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Biomedical subjects

S Collins

Publications and source records attributed to S Collins.

At least 235 records · Page 13Linked to original sources
PubMed1985

Use of the pill electrode for transesophageal atrial pacing.

The pill electrode, which was developed for esophageal electrocardiography, has found application in transesophageal atrial pacing during procedures such as conversion of tachycardia, electrophysiologic measurement, and acceleration of heart rate to produce stress during cardiac imaging studies. This paper presents theoretical studies that examine the relationship of interelectrode distance, current level, and pulse duration to the achievement of successful capture. Theoretical results agree with our clinical findings, i.e., current levels of 25 mA are effective to sustain capture; increased pulse duration reduces current requirements; and close bipolar spacing combines efficacy with safety. Results of animal studies performed to assess the extent of esophageal burn injury reveal that current levels in excess of 75 mA are required to produce lesions in short-term (under 30 minutes) pacing, and greater than 60 mA in long-term (4 hours) pacing. These results are based on experiments using a pulse duration of 2 ms, and the current levels that produce injury will be considerably lower if longer pulse durations are used. Typical current levels and pulse durations for successful capture are presented for 46 subjects in several new clinical applications. Termination of tachycardia, basic electrophysiologic measurements, and controlled acceleration of heart rate can be performed noninvasively with this technique.

Adolescent↗
PubMed1984

Human thoracic anatomy based on computed tomography for development of a totally implantable left ventricular assist system.

Human thoracic anatomy was studied using computed tomography (CT) for the development of a totally implantable electrohydraulic left ventricular system [Nimbus, Inc., and The Cleveland Clinic Foundation (CCF)]. To obtain statistical dimensional information for the chest wall, apex of the heart, and aorta, routine calibrated CT scans of 18 men and 17 women were analyzed. A special radiopaque vest was worn by the patient just prior to the scanning and X-ray procedures, so that each transverse scan could be assigned to a specific chest level after combination with a standard vertical referencing system set on the patient's radiogram. A polar coordinate system and direct measurement of transverse distances from the vertical column to points on the chest wall were employed to define collectively the shape and size of the intrathoracic surface of the chest wall. Locations of the aorta and apex were described by measuring their normalized distances from the midline and vertical column to the intrathoracic surface of the lateral and anterior chest wall. The radius of curvature of the intrathoracic wall lateral to the left ventricle was determined to be approximately 10.4 cm for the average adult male chest. The present CCF intrathoracic pump with this curvature fits fairly well in both the average and individual thoraxes of these adult males. The location of the aorta, particularly of the descending aorta, was used to determine the optimal outlet design. The most critical anatomical area was the apex location. For adult males, an average distance of 2.8 cm from the apex to the internal chest wall was found. Because of this small dimension, careful design of the inflow port is being performed to avoid anatomical mismatch.

Adult↗
PubMed1984

Carcinogen-binding proteins. High-affinity binding sites for benzo[a]pyrene in mouse liver distinct from the Ah receptor.

Mouse liver cytosol contains saturable, high-affinity binding sites for the aromatic carcinogen benzo[a]pyrene that are distinct from the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-binding aryl hydrocarbon receptor. Specific binding parameters determined by an equilibrium binding assay indicate a dissociation constant of 7.7 nM and a binding capacity of 4.7 pmol of benzo[a]pyrene per milligram of cytosolic protein. Although the data best fit a single class of binding sites by Scatchard and Hill analyses, discrete 4 S and 9 S [3H]benzo[a]pyrene peaks are identified on sucrose density gradients comprising about 98% and 2% of the specific binding, respectively. Steroid hormones and other ligands for previously described binding proteins have no effect on the specific carcinogen binding when present in the cytosol incubation at saturating levels. The glutathione S-transferases, shown in rat and human liver to possess carcinogen-binding properties, were also found not to be responsible for this receptor-like benzo[a]pyrene binding in mouse liver cytosol. Competition binding studies indicate that other aromatic hydrocarbon compounds of a structure similar to that of benzo[a]pyrene are equipotent in affinity for this major carcinogen-binding site.

Animals↗
PubMed1983

The effects of proglumide on cholecystokinin-, bombesin-, and glucagon-induced satiety in the rat.

