[Histological changes in the retinal pigment epithelium and Bruch's membrane in senescence accelerated mouse]

Senescence associated changes of the retinal pigmented epithelium (RPE) and Bruch's membrane were investigated in senescence accelerated mouse (SAM), which is an aging model mouse, by light and electron microscopy. The most characteristic changes in RPE were swelling of basal infoldings, extension of intercellular space and accumulation of lipofuscin granules. In Bruch's membrane, discontinuation of elastic layer and abnormal increase of fine fibrils in the outer collagenous layer were observed. The aging changes in SAM were severer in the posterior retina than in the peripheral one. Moreover, these changes were seen younger age than in those of the normal BALB/c mouse.

Kinetic analysis of the GABAB-mediated inhibition of the high-threshold Ca2+ current in cultured rat sensory neurones

1. The action of baclofen on the voltage-gated Ca2+ current (ICa) was studied, using cultured neurones of the newborn rat dorsal root ganglia (DRG). Two major categories of ICa were identified: a small transient current activated positive to -60 mV (low voltage-activated ICa) and a large and slowly inactivating current activated positive to -30 mV (high voltage-activated ICa). 2. Baclofen reversibly blocked the high voltage-activated ICa and slowed the activation phase of the current in a concentration-dependent manner (0.5-50 microM). The half-maximal effective concentration was about 1.5 microM as measured by a peak of ICa. On the contrary, a high concentration of baclofen (100 microM) had no detectable effect on the low voltage-activated ICa. 3. The baclofen-sensitive component of the high voltage-activated ICa was largely inactivated by a depolarized holding potential (Vh) of -40 mV, whereas the baclofen-resistant component was not affected by a change in Vh ranging from -110 to -30 mV. 4. The high voltage-activated ICa had two components of current decay: an inactivating component and a quasi-sustained component, with time constants about 420 and 1220 ms, respectively. The time constant of decay for the inactivating component was not affected by replacement of external Ca2+ with Ba2+, whereas that for the quasi-sustained component was markedly prolonged, suggesting that the decay of this component may be due to Ca(2+)-induced block rather than voltage-dependent inactivation. A high concentration of baclofen (50 microM) selectively blocked the inactivating component. 5. The decay phase of the baclofen-sensitive component of the high voltage-activated ICa was best fitted by a sum of two exponentials, with 29.2 and 481 ms for the fast and slow components, respectively. The time constants of the two components were not affected by an increase in the concentration of baclofen, whereas the amplitudes changed concentration-dependently. 6. The slowed activation of the high voltage-activated ICa by baclofen was partially reversed by a large depolarizing pre-pulse. However, such an acceleration of the current was similarly observed in the control solution. Furthermore, the actual current size increased by the pre-pulse was similar in both the control and baclofen-containing solutions. 7. These results suggest that baclofen selectively blocks the inactivating component of the high voltage-activated ICa which forms a rapid rising phase of this current, thus slowing the activation phase of the total high voltage-activated ICa.

Ontogenic development of the TTX-sensitive and TTX-insensitive Na+ channels in neurons of the rat dorsal root ganglia

Developmental changes in the sensitivity of neurons to tetrodotoxin (TTX) were studied in relation to the cell size in rat dorsal root ganglia (DRG). Na+ currents were recorded from neurons of various stages of development. Two types of Na+ channels were identified on the basis of their sensitivity to TTX. One type was insensitive to a very high concentration (0.1 mM) of TTX, while the other type was blocked by a low concentration (1 nM) of TTX. These two types of Na+ channels were observed throughout the developmental stages examined from day 17 of gestation and adulthood. Thus, both types of Na+ channels are already established at the early stage of neuronal development and appear to be retained throughout the life-span of the DRG neuron. The concentration-response relationships for the block of TTX-sensitive Na+ current by TTX did not appreciably change during development. Although two types of Na+ channels had strikingly different kinetic properties, the kinetic properties of each channel type were basically similar throughout development. The TTX-sensitive Na+ channels were mainly concentrated in cells with large cell diameters throughout developmental stages examined. These large cells appear to correspond to the 'large-light' cells. On the contrary, the TTX-insensitive Na+ channels were found in smaller diameter cells which may correspond to the 'small-dark' cells. Thus, it is concluded that there are heterogeneous categories of neurons which have Na+ channels with different physiological and pharmacological properties. Since Na+ channels play a pivotal role in the action potential generation, these heterogeneity of DRG neurons appear to be instrumental in integrating the sensory signals.

Primary culture of neurons derived from the adult mammalian brain

A method is described for the isolation and culture of neurons in the adult mammalian brain. The cell could be maintained in primary culture for more than several weeks. Whereas the neurons freshly dissociated from the adult brain did not respond to any of the neurotransmitter substances applied, the neurons regained the ability to respond to a variety of neurotransmitters when cultured. The cultured neurons of the adult mammalian brain may be an excellent model for physiological as well as pharmacological investigations of the central nervous system.

[Primary culture of mammalian brain neurons and its application to patch-clamp recording]

A method is described for the primary culture of neurons from adult mammalian brain. The primary culture consists of five processes: 1) preparation of brain slices, 2) microdissection of the discrete area, 3) enzymatic treatment of the tissue, 4) dissociation of cells by mechanical agitation of the tissue fragments, and 5) plating and feeding of dissociated cells. The cells could be maintained in culture for more than several weeks. Whereas neurons freshly dissociated from the adult brain do not respond to exogenously applied neurotransmitter substances, probably due to destruction of receptors by the enzymatic treatment, the neurons regained the ability to respond to a variety of neurotransmitters when they were cultured. Cultured neurons from adult mammalian brain are proving to be an excellent model for physiological as well as pharmacological investigations on the central nervous system.

