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Biomedical subjects

M Perea

Publications and source records attributed to M Perea.

At least 19 recordsLinked to original sources
PubMed2001

Nasolacrimal stents in the management of epiphora: medium-term results of a multicenter prospective study.

PURPOSE: To evaluate in a prospective multicenter setting the clinical utility of polyurethane stents in the percutaneous management of epiphora. MATERIALS AND METHODS: Patients (N = 163; age range = 22-85 y, mean = 52 y; 29 men, 134 women) with severe epiphora had stents (n = 183) inserted under fluoroscopic guidance in 180 lacrimal systems (unilateral = 146; bilateral = 17) to treat complete (n = 172) or partial (n = 8) obstruction of the nasolacrimal duct or sac. The junction between sac and duct was the most frequent location (n = 102), followed by the sac alone (n = 48), and the duct alone (n = 30). The etiology of the obstruction was idiopathic in 113 cases (63%) and chronic dacryocystitis in 67 (37%). The set designed by Song was used in all patients and the original technique was slightly modified by the authors. All patients were treated on an outpatient basis. Average time of the procedure was 14 minutes (range = 3-70 min). RESULTS: Initial technical success rate of stent placement was 97%. Resolution of epiphora was complete in 175 eyes and partial in five. On follow-up (mean = 450 d; range = 8-730 d), 157 of 183 stents remained patent (85.8%). Of the 24 obstructed, 19 were easily withdrawn and 17 of these patients remained asymptomatic for a mean of 15 months (secondary patency rate = 89.5%). CONCLUSIONS: The procedure is simple and safe. It can be performed on an outpatient basis and the original technique could be improved with some technical modifications. It is well tolerated by patients and may be considered as a valid alternative technique for the resolution of epiphora.

Adult↗
PubMed2001

Acute quadriplegic myopathy with loss of thick (myosin) filaments following heart transplantation.

Acute quadriplegic myopathy with loss of thick (myosin) filaments (AQM-LTF) is an acute toxic myopathy observed in critically ill patients and is characterized by proximal or diffuse weakness of extremities and difficulty in weaning from mechanical ventilation. In recent years, this myopathy has been described in transplanted patients, although only 5 cases have been reported following heart transplantation. We present 3 new cases and review the previous literature. We conclude that the clinical picture and outcome of AQM-LTF in heart-transplanted patients do not differ from those observed in other critically ill patients (transplanted and non-transplanted). Therefore, because AQM-LTF is often clinically suspected muscle biopsy should be quickly performed to confirm the diagnosis so that physical therapy may begin as soon as possible.

Acute Disease↗
PubMed2000

Aging is associated with increased lipid peroxidation in human hearts, but not with mitochondrial respiratory chain enzyme defects.

BACKGROUND: Aging is associated with increased oxidative damage at multiple cellular and tissular levels. A decrease in mitochondrial function has repeatedly been advocated as a primary key event, especially on the basis of analysis of skeletal muscle mitochondria. However, some doubts on this issue have arisen when confounding variables (such as physical activity or smoking habit) have been taken into account in the analysis of mitochondrial respiratory chain (MRC) enzyme activities or when additional analytical parameters such as enzyme ratios have been considered. OBJECTIVE: To determine whether oxidative damage and enzyme activities of the MRC are influenced by the aging process in human hearts. PATIENTS AND METHODS: We studied cardiac muscle obtained from 59 organ donors (age: 56+/-12 years, 75% men). Oxidative membrane damage was evaluated through the assessment of lipid peroxidation. Absolute and relative enzyme activities (AEA and REA, respectively) of complex I, II, III and IV of the MRC were spectrophotometrically measured. Stoichiometric relationships among MRC complexes were also assessed through calculating MRC ratios. Linear regression analyses were employed to disclose any potential correlation between mitochondrial dysfunction and aging. RESULTS: We found a progressive, significant increase of heart membrane lipid peroxidation with aging (P<0.05). Conversely, neither AEA nor REA decreased with age (P=n.s. for all complexes). Similarly to observations in other tissues, we found that stoichiometry of the MRC enzymes is maintained within a narrow range in human hearts. When the effects of aging on MRC ratios were explored, we failed again in demonstrating any subtle disarray. CONCLUSION: MRC enzymes remain preserved in heart with aging, and thus they cannot be considered the main cause of the increased oxidative damage associated with aging.

Adolescent↗
PubMed2000

Congenital and metabolic myopathies of childhood or adult onset.

OBJECTIVES: To investigate the clinical presentation, histological findings, and outcome of patients with congenital and metabolic myopathies (CM and MM) in whom the disease was diagnosed in childhood or adulthood. PATIENTS AND METHODS: We reviewed the diagnosis of all skeletal muscle biopsies performed by our group between 1984 and 1996 (13 years). All patients with CM and MM of childhood or adult onset were included in the study. Patients with mitochondrial myopathies were excluded because they are multisystemic disorders with a more distinct picture than that observed in other MM. We retrospectively reviewed the clinical history, with special emphasis on the clinical patterns of presentation, histological findings, and outcome. RESULTS: Among 1,865 biopsies, 28 (1.5%) fulfilled the diagnostic criteria for CM (seven nemaline myopathies, four multicore myopathies, three centronuclear myopathies) or MM (five adult-onset acid maltase deficiency, three myophosphorylase deficiency, three phosphofructokinase deficiency, two carnitine palmitoyl transferase deficiency, and one carnitine deficiency). In nearly half of the patients, mild stable weakness was the major complaint, whereas in one third muscular symptoms were intermittent and related to exercise. In a small number of cases, a persistently raised serum creatine kinase in an asymptomatic patient was the reason for muscle biopsy. Histological examination of skeletal muscle was highly indicative of a specific muscle disease in 26 of the 28 cases. After a mean follow-up of 7 years, the outcome has generally been good, and in most patients the myopathy did not worsen, most remaining ambulatory. CONCLUSION: CM and MM presenting in childhood or adulthood are infrequent; the symptoms are usually mild or moderate, and the prognosis generally is good.

