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Biomedical subjects

F Villagra

Publications and source records attributed to F Villagra.

At least 19 recordsLinked to original sources
PubMed2001

Evidence of activity-dependent withdrawal of corticospinal projections during human development.

OBJECTIVE: To characterize the development of ipsilateral corticospinal projections from birth and compare to 1) development of contralateral projections in the same subjects and 2) ipsilateral corticospinal projections in subjects with unilateral lesions of the corticospinal system acquired perinatally or in adulthood. METHOD: Transcranial magnetic stimulation excited the motor cortex, and responses were recorded bilaterally in pectoralis major, biceps brachii, and the first dorsal interosseus muscles. Subjects studied included 9 neonates recruited at birth, studied longitudinally for 2 years; 85 healthy subjects aged from birth to adulthood; 10 subjects with hemiplegic cerebral palsy; and 8 with hemiplegia after stroke. RESULTS: In neonates, ipsilateral responses had significantly shorter onsets than contralateral responses but similar thresholds and amplitudes. Thresholds within both pathways increased in the first 3 months. Differential development was present from 3 months so that by 18 months ipsilateral responses were significantly smaller and had significantly higher thresholds and longer onset latencies than contralateral responses. A similar pattern of smaller and later ipsilateral responses was observed after transcranial magnetic stimulation of the intact cortex in subjects with stroke. In contrast, subjects with hemiplegic cerebral palsy had ipsilateral responses with onsets, thresholds and amplitudes similar to those of contralateral responses. Significant branching of contralateral corticospinal axons from the intact motor cortex was excluded by cross-correlation analysis. CONCLUSIONS: These data, together with previously published anatomic and radiologic studies, are consistent with activity-dependent corticospinal axonal withdrawal during development and maintenance of increased corticomotoneuronal projections from the intact hemisphere after unilateral perinatal lesions.

Adolescent↗
PubMed2001

Abnormal corticospinal function but normal axonal guidance in human L1CAM mutations.

L1 cell adhesion molecule (L1CAM) gene mutations are associated with X-linked 'recessive' neurological syndromes characterized by spasticity of the legs. L1CAM knock-out mice show hypoplasia of the corticospinal tract and failure of corticospinal axonal decussation and projection beyond the cervical spinal cord. The aim of this study was to determine if similar neuropathology underlies the spastic diplegia of males hemizygous for L1CAM mutations. Studies were performed on eight carrier females and 10 hemizygous males. Transcranial magnetic stimulation excited the corticospinal tract and responses were recorded in biceps brachii and quadriceps femoris. In contralateral biceps and quadriceps the responses had high thresholds and delayed onset compared with normal subjects. Ipsilateral responses in biceps were smaller, with higher thresholds and delayed onsets relative to contralateral responses. Subthreshold corticospinal conditioning of the stretch reflex of biceps and quadriceps was abnormal in both hemizygous males and carrier females suggesting there may also be a reduced projection to inhibitory interneurones. Histological examination of post-mortem material from a 2-week-old male with an L1CAM mutation revealed normal corticospinal decussation and axonal projections to lumbar spinal segments. These data support a role for L1CAM in corticospinal tract development in hemizygous males and 'carrier' females, but do not support a critical role for L1CAM in corticospinal axonal guidance.

Adolescent↗
PubMed1996

Accuracy of reported family histories of essential tremor.

We studied the accuracy of reported family histories of essential tremor (ET) by questioning the patients in our clinic and subsequently by mail and phone. For individuals who continued to report a negative family history, we mailed a screening questionnaire to their first-degree relatives to further ascertain the presence of ET. On initial assessment, 67.7% of patients reported a positive family history of ET, but following all assessments, 96.0% of patients had a positive family history. We conclude that a negative family history of ET is often inaccurate, and that ET is primarily a hereditary disease.

Family↗
PubMed1995

Shooting performance is related to forearm temperature and hand tremor size.

The changes in postural tremor of the hand and the subsequent effect on shooting performance produced by moderate cooling and heating of the forearm were studied in six subjects. Cooling produced a large decrease in tremor size of the ipsilateral hand, whereas warming the limb produced an increase in tremor size. Cooling or warming the forearm did not change the peak frequency of tremor significantly, which was quite stable for each subject. The improvement in shooting performance after cooling the forearm, as measured by grouping pattern of the shots, reached statistical significance and warming caused a significant worsening. This measure of performance was shown to correlate (r = 0.776) inversely with tremor size. The causes and implications of these changes are discussed. It is suggested that local cooling may be useful for people who wish temporarily to reduce tremor in order to improve dexterity for shooting and for other purposes.

Adult↗
PubMed1994

The effect of alcohol on physiological tremor.

Ethanol reduces the size of essential tremor. We here show that, contrary to a recent report, ethanol also causes a large decrease in the size of physiological tremor. As in the case of essential tremor, the frequency is not changed. The reduction in tremor probably explains the well-known link between certain types of skilled activity and alcohol consumption.

Acceleration↗
PubMed1994

Limb temperature and human tremors.