Degradation of mitochondrial phospholipids during experimental cerebral ischemia in rats

Changes in content of brain mitochondrial phospholipids were examined in rats after 30 and 60 min of decapitation ischemia compared with controls, to explore the degradation of the mitochondrial membrane and its relation to dysfunction of mitochondria. Activities of respiratory functions and respiratory enzymes (cytochrome c oxidase; F0F1-ATPase) decreased significantly during ischemia. Considerable decreases in cardiolipin and phosphatidylinositol content were observed after 60 min, and other phospholipids showed similar but nonsignificant decreases in content. The amount of polyunsaturated fatty acids chains, such as arachidonic and docosahexaenoic acids, was reduced in each phospholipid, in some cases significantly, after 30 and 60 min of ischemia in time-dependent manners. Degradation of mitochondrial phospholipids during ischemia associated with the deterioration of mitochondrial respiratory functions suggested the significance of such changes in phospholipid content in disintegration of cellular energy metabolism during cerebral ischemia.

Significance of urinary endotoxin concentration in patients with urinary tract infection

Endotoxin is a component of the outer membrane of gram-negative rods (GNR). Since GNR are responsible for the majority of urinary tract infection (UTI), we measured the concentration of endotoxin in urine using chromogenic endotoxin-specific assay and examined its diagnostic utility in patients with suspected UTI. In all 18 urine samples with an endotoxin concentration exceeding 350 pg/ml and 2 samples with 10-350 pg/ml of endotoxin concentration, GNR were detected at a count of 10(4) cfu/ml. Negative for endotoxin were 3 samples of culture positive for gram-positive cocci (GPC), 2 samples containing various bacterial contaminants and all 37 samples with no growth on culture. Two urine samples collected 5 h after antibiotic dosage showed negative culture for GNR but a significant concentration of endotoxin. In an in vitro experiment, a residual concentration of antibiotic in urine inhibited bacterial growth, leading to a false-negative culture. These results suggest that chromogenic endotoxin assay is a reliable method for diagnosing UTI caused by GNR and detecting false-negative culture of GNR.

A simple and multi-purpose "concentration-clamp" method for rapid superfusion

A simple method for the rapid exchange of the medium used for a variety of electrophysiological experiments including patch-clamp experiments on cultured cells is described. The advantages of this method over the conventional ones are that this solution exchange system has a very simple structure and thus is inexpensive and can be easily installed in already existing experimental setups. The method involves the use of a fine double-barrelled polyethylene needle placed near the cell or other isolated preparations under recording. Electromagnetic valves are used to switch the solutions in the polyethylene tubes which enable a rapid and localized application of test solutions as well as their rapid washout. The latency of solution exchange, as measured by a change in the holding current under voltage-clamp experiments was fairly rapid (about 120 ms). Neither was the recording interrupted nor the sealing resistance affected during repeated exposure to test solutions. This method is proving to be useful, particularly for electrophysiological and pharmacological studies on immovable cells such as those in culture.

Neutrophil function in hyperosmotic NaCl is preserved by phosphoenol pyruvate

Hyperosmolarity in the urinary tract inhibits the host defense against bacterial infection. NaCl contributes most to osmolarity in the renal medulla and urine. Therefore, we studied the effect of hyperosmolar NaCl on neutrophil function. When osmolarity was increased by NaCl, polymorphonuclear leukocytes (PMNL) became defective in phagocytosis, intracellular killing of bacteria, chemotactic activity, and superoxide production. This coincided with a decrease in the intracellular adenosine triphosphate (ATP) content of PMNL. Both the inhibition of superoxide production and the reduction in ATP content did not occur at 4 degrees C. By increasing ATP content, phosphoenol pyruvic acid (PEP) protected against the decrease in superoxide production. These results suggest that leukocyte function is inhibited by high concentrations of NaCl due to the activation of the Na(+)-K+ pump. PEP, an ATP precursor, can protect PMNL against osmotic stress by raising the intracellular concentration of ATP.

Role of superoxide in renal scarring following infection by mannose-sensitive piliated bacteria

The role of superoxide in scar formation following renal infection caused by mannose-sensitive (MS) piliated strains of bacteria was studied in the experimental pyelonephritis model using female Sprague-Dawley rats. The MS piliated strain stimulated renal scarring to a significantly greater extent than either the non-piliated or MR-piliated strain. Modulation of leukocytes by administering cyclophosphamide to induce neutropenia and colchicine to inhibit leukocyte migration was effective in preventing renal scarring. Treatment with superoxide dismutase during the early stage of infection was also effective in preventing scar formation. Finally, the production of superoxide by rat leukocytes was significantly larger following stimulation by MS piliated than either the non-piliated or MR piliated strains. These observations suggest that superoxide released from leukocytes plays a critical role in the development of renal scarring following a bacterial infection, especially by MS piliated strains.

Nucleotide sequence and mutation rate of the H strain of hepatitis C virus

Patient H is an American patient who was infected with hepatitis C virus (HCV) in 1977. The patient became chronically infected and has remained so for the past 13 years. In this study, we compared the nucleotide and predicted amino acid sequences of the HCV genome obtained from plasma collected in 1977 with that collected in 1990. We find that the two HCV isolates differ at 123 of the 4923 (2.50%) nucleotides sequenced. We estimate that the mutation rate of the H strain of HCV is approximately 1.92 x 10(-3) base substitutions per genome site per year. The nucleotide changes were exclusively base substitutions and were unevenly distributed throughout the genome. A relatively high rate of change was observed in the region of the HCV genome that corresponds to the non-structural protein 1 gene region of flaviviruses, where 44 of 960 (4.6%) nucleotides were different. Within this region there was a 39-nucleotide domain in which 28.2% of the nucleotides differed between the two isolates. In contrast, relatively few nucleotide substitutions were observed in the 5' noncoding region, where only 2 of 276 (0.7%) nucleotides were different. Our results suggest that the mutation rate of the HCV genome is similar to that of other RNA viruses and that genes appear to be evolving at different rates within the virus genome.

