Search PubMed⌕ Search

Biomedical subjects

M Joyce

Publications and source records attributed to M Joyce.

At least 37 records · Page 2Linked to original sources
PubMed1998

Metastases that interfere with circulation.

OBJECTIVES: To review the nursing implications of select circulatory problems caused by metastatic cancer. DATA SOURCES: Journal articles, research studies, and book chapters relating to circulatory problems associated with metastatic disease. CONCLUSIONS: During the metastatic process, tumor cells can interfere with circulation. As a result, circulatory impairments can range from life threatening to manifestations that may alter a person's quality of life. IMPLICATIONS FOR NURSING PRACTICE: Oncology nurses have a responsibility to seek current knowledge about therapeutic and supportive care for persons experiencing circulatory alterations. Collaboration with colleagues can facilitate patient care in these clinical situations. Patient education can be supportive and may enhance optimal outcomes.

Ascites↗
PubMed1997

Evidence for decreased splanchnic glucose uptake after oral glucose administration in non-insulin-dependent diabetes mellitus.

The role of splanchnic glucose uptake (SGU) after oral glucose administration as a potential factor contributing to postprandial hyperglycemia in non-insulin-dependent diabetes mellitus (NIDDM) has not been established conclusively. Therefore, we investigated SGU in six patients with NIDDM and six weight-matched control subjects by means of the hepatic vein catheterization (HVC) technique. In a second part, we examined the applicability of the recently developed OG-CLAMP technique in NIDDM by comparing SGU and first-pass SGU during HVC with SGU during the OG-CLAMP experiment. The OG-CLAMP method combines a euglycemic, hyperinsulinemic clamp and an oral glucose tolerance test (75 g) during steady state glucose infusion (GINF). During HVC, SGU equals the splanchnic fractional extraction times the total (oral and arterial) glucose load presented to the liver. For OG-CLAMP, SGU was calculated as first-pass SGU by subtracting the integrated decrease in GINF over 180 min from 75 g. Cumulative splanchnic glucose output after oral glucose correlated significantly between both methods and was increased significantly in NIDDM patients (73.1+/-5.1 g for HVC, 76.5+/-5.5 for OG-CLAMP) compared with nondiabetic patients (46.7+/-4.4 g for HVC, 57.5+/-1.9 for OG-CLAMP). Thus, in NIDDM patients, SGU (7.4+/-2.1 vs. 37.8+/-5.9% in nondiabetic patients, P < 0.001) and first-pass SGU (4.7+/-1.7 vs. 26.5+/-5.1% in nondiabetic patients, P < 0.01) were decreased significantly during HVC, as was SGU during OG-CLAMP (3.9+/-1.7 vs. 23.4+/-2.5% in nondiabetic patients, P < 0.0001). SGU measured during OG-CLAMP correlated significantly with SGU (r = 0.87, P < 0.05 for NIDDM patients; r = 0.94, P < 0.01 for nondiabetic patients) and first-pass SGU (r = 0.87, P < 0.05 for NIDDM patients; r = 0.84, P < 0.05 for nondiabetic patients) during HVC. In conclusion, (a) SGU after oral glucose administration is decreased in NIDDM as measured by both methods, and (b) SGU during the OG-CLAMP is well-correlated to SGU and first-pass SGU during HVC in NIDDM. The decrease in SGU in NIDDM might contribute to postprandial hyperglycemia in diabetic subjects.

Administration, Oral↗
PubMed1997

Regulation of actin polymerization in cell-free systems by GTPgammaS and Cdc42.

We have established a cell-free system to investigate pathways that regulate actin polymerization. Addition of GTPgammaS to lysates of polymorphonuclear leukocytes (PMNs) or Dictyostelium discoideum amoeba induced formation of filamentous actin. The GTPgammaS appeared to act via a small G-protein, since it was active in lysates ofD. discoideum mutants missing either the alpha2- or beta-subunit of the heterotrimeric G-protein required for chemoattractant-induced actin polymerization in living cells. Furthermore, recombinant Cdc42, but not Rho or Rac, induced polymerization in the cell-free system. The Cdc42-induced increase in filamentous actin required GTPgammaS binding and was inhibited by a fragment of the enzyme PAK1 that binds Cdc42. In a high speed supernatant, GTPgammaS alone was ineffective, but GTPgammaS-loaded Cdc42 induced actin polymerization, suggesting that the response was limited by guanine nucleotide exchange. Stimulating exchange by chelating magnesium, by adding acidic phospholipids, or by adding the exchange factors Cdc24 or Dbl restored the ability of GTPgammaS to induce polymerization. The stimulation of actin polymerization did not correlate with PIP2 synthesis.

