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Biomedical subjects

J L Morgan

Publications and source records attributed to J L Morgan.

At least 37 records · Page 2Linked to original sources
PubMed1993

Quantitation of cytokine levels in skin graft donor site wound fluid.

We quantified endogenous levels of multiple cytokines in skin graft donor site wounds in patients with small to moderate-sized burn injuries. Thirteen patients aged 11 months to 61 years with mean TBSA burn of 4 +/- 1 per cent underwent placement of occlusive wound dressings on partial skin thickness donor site wounds. Fluid was aspirated from beneath the dressing on postoperative day 1 and every subsequent 24 h until no further fluid could be obtained. Interleukin-1 alpha (IL-1) and tumour necrosis factor-alpha (TNF-alpha) levels were determined by enzyme-linked immunosorbent assay (ELISA). Epidermal growth factor (EGF), basic-fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF) were measured by an enzyme immunoassay (EIA). We found substantial levels of EGF and TNF-alpha in the donor site wound fluid in all 13 patients; detectable levels of bFGF in five patients; and elevated levels of IL-1 in three patients. There were no detectable levels of these cytokines in normal human serum. In contrast, there were no measurable levels of PDGF in any patient's wound fluid; the mean level in serum was 1.5 ng/ml +/- 0.2 s.e.m. Studies of cytokines in the normal wound healing environment may help in the design of future therapies to augment wound healing.

Adolescent↗
PubMed1993

Perceptual strategies in prelingual speech segmentation.

Previous work has suggested that infants may segment continuous speech by a BRACKETING STRATEGY that segregates portions of the speech stream based on prosodic cues to their endpoints. The two present studies were designed to assess whether infants also can deploy a CLUSTERING STRATEGY that exploits asymmetries in transitional probabilities between successive elements, aggregating elements with high transitional probabilities and identifying points of low transitional probabilities as boundaries between units. These studies examined effects of the structure and redundancy of speech context on infants' discrimination of two target syllables using an operant head-turning procedure. After discrimination training on the target syllables in isolation, discrimination maintenance was tested when the target syllables were embedded in one of three contexts. Invariant Order contexts were structured to promote clustering, whereas the Redundant and Variable Order contexts were not. Thirty-six seven-month-olds were tested in Experiment I, in which stimuli were produced with varying intonation contours; 36 eight-month-olds were tested in Experiment 2, in which stimuli were produced with comparable flat pitch contours. In both experiments, performance of the three groups was equivalent in an initial 20-trial test. However, in a second 20-trial test, significant improvements in performance were shown by infants in the Invariant Order condition. No such gains were shown by infants in the other two conditions. These studies suggest that clustering may complement bracketing in infants' discovery of units of language.

Acoustic Stimulation↗
PubMed1990

Input, innateness, and induction in language acquisition.

Input and innateness compliment one another in language acquisition. Children exposed to different languages acquire different languages. Children's language experience, however, underdetermines the grammars that they acquire; the constraints that are not supplied by input must be available endogenously, and the ultimate origin of these endogenous contributions to acquisition may be traced to the biology of the mind. To the extent that assumptions of innateness encourage greater explicitness in the formulation of theories of acquisition, they should be welcomed. Excessively powerful assumptions of innateness may not be subject to empirical disconfirmation, however. Therefore, attention should be devoted to the development of a theory of language input, particularly with regard to identifying invariants of input. In combination with a linguistic theory providing an account of the endstate of acquisition, a theory of input would permit the deduction of properties of the mind that underlie the acquisition of language.

Child Language↗
PubMed1990

Imitation of intonation by infants.

Children between 9 and 12 months of age were studied to determine if they would spontaneously imitate either the average fundamental frequency or the fundamental frequency contour of their speaking partners. In the first experiment, children were recorded at home as they interacted with their fathers and mothers. Acoustic analyses failed to reveal any tendency on the part of the infants to adjust vocal pitch, amplitude, or duration to those of their speaking partners. In a second experiment, children were recorded while interacting with their parents in a laboratory setting. Again, there were no indications that the children imitated the vocal patterns of their speaking partners.

Conditioning, Psychological↗
PubMed1989

Limits on negative information in language input.

