Induction of immediate spatiotemporal changes in thalamic networks by peripheral block of ascending cutaneous information

Peripheral sensory deprivation induces reorganization within the somatosensory cortex of adult animals. Although most studies have focused on the somatosensory cortex, changes at subcortical levels (for example the thalamus) could also play a fundamental role in sensory plasticity. To investigate this, we made chronic simultaneous recordings of large numbers of single neurons across the ventral posterior medial thalamus (VPM) in adult rats. This allowed a continuous and quantitative evaluation of the receptive fields of the same sample of single VPM neurons per animal, before and after sensory deprivation. Local anaesthesia in the face induced an immediate and reversible reorganization of a large portion of the VPM map. This differentially affected the short latency (4-6 ms) responses (SLRs) and long latency (15-25 ms) responses (LLRs) of single VPM neurons. The SLRs and LLRs normally define spatiotemporally complex receptive fields in the VPM. Here we report that 73% of single neurons whose original receptive fields included the anaesthetized zone showed immediate unmasking of SLRs in response to stimulation of adjacent cutaneous regions, and/or loss of SLRs with preservation or enhancement of LLRs in response to stimulation of regions just surrounding the anaesthetized zone. This thalamic reorganization demonstrates that peripheral sensory deprivation may induce immediate plastic changes at multiple levels of the somatosensory system. Further, its spatiotemporally complex character suggests a disruption of the normal dynamic equilibrium between multiple ascending and descending influences on the VPM.

The role of ERCP and therapeutic biliary endoscopy in laparoscopic cholecystectomy

The widespread use of laparoscopic cholecystectomy for the treatment of symptomatic gallstones has been associated with an increased use of diagnostic and therapeutic biliary endoscopy to treat common bile duct stones and postoperative complications. In 250 patients with successful laparoscopic cholecystectomy, 35 were selected for preoperative ERCP evaluation after fitting the criterion of clinical evidence with common bile duct stones (ultrasound and biochemical data). Stones were found in 16 of 35 patients (45.7%). Endoscopic sphincterotomy with stone removal was successfully carried out during the procedure. Laparoscopic cholecystectomy was performed 1 or 2 days after endoscopic sphincterotomy with good result. Only one patient without clinical evidence of common bile duct stones developed postoperative retained stone; he was successfully treated by endoscopic sphincterotomy. Three patients with postoperative bile leakage were successfully treated with endoscopic nasobiliary drainage. Diagnostic and therapeutic ERCP procedures should incorporate the newly developed method of laparoscopic cholecystectomy in order to provide a more safe and minimal invasive therapy.

Expression of gamma-aminobutyric acid immunoreactivity in reactive astrocytes after ischemia-induced injury in the adult forebrain

Transient ischemia induces an increase in glial fibrillary acidic protein (GFAP) immunoreactivity which can be detected in specific forebrain regions of the adult gerbil as early as day 2, becomes prominent by day 4-7 and persists for at least 3 months. These forebrain areas include layers 2/3 of the somatosensory and auditory cortices, the CA1 and CA4 sectors of the hippocampus, the dorsolateral region of the striatum, and the dorsolateral subregion of the medial septal nucleus. In addition, astrocytes in the ischemically lesioned areas stain with gamma aminobutyric acid (GABA) antiserum. These GABA-immunoreactive astrocytes are not found in non-damaged areas. The time-course of expression of GABA immunoreactivity is similar to that of GFAP immunoreactivity. Using a double immunofluorescent staining method, reactive astrocytes which express GABA immunoreactivity were also found to immunostain with either GFAP or vimentin. On the other hand, astrocytes were not found to be immunoreactive with antibodies to glutamic acid decarboxylase or glutamate. Our present finding demonstrates, in an in vivo model, an aberrant expression of GABA immunoreactivity by astrocytes which is not observed in non-ischemic adult animals.

Thalamic afferents of the rat barrel cortex: a light- and electron-microscopic study using Phaseolus vulgaris leucoagglutinin as an anterograde tracer

Anterograde tracers, Phaseolus vulgaris leucoagglutinin (PHA-L) and horseradish peroxidase (HRP), were used to study the thalamocortical afferents of the posteromedial barrel subfield (PMBSF) in rat primary somatosensory cortex (SI) at both light- and electron-microscopic levels. The PMBSF, also known as the barrel cortex, can be subdivided into barrel and interbarrel areas on the basis of cytoarchitectonic characteristics. Restricted injections confined to either the ventroposterior medial (VPM) or the rostral part of the posterior (Pom) nucleus allowed us to study and compare their projection patterns to the barrel cortex. We found that the interbarrel area receives inputs exclusively from the Pom, whereas the barrel area receives inputs from both the Pom and VPM. The laminar distributions of these two projections are largely segregated. After an injection of PHA-L or HRP into the VPM, labeled bouton-like swellings are found in layer VI and in layers IV through I of the barrel area, with the highest concentration in layer IV. On the other hand, after an injection of PHA-L or HRP into the Pom, labeled bouton-like swellings are distributed from upper layer V to layer I of the interbarrel area, as well as in layers V and I of the barrel area. Ultrastructural analysis showed that labeled bouton-like swellings of the VPM and the Pom pathways make synaptic contacts onto cortical neurons, and that these contacts are asymmetrical. Therefore, the VPM and the Pom projections are complementary to each other in the barrel cortex, and together they provide thalamic inputs to most layers of both the barrel and interbarrel areas. The differential patterns of terminations of the VPM and the Pom projections in the barrel cortex suggest that they may be involved in different types of cortical processing. Furthermore, our present findings may provide the anatomical basis for two parallel thalamocortical pathways, which previous physiological studies have indicated are each concerned with particular submodalities of somatic information.

