucagon-derived peptides (Pgdp's) in the brain, however, the control of the synthesis and secretion of these peptides is not understood. The goal of our studies was to examine in detail the regulation of synthesis and secretion of Pgdp's in the hypothalamus. Hypothalamic cultures were prepared from fetal rats on day 19-21 of gestation and Pgdp's in media and cells were determined by radioimmunoassay after treatment with test agents. Dibutyryl cyclic AMP or forskolin, activators of protein kinase A, markedly stimulated both Pgdp synthesis (by 5-fold) and secretion (by 10-fold) after 24 h of treatment (p < 0.05). The effects of protein kinase A stimulation on Pgdp's in the hypothalamus were greater than seen in our previous studies with the Pgdp-producing pancreatic A and intestinal L cells. Therefore there are tissue-specific differences with regard to the magnitude of the response of Pgdp's to protein kinase A stimulation. Consistent with an involvement of protein kinase A in hypothalamic Pgdp synthesis and secretion, somatostatin-14, an inhibitor of protein kinase A, was found to inhibit Pgdp synthesis and secretion in a dose-dependent fashion (p < 0.05). Phorbol myristate acetate (PMA), a stimulator of protein kinase C, did not significantly affect the synthesis or secretion of Pgdp's at 6 h, but significantly stimulated Pgdp secretion after 24 h (p < 0.05). The inactive phorbol ester, phorbol triacetate was without effect on Pgdp synthesis or secretion after 24 h of incubation (p > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)


Monosodium glutamate-induced reductions in hypothalamic beta-endorphin content result in mu-opioid receptor upregulation in the medial preoptic area. Estradiol valerate (EV) treatment in the rat induces a lesion of the hypothalamic arcuate nucleus, resulting in significant decreases in hypothalamic beta-endorphin. In addition, the EV treatment causes a selective increase in mu-opioid binding in the medial preoptic area (MPOA). Since beta-endorphin neurons located in the arcuate nucleus project extensively to the MPOA, we have hypothesized that the EV-induced loss of these afferents induces a compensatory upregulation of mu-opioid receptors in opioid target neurons. In order to test this hypothesis, we have utilized monosodium glutamate (MSG) treated animals as a model of beta-endorphin cell loss and hence of beta-endorphin deafferentation of the MPOA. Neonatal MSG treatment has been shown to result in the destruction of 80-90% of arcuate neurons accompanied by pronounced decreases in beta-endorphin concentrations in both arcuate nucleus and MPOA. mu-Opioid binding sites were radioautographically labeled in sections from the MPOA of sham- and MSG-injected animals using the methionine enkephalin analogue 125I-FK 33-824 and quantitated by computer-assisted densitometry. The remainder of the hypothalamus of these same animals was utilized for the determination of the beta-endorphin concentration. The hypothalami of rats treated with MSG exhibited 62% (p < 0.01) less beta-endorphin than saline-injected controls. In addition, the mean mu-opioid-binding densities in the MPOA were 24% (p < 0.05) above controls in the MSG-treated group.(ABSTRACT TRUNCATED AT 250 WORDS)


Histamine- and stress-induced secretion of ACTH and beta-endorphin: involvement of corticotropin-releasing hormone and vasopressin. Histamine (HA) stimulates the release of the pro-opiomelanocortin (POMC)-derived peptides ACTH, beta-endorphin (beta-END), beta-lipotropin and alpha-melanocyte-stimulating hormone, and HA is involved in the mediation of the stress-induced release of these peptides. The effect of HA is indirect and may involve the hypothalamic regulating factors, corticotropin-releasing hormone (CRH) and/or arginine-vasopressin (AVP). We studied the effect of immunoneutralization with specific antisera against CRH or AVP on the response of ACTH and beta-END to HA, restraint stress, CRH, AVP or a posterior pituitary extract in male rats. Intracerebroventricular infusion of HA (34-540 nmol) increased the plasma levels of ACTH and beta-END immunoreactivity (beta-ENDir) in a dose-dependent manner. Pretreatment with antiserum to CRH or AVP prevented the ACTH response to 270 nmol HA and inhibited the beta-ENDir response by 30-60%. One to five minutes of restraint stress caused an increase in the plasma levels of ACTH and beta-ENDir. The increase was dependent on the duration of stress exposure. Pretreatment with CRH antiserum abolished the ACTH response to 5 min of restraint stress and inhibited the beta-ENDir response by 60%. Immunoneutralization with AVP antiserum had only half the inhibitory effect of that seen with CRH antiserum. CRH (100 pmol i.v.) increased the plasma levels of ACTH and beta-ENDir. This effect was abolished by pretreatment with CRH antiserum, whereas pretreatment with AVP antiserum prevented the CRH-induced ACTH release and inhibited the beta-ENDir response by 50%. AVP (24-800 pmol i.v.) stimulated ACTH and beta-ENDir in a dose-dependent manner. CRH and AVP antisera each prevented the effect of AVP (800 pmol) on ACTH secretion, whereas the beta-ENDir response to AVP was only inhibited by about 60% by the antisera. An extract of the posterior pituitary gland administered in a dose corresponding to 0.15 or 0.5 pituitary equivalents had no effect on ACTH secretion, while 1.0 pituitary equivalent increased the ACTH concentration in plasma. This effect was abolished by AVP antiserum. The posterior pituitary extract caused a dose-dependent rise in plasma beta-ENDir which might be due to an unavoidable contamination of the posterior pituitary extract by a small amount of beta-END from the intermediate lobe. Consistent with this view, AVP antiserum had no effect on the rise in the plasma concentration of beta-ENDir following administration of the posterior pituitary extract.(ABSTRACT TRUNCATED AT 400 WORDS)


Inhibition of the nicotinic acetylcholine response by serotonergic and muscarinic agents in chick ciliary ganglion neurones. Chick ciliary ganglion neurones were investigated by whole cell voltage clamp recordings. The ACh- or nicotine-induced inward current was partially inhibited by perfusing the neurones with 5-HT. This effect was rapid (< or = 1 min), dose-dependent (50-1000 microM) and quickly reversible. The selective 5-HT1A agonist 8-OH-DPAT (10 microM) reduced the nicotinic ACh response more potently, irrespective of the absence or presence of propranolol (1 microM), a known 5-HT1A antagonist. Other serotonergic antagonists, like ICS 205-930 (1 microM), mianserin (10 microM) and methysergide (10 microM), also failed to antagonize the 5-HT-mediated decrease in the nicotinic response. Muscarine (50 microM) did not affect the nicotine-induced inward current but the muscarinic agonist oxotremorine (10 microM) also decreased the nicotine-induced inward current. Atropine, at small concentrations failed to block this effect but caused some reduction of the ACh response itself at larger (1-10 microM) concentrations. It is suggested that 5-HT may modulate synaptic transmission in ciliary ganglion neurones in vivo. The site of action of 5-HT, oxotremorine and atropine might be at or close to the ACh receptor complex, because of the fast onset and reversibility of the effects and lack of specificity for structurally different drugs.


Kappa 3 receptors and levorphanol-induced analgesia. Levorphanol is a widely used opiate analgesic. Although structurally related to morphine, levorphanol has high affinity for a number of receptor subtypes, including both kappa 1 and kappa 3. Prior reports had implicated a kappa component of levorphanol-induced antinociception. Evidence is now presented suggesting that levorphanol-induced analgesia is produced by a mixture of mu and kappa 3 mechanisms. Levorphanol was a potent analgesic in the tail-flick assay, when given systemically, spinally or supraspinally. Isobolographic analysis of the combined administration of levorphanol, spinally and supraspinally implied synergistic interactions. Naloxonazine reduced levorphanol-induced analgesia, implicating a role for mu1 receptors. The kappa 1 antagonist nor-binaltorphimine at a dose which reversed analgesia induced by U50,488H did not antagonize levorphanol-induced analgesia. Additional studies revealed no cross tolerance in either direction, between levorphanol with the kappa 1 analgesic U50,488H. Together, these results strongly argue against a role for kappa 1 receptors in levorphanol-induced analgesia. However, mice tolerant to the kappa 3 analgesic, naloxone benzoylhydrazone (NalBzoH), showed cross tolerance to levorphanol, implying a role of kappa 3 mechanisms in levorphanol-induced analgesia.


