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Biomedical subjects

D Spicer

Publications and source records attributed to D Spicer.

At least 19 recordsLinked to original sources
PubMed2001

Application of tissue Doppler to interpretation of dobutamine echocardiography and comparison with quantitative coronary angiography.

The main limitation of dobutamine echocardiography (DE) is its subjective interpretation. We sought to reduce the need for expert interpretation by developing a quantitative approach to DE using myocardial Doppler velocity (MDV) in 242 patients undergoing DE. In 128 patients with a normal dobutamine echocardiogram, the normal range was designed to give a specificity of 80%. The accuracy of this range was investigated in 114 consecutive patients who underwent coronary angiography within 2 months of DE. A standard dobutamine echocardiographic protocol was used, with MDV gathered from color tissue Doppler at rest and peak stress. Wall motion at these stages was scored by experienced observers using a 16-segment model and MDV was measured off-line. Sensitivity and specificity of wall motion scoring and MDV were obtained by comparison with angiographic evidence of disease, defined as stenosis > 50% of the coronary artery diameter. The normal range in tethered segments (septum, anteroseptum, and inferior) was > or = 7 cm/s in the basal segments and > or = 5 cm/s in the midsegments. In the free wall (anterior, lateral, and posterior), the cutoff was > or = 6 cm/s in the base and > or = 4 cm/s in the midventricle. Of 114 patients undergoing angiography, 84 (75%) had significant stenoses, and the sensitivity of wall motion scoring and MDV were 88% and 83%, respectively, with specificities of 81% and 72% (p = NS). The accuracy was similar overall (86% vs 80%), as well as in each vascular territory. These data suggest that a fully quantitative interpretation of DE using site-specific normal ranges of tissue Doppler, which account for regional variations of base-apex function, is feasible and equivalent in accuracy to expert wall motion scoring.

Adult↗
PubMed2000

Preoperative paclitaxel and radiotherapy for locally advanced breast cancer: surgical aspects.

INTRODUCTION: Approximately 15% of breast cancer patients present with large tumors that involve the skin, the chest wall, or the regional lymph nodes. Multimodality therapy is required, to provide the best chance for long-term survival. We have developed a regimen of paclitaxel, with concomitant radiation, as a primary therapy in patients with locally advanced breast cancer. METHODS: Eligible patients had locally advanced breast cancer (stage IIB or III). After obtaining informed consent, patients received paclitaxel (30 mg/m2 during 1 hour) twice per week for 8 weeks and radiotherapy to 45 Gy (25 fractions, at 180 cGy/fraction, to the breast and regional nodes). Patients then underwent modified radical mastectomy followed by postoperative polychemotherapy. RESULTS: Twenty-nine patients were enrolled. Of these, 28 were assessable for clinical response and toxicity, and 27 were assessable for pathological response. Objective clinical response was achieved in 89%. At the time of surgery, 33% had no or minimal microscopic residual disease. Chemoradiation-related acute toxicity was limited; however, surgical complications occurred in 41% of patients. CONCLUSIONS: Preoperative paclitaxel with radiotherapy is well tolerated and provides significant pathological response, in up to 33% of patients with locally advanced breast cancer, but with a significant postoperative morbidity rate.

Adult↗
PubMed2000

Three-dimensional echocardiography: research toy or clinical tool?

Conventional 2D echocardiography is an excellent qualitative imaging method, but its use for quantitation is limited by test-retest reproducibility of image planes. The increasing sophistication of medical treatments for left ventricular dysfunction, hypertension and valvular heart disease has created the need for accurate and reproducible measurements of chamber dimensions. Similarly, improvements in valve repair and catheter-based interventions for valve lesions and septal defects have created the need for better visualisation of cardiac structures. The use of 31) echocardiography may decrease variability both in the quality and interpretation of complex pathology among investigators. Three-dimensional echocardiography is achieved by using a 3D spatial registration device with a conventional 21) scanner, or by using a high-speed, phased-array real-time scanner. The latter are still developmental, so that the technique currently requires use of a 21) scanner, combined with a 31) spatial coordinate system, which may be external or internal to the scanning transducer. An external system permits data acquired from several cardiac windows to be integrated and reconstructed. Image reconstruction is performed using a wire-frame model or surface rendering. Wire-frame models are formed by manual or automatic connection of boundary data points; this approach uses fewer data points than rendering, can be rapidly processed and is sufficient for quantitative analysis. Surface-rendering uses lighting and shading applied to a wire-frame model to produce a realistic 31) display, which may be useful for surgical planning and increasing understanding of anatomic relations. Three-dimensional echocardiography yields more accurate measurements of ventricular volume and function, as well as new measurements such as infarct area. With increased reproducibility and reliability, 3D echocardiography may well prove to be the essential tool required for the serial follow up of left ventricular mass and volume.

