Publications by authors named "Labarca R"

We present the results of the excavations and analyses of the diverse and exceptional archaeological assemblage of Taguatagua 3, a new late Pleistocene site located in the ancient Tagua Tagua lake in Central Chile (34°S). The anthropogenic context is constrained in a coherently dated stratigraphic deposit which adds new information about the mobility, subsistence strategies, and settlement of the early hunter-gatherers of southern South America. The age model constructed, as well as radiocarbon dates obtained directly from a combustion structure, indicate that the human occupation occurred over a brief time span around 12,440-12,550 cal yr BP.

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In deserts, water has been singled out as the most important factor for choosing where to settle, but trees were likely an important part of the landscape for hunter-gatherers beyond merely constituting an economic resource. Yet, this critical aspect has not been considered archaeologically. Here, we present the results of mapping and radiocarbon dating of a truly unique archaeological record.

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Article Synopsis
  • The study aimed to reassess the pathological lesions on a gomphothere found in Chile, using 227 skeletal specimens of a young adult male.
  • Various conditions were identified including vertebral asymmetries, degenerative joint disease, possible neoplastic lesions, and signs of spondyloarthropathy, challenging previous diagnoses of trauma.
  • The findings highlight the need for further investigation into South American gomphothere paleopathology and encourage researchers to re-evaluate specimens in museum collections for overlooked conditions.
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Objective: We aimed to evaluate magnetic resonance imaging (MRI) previously used criteria (Matthews's criteria, MC) for differentiating multiple sclerosis (MS) from neuromyelitis optica spectrum disorders (NMOSD) in Caucasian and non-Caucasian populations (Argentina, Brazil and Venezuela) with positive (P-NMOSD), negative (N-NMOSD), and unknown (U-NMOSD) aquaporin-4 antibody serostatus at disease onset and to assess the added diagnostic value of spinal cord MRI in these populations.

Methods: We reviewed medical records, and MRIs were assessed by two blinded evaluators and were scored using MC. Short-segment transverse myelitis (STM) was added as a new criterion.

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The Younger Dryas (YD) impact hypothesis posits that fragments of a large, disintegrating asteroid/comet struck North America, South America, Europe, and western Asia ~12,800 years ago. Multiple airbursts/impacts produced the YD boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at >50 sites across ~50 million km² of Earth's surface. This proposed event triggered extensive biomass burning, brief impact winter, YD climate change, and contributed to extinctions of late Pleistocene megafauna.

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Proboscideans are so-called ecosystem engineers and are considered key players in hypotheses about Late Pleistocene megafaunal extinctions. However, knowledge about the autoecology and chronology of the proboscideans in South America is still open to debate and raises controversial views. Here, we used a range of multiproxy approaches and new radiocarbon datings to study the autoecology of Chilean gomphotheres, the only group of proboscideans to reach South America during the Great American Biotic Interchange (∼3.

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Introduction: The clinical use of magnetic resonance (MR) in patients with multiple sclerosis (MS) has advanced markedly over the past few years. Several groups around the world have developed consensus guidelines about the role of MR in MS at diagnosis and during follow up. However, in some regions is difficult to extrapolate the recommendations.

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Introduction: This study examined the reproductive function and prevalence of polycystic ovary syndrome (PCOS) in women with bipolar disorder taking antimanic medications.

Method: Women aged 18-45 treated for bipolar disorder and not taking steroid contraceptives were recruited to complete questionnaires about their menstrual cycle and to provide blood samples for measurement of a range of reproductive endocrine and metabolic hormone levels. Eighty women participated in completing the questionnaires and 72 of them provided blood samples.

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We hypothesized that use of mechanical acetabular guides for intraoperative alignment leads to variations between the actual and desired implant orientation. Acetabular implant orientation using only the mechanical guide was studied in 78 patients (82 hips) undergoing primary total hip arthroplasty. A computer-assisted navigation system was used to measure alignment and to monitor the orientation of the pelvis during surgery.

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The purpose of this randomized, prospective study was to compare accuracy in tunnel placement as performed with a traditional arthroscopic anterior cruciate ligament (ACL) reconstruction technique and with KneeNavTM ACL, a computer-assisted surgical navigation technique. Two surgeons experienced in ACL reconstruction, but inexperienced in computer-assisted surgical navigation technique, each randomly used traditional arthroscopic guides or KneeNavTM ACL to drill a tunnel in twenty identical foam knees. Placement of the resulting tibial and femoral tunnels was measured with a computer-assisted digitizing method and compared to traditional biplanar radiographs.

