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Biomedical subjects

L Swanson

Publications and source records attributed to L Swanson.

At least 37 records · Page 2Linked to original sources
PubMed1996

Absence of constitutive EGF receptor activation in ovarian cancer cell lines.

Previous investigators have noted that certain ovarian cancer cell lines secrete and respond to transforming growth factor-alpha (TGF-alpha), suggesting that endogenous activation of the epidermal growth factor (EGF) receptor through autocrine or paracrine mechanisms might contribute to the proliferative response. In order to determine whether autocrine stimulation was partly responsible for the proliferative response in ovarian cancer, we investigated whether the EGF receptor expressed by ovarian cancer cell lines was constitutively activated as assessed by the presence of tyrosine phosphorylation. A specific anti-phosphotyrosine antibody was used in conjunction with an immunoblotting technique in order to detect EGF receptor phosphorylation in ovarian cancer cell lines in the absence and presence of exogenous EGF. The effects of neutralising anti-EGF receptor antibody on the proliferation of ovarian cancer cell lines was also examined. We found no evidence for constitutive tyrosine phosphorylation of the p170 EGF receptor in eight epithelial ovarian cancer cell lines tested, although each line demonstrated inducible phosphorylation in response to exogenous EGF. The absence of constitutive EGF receptor activation was also noted when cells were grown under high density conditions, thus excluding a role for membrane-bound EGF or TGF-alpha in this process. Media conditioned by five ovarian cancer cell lines, as well as malignant ascites obtained from 12 different ovarian cancer patients, were not capable of stimulating EGF receptor phosphorylation. Finally, the proliferation of ovarian cancer cell lines was not significantly inhibited in the presence of neutralising anti-EGF receptor antibody. These data suggest that EGF receptor activation through autocrine pathways is not a major mechanism for the growth of many ovarian cancer cell lines. Other pathways of signal transduction which bypass the requirement for EGF receptor activation may be important in the proliferation for ovarian cancer cells. Such EGF receptor-independent pathways may limit the effectiveness of strategies designed to inhibit ovarian cancer cell growth through disruption of EGF receptor function.

Antibodies↗
PubMed1995

CD44 variant expression is a common feature of epithelial ovarian cancer: lack of association with standard prognostic factors.

PURPOSE: CD44 is a hyaluronic acid receptor that exists as a standard 90-kd form (CD44S) as well as several CD44 variant isoforms produced through alternative splicing. Expression of CD44 variants is associated with clinically aggressive behavior in some human tumors. The purpose of the present study is to define the expression of CD44 variant isoforms in ovarian cancer and to investigate whether the expression of these molecules is associated with adverse prognosis. MATERIALS AND METHODS: Six specimens of normal ovarian surface epithelium (NOSE) and 31 separate cases of newly diagnosed ovarian cancer were studied by a combination of reverse-transcription polymerase chain reaction (RT-PCR) and immunoperoxidase staining. Clinical correlation was made between CD44 variant expression and stage (I/II v III/IV), residual disease (< or = 2.0- v > 2.0-cm mass), age (< or = 65 v > 65 years), histology (papillary serous v other), grade, and survival. RESULTS: RT-PCR analysis revealed that NOSE predominantly expressed transcripts for CD44S, as well as a restricted pattern of transcripts characteristic of CD44 splice variants. CD44S and CD44 variant exon nine sequences (CD44-9v) were focally expressed in one of two NOSE specimens examined by immunoperoxidase staining. In comparison, the majority (71%) of ovarian cancer specimens expressed a complex pattern of CD44 splice variants by RT-PCR analysis. Immunoperoxidase studies revealed that the majority of ovarian cancer specimens expressed both CD44S and CD44-9v, whereas expression of sequences from variant exons 3, 4, and 6 was uncommon. There was no association between CD44 variant expression (transcript or protein) and stage, residual disease, age, histology, grade, or survival. CONCLUSION: Expression of CD44S and CD44-9v is a common feature of epithelial ovarian cancer cells. The lack of a significant association between CD44 variant expression and prognosis suggests that other factors may be more important in determining the clinical behavior of this disease.