Journal Article↗
PubMed2000

Pharmacokinetic and pharmacodynamic evaluation of the glycinamide ribonucleotide formyltransferase inhibitor AG2034.

Glycinamide ribonucleotide formyltransferase (GARFT) is a component of the de novo purine synthesis pathway. AG2034 is a specific inhibitor of GARFT that was designed based on the GARFT crystal structure. In conjunction with Phase I studies at four clinical centers in the United States and United Kingdom, AG2034 pharmacology was evaluated in 54 patients receiving 1-11 mg/m2 AG2034 as a 2-5 min injection. Blood samples were obtained just prior to and 5, 15, 30, and 45 min, and 1, 1.5, 2, 4, 6, 8, 12, 24, 48, 72, and 96 h after bolus injection during course 1. Limited sampling was also performed on course 3. Plasma AG2034 was measured using a sensitive and reproducible ELISA assay. AG2034 demonstrated a trimodal elimination pattern over 24 h, with median half-life (t(1/2))alpha = 8.7 min, t(1/2)beta = 72.6 min, and t(1/2)gamma = 364.2 min. AG2034 systemic clearance ranged from 9.4-144.5 ml/min/m2, and volume of distribution was 1.2-7.6 liters/m2. Course 1 AG2034 area under the concentration versus time curve (AUC) had a linear relationship with dose (r(s) = 0.86). Accumulation of AG2034 was evident, because course 3 AUC was higher than course 1 in 23 of 23 evaluable patients, but was not associated with an increase in erythrocyte AG2034. AG2034 systemic exposure had an impact on toxicity, because course 1 and course 3 AG2034 AUCs were significantly higher for patients with grade III/IV toxicity than patients with less than grade II toxicity (P < 0.001 and P = 0.001 for course 1 and course 3, respectively). This study demonstrates rapid systemic clearance of AG2034 and suggests pharmacokinetic approaches that may minimize patient toxicity and aid the development of this interesting class of anticancer agents.

Adult↗
PubMed1999

Concurrent paclitaxel and radiation therapy for breast cancer.

Few studies have evaluated the role of concurrent chemoradiation therapy in the management of locally advanced breast cancer. The availability of radiosensitizing chemotherapeutic agents that are effective in breast cancer and the encouraging results achieved by concurrent chemoradiation in other malignancies have prompted us to investigate this approach. Paclitaxel is a promising agent for use with concurrent radiotherapy because of its single-agent efficacy profile and its radiosensitizing effects. A clinical protocol of preoperative paclitaxel and radiation in locally advanced breast cancer is ongoing at our institution to test feasibility, measure pathologic response at mastectomy, and explore association of pathologic response with molecular tumor markers. Initially, the study was designed to test weekly paclitaxel at a dose of 60 mg/m2 during radiation therapy, delivered 5 days a week at 200 cGy fractions to a total dose of 50 Gy over 5 weeks. Due to severe skin toxicity in the first two patients, the protocol was amended to change the scheduling of paclitaxel to 30 mg/m2 twice weekly and to reduce the radiation to 180 cGy fractions to a total dose of 45 Gy, delivered 5 days a week over 5 weeks. Presently, 13 patients have been accrued; preliminary data indicate good tolerance to twice-weekly paclitaxel, and four of eight evaluable patients have achieved pathologic response (one patient who received the weekly regimen and three who received the twice-weekly regimen). In addition, sequential fine-needle aspirations of palpable breast cancers were obtained in patients enrolled in a parallel study of preoperative single-agent paclitaxel (200 mg/m2 every 2 weeks, for a total of four cycles before breast surgery). Preliminary results suggest that a steep increase in the mitotic index occurs during the first day after paclitaxel administration and plateaus between the second and the third day, then decreases to pretreatment values. The peak apoptotic index occurs at approximately 72 hours after paclitaxel administration and decreases at approximately 98 hours. These initial findings suggest that twice-weekly dosing of paclitaxel may optimize recruitment of cells into the G2/M phase of the cell cycle, the most radiosensitive phase.

