Ten millennia of hepatitis B virus evolution

[Figure: see text].

Ancient mitochondrial DNA provides high-resolution time scale of the peopling of the Americas

The exact timing, route, and process of the initial peopling of the Americas remains uncertain despite much research. Archaeological evidence indicates the presence of humans as far as southern Chile by 14.6 thousand years ago (ka), shortly after the Pleistocene ice sheets blocking access from eastern Beringia began to retreat. Genetic estimates of the timing and route of entry have been constrained by the lack of suitable calibration points and low genetic diversity of Native Americans. We sequenced 92 whole mitochondrial genomes from pre-Columbian South American skeletons dating from 8.6 to 0.5 ka, allowing a detailed, temporally calibrated reconstruction of the peopling of the Americas in a Bayesian coalescent analysis. The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout the Americas, limited gene flow in South America resulted in a marked phylogeographic structure of populations, which persisted through time. All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate. To investigate this further, we applied a novel principal components multiple logistic regression test to Bayesian serial coalescent simulations. The analysis supported a scenario in which European colonization caused a substantial loss of pre-Columbian lineages.

Early central andean metalworking from mina perdida, peru

Copper and gold artifacts in contexts dated to approximately 3120 to 3020 carbon-14 years before the present ( approximately 1410 to 1090 calendar years B.C.) recovered in excavations at Mina Perdida, Lurin Valley, Peru, show that artisans hammered native metals into thin foils, in some cases with intermediate anneals. They gilded copper artifacts by attaching gold foil. The artifacts show that fundamental elements of the Andean metallurgical tradition were developed before the Chavin horizon, and that on the Peruvian coast the working of native copper preceded the production of smelted copper objects.

Quebrada jaguay: early south american maritime adaptations

Excavations at Quebrada Jaguay 280 (QJ-280) (16 degrees30'S) in south coastal Peru demonstrated that Paleoindian-age people of the Terminal Pleistocene (about 11,100 to 10,000 carbon-14 years before the present or about 13,000 to 11,000 calibrated years before the present) in South America relied on marine resources while resident on the coast, which extends the South American record of maritime exploitation by a millennium. This site supports recent evidence that Paleoindian-age people had diverse subsistence systems. The presence of obsidian at QJ-280 shows that the inhabitants had contact with the adjacent Andean highlands during the Terminal Pleistocene.

A microdialysis study of amino acid concentrations in the extracellular fluid of the substantia nigra of freely behaving GEPR-9s: relationship to seizure predisposition

Substantia nigra (SN) is known to play an important role in seizure generalization. Both excitatory and inhibitory neurotransmitters can modulate this role of SN. Previous studies have shown that GABA as well as aspartate and glutamate participate in seizure regulation through this site. Evidence for such a role comes from studies on the genetically epilepsy-prone rat (GEPR) and other seizure models. In the GEPR, bilateral microinjections of NMDA receptor antagonists in SN block or reduce seizure severity. In order to further evaluate which neurotransmitters are specifically involved at the SN level of seizure regulation in the GEPR, we undertook a microdialysis study of K+ stimulated release of amino acids in the SN of GEPR-9s- and non-epileptic controls. A 1 mm loop-type microdialysis probe was inserted through pre-implanted guides into the SN of awake and freely moving rats (seven GEPR-9s and four non-epileptic controls), and used to perfuse a 100 mM K+ (high K+) solution for 2 h. Four 30 microliters samples were collected prior to high K+ stimulation (basal release), during high K+ perfusion, and after high K+ infusion. After precolumn derivatization with phenylisothiocyanate, levels of aspartic (ASP) and glutamic (GLU) acids, glycine (GLY), taurine (TAU) and GABA were measured by reversed phase high performance liquid chromatography. Two hours after the initiation of high K+ infusion, the increases relative to basal were, for non-epileptic controls, 35%, 74%, 68%, 847% and 283% respectively for ASP, GLU, GLY, TAU and GABA. Corresponding increases for GEPR-9s were 14%, 10%, 41%, 505% and 123% respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of norepinephrine in forebrain and brainstem seizures: chemical lesioning of locus ceruleus with DSP4

