Search PubMed⌕ Search

Biomedical subjects

W Dunlop

Publications and source records attributed to W Dunlop.

At least 19 recordsLinked to original sources
PubMed2001

Evaluation of feasibility and accuracy of sentinel node biopsy in early breast cancer.

BACKGROUND: Current literature has suggested that sentinel node biopsy may eventually replace axillary dissection as the nodal staging procedure of choice in early breast cancer. The goals of our study were to determine the accuracy of the sentinel node in predicting axillary nodal status and to evaluate the feasibility of incorporating sentinel node biopsy into a general surgical practice. METHODS: Between June 1999 and August 2000, 158 clinically node negative women with a histological diagnosis of T1 or T2 breast cancer were enrolled in the study. Both technetium sulfur colloid radiotracer and isosulfan blue dye were used to guide sentinel node biopsy. Sentinel node biopsy was always followed by a complete axillary dissection. The histopathology of sentinel nodes using serial sectioning and cytokeratin immunohistochemistry was compared with that of the nonsentinel nodes evaluated with routine hematoxylin and eosin stain. RESULTS: The overall sentinel node detection rate was 84% (89 of 106 patients). Sentinel node biopsy was most successful when a combination of radiotracer and dye was used. The staging accuracy of sentinel node biopsy was 98% (87 of 89); the sensitivity of the method was 94% (34 of 36); the false negative rate was 6% (2 of 36); the negative predictive value was 96% (53 of 55); and the rate of metastases to the sentinel node only was 56% (20 of 36). The results varied considerably among surgeons. CONCLUSIONS: The findings in our study support the hypothesis that the sentinel node is an accurate predictor of axillary nodal status in women with early breast cancer. These results suggest that the excellent findings in the literature can be reproduced by a group of general surgeons in a community-based hospital.

Adult↗
PubMed2000

Expression of the cyclic AMP-dependent transcription factors, CREB, CREM and ATF2, in the human myometrium during pregnancy and labour.

Elevated concentrations of cyclic AMP (cAMP) in the human myometrium may promote uterine quiescence during pregnancy by protein kinase A (PKA)-mediated phosphorylation and subsequent inactivation of myosin light-chain kinase, as well as by the phosphorylation and activation of cAMP-dependent transcription factors. In this context, we show that the altered expression of cAMP response-element binding protein (CREB), cAMP response-element modulator protein (CREM) and activating transcription factor 2 (ATF2) are implicated in the maintenance of myometrial quiescence during fetal maturation and the switch to uterine activation at term. Using electrophoretic mobility shift and super shift assays, as well as immunoblotting of paired myometrial tissue samples from non-pregnant, pregnant non-labouring and spontaneous labouring women, we defined the patterns of expression of various isoforms of these proteins in the human uterus. Here, we report spatio-temporal changes in the expression of a 43 kDa form of CREB, a 28 kDa CREM-like protein, and a novel 28 kDa ATF2-like protein which are differentially expressed, depending on the gestational state of the uterus. Changes in the pattern of expression of these potent transcription factors may have an important role in the control of uterine activity throughout pregnancy.

Activating Transcription Factor 2↗
PubMed1999

Recurrence and survival after surgical management of rectal cancer.

BACKGROUND: Reported local recurrence rates for rectal cancer are significantly reduced using a combination of superior surgical technique, in the form of total mesorectal excision, and routine radiotherapy. In an attempt to determine the effectiveness of current local management strategies, a review of Vancouver Island Cancer Centre patients with rectal cancer was performed and the overall local recurrence rate was identified. METHODS: We retrospectively reviewed the charts of 272 rectal cancer patients from 1988 to 1998. Two hundred and twenty-nine patients met inclusion criteria. Analysis of patient factors included age, gender, type of surgery, and adjuvant therapy. Tumors were assessed for level, stage, and grade. Local recurrence and distant metastases were also documented. Variables influencing local recurrence in this group were identified and disease-free and actuarial survival determined. RESULTS: Of 229 patients analyzed, 12.7% (29) had local recurrences. Variables influencing local recurrence were number of positive lymph nodes, vascular invasion, and neural invasion. There was no significant difference in local recurrence between patients having anterior resection and those having abdominoperineal resection. None of the patients who received preoperative radiotherapy had a local recurrence. Actuarial disease-free survival was 87% at 5 years. CONCLUSIONS: Limiting local recurrence is one of the most important goals in the treatment of rectal cancer. It is essential to identify those patients with "high risk" tumors as identified by endorectal ultrasound or pathologic features. These patients comprise the group most likely to benefit from a routine mesorectal excision combined with adjuvant radiotherapy.