[Pharmacology and physiological function of gamma-aminobutyric acid B type receptor]

Baclofen, a beta-chlorophenyl derivative of gamma-aminobutyric acid (GABA), depresses neuronal excitability in various parts of the central nervous system. The site of action for this drug had once been considered to be distinct from GABA recognition sites. In addition to the classical GABA recognition site (GABAA site), a new class of GABA receptor (GABAB site) has been characterized. GABAB sites are mainly present on nerve terminals and, when activated, result in diminished transmitter release, probably through a reduction in Ca2+ influx. Baclofen was shown to be a selective agonist for this novel GABAB recognition. Baclofen also directly hyperpolarizes the membrane of mammalian brain neurons, in addition to its presynaptic action. This postsynaptic action of baclofen was shown to result from an increase in K+ conductance when studied in hippocampal pyramidal neurons through postsynaptic GABAB receptors. Thus, the inhibitory neurotransmitter GABA activates two receptor subtypes that can be distinguished by their physiological and pharmacological properties. GABAA receptors mediate rapid alterations in the distribution of Cl- across the membrane. GABAA receptors are linked directly to an ion channel, thus contributing to the prompt inhibition of cellular excitability. On the contrary, the GABAB receptor does not contain an integral ion channel and is thus responsible for slower responses through receptor-G-protein-effector complexes. G-protein may be directly coupled to K+ or Ca2+ channels. In addition, G-protein may modulate a variety of regulatory proteins or second messengers, thus contributing to the slower alteration of cellular excitability or to the modulation of neurotransmitter release.

Preoperative oral and postoperative parenteral antibiotic prophylaxis of wound infection in total cystectomy with ileal urinary diversion

We describe an investigation of postoperative abdominal infectious complications and discuss two regimens for preoperative antibiotic bowel preparation in cases who underwent total cystectomy with ileal urinary diversion. Ten cases (28.6%) of 35 who had been operated developed abdominal infectious complications. Six showed abdominal wound infection, 2 showed intrapelvic abscess and 2 showed abdominal wound infection with intrapelvic abscess. Of the 19 strains of organisms isolated from the postoperative infections, 11 (57.9%) were anaerobic bacteria and the most commonly isolated bacteria was Bacteroides. A significantly lower incidence of postoperative infection was found in cases who had received tobramycin and vancomycin (0%) than in those who had received kanamycin alone (41.7%). These results indicate that anaerobic bacteria are the major contributors to postoperative infections following total cystectomy with ileal urinary diversion and that tobramycin-vancomycin prophylaxis greatly reduces the incidence of postoperative infections.

Inhibition of chemiluminescent response of human polymorphonuclear leukocytes by hyperosmolality comparable to renal medulla and preservation by ofloxacin

Hyperosmolality of the urine and renal medulla inhibits polymorphonuclear leukocyte (PMN) functions such as phagocytosis, intracellular killing and superoxide generation. The main factors of hyperosmolality in the urinary tract are urea and NaCl. We studied the chemiluminescent (CL) functions of PMNs in hypersomotic urea and NaCl solutions and the effects of ofloxacin, a new quinolone antimicrobial, for inhibiting the functions of PMNs subjected to hyperosmolality. When PMNs were incubated with hypersomotic urea and NaCl solutions, the CL response was significantly reduced. The reduced CL response was significantly preserved by supplementation with ofloxacin (OFLX). The CL response of PMNs may thus also be reduced in the urinary tract and OFLX may exert strong antimicrobial and preservative effects on PMN.

Point mutation, allelic loss and increased methylation of c-Ha-ras gene in human hepatocellular carcinoma

Somatic alterations of the c-Ha-ras gene were examined in 21 Japanese patients with hepatocellular carcinoma. Restriction endonuclease analysis by double digestion with MspI and HpaII revealed that DNAs from two of 21 hepatocellular carcinoma tissues were affected by nucleotide substitution at the twelfth amino acid coding sequence of the c-Ha-ras gene. DNAs from cirrhotic noncancerous liver tissue, but not leukocytes, of one of these patients possessed the mutation, whereas DNAs from noncirrhotic liver tissue and leukocytes of the other patient did not. In one of the nine patients harboring heterozygosity for c-Ha-ras-related BamHI-fragments, the loss of one allele was demonstrated as a somatic change not only in DNA from the tumor tissue but also in DNA from the cirrhotic nontumorous tissue. In two of the 19 patients comparatively examined for digestion patterns of c-Ha-ras locus with HpaII and MspI, extensive methylation was observed as a somatic modification in both DNAs from the tumor and the cirrhotic nontumorous tissues. These results thus indicate that the genetic lesions affecting the c-Ha-ras gene do occur in human hepatocellular carcinoma and probably serve as one of the multiple steps in the process of hepatic carcinogenesis.

[Right anterior caudo-cranial oblique (RACCO) view of portal branches]

The right caudocranial oblique (RACCO) view which is obtained by tilting the image intensifier 25 degrees caudally and 30 degrees to the right while the patients lie in supine position is proposed for improved depiction of the portal venous system. Transarterial portography with digital subtraction angiography was performed in the RACCO and posteroanterior (PA) views in 32 patients. Comparison of the two views revealed that the RACCO view was superior to the PA view of the left main branch in 25 patients (78%) and of the right posterior lobe branch in 24 (75%) patients. Visibility of more distal portal branches, however, did not always improve by RACCO view. RACCO view will be useful for the evaluation of portal systems of primary and secondary hepatic neoplasms as a special view following portogram in PA projection when more detailed information is necessary on proximal portal branches.