Adenocarcinoma, Clear Cell↗
PubMed1993

Living with renal failure.

UNLABELLED: In this interpretive study, the experience of patients living with chronic renal failure was studied. Within the framework of Heideggerian phenomenology, a hermeneutic analysis revealed three themes and one constitutive pattern. The three themes were: taking on a new understanding of Being, maintaining hope and dwelling in dialysis. The constitutive pattern was " CONTROL: The Meaning of Technology." The findings provide an understanding of living with renal failure that argues against the traditional understanding of noncompliant behaviors. The study makes visible the meaning of technology in the lives of renal patients and highlights the need for nurses to sustain meaningful human connections with patients.

Adaptation, Psychological↗
PubMed1991

Pharmacokinetics, safety, and ability to diminish leukotriene synthesis by zileuton, an inhibitor of 5-lipoxygenase.

Zileuton is a potent and specific inhibitor of 5-lipoxygenase, the first dedicated enzyme in the metabolism of arachidonic acid to the leukotrienes. The leukotrienes have been implicated in numerous pathological conditions. Zileuton was given to normal human volunteers in single doses of 200 mg to 800 mg. Results of these studies indicated that zileuton was well absorbed orally with an elimination half-life of approximately 2.5 hours. Leukotriene B4 production by ex vivo calcium ionophone stimulated whole blood was inhibited by up to 80% of baseline and correlated with plasma concentrations. Zileuton did not significantly inhibit cyclooxygenase as demonstrated by thromboxane B2 levels. There were no safety concerns that would preclude development.

Adolescent↗
PubMed1988

A tissue-specific transcription factor containing a homeodomain specifies a pituitary phenotype.

Multiple related cis-active elements required for cell-specific activation of the rat prolactin gene appear to bind a pituitary-specific positive transcription factor(s), referred to as Pit-1. DNA complementary to Pit-1 mRNA, cloned on the basis of specific binding to AT-rich cell-specific elements in the rat prolactin and growth hormone genes, encodes a 33 kd protein with significant similarity at its carboxyl terminus to the homeodomains encoded by Drosophila developmental genes. Pit-1 mRNA is expressed exclusively in the anterior pituitary gland in both somatotroph and lactotroph cell types, which produce growth hormone and prolactin, respectively. Pit-1 expression in heterologous cells (HeLa) selectively activates prolactin and growth hormone fusion gene expression, suggesting that Pit-1 is sufficient to confer a characteristic pituitary phenotype. The structure of Pit-1 and its recognition elements suggests that metazoan tissue phenotype is controlled by a family of transcription factors that bind to related cis-active elements and contain several highly conserved domains.

Amino Acid Sequence↗
PubMed1986

Coexistence of tyrosine hydroxylase and growth hormone-releasing factor in a subpopulation of tubero-infundibular neurons of the rat.

The distribution of growth hormone-releasing factor (GRF) and tyrosine hydroxylase (TH), a marker for dopamine neurons in this region, was analyzed in the mediobasal hypothalamus with indirect immunofluorescence histochemistry and an elution-restaining procedure. TH-like immunoreactivity was present in most GRF-immunoreactive cells in the ventral part of the arcuate nucleus (ventral A12 dopamine cell group). Dopamine cells in the dorsal A12 group and, for example, in the hypothalamic A14 cell group seemed to lack GRF peptide. Partly overlapping GRF- and TH-immunoreactive fibers in the median eminence were observed, indicating possible coexistence of the two compounds also in nerve endings close to portal vessels. These findings suggest that a subpopulation of A12 dopamine neurons produces, stores and releases a GRF-like peptide. Possible interactions of GRF and dopamine in the control of growth hormone secretion are discussed.

Animals↗
PubMed1985

Therapeutic perspectives on father-daughter incest.

In recent years it has become apparent that father-daughter incest is not an uncommon occurrence. Many social forces have conspired to maintain secrecy at both the family and societal levels. The authors examine the evolution of professional attitudes and understandings of incest, beginning with Freud's writings on the subject, and offer specific recommendations for clinicians working with incest victims and their families.