Aged↗
PubMed1998

The responsiveness of isolated human hand vein endothelial cells in normal pregnancy and in pre-eclampsia.

1. Human hand vein endothelial cells were isolated from blood obtained by traumatic venepuncture. Cells were identified as endothelial by staining with endothelium-specific antibodies. The subject groups studied were (i) non-pregnant, (ii) pregnant (mean, 35 weeks gestation) and (iii) pre-eclamptic women (mean, 36 weeks gestation). 2. Fura-2 was used to measure agonist-induced responses in intracellular Ca2+ in single endothelial cells isolated and maintained in vitro. All of the cells examined responded to adenosine triphosphate (ATP) with a large transient increase in Ca2+ followed by a sustained plateau. 3. The responses to ATP were significantly larger in the cells from pregnant women than in those from non-pregnant and pre-eclamptic women, but no other differences were observed. The amplitudes of the responses to ATP were (means +/- s.e.m.) 0.56 +/- 0.04, 1.42 +/- 0.24 and 0.65 +/- 0.09 fura-2 ratio units for cells from non-pregnant, pregnant and pre-eclamptic subjects, respectively. 4. In cells isolated from non-pregnant subjects, the amplitude of the responses to carbachol, histamine and bradykinin were all smaller than those activated by ATP: 5.1, 13.9 and 4.4 %, respectively. Not all cells responded to these agonists: 25 % responded to carbachol, 70.5 % responded to histamine and 12.5 % responded to bradykinin. Sixty-five per cent of the cells from normotensive pregnant subjects responded to bradykinin compared with 25 % in the non-pregnant and 13.9 % in the pre-eclamptic subjects. 5. These data suggest that there may be differences in the responsiveness of venous endothelial cells in pregnancy and that pre-eclamptic cells behave differently.

Adult↗
PubMed1998

Gestational changes in the levels of transforming growth factor-beta1 (TGFbeta1) and TGFbeta receptor types I and II in the human myometrium.

As term approaches, a number of key proteins [contraction-associated proteins (CAPs)] are expressed within the human myometrium that are essential for the activation of powerful coordinated contractions during labor. The nature of the signals that switch on the synthesis of CAPs in vivo is not known. The ryanodine-sensitive intracellular Ca2+ release channel (RyR2) is a CAP whose expression in vitro is activated by transforming growth factor-beta (TGFbeta). The present experiments were performed to determine whether TGFbeta and TGFbeta receptors are present in the human myometrium at term and to explore the idea that they might form part of a signaling system in vivo. TGFbeta receptor types I and II, but not III, were demonstrated in myometrial smooth muscle in tissue taken from nonpregnant, pregnant nonlaboring, and spontaneous laboring women. Western blotting was used subsequently to determine the relative expression of TGFbeta receptor types I and II. Using nonpregnant myometrium as a baseline control the levels of expression of receptor types I and II were significantly increased by 168 +/- 19% (n = 6) and 162 +/- 22% (n = 7) in pregnant nonlaboring myometrium. In spontaneous laboring myometrium the levels of TGFbeta receptor type I and II expression were 93 +/- 12% (n = 6) and 85 +/- 11% (n = 7), respectively, compared to nonpregnant control values and were significantly lower than levels in pregnant nonlaboring tissues. The total TGFbeta1 levels in the myometrial tissues were 334 +/- 10, 534 +/- 73, and 674 +/- 106 pg/g tissue wet wt in nonpregnant, pregnant nonlaboring, and spontaneous laboring myometrium (n = 3 in each group), respectively. Thus, the TGFbeta signaling system appears to be up-regulated in the myometrium before the onset of parturition. The apparent loss of receptors in the spontaneous laboring samples in the presence of elevated total levels of TGFbeta may be indicative of agonist-induced receptor down-regulation. These observations support the idea that cytokines, in particular TGFbeta1, may play a role in the normal processes that prepare the myometrium for parturition at term.