Polyamines modulate the binding of GABAA-benzodiazepine receptor ligands in membranes from the rat forebrain. The effects of spermine, spermidine and putrescine on the binding of the GABAA-benzodiazepine receptor complex were examined in the hippocampus and frontal cortex membranes of the rat. The results demonstrated modulatory effects of polyamines on the binding of diazepam and flunitrazepam but not on that of GABA, muscimol and Ro 15-1788. When membranes were prepared without detergent, the polyamines enhanced the binding of diazepam. However, while the binding capacity increased after homogenization in the presence of the non-ionic detergent Triton X-100, the polyamines did not enhance the binding but inhibited the binding of diazepam and flunitrazepam at greater concentrations. Considered together with other studies, the present findings indicate that polyamines can modulate the binding characteristics of several different neurotransmitter receptor-ionophore complexes.


Effect of acute and chronic administration of ceronapril on angiotensin converting enzyme in plasma, kidney, lung, brain regions and cerebrospinal fluid of rats. Angiotensin converting enzyme (ACE) in brain, cerebrospinal fluid (C.S.F.) and peripheral tissues was studied ex vivo after oral administration of ceronapril (SQ 29,852) to male Sprague-Dawley rats. Angiotensin converting enzyme in tissue was measured by in vitro autoradiography or enzymatic assay. In in vitro experiments, ceronapril inhibited ACE in slices of brain with an IC50 of approximately 34 nM, as measured by in vitro autoradiography. In C.S.F. ACE was inhibited with an IC50 of approximately 34 nM, as assessed by a fluorimetric enzyme assay. Ceronapril (100 mg/kg, p.o.) inhibited ACE in plasma, kidney and lung rapidly (3 hr) after administration. Inhibition of ACE in kidney lasted up to 48 hr after administration of ceronapril, whereas the activity of ACE in plasma and lung recovered rapidly (8 hr). In lung and plasma ACE was increased at 72 hr after administration. Therefore, induction of ACE in plasma and lung by the drug may partly obscure the acute inhibition and may contribute to the different time-course of inhibition of ACE from kidney. Ceronapril inhibited ACE in vascular organ of the lamina terminals (OVLT) and subfornical organ (SFO) of the brain slowly (onset at 8 hr) but persistently (from 24 to 48 hr). However the drug did not inhibit ACE in structures of the brain within the blood-brain barrier, such as the caudate-putamen, choroid plexus, globus pallidus, supraoptic nucleus and paraventricular nucleus of the hypothalamus. In C.S.F. ACE was not detectably inhibited by ceronapril but was increased at 72 hr.(ABSTRACT TRUNCATED AT 250 WORDS)


Intraventricular endothelin-1 uncouples the blood flow: metabolism relationship in periventricular structures of the rat brain: involvement of L-type calcium channels. Endothelin-1 (ET) produces contraction of cerebral resistance vessels in vitro and in situ, but also is neuroactive causing increases in tissue energy metabolism as measured by [14C]deoxyglucose autoradiography in the intact rat brain. ET may, therefore, disengage the normally tight linkage between cerebral blood flow and tissue metabolism. Using anatomically rigorous autoradiographic and imaging techniques to measure focal blood flow in anesthetized, ventilated rats, we found that intraventricular injection of 9 pmol of ET reduced rates of perfusion by an average of 29% (compared to a saline-injected condition) in 6 individual periventricular structures bordering the injected lateral ventricle. A significant vasoconstrictor effect (41% decrease in blood flow) also occurred in the ipsilateral choroid plexus after ET injection, despite its increased rate of glucose metabolism. We employed a hydrogen clearance method to monitor rates of blood flow serially within the periventricular margin of the caudate nucleus after intraventricular injection of the dihydropyridine calcium-channel antagonist, nimodipine (72 nmol), or 9 pmol ET, alone and in sequence. Nimodipine increased caudate blood flow (by 47%) and prevented the vasoconstriction produced by ET. The results indicate that ET causes vasoconstriction in penventricular brain structures and choroid plexus even in the presence of substantial increases in glucose metabolism. The simultaneous stimulation by intraventricular ET of tissue hypermetabolic and vascular constrictor mechanisms, leading to a net reduction of periventricular blood flow, is mediated, at least in part, by dihydropyridine-sensitive calcium L-channels.


Supraspinal antinociception produced by [D-Met2]-FMRFamide in mice. The ability of Phe-Met-Arg-Phe-NH2 (FMRFamide) or [D-Met2]-FMRFamide to produce antinociception in mice, or to block morphine-induced antinociception, was examined using the tail-flick and tail-immersion (55 degrees C) tests. [D-Met2]-FMRFamide dose-dependently produced antinociception following intracerebroventricular (i.c.v.) administration with ED50 values (95% confidence limits) of 5.0 (2.2-7.2) and 12.8 (8.1-19.9) micrograms in the tail-flick and tail-immersion tests, respectively. FMRFamide did not produce a maximal effect in the tail-flick test. Naloxone (administered s.c. 20 min prior to the i.c.v. administration of [D-Met2]-FMRFamide) dose-dependently attenuated [D-Met2]-FMRFamide-induced antinociception. The shift in the [D-Met2]-FMRFamide dose-response curve was parallel and a pA2 value for naloxone of 6.3 +/- 0.3 was determined from a Schild plot analysis. Mice made tolerant to the antinociceptive effect of morphine were cross-tolerant to the antinociceptive effect of [D-Met2]-FMRFamide. FMRFamide and [D-Met2]-FMRFamide both produced rightward, parallel shifts of the morphine antinociceptive dose-response curve. The findings that [D-Met2]-FMRFamide both elicited naloxone-sensitive antinociception and attenuated morphine-induced antinociception are consistent with the view that FMRFamide-related peptides (FaRPs) are weak agonists at opioid receptors and, further, appear to reconcile the apparently chimeric agonist and antagonist properties of these peptides observed in vivo.


Double adenomas of the pituitary: a clinicopathological study of 11 tumors. Of more than 3000 cases of surgically removed pituitary adenomas, 11 were defined as "double adenomas," i.e., 2 morphologically or immunocytologically distinct tumors. In 8 cases, the lesions exhibited differing histological features and immunophenotypes; in 2 specimens, distinct ultrastructural features were noted as well. In another instance, despite histological and immunocytological uniformity, the two neoplastic components demonstrated distinct ultrastructure. In yet another case, the two adenomas were consecutively removed; despite similar histological features, they differed in immunocytological and ultrastructural characteristics. Last, in one case, the adenoma was histologically uniform, but a portion of the mass exhibited immunoreactivity by ultrastructural features distinct from those of the remainder of the lesion. Hormonal excess attributed to both tumors could be correlated with endocrine manifestations in two cases. Double adenomas of the pituitary occur infrequently. In routine histological sections of surgical material, they are often difficult if not impossible to identify. Presented herein are clinical and endocrinological data on 10 cases of double pituitary adenomas correlated with morphological and immunocytochemical results. The literature regarding multiple adenomas is reviewed as are the diagnostic and therapeutic difficulties associated with these rare lesions.