Actins↗
PubMed1997

Flow cytometric cell sorting combined with molecular chimerism analysis to detect minimal recurrent leukemia: good news and bad news.

Allogeneic BMT offers the possibility of cure for a variety of hematopoietic malignancies, but disease relapse remains a major cause of treatment failure. This report describes two cases in which flow cytometric cell sorting (FACS) and molecular chimerism analysis were combined to increase the sensitivity of minimal residual disease (MRD) detection. In the first case this approach was used to demonstrate that a suspicious phenotype was not recurrent leukemia, thus preventing the use of potentially toxic therapy. In the second case the recurrence of a leukemia which was undetectable by conventional analysis was confirmed. The potential benefits of combining these MRD detection methods are discussed.

Adolescent↗
PubMed1996

Comparison of changes in endothelial adhesion molecule expression following UVB irradiation of skin and a human dermal microvascular cell line (HMEC-1).

We have assessed the pattern of dermal endothelial adhesion molecule expression following broadband UVB irradiation in vivo and in vitro. Skin biopsies were taken from 4 human volunteers at baseline and at 4, 8 and 24 h post-irradiation with 2.5 minimal erythema doses of UVB. Sections were stained immunohistochemically for E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1). CD31 and neutrophil elastase. The effect of direct UVB irradiation on E-selectin, ICAM-1 and VCAM-1 was examined in a human dermal microvascular endothelial cell line, HMEC-1. Cultured HMEC-1 were irradiated with 2.5-40 mJ/cm2 of UVB, and assessed for adhesion molecule expression by immunofluorescence microscopy and fluorescence-activated cell sorter analysis. In vivo, E-selectin was minimally expressed on EC at baseline and was induced by 4 h following irradiation, P < 0.01. ICAM-1 was moderately expressed at baseline and appeared mildly induced at 24 h, although this did not reach statistical significance. VCAM-1 was weakly expressed in unirradiated skin while CD31 was moderately expressed, but neither was induced by UVB irradiation. A significant neutrophilic infiltrate appeared by 8 h and was maximal at 24 h, P < 0.05. Neutrophil infiltration correlated with E-selectin expression, r = 0.96. In HMEC-1, ICAM-1 was upregulated at 24 h post-irradiation, with an increase in mean channel fluorescence from 100% at baseline to 145 (SD12)% at 24 h, P < 0.05. No change was seen in expression of E-selectin, VCAM-1 or CD31. These studies support the involvement of endothelial adhesion molecules E-selectin and ICAM-1 in UVB-induced inflammation. Whereas ICAM-1 is upregulated by direct irradiation of endothelial cells, E-selectin stimulation appears to be an indirect effect.

Adult↗
PubMed1995

Effects of treatment setup variation on beam's eye view dosimetry for radiation therapy using the multileaf collimator vs. the cerrobend block.

PURPOSE: The purpose of this study is to quantify and compare retrospectively the effects of treatment setup variation on beam's eye view (BEV) dosimetry for radiation therapy using a multileaf collimator (MLC) vs. cerrobend block. METHODS AND MATERIALS: A study was performed on a group of 18 patients with cancer of the head and neck, lung, and pelvis who were treated with irregularly shaped fields. The BEV dosimetry of the fields shaped with cerrobend blocks and the MLC was measured with films at the depth of dose prescription in a solid water phantom. A "one-half-leaf" insertion convention was used to shape the MLC. In addition, an average of 15 sequential daily port films was taken per patient during the course of radiotherapy. The port films were aligned with the prescription film for each patient. Systematic error and random error of treatment setup for each patient were calculated. The effects of setup variation were incorporated by convolving the patient portal imaging data with the corresponding BEV film dosimetry. Two parameters were used to quantify the BEV dosimetry. First, the field penumbra width was calculated, which represented the average of the normal separations between 20 and 80% isodose lines along the prescription outline. Second, the ratio of areas covered by the 90 and 20% isodose lines, A90/20, was determined. The BEV dosimetry was then characterized with and without the effects of treatment setup variation. In addition, the difference in BEV dosimetry between the cerrobend block and the MLC was used to estimate the corresponding changes in tumor control probability (TCP). These changes were also compared to the changes in TCP for the treatment with or without the effects of random setup variation. RESULTS: With or without daily setup variation, the use of cerrobend block was more favorable than the MLC in terms of the field penumbra width and A90/20 for all treatment sites. In the absence of daily variation, the MLC field penumbra width was on average 1.3 mm larger than that of the cerrobend block, and 0.9 mm larger in the presence of daily setup variation. Similarly, the ratio A90/20 of the cerrobend block was on average 0.03 larger than that of MLC without daily setup variation, and 0.02 with daily setup variation. The difference in field penumbra width and A90/20 between the MLC and the cerrobend block was slightly reduced due to the effects of daily setup variation. For both the cerrobend block and the MLC, daily setup variation produced a significant increase in the field penumbra width, 2.3 mm for the cerrobend block and 1.9 mm for the MLC, and a decrease in the A90/20, 0.06 for the former and 0.05 for the latter. The change due to the daily setup variation was about a factor of 2 larger than the changes due to replacing the cerrobend block with the MLC. Using the TCP model, the change in TCP due to the daily setup variation was more than a factor of 3 larger than the change in TCP due to replacing the cerrobend block with the MLC. It was noted that the average changes in the penumbra, the A90/20 and the TCP calculated for the patient population did not adequately describe the changes for the individual patient. CONCLUSION: Our results do not show significant dosimetric differences between the MLC and the cerrobend block in conventional radiation treatment, whether or not daily setup variation was taken into consideration. The effects of daily setup variation alone produced a larger dosimetric change. The same results were obtained when the data were applied to calculate changes in TCP. For optimal radiation therapy, efforts should be concentrated on reducing daily setup variation. Our results also demonstrate the importance of frequent evaluation of MLC treatment using electronic portal imaging devices.