Immunoreactivity for GAD and three peptides in somatosensory cortex and thalamus of the raccoon

Immunocytochemical methods were used to determine the distributions of glutamic acid decarboxylase (GAD), vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), and somatostatin (SOM) in the primary somatosensory cortex and somatosensory thalamus of adult raccoons. The cortex showed extensive immunoreactivity for GAD, revealing a large population of GABAergic neurons. GAD-labeled cells were numerous in all cortical layers, but were most concentrated in laminae II-IV. The cells were nonpyramidal and of varying morphology, typically with somata of small or medium size. GAD-immunoreactive puncta, presumably synaptic terminals, were widespread and often appeared to end on both GAD-negative and GAD-positive neurons. Immunoreactivity for the peptides was much less extensive than that for GAD, with the number of labeled neurons for VIP > CCK > SOM. Peptidergic cells were preferentially located in the upper and middle cortical layers, especially laminae II and III. The cells were nonpyramidal, often bitufted or bipolar in morphology, and small to medium in size. Their processes formed diffuse plexuses of fibers with terminal-like varicosities that occasionally surrounded nonpeptidergic neurons. The thalamus showed a clearly differentiated pattern of immunoreactivity for GAD, but little or no labeling for the three peptides. Nuclei adjoining the ventral posterior lateral (VPL)/ventral posterior medial (VPM) complex--including the reticular nucleus--contained many GAD-positive neurons and fibers. In contrast, the VPL and VPM nuclei displayed considerably less GAD immunoreactivity, somewhat surprising given the raccoon's highly developed somatosensory system. However, the ventral posterior inferior (VPI) nucleus revealed rather dense GAD labeling, perhaps related to a specialized role in sensory information processing. Thus, the primary somatosensory cortex of the raccoon showed patterns of immunoreactivity for GAD and peptides that were similar to those of other species; the somatosensory thalamus revealed a distinctive profile of GAD immunoreactivity, with labeling that was light to moderate in the VPL/VPM complex and relatively extensive in VPL.

Localization of protein-acetaldehyde adducts on cell surface of hepatocytes by flow cytometry

Acetaldehyde, a highly reactive intermediate of ethanol metabolism, has been shown to form adducts with liver proteins (e.g., a cytosolic 37 kDa protein and the microsomal cytP450IIE1) in rats fed alcohol chronically. In this study, flow cytometry was utilized to test for the presence of protein-acetaldehyde adducts (-AAs) on the surface of hepatocytes and immunotransblot was used to detect for the 37 kDa protein-AA in cytosol as was previously described. For flow cytometric analysis, rabbit anti-hemocyanin-AA IgG and fluorescein isothiocyanate-conjugated goat anti-rabbit serum IgG were used as the primary and secondary antibodies to label surface protein-AAs on hepatocytes at 0 degrees to 4 degrees C. After labeling and washing, hepatocytes were fixed with paraformaldehyde-cacodylate and analyzed with a flow cytometer. In an experiment wherein hepatocytes isolated from rats pair-fed liquid diets with and without ethanol were treated by adding both the primary and secondary IgGs, some hepatocytes from both alcohol-fed and control rats exhibited positive fluorescence but no significant difference in fluorescence intensity was noted. In another experiment, hepatocytes were isolated from rats pair-fed cyanamide (a selective aldehyde dehydrogenase inhibitor) with and without ethanol. The number of hepatocytes showing positive fluorescence in the presence of both primary and secondary IgGs was significantly higher in rats fed cyanamide plus ethanol than in rats fed cyanamide only. Of note, the 37 kDa protein-AA could be detected by immunotransblot in liver cytosol of alcohol-fed rats but not in the controls of both experiments with and without cyanamide supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic alcohol ingestion on the binding of high density lipoproteins to rat hepatic membranes: involvement of apolipoprotein E

Feeding alcohol to rats produces high density lipoproteins (HDL) particles that exhibit lowered apolipoprotein (apo) E:apo A1 ratio. In this study, we have carried out experiments to compare the abilities of apo E-deficient HDL particles of the alcohol-fed rat and apo E-sufficient HDL particles of the control rat to bind to hepatic membranes. When rat hepatic membranes were incubated with rat serum HDL of physiological concentrations (< or = 200 micrograms HDL-apo A1/ml), binding of HDL to hepatic membranes showed concentration dependent on HDL-apo A1. Polyclonal antibodies that specifically recognize apo A1 and apo E inhibited HDL binding to hepatic membrane while the antibody against apo AIV did not. The binding of 125I-apo A1-HDL was diminished by adding excess amount of unlabeled HDL to the incubation mixture. Apo E-deficient serum HDL obtained from alcohol-fed rats competed less efficiently against radiolabeled HDL for binding to rat hepatic membrane than normal HDL from control animals. The defect in apo E-deficient serum HDL obtained from alcohol-fed rats can be corrected by preincubation with added purified apo E. We hypothesize that this weaker binding may result in slower degradation of apo E-deficient HDL particles by the liver and in part explains the higher plasma HDL levels found in alcohol-drinking animals.