Antineoplastic Agents, Phytogenic↗
PubMed1998

Rabbit urethral regeneration using small intestinal submucosa onlay grafts.

OBJECTIVES: To determine if small intestinal submucosa (SIS) can evoke urethral regeneration. METHODS: Twenty male white New Zealand rabbits were assigned to one of three experimental groups. Group 1 (n = 4) underwent simple urethrotomy and closure. Group 2 (n = 8), a second control group, underwent an onlay urethroplasty with a graft of full-thickness preputial skin from the host rabbit. Group 3 (n = 8) underwent an onlay urethroplasty with an SIS graft. RESULTS: All eight SIS onlay grafts promoted regeneration of the normal rabbit epithelium supported by a well-vascularized collagen and smooth muscle backing. Preputial free onlay grafts maintained a keratinizing squamous cell epithelium with a poor supportive backing, which resulted in the formation of urethral diverticulum. CONCLUSIONS: SIS onlay patch grafts for urethroplasty promote rabbit urethral regeneration.

Animals↗
PubMed1998

Rat mesangial cells express two unique isoforms of laminin which modulate mesangial cell phenotype.

Rat mesangial cells express two unique isoforms of laminin which can be modulated by culture medium composition. To define further the nature of laminin expressed by cultured rat mesangial cells, synthesis of individual laminin chains, as well as their trimeric association, was examined. Based on data from Northern analysis of mRNA expression, immunoblots, immunofluorescence staining and radioimmunoprecipitation of biosynthetically labeled proteins, mesangial cells express laminin beta1, beta2, and gamma1 chains. Mesangial cells do not express laminin alpha1 or alpha2. MC produce a unique alpha chain, designated alpha'm. These laminin chains assemble into two major isoforms. One contains alpha'mbeta1gamma1, co-precipitates with entactin and is assembled into the fibrillar extracellular matrix. The second isoform contains alpha'mbeta2 and a presumed gamma chain that migrates in gel slightly ahead of gamma1. The beta2-containing isoform is concentrated in punctate sites on the cell surface. In addition, mesangial cells display different phenotypes when plated on laminin-1 (alpha1beta1gamma1), as compared to purified beta2. An LRE-containing peptide of laminin beta2 serves as an attachment site for mesangial cells and is sufficient to induce the phenotype observed with intact beta2. These data suggest that laminin isoform expression plays an important role in mesangial cell phenotype and function.

Animals↗
PubMed1997

Original p53 status predicts for pathological response in locally advanced breast cancer patients treated preoperatively with continuous infusion 5-fluorouracil and radiation therapy.

