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R Vergara

Publications and source records attributed to R Vergara.

13 recordsLinked to original sources
PubMed2003

Spontaneous voltage oscillations in striatal projection neurons in a rat corticostriatal slice.

In a rat corticostriatal slice, brief, suprathreshold, repetitive cortical stimulation evoked long-lasting plateau potentials in neostriatal neurons. Plateau potentials were often followed by spontaneous voltage transitions between two preferred membrane potentials. While the induction of plateau potentials was disrupted by non-NMDA and NMDA glutamate receptor antagonists, the maintenance of spontaneous voltage transitions was only blocked by NMDA receptor and L-type Ca2+ channel antagonists. The frequency and duration of depolarized events, resembling up-states described in vivo, were increased by NMDA and L-type Ca2+ channel agonists as well as by GABAA receptor and K+ channel antagonists. NMDA created a region of negative slope conductance and a positive slope crossing indicative of membrane bistability in the current-voltage relationship. NMDA-induced bistability was partially blocked by L-type Ca2+ channel antagonists. Although evoked by synaptic stimulation, plateau potentials and voltage oscillations could not be evoked by somatic current injection--suggesting a dendritic origin. These data show that NMDA and L-type Ca2+ conductances of spiny neurons are capable of rendering them bistable. This may help to support prolonged depolarizations and voltage oscillations under certain conditions.

2-Amino-5-phosphonovalerate↗
PubMed2003

Relationship between occlusal curvatures and mandibular deviation in orthodontic patients with temporomandibular disorders.

The aim of this study was to investigate the relationships between occlusal curvature (OC) and frontal craniofacial morphology in patients with and without temporomandibular disorders (TMD), using frontal cephalograms and a sophisticated measuring device (XYZAX S400A). Thirty-seven female orthodontic patients (mean age 24.0 years) were divided into a TMD group (n = 25) and no-TMD group (n = 12). In the TMD group, the lateral OCs of the mandibular second premolar, and first and second molars were significantly deeper on the deviated side than on the non-deviated side, and the anteroposterior OCs of the mandibular second premolar and first molar were also significantly shallower on the deviated side. In the no-TMD group, however, there were no significant differences in OCs between deviated and non-deviated sides. The differences between right and left lateral OCs in the mandibular second premolar and first and second molars, as well as the anteroposterior OCs in the mandibular first and second molars, showed significant correlations with mandibular deviation in the TMD group. On the other hand, in the no-TMD group, there was no significant correlation between OCs and mandibular deviation. The above results suggest that OCs might try to compensate for mandibular deviation in patients with TMD.

Adult↗
PubMed2001

Reduction mammaplasty with superior-lateral dermoglandular pedicle: another alternative.

During a period of 7.5 years, reduction mammaplasty using a superior-lateral dermoglandular pedicle was performed in 213 mammary glands in 112 patients. This procedure is a modification of the original technique by Skoog that takes advantage of its benefits but adds two basic premises: (1) to preserve the integrity of the galactophorous ducts for future nursing and (2) to cause less innervation injury. Patients were followed for an average of 28 months (range, 3 months to 7.5 years). The quantity of extirpated tissue ranged from 310 to 1380 g, with a median of 520 g. The nipple-areola complex migrated 5 to 14.5 cm (median, 7.8 cm). The most severe complication was partial necrosis of the nipple-areola complex, which occurred in five cases (four patients). This complication occurred only during the first 2 years of the study, in breast resections larger than 800 g, and with migrations larger than 10 cm. This problem resulted in a modification of the technique, and the complication has not occurred for the past 5 years. There were no important alterations in the sensibility of the nipple-areola complex nor in the integrity of the galactophorous ducts. The long-term satisfaction of the patients was high. The authors present an easily designed and accomplishable technique that is applicable to patients with severe hypertrophy and gigantomastia. The technique has a high security index, and the integrity of the mammary gland is maintained to the maximum.

Adult↗
PubMed1999

Genetic variation in Fitzroya cupressoides (alerce), a threatened South American conifer.