Blotting, Western↗
PubMed1997

Differential expression of ryanodine receptor RyR2 mRNA in the non-pregnant and pregnant human myometrium.

We describe here the expression of the ryanodine receptor isoforms RyR2 and RyR3 in human non-pregnant and pregnant (non-labouring) myometrium, and in isolated cultured myometrial cells. The mRNA encoding the RyR3 isoform was found in both non-pregnant and pregnant myometrial tissue samples; however, the mRNA for RyR2 was found only in pregnant samples. It can be speculated that the appearance of this additional isoform in the pregnant myometrium may increase the ability of this tissue to contract at term. Control of expression of the RyR2 gene may therefore be another example of an up-regulated signalling system in pregnancy. Although the mRNA for RyR3 was expressed in cultured myometrial cells, the mRNA for RyR2 could not be detected. Thus cultured myometrial cells appear to be similar to the non-pregnant myometrium. The cytokine transforming growth factor beta (TGF-beta) has been reported to alter RyR mRNA expression in many cell types. After treatment with TGF-beta, both RyR2 and RyR3 mRNAs could be detected in cultured myometrial cells. These observations support the idea that the expression of the RyR2 isoform is up-regulated both in pregnancy and in TGF-beta-treated cultured myometrial cells. Using measurements of 45Ca2+ release, we have further demonstrated that cultured human myometrial cells show a significant augmentation of both the Ca2+-induced Ca2+ release (CICR) mechanism and ryanodine-induced Ca2+ release after treatment with TGF-beta. Additionally, caffeine was able to induce Ca2+ release and sensitize the CICR mechanism to ryanodine. Thus we suggest that the appearance of RyR2 mRNA leads to the expression of this receptor/channel protein with identifiable pharmacological characteristics. These results are discussed in the context of the potential role of gene activation in the process of maturation of the human myometrium during pregnancy.

Adult↗
PubMed1996

Erythrocyte ion and water balance and membrane potential in the puerperium of normal pregnancy.

OBJECTIVE: To examine the balance of erythrocyte ions and water during the rapid changes in plasma osmolality in the early puerperium, and during the subsequent period of sustained readjustment. DESIGN: A serial study from the third trimester of pregnancy to 20 weeks after delivery. PARTICIPANTS: Thirty-five primiparous women who had experienced no antenatal complications. MAIN OUTCOME MEASURES: Plasma osmolality, erythrocyte hydration, potassium, chloride and sodium were measured and nondiffusible ion content and erythrocyte membrane potential calculated. Plasma sodium, potassium and chloride were also measured. RESULTS: During the first week after delivery plasma osmolality increased (280 (SEM 0.52)-289 (SEM 0.64) mosmol/kg; P < 0.001) but erythrocyte hydration did not decrease (2.060 (SEM 0.018)-2.067 (SEM 0.021) 1/kg dry cells) because of an increase in total cell osmole content (577 (SEM 5.31)-597 (SEM 6.15) mosmol/kg dry cells; P = 0.001). This increase included nondiffusible anions, chloride and potassium. These changes in ionic balance did not affect membrane potential. After the first week of the puerperium and up to the 20th week, plasma osmolality was stable but erythrocyte osmole content and hydration both decreased. This was due to a decrease in nondiffusible anions and potassium with a smaller increase in chloride leading to a decrease in membrane potential (-14.31 (SEM 0.34)mV to -12.66 (SEM 0.28)mV; P < 0.001). CONCLUSIONS: A rapid increase in intracellular osmoles can occur in the mature erythrocyte and probably precedes the decrease in plasma osmolality in the puerperium. Changes in erythrocyte homeostasis in the first week of the puerperium can be accounted for by alterations in nondiffusible anions. After the first week of the puerperium it appears that the functional organisation of the membrane is changing.

