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Biomedical subjects

K L Matthews

Publications and source records attributed to K L Matthews.

17 recordsLinked to original sources
PubMed2001

Excellent supervision: the residents' perspective.

Former residents rated their videotaped psychotherapy supervision sessions on how helpful their supervisors were as teachers during the session. Residents' and experts' ratings of the same videotape were compared and found to have no significant correlation. However, male residents were less critical than either female residents or experts. Former residents were also interviewed. Supervisors were rated as excellent when they were accepting and also when they provided guidance about highly charged clinical dilemmas. Discussion of the impact of the residents' personal experiences on the clinical encounter was also rated high and is best understood from an adult developmental perspective. The findings reveal the lasting value of sympathetic supervisors acknowledging personal concerns and are likely mirrored in all clinical settings.

Adult↗
PubMed1999

Pharmaceutical therapies for sealing of permeabilized cell membranes in electrical injuries.

Several years ago, we proposed that loss of cell membrane structural integrity by electroporation is a substantial cause of tissue necrosis in victims of electrical trauma. Specifically, this involves the permeabilization of the lipid bilayer by thermal and electrical forces. We further suggested that certain mild surfactants in low concentration could induce sealing of permeabilized lipid bilayers and salvage of cells that had not been extensively heat-damaged. Successful restoration of membrane transport properties using the surfactant poloxamer 188 was reported in 1992. The purpose of this study is to further examine the response of electroporated rat skeletal muscle membranes to poloxamer 188 (P188) therapy by direct assay of membrane transport properties. Experimental evidence accumulated to date suggests that P188 is effective in sealing permeabilized cell membranes both in vitro and in vivo.

Animals↗
PubMed1999

Release of endogenous ascorbic acid preserves extracellular dopamine in the mammalian retina.

PURPOSE: To investigate whether the inhibitory effect of nitric oxide (NO) on dopamine release from the retina is due to chemical oxidation of dopamine in the extracellular medium rather than to an inhibitory effect on dopamine release from retinal neurons. METHODS: Dopamine was incubated in Krebs bicarbonate medium and its rate of chemical degradation measured by high-performance liquid chromatography (HPLC). The effects of NO donors and antioxidants on dopamine were assessed by comparing dopamine degradation in the presence and absence of drug. The effects of NO donors on the K-evoked release of [3H]dopamine were measured from isolated superfused rabbit retinas. The release of ascorbic acid from the isolated rat retina and from an eyecup preparation in anesthetized rabbits was measured by HPLC. RESULTS: After 10 minutes' incubation in Krebs bicarbonate medium, the dopamine concentration decreased by 20%. This decline increased to 80% in the presence of S-nitroso-N-acetyl-DL-penicillamine (SNAP) or sodium nitroprusside (SNP). The increased rate of dopamine degradation was abolished if retina was incubated in the medium and then removed before the incubation of dopamine. The protective effect of preincubation with tissue was lost in the presence of ascorbate oxidase suggesting the release of ascorbic acid. HPLC analysis confirmed a substantial release of ascorbic acid from both rabbit and rat retinas. The K-evoked release of [3H]dopamine from the rabbit retina was inhibited by SNP. CONCLUSIONS: NO can rapidly, oxidize dopamine in physiological medium, but in the presence of retina, sufficient endogenous antioxidants (mainly ascorbate) are released to prevent this chemical reaction. Thus, the inhibitory action of NO on dopamine release results from an action on retinal neurons. Ascorbate release in the retina may have an important physiological role in prolonging the life of dopamine, which often has to diffuse long distances from axons in the inner plexiform layer to receptors in other retinal layers.

Animals↗
PubMed1998

Transformation of tooth type induced by inhibition of BMP signaling.

Mammalian dentitions are highly patterned, with different types of teeth positioned in different regions of the jaws. BMP4 is an early oral epithelial protein signal that directs odontogenic gene expression in mesenchyme cells of the developing mandibular arch. BMP4 was shown to inhibit expression of the homeobox gene Barx-1 and to restrict expression to the proximal, presumptive molar mesenchyme of mouse embryos at embryonic day 10. The inhibition of BMP signaling early in mandible development by the action of exogenous Noggin protein resulted in ectopic Barx-1 expression in the distal, presumptive incisor mesenchyme and a transformation of tooth identity from incisor to molar.