PURPOSE/OBJECTIVE: 1) To test feasibility of preoperative continuous infusion (c.i.) 5-Fluorouracil (5-FU) and radiation (RT) in locally advanced breast cancer. 2) To study clinical and pathological response rates of 5-FU and radiation. 3) To attempt preliminary correlations between biological probes and pathological response. METHODS AND MATERIALS: Previously untreated, locally advanced breast cancer patients were eligible: only patients who presented with T3/T4 tumors that could not be resected with primary wound closure were eligible, while inflammatory breast cancer patients were excluded. The protocol consisted of preoperative c.i. infusion 5-FU, 200 mg/m2/day with radiotherapy, 50 Gy at 2 Gy fractions to the breast and regional nodes. At mastectomy, pathological findings were classified based on persistence of invasive cancer: pathological complete response (pCR) = no residual invasive cells in the breast and axillary contents; pathological partial response (pPR) = presence of microscopic foci of invasive cells in either the breast or nodal specimens; no pathological response (pNR) = pathological persistence of tumor. For each patient pretreatment breast cancer biopsies were analyzed by immunohistochemistry for nuclear grade, ER/PR hormonal receptors, her2/neu and p53 overexpression. RESULTS: Thirty-five women have completed the protocol and are available for analysis. 5-FU was interrupted during radiation in 10 of 35 patients because of oral mucositis in 8 patients, cellulitis in 1, and patient choice in another. Objective clinical response rate before mastectomy was 71% (25 of 35 patients): 4 CR, 21 PR. However, in all 35 patients tumor response was sufficient to make them resectable with primary wound closure. Accordingly, all patients underwent modified radical mastectomy: primary wound closure was achieved in all patients. At mastectomy there were 7 pCR (20%), 5 pPR (14%) and the remaining 23 patients (66%) had pathological persistence of cancer (pNR). Variables analyzed as potential predictors for pathological response (pPR and pCR) were: initial TNM clinical stage, clinical response, nuclear grade, hormonal receptor status, p53 overexpression, and Her2/neu overexpression in the pretreatment tumor biopsy. Only initial p53 status (lack of overexpression at immunohistochemistry) significantly correlated with achievement of a pathological response to this regimen (p = 0.010). CONCLUSION: The combination of c.i. 5-FU and radiation was well tolerated and generated objective clinical responses in 71% of the patients. With the limitation of the small sample size, the complete pathological response achieved (20%) compares favorably with that reported in other series of neoadjuvant therapy for similar stage breast cancer. These preliminary data suggest that initial p53 status predicts for pathological response (pPR and pCR) to the combination of c.i. 5-FU and radiotherapy in locally advanced breast cancer.

Adult↗
PubMed1997

Preoperative 5-fluorouracil and radiation therapy for locally advanced breast cancer.

BACKGROUND: Fifteen percent of breast cancer patients present with large tumors involving skin or chest wall. Often, surgery with primary wound closure is impossible. We used neoadjuvant chemoradiation in locally advanced breast cancer patients, in hopes of increasing resectability. METHODS: Eligible patients had locally advanced breast cancer deemed unresectable with primary wound closure. Patients received 8 weeks of infusional 5-fluorouracil (5-FU) 200 mg/m2 per day and radiation therapy to 50 Gy. Patients rendered resectable underwent modified radical mastectomy (MRM) followed up by chemotherapy. RESULTS: Of 30 evaluable patients, 73% had an objective clinical response. All were able to undergo MRM with primary wound closure; 63% had residual disease, 20% had minimal microscopic disease, and 17% had complete pathologic response. Treatment-related toxicity was minimal. Surgical morbidity was not increased. CONCLUSIONS: Infusional 5-FU with concomitant radiotherapy is well tolerated and effective at producing shrinkage in the majority of patients, converting inoperable breast cancer to easily resectable disease.

Adult↗
PubMed1997

Insulin-like growth factor I (IGF-I) induces unique effects in the cytoskeleton of cultured rat glomerular mesangial cells.

Resident glomerular mesangial cells (MCs) have complex cytoskeletal organizations that maintain functional and structural integrity. The ability of cells to replicate, coordinate movement, change shape, and interact with contiguous cells or extracellular matrix depends on cytoskeletal organization. MCs synthesize insulin-like growth factor (IGF-I), express IGF-I receptors, and respond to IGF-I with increased proliferation. We noted that IGF-I treatment of mesangial cells was associated with a change in morphology. Therefore, these studies were undertaken to define specific IGF-I-mediated changes in cytoskeletal protein organization. Rat MCs were propagated from birth in culture without supplemental insulin. Quiescent, subconfluent cultures were treated with IGF-I (100 nM) for 1 hr. Rearrangements in f-actin, alpha-smooth muscle actin, beta-actin, vimentin, and vinculin were seen by fluorescence microscopy. As the cytoskeleton rearranged, alpha-smooth muscle actin dissociated from the f-actin bundles and beta-actin became polymerized under the leading lamellar edge. Ultrastructural changes were consistent with increased membrane turnover and metabolic activity. The normally sessile mesangial cell was induced by IGF-I to express a wound-healing phenotype characterized by movement and increased pinocytosis. These changes are different from those induced by insulin and have important implications for mesangial cell function.

Animals↗
PubMed1997

Cardioprotection with dexrazoxane for doxorubicin-containing therapy in advanced breast cancer.