Adrenocorticotropic hormone-secreting pituitary tumor associated with pregnancy: case report. A patient with an adrenocorticotropic hormone-secreting pituitary adenoma diagnosed at the same time as pregnancy is reported. Treatment was by transsphenoidal tumor resection, which has only been described once previously in such a case. Treatment rationale is discussed, and transsphenoidal tumor resection is recommended as the therapy of choice.


Early experience with the Gill Thomas Locator for computed tomography-directed stereotactic biopsy of intracranial lesions. The Gill Thomas Locator is a stereotactic adaptor for the Brown-Roberts-Wells and Cosman-Roberts-Wells systems. It is a noninvasive device that relies on temporary fixation to the maxillary teeth. A series of 20 patients have had stereotactic biopsies with this system. A diagnostic biopsy was obtained in 19 cases. The frame was well tolerated, accurately relocatable, and allowed computed tomographic scanning and surgery to be conducted at different times.


The demonstration of glomus tumours by subtraction MRI. Thirteen patients with 14 glomus tumours have been examined by subtraction gadolinium-enhanced magnetic resonance imaging (MRI), with T1-weighted MR sequences before and after intravenous gadolinium-DTPA. To eliminate movement between subtraction pairs, the patient remains in the tunnel of the imager during administration of the contrast medium, and the venepuncture is made into the dorsum of the foot. The effect of the subtraction process is to remove the NMR signal from the final image so that the photographic densities recorded are dependent on the vascularity of the tissue concerned, normal or abnormal. A particular advantage is the removal of fat signal: the low vascularity of adipose tissue ensures that it is recorded as of minimal density. The extent of skull base glomus tumours has been shown optimally by this technique. Subtraction can also help differentiate glomus tympanicum from glomus jugulare lesions, which may be of crucial importance when deciding the surgical approach. In addition to diagnosis, the technique is also important post-operatively, when imaging is needed to show residual or recurrent tumour and to monitor the effects of radiotherapy.


Enhancement of calcium currents in rat hippocampal CA1 neurons induced by kindling epileptogenesis. Kindling of the Schaffer collaterals in the dorsal hippocampus of the rat induced an epileptogenic focus in area CA1. Pyramidal neurons were acutely isolated from this area in fully kindled rats one day after the last class five generalized seizure. Calcium currents were measured in these cells under the whole-cell patch voltage-clamp condition after blockade of sodium and potassium currents. Voltage-dependent calcium currents were activated by depolarizing voltage steps from different prepulse potentials. Calcium currents activated at 0 mV consisted of a sustained component and two voltage-dependent inactivating components. Current inactivation was fitted with two exponentials (time-constants of 13 and 72 ms) and a constant. When cells from kindled rats were compared with those from controls, the amplitudes of the slow-inactivating and the sustained component were significantly enhanced by 36% and 39%, respectively; the fast inactivating current showed only a small enhancement. Inactivation kinetics, time-to-peak and voltage dependency of activation and steady-state inactivation were unchanged. Shape and size of the analysed cells from kindled rats were not different from those in controls. We concluded that an increased specific calcium conductance of as yet unknown origin underlies the larger current. The magnitude of the observed changes is such that it will considerably increase calcium influx and consequently raise intracellular calcium concentration during tetanic stimulation and subsequent periods of paroxysmal activity. This increase will modulate calcium-dependent factors that regulate neuronal excitability and may lead to the enhanced excitability found in kindled tissue.


Arachidonic acid and its acyclic derivatives regulate short-term plasticity of the cholinoreceptors of neurons of the edible snail. The influence of eicosanoids on the dynamics of the extinction of the inward current, induced by repeated iontophoretic applications of acetylcholine to the soma has been demonstrated in identified RPa3 and LPa3 neurons of the edible snail by means of bielectrode recording of the membrane potential. The extracellular action of arachidonic acid (50-100 mumole/l) intensifies the extinction. Quinacrine (100-600 mumole/l), an inhibitor of phospholipase A2, which decreases the content of arachidonic acid in the cells, acts ambiguously. Nordihydroguaiaretic acid (3-10 mumole/l), which is an inhibitor of the lipoxygenase oxidation of arachidonic acid, attenuates the extinction. Indomethacin (10-50 mumole/l), a blocker of cyclooxygenase oxidation of arachidonic acid, does not influence extinction. All of the compounds investigated decrease the amplitude of the inward current induced by acetylcholine. The results obtained make it possible to hypothesize that arachidonic acid and its acyclic metabolites, which are formed as a result of lipoxygenase oxidation, regulate short-term plasticity of the cholinoreceptors of neurons of the edible snail. The cyclic eicosanoids which are formed during the cyclooxygenase oxidation of arachidonic acid do not exert a regulatory effect on the plasticity of the cholinoreceptors.


The endoplasmic reticulum of Purkinje neuron body and dendrites: molecular identity and specializations for Ca2+ transport. Immunofluorescence and immunogold labeling, together with sucrose gradient separation and Western blot analysis of microsomal subfractions, were employed in parallel to probe the endoplasmic reticulum in the cell body and dendrites of rat cerebellar Purkinje neurons. Two markers, previously investigated in non-nerve cells, the membrane protein p91 (calnexin) and the lumenal protein BiP, were found to be highly expressed and widely distributed to the various endoplasmic reticulum sections of Purkinje neurons, from the cell body to dendrites and dendritic spines. An antibody (denominated anti-rough-surfaced endoplasmic reticulum), which recognized two membrane proteins, p14 and p40, revealed a similar immunogold labeling pattern. However, centrifugation results consistent with a widespread distribution were obtained for p14 only, while p40 was concentrated in the rough microsome-enriched subfractions. The areas enriched in the inositol 1,4,5-triphosphate receptor and thus presumably specialized in Ca2+ transport (stacks of multiple smooth-surfaced cisternae; the dendritic spine apparatus) also exhibited labeling for BiP and p91, and were positive for the anti-rough-surfaced endoplasmic reticulum antibody (presumably via the p14 antigen). Additional antibodies, that yielded inadequate immunocytochemical signals, were employed only by Western blotting of the microsomal subfractions, while the ryanodine receptor was studied by specific binding. The latter receptor and the Ca2+ ATPase, known in other species to be concentrated in Purkinje neurons, exhibited bimodal distributions with a peak in the light and another in the heavy subfractions. A similar distribution was also observed with another lumenal protein, protein disulfide isomerase. Taken as a whole, the results that we have obtained suggest the existence in the endoplasmic reticulum of Purkinje neurons of two levels of organization; the first identified by widespread, probably general markers (BiP, p91, possibly p14 and others), the second by specialization markers, such as the inositol 1,4,5-triphosphate receptor and, possibly, p40, which appear restricted to areas where specific functions appear to be localized.


The monosynaptic connection: modulating influence of opioid peptides on the plasticity of presynaptic neurons and identified synapses. An investigation of the effect of opioid peptides (leucine-enkephalin and methionine-enkephalin) on the plastic properties of the system of monosynaptically connected LPa7-LPa3 and RPa3, and LPa8-LPa3 and RPa3, neurons in the brain of the edible snail was carried out. It was demonstrated that all three elements in the system under investigation (the presynaptic neuron, the postsynaptic neuron, and the synapse) display the same type of plasticity, i.e., habituation to rhythmic stimulation. The enkephalins exert a modulating effect on the plastic properties of the presynaptic neuron and synapse: they slow down the habituation of the presynaptic neuron in response to intracellular stimulation and the development of habituation at a level of the synapse as well. However, the changes in the character of the postsynaptic response in the presence of enkephalins are not the direct consequence of their influence on the plastic properties of the presynaptic neuron. In addition, the enkephalins decrease the efficiency of synaptic transmission in this system: they decrease the duration of the EPSP in the postsynaptic neuron.


