FUNCTIONAL ROLE OF CARDIAC PRESYNAPTIC α2-ADRENORECEPTORS IN THE BRADYCARDIA OF α-ADRENORECEPTOR AGONISTS IN PENTOBARBITONE- AND URETHANE-ANAESTHETIZED NORMOTENSIVE RATS

• 1 The relative potencies of 6 α-adrenoreceptor agonists, with differing physicochemical properties, at cardiac presynaptic α-adrenoreceptors were determined by measuring their ability to reduce the tachycardia produced by stimulation of the cardiac sympathetic nerves in pithed rats. The compounds studied were clonidine, B-HT 933 (azepexole), oxymetazoline, St 91, naphazoline and DPI.
• 2 The bradycardia produced by the same compounds in bilaterally vagotomized, urethane- or pento-barbitone-anaesthetized normotensive rats were also compared. The relative order of presynaptic potency appeared similar to that observed for the bradycardic activity of the compounds in urethane- and pento-barbitone-anaesthetized rats. In pentobarbitone-anaesthetized rats all compounds evoked a maximal effect of 18–20% reduction in heart rate. In urethane-anaesthetized rats, however, a difference was observed between clonidine and azepexole on the one hand and oxymetazoline, St 91, naphazoline and DPI on the other hand. The former induced a 20–22% reduction in cardiac frequency, whereas the latter diminished heart rate by 10–16% only. In vagotomized, bilaterally adrenalectomized, urethane-anaesthetized rats, clonidine, St 91, naphazoline and azepexole evoked a 25% reduction in heart rate, whereas a 20% reduction was observed for DPI and oxymetazoline.
• 3 A radio-enzymatic determination of plasma catecholamines demonstrated that under urethane-anaesthesia plasma adrenaline concentrations were significantly elevated over the values observed in pentobarbitone-anaesthetized rats. This rise in plasma adrenaline was related to the amount of urethane used. In urethane-anaesthetized, bilaterally adrenalectomized rats, plasma adrenaline was not significantly elevated.
• 4 These findings demonstrate the involvement of cardiac presynaptic α₂-adrenoreceptors in the acute bradycardia, evoked by the α-adrenoreceptor agonist upon intravenous application to pentobarbitone-anaesthetized, normotensive rats. In urethane-anaesthetized rats, however, the functional role of the cardiac presynaptic α₂-adrenoreceptors may be obscured as a result of the high plasma adrenaline levels observed in these animals.

     

IMPAIRMENT BY NIFEDIPINE OF VASOPRESSOR RESPONSES TO STIMULATION OF POSTSYNAPTIC α2-ADRENORECEPTORS IN GANGLION-BLOCKED RABBITS. FURTHER EVIDENCE FOR THE SELECTIVE INHIBITION OF POSTSYNAPTIC α2-ADRENORECEPTOR-INDUCED PRESSOR RESPONSES BY CALCIUM ANTAGONISTS

• 1 After ganglionic blockade and bilateral vagotomy, vasopressor responses induced by activation of postsynaptic α₁- and α₂-adrenoreceptors were elicited in the intact circulatory system of rabbits.
• 2 The hypertensive effects of the selective stimulating agents methoxamine (α₁-agonist) and B-HT 920 (α₂-agonist) were effectively antagonized by the adrenoreceptor antagonists prazosin and yohimbine, respectively. These findings confirm the existence of two types of postsynaptic α-adrenoreceptors (α₁-and α₂-type) in vascular smooth muscle of rabbits.
• 3 The calcium antagonistic drug nifedipine did not affect the maximal increase in diastolic pressure brought about by methoxamine, whereas it strongly inhibited the hypertensive effects of B-HT 920.
• 4 It is concluded that this confirmation of the selective inhibition of postjunctional α₂-adrenoreceptor-mediated vasopressor responses by a calcium antagonistic drug, such as nifedipine, indicates that this activity constitutes a general phenomenon. This finding supports the hypothesis that an influx of extracellular calcium is necessary for the vasoconstriction mediated by postsynaptic α₂-adrenoreceptors.

     

Tumor recurrence and survival in patients treated for thymomas and thymic squamous cell carcinomas: a retrospective analysis.