Effects of alcohol feeding on synthesis and secretion of apolipoproteins by regenerating rat sciatic nerve

The amounts of apolipoprotein (apo) E and A1 released into the culture medium were examined in the regenerating nerves distal to a crush site following chronic alcohol feeding. Cultured minced segments of regenerating nerves taken from rats fed an alcohol-containing liquid diet for 5 weeks released only 50% of apoE but nearly 200% of apoA1 when compared with rats pair-fed with a control diet. The extent of decrease in medium apoE corresponded to the decrease of apoE mRNA in the nerve. Thus, chronic alcohol ingestion affects apoE synthesis of regenerating nerves by changing its mRNA level. On the other hand, apoA1 mRNA remained undetectable in regenerating and intact nerves whether the rats were fed alcohol or not. Furthermore, the amount of apoA1 released by the regenerating nerve into the culture medium was not significantly larger than that present in the nerve tissue prior to incubation. Therefore, it is most likely that apoA1 released by the injured nerve originated from the bloodstream and the increase in apoA1 content seen in the crushed nerve of alcohol-fed rats is due to an enhanced permeability of the nerve-blood barrier. Since the burst of apolipoproteins in the injured nerve is likely to play a role in nerve regeneration, the perturbation of apolipoprotein contents in regenerating nerves by chronic alcohol consumption may contribute to the pathogenesis of alcoholic neuropathy.

A novel treatment of global cerebral ischaemia with a glycine partial agonist

Chronic treatment of gerbils with 1-aminocyclopropanecarboxylic acid (a high affinity, partial agonist at strychnine-insensitive glycine receptors) resulted in a 3-fold increase in survival, a significant improvement in neurological status, and an extensive protection of vulnerable brain regions following severe forebrain ischaemia. A bolus of 1-aminocyclopropanecarboxylic acid 30 min prior to ischaemia did not further improve outcome compared to gerbils receiving their last injection 24 h prior to ischaemia. These findings are consistent with the hypothesis that chronic treatment with a glycine partial agonist desensitizes the N-methyl-D-aspartate receptor complex. Pharmacological intervention at the strychnine-insensitive glycine receptor may be an effective means of ameliorating the consequences of neuronal degeneration caused by excitotoxic phenomena.

Treatment of severe brain ischemia with di- and tri-Calciphor (dimer and trimer of 16,16'-dimethyl prostaglandin B1)

Following 20 min occlusion of both carotid arteries, female gerbils were subjected to treatment with di- or tri-Calciphor (dimer or trimer of 16,16'-dimethyl prostaglandin B1). Dimer was injected i.p. at 5 and 10 mg/kg at 5 min and again at 24 h, 30 min and 24 h, 60 min and 24 h or 180 min and 24 h postischemia (N = 25/group). Trimer was given i.p. at 5, 10 or 15 mg/kg at 5 min and 24 h postischemia (N = 25/group.) The controls (N = 25) were injected with the vehicle. Neurological status and postischemic survival of the animals were monitored for 14 days postischemia. Survival of the treated gerbils was significantly improved following the treatment with either di- or tri-Calciphor administered at 10 mg/kg at 5 min and 24 h postischemia (36 vs. 68% di- and 64% tri-Calciphor, P less than 0.05), and with di-Calciphor at 5 mg/kg at 180 min and 24 h postischemia (64%). All other treatment regimens with either drug resulted in a numerical, statistically insignificant improvement. In addition, treatment with either drug reduced the intensity of postischemic neurological impairment. Treatment with di-Calciphor injected at 10 mg/kg at 5 min and 24 h post 20 min ischemia substantially reduced the period of postischemic locomotor hyperactivity. The drug had no impact on either body temperature or blood pressure. There is evidence that the effects of Calciphor may be mediated via calcium regulatory mechanisms. The results of the present study are discussed in the light of such possibility.

Somatotopic maps within the zona incerta relay parallel GABAergic somatosensory pathways to the neocortex, superior colliculus, and brainstem

Neurons located in the zona incerta (ZI) of the ventral thalamus project to several regions of the central nervous system, including the neocortex, superior colliculus, and brainstem. However, whether these projections are functionally segregated remains unknown. This issue was addressed here by combining neuroanatomical tracers with immunohistochemical staining for gamma-aminobutyric acid (GABA) and/or parvalbumin, coupled with neurophysiological mapping. GABAergic projection neurons were found in four distinct subregions of the ZI including: (1) the rostral pole of the ZI, from which neurons project to the supragranular layers of the neocortex (especially layer I); (2) the dorsal subregion of the ZI, where both ascending projections to the neocortex and descending projections to the pretectal area were observed; (3) the ventral subregion of the ZI, whose neurons project to the superior colliculus; and 3) the caudal pole of the ZI, from which descending projections to the lower brainstem and spinal cord were observed. Somatotopic representations of the contralateral cutaneous periphery were also identified in the dorsal and ventral subregions of ZI, both of which were found to receive dense direct afferent projections from the trigeminal complex, and dorsal column nuclei. These results suggest that the rat ZI is a major somatosensory relay in the ventral thalamus, carrying feed-forward inhibitory signals to neocortical and subcortical targets, in parallel with the excitatory somatosensory pathways.

Relative sparing of GABAergic interneurons in the striatum of gerbils with ischemia-induced lesions

Striatal gamma-aminobutyric acid (GABA)ergic interneurons express intense immunoreactivity to glutamic acid decarboxylase (GAD), GABA and parvalbumin. The distribution of these cells in the striatum of gerbils was examined 2-90 days after transient occlusion of the common carotid, a procedure which results in a zone of profound neuronal loss in the dorso-lateral sector of the head of the caudate-putamen (striatum), with relative sparing of somatostatinergic and cholinergic interneurons. Despite a marked decrease in GAD immunoreactivity corresponding to the loss of striatal efferent neurons in this area, isolated neurons expressing intense immunoreactivity to GAD and parvalbumin were still observed in the lesioned area, suggesting that striatal GABAergic interneurons are also relatively spared by ischemic insult in the adult gerbil.