Atrial natriuretic peptide increases cyclic guanosine monophosphate immunoreactivity in the carotid body. The mammalian carotid body is a peripheral arterial chemoreceptor organ involved in the regulation of respiration, and in the modulation of blood pressure through reflex control of peripheral vascular resistance and cardiac output. In addition to its responsiveness to blood gases, the organ is also sensitive to hyperosmotic solutions, and we have recently shown that a systemic hormonal regulator of natriuresis and diuresis, atrial natriuretic peptide, is a potent inhibitor of chemoreceptor activity evoked by hypoxia in the cat carotid body. The present study demonstrates atrial natriuretic peptide immunoreactivity in type I cells of the carotid body, and shows further that a biologically active atrial natriuretic peptide fragment, atriopeptin III, increases cyclic guanosine monophosphate immunoreactivity in type I cells in a dose-dependent manner. Moreover, double-labeling techniques demonstrate co-existence of atrial natriuretic peptide immunoreactivity with the atriopeptin III-enhanced cyclic guanosine monophosphate reaction product. These findings indicate the probable existence of atrial natriuretic peptide receptors coupled to membrane-bound guanylate cyclase on the parenchymal type I cells. Our findings support the view that cyclic guanosine monophosphate functions as a second messenger in this organ, and may serve as a functional activity marker in identifying type I cells which respond to atrial natriuretic peptide.


Localization of mu opioid receptors on the membranes of nerve endings and tanycytes in the guinea-pig median eminence by electron microscopic radioautography. The high density of opioid-containing nerve endings in the median eminence together with the absence of direct effects of opioids upon pituitary suggest a local action of opioids in the median eminence. The aim of this work was to address the occurrence of mu-opioid binding sites in the median eminence at the electron microscopic level, using the highly selective radioligand [125I]FK 33-824. mu-Opioid receptors were labeled in vitro on slightly prefixed slices of mediobasal hypothalamus. The labeling was essentially detected in the external part of the median eminence. Most of the silver grains overlaid membrane appositions. Two overall types of appositions were concerned: nerve terminal-nerve terminal or nerve terminal-tanycyte. Detailed analysis of the silver grain distribution indicated that mu receptors were observed on membranes of different types of nerve endings but also of tanycytes. All the binding sites were localized out of synaptic junctions since the median eminence is totally devoid of these structures. Our results suggest that in the median eminence, opioid peptides have a paracrine and/or autocrine action occurring at least via mu receptors located on nerve terminals but also on tanycytes.


Role of adrenoreactive structures of the amygdaloid complex in the regulation of blood coagulation. The stimulation of alpha-adrenoreactive structures of the amygdaloid complex, both in isolation and against the background of disengaged beta-adrenoreactive structures, was carried in experiments on male cats in chronic experimental conditions through an implanted chemotrode. It was shown that the alpha-adrenoreactive structures of the amygdaloid complex exert an influence mainly on blood coagulation phases I-II. Blood coagulation phase III changes indirectly through the shortening of phases I-II. The stimulation of beta-adrenoreactive structures of the amygdaloid complex induces the elongation of blood coagulation phases I-III over the duration of the entire experiment. The stimulation of these structures in conditions of the disengagement of the alpha-adrenoreactive structures of the amygdala leads to insignificant changes in phases I-II, after which a hypercoagulation effect is observed. Blood coagulation phase III in these conditions reflects a marked hypocoagulation effect. The data obtained suggest a modulating role of the adrenoreactive structures of the amygdaloid complex in the regulation of the processes of blood coagulation.


Ontogeny and distribution of GABAA receptors in rat brainstem and rostral brain regions. Previous studies from our laboratory and others have shown that there are major age-related differences in brainstem neuronal function. Since GABAA receptors are major targets for GABA-mediated inhibitory modulation and play a key role in regulating cardiorespiratory function, especially during O2 deprivation, we examined differences in GABAA receptor density and distribution during postnatal development. Using quantitative receptor autoradiography, the present study was performed to examine the postnatal expression of GABAA receptors in the rat brainstem and rostral brain areas at five ages, i.e. postnatal day 1 (P1), P5, P10, P21 and P120. Ten-micrometer brain sections at different brain levels were labelled with [3H]muscimol in Tris-citrate buffer. We found that (i) GABAA receptors appeared very early in almost all the brainstem as well as rostral areas; (ii) at P1, the brainstem had a higher GABAA receptor binding density than rostral areas and its density peaked at P5 or P10; and (iii) receptor densities of the cerebellum and rostral brain areas such as cortex, thalamus and dentate gyrus increased with age, especially between P10 and P21, but most other subcortical areas like caudate-putamen and hippocampal CA1 area did not increase remarkably after birth. We conclude that: (i) GABAA receptors exist in most brain areas at birth; (ii) there are several patterns of postnatal development of GABAA receptors in the CNS with dramatic differences between the brainstem and cortex; (iii) brainstem functions rely more on GABAA receptors in early postnatal life than at more mature stages. We speculate that GABAA receptors develop earlier in phylogenetically older structures (such as brainstem) than in newer brain regions (such as cortex).


Immunocytochemical characterization of afferents to estrogen receptor-containing neurons in the medial preoptic area of the rat. Double-label immunocytochemistry has been employed to elucidate the chemical nature of the afferent neuronal projections to the estrogen receptor-containing neurons located in the medial preoptic area of the rat brain. To ensure a clear separation of the immunolabelled afferent profiles from the estrogen receptors, the former were visualized first and the diaminobenzidine reaction product was silver-gold intensified. Using a monoclonal antibody raised against purified human estrogen receptors, we observed an intense nuclear immunoreactivity in Vibratome, semithin and ultrathin sections. Neuropeptide-Y, serotonin-, phenylethanolamine N-methyltransferase- and adrenocorticotrophin-immunoreactive axons and varicosities were observed in close apposition to the estrogen receptor-positive cells. At the ultrastructural level, neuropeptide-Y-immunoreactive boutons were seen in synaptic contact with cells showing estrogen receptor immunoreactivity in their nucleus. These results indicate that neurons located in the medial preoptic area, one of the principal sites for the control of female reproductive function, may be influenced by both estrogen and neurotransmitters/neuropeptides via, respectively, nuclear receptors and synaptic contacts.


The regional, cellular and subcellular localization of GABAA/benzodiazepine receptors in the substantia nigra of the rat. The regional, cellular and subcellular distribution of GABAA/benzodiazepine receptors was investigated by light and electron microscopy in the rat substantia nigra. The regional distribution and density of GABAA/benzodiazepine receptor subtypes (Type I and II) was studied using quantitative receptor autoradiography following in vitro labelling of cryostat sections with tritiated ligands. This was followed by a detailed study of the cellular and subcellular distribution and localization of GABAA/benzodiazepine receptors by light and electron microscopy using immunohistochemical techniques with a monoclonal antibody (bd-17) to the beta 2,3 subunits of the GABAA/benzodiazepine receptor complex. Finally, in situ hybridization histochemistry using 35S-labelled oligonucleotide probes was used to demonstrate the cellular distribution of mRNA for the alpha 1 and alpha 2 GABAA receptor subunits in the substantia nigra. The results of the autoradiographic and immunohistochemical studies showed a close correspondence in the regional distribution of GABAA/benzodiazepine receptors in the substantia nigra. A moderate-to-high density of receptors was present throughout the full extent of the substantia nigra pars reticulata with a very low density of receptors in the substantia nigra pars compacta. Quantitative autoradiographic studies showed that: (i) the pars reticulata contained mainly central Type I receptors; (ii) the highest density of receptors was present in the caudal pars reticulata (200 +/- 38 fmol/mg) with successively lower densities of receptors in the middle (176 +/- 31 fmol/mg) and rostral (150 +/- 26 fmol/mg) levels of the pars reticulata; and (iii) the density of receptors in the pars reticulata was reduced by 34% following 6-hydroxydopamine-induced degeneration of dopaminergic pars compacta neurons. At the cellular level, GABAA/benzodiazepine receptor immunoreactivity was localized in a punctate fashion on dendrites and neuronal cell bodies in the pars reticulata. At the subcellular level, GABAA/benzodiazepine receptor immunoreactivity was associated with the pre- and postsynaptic membranes of axodendritic synaptic complexes along the length of small-to-large sized smooth dendrites in the pars reticulata. Two types of immunoreactive axodendritic synaptic complexes were identified: most (about 80%) immunopositive synapses showed equal staining of the pre- and postsynaptic membranes and were associated with small (less than 1.0 micron) axon terminals containing few mitochondria and small, round-to-pleomorphic vesicles in synaptic contact with small, peripheral dendrites; less frequently (about 20%) immunopositive synapses showed a marked immunoreactive thickening of the postsynaptic membrane and were associated with large (greater than 1.0 micron) axon terminals containing numerous mitochondria and mainly pleomorphic vesicles in synaptic contact with large mainstem dendrites.(ABSTRACT TRUNCATED AT 400 WORDS)