Equipment Design↗
PubMed1995

Role of basal insulin in maintenance of intracellular glucose metabolic pathways in non-insulin-dependent diabetes mellitus.

Impairments of both basal and insulin-stimulated oxidative (Gox) and nonoxidative (Nox) glucose metabolism are documented to exist in non-insulin-dependent diabetes mellitus (NIDDM). Although these defects have been well characterized during insulin stimulation, little is known about the effects of basal insulin or its deficiency on intracellular glucose metabolism in NIDDM. To determine the physiological significance of basal insulin in the maintenance of glucose metabolism in NIDDM, we studied nine subjects with NIDDM in the basal and insulin-deficient state produced by 3 hours of somatostatin (SRIF) infusion (0.08 pmol/kg/min). Glucose turnover rates were quantified by [3-3H]glucose turnover, and substrate oxidation was assessed by a combination of indirect calorimetry and urinary nitrogen measurements. Skeletal muscle glycogen synthase (GS) and pyruvate dehydrogenase (PDH) activities were also measured in the basal state and during SRIF infusion. Basal glucose levels were maintained during SRIF infusion by exogenous glucose infusion (12.5 +/- 0.9 mmol/L in the basal state v 12.8 +/- 0.8 during SRIF infusion, P = NS). During the last hour of SRIF infusion, plasma C-peptide levels declined by 88% from 0.73 +/- 0.11 to 0.09 +/- 0.02 nmol/L (P < .001), and serum insulin concentrations were undetectable (< 14 pmol/L). During insulinopenic conditions, rates of glucose uptake (GU) were decreased by 12% from basal level of 2.26 +/- 0.13 to 1.99 +/- 0.12 mg/kg/min (P < .05), and were entirely accounted for by reduced rates of Gox (1.01 +/- 0.10 to 0.65 +/- 0.14 mg/kg/min, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1995

Actin filament barbed-end capping activity in neutrophil lysates: the role of capping protein-beta 2.

A barbed-end capping activity was found in high speed supernates of neutrophils lysed in submicromolar calcium. In dilute supernate (> or = 100-fold dilution of cytoplasm), this activity accounted for most of the inhibition of barbed-end elongation of pyrenyl-G-actin from spectrin-F-actin seeds. Pointed-end elongation from gelsolin-capped F-actin seeds was not inhibited at comparable concentrations of supernate, thus excluding actin monomer sequestration as a cause of the observed inhibition. Most of the capping activity was due to capping protein-beta 2 (a homologue of cap Z). Thus, while immunoadsorption of > or = 95% of the gelsolin in the supernate did not decrease capping activity, immunoadsorption of capping protein-beta 2 reduced capping activity proportionally to the amount of capping protein-beta 2 adsorbed. Depletion of > 90% of capping protein-beta 2 from the supernate removed 90% of its capping activity. The functional properties of the capping activity were defined. The dissociation constant for binding to barbed ends (determined by steady state and kinetic analyses) was approximately 1-2 nM; the on-rate of capping was between 7 x 10(5) and 5 x 10(6) M-1 s-1; and the off-rate was approximately 2 x 10(-3) s-1. The concentration of capper free in the intact cell (determined by adsorption of supernate with spectrin-actin seeds) was estimated to be approximately 1-2 microM. Thus, there appeared to be enough high affinity capper to cap all the barbed ends in vivo. Nevertheless, immediately after lysis with detergent, neutrophils contained sites that nucleate barbed-end elongation of pyrenyl-G-actin. These barbed ends subsequently become capped with a time course and concentration dependence similar to that of spectrin-F-actin seeds in high speed supernates. These observations suggest that, despite the excess of high affinity capper, some ends either are not capped in vivo or are transiently uncapped upon lysis and dilution.