PURPOSE: To determine the cardioprotective effect of dexrazoxane (DZR) used in a doxorubicin-based combination therapy in advanced breast cancer. PATIENTS AND METHODS: Between November 1988 and January 1991, 534 patients with advanced breast cancer were randomized to two multicenter, double-blind studies (088001 and 088006). Patients received fluorouracil, doxorubicin, and cyclophosphamide (FAC) with either DZR (DZR-to-doxorubicin ratio, 10:1) or placebo (PLA) every 3 weeks and were monitored with serial multiplegated acquisition (MUGA) scans. RESULTS: The hazards ratio (HR) of PLA to DZR for a cardiac event, which was predefined ejection fraction changes or congestive heart failure (CHF), was 2.63 (95% confidence interval [CI], 1.61 to 4.27; P < .001) for 088001 and 2.00 (95% CI, 1.01 to 3.96; P = .038) for 088006. The objective response rates for 088001 were 46.8% for DZR and 60.5% for PLA, a difference of 14% (95% CI, -25% to -2%; P = .019), and for 088006 were 53.7% for DZR and 49.3% for PLA, a difference of 4% (95% CI, -13% to 22%; P = .63). Time to progression and survival were not significantly different between treatment arms in either study. Toxicities on the DZR arms included lower granulocyte and platelet counts at nadir (P = .009 and P = .004, respectively) and more pain on injection (P = .001), with no difference in the rates of fever, infection, or hemorrhage. CONCLUSION: DZR had a significant cardioprotective effect as measured by noninvasive testing and clinical CHF. One of the two studies (088001) showed a lower response rate with DZR, but time to progression and survival were not significantly different. DZR is the first agent shown to reduce cardiotoxicity from doxorubicin.

Aged↗
PubMed1997

Diabetes induces changes in glomerular development and laminin-beta 2 (s-laminin) expression.

Offspring of diabetic mothers have developmental renal abnormalities; thus, we investigated the effects of the diabetic milieu on kidney development. Four groups of host rats, including insulin-deficient and insulin-treated streptozotocin-induced diabetic rats, normal controls, and insulin-treated nondiabetic rats, were prepared. After 38 days, rats received ocular implants of E14 fetal rat kidneys. Nine days later the fetal kidney grafts were harvested for analysis of glomerular development and expression of fibronectin, laminin, laminin-beta 2, and alpha-smooth muscle actin and m170, two additional markers of mesangial maturation. The rate of glomerular maturation was delayed in grafts placed in hyperglycemic, insulin-deficient diabetic rats. These glomeruli contained few mesangial cells or matrix, and laminin-beta 2 expression was reduced as compared with controls. Mesangial expression of alpha-smooth muscle actin and m170 was not detected. In contrast, grafts placed in insulin-treated diabetic animals had increased numbers of mesangial cells and expanded mesangial matrix. The content of laminin-beta 2 and expression of m170 and alpha-smooth muscle actin were also increased in these grafts. These data show that hyperglycemia and insulin status influence laminin isoform expression and play important roles in mesangial development.

Actins↗
PubMed1996

Sonohysterographic imaging of the endometrial cavity.

Vaginal ultrasound is the most effective method of imaging the contents of the true pelvis in the female. Saline influsion sonohysterography (SIS) is a simple refinement of the standard vaginal sonographic exam. Here, we briefly describe and demonstrate our use of this latter technique.

Endometrial Neoplasms↗
PubMed1996

Phase I and pharmacokinetic study of oral UFT, a combination of the 5-fluorouracil prodrug tegafur and uracil.

UFT is an oral preparation combining the 5-fluorouracil (FU) prodrug tegafur (FT) and uracil (U) in a 1:4 ratio, which is commercially available in Japan for the treatment of breast and gastrointestinal cancers. We sought to determine the tolerance of daily oral UFT and to relate this tolerance to the pharmacokinetics of FT and/or the derived FU, while exploring the possibility of circadian FU kinetics contributing to the results. A 28-day schedule followed by 2 weeks rest was began at the initial level of 300 mg/m2/day administered either at 8 a.m. or at 6 p.m. At the following level, 400 mg/m2/day patients were randomly assigned to a split-dose administration or to the above single, timed dose administration. Intolerance to single dosing was clearly demonstrated, and only the split dosing was advanced to 500 mg/m2/day. When this level proved too toxic, 400 mg/m2 was studied further on a 7 a.m., 3 p.m., and 11 p.m. (every 8 h) schedule. Pharmacology was determined on selected patients. In the single dose administration, areas under the curves of FU were higher following p.m. dosing, although substantial interpatient variation was present. Toxicities (diarrhea and neutropenia) were more severe in patients receiving the drug in single daily doses. We conclude that the kinetics of FT are saturable, with disproportionate increases in area under the curve (and toxicities) as dose levels are increased. With divided dosing, tolerance improves. UFT at a dose of 400 mg/m2/day administered as three divided doses (every 8 h) is suitable for Phase II studies, although toxicity requiring cessation of drug administration prior to completion of 28-day cycles will occur in some patients.