Adolescent↗
PubMed2000

Repetition and form priming interact with neighborhood density at a brief stimulus onset asynchrony.

The relationships between repetition- and form-priming effects and neighborhood density were analyzed in two masked priming experiments with the lexical decision task. Given that form-priming effects appear to be influenced by a word's orthographic neighborhood, it is theoretically important to find out whether repetition priming also differs as a function of the word's orthographic neighborhood. Within an activation framework, repetition- and form-priming effects are just quantitatively different phenomena, whereas the two effects are qualitatively different in a serial-ordered model of lexical access (the entry-opening model). The results show that repetition- and form-priming effects were stronger for hermit words than for words with many neighbors. These results pose some problems for both activation and serial-ordered models. The implications of these results for determining how neighbors affect the identification of a word are discussed.

Adult↗
PubMed1999

The effects of "neighborhood size" in reading and lexical decision.

The effects of neighborhood size ("N")--the number of words differing from a target word by exactly 1 letter (i.e., "neighbors")--on word identification was assessed in 3 experiments. In Experiments 1 and 2, the frequency of the highest frequency neighbor was equated, and N had opposite effects in lexical decision and reading. In Experiment 1, a larger N facilitated lexical decision judgments, whereas in Experiment 2, a larger N had an inhibitory effect on reading sentences that contained the words of Experiment 1. Moreover, a significant inhibitory effect in Experiment 2 that was due to a larger N appeared on gaze duration on the target word, and there was no hint of facilitation on the measures of reading that tap the earliest processing of a word. In Experiment 3, the number of higher frequency neighbors was equated for the high-N and low-N words, and a larger N caused target words to be skipped significantly more and produced inhibitory effects later in reading, some of which were plausibly due to misidentification of the target word when skipped. Regression analyses indicated that, in reading, increasing the number of higher frequency neighbors had a clear inhibitory effect on word identification and that increasing the number of lower frequency neighbors may have a weak facilitative effect on word identification.

Decision Making↗
PubMed1998

The effects of neighborhood frequency in reading and lexical decision.

To test the effect of the frequency of orthographic "neighbors" on the identification of a printed word, two sets of words were constructed (equated on the number of neighbors, word frequency, and number of letters); in one set, the words had no higher frequency neighbors and in the other set, they had at least one higher frequency neighbor. Identification was slower for the latter set. In Experiment 1, this was indexed by longer response times in a lexical decision task. In Experiment 2, the target words were embedded in sentences, and slower identification was indexed by disruptions in reading: more regressions back to the words with higher frequency neighbors and longer fixations on the text immediately following these words. The latter results indicate that a higher frequency neighbor affects relatively late stages of lexical access, an interpretation consistent with both activation-verification and interactive activation models.

Eye Movements↗
PubMed1997

Associative and semantic priming effects occur at very short stimulus-onset asynchronies in lexical decision and naming.

Prior research has found significant associative/semantic priming effects at very short stimulus-onset asynchronies (SOAs) in experimental tasks such as lexical decision, but not in naming tasks (however, see Lukatela and Turvey, 1994). In this paper, the time course of associative priming effects was analyzed a several very short SOAs (33, 50, and 67 ms), using the masked priming paradigm (Forster and Davis, 1984), both in lexical decision (Experiment 1) and naming (Experiment 2). The results show small--but significant--associative priming effects in both tasks. Additionally, using the masked priming procedure at the 67 ms SOA. Experiments 3 and 4, shows facilitatory priming effects for both associatively and semantically (unassociated) related pairs in lexical decision and naming tasks. That is, automatic priming can be semantic. Taken together our data appear to support interactive models of word recognition in which semantic activation may influence the early stages of word processing.

Adult↗
PubMed1997

Effects of orthographic neighborhood in visual word recognition: cross-task comparisons.

Effects of orthographic neighborhood in visual word recognition in Spanish were examined in 5 paradigms: progressive demasking, standard lexical decision, lexical decision with blocking of neighborhood density, naming, and semantic categorization. The results showed inhibitory effects of neighborhood frequency in the progressive-demasking task, in both lexical-decision tasks, as well as for low-density words in the naming task, and for high-density words in the semantic-categorization task. Higher levels of neighborhood density produced an inhibitory trend in the progressive-demasking task, facilitation in lexical decision (significant only when neighborhood density was blocked), and a robust facilitation effect in naming (only for words with higher frequency neighbors). A global analysis across tasks and one simulation study helped outline some of the underlying task-specific and task-independent mechanisms.

Decision Making↗
PubMed1996

Effects of masked repetition priming and orthographic neighborhood in visual recognition of words.

The role of orthographic neighborhood (neighborhood size and neighborhood frequency) in visual-word recognition was analyzed using the masked repetition-priming paradigm. Specifically, we varied stimulus-onset asynchrony (33, 50, and 67 msec.) and type of prime (identical, unrelated, unprimed) in a lexical decision task. Analyses show additive effects of repetition and stimulus-onset asynchrony. Further, the unrelated condition overestimated the repetition effects relative to an unprimed condition. Facilitatory effects of neighborhood size and inhibitory effects of neighborhood frequency were also found. The results are interpreted in terms of current models of visual-word recognition.

Adult↗