Neonatal whisker removal in rats stabilizes a transient projection from the auditory thalamus to the primary somatosensory cortex

A normally transient cross-modal thalamocortical projection from the magnocellular subdivision of the medial geniculate nucleus (MGm) to the primary somatosensory (SI) cortex of rats was found to remain unchanged throughout adulthood following unilateral removal of whiskers in newborn animals. The normal MGm projection to the auditory cortex is not lost in these neonatally whisker-deprived adults rats but some of the MGm neurons send collaterals to both primary auditory and SI cortices. Parallel electrophysiological experiments demonstrated the multimodal character of some MGm neurons, since they responded to both auditory and cutaneous stimulation. These results suggest that the areal distribution in the cortex of thalamocortical projections arising from a multimodal thalamic nucleus, such as the MGm, may be determined during early postnatal development by the normal flow of sensory information from the periphery to the thalamus and that an early postnatal somatosensory deprivation may prevent the normal withdrawal of a cross-modal projection from the MGm to the SI.

[Investigation on renal function of workers exposed to toluene and xylene]

beta 2-microglobulin (beta 2-M), albumin (Alb), IgG, Protein in urine were measured in 59 workers exposed to toluene, and xylene, and 70 workers not so exposed as control. The results showed that the urine levels of beta 2-M, Alb in exposed groups were significantly higher and increased progressively with increasing work time. Urinary beta 2-M showed significantly positive correlation with Alb, protein. Conformability of beta 2-M, Alb with other renal damage indexes seems better. It is suggested that toluene and xylene might cause renal damage, changes of urinary beta 2-M and Alb concentrations might be used as sensitive indexes for early detection of renal dysfunction in toluene and xylene workers.

Thalamic plasticity induced by early whisker removal in rats

Neurophysiological mapping was used to study the effects of early postnatal removal of mystacial whiskers on the organization of cutaneous receptive fields (RFs) within the ventral posterior thalamus (VP) of rats. This sensory deprivation induced an extensive reorganization of the thalamus, as reflected in larger facial or continuous overlapping face-body RFs and a higher proportion of slowly-adapting responses. Mapping of the VP of young rats (2-3 weeks old) demonstrated that the functional organization of the immature VP thalamus resembles that of the sensory-deprived VP, suggesting that an early postnatal sensory deprivation may interfere with the normal process of thalamic development.

Formation of a 37 kilodalton liver protein-acetaldehyde adduct in vivo and in liver cell culture during chronic alcohol exposure

With the use of antibodies that can recognize acetaldehyde adducts and the application of various immunological techniques, several protein-AAs have now been shown to form in vivo during chronic alcohol ingestion. These protein-AAs include the 37-kDa liver protein-AA, the CytP450IIE1-AA, hemoglobin-AA, two serum protein-AAs with molecular weights of 50 kDa and 103 kDa, and collagen type I protein-AA in liver. If acetaldehyde is the agent responsible for alcoholic liver injury, acetaldehyde toxicity in chronic alcohol ingestion must be linked to the ability of acetaldehyde to form adducts with proteins and perhaps other macromolecules. This is at least one mechanism of acetaldehyde-mediated liver injury. For proteins that serve critical functions, acetaldehyde adduct formation may alter their functions and thereby produce organ damage. Acetaldehyde adduct formation can also elicit humoral or cytotoxic immune responses and these responses may also lead to organ injury.

Effect of chronic ethanol feeding on high density lipoprotein subfractions in rats

We have reported previously that chronic alcohol consumption in the rat produced elevated total serum high density lipoprotein (HDL) fraction, but HDL particles of the alcohol-fed rat were deficient in apolipoprotein (apo) E. In that report, serum HDL particles were prepared by successive ultracentrifugation method and there were concerns that the apo E deficiency in HDL particles was artificially produced by centrifugal forces. In the present report, apo Al affinity column chromatography was used instead of successive ultracentrifugation and it likewise yielded HDL particles from alcohol-fed rats that exhibited lower apo E: apo Al ratio than HDL from control rats (0.185 +/- 0.016 vs. 0.303 +/- 0.017, respectively). When the total serum lipoprotein fraction (d less than 1.21) was analyzed by high performance liquid chromatography (HPLC), both HDL and VLDL peaks were higher in alcohol-fed rats than controls. The size of apo E deficient HDL particles from alcohol-fed rats determined by HPLC did not differ from that of normal HDL particles. When HDL (1.063 less than d less than 1.21) was subfractionated into HDL2 (1.063 less than d less than 1.125) and HDL3 (1.125 less than d less than 1.21), only HDL2 of alcohol-fed rats showed lowered apo E: apo Al ratio when compared with same HDL subfraction of control animals. Therefore, the molecular structure of only HDL2 (but not HDL3) was affected by alcohol-feeding. Another HDL subpopulation which is enriched with apo E, i.e. HDL1 (1.054 less than d less than 1.063), was also prepared.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of the 37KD protein-acetaldehyde adduct in liver during alcohol treatment is dependent on alcohol dehydrogenase activity