Involvement of Ca2+ uptake by a reticulum-like store in the control of transmitter release. At an identified neuro-neuronal synapse of Aplysia, 2,5-diterbutyl 1,4-benzohydroquinone, a selective blocker of the reticulum Ca2+ pump, was found to potentiate evoked quantal release of acetylcholine through an increased accumulation of Ca2+ in the presynaptic neuron during depolarization without any accompanying changes in the presynaptic Ca2+ current. We conclude that a rapid Ca2+ buffering system, similar to that associated with the endoplasmic reticulum, must be present in the nerve terminal and play a role in the control of Ca2+ which reaches the release system.


Evidence that ATP released from the postsynaptic site by noradrenaline, is involved in mechanical responses of guinea-pig vas deferens: cascade transmission. The release of endogenous ATP and [3H]noradrenaline, and the mechanical response of the guinea-pig vas deferens to field stimulation of its motor nerves were examined using a perfusion system. The release of ATP at rest was 0.83 +/- 0.13 pmol/g per min, and ATP released by field stimulation (8 Hz, 480 shocks) was 5.47 +/- 1.23 pmol/g. The evoked release was completely inhibited when Ca2+ was removed and 1 mM EGTA was added, or by 1 microM tetrodotoxin. The release of ATP and [3H]noradrenaline in response to field stimulation was constant with an S2/S1 ratio of 1.10 +/- 0.11 for ATP and 0.92 +/- 0.03 for [3H]noradrenaline, respectively (where S1 and S2 are stimulation periods). Prazosin (1 microM), a potent alpha 1-adrenoceptor antagonist, significantly reduced the stimulation-evoked release of ATP by 75% and significantly reduced both mechanical twitch and tonic responses, but enhanced the release of [3H]noradrenaline. This finding indicates that there is an alpha 1-adrenoceptor-mediated release of endogenous ATP. However, the prazosin-insensitive portion of ATP release (25%) is considered to be of presynaptic origin. The stimulation of alpha 1-adrenoceptors by 1-noradrenaline or methoxamine in concentrations ranging from 10 to 100 microM resulted in a concentration-dependent release of ATP and a biphasic contraction of the vas deferens: a twitch response was followed by a tonic contraction. Prazosin (1 microM) completely prevented the effect of 1-noradrenaline or methoxamine on both ATP release and mechanical response. When Ca2+ was omitted and EGTA (1 mM) was added, 1-noradrenaline was still able to release ATP but failed to produce contraction. Nifedipine, a Ca-channel and ATP receptor antagonist, reduced the twitch contraction and enhanced the release of ATP from muscle in response to noradrenaline administration. This finding indicates that the release of ATP from the muscle is not linked to mechanical contraction. When the vas deferens was made deficient in noradrenaline by 6-hydroxydopamine pretreatment (100 + 250 mg/kg, i.p.), electrical field stimulation failed to release [3H]noradrenaline and ATP. Under these conditions, exogenous 1-noradrenaline was much more effective in releasing ATP from the smooth muscle, and producing twitch responses, followed by a tonic contraction. After reserpine pretreatment (2 x 5 mg/kg, i.p.), the field stimulation-evoked release of ATP and both phases of contraction were markedly reduced.(ABSTRACT TRUNCATED AT 400 WORDS)


Lead ions close steady-state sodium channels in Helix neurons. Extracellularly applied Pb2+ (1-150 microM) induced an outward current (IPb) in intracellularly perfused snail neurons. The current-voltage relationship of the Pb(2+)-induced current was linear over the potential range of -100 to -40 mV with negative slope conductance. The Pb-induced current was strongly dependent on the Na+ gradient. The IPb in intra- or extracellular K+- and Cl(-)-free or -rich solutions was almost the same as in control external and internal salines. The negative slope of the I-V curve and the decreased conductivity during Pb2+ application suggested that IPb is owing to the blocking of the resting Na conductance. Data obtained from single-channel measurements also supported this conclusion. Patch-clamp data showed that the steady-state Na channel has a conductance of 14 pS and both closed and open time-distributions displayed single exponential character.


Electrophysiological localization of distinct calcium potentials at selective somatodendritic sites in the substantia nigra. The dendrites of dopaminergic neurons in the substantia nigra play a pivotal role in the neurochemical homeostasis of the nucleus. It is conceivable therefore that the cell body and dendrites of these nigral neurons possess distinct and independent electro-responsive features. By means of differential polarization through applied electric fields, the cell body and dendrites have been activated in effective isolation during intracellular recordings from pars compacta neurons in the substantia nigra in vitro. In one class of neurons, which discharge in a "phasic" fashion and are located in the rostral substantia nigra, the dendrites are shown to be the origin of classic low-threshold and high-threshold type calcium potentials: indeed the high-threshold conductance appears to be exclusively dendritic. By contrast, in a second, more caudally located cell type, which discharges rhythmically, a high-threshold calcium spike is located principally in the cell body. The differential localization of these calcium conductances in sub-populations of neurons is likely to determine the functions for the calcium responses in each type of neuron, and moreover highlight the dendrites as dynamic and selective components in the physiology of the substantia nigra. The presence, for example, of the high-threshold calcium conductance in the dendrites of only one class of neuron suggests that this sub-population plays a prominent role in non-classical phenomena of dendritic release of a variety of chemical mediators.


Age-related changes in kappa opioid receptors in the guinea-pig brain: a quantitative autoradiographic study. Investigation into the effect of aging on kappa opioid receptors in the brains of guinea-pigs was carried out in animals aged one, six, 24 and 36 months. Quantitative autoradiography was used to monitor the concentration of kappa receptors in various anatomic regions at five rostrocaudal levels in each age-group. Areas of high binding were found in the deep layers (laminae V, VI) of the neocortex and in the internal band of the periallocortical, dorsal agranular insular cortex. Among non-cortical areas examined, the nucleus accumbens and the substantia nigra possessed kappa binding levels equal to those seen in the deep neocortical layers. In all cases where an age-related change in the level of kappa receptors was detected, the direction of the change was one of decreased binding with advancing age. Statistical analysis of the binding data revealed that the one-month-old animal possessed the highest levels of kappa binding among all age groups examined. The vast majority of age-related changes in kappa binding levels occurred in laminae V and VI of neocortical regions. The per cent decreases (18-42%), as well as their age of onset (six to 36 months) varied in different anatomical regions. Possible mechanisms to explain the age-related decreases in kappa opioid binding are presented. The majority of the age-related decreases in kappa opioid binding are found in areas of the neocortex which are characterized by their motor, sensory and associative functions. It is within these three areas of function that diminutions in performance are most apparent in senescence.


