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Biomedical subjects

C H Buckley

Publications and source records attributed to C H Buckley.

At least 19 recordsLinked to original sources
PubMed2005

Enhanced endothelium derived hyperpolarising factor activity in resistance arteries from normal pressure glaucoma patients: implications for vascular function in the eye.

BACKGROUND/AIMS: Endothelial cell dysfunction in the ocular circulation may contribute to normal pressure glaucoma (NPG). This study aimed to investigate the contributions made by endothelium derived relaxing factors to relaxation of (1) subcutaneous resistance arteries from patients with NPG, and (2) porcine ciliary arteries. METHODS: Human gluteal resistance arteries were isolated from seven patients with NPG and matched controls. Human and porcine arteries produced endothelium dependent relaxation when exposed to acetylcholine (ACh) (10(-9)-3 x 10(-5)M) or bradykinin (10(-10)-3 x 10(-6)M). Pharmacological agents were used to inhibit the nitric oxide pathway (l-arginine analogues, soluble guanylate cyclase inhibitor), endothelium derived hyperpolarising factor (EDHF) activity (potassium channel antagonists), and prostaglandin synthesis (cyclo-oxygenase inhibitors). RESULTS: In all arteries, endothelium dependent relaxation was attenuated by nitric oxide (NO) inhibition or potassium channel blockade, but not by cyclo-oxygenase inhibition. Inhibition of ACh mediated relaxation by potassium channel antagonists was greater (p<0.05) in patients with NPG (Emax, 55.4% (SD 8.16%) relaxation, n = 4) than controls (Emax, 81.8% (6.0%), n = 5). In contrast, combined inhibition of NO synthase (NOS) and cyclo-oxygenase produced similar inhibition of ACh mediated relaxation in both groups. CONCLUSIONS: The enhanced contribution of EDHF to ACh mediated relaxation in systemic resistance arteries from NPG patients may contribute to the maintained endothelium mediated relaxation in these vessels. EDHF also contributes significantly to bradykinin mediated relaxation in porcine ocular ciliary arteries. Therefore, similar changes in the balance of relaxing factors in the ocular circulation could influence the response of the eye to vascular endothelial dysfunction in NPG.

Acetylcholine↗
PubMed2001

Endothelium-derived hyperpolarizing factor and potassium use different mechanisms to induce relaxation of human subcutaneous resistance arteries.

This investigation examined the hypothesis that release of K(+) accounts for EDHF activity by comparing relaxant responses produced by ACh and KCl in human subcutaneous resistance arteries. Resistance arteries (internal diameter 244+/-12 microm, n=48) from human subcutaneous fat biopsies were suspended in a wire myograph. Cumulative concentration-response curves were obtained for ACh (10(-9) - 3x10(-5) M) and KCl (2.5 - 25 mM) following contraction with noradrenaline (NA; 0.1 - 3 microM). ACh (E(max) 99.07+/-9.61%; -LogIC(50) 7.03+/-0.22; n=9) and KCl (E(max) 74.14+/-5.61%; -LogIC(50) 2.12+/-0.07; n=10)-induced relaxations were attenuated (P<0.0001) by removal of the endothelium (E(max) 8.21+/-5.39% and 11.56+/-8.49%, respectively; n=6 - 7). Indomethacin (10 microM) did not alter ACh-induced relaxation whereas L-NOARG (100 microM) reduced this response (E(max) 61.7+/-3.4%, P<0.0001; n=6). The combination of ChTx (50 nM) and apamin (30 nM) attenuated the L-NOARG-insensitive component of ACh-induced relaxation (E(max): 15.2+/-10.5%, P<0.002, n=6) although these arteries retained the ability to relax in response to 100 microM SIN-1 (E(max) 127.6+/-13.0%, n=3). Exposure to BaCl(2) (30 microM) and Ouabain (1 mM) did not attenuate the L-NOARG resistant component of ACh-mediated relaxation (E(max), 76.09+/-8.92, P=0.16; n=5). KCl-mediated relaxation was unaffected by L-NOARG+indomethacin (E(max); 68.1+/-5.6%, P=0.33; n=5) or the combination of L-NOARG/indomethacin/ChTx/apamin (E(max); 86.61+/-14.02%, P=0.35; n=6). In contrast, the combination of L-NOARG, indomethacin, ouabain and BaCl(2) abolished this response (E(max), 5.67+/-2.59%, P<0.0001, n=6). The characteristics of KCl-mediated relaxation differed from those of the nitric oxide/prostaglandin-independent component of the response to ACh, and were endothelium-dependent, indicating that K(+) does not act as an EDHF in human subcutaneous resistance arteries.