Hirsh-Pasek, Treiman & Schneiderman (1984) and Demetras, Post & Snow (1986) have recently suggested that certain types of parental repetitions and clarification questions may provide children with subtle cues to their grammatical errors. We further investigated this possibility by examining parental responses to inflectional over-regularizations and wh-question auxiliary-verb omission errors in the sets of transcripts from Adam, Eve and Sarah (Brown 1973). These errors were chosen because they are exemplars of overgeneralization, the type of mistake for which negative information is, in theory, most critically needed. Expansions and Clarification Questions occurred more often following ill-formed utterances in Adam's and Eve's input, but not in Sarah's. However, these corrective responses formed only a small proportion of all adult responses following Adam's and Eve's grammatical errors. Moreover, corrective responses appear to drop out of children's input while they continue to make overgeneralization errors. Whereas negative feedback may occasionally be available, in the light of these findings the contention that language input generally incorporates negative information appears to be unfounded.

Child, Preschool↗
PubMed1985

Distribution and molecular heterogeneity of cholecystokinin-like immunoreactive peptides in the brain and gut of the rainbow trout, Salmo gairdneri.

Cholecystokinin-like immunoreactivity (CCK-li) was measured in extracts of various brain and gut regions of the rainbow trout, Salmo gairdneri. All regions of the brain except the cerebellum and pituitary contained detectable CCK-li. In the gut, the highest concentrations of CCK-li were found in the small intestine and pyloric caeca. Lesser amounts were found in rectum and gastric antrum extracts. In some fish, extracts of these regions contained no detectable CCK-li. Rainbow trout brain extracts contained CCK-li that co-eluted with CCK-8 in gel permeation chromatography whereas CCK-li extracted from the various gut regions exhibited marked molecular heterogeneity. Tissue distribution and apparent molecular size of CCK-li in trout is very similar to mammals for brain but distinct from the mammalian pattern in the gut.

Animals↗
PubMed1984

Contractile responses to MgATP and pH in a thick filament regulated muscle: studies with skinned scallop fibers.

The striated adductor of the Atlantic deep sea scallop ( Placopecten magellanicus ), a thick filament regulated muscle, contains little or no troponin. We examined the effect on activation of two agents (MgATP and pH) that alter the contractile threshold of thin filament regulated muscle, presumably through effects on troponin, to see if they also alter that of thick filament regulated muscle. We find that decreasing MgATP from 2 to 0.1 mM shifts the force-pCa curve of chemically skinned scallop muscle to the left by about 0.8 log units (i.e. Ca2+ sensitivity increases some six-fold). Under similar conditions the force-pCa relation of frog skinned fibers shifts leftward by almost the same amount, 0.7 log units ( Godt , 1974). The force-pCa curve of scallop was unaffected by a decrease in pH from 7 to 6.5. It is especially interesting because: A) the force-pCa relation of skinned fibers from frog (Robertson and Kerrick , 1979) and striated adductor of the Pacific scallop ( Chlamys hastata hericia ) ( Donaldson , unpublished observations) is shifted to the right by about 0.5 log units over this pH range. Furthermore, B) decreasing pH is reported to decrease the calcium affinity of Placopecten myofibrils ( Chantler et al., 1981). Thus the molecular details of thick filament regulation appear to be more complex and varied than hitherto supposed.

Adenosine Triphosphate↗
PubMed1984

Reduced disability and health care costs in an industrial fitness program.

A prospective longitudinal study of a group of participants in an industrial physical fitness program during a five-year period compares the disability and major medical costs incurred by the subjects before and after entry into the program. The members of the cohort were employees of an insurance company; most were well educated and held sedentary, white-collar jobs. Participation was voluntary and without financial incentives. The group experienced 45.7% reduction in major medical costs in the postentry year, rather than the expected inflationary increase. There was a reduction of 20.1% in the average number of disability days, and a 31.7% reduction in direct disability dollar costs in the one-year postentry period. The average combined savings per participant were $353.38; the average operational cost was $120.60. Results suggest that work-site wellness programs can make a substantial contribution to the reduction of health care and disability costs.

Absenteeism↗
PubMed1984

Monoclonal antibody that preferentially binds polylysine, polyarginine, and histones and selectively decorates nuclei and chromosomes.