Intraperitoneal (IP) administration of the glutaramic acid derivative proglumide inhibited satiety induced by all IP doses of cholecystokinin octapeptide (CCK-OP) in 3-hour food-deprived intact rats. Proglumide did not influence satiety when administered alone and did not inhibit satiety induced by IP glucagon. While proglumide did not inhibit satiety induced by low doses of IP bombesin, it partially and significantly inhibited the satiety effects produced by high doses of this peptide. Since bombesin is a known secretagogue for CCK in several species, these results indicate that while bombesin and CCK act independently to induce satiety, the effect induced by high doses of bombesin is mediated, in part, by the release of endogenous CCK or a structurally related peptide. Furthermore, these results illustrate that proglumide is a specific antagonist of CCK-induced satiety and is, therefore, a potentially useful tool for investigating the physiologic role of this peptide in the control of food intake.

Animals↗
PubMed1983

The treatment of obsessive-compulsive disorder in adolescence. A report of fifteen cases.

The treatment of 15 adolescents with obsessive-compulsive disorder is described. Treatment was in most cases primarily behavioural (response-prevention), with the family involved in the therapy. Other components of treatment which were used in some cases are also described: medication, psychotherapy, and 'milieu' therapy. Outcome after treatment was generally good, with symptoms in most cases being relieved entirely or reduced to a mildly incapacitating level. Treatment gains in most cases were maintained at follow-up. Obstacles to treatment are noted, and recommendations are made as to the management of the disorder in adolescence.

Adolescent↗
PubMed1982

SCAN: a method of community collaboration.

Recent research has highlighted the complexity of the battered child syndrome. Clinical experience suggests that treatment of troubled families is a long-term process, draining financial resources of agencies and emotional resources of professionals. The need to provide support and case consultation to professionals working in the area of child abuse and neglect evolved in the establishment, in 1968, of the Suspected Child Abuse and Neglect (SCAN) Program at Children's Hospital, Pittsburgh, Pennsylvania. This program provides an effective method of intervention through identification, consultation, referral and follow-up of at-risk families. Weekly meetings offer multi-disciplinary case coordination, treatment recommendations, and a channel of communication for representatives of community agencies. This paper traces the history and present status of the SCAN Program, as well as the role of SCAN as a force for change of community attitudes.

Child↗
PubMed1981

Familial thyroid hormone resistance.

Eight patients with thyroid hormone resistance were found in four generations of a kindred containing 19 members. Results of studies in this family are consistent with an autosomal dominant mode of inheritance for this disorder. The affected family members were clinically euthyroid but all had goiters and markedly increased serum thyroid hormone levels: thyroxine (T4) = 21.1 +/- 2.1 microgram/dl; triiodothyronine (T3) = 323 +/- 60 ng/dl; free T4 = 5.4 +/- 0.9 ng/dl; and free T3 = 1,134 +/- 356 pg/dl (mean +/- SD). Serum thyrotropin (TSH) levels were normal or slightly elevated in six patients and responded normally to the administration of thyrotropin-releasing hormone (TRH) and L-triiodothyronine. Two patients who had previously undergone subtotal thyroidectomy had elevated baseline serum TSH levels and exaggerated TSH responses to the administration of TRH suggesting subclinical hypothyroidism despite elevated total and free thyroid hormone levels. The absence of thyrotoxicosis and normal serum TSH levels despite elevated serum free T3 and T4 levels in the untreated members of this family are consistent with resistance of pituitary and peripheral tissues to the actions of thyroid hormones. In addition, the absence of hypothyroidism and normal responsiveness of serum TSH to TRH and L-triiodothyronine administration in untreated family members suggest that the thyroid has compensated for the hormone resistance by increased secretory activity under the control of pituitary TSH secretion.

Adolescent↗
PubMed1980

Radioimmunoassay of thyroxine in 10 microliters of serum, with use of aggregated antithyroxine antibodies.

We describe a sensitive radioimmunoassay for rapidly determining the concentration of thyroxine in 10 microL of human serum. Aggregated antithyroxine antibodies are used to separate bound and free hormone. This speeds the assay and economizes on reagents without loss of sensitivity, specificity, or precision. Results for normal subjects and patients with thyroid disease agree well with those obtained by other, well-established techniques.

Antibodies↗
PubMed1979

Characterization of the continuous, differentiating myeloid cell line (HL-60) from a patient with acute promyelocytic leukemia.