Acetylcholine↗
PubMed2000

Functional heterogeneity of large and small resistance arteries isolated from biopsies of subcutaneous fat: implications for investigation of vascular pathophysiology.

Few studies using human subcutaneous resistance arteries acknowledge the possibility of functional heterogeneity in these vessels. Large ( approximately 500 microm) and small (> or = 200 microm) resistance arteries (n=11) and veins (n=5) were identified using physical, structural and functional criteria in 14 biopsies of human gluteal fat. Endothelium-dependent relaxation was not evident in veins, while, unlike small resistance arteries (E(max) 95.74+/-1.86%; -log IC(50) 7.28+/-0.09), large resistance arteries with an intact endothelium failed to respond to acetylcholine. These results suggest that large resistance arteries may lack muscarinic receptors on the endothelium and emphasise the importance of careful vessel selection and characterisation in studies using human resistance arteries.

Acetylcholine↗
PubMed2000

p53 and related proteins in epithelial ovarian cancer.

We conducted a retrospective immunohistochemical evaluation of the prognostic significance of the expression of p53 and the related proteins Bax, Bcl-2, growth arrest and DNA damage (Gadd45), murine double minute 2 (Mdm2) and p21(WAF1/CIP1) in chemonaive tumours taken from 66 patients with ovarian cancer. Ki-67 expression (a marker of cell proliferation) was also evaluated immunohistochemically, while apoptosis within malignant cells was determined with the terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling (TUNEL) assay. The expression of each of the following proteins was significantly associated in the tumours (P < 0.05 unless otherwise stated): Bax with Bcl-2 (P < 0.01); Bax with Mdm2; p21(WAF1/CIP1) with Gadd45 (P < 0.01); p21(WAF1/CIP1) with p53; p53 with Mdm2. Univariate analysis showed that expression of p53, Bax, bulk residual disease and International Federation of Gynecology and Obstetricians (FIGO) stage were all strongly correlated with response to chemotherapy (P < 0.01). Similarly, the FIGO stage and Ki-67 expression (P < 0.01), as well as pathological subtype and bulk residual disease (P < 0.05), were prognostic factors for disease progression. The FIGO stage and Ki-67 expression were significant prognostic factors for overall survival (P < 0.01), with Gadd45 expression and pathological subtype also significant (P < 0.05) in a univariate analysis. Multivariate analysis for response to chemotherapy showed that expression of p53, Bax and FIGO stage were all independent prognostic factors (P < 0.01). The FIGO stage was the most important independent prognostic factor for progression and survival on multivariate analysis (P < 0.01). However, Ki-67 expression was also an independent prognostic factor for disease progression (P < 0.05) and approached significance for survival (P = 0.055). Taken together, these data suggest that determination of Ki-67 expression could supplement established prognostic factors.

Adult↗
PubMed2000

Requirement for expert histopathological assessment of ovarian cancer and borderline tumors.

The distinction between borderline ovarian tumours (BOT) and ovarian carcinoma is made by histopathological assessment. Of 64 patients managed according to institutional BOT protocols, 27 (42%) had been referred with a diagnosis of ovarian carcinoma that was subsequently changed to BOT following histopathological review. The 70% 6-year event-free survival of the patients with a revised diagnosis was not significantly different from those who were referred with a diagnosis of BOT. This change in diagnosis is important as it avoids the need for chemotherapy for most patients and results in patients receiving appropriate information concerning prognosis. Interestingly, 24 patients (38.1%) reported a family history of epithelial cancer, a finding that has not been reported previously. Campaign

Adult↗
PubMed1999

Comparison of prophylactic oophorectomy specimens from carriers and noncarriers of a BRCA1 or BRCA2 gene mutation. United Kingdom Coordinating Committee on Cancer Research (UKCCCR) Familial Ovarian Cancer Study Group.