Protein-acetaldehyde adducts (protein-AAs) are formed in vivo during chronic alcohol ingestion. These protein-AAs reported thus far include a 37KD protein-AA in liver cytosol, cytP450IIE 1-AA in hepatic microsomes, hemoglobin-AA, and serum protein-AAs. It has been postulated that acetaldehyde or perhaps a reactive acetaldehyde radical generated by the microsomal ethanol oxidizing system (MEOS or cytP450IIE1) explains the formation of the cytP450IIE1-AA. The source of acetaldehyde responsible for the formation of the cytosolic 37KD protein-AA has not been determined. In this report, we have examined the effects of pyrazole (an ADH inhibitor) and cyanamide (an aldehyde dehydrogenase inhibitor) on the formation of the 37KD liver protein-AA in vivo and in vitro. It was found that feeding rats with an alcohol-containing liquid diet supplemented with cyanamide enhanced while a diet supplemented with pyrazole completely abolished the formation of the 37KD liver protein-AA. The liver of rats fed the pyrazole supplemented alcohol-containing diet showed significantly higher content of cytP450IIE1 than that of rats fed the diet containing alcohol alone. On the other hand, feeding the cyanamide supplemented alcohol-containing liquid diet did not further enhance the content of cytP450IIE1. Similarly, adding cyanamide to the culture medium enhanced while adding 4-methylpyrazole inhibited the production of the 37KD protein-AA by cultured hepatocytes even though the combination of alcohol and 4-methylpyrazole increased the content of cytP450IIE1 2-fold over that in control cells. These results demonstrate that the formation of the 37KD liver Protein-AA is dependent on ADH and not on MEOS.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein-acetaldehyde adducts in serum of alcoholic patients

Enzyme-linked immunosorbent assay (ELISA) was used to detect the presence of protein-acetaldehyde adducts (-AAs) in human serum samples. Two methods were compared: (1) direct ELISA: samples, rabbit anti-hemocyanin-AA IgG, and beta-galactosidase (beta-gal) conjugated goat anti-rabbit serum IgG added to a 96-well ELISA plate in a stepwise manner; and (2) two-site or sandwich ELISA: serum samples added to an ELISA plate that had been precoated with anti-hemocyanin-AA IgG (the capture antibody) and incubated stepwise with biotinated anti-hemocyanin-AA IgG (the signal antibody) and avidin-beta-gal conjugates. Serum protein-AA levels were then assayed by bound beta-gal activities at OD405. When human hemoglobin (Hgb)-AA was used as a model protein-AA for the sandwich ELISA, the EC50 (estimated concentration that corresponds to 50% of the OD405 response range) was 7 ng/ml. Direct ELISA was less sensitive (EC50 of 120 ng/ml). Adding control human serum to Hgb-AA increased the EC50 of the direct ELISA more than the sandwich ELISA. Intra- and interassay coefficients of variance for sandwich ELISA were both about 8%. Detection of Hgb-AA by sandwich ELISA was highly specific. The above results with anti-hemocyanin-AA IgG were also obtained when anti-myoglobin-AA IgG was used in sandwich ELISA. Using sandwich ELISA and anti-hemocyanin-AA IgG, OD405 for sera of control subjects and alcoholic patients were 0.036 +/- 0.033 (+/- SEM, n = 28) and 0.150 +/- 0.088 (n = 28), respectively. Serum protein-AAs reacted more strongly with anti-myoglobin-AA IgG than anti-hemocyanin-AA IgG.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of the 37-kD protein-acetaldehyde adduct in primary cultured rat hepatocytes exposed to alcohol

We have previously reported that a 37-kD liver protein formed an adduct with acetaldehyde in vivo when rats were fed alcohol chronically. To understand the mechanism of the formation of this protein-acetaldehyde adduct, rat hepatocytes in primary culture were treated with ethanol in vitro for several days. When cultured in hormone-enriched and trace metal-enriched Waymouth's medium, alcohol dehydrogenase activities in hepatocytes decreased only about 30% during 6 days of culture. At the end of the specified time, protein extracts of hepatocytes were immunotransblotted with rabbit immunoglobulin G that recognized acetaldehyde adduct as an epitope. The 37-kD protein-acetaldehyde adduct band could be detected within 3 days in cells that had been treated with alcohol at a steady-state concentration as low as 5 mmol/L. Although the maximal intensity was obtained at approximately 10 to 40 mmol/L ethanol, addition of cyanamide (an inhibitor of aldehyde dehydrogenase) further increased the intensity of this protein-acetaldehyde adduct band by more than twofold. A good correlation existed between acetaldehyde concentration in the medium and the intensity of the 37-kD protein-acetaldehyde adduct band. Formation of the 37-kD liver protein-acetaldehyde adduct is thus dependent on acetaldehyde, and the 37-kD protein is apparently unusually susceptible to chemical modification by acetaldehyde.

Further studies on the 37 kD liver protein-acetaldehyde adduct that forms in vivo during chronic alcohol ingestion

We have previously reported the detection of a 37 kD liver protein-acetaldehyde adduct in rats fed alcohol chronically with the AIN'76 diet. It was surprising that only one liver protein-acetaldehyde adduct was found. In this report, we have tried to detect additional protein-acetaldehyde adducts by electroimmunotransblot with rabbit anti-hemocyanin-acetaldehyde adduct IgG and to further characterize the 37 kD liver protein-acetaldehyde adduct. Sensitivity of electroimmunotransblot increased 10- to 20-fold when alkaline phosphatase-linked antibody was used in place of horseradish peroxidase, but only one protein-acetaldehyde adduct band was detected in liver. Feeding rats the Lieber-DeCarli alcohol diet also did not produce more protein-acetaldehyde adduct bands in electroimmunotransblot. Addition of cyanamide, an aldehyde dehydrogenase inhibitor, to the AIN'76 alcohol diet greatly increased the intensity of the 37-kD protein-acetaldehyde adduct band on electroimmunotransblot but did not produce other bands. The 37 kD protein-acetaldehyde adduct decayed in vivo with a half-life of 4 days when alcohol was removed from the diet. The 37 kD protein-acetaldehyde adduct in liver is cytosolic. Its interaction with anti-hemocyanin-acetaldehyde adduct IgG was blocked by polylysine-acetaldehyde adduct and polytyrosine-acetaldehyde adduct. It could be removed by immunosorption with anti-hemocyanin-acetaldehyde adduct IgG-bound immunoresin. When immunoblotted with anti-alcohol dehydrogenase and anti-aldehyde dehydrogenase antibodies, the alcohol dehydrogenase and aldehyde dehydrogenase bands in liver of alcohol-fed rats showed identical intensities before and after immunosorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum high-density lipoprotein particles of alcohol-fed rats are deficient in apolipoprotein E