Actin Cytoskeleton↗
PubMed1995

A noninvasive method to measure splanchnic glucose uptake after oral glucose administration.

We have developed a noninvasive method to estimate splanchnic glucose uptake (SGU) in humans (oral glucose clamp technique [OG-CLAMP]), which combines a hyperinsulinemic clamp with an oral glucose load (oral glucose tolerance test). We validated this method in 12 nondiabetic subjects using hepatic vein catheterization (HVC) during an oral glucose tolerance test. During HVC, splanchnic blood flow increased from 1,395 +/- 64 to 1,935 +/- 109 ml/min, returning to basal after 180 min and accounted for 45 +/- 7% of SGU in lean and 19 +/- 5% in obese subjects (P < 0.05). SGU estimated during the OG-CLAMP was 22 +/- 2% of the glucose load, and this was significantly correlated (r = 0.90, P < 0.0001) with SGU (35 +/- 4%) and with first pass SGU (24 +/- 3%; r = 0.83, P < 0.001) measured during HVC. SGU was higher in obese than in lean subjects during OG-CLAMP (27 +/- 1% vs 18 +/- 3%, P < 0.01) and HVC (44 +/- 4% vs 26 +/- 5%, P < 0.05). In conclusion, SGU during the OG-CLAMP is well correlated to SGU measured during HVC. An increase in splanchnic blood flow is a major contributor to SGU in lean subjects. SGU is increased in obese subjects as measured by both methods.

Adult↗
PubMed1995

Contribution of obesity to defects of intracellular glucose metabolism in NIDDM.

OBJECTIVE: To examine the contribution of obesity to insulin resistance and abnormalities of intracellular glucose and fat metabolism in NIDDM. RESEARCH DESIGN AND METHODS: Glucose turnover measurements and indirect calorimetry were performed in 10 obese non-insulin-dependent diabetes mellitus (NIDDM) and 10 lean NIDDM subjects (body mass index 35.3 +/- 1.0 vs. 24.1 +/- 0.5 kg/m2, P < or = 0.001) in the basal state and during hyperinsulinemic (720 pmol.m-2.min-1) euglycemic (5.0-5.5 mmol/l) clamps. RESULTS: Obese and lean NIDDM subjects demonstrated similar basal rates of glucose uptake (GU) (1.15 +/- 0.08 vs. 1.26 +/- 0.08 mmol/min, NS) as well as oxidative (0.49 +/- 0.07 vs. 0.53 +/- 0.05 mmol/min, NS) and nonoxidative (0.67 +/- 0.10 vs. 0.73 +/- 0.12 mmol/min, NS) glucose metabolism. During hyperinsulinemic glucose clamp studies, rates of GU were lower in obese NIDDM subjects (34.1 +/- 2.3 vs. 55.2 +/- 3.8 mumol.kg fat-free mass [FFM]-1.min-1, P < or = 0.001) as were rates of oxidative (14.1 +/- 1.3 vs. 22.1 +/- 2.1 mumol.kg FFM-1.min-1, P < or = 0.005) and nonoxidative (20.0 +/- 2.3 vs. 33.1 +/- 3.6 mumol.kg FFM-1. min-1, P < or = 0.01) glucose metabolism. Although absolute rates of insulin-stimulated GU were decreased in the obese group, the relative distribution into glucose oxidation (GOX) and nonoxidative glucose metabolism (NOX) was comparable in both groups (GOX 42% in obese and 41% in lean subjects; NOX 58% in obese and 59% in lean subjects). The NIDDM groups had similar basal free fatty acid levels that were suppressed equally during hyperinsulinemic clamps. However, basal fat oxidation (Fox) was greater in the obese NIDDM group (103 +/- 11 vs. 73 +/- 8 mumol/min, P < or = 0.05) and was less suppressed to insulin (74 +/- 13 vs. 16 +/- 3 mumol/min, P < or = 0.001). CONCLUSIONS: These results indicate that when obesity is present in NIDDM subjects with this degree of hyperglycemia, insulin-stimulated GU is lower by 35-40%. Reduced GU in obese NIDDM subjects leads to decreased intracellular substrate availability and lower rates of oxidative and nonoxidative glucose metabolism. Insulin suppression of Fox is also impaired when obesity is present and may contribute to decreased insulin-mediated GU in NIDDM. We conclude that obesity increases insulin resistance in NIDDM primarily by effects on GU rather than the intracellular pathways of glucose metabolism.