Sodium current kinetics in freshly isolated neostriatal neurones of the adult guinea pig

Neurones of the neostriatum were freshly dispersed from the adult guinea pig brain. A fast, transient inward Na+ current (INa) was analysed using the whole-cell patch-clamp technique. Upon depolarizations, INa developed with a sigmoidal time course, which was described by m3 kinetics. INa showed an activation threshold of about -60 mV, a peak current at -30 to -20 mV, and a reversal of polarity at +60 mV. The steady-state activation (m infinity) curve for INa had a slope factor of about 9 mV for a change in the rate constant by a factor of e) in the range between -50 mV and -20 mV. Conversely, the backward rate constant (beta m) decreased as the membrane was depolarized (about 31 mV for an e-fold change). The steady-state inactivation (h infinity) curve was well expressed by the Boltzmann's equation with a half-inactivation potential of -62 mV and a slope parameter of 6 mV. The time course of INa decay followed a second-order process, whereas the recovery from inactivation was described as a first-order process. The tau h curve showed a bell-shaped configuration with a maximum value at -60 mV. The forward rate constants (alpha h) decreased as the membrane was depolarized (about 17 mV for an e-fold change) in the range between -50 mV and -20 mV. The backward rate constants (beta h) increased as the membrane was depolarized (about 10 mV for an e-fold change). There was a significant overlap between m infinity and h infinity curves, suggesting a steady influx of Na+ (window current).

A comparison of the molecular structure of integrated hepatitis B virus genomes in hepatocellular carcinoma cells and hepatocytes derived from the same patient

To elucidate critical genetic elements in the development of hepatocellular carcinoma associated with hepatitis B virus DNA integration, a single integrant in hepatocellular carcinoma cells and one species of multiple integrants in hepatocytes, both obtained from the same patient, were compared structurally using molecular cloning techniques. Both hepatitis B virus integrants showed similar inverted repeat sequences consisting of two defective virus genomes. The recombination of viral DNAs seemed to be mediated by short regions of base homology near the direct repeat 1 and at other regions of the virus genomes in both integrants. The virus component in the junction with host DNAs was the cohesive end region in each identical end of the viral integrant in hepatocellular carcinoma cells and in one end of the viral integrant in hepatocytes. The structure of the integrant in hepatocellular carcinoma cells was characterized by an inverted, duplicated conformation composed not only of integrated virus genomes but also of flanking cellular sequences. It was shown to be the so-called "alpha dimer" of satellite DNA. In contrast, the flanking, nonreiterated cellular DNA in the hepatocyte-derived clone did not show discernible rearrangement. These findings suggest that a common mechanism underlies the integration of hepatitis B virus DNA so that a similar organization of inverted repeat genomes is found in hepatocellular carcinoma cells and in hepatocytes. The unstable nature of cellular DNA where DNA integration occurs may be important in generating chromosome alterations found in hepatocellular carcinoma.

Preferential association of a transcriptionally active gene with the nuclear matrix of rat fibroblasts transformed by a simian-virus-40-pBR322 recombinant plasmid

To study the relationship between the structural organization and function of the eukaryotic genome, DNA associated with nuclear matrix was analysed by using a transformed rat fibroblast cell line. The nuclear matrices were prepared from the isolated nuclei of pSV1-FR, a rat fibroblast cell line transformed by a pBR322-based recombinant plasmid containing an early gene region, which codes for large T-antigen, of simian virus 40. This transformed cell contained a single copy of the plasmid sequence integrated into the chromosomal DNA of the host cell. The early gene of this plasmid was constitutively expressed, as demonstrated by positive immunofluorescence staining of the cell for large T-antigen and by RNA-blot analysis for its specific mRNA. DNAs were extracted from whole isolated nuclei and nuclear-matrix preparations of the cells, and the relative amounts of the sequence similar to that of the plasmid were compared between these DNA preparations. By employing dot hybridization and Southern-blot analyses we found that the plasmid sequence was more enriched in the DNA extracted from the nuclear matrices than in the DNA extracted from the whole nuclei. When an albumin gene sequence that was not transcribed in this cell line was compared similarly as a control, we found no significant enrichment of this sequence in the DNA associated with the nuclear matrix. Our results strongly support the concept that a transcriptionally active gene is preferentially associated with the nuclear matrix.

Potent blocking action of chlorpromazine on two types of calcium channels in cultured neuroblastoma cells

The effects of chlorpromazine on calcium channel currents were studied in cultured mouse neuroblastoma cells (N1E-115) using the whole-cell variation of the patch-clamp technique. Two types of calcium channel currents (type I and type II) as carried by barium ions were recorded separately on the basis of their different voltage- and time-dependent kinetics. Chlorpromazine reversibly reduced the amplitude of both types of calcium channel currents. The concentration dependence of the calcium channel block indicated a one-to-one binding stoichiometry for both type I and type II currents, with an apparent dissociation constant of 15 microM in both cases. The block of calcium channels was dependent on the holding potential for both type I and type II currents, being enhanced by depolarization. This voltage dependence of the block was due to a higher affinity of chlorpromazine for the inactivated state of the calcium channels than the resting state, as demonstrated by a hyperpolarizing shift of the steady-state inactivation curve. The activation kinetics were not affected by chlorpromazine in either type I or type II current. The time course of inactivation of the type I current was not changed by chlorpromazine, whereas that of the type II current was accelerated, suggesting an involvement of an open channel block. Chlorpromazine block of type I current was independent of the level of test depolarizing pulse, whereas that of type II current was augmented with an increase in depolarization. It was concluded that chlorpromazine binds preferentially to the inactivated form of both type I and type II calcium channels, without affecting the gating kinetics of channel activation.