Effects of chronic ethanol consumption on serum lipoproteins have been studied in the rat. The serum levels of triglycerides, cholesterol, phospholipids and apolipoproteins AI and AIV increased significantly after 1 week of ethanol feeding, and they remained elevated up to 7 weeks of alcohol drinking. By contrast, serum total apolipoprotein E decreased or, sometimes, did not change. Very-low-density lipoprotein cholesterol, triglycerides and very-low-density lipoprotein apolipoprotein E of the alcohol-fed rats increased in parallel and were about 2- to 2.5-fold over the controls. Whereas high-density lipoprotein cholesterol, phospholipids, apolipoprotein AI and AIV increased 1.2-fold by chronic alcohol feeding, the level of high-density lipoprotein apolipoprotein E decreased to 70% of that of the control rats. The rates of secretion of apolipoprotein AI, E and AIV into the culture medium by hepatocytes isolated from ethanol-fed rats were 1.8-, 1.3- and 1.1-fold higher than those from control rats. These data indicate that (i) chronic ethanol feeding increases very-low-density lipoprotein and high-density lipoprotein in the rat; (ii) serum high-density lipoprotein particles of the ethanol-fed rats are deficient in apolipoprotein E, and (iii) chronic ethanol feeding increases hepatic secretion of apolipoprotein AI, E and AIV. Since the steady-state serum level of apolipoprotein E decreases or remains unchanged in the presence of increased hepatic apolipoprotein E secretion, this imbalance suggests that alcohol feeding either accelerates the rate of degradation of serum apolipoprotein E or suppresses apolipoprotein E synthesis by nonhepatic tissues.

A family showing inheritance of the Inab phenotype

An 86-year-old white American woman was found to have a very rare red cell phenotype, the Inab phenotype. Her cells were Cr(a-), Tc(a-b-c-), Dr(a-), Es(a-), WES(a-b-), and IFC-. Unlike the two other Inab phenotype patients, she has no history of protein-losing enteropathy or any similar intestinal disorder. One of her four siblings also has the Inab phenotype, providing the first evidence that this phenotype may be inherited. Serum inhibitions showed that anit-Cra, -TCa, -Dra, -WESb, and -IFC are partially inhibited by sera from three siblings with the common red cell phenotype but not by serum from the Inab phenotype sibling. The serum of the proposita contained an antibody to a high-frequency antigen that showed characteristics of being a Cromer-related antibody.

Effects of hormones on apolipoprotein secretion in cultured rat hepatocytes

When rat hepatocytes were cultured in serum-free and hormone-free Waymouth's medium, secretion rates of apolipoproteins (apo) AI and AIV were stable for two days, while the secretion rate of apo E decreased only 20% on the second day. Effects of insulin and dexamethasone on hepatic secretion of apo AI, apo E, and apo AIV were studied in primary culture of rat liver cells within two days. Adding insulin alone and dexamethasone alone, 1 mumol/L each, to cultured hepatocytes for 20 hours had little effect on the amounts of apo AI secreted by the cells. But when the treatment with either insulin or dexamethasone was prolonged for 44 hours, apo AI secretion by treated cells was increased 2.0-fold and 1.4-fold over that by control cells, respectively. If both hormones were added together, secretion of apo AI was synergistically increased 1.5-fold and 7-fold after 20 and 44 hours incubation, respectively. The optimal concentrations of both hormones for the synergistic effect were 0.1 mumol/L. Insulin alone did not affect, while dexamethasone alone slightly suppressed, apo E secretion by hepatocytes. However, when hepatocytes had been incubated with both hormones, a 70% increase in the release of apo E into the culture medium was also observed after 20 hours. Insulin caused a two-fold increase in cellular apo E in hepatocytes. The insulin-mediated cellular accumulation of apo E could be enhanced only very slightly by dexamethasone, but was completely blocked by glucagon.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of a protein-acetaldehyde adduct in the liver of rats fed alcohol chronically

We report here the formation in vivo of a protein-acetaldehyde adduct (protein-AA) in liver when rats were fed alcohol chronically. This chemically modified protein was demonstrated by electroimmunotransblot technique and with rabbit polyclonal antibodies that recognize acetaldehyde adduct as an epitope (i.e., both anti-hemocyanin-AA IgG and anti-myoglobin-AA IgG). It has a molecular weight of 37,000. It can be detected in the liver of rats fed the alcohol-containing American Institute of Nutrition 1976 liquid diet for only 1 wk. Since the protein profiles of soluble hepatic proteins from alcohol-fed and control rats were identical on SDS-PAGE, the peroxidase-positive band demonstrated by electroimmunotransblot was most likely not a new protein synthesized de novo. Borohydride reduction was not necessary to stabilize this protein-AA. Intraperitoneal injections of ethanol (2 g/kg body wt) at 8-h intervals to rats over a 24-h period did not produce any detectable protein-AA in the liver. Incubation of the liver homogenate from a control liver with acetaldehyde without sodium cyanoborohydride for 4 h also failed to generate any protein-AA. Therefore, the formation of the 37-kD protein-AA in vivo reported here is dependent on chronic alcohol consumption.