The role of norepinephrine in regulating brainstem seizures has been well documented. These seizures are characterized by running/bouncing clonus and tonic extensor convulsions. Evidence for noradrenergic regulation of brainstem seizures comes partially from studies with genetic models of epilepsy which are characterized by innate noradrenergic deficits and from selective lesioning of noradrenergic neurons and/or pathways. The present study was conducted to evaluate whether destruction of the noradrenergic system using DSP4 (N-(2-chloroethyl)-N-2-bromobenzylamine) influences forebrain seizure severity. Accordingly, 90 female Sprague-Dawley rats (49-55 days old) received DSP4 (50 mg/kg ip) after a pretreatment of desipramine (a norepinephrine reuptake inhibitor), fluoxetine (a serotonin reuptake inhibitor), or saline. A control group of 30 animals received two administrations of saline. Three weeks later, these animals were tested for facial and forelimb clonus (FFC) threshold (convulsive current50; CC50) via corneal electroshock stimulation. The FFC CC50 thresholds in the animals treated with saline plus DSP4 were significantly reduced compared to control (vehicle-vehicle) values. Also, desipramine pretreatment, which partially protected the noradrenergic system from the neurotoxicity of DSP4, completely obviated the reduction in FFC thresholds. A subsequent evaluation of brainstem seizure response using maximal electroshock through earclip electrodes confirmed the noradrenergic influence on brainstem seizure regulation. These observations provide additional support for a noradrenergic role in forebrain as well as brainstem seizure regulation.

The paradoxical effect of NMDA receptor stimulation on electrical activity of the sensorimotor cortex in freely behaving rats: Analysis by combined EEG-intracerebral microdialysis

This study was designed to determine the effects of N-methyl-D-aspartate (NMDA) receptor stimulation on the electrical activity of neocortex in freely behaving rats. Electroencephalogram (EEG) recording and intracerebral microdialysis were conducted simultaneously in the same site of the sensorimotor cortex, where the basal extracellular concentrations of aspartate and glutamate were 2.1 +/- 0.7 microM and 11.5 +/- 2.4 microM, respectively. Microdialysis with NMDA solutions (ranging from 10.0 microM to 10.0 mM) reduced the amplitude of the EEG activity and decreased the power of all frequency bands, with a virtual elimination of the high frequency waves, in a dose-dependent manner. These EEG changes were reversed after washing out the drug from the microdialysis fluid, and could be effectively antagonized with the competitive NMDA receptor antagonist DL-2-amino-5-phosphonovalerate. Remarkably, the NMDA actions were not associated with epileptiform behavioral or electrographic events. Control studies demonstrated that in the same experimental conditions, cholinergic receptor agonist carbachol caused seizures, and microdialysis with NMDA in the hippocampus readily induced epileptiform spikes. Our study shows that NMDA receptor stimulation in the rat sensorimotor cortex, although excitatory at synaptic level, can depress the local EEG activity. This may indicate that the NMDA receptor-mediated signals are processed by the neocortical network in a different way than by many other brain circuitries including hippocampus.

The combined EEG-intracerebral microdialysis technique: a new tool for neuropharmacological studies on freely behaving animals

In this study we combined EEG and intracerebral microdialysis techniques in freely behaving rats. Various drugs were delivered into the hippocampus and cerebral cortex by means of microdialysis and, simultaneously, the EEG activity of the dialyzed area was monitored. The microdialysis procedure itself, when artificial cerebrospinal fluid was perfused, did not change the normal hippocampal or cortical EEG pattern. Drug inclusions into the microdialysis fluid, however, caused marked changes in the electrical activity of the dialyzed sites. In this report we present the following examples: (1) the dose-dependent spike-provoking effect of NMDA in hippocampus, (2) the potentiation of this NMDA effect in hippocampus by dibutyryl cyclic AMP, and (3) the EEG depressant effect of high concentration of K+ in the cerebral cortex. The artificial cerebrospinal fluid and drug solutions were alternated in the microdialysis system with a 2-way valve placed outside the test chamber. As a consequence, the drugs were delivered into the brain without interrupting the ongoing behavior, including sleep, of the examined animals. This study shows that the combined EEG-intracerebral microdialysis technique is a useful tool, with many unique advantages, for in vivo neuropharmacological studies.

