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Biomedical subjects

R Baker

Publications and source records attributed to R Baker.

At least 505 records · Page 28Linked to original sources
PubMed1979

Clinical aspects of continuous neonatal oxygen monitoring.

Twenty newborn infants (gestational age 30--40 weeks, weight 980--3400 g) were studied in two groups to compare two commercially available systems for continuous in vivo oxygen monitoring: the So2 catheter and the transcutaneous Po2 (TcPo2) electrode, and their respective electronic systems. Measurements from these systems were correlated with determinations made from samples intermittently drawn and measured by conventional So2 and Pao2 in vitro methods , respectively. Information about these two in vivo oxygen monitoring systems was then related to our previous experience with the bare-wire earlobe O2a electrode. Measurements from the two in vivo monitoring techniques studied showed good correlations with their respective in vitro oxygen measurements: So2 catheter, y = x - 3.08, r = 0.98 (range studied 74% to 100%) and transcutaneous electrode, y = 0.98x + 0.57, r = 0.89 (range studied 34 to 92 mm Hg). It was concluded that all three systems give a good reflection of central arterial oxygen (either Sao2 or Pao2)). The system to be used in specific clinical situations should depend on condition of the baby and stage of treatment, need for an umbilical line to measure other variables, equipment available, and training of personnel.

Catheterization↗
PubMed1978

Incontinentia pigmenti in a Black baby: a case report.

This is a case report of a Black baby girl who presented at the age of 7 days with incontinentia pigmenti. While the classic 3 phases of inflammation, hyperkeratosis, and irregular pigmentation are the rule, this patient demonstrates an accepted variation, presenting with irregular pigmentation without having gone through the other phases. Ninety-five per cent of the described cases have been in females. A negative family history, as in this case, is not unusual.

Abnormalities, Multiple↗
PubMed1978

Prolonged nitroprusside and intermittent hemodialysis as therapy for intractable hypertension.

Nitroprusside was used with intermittent hemodialysis over a 26-day period in a 6-year-old boy with intractable hypertension. Hemodialysis effectively removed thiocyanate from the blood, thus preventing its accumulation and subsequent toxic manifestations. Prolonged nitroprusside infusion maintained arterial blood pressure at acceptable levels until the patient became responsive to other antihypertensive therapy.

Child↗
PubMed1978

Go-kart injuries.

The pattern and number of injuries which have occurred over a period of 4 years at Aviemore Kart Tract are described. Some of the modifications which have significantly reduced the number and severity of the injuries are discussed.

Athletic Injuries↗
PubMed1978

Active cables for use with dry electrodes for electrocardiography.

With the active cables described in this paper, it is possible to record the electrocardiogram with dry electrodes. Simultaneous recordings of the ECG from dry electrodes via the active cables and from conventional electrodes with electrode paste demonstrate that there is no discernible difference in the electrocardiographic waveforms.

Electrocardiography↗
PubMed1978

Exogenous prostaglandins and gastric secretion in the cat.

1. In the conscious gastric fistula cate PGE2 was shown to produce dose-related inhibition of gastric acid and pepsin secreted in response to pentagastrin, histamine and insulin. 2. PGF2alpha had little effect on pentagastrin-stimulated gastric acid and pepsin secretion. 3PGF2 delayed the tachyphylaxis of gastric acid stimulated by pentagastrin and histamine, but not that stimulated by insulin. 4. Although not delaying tachyphylaxis of insulin stimulated acid, PGE2 delayed tachyphylaxis of insulin stimulated pepsin.

Animals↗
PubMed1978

Endogenous prostaglandins and gastric secretion in the cat.

1. The gastric juice outputs of acid, pepsin, PGE and PGF, and the plasma concentrations of PGE and PGF have been measured in response to I.V. infusions of pentagastrin, histamine and insulin in the conscious cat. 2. There were significant correlations between the output of gastric acid and gastric outputs of both PGE and PGF during secretion produced by all stimulants. Furthermore, there were similar significant correlations between the gastric outputs of pepsin and both PGE and PGF. However, during insulin stimulation there was significantly more pepsin output per unit PGE or PGF output than during either pentagastrin or histamine stimulation. 3. The correlations between the outputs of gastric acid and both PGE and PGF were similar during pentagastrin and insulin stimulation whereas those between acid and PGE and PGF altered during the infusion of histamine. 4. It is concluded that these data partially, but not entirely, support the hypothesis that local release of prostaglandins may act as a negative feed-back mechanism on gastric acid secretion. 5. Plasma prostaglandin concentration did not correlate with changes in acid or pepsin secretion.

