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Biomedical subjects

D A Martin

Publications and source records attributed to D A Martin.

At least 55 records · Page 3Linked to original sources
PubMed1989

Nurses' involvement in ethical decision-making with severely ill newborns.

This study was an exploratory investigation of the extent and nature of nurses' reported participation in the resolution of treatment dilemmas for infants with severe congenital anomalies. Participants in the study were 83 registered nurses from neonatal intensive care units in five large urban hospitals in the Southwest. Data were collected through the use of intensive semi-structured interviews with each participant and nurse responses to an investigator designed case study instrument, The Nursing Ethical Decision-Making Scale. Results indicated that a majority (85%) of the nurses in the study do not participate in a substantial way in decisions to initiate or forego life-sustaining treatment for their infant patients, yet they bear the major responsibility for implementing those decisions. The lack of participation in the decision-making process was cited by 70% of the nurses as being a major source of occupational stress and ethical anguish. Nurses with graduate educational preparation or advanced clinical practitioner education tended to take a more active role in decision-making. Other factors that appeared to promote participation in decision-making included nurse perceptions of administrative support for involvement, the existence of internal mechanisms for communication about treatment dilemmas (including infant care review committees), and hospital affiliation with a medical school. Eighty-seven percent of the nurses identified themselves as the infant's primary advocate, but only 20% of that group reported that they would pursue decisions through the chain of command outside the neonatal unit if they believed that an infant was not receiving appropriate treatment.

Adult↗
PubMed1988

Projective determinacy.

It is shown that projective determinacy follows from large cardinal axioms weaker than the assertion that supercompact cardinals exist.

Journal Article↗
PubMed1988

Contact-lens correction of aphakic infants and children: early behavioral and VEP results.

We studied 11 infants and young children fitted with contact lenses for correction of unilateral or bilateral aphakia. The visual-acuity estimates obtained from behavioral cues (alternate-cover test and central-fixation monitoring) were compared with results obtained from pattern-reversal visual-evoked potentials (VEP). We conclude that VEP may be more sensitive than behavioral observation for monitoring the visual progress in certain aphakic children.

Aphakia↗
PubMed1987

Alteration of the visual evoked potential by macular holes: comparison with optic neuritis.

Nine patients with maculopathy (macular holes, macular cysts, and lamellar holes) and ten patients with optic neuritis were examined in order to determine changes in the visual evoked potential (VEP) in response to pattern-reversal stimulation. Eyes with lamellar holes had normal P100 latency, but eyes with macular cysts and macular holes had prolonged P100 latency. Eyes with optic neuritis exhibited greater prolongation of the P100 latency than eyes with macular holes. In contrast, eyes with macular holes had a greater reduction in the steady-state VEP amplitude than eyes with optic neuritis. The prolonged latency occurring in maculopathy may be due to a peculiar amplitude summation noted with half-field VEP, rather than to a true conduction delay like that seen in eyes with optic neuritis. The amplitude slope, which is usually positive in normal controls, was negative for 85.7% of eyes with macular holes and 69.2% of eyes with optic neuritis. The negative amplitude slope may represent a subtle defect in retinal ganglion X cells. Eyes with significantly lower values for four or more of the nine central test points on quantitative automated perimetry had negative amplitude slopes and prolonged P100 latency.

Adult↗
PubMed1986

The electroretinogram in advanced open-angle glaucoma.

Fourteen patients with advanced open-angle glaucoma were evaluated prospectively by electroretinography and the results were compared with normal controls who were matched for age and sex. All glaucoma patients had visual acuity of 20/50 or better, cup-to-disc ratios of 0.7 or greater in at least one eye, and visual field loss consistent with advanced glaucoma. Numerous electroretinographic parameters were significantly abnormal when compared with the control group.

Adult↗
PubMed1986

Computer analysis of Farnsworth-Munsell 100-hue test.

Color vision abnormalities indicated by the Farnsworth-Munsell 100-hue Color Vision Tests (FM-100) were analyzed by computer to better characterize and group congenital and acquired color vision disorders and to help establish statistically significant diagnostic criteria. Standard evaluation of the FM-100 is by axis and error score calculations. A method has been established for computer-averaging many tests from patients with the same color abnormalities determined by history, standard FM-100 and Nagel anomaloscope. The computer calculated an average error score and standard deviation for each of the 85 color caps. Every time a new patient was evaluated for color vision abnormality, his score was compared with averaged tests with common diagnoses, by calculating distance scores. The averaged test with the lowest distance score consistently tended to coincide with the diagnosis. An analysis of 130 FM-100 color tests found technician-calculated error scores to be incorrect, although usually minor, in 40% of the tests. The computer-calculated axes agreed well with the technician's estimates. The distance scores predicted the diagnosis accurately 89% of the time. Many errors were due to the small number of protanopes averaged and inability to distinguish trichromats from dichromats.

Color Perception Tests↗
PubMed1986

Taurine supplementation in infants receiving long-term total parenteral nutrition.

Twenty-one children and 23 adults receiving long-term total parenteral nutrition (TPN) for 27 +/- 23 (SD) months were investigated to determine if they were taurine-deficient because the TPN solutions were taurine-free. The fasting plasma taurine level was reduced in the children to 26 + 13 mumol/liter vs the control 57 +/- 16 mumol/liter (P greater than 0.001). The plasma taurine level was significantly reduced in those adults who absorbed less than 25% of their nutritional needs from their diet. Electroretinograms were abnormal in each of eight children who were examined; isolated cone and rod implicit times were both significantly delayed. Electroretinograms were not abnormal in those adults with low plasma taurine levels. Taurine was added to the TPN solutions of four children, and the plasma taurine level became normal in each of them. Electroretinograms of three of these children became normal. One year after discontinuing intervenous taurine supplementation, the plasma taurine level became abnormal in two of three children. These observations indicate that children, and possibly adults, receiving long-term TPN have a nutritional requirement for taurine.