PURPOSE: Thymic epithelial tumors (TET) are rare epithelial neoplasms of the thymus with considerable histologic heterogeneity. This retrospective study focused on the correlation of WHO-defined TET histotypes with survival and tumor recurrence in a large cohort of patients receiving different modes of treatment. PATIENTS AND METHODS: Two hundred twenty-eight patients were followed for up to 21 years (median, 60 months; range, 1 to 252 months) after primary surgery. Forty-two patients received adjuvant radiotherapy (mean dose, 53 Gy), and 33 patients received adjuvant chemotherapy. RESULTS: Seventy-six (88%) of 86 patients with WHO type A, AB, and B1 thymomas were treated by surgery alone, with three tumor relapses after 3 to 10 years (median, 3.4 years). Twelve of 67 patients with WHO type B2 and B3 thymomas in Masaoka stages I and II were treated by adjuvant radiotherapy without evidence of tumor recurrence after 1 to 12 years (median, 4 years). Among 75 patients with B2 and B3 thymomas with incomplete resection or a tumor stage III or higher, the recurrence rate was 34% (n = 23) after 0.5 to 17 years (median, 5 years) in patients receiving adjuvant radiochemotherapy, compared to 78% (seven of nine patients) in patients without adjuvant radiochemotherapy. Incomplete tumor resection was associated with a high recurrence rate (65%) and a poor prognosis (P <.01). CONCLUSION: The long-term outcome of TET patients is related to tumor stage, WHO histotype, completeness of surgical removal, and type of treatment. Prospective trials are warranted to formally address the efficacy of adjuvant therapy in the treatment of localized and advanced malignant TETs.     

Neoadjuvant cisplatin plus ifosfamide in patients with stage IIB cervical cancer: a single center phase II study

The objective of this study was to evaluate cisplatin plus ifosfamide as neoadjuvant chemotherapy with regard to toxicity and clinical response in patients with stage IIB cervical cancer. Sixty-eight patients with previously untreated stage IIB cervical cancer were given two cycles of chemotherapy: cisplatin 20 mg m⁻² on Days 1–5, infused over 1 h; ifosfamide 1.2 g m⁻² on Days 1–5 infused over 30 min. Mesna 120 mg m⁻² was administered as a bolus 15 min before ifosfamide, and a continuous infusion, delivering Mesna 1.2 g m⁻², was given subsequently over the next 16 hours. The treatment cycle was repeated on day 21. Responders were then randomized to surgery or radiation therapy. All 68 patients were evaluable for toxicity. Toxicity was found to be acceptable. One patient died at home one month after completion of the second treatment cycle. There was one grade 4 thrombocytopenia. Grade 3 toxicities included anemia in four patients, leucopenia and nausea and vomiting in one patient each. Sixty-two patients were evaluable for response. A clinical response was documented in 44 of the 55 evaluable patients (80%), with 17 complete responses (31%) and 27 partial responses (49%) (95% confidence limits 69%–91%, 19%–43%, and 36%–62% respectively). The intent-to-treat response rate was 64.7%. Twenty-one patients were randomized to surgery and 23 patients to radiation therapy. Amongst the eight patients with a complete clinical response, one patient had a complete pathological response and one patient had residual intra-epithelial neoplasia. The drug combination of cisplatin plus ifosfamide had acceptable toxicity and gave a clinical response rate of 80% in previously untreated patients with stage IIB cervical cancer.     

Effect of the viable-yellow (A(vy)) agouti allele on skin tumorigenesis and humoral hypercalcemia in v-Ha-ras transgenic TGxAC mice

We previously reported that papillomas can arise from the follicular epithelium of v-Ha-ras transgenic TGxAC mice. Since the viable-yellow mutation (A(vy)) of the mouse agouti gene which regulates coat color pigmentation by acting within the micro-environment of the hair follicle has been shown to function as a tumor promoter in the liver, we hypothesized that it may also play a role in TGxAC skin tumorigenesis. Endogenous agouti protein product was detected in the outer root sheath of anagen hair follicles following plucking of the hair shaft, but not in the interfollicular epithelium, in TGxAC mice on an FVB/N genetic background. It was also detected in papillomas from these mice produced by 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment or plucking. Expression of the A(vy) allele in the v-Ha-ras transgenic TGxAC mouse line results in an approximately 2-fold increase in papilloma development compared with controls which did not carry the A(vy) allele following twice-weekly treatment with 1.25, 2.5 or 5.0 microg TPA. In addition, TPA-treated, papilloma-bearing F1 mice which carried the A(vy) allele, but not F1 mice which did not carry the A(vy) allele, exhibited a syndrome of humoral hypercalcemia mediated by parathyroid hormone-related protein (PTHrP) that led to weight loss, hypercalcemia and hypophosphatemia. Thus, we conclude that the A(vy) allele can influence the development of skin tumors and PTHrP-mediated humoral hypercalcemia in v-Ha-ras transgenic TGxAC mice.      

Human metabolism of the proteasome inhibitor bortezomib: identification of circulating metabolites.