Fitzroya cupressoides (alerce, Cupressaceae) is a large and exceptionally long-lived conifer, endemic to a restricted area of southern Chile and neighbouring areas of Argentina. As a result of its high economic value, the species has been severely exploited for timber, and remnant populations are fragmented and often highly disturbed. The species is thought to have undergone a major range contraction during the last glaciation. In order to assess the extent of genetic variation using DNA markers within and between populations of this species, samples were obtained from throughout the natural range and analysed for random amplified polymorphic DNA (RAPD) variation. Eight 10-mer and three 15-mer primers were used to produce a total of 54 polymorphic bands. Shannon's diversity estimates were calculated to provide an estimate of the degree of variation within each population. Values varied from 0.343 to 0.636 with only the lowest value differing significantly from the others (Spop = 0.547). This indicated that there is a significant degree of variation within each population, and did not provide evidence for genetic 'bottle-neck' effects within the species. A pairwise distance measure calculated from the RAPD data was used as an input for principal coordinate (PCO) and AMOVA analyses. The first three principal coordinates of RAPD distances described 8.3, 5.9 and 5.4% of the total variance, respectively, and a degree of clustering of samples according to their geographical origin was detectable. AMOVA analysis indicated that although most of the variation (85.6%) was found within populations, a significant proportion (P < 0.002) was attributable to differences between populations. An UPGMA dendrogram constructed using phi ST values derived from AMOVA produced a pattern broadly similar to that produced by the PCO, highlighting differences between three main groups of populations within Chile: those from the northern Coastal Range, the southern Coastal Range and Central Depression, and the Andes. Populations from Argentina also emerged as significantly different from those in Chile. These results are interpreted in the context of the postglacial history of the species, and their implications for the development of conservation strategies for Fitzroya are discussed.

Conservation of Natural Resources↗
PubMed1995

Glucocorticoid reserve in patients with acquired immunodeficiency syndrome.

The purpose of the study was to determine the glucocorticoid reserve in patients with AIDS. Thirty patients with AIDS, who were not critically ill, were chosen consecutively and studied prospectively over a 1-year period with cosyntropin-stimulation testing. All patients showed normal glucocorticoid response to cosyntropin stimulation. Clinical adrenal insufficiency is uncommon in patients with AIDS who are not critically ill.

Acquired Immunodeficiency Syndrome↗
PubMed1994

[Postoperative analgesia for ambulatory surgery in children: a comparison of 2 techniques].

In 40 children scheduled for circumcision, we studied the quality and the adverse effects of postoperative analgesia induced by caudal block (group 1) or acetaminophen by rectal route (group 2). Study lasted the six first postoperative hours. In recovery room, analgesia was more effective in group 1. Need of analgesic drugs was also lesser in group 1. Incidence of adverse effects was the same in the two groups.

Acetaminophen↗
PubMed1993

Elevated serum thyrotropin [TSH] levels in critically ill patients with acquired immunodeficiency syndrome (AIDS).

STUDY OBJECTIVE: To determine thyrotropin (TSH) reserve in critically ill patients with Acquired Immunodeficiency Syndrome (AIDS). DESIGN: Prospective longitudinal. SETTING: Six hundred (600) bed municipal hospital serving a poor neighborhood in New York City with a high incidence of AIDS mainly from intravenous drug abuse. PATIENTS AND METHODS: Twelve (12) patients with AIDS, who were in the Intensive Care Unit or critically ill on medical wards, were evaluated consecutively with baseline thyroid function tests and serum thyrotropin (TSH) response to thyroid releasing hormone testing. RESULTS: 66.7% of patients had elevated TSH levels. All patients had low triiodothyronine (T3), six patients had low thyroxine (T4) levels. RESULTS: (cont'd). Six patients met the criteria for hypothyroidism. Two patients met the criteria for subclinical hypothyroidism. CONCLUSION: Elevated TSH levels and hypothyroidism are common in our critically ill population with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1980

Studies of mutagenicity on quiescent and proliferating hamster cell populations.

A few known mutagens were tested on proliferating hamster cells and on cells made quiescent by L-histidinol block. No differences were found in the effectiveness of two alkylating agents and a base analogue; whereas the carcinogen 4-nitroquinoline-1-oxide was more effective on quiescent than on proliferating cells. The implications of these data on the mechanism of action of mutagens are discussed.

4-Nitroquinoline-1-oxide↗
PubMedDate not supplied

Intramuscular gluteal implants.

The authors present a new space for the placement of gluteal implants in augmentation gluteoplasty. Placement of implants in this intramuscular anatomical space offers a good cosmetic result and seems to satisfy the demands of augmentation gluteoplasty in terms of safety, reproducibility, and esthetics.

Adolescent↗