The changes in postural tremor of the hand produced by moderate cooling of the muscles of one forearm have been investigated in 16 normal subjects and in 16 patients with essential tremor. In both groups, cooling produced a profound long lasting decrease in tremor level of the ipsilateral hand. In normal subjects, although cooling reduced the tremor size, the EMG of the active muscle clearly increased. Warming the limb in normal subjects produced an increase in tremor level and decrease in EMG. Cooling or warming the limb did not, however, significantly change the peak frequency which was quite stable for each subject. The results of cooling were compared with a brief period of ischaemia, which also reduces tremor size. Local cooling may be a useful manoeuvre for patients with essential tremor, and for others who wish to reduce their tremor temporarily in order to improve dexterity.

Adult↗
PubMed1993

Metabolic cost and efficiency in two forms of squatting exercise in children and adults.

These experiments investigated the oxygen consumption and work efficiency of adults and children performing identical movement patterns. Adult men (mean age 24) and male children (mean age 12) performed squatting exercises with and without a pause at the lowest point of the squat. The former were termed no rebound squats and the latter were termed rebound squats. Subjects performed the exercises without load and with loads equal to 5%, 10% and 15% of body mass. The results showed that the children consumed 10% more oxygen per unit total body mass than the adults. The gross efficiency of the adults was significantly greater than that of the children. Net and apparent efficiencies were not significantly different between the age groups. Gross and net efficiencies declined with load. Rebound squats required 13% less oxygen than no rebound squats. The gross, net and apparent efficiency of rebound squats was significantly greater than that of no rebound squats. It is suggested that the greater gross efficiencies of adults is related to their lower basal metabolic rate and that the greater efficiency of rebound exercise is related to the storage of energy in elastic tissues.

Adult↗
PubMed1992

[Cardiovascular surgery in Spain in 1991. Registry of operations of the Spanish Society of Cardiovascular Surgery (SECCV)].

The Spanish Society of Cardiovascular Surgery has sent a questionnaire to all 37 cardiovascular surgical groups to know the number and type of cardiovascular operations carried out in our country during 1991. The questionnaire was answered by 36 out of 37. In the year 1991, 21,771 cardiovascular patients have been operated upon and 10,913 interventions with extracorporeal circulation have been carried out: 42.4% in valvular disease, 37.2% in coronary and 11.2% in congenital. The number of operations was 5,415 for vascular disease, 4,627 for valvular, 3,168 for coronary, 1,896 for congenital and 3,741 for pacemaker implantation. The total number of operations in 1991 comparing to those performed during 1988 is similar; but the number of open heart operation and the number of these per cardiac unit and per million population during 1991 have increased 20.5, 13.9 and 24.3% respectively. Coronary and valvular operations have also increased 11 and 27% respectively, as well as the number of pacemaker implanted (30%). The number of congenital cases remains the same and the number of vascular operations has decreased by 7.9%.

Cardiac Surgical Procedures↗
PubMed1986

Aortopulmonary window with anomalous origin of the right coronary artery from the pulmonary trunk.

A case of aortopulmonary window associated with an anomalous origin of the right coronary artery from the pulmonary artery in a 3-month-old boy is reported. Angiographic diagnosis could be difficult because of the simultaneous filling of both great arteries that obscure the origin of the anomalous vessel; however, a careful evaluation of the angiogram may contribute to an accurate diagnosis. The surgical correction of this association of defects requires the connection of the aorta with the anomalous coronary ostium. An intrapulmonary tunneling procedure by means of a baffle is described.

Journal Article↗
PubMed1984

Transposition of the great arteries with ventricular septal defects. Surgical considerations concerning the Rastelli operation.

We studied the anatomy of the ventricular septal defect in 20 heart specimens and eight operated patients with transposition of the great arteries regarding the feasibility of the Rastelli operation. They were divided into three groups. In Group I, comprising eight cases, creation of a left ventricle-aorta connection was not prevented by interposition of the atrioventricular valve tissue, and the ventricular septal defect was large or could be enlarged sufficiently. Thus, the Rastelli operation was feasible in all cases. In Group II, comprising 12 cases, interposition of the atrioventricular valves was not present, but the ventricular septal defect was inadequate in size for a good left ventricle-aorta connection. Small or even medium-sized ventricular septal defects were not enlargeable because of surrounding structures or inadequate septum for resection. In all cases, the ventricular septal defect was a tunnellike structure with two orifices; attempted enlargement would be more difficult at the left ventricular end (not obvious to the surgeon's view) than at the right one. The Rastelli operation was judged inadvisable in these cases. In Group III, comprising eight cases, the Rastelli operation was considered inadvisable because of interposition of atrioventricular valve tissue. The size of the ventricular septal defect and the presence of interposed atrioventricular valves can be diagnosed preoperatively. The presence of enough available space for resection, especially at the left ventricular end, should be determined preoperatively and/or intraoperatively in patients with medium-sized ventricular septal defects requiring enlargement. The anatomy of the ventricular septal defect may significantly alter the surgical approach for patients with transposition of the great arteries and ventricular septal defect.

Echocardiography↗
PubMed1977

Coarctation of the aorta and severe aortic insufficiency: What to repair first?

A new surgical approach is proposed for patients with coarctation of the aorta associated with severe aortic valvular insufficiency. The valvular lesion should be repaired first and the coarctation corrected during a second operation; both interventions should be done during the same hospital stay. We base our approach on the belief that improved coronary perfusion can be achieved when the aortic insufficiency is corrected first. The disadvantages of the opposite surgical approach, such as anticoagulation problems, renal underperfusion, and hypertensive complications are easily avoided.

Adolescent↗