Differential block of sodium and calcium channels by chlorpromazine in mouse neuroblastoma cells

1. The effects of chlorpromazine on the voltage-activated sodium and type I (transient) calcium channels were studied in cultured mouse neuroblastoma cells (N1E-115) using the whole-cell patch-clamp technique. 2. Chlorpromazine (2-10 x 10(-6) M) blocked both the sodium channel current and the calcium channel current as carried by Ba2+ in a reversible and dose-dependent manner. 3. The block was not associated with any change in the time course of the activation and inactivation of the sodium and calcium channel currents. 4. The dose-response relationships for the block of these channels measured with a holding potential of -120 mV indicated a 1:1 binding stoichiometry with apparent dissociation constants of 2.5 +/- 10(-6) M and 1.5 +/- 10(-5) M for the sodium and calcium channels, respectively. 5. The block was dependent on the holding potential for both channel currents. The apparent dissociation constant for the sodium channel was decreased to 0.65 +/- 10(-6) M when the membrane was held at -80 mV. The apparent dissociation constant for the calcium channel was decreased to 3.2 +/- 10(-6) M when the membrane was held at -60 mV. 6. The steady-state inactivation curve for the sodium channel was shifted by 12.4 +/- 1.8 mV to more negative potentials by exposure to 1 x 10(-6) M-chlorpromazine. The inactivation curve for the calcium channel was also shifted by 15.4 +/- 3.2 mV to more negative potentials by exposure to 1 x 10(-5) M-chlorpromazine. These results indicate a greater affinity of chlorpromazine for the inactivated state of the channels than for the resting state. 7. Chlorpromazine caused a marked use-dependent block of the sodium channel current, as demonstrated by a cumulative increase of the block during a train of depolarizing pulses. The use-dependent block was observed even with an interpulse interval as long as 2 s. 8. On the other hand, the block of the calcium channel current did not notably accumulate during a train of depolarizing pulses even when extremely prolonged (1 s) pulses were applied at a very short interpulse interval (200 ms). 9. The marked use dependence of the sodium channel block was due to a very slow repriming of the drug-bound sodium channels from inactivation, whereas the lack of use dependence of the calcium channel block was due to a rapid repriming of the drug-bound calcium channels.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of beechwood creosote by gas chromatography-mass spectrometry and high-performance liquid chromatography

Compounds in beechwood creosote were analyzed by gas chromatography-mass spectrometry, and 22 major constituents were identified. Of these, 19 were phenolic compounds, i. e., guaiacol, phenol, two cresol isomers, four methylguaiacol (creosol) isomers, six xylenol isomers, two trimethylphenol isomers, 4-ethylguaiacol, 4-ethyl-5-methylguaiacol, and 4-propylguaiacol. The remaining three were hitherto unpredicted five-membered ring compounds, i. e., 3-methyl-2-hydroxy-2-cyclopenten-1-one, 3,5-dimethyl-2-hydroxy-2-cyclopenten-1-one, and 3-ethyl-2-hydroxy-2-cyclopenten-1-one. The relative quantities of these compounds were also compared with those obtained by high-resolution high-performance liquid chromatography. This report probably represents the first extensive analysis of beechwood creosote.

Modulation of sodium current kinetics by chlorpromazine in freshly-isolated striatal neurones of the adult guinea-pig

1. The neurones of the striatum were freshly dissociated from the adult guinea-pig brain by enzymatic and mechanical treatments. Sodium channel current kinetics in these neurones were measured using a whole cell variation of the patch-clamp technique. 2. Chlorpromazine, a neuroleptic, in micromolar concentrations reversibly reduced the amplitude of the sodium currents. Activation and inactivation time constants were not affected. The inhibition followed one-to-one binding stoichiometry. 3. The concentration-response curve shifted to the left when the holding potential was less negative. The EC50 shifted from 4.8 microM to 0.9 microM when the holding potential was changed from -120 mV to -70 mV. 4. The steady-state activation curve of the sodium current was not affected by chlorpromazine, whereas the steady-state inactivation curve was shifted in the negative direction. Consequently, the window current which is normally present at a potential range around -50 mV was decreased in the presence of chlorpromazine. 5. Successive sodium currents evoked by a train of depolarizing pulses (30 ms duration) to -10 mV showed a cumulative decrease in size during the application of chlorpromazine. However, such 'use-dependent' block was not observed when the pulse duration was reduced to 1 ms. 6. The recovery from inactivation in the presence of chlorpromazine, was expressed as a second order process. The faster component was similar to the recovery time course of the normal sodium channels. The slower component accounted for the use-dependent effect of chlorpromazine. 7. The results indicate that chlorpromazine binds to the resting sodium channels producing steady-state block at a very negative holding potential. When the membrane is depolarized, chlorpromazine binds to the inactivated form of the sodium channels with much higher affinity and stabilizes them in the inactivated state, slowing their kinetics.