Animals↗
PubMed1978

Excitatory termination of abducens internuclear neurons on medial rectus motoneurons: relationship to syndrome of internuclear ophthalmoplegia.

1. Field potentials and intracellular records were obtained from the medial rectus subdivision of the IIIrd nucleus in anesthetized cats following electrical stimulation of the abducens nuclei, vestibular nerves, pontomedullary brain stem, and the medial longitudinal fasciculi (MLF). 2. Stimulation of the contralateral abducens nucleus produced unique field potentials in the medial rectus subdivision. They consisted of an early sharp transient volley followed by a slower postsynaptic negativity. 3. Monosynaptic EPSPs were evoked in medial rectus motoneurons following contralateral abducens nucleus stimulation. The EPSP amplitudes were graded when the stimulus intensity was increased from threshold to supramaximal. EPSPs produced by contralateral abducens nucleus stimulation were larger in amplitude than those produced by ipsilateral vestibular nerve stimulation. The current-voltage relationship and reversal potentials for Vi- and abducens-evoked EPSPs were similar and indicated an overlapping location of excitatory synaptic terminals on medial rectus motoneurons. 4. Secondary vestibular axons activated monosynaptically by ipsilateral vestibular nerve stimulation were not recruited by abducens nucleus stimulation. 5. Ipsilateral MLF stimulation produced EPSPs with similar profiles as those observed following abducens nucleus stimulation; however, stimulation of the contralateral MLF at comparable stimulus intensities did not produce any changes in transmembrane potential. 6. When higher intensity stimuli were applied to the contralateral MLF, the synaptic potentials recorded in the medial rectus were occluded by those produced by weaker stimulation applied to the ipsilateral MLF. This suggests that the potentials resulting from stronger contralateral stimulation were due to current spread to the ipsilateral MLF. 7. While recording in the medial rectus subdivision, various sites in the ponto-medullary brain stem were explored with a stimulating electrode. Analysis of evoked field potentials suggested that the ascending internuclear axons were contained only in the MLF ipsilateral to the medial rectus. Acute brain stem lesions confirmed this suggestion. 8. Chronic lesions were placed in the brain stem to isolate the abducens nucleus from either extrinsic fibers of passage or axon collaterals. Acute electrophysiological experiments in these chronic animals corroborated the suggestion that the medial rectus pathway originated from within the abducens nucleus. 9. We conclude that axons from the internuclear neurons of the abducens nucleus exit from the nucleus medially, cross the midline, ascend in the opposite MLF, and terminate monosynaptically on medial rectus motoneurons. 10. we believe that the syndrome of internuclear ophthalmoplegia associated clinically with lesions of the medial longitudinal fasciculus could be due to the absence of ascending physiological activity from internuclear neurons of the abducens nucleus.

Abducens Nerve↗
PubMed1978

Bitter medicine.

Explore the source record for details and available documents.

Economics, Hospital↗
PubMed1977

Bilateral lesions of the medial longitudinal fasciculus in monkeys: effects on the horizontal and vertical components of voluntary and vestibular induced eye movements.

Bilateral transections across the brainstem interrupted the medial longitudinal fasciculus (MLF) in three monkeys trained to make eye movements while subjected to horizontal or vertical angular accelerations. Eye movements measured before and after the lesion revealed deficits in both voluntary and vestibular compensatory eye movements; the deficits differed in the horizontal and vertical directions. Vertical saccades in both directions were normal but eccentric positions of fixation could not be maintained; a drift toward the midline followed by a corrective saccade produced vertical fixation nystagmus. Furthermore, the vertical vestibulo-ocular reflex (VOR) was abolished and vertical smooth pursuit was impaired. Along the horizontal meridian, adduction across the midline could not be achieved during either saccades, smooth pursuit, or the VOR. Temporal saccades were normal whereas nasal saccades were considerably slowed. If the eye was not required to cross the midline, the phase shift during the VOR was within 15 deg of normal in each eye. The gain of the VOR was reduced to about 0.4 immediately after the lesion, but recovered within one month. These findings suggest that the MLF transmits quite different kinds of information to horizontal and vertical oculomotoneurons and that deficits in vertical eye movements may be a sensitive indicator of anterior internuclear ophthalmoplegia.

Animals↗
PubMed1977

[Excitatory effect of the superior colliculus on the motor neurons of extra-ocular muscles of cats].

The synaptic actions which might underline the caccadic eye movements induced by stimulation of the superior colliculus have been studied in the unanesthetized cat "encéphale isolé". Intracellular recordings of extraocular muscle medial rectus motoneurons have revealed a minimally disynaptic excitatory projection from the superior colliculus to the ipsilateral medial rectus motoneurons (latency 1.3 to 2.6 msec).

Action Potentials↗