Lidocaine unmasks silent demyelinative lesions in multiple sclerosis. Blockage of a small number of sodium channels may prevent impulse conduction in some demyelinated segments of nerve fibers with low safety factors, thereby unmasking subclinical demyelinative lesions. On the basis of this hypothesis, lidocaine, a sodium channel blocker, was administered intravenously to 28 MS patients and to 19 normal subjects and seven patients with nondemyelinating diseases. As predicted, lidocaine (mean plasma level, 2.7 micrograms/ml) elicited reversible subclinical symptoms in 23 of the MS patients, but it had not effect on the control subjects. We made a quantitative study of the visual functions (visual acuity, color vision, visual evoked potential [VEP]) that were impaired in 15 MS patients. Of the 23 affected eyes, nine showed normal VEPs, indicative of the test's sensitivity to focal lesions. This test should be useful in the diagnosis of MS and in the evaluation of the subclinical activity of MS as well.


[Phyllodes tumor of the breast].

[Phyllodes tumor of the breast]. The diagnosis of benign, malignant or borderline phylloides tumor of the breast is based on a combination of clinical and histological features but the biological behavior of this neoplasm is not often predictable: the most important indicators of malignant behavior are underscored. Only a few patients with malignant or borderline lesions develop distant metastasis; local recurrences do not appear to effect survival: as a consequence, wide resection should to be primary treatment and axillary dissection is not worthwhile.


[Current etiopathogenic guides in pulmonary embolism]. Pulmonary embolism is still a dangerous postoperative complication in spite of antithrombotic prophylaxis. The paper examines the etiopathogenetic stages of the disease and stresses the relevance of Wircov's triad today, even in the light of recent acquisitions which highlight the role of endothelium as a modulator of the fibrinolytic process.


[Epidemiology of female ano-genital condylomata acuminata. In relation to the presence of specific types of the human papillomavirus]. The presence of 7 human papillomavirus (HPV) types in genital condylomata acuminata (GCA) from 94 otherwise healthy women was detected by in situ hybridization, employing 3 different DNA probe cocktails (6/11, 16/18 and 31/35/51). HPV+ and HPV- GCA did not differ significantly as to the multiplicity and site of lesions, nor the prevalence of younger age, previous pregnancies or abortions, oral contraception, concurrent vaginal infection, aspecific PAP-test abnormalities and cutaneous hypo-anergy. Of note is that 13/18 HPV+ GCA (72.2%) lodged HPV types (16, 18, 31, 35, 51) which are more commonly related to dysplastic and neoplastic lesions of the female genital tract.


Stimulation of erythropoietin in renal insufficiency by hypobaric hypoxia. Patients with renal anaemia show inadequate levels of immunoreactive erythropoietin (Epo) related to the degree of anaemia. The purpose of our study is to compare the degree of stimulation of Epo by means of hypobaric hypoxia in normal controls and patients with renal anaemia. Baseline Epo concentrations were found to be 11.1 +/- 2.0 U/l in 10 healthy volunteers and 11.4 +/- 4.6 U/l in six patients with renal anaemia. After exposure to hypobaric hypoxia equivalent to 4560 m above sea level for a duration of 3.5 h, we observed a significant increase in serum Epo in healthy volunteers to 22.8 +/- 9.1 U/l (P < 0.005), while there was no increase in patients with renal anaemia: 12.3 +/- 5.2 U/l (P < 0.2). Our results show that in patients with renal anaemia serum Epo concentrations are comparable to those of normal controls, but inadequate in view of the concomitant degree of anaemia. Stimulation by acute hypobaric hypoxia was not possible in patients with renal insufficiency as opposed to normal controls. From these data it can be concluded that either Epo production is working at maximum capacity under baseline conditions, or an additional hybobaric stimulus is not able to influence a disturbed set point of the oxygen sensor regulating Epo synthesis.


Reconciliation between urea kinetics and direct dialysis quantification. Previous studies comparing urea kinetic model (UKM) and direct dialysate quantification technique (DDQ) found statistically different results as far as the urea distribution volume (V) and protein catabolic rate (PCR) are concerned. In these studies, however, the true values for both the dialyser urea clearance (K) and urea concentration (C) were not used. The aim of this study was to compare UKM and DDQ using for both methods a variable-volume single-pool (VVSP) model as well as plasma water C and effective K. The study was performed during paired filtration dialysis (PFD) sessions because this technique allows bloodless measuring of K. Twenty dialysis patients were studied during a single PFD session. Dialysate and ultrafiltrate C and urea mass transfer rate were measured every 15 min to compute averaged K and total urea removal. Blood samples were obtained as for a three-point UKM, and an iterative technique was used for both methods. The results (means +/- SD) obtained with UKM were as follows: K = 176 +/- 23 ml/min; V = 29986 +/- 7620 ml, PCR = 65 +/- 15 g/day, Kt/V = 1.04 +/- 0.17. These results were not statistically different from those obtained using DDQ. In conclusion, when methodological errors are avoided, DDQ and UKM provide very similar results. This study shows also that PFD is very useful for studying solute kinetics during dialysis.


Ventricular late potentials in haemodialysis patients and the risk of sudden death. Cardiovascular diseases account for approximately 50% of deaths in patients on chronic haemodialysis. Therefore we prospectively studied 54 consecutive patients on dialysis for the presence or absence of ventricular late potentials (LP). LP, i.e. low-amplitude potentials in the terminal part of the QRS complex, have been shown to be highly indicative of life-threatening arrhythmias and sudden death. The results were correlated with echocardiographic studies and the clinical outcome during a follow-up period of 18 months. Fifty patients were suitable for evaluation (29 males, 21 females; mean age 55 years; mean time on dialysis 32 months; coronary artery disease present in 5) Our analysis revealed LP in seven of 50 patients only. Left ventricular hypertrophy, i.e. mean wall diameter > 12 mm, was present in 78%, a compromised left ventricular function, i.e. shortening fraction < 28%, was found in 28% of the patients. With respect to echocardiographic parameters, patients with and without LP were similar. During follow-up, sudden cardiac death was observed in three of 11 patients deceased. LP were detectable in one of the three only. From the remaining six patients with LP, four are still alive, and two patients died due to atherosclerosis and pulmonary embolism. Our data underline the crucial role of sudden cardiac death in dialysis patients. Ventricular late potentials, however, are of no prognostic relevance with respect to identification of dialysis patients at risk of sudden death.


Does the arteriovenous fistula in chronic haemodialysis patients stimulate endothelin-1 release? Plasma endothelin-1 (ET-1)-like immunoreactivity was measured by radioimmune assay in predialysis plasma samples from 16 chronic haemodialysis patients (7 dialysing through arteriovenous (AV) fistulae and 9 using central venous cannulae for access), from 10 patients with functioning renal transplants (5 with AV fistulae and 5 without), and from 6 healthy subjects as controls. Among dialysis patients, ET-1 was greater in those with AV fistulae than in those using cannulae for dialysis (median (range), 5.5 (3.1) pM versus 3.7 (2.0) pM, P = 0.02), and in all haemodialysis patients ET-1 values were substantially greater than in normal controls (3.9 (3.2) pM versus 0.5 (0.1) pM; P = 0.001). In patients with functioning AV fistulae, ET-1 concentrations obtained directly from the AV anastomosis of the fistula (4.4 (3.0) pM) were less than those taken simultaneously from the contralateral arm (5.5 (3.1) pM; P = 0.04), while samples drawn from the venous side of the fistula were intermediate (4.6 (3.4) pM). In renal transplant recipients, ET-1 values did not differ significantly from those in control subjects (0.7 (1.9) pM versus 0.5 (0.1) pM, n.s.), but in these patients there was a significant difference between peripheral venous ET-1 in transplant patients with and without AV fistulae (0.8 (1.9) pM versus 0.6 (1.1) pM respectively, P = 0.04). The results suggest that the increased blood flow rate through the arterialized venous circulation in the fistula arm stimulates increased ET-1 release in these patients, and that this accounts, at least in part, for the increased ET-1 found in the patients with functioning AV fistulae.