Block of sodium channels by psychotropic drugs in single guinea-pig cardiac myocytes

1. Effects of imipramine and haloperidol on voltage-gated sodium channels were investigated in guinea-pig isolated ventricular myocytes by the whole-cell patch clamp technique. Some additional experiments were also performed with chlorpromazine for the purpose of comparison. 2. All test drugs in micromolar concentrations suppressed the amplitude of peak sodium current associated with step depolarization from a holding potential of -140 mV in a reversible manner. The order of potency was chlorpromazine greater than imipramine greater than haloperidol. 3. Dose-response curves obtained with a holding potential of -140 mV were best fitted by 2:1 stoichiometry in all three drugs and were shifted in the direction of lower concentrations when a holding potential of -90 mV was used. 4. The drug-induced block was not associated with any change in the time courses of sodium current activation and inactivation. 5. Steady-state sodium channel inactivation curve was shifted in the direction of more negative potentials by the drugs. 6. All three drugs also produced marked use-dependent block as demonstrated by a cumulative increase in the block during a train of depolarizing pulses. 7. The use dependence was due to a higher affinity of the drugs for the inactivated state of sodium channels than the resting state and to a very slow repriming of the drug-bound sodium channels from inactivation. 8. The steady-state and use-dependent block of voltage-gated sodium channels by psychotropic drugs may contribute to their cardiotoxic and perhaps antiarrhythmic effect.

Change in cytoplasmic free Ca2+ concentration in rabbit platelets contacting with albumin coated and uncoated polystyrene surfaces

Direct measurement of cytoplasmic free Ca2+ concentration in rabbit platelets in contact with polystyrene latexes was examined by monitoring an intracellular trapped fluorescent indicator dye, Fura 2, as a quantitative evaluation of platelet activation on material surfaces. It was found that an increase in cytoplasmic free calcium levels in platelets in contacting latexes was strongly reduced by the adsorption of albumin on the latex surfaces. Further, such an elevation of cytoplasmic free calcium levels was found to require a calcium influx from an extracellular medium across the platelet-plasma membrane.

[A case of Pickwickian syndrome treated by implantation of a cardiac permanent pacemaker]

A 41-year-old male was admitted to our hospital with congestive heart failure and bronchopneumonia. During hospitalization extreme sinus bradycardia, sinus arrest up to 6.2 seconds and high grade AV block were observed to occur simultaneously with apneic episodes of ECG monitoring. After that, a diagnosis of Pickwickian syndrome was made in this obese patient. In spite of weight reduction, change of sleep position and acetazolamide administration, obstructive sleep apnea and severe bradyarrhythmias were not improve. These severe bradyarrhythmias and ventricular tachyarrhythmias may be one cause of the not infrequent sudden deaths in patients with this Pickwickian syndrome. In addition to the tracheostomy, we propose that implantation of a cardiac permanent pacemaker should be selected for the bradyarrhythmias in association with the Pickwickian syndrome.

[Pathologic response of the regenerated retinal pigment epithelium (RPE)--affected by sodium iodate (NaIO3)]

Phagocytosis, proliferation and metaplasia to fibroblast-like cells in the regenerated retinal pigment epithelial cell (RPE) were examined after damage caused by administration of sodium iodate. The solution of sodium iodate (40 mg/kg) was given in a single intravenous injection in rats. Three days after injection, RPE showed marked necrotic damage, but in 2 weeks flat regenerated RPE with short microvilli and no basal infolding were seen on Bruch's membrane. Polystyrene particles were then injected into the subretinal space. The rats were sacrificed 6 hours to 4 days after injection of the particles. The regenerated RPE showed phagocytosis within 6 hours. After 48 hours, they showed multilayer proliferation. After 4 days RPE transformed to spindle-shaped fibroblast-like cells. However proliferation and metaplasia of RPE markedly decreased. The results showed significant decrease in the function of regenerated RPE-cells as a result of their damage.

[Pathologic response of the weak damaged retinal pigment epithelium (RPE)--affected by sodium iodate (NaIO3)]

We examined the cellular responses of the retinal pigment epithelium (RPE) damaged by sodium iodate. RPE was damaged by intravenous administration of sodium iodate, 10mg per kg body weight, in rats. This dose of the agent damaged RPE weakly. Twenty-four hours after the administration of sodium iodate, polystyrene particles were injected into the subretinal space trans-sclerally. Rats were sacrificed at 6 hours to 4 days after injection of particles. Twenty four hours after injection of sodium iodate, RPE were weakly damaged. The cell organelles were swollen and ruptured, but cell structures were not destroyed. Then particles were injected into the subretinal space, RPE did not phagocytize the particles until 24 hours after the injection of particles. After 48 hours, RPE showed proliferation. After 4 days, RPE formed thick multilayers in the subretinal space and transformed to spindle shapes, and RPE underwent metaplasia to fibroblast-like cells. However proliferation of RPE was not marked. RPE cells weakly damaged by sodium iodate showed delay in phagocytosis of the particles and decrease in proliferation and metaplasia to fibroblast-like cells.

Kinetics of chlorpromazine block of sodium channels in single guinea pig cardiac myocytes

Block of sodium current by chlorpromazine in single ventricular myocytes isolated from guinea pigs was studied using the whole cell patch clamp technique. Chlorpromazine in micromolar concentrations reduced the amplitude of peak sodium current associated with step depolarizations from a holding potential of -140 mV. Concentration-response curves obtained with a holding potential of -140 mV were best fit by a 2:1 stoichiometry, and were shifted in the direction of lower concentrations when a holding potential of -100 mV was used. In agreement with this observation, the steady-state inactivation curve was shifted to more negative potentials by chlorpromazine. The block was not associated with any change in the time course of sodium current activation or inactivation during a depolarizing step. Chlorpromazine also produced marked use-dependent block as demonstrated by a cumulative increase in the block during a train of depolarizing pulses. This use dependence was due to a higher affinity of chlorpromazine for the inactivated state of sodium channels than for the resting state and to a very slow repriming of the drug-bound sodium channels from inactivation. These blocking actions could contribute to the antiarrhythmic effects of chlorpromazine at low concentrations and to the cardiotoxic effects at high concentrations.

