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Biomedical subjects

D Wolfe

Publications and source records attributed to D Wolfe.

At least 73 records · Page 4Linked to original sources
PubMed1992

Poloxamer 188 improves neurologic outcome after hypothermic circulatory arrest.

Poloxamer 188, an amphipathic copolymer with cytoprotective properties, was investigated as a means of improving neurologic outcome after a prolonged period (150 minutes) of deep hypothermic circulatory arrest. Dogs were perfusion cooled and surface cooled to 10 degrees C, the heart was arrested for 150 minutes, and then the dogs were rewarmed and weaned from bypass. Seven dogs were treated with poloxamer 188 before and after deep hypothermic circulatory arrest. Six control dogs were treated with saline. Surviving dogs were evaluated for 1 week after deep hypothermic circulatory arrest for neurologic deficits or behavioral changes. Neurologic outcome was graded by the following system: grade 1, death within the observation period; grade 2, comatose; grade 3, holds head up; grade 4, sits up; grade 5, stands; grade 6, normal in both behavior and gait. There were no deaths in the seven poloxamer 188-treated animals versus three deaths in the six control dogs. Poloxamer 188-treated dogs also manifested significantly less neurologic dysfunction after deep hypothermic circulatory arrest than did the control group (p less than 0.003). This study shows that poloxamer 188 has a significant impact in improving neurologic outcome after exceptionally long periods of deep hypothermic circulatory arrest.

Animals↗
PubMed1992

HMB-45 reactivity in adrenal pheochromocytomas.

Melanoma-specific antibody (HMB-45) is highly specific for junctional nevi, malignant melanomas, and related lesions. Rarely have other benign or neoplastic tissues demonstrated positivity with the monoclonal antibody following purification. In the present study, four of 12 pheochromocytomas contained chief cells that reacted with HMB-45. We discuss the clinical and pathologic implications of this finding.

Adolescent↗
PubMed1991

Scar revision.

Different scar revision techniques are compared on similar scars, all on the same patient. Comparison of the final results is unique and interesting and provides insight into choosing the "optimal" technique for these procedures. Historical perspective is provided.

Adult↗
PubMed1991

Intracranial chordoma in a preadolescent. Case report.

Chordomas are rare tumors derived from notochord remnants occurring primarily in the sacrum, clivus, and cervical regions. Exceptionally, these tumors occur in children, though usually in the sacrum. Eight cases of clivus chordoma have been described in preteenagers. In this report, a clival chordoma with unusual radiologic features is described in an 11-year-old boy. The literature regarding this entity is reviewed.

Brain Neoplasms↗
PubMed1991

S100 protein-positive sustentacular cells in malignant and locally aggressive adrenal pheochromocytomas.

The absence or presence of S100-positive sustentacular cells has been previously shown to be correlated with benign and malignant pheochromocytomas and paragangliomas. We evaluated a total of 17 malignant and recurrent or locally aggressive adrenal pheochromocytomas for their quantity of sustentacular cells. An absence of sustentacular cells was demonstrated in the majority of malignant cases, while the locally aggressive or recurrent group usually contained an abundance of these cells. However, in one malignant case a constant moderate number of sustentacular cells in the primary site and in two sequential metastases was found. We conclude that the absence of sustentacular cells in pheochromocytomas may indicate a lesion with a greater potential for metastasis and that sustentacular cells, when they are present in a malignant pheochromocytoma, are an integral part of the tumor.

Adolescent↗
PubMed1990

Children's observations of violence: I. Critical issues in child development and intervention planning.

Children are often the unintended or indirect victims of wife abuse as witnesses of this violence in their family. Current research on these children and a conceptual framework to understand how this violence affects their development are outlined. The implications of this research are discussed in terms of several intervention strategies. The importance of primary prevention programs in school systems is stressed.

Canada↗
PubMed1989

Methodological considerations contributing to variability of the quadriceps H-reflex.

The clinical usefulness of the quadriceps H-reflex is limited because of the difficulty of elicitation and its inherent variability in amplitude. In the present study we attempted to identify the influence of methodological variables (head position and remote muscle contractions) on the amplitude of the H-reflex evoked in vastus medialis, vastus lateralis and rectus femoris from the right leg of 13 healthy adult subjects. Square wave stimuli (1-ms duration) were delivered percutaneously to the femoral nerve. The 50% maximal amplitude H-reflexes were evoked while the subject reclined with head facing to the right, left, up and down or while the subject performed Jendrassik's maneuver. The results show a significant increase in the reflex amplitude when the subject's head was turned to the right; there was either a mild increase or no change in amplitude of the response when the subjects faced to the left, up and down. The evoked potential tended to decrease when the subjects closed their eyes; however, the tendency to increase with neck position was not changed. Remote muscle contractions enhanced the amplitude of the response. These results present further evidence of the characteristics of the quadriceps H-reflex and identify postural influences as one controllable source of variability in the L3-L4 root electrodiagnostic test.