Evidence that carbamazepine and antiepilepsirine may produce a component of their anticonvulsant effects by activating serotonergic neurons in genetically epilepsy-prone rats

In order to investigate the mechanism of action of anticonvulsant drugs, we examined the effects of carbamazepine (CBZ) and antiepilepsirine (AE) on convulsions and on brain biogenic amines in genetically epilepsy-prone rats (GEPR). AE was an effective anticonvulsant in moderate seizure GEPR (GEPR-3, ED50 = 65.5 mg/kg) and in severe seizure GEPR (GEPR-9, ED50 = 68.5 mg/kg). Because GEPR are known to have deficiencies in brain norepinephrine (NE) and serotonin (5-HT), which are of etiologic significance in their seizure predisposition, we evaluated the effects of anticonvulsant doses of CBZ and AE on dialyzable NE, 5-HT and their metabolites. Dialysis probes were stereotaxically inserted into hippocampi of awake and unrestrained GEPR-3 and GEPR-9. Either AE (100 mg/kg in GEPR-3; 100 mg/kg in GEPR-9) or CBZ (45 mg/kg in GEPR-3; 6 mg/kg in GEPR-9) was administered i.p. after establishing basal release. Significant increases in dialyzable 5-HT, but not NE, were seen at the approximate time to peak anticonvulsant effect for each drug in both strains. The changes in 5-HT release remained closely associated with the anticonvulsant actions after i.v. administration of either AE (40 mg/kg) or CBZ (25 mg/kg) in GEPR-3. Pretreatment of GEPR-9 with p-chlorophenylalanine depleted brain 5-HT and greatly diminished the anticonvulsant effectiveness of both drugs. We conclude that both CBZ and AE are effective anticonvulsants in GEPR and that enhancement of serotonergic transmission may contribute to the anticonvulsant effect of these drugs.

Effects of fluoxetine on convulsions and on brain serotonin as detected by microdialysis in genetically epilepsy-prone rats

Fluoxetine, an antidepressant and inhibitor of serotonin reuptake, was evaluated as an anticonvulsant in genetically epilepsy-prone rats (GEPRs) because seizure predisposition in GEPRs is partially dependent on deficits in brain serotonin. Fluoxetine produced dose-dependent reductions in sound-induced convulsion intensity in both moderate seizure GEPRs and severe seizure GEPRs with the peak anticonvulsant effect occurring 4 hr after i.p. administration. A subchronic study in severe seizure GEPRs demonstrated that the ED50 after 28 days of dosing (8.2 mg/kg) was lower than the acute ED50 (15.9 mg/kg) so that there was no apparent development of tolerance. The lower ED50 after subchronic administration apparently resulted from accumulation of fluoxetine and its metabolite norfluoxetine in brain. Brain microdialysis studies showed that acute fluoxetine administration resulted in a significant increase in extracellular serotonin concentration in the thalamus. The increase in serotonin concentration in the dialysate corresponded temporally with the anticonvulsant effect produced by fluoxetine. Intrathalamic administration of fluoxetine via the dialysis probe caused an increase in serotonin concentration in the dialysate, suggesting that the effect of fluoxetine was on nerve terminals. Fluoxetine could be dialyzed from thalamus after its i.p. administration. Fluoxetine concentration in the thalamic dialysate was similar to the concentration found in plasma. We conclude that fluoxetine is an effective anticonvulsant in GEPRs and that the microdialysis results strongly suggest a relationship between the effects of fluoxetine on serotonergic neurons and the anticonvulsant effect produced by this drug.