[Pathologic response of the retinal pigment epithelium. The effect of mucopolysaccharide in the subretinal space to phagocytosis. Part 5]

Previously we reported that retinal pigment epithelial cells (RPE) showed different phagocytotic activity according to the charge characteristics of the surface of polystyrene particles which were injected into the subretinal space of albino rats. In this study we examined whether subretinal mucopolysaccharide controls RPE phagocytosis or not, using positive or negative charged particles (3 microns in diameter). The technique of ruthenium red staining, a cationic dye, was employed with special efforts to detect the relationship between acid mucopolysaccharide and particles at the electron microscopic level. Six hours after injection of the positive charged particles, the ruthenium red staining revealed fine granular electron-dense materials, coating the surfaces of many small substances surrounding polystyrene particles which were not yet phagocytized by RPE. On the other hand, there was no staining of negative ones which were already phagocytized by RPE. At 24 hours, no staining was observed on the surface of either particles. These findings suggest that an anionic property of mucopolysaccharide in the subretinal space controls the phagocytosis of RPE.

Psychotropic drugs block voltage-gated ion channels in neuroblastoma cells

Effects of neuroleptics and tricyclic antidepressants on voltage-gated ion channels were investigated in the neuroblastoma cell line N1E-115 using the whole cell variation of patch electrode voltage-clamp techniques. Imipramine, chlorpromazine and haloperidol in micromolar concentrations blocked sodium, calcium and potassium channel currents in a reversible and concentration-dependent manner. The order of potency was chlorpromazine greater than imipramine greater than haloperidol. These direct blocking actions on neuronal ion channels might play a role in clinical effects of these drugs.

Degradation of neurofilament protein in cerebral ischemia

Degradation of neurofilament (NF) triplet proteins: NF200 (molecular weight (MW) 200,000), NF150 (MW 150,000), and NF68 (MW 68,000) as well as of other cytoskeletal proteins in the rat brain during ischemia was investigated. Sodium dodecyl sulfate-gel electrophoresis and immunoblot methods with anti-NF200 antibody were used for the study. Selective degradation of NF200 and NF150 was observed during the initial 10 to 15 minutes of ischemia. The degradation was demonstrated both in permanent ischemia caused by decapitation and in transient ischemia induced by four-vessel occlusion followed by reperfusion after 30 minutes of occlusion (modified Pulsinelli method). The degradation suggests that the activation of a protease occurs in the first 15 minutes of cerebral ischemia, which is the earliest irreversible neuronal change ever to be reported.

[Degradation of cytoskeletal proteins in cerebral ischemia]

Degradation of neurofilament (NF) triplet proteins (Mw 200,000 (NF200), Mw 150,000 (NF150), Mw 68,000 (NF68], high molecular weight microtubule-associated proteins (MAP1 and MAP2) and other cytoskeletal proteins in rat brain during ischemia was investigated by sodium dodecyl sulfate (SDS)-gel electrophoresis and immunoblot methods using anti-NF200 monoclonal antibody. Selective degradation of NF200 and NF150 was observed during the initial 10 to 15 minutes of ischemia: and the degradation of MAP1 and MAP2 during the initial 15 to 30 minutes of ischemia. These degradations suggest that the activation of a protease occurs at the very early stage of cerebral ischemia, which are the earliest irreversible neuronal changes ever to be reported. Effect of ischemia on polymerization of microtubule proteins was also investigated by turbidity assay. A rapid decrease of the ability of polymerizing microtubules was observed during the initial 5 minutes of ischemia. This loss of polymerization ability was apparently independent of the degradation of MAP1 and MAP2.

[A case of radiation myelitis following radiotherapy in lung cancer]

A case of radiation myelitis developed 1 year and 5 months after radiotherapy for lung cancer is reported. A 75-years old male was given a dose of 70 Gy to the tumor with a fraction dose of 2 Gy, 5 times per week. He developed the weakness and disturbance of sense in bilateral lower extremities, which gradually worsened in spite of a variety of treatment. Some discussions on tolerance dose, fraction dose and fraction number are made as well as technique of irradiation.

Lindane but not deltamethrin blocks a component of GABA-activated chloride channels

Effects of deltamethrin, a pyrethroid insecticide, and lindane, the gamma isomer of hexachlorocyclohexane, on the gamma-aminobutyric acid (GABA)-activated ion channels were studied using cultured neurons isolated from the newborn rat dorsal root ganglia. The neuron was voltage clamped using the whole cell patch clamp technique. Two components of inward chloride currents were generated in response to bath application of GABA. One of the components was selectively blocked by 1 x 10(-5)M lindane in a stereospecific manner, but neither component was affected by 1 x 10(-5)M deltamethrin, which drastically prolonged the voltage-activated sodium channel current. Thus, the action of lindane to stimulate the nervous system is partly because of an interaction with the GABA receptor-channel complex. The target site of deltamethrin is not the GABA receptor-channel complex but the sodium channel. The results suggest a multiplicity of the GABAA receptor-chloride channel complex.

Demonstration of pancreatic secretory trypsin inhibitor in serum-free culture medium conditioned by the human pancreatic carcinoma cell line CAPAN-1

Serum-free culture medium conditioned by an established human pancreatic adenocarcinoma cell line, CAPAN-1, contains copious amounts of immunoreactivity due to pancreatic secretory trypsin inhibitor (PSTI) as demonstrated by radioimmunoassay. The immunoreactive substance was purified from the conditioned medium to apparent homogeneity by trypsin affinity and gel filtration chromatography with an overall recovery of 40%, and its primary structure was determined by Edman degradation. The immunoreactive substance is a peptide of 56 amino acid residues with a calculated molecular weight of 6,241. Its amino acid composition, primary structure, and inhibitory effect against trypsin are indistinguishable from those of human pancreatic juice PSTI, indicating that this substance is PSTI itself. This is the first direct demonstration that tumor cells secrete PSTI in vitro. When CAPAN-1 was inoculated into a nude mouse, it produced a tumor and the tumor synthesized human PSTI in vivo, as demonstrated by the fact that the tumor extract contained 99.0 +/- 26.2 ng of human PSTI/mg of protein, while PSTI was not detected in extracts from other tissues examined. Furthermore, high levels of human PSTI (14.3 +/- 2.6 ng/ml) were detected in the serum of tumor-bearing mice but not in that of nontumor-bearing mice, suggesting that PSTI secreted from the tumor appears in the blood circulation. Taken together, these results strongly support the view that the serum levels of PSTI are elevated in cancer-bearing patients due to secretion of this peptide from tumor cells per se.

