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Biomedical subjects

J M Pearce

Publications and source records attributed to J M Pearce.

At least 235 records · Page 13Linked to original sources
PubMed1985

The differential prenatal diagnosis of cystic hygromata and encephalocele by ultrasound examination.

The difficulty in distinguishing an encephalocele from a cystic hygroma has recently been highlighted by five patients referred to our unit with an incorrect diagnosis of cystic hygroma. A review of the literature revealed four other cases of misdiagnosis. Based on review of 46 patients with one or other diagnosis, we have attempted to establish guidelines to aid diagnosis. We have always been able to identify the bony defect in the fetal vault in cases of encephaloceles. The pattern of the septa is usually characteristic in cystic hygroma.

Diagnosis, Differential↗
PubMed1985

Intrauterine growth retardation.

The many problems of diagnosing IUGR are compounded by a lack of ability to detect the dysmature infant from the constitutionally small infant even at birth. Antenatal attempts at detecting IUGR must start with the accurate establishment of gestational age. This can be only accomplished by routine early ultrasound measurement of BPD for all pregnant patients. Subsequently, management is aimed at screening out a group at high risk for having a growth-retarded fetus. Clinical means are poor but SFH measurements or a repeat ultrasound in the third trimester can be expected to detect about 85% of IUGR patients. Diagnosis of IUGR is made by detailed measurement of growth parameters on a serial basis. The use of the H/A ratio chart allows the antenatal division of IUGR into asymmetric and symmetric, such that appropriate investigation and management can be undertaken. The study of flow velocity waveforms obtained by pulsed Doppler ultrasound might in the future help to provide a more rational basis for referring patients to intensive antenatal fetal monitoring.

Female↗
PubMed1984

Boxers' brains.

Explore the source record for details and available documents.

Athletic Injuries↗
PubMed1984

Doppler blood flow waveforms in the descending thoracic aorta of the human fetus.

A linear-array pulsed Doppler duplex has been used to study third-trimester Doppler flow velocity waveforms (FVW) in the descending thoracic aorta of 98 normal and 20 severely growth-retarded fetuses. Waveforms have been normalized (frequency index profile; FIP) to remove the effect of the angle of insonation and so allow comparison at different gestational ages and with complicated pregnancies. There is an increase in end-diastolic velocities with advancing gestational age indicating a reduction in placental resistance. The growth-retarded fetuses showed a significant reduction in end-diastolic velocities and an increase in the pulsatility index (normal PI: mean 1.83, SD 0.22; growth-retarded PI: mean 2.78, SD 0.60). This reduction of diastolic blood flow may indicate reduced placental vascularity and predict impending fetal hypoxia.

Aorta, Thoracic↗
PubMed1984

Recognition memory in Parkinson's disease.

On four tests of visual recognition memory Parkinsonian patients obtained normal scores, both immediately and after a delay. They also resembled controls closely in nearly all characteristics of memory. Their performance did not correlate with age, motor disability or disease duration. Parkinson's disease does not, therefore, affect this kind of memory.

Adult↗
PubMed1984

The strength of the orienting response during Pavlovian conditioning.

The strength of orienting toward a light that signaled food was studied in five experiments. Experiment 1 demonstrated that this response declined in strength during conditioning but was temporarily restored during extinction. In Experiment 2 the light was again paired immediately with the unconditioned stimulus (US), whereas in Experiments 3 and 4 it signaled a tone which in turn signaled the US. In these three experiments we again found that continuous reinforcement resulted in a decline in the strength of light orientation. These studies also revealed that under conditions of partial reinforcement, orientation to the light was sustained. Experiment 5 demonstrated that the decline in light orientation with a continuous reinforcement procedure can be retarded either by preexposing the light for a number of trials prior to conditioning or by intermixing reinforced light trials with nonreinforced presentations of a tone. This experiment also revealed that reversing the reinforcement contingency associated with the tone restored orientation to the light. This pattern of results can be most readily explained by the proposal that the strength of orientation toward the light is inversely related to the predictive accuracy of this stimulus.

Acoustic Stimulation↗
PubMed1984

Cerebral monitoring of somatosensory evoked potentials during profoundly hypothermic circulatory arrest.

The factors that influence the functional integrity of the central nervous system during clinical procedures involving profoundly hypothermic circulatory arrest (PHCA) have not been objectively evaluated. Intraoperative monitoring of somatosensory evoked potentials (SEPs) was performed in nine infants undergoing PHCA during repair of congenital cardiac anomalies to investigate the short-term effects of this intervention on neurophysiologic function. Latency prolongation of the primary cortical (N18,P22) and cervical spinal cord (N13) responses, reflecting slowing of neural transmission with hypothermia, occurred as a power function of decreasing systemic temperature (p less than .01). The cortical evoked response disappeared during profound hypothermia (less than 18 degrees C), remaining absent throughout the period of circulatory arrest and for a variable period of time after reperfusion. Regression analysis indicated that the time required for the recovery of the cortical evoked response on reperfusion was a linear function of the time-temperature integral of the arrest period (p less than .001) and the pH at the onset of circulatory arrest (p less than .001). Neurologic complications occurred in three patients and included cortical blindness (n = 2) and a generalized seizure disorder (n = 1). Visual dysfunction was not reflected in the intraoperative SEP recordings, whereas prolonged delay of SEP recovery, indicative of global central nervous system injury, was observed in the patient who experienced seizures after the surgery. This preliminary experience with SEP monitoring during PHCA suggests a role for this modality in determining the short-term effects of this procedure on neurophysiologic function. The recovery characteristics of somatosensory neural transmission appear to be modulated by the duration of, and temperature and pH maintained during, the arrest period.

Body Temperature↗
PubMed1983

Lacunar infarcts in polycythaemia with raised packed cell volumes.

Lacunar (small deep cerebral infarcts) infarction is described in association with raised packed cell volumes. Two patients had polycythaemia vera, one stress polycythaemia. They presented with transient ischaemic episodes and were shown by computed tomography to have lacunes deep in the basal ganglia and internal capsule. Such lesions may be caused by small vessel occlusions related to increased viscosity and impaired oxygen consumption by adjacent tissues. Finding a raised packed cell volume in patients with lacunes and transient ischaemic attacks offers a further possibility of treatment.

Aged↗
PubMed1983

New doppler technique for assessing uteroplacental blood flow.

Gated, pulsed, doppler ultrasound was used to study blood flow velocity profiles in the uterine vessels (arcuate arteries) during the second and third trimesters of pregnancy. A frequency index profile nomogram was constructed from 30 normal pregnancies; this demonstrated high diastolic velocity and low pulsatility. Among 31 pregnancies with complications 14 showed waveform changes suggesting raised vascular resistance; these pregnancies were complicated with a high frequency of proteinuric hypertension, poor fetal growth, and fetal hypoxia. This non-invasive technique may give early warning of impaired uteroplacental perfusion and can be used to evaluate methods of improving uterine blood flow.

Doppler Effect↗