In a prelminary communication, we described the establishment of a continuous human myeloid cell line (HL-60). Here we report the detailed properties of this cell line and document its derivation from the peripheral blood leukocytes of a patient with acute promyelocytic leukemia. As characterized by light and electron microscopy, the predominant cell type in both the fresh and cultured sources is a neutrophilic promyelocyte with prominent nuclear/cytoplasmic asynchrony. Up to 10% of the cultured cells spontaneously differentiate beyond the promyelocyte stage, and the proportion of terminally differentiated cells is markedly enhanced by compounds known to stimulate differentiation of mouse (Friend) erythroleukemia cells. The HL-60 cells lack specific markers for lymphoid cells, but express surface receptors for Fc fragment and complement (C3), which have been associated with differentiated granulocytes. They exhibit phagocytic activity and responsiveness to a chemotactic stimulus commensurate with the proportion of mature cells. As characteristic of transformed cells, the HL-60 cells form colonies in semisolid medium and produce subcutaneous myeloid tumors (chloromas) in nude mice. A source of colony-stimulating activity stimulated the cloning efficiency in soft agar 5--30-fold. Despite adaptations to culture, the morphological phenotype and responsiveness to chemical induction of differentiation is essentially unchanged through at least 85 passages. Cytogenetic studies reveal aneuploidy. Metaphases with 44 chromosomes predominated in vivo and in early culture passages; however, clones with 45 or 46 chromosomes became predominant with continued passaging. The most consistent karyotypic abnormalities were the deletion of chromosomes 5, 8, and X and the addition of a marker resembling a D-group acrocentric and of a submetacentric marker, most likely an abnormal E-group chromosome. No DNA herpesvirus or RNA retrovirus was isolated in the fresh or cultured cells. The HL-60 cultured cell line provides a continuous source of human cells for studying the molecular events of myeloid differentiation and the effects of physiologic, pharmacologic, and virologic elements on this process.

Adult↗
PubMed1978

Attributional and behavioral changes following two behavior management interventions with hyperactive boys: a follow-up study.

In a 6-month follow-up study of 2 interventions with hyperactive boys, different patterns of improvement were observed for an intervention which focused on self-control and 1 which employed contingent social reinforcement. Of the 2 manipulations, self-control methods produced significantly stronger long-term benefits in terms of the child's increased perception of personal control over academic outcomes; social reinforcement, on the other hand, produced significantly stronger long-term benefits in terms of teacher ratings of hyperactivity or impulsivity (Conners Teacher Rating Scale). Both interventions produced stable changes in terms of decreased behavioral impulsivity as measured by qualitative error scores on the Porteus Mazes.

Achievement↗
PubMed1976

A quantitative description of normal AV nodal conduction curve in man.

The AV nodal conduction curve generated by the atrial extrastimulus technique has been described only qualitatively in man, making clinical comparison of known normal curves with those of suspected AV nodal dysfunction difficult. Also, the effects of physiological and pharmacological interventions have not been quantifiable. In 50 patients with normal AV conduction as defined by normal AH (less than 130 ms), normal AV nodal effective and functional refractory periods (less than 380 and less than 500 ms), and absence of demonstrable dual AV nodal pathways, we found that conduction curves (at sinus rhythm or longest paced cycle length) can be described by an exponential equation of the form delta = Ae-Bx. In this equation, delta is the increase in AV nodal conduction time of an extrastimulus compared to that of a regular beat and x is extrastimulus interval. The natural logarithm of this equation is linear in the semilogarithmic plane, thus permitting the constants A and B to be easily determined by a least-squares regression analysis with a hand calculator.

Adult↗
PubMed1976

The effect of high pressure on the hemolysis of red blood cells.

Investigations into the effects of pressure on the hypotonic hemolysis of human erythrocytes show that pressures up to 130 atm (1700 psi) do not potentiate the hemolysis as has previously been suggested. Furthermore, such pressures do not remove the protection against hypotonic hemolysis conferred by the presence of general anesthetics to more than a negligible extent.

Anesthetics↗
PubMed1975

Inhibition of Coccidioides immitis in vitro and enhancement of antiococcidiodial effects of amphotericin B by polymyxin B.

Growth of the spherule phase of Coccidioides immitis in liquid glucose-mineral salts medium was suppressed for 13 days by 5 to 10 mug of polymyxin B per ml. Inhibition of growth was also noted when filter paper disks containing polymyxin B were placed on the surface of arthrospore-seeded defined medium solidified with refined agar. The antibiotic evidently damaged the cytoplasmic membrane inasmuch as spherules suspended in distilled water containing 10 mug of polymyxin B per ml rapidly lost nucleotides. Leakage of nucleotides was prevented by 0.1 M Ca(2+). The anticoccidioidal activity of amphotericin B (0.02 to 0.08 mug/ml) was enhanced by 2.5 mug of polymyxin B per ml. Colistin (polymyxin E) methanesulfonate did not inhibit spherule growth at concentrations as high as 50 mug/ml. This may be because colistin, though structurally similar to polymyxin B, is not cationic because its gamma-amino groups are masked by methanesulfonate radicals.

Amphotericin B↗