Amino acids, monoamines and audiogenic seizures in genetically epilepsy-prone rats: effects of aspartame

It has been suggested that aspartame facilitates seizures in man and animals because phenylalanine, one of its major metabolites, interferes with brain transport of neurotransmitter precursors and alters the synthesis of monoamine neurotransmitters such as norepinephrine, dopamine and/or serotonin. This facilitation is purportedly more likely in subjects predisposed to seizures. One test of this hypothesis would be to administer a wide range of aspartame doses to subjects whose seizure predisposition is dependent on abnormalities in monoaminergic function. Genetically epilepsy-prone rats (GEPRs) have a broadly based seizure predisposition that is based, in part, on widespread central nervous system noradrenergic and serotonergic deficits. Further reductions in the functional state of these neurotransmitters increases seizure severity in GEPRs. Thus, GEPRs appear ideally suited for testing the hypothesis that aspartame facilitates seizures by interfering with central nervous system monoamines. Oral administration of acute (50-2000 mg/kg) or sub-chronic (up to 863 mg/kg/day for 28 days) doses of aspartame did not alter seizure severity in either of two types of GEPRs. Not surprisingly, acute aspartame doses produced dramatic changes in plasma and brain amino acid concentrations. Hypothesized alterations in monoamine neurotransmitter systems were largely absent. Indeed, increases in norepinephrine concentration, rather than the hypothesized decreases, were the most evident alterations in these neurotransmitter systems. We conclude that aspartame does not facilitate seizures in GEPRs and that convincing evidence of seizure facilitation in any species is lacking.

Aspartame fails to facilitate pentylenetetrazol-induced convulsions in CD-1 mice

Concentrations of plasma amino acids and brain monoamines as well as pentylenetetrazol-induced seizures were monitored in CD-1 mice treated with aspartame in acute oral doses from 0 to 2500 mg/kg. One hour after administration aspartame produced increases in plasma concentrations of phenylalanine and tyrosine and modest reductions in concentrations of brain serotonin and 5-hydroxyindole acetic acid. However, these effects of the sweetener had no influence on the convulsive dose fifty (CD50) of pentylenetetrazol. Moreover, aspartame failed to alter the percentage of mice exhibiting seizures when exposed to an approximate CD50 of pentylenetetrazol. Finally, aspartame had no effect on brain norepinephrine or dopamine concentrations. In sharp contrast to previously reported studies, these observations suggest that aspartame, given in heroic doses, does not alter the propensity to seizure activity in CD-1 mice. We conclude that changes in plasma amino acids and brain serotonin produced by large oral bolus doses of aspartame are insufficient to result in functional deficits which might have the capacity to facilitate pentylenetetrazol-induced seizures.

Primary amyloidosis presenting as a unilateral hilar mass. Report of a case diagnosed by fine needle aspiration biopsy

A case of unilateral hilar amyloidosis in a 69-year-old man was diagnosed by fine needle aspiration (FNA) biopsy and confirmed by ultrastructural studies. The roentgenographic presentation of amyloidosis solely as a unilateral hilar enlargement is extremely rare, with only one case previously reported in the English literature; this appears to be the first case of hilar amyloidosis diagnosed by FNA biopsy.

The role and fate of rabbit and human transcobalamin II in the plasma transport of vitamin B12 in the rabbit

Previous studies have shown that plasma transcobalamin II (TCII) facilitates the cellular uptake of [57Co] vitamin B12 (B12) by a variety of tissues, but the lack of an intrinsic label on the protein moiety of the TCII-B12 complex has made it impossible to determine the role and fate of TCII during this process. We have labeled homogensous rabbit and human TCII with 125I-labeled N-succinimidyl-3-(4-hydroxyphenyl) propionate and have performed in vivo experiments in rabbits. When 125I-labeled rabbit TCII-[57Co] B12 and 131I-labeled bovine albumin were simultaneously injected intravenously, we observed that 125Iand 57Co were cleared from plasma at a faster rate (t1/2 = 1 1/2 h) than 131I and that 125I and 57Co were present in excess of 131I in the kidney, liver, spleen, heart, lung, and small intestine 1/2 h after injection. Later, 57Co remained in excess of 131I, but the ratio of 125I to 131I decreased progressively in all of these plasma and were rapidly excreted in the urine. After 1 h following injection, 57Co was present in excess of 125I in the plasma...