Adult↗
PubMed1986

Immune complexes in synovial fluid and serum from patients with disseminated gonococcal infection: evidence for local immune complex formation within the joint.

Twenty one patients with acute arthritis associated with disseminated gonococcal infection (DGI) were studied. Synovial fluid (SF) from 14 and serum from 15 (matched in eight) were assayed for the presence of immune complexes (IC) by the Raji cell immunofluorescent assay (Raji IFA) and the 125I-Clq polyethylene glycol (PEG) binding assay. Higher levels and frequency of IC were detected in the SF by both IC assays and these were associated with a significant increase in complexes containing IgM over serum (p less than 0.02). Complexes containing IgG were found predominantly in serum and were infrequent in SF (p less than 0.003). These data suggest that the arthritis of DGI may result from primary immune complex formation within the synovial cavity after local antibody synthesis within the synovium in response to gonococcal seeding.

Antigen-Antibody Complex↗
PubMed1985

Nutritional requirement for taurine in patients receiving long-term parenteral nutrition.

Animals fed diets lacking the amino acid taurine have low plasma and tissue levels of taurine and ultimately have retinal dysfunction. Since parenteral nutrition does not ordinarily provide taurine, we looked for evidence of taurine deficiency in 21 children and 23 adults undergoing long-term parenteral nutrition at home for an average of 27 +/- 23 (S.D.) months. The fasting plasma taurine level was reduced in children as compared with controls (26 +/- 13 vs. 57 +/- 16 mumol per liter, P less than 0.001). In adults with less than 25 per cent intestinal absorption of the recommended caloric intake, the plasma taurine level was also significantly reduced and correlated inversely with the duration of parenteral nutrition. Electroretinograms were abnormal in each of eight children who were examined. Addition of taurine to the intravenous solutions restored plasma levels to normal in four children; the electroretinograms of three of these children also became normal. The plasma taurine level became abnormally low again in two of three children one year after the intravenous taurine was discontinued. We conclude that children and possibly adults receiving long-term parenteral nutrition have a nutritional requirement for taurine.

Adolescent↗
PubMed1985

Eye movement abnormalities in rod monochromatism and blue-cone monochromatism.

Eye movements were recorded with electro-oculography in seven patients with rod monochromatism (RM) and five with blue-cone monochromatism (BCM). The continuous horizontal nystagmus was similar in both groups. However, three patients with BCM demonstrated an intermittent, high-frequency nystagmus, in addition to the continuous nystagmus. The most striking differences between the groups were present during monocular smooth pursuit and optokinetic tracking. Patients with RM demonstrated better tracking when targets moved in the temporal-to-nasal (T-N) direction in the visual field of the viewing eye, than when targets moved in the nasal-to-temporal (N-T) direction. The velocity of optokinetic nystagmus (OKN) increased gradually over several seconds during T-N target movement. Patients with BCM did not show a directional asymmetry or a slow build-up of OKN during monocular tracking. Differences in eye movement abnormalities can be useful in differentiating these two forms of congenital color blindness from other forms of congenital nystagmus and from each other.

Adolescent↗
PubMed1984

Evidence that 5-HT agonist-induced rotational behaviour in the rat is mediated via 5-HT1 receptors.

The rotational behaviour induced by 5-HT agonists has been investigated in rats with lesions of the dorsal raphe' nucleus (DRN). We have previously reported that 5-methyoxy-N,N-dimethyl-tryptamine (5-MeODMT) caused dose-related contralateral rotation in rats with 5,7-dihydroxytryptamine (5,7-DHT) lesions of the DRN. Similar findings are now presented for the 5-HT1 agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and 5-methoxy-3 (1,2,3,6-tetrahydropyridin-4-yl) (1H indole) (RU24969). In this model, in agreement with the behavioural studies, both agonists were shown to have a greater affinity for the 5-HT1 binding site when compared with the 5-HT2 binding site. Antagonist studies using selective 5-HT2 antagonists (ketanserin and pirenperone) at non-sedative doses failed to inhibit this behaviour. In contrast, the classical 5-HT antagonist methysergide caused significant inhibition of the rotational behaviour. These results suggest that 5-HT agonist-induced rotation in the rat is mediated via 5-HT1 receptors, probably located in the substantia nigra.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1983

Loss of electroretinographic oscillatory potentials, optic atrophy, and dysplasia in congenital stationary night blindness.

New criteria for diagnosing congenital stationary night blindness include loss of the oscillatory potentials in the photopic and bright-flash dark-adapted electroretinogram, and atrophy or dysplastic changes, or both, in the optic nerve head. Ten patients (seven male and three female, ranging in age from 6 to 19 years) had typical findings of congenital stationary night blindness including congenital nonprogressive nyctalopia, no pigmentary retinopathy, and full visual fields consistent with myopia. Visual acuities ranged from 20/30 to 20/60, though one patient had a visual acuity of 20/200. Most patients had histories of strabismus. The photopic electroretinograms were subnormal. Of the male patients, five had tilted optic disks with temporal portions of the nerve missing, and two had misshapen nerve heads. The three female patients had pallor of the optic disk without evidence of tilt.

Adolescent↗