BACKGROUND: The natural history of ovarian cancer is not well understood and, to date, there is conflicting evidence as to whether or not there is a demonstrable precursor lesion. Some women at high risk of developing ovarian cancer because of their family history elect to have a prophylactic oophorectomy. To determine whether or not a recognizable premalignant lesion could be defined in familial ovarian carcinogenesis, we reviewed ovarian tissue specimens from women whose ovaries were removed prophylactically before gene testing became available and who were tested subsequently for BRCA1 or BRCA2 gene mutations. METHODS: We analyzed ovarian tissue specimens from 37 women. The specimens were examined for the presence of the following four features: inclusion cysts, clefts and fissures, ovarian epithelial metaplasia, and the presence of papillae on the ovarian surface epithelium. The specimens were also examined closely for the presence of dysplasia and occult neoplasia. Furthermore, the occurrence of endometriosis and benign ovarian tumors was documented in these women. The protein truncation test, nonradioactive single-stranded conformation polymorphism analysis, and heteroduplex analysis, followed by DNA sequencing, were used to identify BRCA1 or BRCA2 mutations in either blood samples or ovarian tissue specimens. RESULTS: Eleven women had inherited a mutated BRCA1 or BRCA2 gene; 26 women had not. There was no difference between these groups for any of the features studied. CONCLUSIONS: Our data suggest that many of the histologic "abnormalities" described in "normal" ovaries are, in fact, variations of the normal and are not associated with the development of cancer.

Adult↗
PubMed1998

Morphological and functional features of endometrial decidualization following long-term intrauterine levonorgestrel delivery.

Irregular bleeding remains a common reason for the discontinuation of progestin-only contraception. The levonorgestrel releasing intrauterine system (LNG-IUS) has profound morphological effects upon the endometrium. Specific features are gland atrophy and extensive decidual transformation of the stroma. Morphological changes in the endometrium may be associated with perturbation of mechanisms regulating normal endometrial function. This study describes endometrial stromal and glandular features prior to and up to 12 months following insertion of the LNG-IUS. Comparison is made with first trimester decidua. In order to elucidate further mechanisms governing endometrial function with local intrauterine delivery of LNG, we here report histological features consistent with decidualization; a significant increase in granulocyte-macrophage colony stimulating factor (GM-CSF) immunoreactivity in decidualized stromal cells; glandular and stromal prolactin receptor expression and an infiltrate of CD56 + large granular lymphocytes and CD68 + macrophages. We are unaware of previous reports which have documented longitudinally both morphological and functional observations in endometrium exposed to local intrauterine levonorgestrel delivery. These studies demonstrate that long-term administration of intrauterine levonorgestrel results in features of altered morphology and function. No correlation was apparent between the end points in the study and the bleeding patterns described by the subjects. Further evaluation of these features in the context of menstrual bleeding experience may contribute to a better understanding of this troublesome side-effect which often leads to dissatisfaction and discontinuation of the intrauterine system.

Adult↗
PubMed1998

Possible role for nitric oxide releasing nerves in the regulation of ocular blood flow in the rat.

AIM: To investigate the role of nitrergic nerves in the regulation of ocular blood flow. METHODS: Conscious, lightly restrained rats were treated with either the neuronal nitric oxide synthase inhibitor 7-nitroindazole (7-NI), or the nonselective inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), and ocular blood flow was measured ex vivo from tissue samples, using the fully quantitative [14C]-iodoantipyrine technique. RESULTS: In the peripheral circulation, L-NAME produced an increase in arterial blood pressure (+22%) while 7-NI had no effect. In contrast, both 7-NI and L-NAME produced significant decreases in ocular blood flow (-31% and -59% respectively). The ocular vascular resistance calculated from ocular blood flow and mean arterial blood pressure increased by 29% following 7-NI, but by 130% following L-NAME. CONCLUSIONS: Nitric oxide releasing neurons may play an important contributory role in regulating ocular blood flow.

Animals↗
PubMed1998

Role of the endothelium in modulating functional responses of isolated bovine anterior ciliary arteries to vasoconstrictor agonists.

BACKGROUND/AIMS: Endothelium dependent vasodilatation is an important regulator of blood flow to the eye but its role has not been investigated in vessels supplying the ciliary body. This study assessed the role of the endothelium in modulating vasoconstrictor responses of the intraocular bovine anterior ciliary artery. METHODS: Bovine anterior ciliary arteries (n = 33) were mounted in a myograph, containing physiological salt solution at 37 degrees C, for isometric force measurement. Cumulative concentration-response curves were obtained to the constrictor agonists 5-hydroxytryptamine (5-HT), noradrenaline, phenylephrine, prostaglandin, F2 alpha, endothelin-1, and KCl in both endothelium intact and denuded arteries. RESULTS: All vasoconstrictors produced sustained contractile responses which were unaffected by the removal of the endothelium. Responses to 5-HT were also unaffected by inhibition of nitric oxide synthase. CONCLUSION: These results indicate that neither agonist stimulated nor basal release of nitric oxide from the endothelium modulates responses to vasoconstrictor agonists in the isolated bovine anterior ciliary artery when measured in a no flow isometric system.

Animals↗
PubMed1998

Aetiology, pathogenesis, and pathology of cervical neoplasia.