Adult↗
PubMed1987

Flow cytometric purification of Alzheimer's disease amyloid plaque core protein using thioflavin T.

Amyloid plaque core protein (APCP) of Alzheimer's disease obtained from brain tissue homogenate is difficult to recover in pure form, primarily because of contaminating lipofuscin (LF) granules. Thioflavin T, a fluorescent dye previously used to stain amyloid, was found to bind to APCP but not to lipofuscin. The latter, however, is autofluorescent. Fluorometric studies showed that at 370 nm excitation APCP has a maximal emission at 418 nm, whereas the autofluorescent LP has a maximal emission at 450 nm. This difference in emission permitted the use of a flow cytometer-sorter (FACS 440) for purification of APCP. APCP particles fluoresced distinctly from LF granules on the log blue fluorescence parameter. The two entities were sorted using forward light scatter versus fluorescence. A collection apparatus was designed and prepared to facilitate the collection of large volumes of sheath fluid and particles and to minimize fragmentation of particles during the collection process. The sorted APCP fraction was 98% pure. This work demonstrates how old dyes can be used to perform new tricks and provide a useful method for separating complex protein.

Alzheimer Disease↗
PubMed1986

Purification, ultrastructure, and chemical analysis of Alzheimer disease amyloid plaque core protein.

Isolation of Alzheimer disease amyloid plaque core protein (APCP) was carried out by repetitive NaDodSO4/EDTA/sucrose extractions and by Ficoll-400 density-gradient centrifugations. The enriched APCP-Ficoll interface was labeled with the fluorochrome thioflavin T and separated from the contaminating lipofuscin by fluorescence-activated cell sorting. Electron microscopy demonstrated that APCP is made of two different kinds of filaments measuring 5.5-6 nm and 10-12 nm, respectively, and of variable length. Purified APCP and lipofuscin were chemically modified by performic acid oxidation. The amino acid composition of APCP revealed a high content of glycine and valine (30%) and 1% cysteine. By contrast, the protein moiety of the copurified lipofuscin contained 16% cysteine. The amino acid composition of APCP did not resemble that of any known protein.

Alzheimer Disease↗
PubMed1986

Family violence and child adjustment: a comparative analysis of girls' and boys' behavioral symptoms.

The authors compared behavior problems and social competence in 126 boys and girls (age 6-11) from violent and nonviolent families, on the basis of maternal ratings on the Achenbach Child Behavior Checklist. Girls from violent families were reported as showing more internalizing behavior problems and a lower level of social competence than their nonviolent comparison group. Boys from violent families were reported as demonstrating both internalizing and externalizing behavior problems, in addition to having a lower level of social competence. For boys, the level of exposure to violence between parents was significantly associated with greater adjustment problems.

Adult↗
PubMed1984

Internal-external control and headache response to biofeedback and psychotherapy.

This study was undertaken to determine the comparative validity of two competing hypotheses derived from different conceptualizations of internal versus external control. On the basis of the premise that this dimension is merely a belief on the periphery of personality, it was predicted that headache patients who felt that they could exert some influence over their own health would become more involved in and hence derive more benefit from both psychotherapy and biofeedback than their counterparts who did not believe that their own efforts could affect their health status. Following the assumption that locus of control is a manifestation of an underlying need, however, it was predicted that externally oriented headache patients would respond more favorable to the structure provided by biofeedback than would their internally oriented counterparts, whereas internals would fare better than externals in the relatively less directive arena of psychotherapy. Although the results were mixed, they tend on balance to offer differential support for the interaction hypothesis and hence for the formulation of locus of control as a reflection of an underlying need rather than as a superficial belief.

Adult↗
PubMed1982

Teacher popularity and contrast effects in a classroom token economy.

There is a common fear that the use of a token economy in one classroom might harm pupil performance in situations where the contingencies are not in effect. This study investigated potential contrast effects on measures of children's productivity and attitudes toward teachers. Six children with reading deficits participated. A multiple baseline design was used to assess the effects of a token economy which was systematically introduced across three teachers. Dependent measures included two rating forms of teacher popularity and work rate on a programmed reading series. The results indicated that the token system was effective in increasing the children's productivity and that no consistent behavioral contrast effects occurred. Furthermore, children's attitudes toward teachers did not appear to be influenced by the token economy until only one teacher was not delivering tokens. At this point, her popularity declined until she also delivered tokens. The token economy manipulation appeared to have a specific, desirable effect on the targeted behavior (i.e., work rate) and had minimal negative or positive "side effects" on teacher popularity.

Attitude↗