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Biomedical subjects

L Richardson

Publications and source records attributed to L Richardson.

13 recordsLinked to original sources
PubMed1991

An intraoral splint for the prevention of microstomia from facial burns.

Microstomia may be a disfiguring complication of severe burn injuries of the soft tissues of the face. The constriction of the perioral myocutaneous tissues following such trauma poses several problems and usually necessitates major plastic and reconstructive intervention. A novel technique is described which limited the anticipated constriction of perioral tissues in a 21-year-old female who suffered full skin thickness burns to 65 per cent of her body, including her face, following a self-induced petrol burn.

Adult↗
PubMed1991

Gastrointestinal health effects associated with the consumption of drinking water produced by point-of-use domestic reverse-osmosis filtration units.

During a prospective epidemiological study of gastrointestinal health effects associated with the consumption of drinking water produced by reverse-osmosis domestic units, a correlation was demonstrated between the bacterial counts on R2A medium incubated at 35 degrees C and the reported gastrointestinal symptoms in families who used these units. A univariate correlation was found with bacterial counts on R2A medium at 20 degrees C but was confounded by the bacterial counts at 35 degrees C. Other variables, such as family size and amount of water consumed, were not independently explanatory of the rate of illness. These observations raise concerns for the possibility of increased disease associated with certain point-of-use treatment devices for domestic use when high levels of bacterial growth occur.

Canada↗
PubMed1991

A randomized trial to evaluate the risk of gastrointestinal disease due to consumption of drinking water meeting current microbiological standards.

BACKGROUND: This project directly and empirically measured the level of gastrointestinal (GI) illness related to the consumption of tapwater prepared from sewage-contaminated surface waters and meeting current water quality criteria. METHODS: A randomized intervention trial was carried out; 299 eligible households were supplied with domestic water filters (reverse-osmosis) that eliminate microbial and chemical contaminants from their water, and 307 households were left with their usual tapwater without a filter. The GI symptomatology was evaluated by means of a family health diary maintained prospectively by all study families over a 15-month period. RESULTS: The estimated annual incidence of GI illness was 0.76 among tapwater drinkers compared with 0.50 among filtered water drinkers (p less than 0.01). These findings were consistently observed in all population subgroups. CONCLUSION: It is estimated that 35% of the reported GI illnesses among the tapwater drinkers were water-related and preventable. Our results raise questions about the adequacy of current standards of drinking water quality to prevent water-borne endemic gastrointestinal illness.

Adolescent↗
PubMed1990

Interaction between norepinephrine and serotonin in the neuroendocrine control of growth hormone release in the rat.

Both alpha 2-adrenergic (alpha 2) and serotonergic (5HT) neurons are associated with stimulation of GH secretion via GRH release. The object of this study was to determine whether the 5HT system is involved in the stimulation of GH secretion by alpha 2-receptor agonists. There are two parts of this study. In the first, the relationship between alpha 2-5HT systems were analyzed by determining if alpha 2-stimulated GH release is mediated by 5HT. In this model, systemically administered alpha 2-agonists [clonidine (CLON) or UK14,304] were tested against 5HT antagonists (meterogoline or cyproheptadine) or 5HT synthesis inhibitors (p-chlorophenylalanine methylester hydrochloride). In the second, sites of 5HT-GRH interaction were determined by testing the response to CLON after 5HT neurotoxin [5,7-dihydroxytryptamine (5,7-DHT)] microinjection at specific hypothalamic nuclei. In both experiments sequential blood samples were withdrawn from silastic jugular cannulas in unanesthetized, freely moving animals. Metergoline (0.045 and 0.135 mg/kg, iv) and cyproheptadine (0.969 micrograms/kg, iv) suppressed, in a dose-dependent manner, the CLON (33 or 66 micrograms/kg, iv)-induced GH surge that was detected 15-30 min after injection in control animals. Both cyproheptadine (0.969 micrograms/kg, iv) and p-chlorophenylalanine (300 mg/kg, ip) effectively suppressed the UK14,304 (220 micrograms/kg, iv)-induced GH surge that occurred 15-30 min after injection in control animals. These data suggest that an intact 5HT system is required for alpha 2-stimulated GH release. 5,7-DHT neurotoxin microinjected into the midline arcuate nucleus (6 micrograms/mg,iv) or bilaterally into the ventromedial nucleus or perifornical area (4 micrograms/0.2 microliter) 5 days previously suppressed the CLON (30 micrograms/kg)-induced GH surge only in animals with arcurate nucleus lesions. To determine if the suppression was mediated by inhibition of GH-releasing hormone (GRH) or stimulation of somatostatin (SRIF), an additional experiment was conducted including 5,7-DHT arcuate nucleus-lesioned animals injected with anti-SRIF. Inasmuch as anti-SRIF failed to reverse the 5,7-DHT suppression of GH secretion, the results of this experiment suggest that GRH mediates NE-5HT-induced GH secretion. In conclusion, these data suggest that alpha 2 activation of GH secretion requires intact serotonergic terminals in the arcuate nucleus and most likely involves GRH rather than SRIF, release.