Adolescent↗
PubMed1985

Telemetric electromyographic analysis of muscle transferred to the os calcis.

Fifteen inphase muscle transfers to the os calcis from 11 patients with lower motor neuron paralysis were evaluated by means of telemetric electromyography during ambulation. In five of the limbs thus evaluated, electromyographic activity was found to resemble that of the normal triceps surae and had relatively normal proximal muscles. In ten limbs, contraction of the transferred muscle preceded heel strike. This was attributed primarily to proximal muscle weakness, which necessitated premature firing to ensure early knee extension during stance and hence to prevent the knee from buckling during weight-bearing.

Adolescent↗
PubMed1984

Warfarin dosage following prosthetic valve replacement: effect of smoking history.

Warfarin currently is the most widely used agent in the prevention of thrombosis and embolism after prosthetic cardiac valve replacement. Since smoking has been shown to increase the requirement for medications undergoing hepatic metabolism, this study was designed to determine if a correlation exists between smoking history and warfarin daily maintenance dose (DMD) in patients undergoing cardiac valve replacement. Of 200 charts retrospectively reviewed at the New England Medical Center, 174 satisfied the criteria for inclusion in the study (normal hepatic, renal, and hematologic function, and absence of complicating medications). The study population included aortic, mitral, and combined valve replacement. Study groups consisted of 117 nonsmokers (Group A), 23 light smokers (Group B), and 34 heavy smokers (Group C). Thirty-three percent of patients required a low DMD of warfarin (less than or equal to 2.5 mg), 43 percent required a moderate DMD (greater than 2.5-7.5 mg), and 24 percent required a high DMD (greater than 7.5 mg). Each of the subgroups followed a similar pattern. In Group A, there were 31 percent low, 44 percent moderate, and 25 percent high-dose requiring patients. In Group B, there were 48 percent low, 39 percent moderate, and 13 percent high-dose requiring patients and in Group C there were 29.5 percent low, 41 percent moderate, and 29.5 percent high-dose requiring patients. Chi-square analysis did not demonstrate any statistically significant difference between smokers and nonsmokers in regard to daily maintenance warfarin dose (p = 0.5). The study population followed a normal pattern of distribution in regard to warfarin dosage. On the basis of these data we conclude that smoking history does not affect warfarin dose requirement.

Adult↗
PubMed1983

The effect of different agars, agaroses and methyl cellulose on the in vitro proliferation of a human urinary transitional cell carcinoma cell line.

The effects of different agars (Bacto-agar and deoxycholate lactose agar), agaroses (LE, ME, Sea Plaque and Sea Prep 15/45) and methyl cellulose on the growth of a human tumor cell line, derived from a transitional cell carcinoma of the urinary bladder, were examined. The overall growth in the presence of agars and agarose was generally less than in liquid medium alone. In contrast, growth in the presence of methyl cellulose was significantly enhanced. Thus, methyl cellulose may be a useful agent for optimizing the proliferation of primary tissue cultures prepared from human transitional cell carcinomas.

Agar↗
PubMed1983

Effects of rehearsal activity and level of word processing on learning disabled and normal readers' free recall.

This study investigated the relationship of stimulus encoding and rehearsal activity in accounting for learning disabled readers' deficient recall performance. Learning disabled and nondisabled readers from ages 8 and 10.6 were compared on free recall of semantically and phonemically related words under two types of rehearsal conditions, one-item and multiitem repetitions. Consistent with previous work, developmental differences occurred in word recall with semantically related word lists being recalled more often than phonemically related ones. Regardless of age and rehearsal activity, learning disabled readers were inferior in recall to nondisabled readers. For both reading groups, the influence of the type of processing and rehearsal activity were not independent. That is, an interaction occurred between level of processing and rehearsal activity. The results were construed as evidence for deficient elaborative rehearsal and semantic encoding in learning disabled readers.

Age Factors↗