The course of autonomic neural function in chronic uraemic patients during haemodialysis treatment. Autonomic function was followed in 19 patients with uraemia on chronic haemodialysis treatment over a period of 18 months. A smaller group of 12 patients were studied over 56 months. The battery of cardiovascular reflex tests included R-R interval variation test, deep breathing, Valsalva manoeuvre, heart rate, and blood pressure responses to standing and sustained handgrip. Two indices of autonomic function were measured: the autonomic score, and the confidence level on Bayesian analysis. There was great variability in the course of autonomic function over the period studied, with improvement occurring in some subjects and deterioration in others. In addition some patients did not develop any abnormality. Among those patients with uraemia and normal autonomic function at the start of the study, a deterioration occurred in 33-36% in the 18-month follow-up but in 62.5% in the 56-month follow-up. As a group there was no significant change in autonomic function during follow-up, although a clear trend to deterioration was found despite chronic haemodialysis treatment.


Apo AIV in plasma and dialysate fluid of CAPD patients: comparison with other apolipoproteins. Plasma lipids and apolipoproteins were determined in 18 patients with chronic renal failure on haemodialysis (HD), 18 patients on continuous ambulatory peritoneal dialysis (CAPD), and 18 healthy controls. Significant differences were observed between the two dialysis procedures, CAPD patients showed elevated plasma cholesterol, apo AI and apoB. No significant difference in plasma apo AIV concentration was observed between the two dialysis groups. Measurement of apolipoproteins in the dialysate fluid of five patients on CAPD showed losses of all apolipoproteins (AI, AII, AIV, B, CII, CIII and E). Although daily losses of apo AI and apo AIV were similar (255 and 221 mg/day respectively), the peritoneal clearance of apo AIV was threefold that of apo AI and 12-fold that of apo B. In view of the inverse correlation between peritoneal clearance and the molecular mass of proteins, about 13% of total plasma apo AIV was lost daily as lipoprotein-free form.


Investigation and treatment of poor drains of dialysate fluid associated with anterior abdominal wall leaks in patients on chronic ambulatory peritoneal dialysis. Reduced dialysate fluid volume and genital and abdominal-wall oedema occurring many months after initiation of continuous ambulatory peritoneal dialysis (CAPD) has been investigated in 20 patients using computed tomographic peritoneography. Leaks into the anterior abdominal wall at the site of insertion of the Tenckhoff catheter have been demonstrated in a series of 14 patients. Nocturnal peritoneal dialysis alone led to resolution of leaks in four of the nine patients who underwent this mode of treatment. Four of the failures plus a further four patients successfully underwent either resuture of the peritoneum or replacement of the catheter. A policy for management of proven anterior abdominal-wall leaks in CAPD patients is described, consisting of nocturnal peritoneal dialysis for 2 weeks followed by surgical intervention if the former is unsuccessful.


Peritoneography and peritoneal computerized tomography: a new approach to non-infectious complications of CAPD. The introduction of the contrastographic medium (PG) eventually combined with CT scan (PCT) has been used in the study of non-infectious abdominal complications of patients on CAPD. In 27 patients on CAPD from 0 to 98 months we infused, through the peritoneal catheter, 100-200 ml of iopamidol and 500-2000 ml of peritoneal dialysis solution, effecting radiograms in different projections (27 cases), with contiguous axial scannings of 10 mm (8 cases). The information obtained was useful with regard to the therapeutic choices; it clarified the extent, the width, and the anatomical relations of hernias (7/7); the leakage site at the introduction point of the catheter (2/5), and site of surgical treatment (2/5); an inguinal hernia (1/4) and the previousness of the peritoneovaginal duct (3/4) in cases of the genital oedema; a displaced non-opaque catheter (1/4); obstruction of the terminal hole (2/4); wrapping of the omentum in a catheter malfunction (1/4); the presence of scar tissue and pathological recesses in the reduction of ultrafiltration (2/3); and the extension of secondary scar tissue after surgery and before CAPD was started. There were no infective complications or allergic reactions during the research. In conclusion, after reparative surgical intervention, PG and PCT are simple, convenient investigations, with significant diagnostic usefulness, before the introduction of the catheter and/or in cases of complications during CAPD.


Post-renal transplant diabetes mellitus--a retrospective study. The prevalence of post-transplant diabetes mellitus in 222 consecutive live related renal allograft recipients over a 3-year period was found to be 11.7%. Most of them (20 of 26) developed diabetes mellitus within the first 4 months of transplantation. Post-transplant diabetic patients were older, and had a significantly greater incidence of avascular necrosis of bone. An assessment of risk factors showed that abnormal postprandial blood sugar pretransplant was a significant predictor for development of post-transplant diabetes, whereas cumulative oral steroid dose, weight gain after transplant, type of immunosuppression employed, and graft function were not important. We conclude that post-transplant diabetes mellitus frequently develops in patients with a predisposition by virtue of older age and pretransplant postprandial hyperglycaemia. While steroids are important in the pathogenesis, there was no demonstrable dose-response relationship; post-transplant diabetic patients may be a group with a greater propensity to steroid-induced complications.


Hypertension and renal impairment as complications of acute porphyria. Chronic hypertension with renal failure is the most common cause of death in a large family (10 children, 40 grandchildren, 109 great-grandchildren) with acute porphyria. A prospective study of 26 porphyric (19 latent) and 26 nonporphyric subjects shows a significant difference between mean systolic (141 versus 123 mmHg, P < 0.05) and diastolic (88 versus 74 mmHg, P < 0.05) blood pressures and plasma creatinines (geometric mean 99 versus 79 mmol/l, P < 0.02). Five of the 19 porphyric grandchildren have died of the complications of chronic hypertension, with renal failure in three. When the results of the retrospective and prospective studies in these 19 subjects are combined, 10 of the 16 tested (62%) had hypertension and seven of the 14 tested (50%) had renal impairment. Neither hypertension nor renal failure are known to affect the 21 grandchildren who were either not porphyric or of unknown status. This family provides a unique opportunity to study these common but little reported sequelae of acute porphyria. These complications affect subjects with latent porphyria as well as those who have experienced clinical attacks.


Effects of angiotensin II on renal sodium handling and diluting capacity in man pretreated with high-salt diet and enalapril. The antinatriuretic effect of angiotensin II (Ang II) is generally attributed to a decreased glomerular filtration rate (GFR) and an increased proximal tubular sodium reabsorption. We studied this by infusion of increasing amounts (1, 4, and 8 pmol/kg per min) of Ang II in seven water-loaded volunteers who were pretreated with enalapril and a high-salt diet. While mean arterial pressure increased from 92 +/- 3 mmHg to respectively 98 +/- 3, 110 +/- 2, and 116 +/- 2 mmHg, sodium excretion fell from 331 +/- 40 to 135 +/- 23, 65 +/- 17, and 63 +/- 22 mumol/min, and GFR from 138 +/- 9 to 128 +/- 6, 111 +/- 6, and 104 +/- 8 ml/min (P < 0.05 for each variable). At 1 pmol/kg per min, Ang II decreased maximal urine flow and the fractional excretions of lithium and uric acid. Urine sodium concentration decreased, whereas minimal urine osmolality remained unchanged. At 4 pmol/kg per min, these effects were more pronounced. Moreover, minimal urine osmolality increased from 58 +/- 4 to 72 +/- 8 mosm/kg, but sodium concentration decreased further. The step to 8 pmol/kg per min did not decrease sodium, lithium, or uric acid excretion further, but induced a further increase in minimal urine osmolality to 99 +/- 16 mosm/kg. These data suggest that the antinatriuretic effect of modestly hypertensive dosages of Ang II is not only due to a decrease in GFR and an increase in proximal sodium reabsorption, but also involves a rise in fractional reabsorption in a distal nephron segment. In addition Ang II decreases renal diluting capacity.(ABSTRACT TRUNCATED AT 250 WORDS)