Differing effects of arginine deficiency on the urea cycle enzymes of rat liver, cultured hepatocytes and hepatoma cells

We have confirmed that arginine-deficient diets increase the liver activities (units per 100 g) of the first four arginine biosynthetic enzymes of the urea cycle in Wistar rats, but not the activity of arginase. In contrast, rat liver cells cultured in monolayers for 48, 72 or 96 h in arginine-free L-15 or minimum essential medium showed no changes in carbamoyl-phosphate synthase (EC 6.3.4.16), ornithine transcarbamylase (EC 2.1.3.3), argininosuccinate synthase (EC 6.3.4.5), argininosuccinase (EC 4.3.2.1) or arginase (EC 3.5.3.1) activities. The arginine content of the cells grown on deficient medium was 36% of that of cells grown on 2.9 mM arginine-sufficient L-15, yet the urea excretion rate into the medium was reduced to 7% of the rate in control cells and the excretion of orotic acid was 400% of that in control cells. A Morris rat hepatoma cell line, 7800C1, which maintains activities of all five urea cycle enzymes, showed no consistent increases in the activities of the first four enzymes when the arginine in the medium was varied between 0 and 2 mM. Thus, in spite of severe arginine deficiency, cultured rat liver cells and hepatoma cells do not show the derepression-like response seen by other investigators when nonliver cells were cultured in arginine-deficient media. The difference between in vivo and in vitro effects of arginine deficiency on urea cycle activities remains unexplained.

Quantification of apolipoproteins in rat serum and in cultured rat hepatocytes by enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) has been developed to measure apolipoproteins in rat serum. Nondelipidated whole serum was heat-treated at 52 degrees C for 3 h in phosphate-buffered saline containing 0.1% Tween-20 before assay. Monospecific rabbit anti-rat apolipoprotein antibodies were added to 96-well polystyrene microtiter plates which had been coated with purified rat serum apolipoproteins or unknown samples. After incubation and washing, goat anti-rabbit serum antibodies conjugated with horseradish peroxidase were added to the plates and incubated. The bound peroxidase activity was assayed after further washing. Serum apolipoprotein concentrations were calculated by comparison against purified standards that were assayed simultaneously with the unknown samples. The intraassay coefficients of variation for apolipoprotein AI, E, and AIV (Apo AI, E, and AIV) were 2.3, 4.4, and 5.3%, and interassay coefficients of variation were 6.1, 5.5, and 7.9%, respectively. The ELISA assay is sensitive to nanogram quantities of rat serum apolipoproteins and the results agree well with those measured by densitometry. The serum concentrations of Apo AI, E, and AIV of a normal fed rat were found to be 504 +/- 8, 413 +/- 20, and 262 +/- 20 micrograms/ml, respectively. When cultured as monolayers in Waymouth's medium for 1 day, rat hepatocytes secreted Apo AI, E, and AIV at rates of 2.51, 61.8, and 48.9 ng protein/mg cell protein/h.

Serum cholesterol, lecithin-cholesterol acyltransferase, and hepatic hydroxymethylglutaryl coenzyme A reductase activities of lean and obese Zucker rats

Serum cholesterol concentrations, lecithin-cholesterol acyltransferase (LCAT), and hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activities of lean and obese Zucker rats were compared. The excess serum cholesterol of the female obese rat is found to be mainly free cholesterol associated with very low-density lipoproteins, whereas that of the male obese rat is carried as cholesterol esters associated with high-density lipoproteins. The high level of serum free cholesterol in the female obese rat is not due to a deficiency in lecithin-cholesterol acyltransferase activity. This enzyme activity is found to be elevated in the male obese rat. Hepatic HMG-CoA reductase activity declines as rats mature; this observation is most apparent in obese male rats. Lean rats exhibit the normal diurnal rhythm, but mature obese rats show little diurnal variation in HMG-CoA reductase activity. Obese female rats maintain high reductase activities, but the activities of obese male rats remain low at all times. Starvation suppresses liver HMG-CoA reductase and serum cholesterol in both lean and obese female rats. Thus, an increase in hepatic cholesterol synthesis may contribute to hypercholesterolemia in the obese female Zucker rat. On the other hand, factors such as nonhepatic synthesis or a decreased cholesterol catabolism may play more important roles in maintaining high serum cholesterol in the obese male Zucker rat.

Secretion of the newly synthesized cholesterol by rat hepatocytes in primary culture

We used monolayer cultured rat hepatocytes as an experimental model to study the secretion of the newly synthesized cholesterol by the liver. Cellular cholesterol was labeled by exposing cultured hepatocytes to [14C]acetate prior to the study of secretion. Secretion of the newly synthesized cholesterol was measured by extracting cholesterol in the culture medium and assaying for the radioactivity of [14C]cholesterol. We found that: (a) cultured hepatocytes could secrete newly synthesized cholesterol in serum-free medium; (b) secreted [14C]cholesterol was bound to macromolecule(s) and the secretion rate was not affected by cycloheximide for up to 5 h; (c) serum added to the culture medium greatly enhanced hepatic cholesterol secretion; (d) serum high-density lipoproteins were most effective, lipoprotein-deficient serum (d greater than 1.21) less effective in stimulating cholesterol secretion, whereas low-density and very-low-density lipoproteins had little effect; (e) when the serum-free culture medium was fractionated by ultracentrifugation, a major portion of the secreted [14C]cholesterol was found in the high-density lipoprotein fraction; (f) part of the medium [14C]cholesterol also turned up in the high-density lipoprotein fraction when lipoprotein-deficient serum was added as the acceptor; (g) secreted [14C]cholesterol was found only in free form, although some of the cellular [14C]cholesterol was found as esters.