Isolation and characterization of a novel vitamin B12-binding protein associated with hepatocellular carcinoma

High levels of a novel vitamin B12-binding protein (hepatoma B12 BP) have been observed recently in plasma obtained from three adolescent patients with hepatocellular carcinoma. This protein has now been isolated in homogeneous form from the plasma and pleural fluid of two of these patients by the use of affinity chromatography with vitamin B12-Sepharose. The hepatoma B12 BP belongs to the R-type group of B12-binding proteins and is essentially indistinguishable from the recently isolated human milk and saliva R-type proteins in terms of: (a) immunologic properties based on immunodiffusion and immunoprecipitation assays; (b) amino acid composition; (c) molecular weight based on amino acid and carbohydrate content; and (d) absorption spectra. Both hepatoma B12 BPs contain more sialic acid and less fucose than the milk and saliva B12 BPs. All four proteins contain similar amounts of galactose, mannose, galactosamine, and glucosamine. Differences in sialic acid content appear to account for the differences in electrophoretic mobility that were observed among the four proteins. Differences in total carbohydrate content appear to account for the differences in apparent molecular weight that were observed with both gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Tumor tissue from one of the patients contained 10 times as much R-type protein as did normal liver tissue from the same patient. This suggests, although it does not prove, that synthesis by the tumor is the cause of the high levels of R-type protein found in the plasma of certain patients with hepatocellular carcinoma. Plasma survival studies performed with rabbits indicate that the hepatoma B12 BP has a prolonged plasma survival and suggests that his parameter is also of importance.

Human plasma R-type vitamin B12-binding proteins. II. The role of transcobalamin I, transcobalamin III, and the normal granulocyte vitamin B12-binding protein in the plasma transport of vitamin B12

The normal human granulocyte vitamin B12-binding protein, transcobalamin I, and transcobalamin III, have been labeled with 125I-labeled N-succinimidyl 3-(4-hydroxyphenyl)propionate and utilized for plasma clearance studies performed with rabbits. Both moieties of 125I-labeled granulocyte vitamin B12-binding protein-[57Co]vitamin B12 were cleared rapidly from the plasma (is less than 90% by 5 min) by the liver. After 30 min, the bulk of the 125I reappeared in the plasma in small molecular weight (less than 1000) form and was rapidly excreted in the urine. After 60 min the bulk of the [57Co]vitamin B12 reappeared in the plasma bound to rabbit transcobalamin II and was subsequently taken up by a variety of tissues. Approximately 15% of the 125I-labeled granulocyte vitamin B12-binding protein-[57Co-a1vitamin B12 was excreted intact into the bile during the period from 10 to 80 min after injection. The hepatic uptake of the protein-vitamin B12 complex was blocked by the prior injection of desialyzed fetuin but not by native fetuin. Similar results were obtained with 125I-labeled transcobalamin III-[57Co]vitamin B12. Approximately 90% of both moieties of 125I-labeled transcobalamin I-[57Co]vitamin B12 had prolonged plasma survivals similar to that of 125I-labeled bovine serum albumin. After treatment with neuraminadase, both moieties of the 125I-labeled transcobalamin I-[57Co]vitamin B12 complex were cleared rapidly from the plasma by the liver in a manner that was indistinguishable from that observed in the case of untreated granulocyte vitamin B12-binding protein and transcobalamin III. These observations indicate that desialyzed transcobalamin I and the native forms of the granulocyte vitamin B12-binding protein and transcobalamin III are cleared from plasma by the mechanism elucidated by Ashwell and Morell (Ashwell, G., and Morell A. G. (1974) Adv. Enzymol. 41, 99-128) that is capable of clearing a wide variety of asialoglycoproteins. These observations have implications concerning the function of the human R-type vitamin B12-binding proteins, the nature of the enterohepatic circulation of vitamin B12, the biological significance of the mechanism described by Ashwell and Morell, and the etiology of the increased plasma concentration of human R-type protein that occurs frequently in chronic myelogenous leukemia and occasionally in hepatocellular carcinoma and other solid tumors.