Early epidemiological studies of cervical neoplasia suggested a causal relation with sexual activity and human papillomaviruses (HPVs) have emerged as prime suspects as venerally transmitted carcinogens. HPVs fall into two broad camps: low risk types, associated with cervical condylomas and CIN 1; and high risk types (mostly 16 and 18), found in 50-80% of CIN 2 and CIN 3 lesions, and 90% of cancers. This association with cancer is very strong, with odds ratios of > 15 (often much higher) in case-control studies that are methodologically sound. An infrequently detected third group of intermediate risk type HPVs is associated with all grades of CIN and occasionally with cancers. HPVs have also been detected in a wide range of asymptomatic controls, indicating that other events are required for development of neoplasia such as viral persistence and/or altered expression of viral genes, often following integration of the viral genome. This leaves the two major viral oncogenes, E6 and E7, directly coupled to viral enhancers and promoters, allowing their continued expression after integration. High risk HPV E7 proteins bind and inactivate the Rb protein, whereas E6 proteins bind p53 and direct its rapid degradation. A range of putative cofactors has been implicated in progression: HLA type, immunosuppression, sex steroid hormones, and smoking; most of these cofactors appear to influence progression to CIN 3. The natural history includes progression to CIN 3 in 10% of CIN 1 and 20% of CIN 2 cases, whereas at least 12% of CIN 3 cases progress to invasive carcinoma. Cervical glandular intraepithelial neoplasia (CGIN) often coexists with squamous CIN, and the premalignant potential of high grade CGIN is not in doubt, but the natural history of low grade CGIN remains uncertain. A high proportion of CGIN lesions and adenocarcinomas are HPV positive, and HPV18 has been implicated more in glandular than in squamous lesions. A strong clinical case for the application of HPV typing of cells recovered from cervical scrapes can be made; however, a rigorous cost-benefit analysis of introducing HPV typing into the cervical screening programme is required. Prophylactic and therapeutic HPV vaccines are under development. This article reviews the aetiology, pathogenesis, and pathology of cervical neoplasia, emphasising the role of HPVs.

Carcinoma, Squamous Cell↗
PubMed1997

The role of computed tomography in the management of ovarian tumours of borderline malignancy.

Ovarian tumours of borderline malignancy are a distinct histological and clinical entity diagnosed in up to 15% of patients presenting with an ovarian neoplasm. Compared with frankly malignant tumours, they have a much better prognosis, present at an earlier age, and the majority are stage 1 at diagnosis. This study reviewed 35 patients with ovarian tumours of borderline malignancy referred to the CRC Medical Oncology Unit at The Christie Hospital over a 9-year period and evaluated the role of diagnostic imaging, in particular, the value of postoperative computed tomography (CT). We conclude that in cases of FIGO stage 1 disease where there is complete macroscopic removal of tumour, there is no need for further routine imaging. If chemotherapy is to be given for patients with more advanced disease, a baseline postoperative abdomino-pelvic CT scan and a post-treatment scan are appropriate investigations.

Adult↗
PubMed1997

Effect of two antiprogestins (mifepristone and onapristone) on endometrial factors of potential importance for implantation.

OBJECTIVE: To investigate the effects of postovulatory administration of antiprogestins on endometrial factors that may be of importance for successful implantation. DESIGN: Ten women were given 200 mg mifepristone and an additional 10 women 400 mg of onapristone 48 hours after the LH surge in urine (LH + 2). MAIN OUTCOME MEASURE(S): Biopsies were assessed for histologic dating and the immunolocalization of [1] leukemia inhibitory factor, [2] 15-hydroxyprostaglandin dehydrogenase, and [3] the cell proliferation marker Ki 67. Hormonal measurements in blood and urine were used to monitor the effects on the ovarian cycle. Glycodelin (placental protein 14) concentrations were measured in blood taken on LH + 12. RESULT(S): Treatment with antiprogestins retarded the development of secretory changes without affecting the length of the luteal phase. In addition, there was reduced immunostaining for 15-hydroxyprostaglandin dehydrogenase within glands and a significant reduction in serum levels of glycodelin. Reduced immunostaining for leukemia inhibitory factor also was apparent within glands in biopsies taken on LH + 6 of the treatment cycle. Increased Ki 67 immunostaining was observed on both cycle days after treatment, consistent with P antagonism. CONCLUSION(S): Administration of mifepristone and onapristone adversely affects uterine receptivity. This adds further evidence to support their potential as a method of postovulatory fertility control.

Abortifacient Agents, Steroidal↗