Effect of dexamethasone on 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity and cholesterol synthesis in rat liver

Dexamethasone increases reductase activity in cultured liver cells after a lag period of 2 h. The increases of activity are linear from 10(-9) to 10(-5) M dexamethasone, the maximum responses ranging from 2- to 4-fold. The increased reductase activity after dexamethasone treatment is not due to a change of the state of phosphorylation/dephosphorylation of the enzyme nor to an increase of cytosolic activating factor(s) for the reductase. Cholesterol synthesis, measured by incorporation of either [14C]acetate or 3H2O, increases 3-fold after dexamethasone (10(-6) M) treatment, as does the hydroxymethylglutaryl-CoA reductase activity, confirming that this enzyme is rate-controlling for cholesterol synthesis in cultured liver cells as it is in vivo. Dexamethasone (10 micrograms/100 g rat), given after onset of the light cycle, increases reductase activity over control rats at the nadir of the circadian cycle of this enzyme. When given after onset of the dark cycle, dexamethasone does not increase reductase activity over controls at the peak of their circadian cycle. Thus, physiologic doses of glucocorticoids partially reverse the decline in reductase activity due to the circadian rhythm.

Induction of urea cycle enzymes of rat liver by amino acids

To determine which amino acids in a high casein diet are responsible for induction of the five urea cycle enzyme activities in rat liver, we tube-fed 21 L-amino acids singly to rats over 2 days at maximum doses which did not cause toxicity. The results were compared with the 1.3- to 1.9-fold increases (units/100 g rat) obtained by tube-feeding 2 g N/kg for 2 days as casein hydrolysate. Ala (2 g N/kg), Gly /2 g N/kg), Met (0.2--0.4 g N/kg) and Cys (0.4 g N/kg) were the only amino acids which increased all five activities. Moreover, Met. Ala, Gly and casein hydrolysate in these doses increased immuno-precipitable arginase as much as they increased its activity. A combination of Met, Ala and Gly (2 g N/kg) increased all five activities more than 2 g N/kg of casein hydrolysate. Met (0.05 g N/kg) + Ala (0.08 g N/kg) + Gly (0.1 g N/kg), the amounts of these contained in 2 g N/kg of casein, increased all five enzymes in 2 days as much as this dose of casein hydrolysate. Met (0.06 g N/kg) alone increased all five activities (units/100 g rat) 1.2 to 1.4-fold over controls by increasing g liver/100 g rat. Ammonium citrate or acetate tube-feedings over 8 days at 2 g N/kg increased only AS. The keto-acid of alanine, pyruvate, or the alpha-hydroxy acid of methionine did not increase any enzyme whereas the same molar dose of their amino acids increased all five activities. Thus three amino acids of casein, Ala, Gly and especially Met, account for the enzyme adaptation of the urea cycle on a high casein diet.

pH Determination in acidified foods: collaborative study

A proposed method for determining pH of acidified foods has been developed and subjected to collaborative study. The method appears to be both accurate and precise. Five samples consisting of pimientos, marinated pimientos, 2 pH buffer solutions, and chocolate syrup were sent to each of 12 collaborators along with a copy of the method. Two of the collaborators were FDA District laboratories while the remainder were representatives from industry, universities, and state health agencies. Many different types of pH meters and combinations of electrodes were used by the collaborators. The tabulated results from the collaborators are presented. The method has been adopted official first action.

Induction of urea cycle enzymes of rat liver by glucagon

All five urea cycle enzymes of rat liver increased in activity 48 h after subcutaneous administration of crystalline zinc glucagon to male rats and remained elevated after 7 days of continuous glucagon infusion. The maximum ratios of enzyme activities over those of controls were 2.0 for carbamyl phosphate synthetase, 1.3 for ornithine transcarbamylase, 2.7 for argininosuccinate synthetase, 3.2 for argininosuccinase, and 2.2 for arginase. Actinomycin D or puromycin prevented these responses to glucagon. The increase in arginase activity after zinc glucagon treatment was matched by an increase in immunoprecipitable enzyme. All five enzymes were induced by physiological plasma levels of glucagon. Tube feeding of casein hydrolysate for 2 days increased all five enzyme activities 1.5- to 2.2-fold and resulted in plasma glucagon levels similar to those required for induction by exogenous glucagon. Thus, glucagon is an inducer of the entire urea cycle in rat liver and plays a role in the induction of the cycle by protein feeding.

Lysergic acid diethylamide: role in conversion of plasma tryptophan to brain serotonin (5-hydroxytryptamine)

Injections of D-lysergic acid diethylamide decrease the turnover rate of 5-hydroxytryptamine of rat brain, as measured from the conversion of (14)C-tryptophan into (14)C-5-hydroxytryptamine. The 2-bromolysergic acid diethylamide given in doses fivefold greater than those of lysergic acid diethylamide fails to change the rate of (14)C-tryptophan conversion into (14)C-5-hydroxytryptamine. The effect of D-lysergic acid diethylamide is discussed with regard to its action on brain serotonergic neurons and its psychotomimetic effects.