Administration, Oral↗
PubMed1995

Induction of nodular sclerosis by insulin in rat mesangial cells in vitro: studies of collagen.

These studies evaluated the contribution of insulin to the development of the abnormal mesangial matrix that characterizes diabetic nephropathy and is common to mesangial cells in culture. Glomeruli were isolated from a single rat and divided into two aliquots. In one set (SI-MC), the insulin contained in the medium was only that contributed by the fetal calf serum (20%). For the other set, the tissue culture medium was supplemented with 1 microM insulin (SI+MC). Mesangial cell outgrowths from each condition were isolated, cloned, and propagated. At passage 4, mesangial cells were characterized by morphology and cell markers, and compared in terms of composition and appearance of the secreted extracellular matrix. SI-MC grew in nests of cells surrounded by a thin layer of matrix that was rich in collagen IV. In contrast, mesangial cells supplemented with insulin aggregated into macroscopic "hillocks" rich in collagens I and III as described previously. Insulin (1 microM) or IGF-I (0.1 microM) was subsequently added to the medium of SI-MC. Insulin, but not IGF-I, induced a change in culture morphology and collagen accumulation characteristic of SI+MC. In contrast to SI+MC, SI-MC express insulin receptors and at physiologic concentrations insulin is a more potent stimulator of MC proliferation than is IGF-I. Insulin-induced changes in the collagenous composition of the accumulated ECM were directionally correlated with the rate of collagen I synthesis measured by biosynthetic labeling experiments and collagens III and IV as determined by ELISA. These data demonstrate that insulin alters the phenotype of mesangial cells in culture and their expression of interstitial and basement membrane collagens. These observations implicate insulin as a factor in the pathogenesis of mesangial matrix accumulation in diabetic nephropathy. Furthermore, a method for culturing mesangial cells that accumulate an extracellular matrix that is similar in composition to normal mesangial matrix provides a new model system for future studies of mesangial cell biology.

Animals↗
PubMed1994

Insulin induces a change in extracellular matrix glycoproteins synthesized by rat mesangial cells in culture.

Extracellular matrix (ECM) accumulation within the glomerular mesangium is a hallmark of progressive forms of renal disease. We recently succeeded in propagating mesangial cells (MC) from the time of explant without supplemental insulin which exhibit a matrix profile analogous to normal mesangium in vivo. We used these cells to characterize insulin-induced changes in biosynthesis and accumulation of three important matrix glycoproteins, laminin, fibronectin, and thrombospondin. Two clones of MC derived from glomeruli from a single rat were compared. MC grown in the absence of supplemental insulin (SI-MC) assemble a matrix rich in fibronectin with much smaller accumulations of laminin and thrombospondin. In comparison, MC (SI+MC) grown chronically in the presence of 1 microM insulin have a greatly expanded ECM that immunostains less intensely with antibodies to fibronectin, but, it contains significant accumulations of laminin and thrombospondin. Following metabolic labeling of secreted proteins with 35S-methionine, total protein synthesis was measured, and specific ECM components were identified and quantitated by immunoprecipitation, SDS-PAGE and autoradiography. The rate of total protein synthesis was increased by 50% in SI+MC as compared to SI-MC, yet, individual proteins were increased or decreased. The rate of synthesis of fibronectin was decreased and the rate of synthesis of laminin and thrombospondin was increased by insulin. These changes were directionally correlated with the net accumulation of these proteins as shown by immunostaining. In addition to an increase in laminin synthesis, insulin treatment induced a change in the isoform of laminin expressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