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Repeated amphetamine (AMPH) administration results in behavioral sensitization. To investigate the participation of the opioid system in this phenomenon, we examined the effects of acute and repeated AMPH administration on mu-opioid receptor (MOR) mRNA levels in the nucleus accumbens (NAc) and striatum (STR) of rats, by quantitative non-radioactive in situ hybridization. Five injections of d-AMPH (1.

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There has been little clinical research to examine the effects of patient positioning and pelvic motion on the alignment of the acetabular implant during total hip replacement surgery. Until now, no tools were capable of accurately measuring these variables during the actual procedure. As part of a broader program in medical robotics and computer assisted surgery, a clinical system has been developed that includes several enabling technologies.

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1. The effects of pimozide on the psychopathology of delusional disorder were studied. 2.

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1. The effects of acute D-amphetamine administration to rats on the release of endogenous excitatory amino acids from nucleus accumbens slices were studied. 2.

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In CA1-CA3 hippocampal slices, in vitro ethanol (EtOH) (10-100 mM) evoked, as a function of EtOH concentration, a differential release of aspartate (Asp) and glutamate (Glu). Omission of Ca2+ ions from the superfusion media completely abolished the EtOH-induced release of Asp but not that of Glu. In addition, at 20 mM, EtOH enhanced K(+)-evoked release only of Asp.

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After 5 weeks of haloperidol, positive symptoms in drug-naive schizophrenic patients substantially subsided. Negative symptoms, although with a different temporal pattern, decreased after the fifth week of haloperidol treatment; specifically, a decrease was seen in anhedonia and affective flattening, whereas avolition-apathy and attentional impairment presented no changes. Alogia showed a decrease during the third week and a trend to return to placebo scores during weeks 4 and 5.

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1. The effects of excitatory amino acid agonists on the release of newly-synthesized [3H]dopamine was examined in slices of nucleus accumbens of the rat. 2.

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We report 6 patients with Munchausen syndrome, a fictitious disorder with physical symptoms. There were 4 females and 2 males, the age ranged from 21 to 29 years. Abdominal pain (2), hemoptysis, shock and hypoglycemia were the presenting symptoms.

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The biology of planktotrophic larvae of Concholepas concholepas is the main bottleneck towards developing biotechnologies to rear this muricid. Data concerning planktonic larvae development, diets and environmental signals triggering larval settlement and recruitment is scarce. We have begun the study of the molecular and cell biology of embryos, larvae and recruits having as a final goal, the development of appropriate biotechnologies to rear this gastropod.

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Plasma homovanillic acid (HVA) levels were measured hourly for a 24-hour period in 10 patients with schizophrenia during treatment with placebo and fluphenazine. Ten age- and sex-matched normal volunteers were similarly studied. Diet and activity were carefully controlled and monitored in both patients and controls.

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Plasma and brain levels of the dopamine metabolite, homovanillic acid, were measured in rats after acute and chronic treatment with fluphenazine. After acute administration, homovanillic acid levels were increased in the whole frontal cortex, caudate nucleus, nucleus accumbens, anterior cingulate (supragenual) cortex, prefrontal cortex and plasma. Following chronic administration, the effects of single doses of fluphenazine in increasing homovanillic acid were markedly attenuated in the caudate nucleus, nucleus accumbens, the whole frontal cortex, anterior cigulate cortex and plasma, but not in the prefrontal (anteromedial) cortex.

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The effect of acute swim stress on the functional activity of the gamma-aminobutyric acid (GABA) receptor/chloride ion channel was studied using an assay to measure 36chloride (36Cl-) uptake into rat brain synaptoneurosomes. Muscimol-stimulated 36Cl- uptake in cerebral cortex, hippocampus, but not cerebellum, was enhanced (increased potency and efficacy) in rats subjected to 10 min of swimming, compared to non-stressed, control rats. The effect of swim stress on the activity of the GABA receptor/Cl ion channel was prevented by adrenalectomy.

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Ouabain binds to the catalytic subunit of Na+,K+-ATPase and specific [3H]ouabain binding can be used as a measure of the number of active enzyme molecules present in a given tissue. Specific [3H]ouabain binding can be demonstrated in frozen, cryostat sections from rat brain and pineal and these sites have the characteristics of Na+,K+-ATPase. Incubations carried out in the absence of ATP or the presence of excess unlabeled ouabain reduces specific binding by greater than or equal to 98%.

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