Erythrocyte Membrane↗
PubMed1995

Retinoic acid receptors and retinoid binding proteins in endometrial adenocarcinoma: differential expression of cellular retinoid binding proteins in endometrioid tumours.

Retinoic acid is apparently required for the normal differentiation of reproductive epithelium. Cellular abnormalities in retinoid homeostasis could be a factor in the development of endometrial malignancy. We have thus investigated the expression of nuclear retinoic acid receptors (RARs and RXRs) and cellular binding proteins for retinol (CRBP) and retinoic acid (CRABP) in endometrial adenocarcinoma of the endometrioid histological subtype. Ten grade I, II grade 2 and 10 grade 3 tumour samples, as well as 4 samples of severe atypical precancerous endometrial hyperplasia, were studied. No significant difference in expression of RAR-beta was detected in tumour samples compared with normal epithelial cells. RAR-gamma was significantly elevated in grade 1 and 2 carcinomas, but this may be due to greater stromal cell involvement in these lower grade tumours. There was significant elevation of CRBP I mRNA in tumour samples. Furthermore, although undetectable in normal endometrial epithelium, CRABP I was expressed in 3/II grade 2 and 9/10 grade 3 carcinomas, with expression being significantly higher where the primary tumour had invaded more than 50% of the total myometrial thickness. Analysis of 2 epithelial-like endometrial adenocarcinoma cell lines supported the idea that CRABP I expression is characteristic of poorly differentiated endometrial adenocarcinoma. Our data suggest that alterations in mechanisms of retinoid homeostasis are a feature of endometrial adenocarcinoma and may contribute to the severity of disease.

Adenocarcinoma↗
PubMed1994

A serial study of erythrocyte sodium pump kinetics and sodium content in the puerperium.

OBJECTIVE: Our purpose was to describe the alterations in erythrocyte sodium pump kinetics and sodium content occurring during the puerperium. STUDY DESIGN: Twelve healthy primigravid women were studied serially from late pregnancy until 20 weeks after delivery. Erythrocyte sodium pump rate constant, maximum velocity, and sodium affinity were calculated from the ouabain-sensitive sodium flux measured in whole blood and in erythrocytes in which sodium content had been altered with the ionophore nystatin. The Student t test was used to compare the regression coefficients of the values plotted against log time for specific periods. RESULTS: The sodium pump rate constant, maximum velocity, and sodium affinity were lower 20 weeks after delivery than in late pregnancy (0.339 +/- 0.018 vs 0.399 +/- 0.016/hr, 7.02 +/- 0.08 vs 9.98 +/- 0.078 mmol/kg/hr, 2.65 +/- 0.21 vs 3.16 +/- 0.20 mmol/kg). The decrease in the rate constant commenced after 4 days of the puerperium, whereas the decrease in maximum velocity and Michaelis-Menten constant did not commence until after 2 weeks. Erythrocyte sodium content was greater 20 weeks after delivery than in late pregnancy (4.71 +/- 0.20 vs 4.14 +/- 0.15 mmol/kg cells) and the increase was gradual over the time studied. CONCLUSIONS: After delivery the rate constant of the sodium pump measured in plasma and the erythrocyte sodium content changed before any significant alteration in the maximum velocity of the pump. The return of sodium pump function to the nonpregnant state continues beyond 6 weeks after delivery.

Erythrocytes↗
PubMed1994

Renal haemodynamics and tubular function in human pregnancy.

In human pregnancy, effective renal plasma flow and glomerular filtration rate increase to levels 50-80% above non-pregnant values. The increments occur shortly after conception, persist throughout the second trimester and reduce slightly in late pregnancy. The hyperfiltration of pregnancy does not seem to be a potentially damaging process, as intraglomerular pressure remains unchanged. The increased excretion of glucose and other nutrients, as well as uric acid and protein, is related in part to altered tubular function. Renal physiology is altered so much in pregnancy that non-pregnant norms cannot be used in antenatal care.