Animals↗
PubMed1994

A miniature gamma camera.

We have described a mobile miniature-gamma-camera system for use in electrical trauma units and have presented images and imaging characteristics of a prototype system. The system has as its principal component a miniature gamma camera based on a PSPMT. The camera is 92 mm x 92 mm x 190 mm in size, weighs 5 kg, has a 48 mm x 48 mm field of view, and has an intrinsic resolution of approximately 3 mm FWHM and 6 mm FWTM. It is expected that devices of this type will be useful as imaging tools in electrical trauma units and laboratories where imaging studies regarding uptake mechanisms of radiopharmaceuticals for assessing tissue viability are carried out.

Electric Injuries↗
PubMed1994

Qualities of adolescent mothers' parenting.

PURPOSE: This study examined the interrelations among adolescent mothers' parenting attitudes, parenting confidence, and parenting stress and the potential differences in these dimensions by mothers' age, race and parity, and age and sex of child. METHODS: Subjects were 119 former adolescent mothers (M age = 20.2 years) from predominantly poor, minority backgrounds (50% Hispanic, 27% African-American, 17% non-Hispanic white). All subjects completed questionnaires about their parenting qualities twice an average of 10 weeks apart. All children were at least one year of age (M age = 37.2 months; range 12-50 months). RESULTS: Results indicated that for some mothers there exists a triple jeopardy of low parenting confidence, high parenting stress, and inappropriate parenting values. Young maternal age at delivery and young maternal age at the time of this study were associated with low child acceptance. Non-Hispanic white mothers had significantly more favorable parenting values than did African-American and Hispanic mothers, and African-American mothers reported significantly greater caretaking confidence than did Hispanic mothers. No parity or sex of child effects were found. CONCLUSIONS: These results suggest the presence of meaningful patterns of convergence and within-group variation for the psychological qualities of adolescent mothers' parenting.

Adolescent↗
PubMed1993

What do excellent psychotherapy supervisors do?

OBJECTIVE: The author's goal was to discover strategies used by psychotherapy supervisors judged to be excellent teachers. METHOD: In an earlier study, experienced teachers of psychotherapy rated the level of excellence of 34 different supervisors in 53 videotaped supervision sessions. In this study, the authors examined the transcripts of the nine videotapes assigned the highest ratings as well as three videotapes assigned mid-level ratings and three videotapes assigned low ratings in the previous study. In analyzing these transcripts, the authors drew from their experience with the complete set of videotapes. RESULTS: Supervisors with high ratings allowed the resident's story about the encounter with the patient to develop. They consistently tracked the most immediate aspects of the resident's affectively charged concerns. Most of their comments were directed toward helping the resident further understand the patient and were specific to the material presented in the session. The resident was invited to speculate about the material, and technical words were used sparsely. Discussions about the relationships between resident and patient and between supervisor and resident were in the context of the resident's concerns. Supervisors with mid-level ratings were less disciplined in tracking the resident's concerns and inhibited the development of the resident's story. Supervisors with low ratings paid little or no attention to the resident's issues. CONCLUSIONS: The ability to track residents' concerns is at the center of supervisory activities rated as excellent. The resident provides data about what occurred, and new knowledge is constructed in the supervisory interaction. These findings provide an empirical basis for orienting supervisors to supervision.

Humans↗
PubMed1992

Quantitative assessment of the behavior of psychotherapy supervisors.

OBJECTIVE: The aim of this study was to explore the behavior of psychotherapy supervisors by using the Psychotherapy Supervision Inventory. METHOD: The authors used the Psychotherapy Supervision Inventory to rate 53 videotaped supervision sessions of 34 different supervisors. They also used the variable of the rater's perception of the excellence of the supervisor as a teacher. The data were subjected to a cluster analysis and a K-means analysis. Discriminant function analyses were applied to the comparison of the behavior of 19 supervisors with two different residents and the behavior of all 34 supervisors with residents in three different years of training. The relationship between rater-perceived excellence and Psychotherapy Supervision Inventory scores was analyzed by using stepwise multiple regression. RESULTS: There was a high level of agreement among the four raters' judgments of supervisors' excellence. Empathy accounted for 72% of the variance in rater-perceived excellence and focus on the therapist accounted for an additional 5%. When empathy was dropped from the equation, experiential orientation accounted for 60% of the variance in ratings of excellence, clarification and interpretation accounted for an additional 16%, and depth accounted for another 3%. CONCLUSIONS: In the context of established relationships, supervisors have stable behavior patterns. Rater-perceived excellence is related to the supervisor's focusing on the resident's immediate experiences and making many synthesizing comments in depth. The Psychotherapy Supervision Inventory can be used to orient supervisors to supervision and provide feedback about their behavior.