In vitro and in vivo studies on antithrombogenicity of poly(propylene oxide) segmented nylon 610 in relation to its crystalline-amorphous microstructure

In vitro and in vivo antithrombogenicity of poly(propylene oxide) segmented nylon 610 was investigated. For the in vitro simulation of thrombosis on copolymer surfaces, a modified microsphere column method evaluated the thrombosis time of the copolymer column. For the in vivo evaluation of the antithrombogenicity of copolymer surfaces, small diameter tubing, precoated with copolymer, was implanted in rabbits as an arteriovenous shunt to determine the time of patency for the copolymer tubing. In both the in vitro and in vivo tests, the copolymer having a particular size and distribution of crystalline and amorphous microphases on its surface exhibited excellent antithrombogenicity; the copolymer with a long period of approximately 12 nm and a crystallite thickness of 6.5 nm suppressed the activation process of adhering platelets to show thromboresistant property. This paper emphasizes the importance of controlling the crystalline-amorphous microstructure for the antithrombogenicity of polymer surfaces with a semicrystalline microstructure.

gamma-Aminobutyric acid (GABA) causes consistent depolarization of neurons in the guinea pig supraoptic nucleus due to an absence of GABAB recognition sites

The action of gamma-aminobutyric acid (GABA) in the supraoptic nucleus was investigated using guinea pig brain slices. GABA produced a membrane depolarization accompanied by a decrease in the input resistance. The action of GABA was concentration-dependent throughout a wide range of concentrations (10(-7)-10(-3) M). In none of the cells examined, a membrane hyperpolarization was observed. The reversal potential for the depolarization induced by GABA was about 25 mV positive to the resting membrane potential. The amplitude of the GABA-induced depolarization was increased to 1.5 X the control by reducing the external Cl- from 134.2 mM to 10.2 mM. The action of GABA was readily antagonized by relatively low concentrations of bicuculline (10(-5) M). The action of GABA in the hippocampus or in the anterior hypothalamus was markedly different from that in the supraoptic nucleus, i.e. GABA produced both depolarizing and hyperpolarizing responses in the hippocampus and consistently a hyperpolarization in the anterior hypothalamus. The depolarizing but not the hyperpolarizing response in the hippocampus was selectively blocked by picrotoxin (2 X 10(-5) M) or by bicuculline (10(-5) M). The depolarizing component was dependent on the external Cl- concentration and had a reversal potential similar to that of the depolarization induced by GABA in the supraoptic nucleus. The hyperpolarizing component was resistant to bicuculline and had a reversal potential about 30 mV negative to the resting membrane potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Potent effects of the monoclonal antibody-mitomycin C conjugate on human colon cancers

The effects of the monoclonal antibody-mitomycin C conjugate against human colon cancers were studied, in vitro and in vivo. Mitomycin C (MMC) was conjugated with the human colon cancer-specific monoclonal antibody, using a cyanogen bromide method. The effect of the conjugate and free MMC, in vitro, was measured by incubation with human colon cancer SW1116 cells. The MMC concentration of the conjugate and of free MMC needed for 50 per cent killing of target cells was 0.11 microgram/ml and 7.00 micrograms/ml, respectively. The effect of the conjugate and of free MMC, in vivo, was assayed by the growth inhibition of human colon cancer xenografted in nude mice, after intraperitoneal injections of 30 micrograms MMC/kg. Antitumor effects of the conjugate against the cancer in nude mice were significantly more potent than that of free MMC.

Contrasting properties of K+ conductances induced by baclofen and gamma-aminobutyric acid in slices of the guinea pig hippocampus

Properties of membrane K+ conductances induced by baclofen and gamma-aminobutyric acid (GABA) in the hippocampus were investigated by using guinea-pig brain slices. Baclofen hyperpolarized the membrane and decreased the input resistance of pyramidal cells through the activation of a membrane K+ conductance. GABA caused a biphasic response in pyramidal cells, consisting of hyperpolarizing and depolarizing components. Combined application of picrotoxin and bicuculline eliminated the major part of the depolarizing component of the biphasic response and produced a relatively pure hyperpolarizing response which was also mediated by an increase in K+ conductance. The K+ conductance change induced by baclofen showed prominent inward rectification. However, the K+ conductance induced by GABA did not show an obvious rectifying property. The K+ conductance activated by baclofen was strongly antagonized by a low concentration (5 x 10(-6) M) of 4-aminopyridine (4-AP). In contrast, the K+ conductance activated by GABA was insensitive to 4-AP even at a high concentration of 10(-3) M. The slow inhibitory postsynaptic potential (slow i.p.s.p.) evoked by stimulation of the mossy fibres was totally suppressed by a low concentration of baclofen (5 x 10(-6) M). Whereas GABA (10(-3) M) decreased the amplitude of the slow i.p.s.p., the reduction of the amplitude was proportional to the decrease in the amplitude of the electrotonic potentials produced by constant inward current injections. These results suggest that the hyperpolarizations induced by GABA and baclofen may be generated by K+ conductances of different kinetic and pharmacologic properties.