Human plasma R-type vitamin B12-binding proteins. I. Isolation and characterization of transcobalamin I. TRANSCOBALAMIN III. and the normal granulocyte vitamin B12-binding protein

Transcobalamin I and transcobalamin III have been purified approximately 6,000,000- and 3,000,000-fold, respectively, from normal human plasma using a purification scheme consisting of immunoadsorption, dialysis against 7.5 M guanidine HCl to remove endogenous vitamin B12, and affinity chromatography on vitamin B12-Sepharose. The two proteins were separated from each other subsequently by chromatography on DEAE-cellulose. The vitamin B12-binding protein present in granulocytes obtained from normal subjects has been purified approximately 5000-fold using affinity chromatography on vitamin B12-Sepharose as the sole purification technique. The final preparations of all three proteins were homogeneous based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Transcobalamin I and transcobalamin III belong to the R-typed class of vitamin B12-binding proteins and are indistinguishable from each other, and from the human granulocyte, milk, and saliva R-type vitamin B12-binding proteins, when studied by immunodiffusion with rabbit anti-human milk vitamin B12-binding protein sera. The carbohydrate compositions, expressed as moles of carbohydrate per mole of vitamin B12, of transcobalamin I, transcobalamin III, and the normal granulocyte vitamin B12-binding protein, respectively, are: sialic acid, 18, 11, 11; fucose, 9, 20, 24; galactose, 41, 51, 46; mannose, 24, 22, 20; galactosamine, 2, 2, 2; and glucosamine, 46, 54, 46. The high sialic acid content of transcobalamin I appears to account for the fact that this protein elutes after transcobalamin III and the normal granulocyte vitamin B12-binding protein during chromatography on DEAE-cellulose. This observation provides support for the hypothesis that differences among the R-type vitamin B12-binding proteins are due to differences in carbohydrate content. The similarities in carbohydrate composition and other properties of transcobalamin III and the granulocyte vitamin B12-binding protein provide support for the hypothesis that human plasma transcobalamin III is derived from granulocytes. The differences observed between transcobalamin I and the normal granulocyte vitamin B12-binding protein suggest that transcobalamin I may not be derived from granulocytes.

Characterization of ileal vitamin B12 Binding using homogeneous human and hog intrinsic factors

Elucidation of the mechanism of intrinsic factor (IF)-mediated vitamin B(12) (B(12)) binding to ileal binding sites has been hampered by the use of crude or only partially purified preparations of IF in previous studies. We have used homogeneous human IF and hog IF isolated by affinity chromatography to study [(57)Co]B(12) binding to ileal mucosal homogenates. The following observations were made: (a) Human IF-B(12) and hog IF-B(12) were bound to human, monkey, hog, dog, rabbit, mouse, hamster, and guinea pig ileal, but not jejunal, homogenates in amounts significantly greater than free B(12) or B(12) bound to five other homogeneous B(12)-binding proteins; (b) only IF-mediated B(12) binding was localized to ileal homogenates and was inhibited by EDTA; (c) values for the association constant (K(a)) for the various ileal homogenates mentioned above and human IF-B(12) and hog IF-B(12) ranged from 0.3 x 10(9) M(-1) to 13.0 x 10(9) M(-1). Apparent differences in the K(a) for human IF-B(12) and hog IF-B(12) existed in most species; (d) the number of ileal IF-B(12) binding sites per gram (wet weight) of ileal mucosa ranged from 0.3 x 10(12) to 4.9 x 10(12). The same value was always obtained with human IF-B(12) and hog IF-B(12) for any given homogenate preparation; (c) 100-fold excesses of free B(12) or human IF and hog IF devoid of B(12) did not significantly inhibit human IF-B(12) and hog IF-B(12) binding to human and hog ileal homogenates. THESE EXPERIMENTS PERFORMED WITH HOMOGENEOUS IF INDICATE THAT: (a) gastric factors other than IF are not required for B(12) binding to ileal IF-B(12)-binding sites: (b) the mechanism of ileal IF-B(12) binding is different from that of free B(12) or of B(12) bound to non-IF-B(12)-binding proteins; (c) human IF and hog IF have different structures; (d) human IF-B(12) and hog IF-B(12) bind to the same ileal binding sites; and (c) human and hog ileal IF-B(12) binding sites bind free B(12) and human and hog IF devoid of B(12) poorly, if at all.