Human mesangial cells synthesize interleukin 1 alpha but not interleukin 1 beta, interleukin 1 receptor antagonist, or tumour necrosis factor. There is controversy over whether mesangial cells synthesize and release IL-1 and TNF, and many of the positive experiments were performed before specific reagents and molecular probes were available. Consequently we have stimulated human mesangial cells using protocols known to stimulate the synthesis of other cytokines. No mRNA for IL-1 beta or TNF could be detected in quiescent or proliferating mesangial cells irrespective of whether they had been exposed to cytokines or not. In contrast mRNA for IL-1 alpha was detected in cells stimulated with IL-1 beta 10 ng/ml or with TNF 500 ng/ml; IL-1 alpha was also detected in cell lysates from stimulated mesangial cells. We could not detect mRNA for IL-1 receptor antagonist in any of the cell preparations. These results suggest that mesangial cells are unlikely to be a major source of IL-1 beta or TNF.


Generation of microglial cell lines by transfection with simian virus 40 large T gene. Microglial cells, which were isolated from a primary culture of neonatal rat brain, were transfected with temperature-sensitive simian virus 40 (SV40) large T gene by the calcium phosphate precipitation method. Four weeks after transfection, several colonies were generated, and cloned cells were characterized. One of the cloned cells (RBM129) proliferated actively at 37 degrees C and the dividing rate was significantly decreased at 40.5 degrees C. The expression of large T antigen was detected by western blotting in cells incubated at both 37 degrees C and 40.5 degrees C. The cell line showed high activity of non-specific esterase, isolectin B4 binding and phagocytosis. Also the cells were stained by ED 1 monoclonal antibody. These results indicate that these cells were derived from rat brain microglia, and immortalized by large T gene.


Detection of JC virus in the brains of aged patients without progressive multifocal leukoencephalopathy by the polymerase chain reaction and Southern hybridization analysis. Ninety-one brain tissue sections taken at autopsy from 33 elderly patients (63-100 years old) without progressive multifocal leukoencephalopathy were examined for the presence of JC virus DNA by the polymerase chain reaction and Southern hybridization analysis after DNA extraction. JC virus DNA was detected in 15 sections from 10 patients. These results suggest that JC virus is frequently present in the brains of aged patients.


Dibutyryl cyclic AMP has epileptogenic potential in the hippocampus of freely behaving rats: a combined EEG-intracerebral microdialysis study. The effects of dibutyryl cyclic AMP were studied with the combined EEG-intracerebral microdialysis technique in the hippocampus of freely behaving rats. It was found that intrahippocampal microdialysis with this drug produced epileptiform EEG events associated with limbic type behavioral seizures. The dibutyryl cyclic AMP-induced seizures developed with a long latency, and persisted for a prolonged period even after the removal of the drug from the microdialysis fluid. Similar EEG or behavioral manifestations did not occur during intrahippocampal microdialysis with artificial cerebrospinal fluid or ATP solutions. These data suggest that in the hippocampus, in vivo, the cyclic AMP second messenger system may be involved in potentially epileptogenic excitatory processes.


A novel kainate receptor in the insect nervous system. The pharmacology of excitatory amino acid receptors on an identified neurone in the insect central nervous system was investigated using single electrode recording techniques. Application of kainate, domoate and quisqualate elicited large, slow depolarizations with a rise time of approximately 4 min and recovery time of 23 min. Concentration-response curves were constructed giving an order of potency, domoate greater than quisqualate greater than kainate, and fitted curves demonstrated quisqualate to be a possible partial agonist, compared to domoate and kainate. Agonist responses were insensitive to the antagonists CNQX and picrotoxin and the vertebrate receptor-subtype selective agonists AMPA and trans-ACPD did not elicit any response, suggesting a novel type of excitatory amino acid receptor present on neurones in the insect central nervous system.


Cyclic AMP alteration of chloride transport into the choroid plexus-cerebrospinal fluid system. The permeation of 36Cl from blood into choroid plexus (CP) and cerebrospinal fluid (CSF) was studied in adult rats intraventricularly injected with either dibutyryl (db)-cAMP, theophylline with db-cAMP, or forskolin. All 3 treatments significantly enhanced the 15-min distribution (Vd) of 36Cl into CSF, by an average of 17-33%. In contrast, ouabain and acetazolamide (inhibitors of CSF production) reduced 36Cl uptake into CSF by 34% and 13%, respectively. A correlative analysis of the various treatments revealed that the volume of distribution of 36Cl in CSF varied inversely with that in the choroid plexus. This inverse relationship suggests drug effects on Cl movement across the apical (CSF-facing) membrane of CP.


Release of endogenous benzodiazepine receptor ligands (endozepines) from cultured neurons. Endozepines are naturally occurring small organic molecules, devoid of peptidic bonds and halogens, that act as allosteric modulators of the GABAA receptor through their actions at the benzodiazepine binding site. Endozepines are present in physiologically significant amounts in the brain and can act as potent positive allosteric modulators of the GABAA receptor. In this study, 3 endozepines present in cultured cerebellar granule cells were found to be released from neurons in a potassium-stimulated, calcium-dependent fashion. This release could also be mimicked by increasing concentrations of veratridine. Although endozepines were also found in cultured astrocytes, they could not be released in significant amounts by potassium depolarization. Differential release under depolarizing conditions and granule cell content of the various endozepines suggested a possible metabolic relationship between these two processes.


Melatonin binding to the anteroventral and anterodorsal thalamic nuclei in the rat. Pineal melatonin is a putative humoral coordinator of various circadian body rhythms. Rather few loci in the brain contain such a density of melatonin receptors that specific binding can be demonstrated by autoradiography. In this study we measured, using in vitro receptor autoradiography, displaceable binding of iodo-melatonin to the anteroventral and anterodorsal thalamic nuclei of Wistar rats (0.6-1.4 fmol/mg protein at 100 pM ligand concentration). These nuclei of the limbic system have direct connections with the retina and they participate in learning and memory functions.


Central nervous system neurons labelled following the injection of pseudorabies virus into the rat urinary bladder. Pseudorabies virus was injected into the wall of the urinary bladder and, following incubation times of 2, 3 and 4 days, central nervous tissue was processed immunohistochemically for the presence of virus. Longer incubation times resulted in more extensive spread of the virus. Infected neurons were initially found in the spinal cord (mainly lumbosacral) and, after longer survival times, in raphe nuclei, reticular area, pontine micturition center, locus coeruleus, red nucleus, hypothalamus, preoptic, and cortical areas. These data define a multisynaptic circuit of neurons whose ultimate output influences urinary bladder function.


The non-NMDA glutamate antagonist NBQX blocks the local hippocampal toxicity of kainic acid, but not the diffuse extrahippocampal damage. The neuronal lesion caused locally by the injection of 0.47 nmol kainic acid into the dorsal hippocampus was greatly reduced by the co-administration of 190 nmol 2,3-dihydro-6-nitro-7-sulphamoyl-benzo(F)quinoxaline (NBQX). Protection was particularly marked for the neurons present in the CA3 and dentate hilar regions which are the neurons most vulnerable to kainic acid. On the other hand, systemic administration of NBQX (3 doses of 30 mg/kg i.p.) was completely ineffective in blocking neuronal loss in the CA3 and hilar regions. Furthermore, neither hippocampal nor systemic NBQX could prevent the diffuse neuronal damage to other regions in the limbic system outside of the dorsal hippocampus.