5,7-Dihydroxytryptamine↗
PubMed1979

Staining calcified tissues in plastic embedding medium.

Two procedures for staining sections of calcified teeth and/or bone embedded in plastic without dissolving the embedding medium were developed to study early bone regeneration in proximity to carbon implants in monkey alveolar bone and tissue degeneration in pathological human bone. These procedures allow differential staining of delicate bone tissues and prevent breakage of sections because the supporting plastic does not have to be removed.

Animals↗
PubMed1978

A modified processing and sectioning technique for hard tissues.

A new procedure for embedding and sectioning hard tissues was developed to study bone regeneration in relation to carbon implants used in crown and bridge preparations of maxillas and mandibles of nonhuman primates. Tissues were fixed in 10 percent neutral buffered formalin, dehydrated in 95 percent and 100 percent ethyl alcohol, and embedded in a modified Spurr's low-viscosity embedding medium. Tissues were sectioned as thin as 50 to 100 micron with a Buehler Isomet Model 11-1180 low speed saw. Unstained sections, as well as tissue stained with hematoxylin and eosin and Gomori's trichrome, were examined with a light microscope. The sections were of high quality without distortion. This new procedure expedited experimental work because decalcification of tissues was not needed and implants did not fragment.

Animals↗
PubMed1977

Automated high-resolution gas chromatographic analysis of psychotropic drugs in biological fluids using open-tubular glass capillary columns. I. Determination of nomifensine in human plasma.

An automated high-resolution gas chromatographic method has been developed for the determination of low levels of the antidepressant psychotropic drug Nomifensine in human plasma. The drug is extracted from alkalinized plasma with diethyl ether and then back-extracted into an acidic aqueous phase. After subsequent extraction into diethyl ether the drug is analysed by gas-liquid chromatography as its heptafluorobutyrate derivative using an OV-101 open-tubular glass capillary column with a nitrogen-specific detector. The propyl and butyl analogues of Nomifensine are used as internal standards, added to the plasma before extraction. The method is accurate, specific and precise, and capable of measuring plasma concentrations down to a level of 2 ng/ml. A preliminary study of the pharmacokinetics of the drug, together with steady-state level measurements in normal individuals receiving therapeutic dosages of Nomifensine, has been made.

Adult↗
PubMed1977

Knife sharpening revolutionized.

A new application has been found for an adhesive-backed, nylon polishing cloth previously used chiefly in the metallurgic field. When adhered to the glass plate of an automatic microtome knife sharpener, the cloth provides a superior sharpening surface and eliminates the need for resurfacing the plate. We have found this new technique simple, inexpensive, and timesaving.

Histology↗
PubMed1976

Mutual visual regard during mother-infant play.

Mutual visual regard was observed in 48 mother-infant dyads during a 6-min. play session. Infant-mother dyads containing 4 mo. -olds displayed significantly more mutual visual regard than dyads containing 6- or 8-mo.-olds. In addition, the more time infants spent in face-to-face interaction with mother, the more smiling they engaged in. No sex difference were observed.

Age Factors↗
PubMedDate not supplied

Investigating stroke.

Explore the source record for details and available documents.

Activities of Daily Living↗