Adult↗
PubMed1994

Cellular retinoid binding proteins and nuclear retinoic acid receptors in endometrial epithelial cells.

Retinoic acid, one of the most potent of the naturally occurring retinoids (retinol and derivatives), is required in vivo for the maintenance of epithelial cell growth. This study describes the pattern of expression of nuclear retinoic acid receptors (RARs and RXRs), and cellular binding proteins for retinol and retinoic acid (CRBP I, CRABP I and II), in endometrial epithelial cells. The effects of retinoic acid on the expression of these receptors in endometrial epithelial cells have also been studied and compared with its effects in endometrial stromal cells. Messenger RNA for RAR-alpha, RAR-beta, RAR-gamma, RXR-alpha, CRBP I and CRABP II was detected by Northern blotting of total RNA extracted from cultured epithelial cells. In comparison with stromal cell RNA that was used as an internal standard, CRBP I appeared to be more abundant in epithelial cells, whereas CRABP II appeared to be more abundant in the stromal cells. This implies that the intracellular concentration of retinoic acid may be maintained at higher levels in epithelial cells compared to stromal cells. In addition, the response of the two cell types to retinoic acid differs: RAR-beta is induced in stromal cells treated with all-trans retinoic acid but not in epithelial cells. From these data we suggest that retinoid physiology differs between endometrial epithelial and stromal cells. Furthermore, by analogy with other studies, we propose that retinoic acid may be maintained at a higher intracellular concentration in endometrial epithelial cells to facilitate differentiation to a glandular phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Erythrocyte sodium lithium countertransport in normal and hypertensive pregnancy: relation to haemodynamic changes.

OBJECTIVE: To establish the changes in erythrocyte sodium lithium countertransport (SLC) with advancing normal pregnancy and to determine if these changes were different in pregnancy induced hypertension (PIH). The changes in both groups were assessed in relation to haemodynamic changes. DESIGN: SLC, mean arterial pressure (MAP), cardiac output (CO) and total peripheral vascular resistance (TPVR) were determined serially during normal pregnancy and cross-sectionally in PIH. Women were studied again 20 weeks after delivery where possible. SETTING: Routine antenatal clinic and antenatal ward of a regional reference centre. SUBJECTS: Fifty-one normal primigravid women were studied serially and 41 primigravid women with PIH were studied at time of diagnosis. RESULTS: During normal pregnancy SLC (mmol Li/h/l cells) increased from a nonpregnant value of 0.24 +/- 0.02 (mean +/- SEM) to 0.32 +/- 0.02 at 14 weeks, and 0.37 +/- 0.02 at 20 weeks gestation. This was maintained until 38 weeks (0.40 +/- 0.02). The increase until 20 weeks occurred at the time of greatest change in CO (5.10 +/- 0.18 to 6.79 +/- 0.20 l/min) and TPVR (1327 +/- 58 to 969 +/- 33 dyn/s/cm-5). The decrease in TPVR with a rise in SLC is opposite to the relation reported in essential hypertension so that a functional relation is unlikely. However, the changes within pregnancy were positively correlated (r = 0.43, P < 0.01). In hypertensive pregnancies TPVR was elevated compared with normotensive pregnancies (1543 +/- 100 vs 1090 +/- 37) but the SLC was not different from that found in normotensive pregnancies (0.43 +/- 0.02 vs 0.40 +/- 0.02). CONCLUSIONS: The changes in SLC activity suggest dynamic effects on erythrocyte membrane function during pregnancy. However, no differences could be found between normal and hypertensive pregnancy and SLC is unlikely to be of value as a marker of hypertensive risk during pregnancy.

Adult↗
PubMed1993

Alterations in erythrocyte chloride content accompanying the changes in erythrocyte hydration and potassium content in normal human pregnancy: a comparison with pregnancy induced hypertension.