A monoclonal antibody, designated J-57, selectively and uniformly decorates the interphase nuclei and mitotic chromosomes of a variety of eucaryotic cells as determined by indirect immunofluorescence. As determined by enzyme-linked immunosorbent assay, however, this monoclonal antibody is not monospecific. It reacts weakly with cytochrome c, RNase A, and brain tubulin. By these tests monoclonal antibody J-57 has broad cross-reactivity similar to that of antisera directed against polylysine. The differential reactions of this monoclonal antibody suggest that it may be a useful immunohistochemical probe for nuclei and chromosomes in whole cells.

Amoeba↗
PubMed1984

Localization and characterization of gastrin/cholecystokinin-like immunoreactivity in the central nervous system of Aplysia californica.

Gastrin/cholecystokinin-like immunoreactivity (G/CCK-LI) was localized by immunocytochemistry in neurons in the central nervous system of Aplysia californica. Neuronal cell bodies were specifically immunostained in the buccal, cerebral, pedal, and abdominal ganglia but not in the pleural ganglia. Neural G/CCK-LI processes were observed in the neuropil of all ganglia and connectives and in some but not all of the peripheral nerves examined. Somata containing G/CCK-LI ranged from 15 to 200 micron in diameter. Ganglionic G/CCK-LI was most efficiently extracted in neutral or basic solutions and consisted mainly of a substance eluting in a volume corresponding to a peptide of between 8 and 17 amino acid residues on gel filtration. This G/CCK-LI diluted in parallel to mammalian gastrin in radioimmunoassays using two antisera differing in their specificities for the bioactive COOH-terminal region of mammalian G/CCK. We conclude that G/CCK-LI is distributed widely in the central and peripheral nervous systems of Aplysia californica and that this immunoreactivity probably represents a small peptide which is similar but not identical to mammalian gastrins and cholecystokinins at the functionally critical COOH terminus.

Amino Acid Sequence↗
PubMed1983

Immunological detection of microtubule poison-induced conformational changes in tubulin.

The interaction of tubulin-microtubule poison complexes with anti-tubulin antisera has been investigated using radioimmunoassay. The binding of the major antiserum used in this study to tubulin does not interfere with the binding of colchicine to the tubulin or affect the decay of the colchicine-binding activity of the tubulin. Conversely, if colchicine is incubated with the tubulin, forming tubulin-colchicine complexes, the tubulin-colchicine complexes are less efficient competitors for antibody-binding sites than tubulin alone. This is the result of the formation of specific colchicine-tubulin complexes, since tubulin, incubated with lumicolchicine or isocolchicine, behaves as if the tubulin were incubated alone in the radioimmunoassay. When tubulin is incubated with other microtubule poisons, podophyllotoxin or vinblastine, the tubulin-drug complexes have diminished ability to compete with tubulin as did the tubulin-colchicine complexes. These changes observed in the binding of tubulin-microtubule poison complexes to anti-tubulin antisera in a tubulin radioimmunoassay suggest that the binding of colchicine, podophyllotoxin, or vinblastine to tubulin induces subtle conformational changes on the surface of the tubulin dimer involving antigenic determinant sites.

Animals↗
PubMed1982

The validity of a telephone-administered 24-hour dietary recall methodology.

This study assesses the operational feasibility and validity of a unique telephone-administered 24-h dietary recall methodology. Dietary interviews were conducted by telephone with 204 low-income elderly subjects. Food portion size estimation was done using a two-dimensional food portion visual aid the that was mailed to respondents' homes. The mean intakes and distributions of nine nutrients among males and females in the research sample were compared with those reported in the 1971 to 1974 Health and Nutrition Examination Survey. After correcting for time trends in nutrient intake, the mean intake values found in the survey were very similar to those reported by the Health and Nutrition Examination Survey. In testing the frequency distributions of intakes, only two nutrients for women and one for men had statistically significant differences. The telephone-administered dietary methodology thus produced acceptable estimates of the means and distributions of nutrient intakes among groups of individuals and has the potential of markedly reducing the cost, time, logistical, and personnel constraints associated with nutrition surveys.

Aged↗