Adipose Tissue↗
PubMed1994

Improvement in glucose tolerance and insulin resistance in obese subjects treated with troglitazone.

BACKGROUND: Troglitazone decreases insulin resistance and hyperglycemia in patients with non-insulin-dependent diabetes mellitus (NIDDM), but its effects on subjects without diabetes are not known. METHODS: We performed oral and intravenous glucose-tolerance tests, studies with the euglycemic-hyperinsulinemic clamp, meal-tolerance tests, and 24-hour blood-pressure measurements at base line and after the administration of troglitazone, 200 mg orally twice daily, or placebo for 12 weeks in 18 nondiabetic obese subjects, 9 of whom had impaired glucose tolerance. RESULTS: The mean (+/- SD) rates of glucose disposal increased from 4.7 +/- 1.7 to 6.0 +/- 1.7 mg per kilogram of body weight per minute (P = 0.004) and from 9.0 +/- 1.8 to 9.9 +/- 1.3 mg per kilogram per minute (P = 0.02) during insulin infusions of 40 and 300 mU per square meter of body-surface area per minute, respectively, in the troglitazone group. The insulin-sensitivity index, calculated from the results of intravenous glucose-tolerance tests, increased from 0.7 +/- 0.6 x 10(-4) to 1.6 +/- 0.9 x 10(-4) in subjects given troglitazone, and their glycemic response to oral glucose and to mixed meals decreased. The mean fasting plasma insulin concentration decreased by 48 percent (P = 0.002), and the plasma insulin response to oral glucose and mixed meals decreased by 40 and 41 percent, respectively. The changes were similar in the subjects with normal glucose tolerance and those with impaired glucose tolerance. Systolic and diastolic blood pressure decreased by 5 +/- 2 mm Hg (P = 0.05) and 4 +/- 2 mm Hg (P = 0.04), respectively, after treatment with troglitazone. There were virtually no changes in the placebo group. CONCLUSIONS: Troglitazone decreases insulin resistance and improves glucose tolerance in obese subjects with either impaired or normal glucose tolerance. The ability of troglitazone to reduce insulin resistance could be useful in preventing NIDDM:

Adult↗
PubMed1993

Alterations in growth phenotype and radiosensitivity after fractionated irradiation of breast carcinoma cells from a single patient.

PURPOSE: To investigate growth regulation and radiosensitivity in surviving clonogens after fractionated irradiation. METHODS AND MATERIALS: Four breast carcinoma cell lines isolated from the primary tumor (21NT, 21PT) and metastases (21MT-1, 21MT-2) of a single patient were exposed to cumulative radiation doses of 30 Gy yielding cell lines designated-IR with respect to their parent. The irradiated lines were then compared to their parent for serum-and growth factor-requirements under defined media conditions, ability to proliferate in soft agar, concentration of TGF-alpha in conditioned medium, and radiosensitivity. RESULTS: The irradiated lines showed no change in proliferative doubling times under serum- and growth factor-supplemented media conditions. A single line, 21MT-1-IR, acquired a limited ability to proliferate in serum-and growth factor-deplete medium with a day 2-4 doubling time of 44.5 hr. Three lines, 21MT-1-IR, 21MT-2-IR, and 21NT-IR, formed colonies in soft agar in contrast to none of the unirradiated parent lines. There were significant 6-8 fold increases in conditioned media TGF-alpha concentrations for 21MT-2-IR and 21NT-IR cells. The 21MT-1-IR and 21NT-IR cells were significantly less radiosensitive than their respective parent lines. This decrease in radiosensitivity appeared to be at least partially mediated by a released factor as the radiosensitivity of 21MT-1 cells was significantly decreased by pre-incubation with conditioned medium from 21MT-1-IR cells. CONCLUSION: Radiation-induced changes in growth phenotype vary with respect to clonal origin of the cell line and may influence the radiosensitivity of surviving clonogens after fractionated treatment.

Breast Neoplasms↗