OBJECTIVES: To determine whether the change in erythrocyte potassium content in normal human pregnancy is accompanied by a similar change in erythrocyte chloride content. To assess erythrocyte hydration and potassium and chloride content in pregnancies complicated by proteinuric pregnancy induced hypertension. DESIGN: A serial study during and after normal pregnancy. A comparative study during and after pregnancies complicated by proteinuric pregnancy induced hypertension (PIH). Erythrocyte hydration, total osmoles, potassium and chloride and plasma osmolality were determined. SETTING: University teaching hospital, UK. SUBJECTS: Twenty-eight women studied at 14, 28 and 36 weeks of normal pregnancy and ten women with PIH studied during the third trimester of pregnancy. All women were reinvestigated 20 weeks after delivery. RESULTS: The fall of erythrocyte potassium early in normal pregnancy (277.4 vs 265.2 mmol/kg; P < 0.02) and its rise between 28 and 36 weeks (272.3 vs 288.0 mmol/kg; P < 0.005) were accompanied by similar changes in erythrocyte chloride content (151.9 vs 131.1 mmol/kg; P < 0.001 and 129.4 vs 141.3 mmol/kg; P < 0.001, respectively). Plasma osmolality in PIH was raised above that normal in pregnancy (287.2 vs 283.0 mosm/kg; P < 0.005). In PIH, compared to normal pregnancy, erythrocyte hydration (2.00 vs 1.89 l/kg dry weight cells), total osmoles (573.0 vs 534.2 mosm/kg), potassium (303.0 vs 288.0 mmol/kg) and chloride (154.9 vs 141.3 mmol/kg) were greater. CONCLUSIONS: These findings further support the hypothesis that changes in plasma osmolality in pregnancy are secondary to alterations in cell osmoles and serve to limit changes in cell hydration. Erythrocyte composition and plasma osmolality are altered in PIH.

Chlorides↗
PubMed1993

The effect of the oxytocin antagonists, CAP 476 and F327, on calcium mobilisation in single cultured human myometrial cells.

OBJECTIVE: To investigate the mechanism of action of the oxytocin (OT) antagonists, CAP 476 and F327. DESIGN: A prospective descriptional study. SUBJECTS: Women undergoing caesarean section at term or hysterectomy. INTERVENTIONS: Myometrial cells were cultured from uterine biopsies. MAIN OUTCOME MEASURES: Intracellular calcium ([Ca2+]i), determined in single cells. RESULTS: Application of OT caused a transient increase in [Ca2+]i. CAP 476 abolished and F327 reduced the response to OT but neither reduced the [Ca2+]i transient induced by cell depolarisation with 120 mmol K+. CAP 476 did not reduce transients caused by prostaglandin E2. F327 reduced the frequency of repetitive [Ca2+]i transients occurring during continuous application of OT. CONCLUSIONS: The results demonstrate that the antagonists reduce the effect of OT and that their action is relatively specific. Their mechanism of action as clinical tocolytic agents is discussed.

Calcium↗
PubMed1993

The actions of caffeine and 2,3-butanedione monoxime on calcium transients in human vascular smooth muscle.

Ca2+ mobilization by membrane depolarization or histamine application, was measured in isolated human uterine artery smooth muscle cells. Nifedipine, a Ca2+ channel blocker, was found to inhibit the depolarization-induced increase in [Ca2+]i but not the histamine-induced increase. This suggests the presence of functional voltage-dependent Ca2+ channels and agonist-induced mobilization of Ca2+ via a different mechanism. Caffeine inhibited both the depolarization- and histamine-induced increases in intracellular calcium. The mechanisms of inhibition do not involve cAMP and point to a complex action of caffeine at multiple sites. The dephosphorylating agent 2,3-butanedione monoxime (BDM) was found to block voltage-dependent Ca2+ changes but not agonist-induced changes suggesting a role for phosphorylation in the regulation of the Ca2+ channels in these cells.

Caffeine↗