Cluster Analysis↗
PubMed1983

Combination of multiple-family therapy with parallel groups.

Parallel groups for children, adolescents, and parents have been a usual modality in the Community Guidance Center for over 12 years. This has provided effective therapeutic intervention. However, an inherent difficulty in these groups was discussion with parents about the identified patient's progress. Various methods, on a trial-and-error basis, were attempted. The most successful process, which evolved four years ago, is a multiple-family-therapy session combined with the parallel groups. The multiple-family-therapy group provides an interface for five subsystems [parents and children, also forming families; trainees; staff], opens communication to parents about the child's progress and includes the parent more viably in the treatment process. It provides greater awareness and opportunity for work toward family and individual goals with major focus on communication skills, role modeling for parents and trainees, and realistic goal setting.

Adult↗
PubMedDate not supplied

Activation of nicotinic receptors on GABAergic amacrine cells in the rabbit retina indirectly stimulates dopamine release.

The retina possesses subpopulations of amacrine cells, which utilize different transmitters, including acetylcholine (ACh), GABA, and dopamine. We have examined interactions between these neurones by studying the effects of nicotinic agonists on GABA and dopamine release. Isolated rabbit retinas were incubated with [3H]dopamine and then superfused. Fractions of the superfusate (2 min) were collected and the [3H]dopamine in each sample was measured. Endogenous GABA release was examined by incubating retinas in a small chamber. At 5-min intervals, the medium was changed and the GABA measured by high-pressure liquid chromatography (HPLC). Exposure of the retina to nicotine, epibatidine, and other nicotinic agonists increased the release of both GABA and dopamine. The effects of nicotine and epibatidine were blocked by mecamylamine, confirming an action on nicotinic receptors. The action of epibatidine on dopamine release was unaffected by glutamate antagonists but was blocked by picrotoxin and gabazine. These results suggested that nicotine might increase dopamine release indirectly by stimulating the release of GABA, which in turn inhibited the release of an inhibitory transmitter acting tonically on the dopaminergic amacrines. Exposure of the retina to GABA caused a small increase in dopamine release. This hypothetical inhibitory transmitter was not GABA, an opioid, adenosine, glycine, nociceptin, a cannabinoid, or nitric oxide because appropriate antagonists did not affect the resting release of dopamine. However, metergoline, a 5HT1/5HT2 receptor antagonist, and ketanserin, a 5HT2A receptor antagonist, but not the 5HT1A antagonist WAY100635, increased the resting release of dopamine and blocked the effects of nicotine. The 5HT1A/5HT7 agonist 8-hydroxy DPAT inhibited both the nicotine and GABA-evoked release of dopamine. We conclude that nicotinic agonists directly stimulate the release of GABA, but the evoked release of dopamine is indirect, and arises from GABA inhibiting the input of an inhibitory transmitter, which we tentatively identify as serotonin.

Animals↗
PubMedDate not supplied

The 1995 Lindberg Award. Nonthermally mediated muscle injury and necrosis in electrical trauma.

Joule heating has long been considered the principal component of tissue damage in electrical injury. Recent studies suggest electroporation, a nonthermally mediated mechanism of cell membrane damage, is also a factor. We investigated whether electroporation-mediated muscle necrosis can occur in vivo without significant Joule heating. Pulsed electric fields approximately 150 V/cm were produced in the hind limbs of anesthetized rats. In shocked limbs core muscle temperature rose less than 1.8 degrees C, yet significant damage occurred as determined by technetium-99m pyrophosphate uptake, elevated serum creatine phosphokinase, and prominent hypercontraction band degeneration of myofibers on histopathologic examination. This study is significant because it directly addresses whether nonthermal mechanisms of cell damage can cause tissue necrosis. These results indicate that electroporation effects can mediate skeletal muscle necrosis without visible thermal changes. Thus the phenomenon of "progressive recognition" may be characteristically largely explained by the occurrence of nonthermally mediated tissue damage.

Animals↗