Bortezomib [N-(2,3-pyrazine)carbonyl-L-phenylalanine-L-leucine boronic acid] is a potent first-in-class dipeptidyl boronic acid proteasome inhibitor that was approved in May 2003 in the United States for the treatment of patients with relapsed multiple myeloma where the disease is refractory to conventional lines of therapy. Bortezomib binds the proteasome via the boronic acid moiety, and therefore, the presence of this moiety is necessary to achieve proteasome inhibition. Metabolites in plasma obtained from patients receiving a single intravenous dose of bortezomib were identified and characterized by liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Metabolite standards that were synthesized and characterized by LC/MS/MS and high field nuclear magnetic resonance spectroscopy (NMR) were used to confirm metabolite structures. The principal biotransformation pathway observed was oxidative deboronation, most notably to a pair of diastereomeric carbinolamide metabolites. Further metabolism of the leucine and phenylalanine moieties produced tertiary hydroxylated metabolites and a metabolite hydroxylated at the benzylic position, respectively. Conversion of the carbinolamides to the corresponding amide and carboxylic acid was also observed. Human liver microsomes adequately modeled the in vivo metabolism of bortezomib, as the principal circulating metabolites were observed in vitro. Using cDNA-expressed cytochrome P450 isoenzymes, it was determined that several isoforms contributed to the metabolism of bortezomib, including CYP3A4, CYP2C19, CYP1A2, CYP2D6, and CYP2C9. The development of bortezomib has provided an opportunity to describe the metabolism of a novel boronic acid pharmacophore.     

A rare association of synchronous intraductal carcinoma of the breast and invasive carcinoma of ectopic breast tissue of the vulva: case report and literature review

Abstract.   Intra M, Maggioni A, Sonzogni A, De Cicco C, Machado LS, Sagona A, Talakhadze N. A rare association of synchronous intraductal carcinoma of the breast and invasive carcinoma of ectopic breast tissue of the vulva: case report and literature review. Int J Gynecol Cancer 2006; 16(Suppl. 1): 428–433.
Only 17 cases of breast carcinoma arising in vulvar ectopic mammary tissue have been reported. We present a unique case of synchronous pure intraductal carcinoma of the breast (DCIS) and invasive carcinoma of ectopic breast tissue of the vulva. A 53-year-old woman presented with a 2-cm nodule in left labium major of the vulva. A surgical biopsy revealed an invasive carcinoma of ectopic mammary tissue. The mammography showed irregular microcalcifications of the right breast. The patient underwent left hemivulvectomy, bilateral inguinal sentinel lymph node biopsy, and radioguided breast resection (radioguided occult lesion localization) of the microcalcifications. The definitive histology revealed negative inguinal sentinel nodes, no further residual tumor in the vulva, and a high-grade (grade 3) DCIS in the breast. The synchronous occurrence of primary breast carcinoma and ectopic breast tissue carcinoma in the vulva is an extremely rare finding, only once previously being reported and leading to unsolved problems of differential diagnosis. The presence of a pure DCIS of the breast makes this case really unique, definitively confirming the independent primary origin of both mammary tumors. The inguinal sentinel node biopsy avoided a bilateral inguinal dissection.     

人肝癌细胞株VEGF/VEGFR的检测及意义探讨

目的：筛选血管内皮生长因子（vascular endothelial growth factor，VEGF）高表达肝癌细胞株，为进一步研究VEGF在肝癌治疗中的作用提供理论依据。并探讨VEGF受体在肝癌细胞株的表达及意义。方法：ELISA法及Western blot法分别检测人肝癌细胞株培养上清及细胞内VEGF蛋白的表达。免疫细胞化学方法检测VEGFR在人肝癌细胞中的表达。结果：5株肝癌细胞株均见VEGF蛋白表达，其中SMMC-7721的VEGF表达量最高，VEGF特异性受体Fit-1在HepG2、HHCC、SMMC-7721、Bcl-7402见阳性表达，KDR在HepG2、HHCC、Bel-7402、QGY-7701见阳性表达。结论：肝癌细胞株中VEGF表达量不尽一致，VEGF在肝癌发生发展中可能存在自分泌作用方式。     

Determination of malondialdehyde-induced DNA damage in human tissues using an immunoslot blot assay

Malondialdehyde (MDA) is a product of lipid peroxidation and prostaglandin biosynthesis. It is mutagenic and carcinogenic and the major adduct formed by reaction with DNA, a highly fluorescent pyrimidopurinone (M1-dG), has been detected in healthy human liver and leukocyte DNA. Analytical methods used so far for the detection of M1- dG have not been applied to a large number of individuals or variety of samples. Often, only a few microg of DNA from human tissues are available for analysis and a very sensitive assay is needed in order to detect background levels of M1-dG in very small amounts of DNA. In this paper, the development of an immunoslot blot (ISB) assay for the measurement of MI-dG in 1 microg of DNA is described. The limit of detection of the assay is 2.5 adducts per 10(8) bases. A series of human samples were analysed and levels of 5.6-9.5 (n = 8) and 3.1-64.3 (n = 42) of M1-dG per 10(8) normal bases were detected in white blood cell and gastric biopsy DNA, respectively. Results on four human samples were compared with those obtained using an HPLC/32P-post- labelling (HPLC/PPL) method previously developed and indicated a high correlation between M1-dG levels measured by the two assays. The advantages of ISB over other assays including HPLC/PPL, such as the possibility of analysing 1 microg DNA/sample and the fact that it is less time-consuming and laborious, means that it can be more easily used for routine analysis of a large number of samples in biomonitoring studies.