Skewed oligomers and origins of replication

In pigs, induction of embryonic degeneration, by exogenous oestrogens given early in gestation, has been long recognised. However, the underlying mechanisms responsible for this degeneration remain unclear. The present study was conducted to determine whether oestrogen-induced early porcine embryonic mortality was associated with changes in the levels of tumour necrosis factor-alpha (TNF-alpha) messenger RNA in the uterine endometrium. Prepubertal gilts were induced into oestrus with PG600 and artificially inseminated at their second natural oestrus and again 24 h later. After insemination, gilts were randomly assigned to treatment and given 0.5 ml intramuscular injections of either oestradiol valerate (10 mg ml-1) or corn oil on day 9 and 10 of gestation. The gilts were slaughtered on day 12, 15 or 18 of gestation. The reproductive tract was removed from each gilt and the uterine horns were flushed to check for the presence and integrity of embryos. Samples of uterine endometrial tissues were collected, snap-frozen in liquid nitrogen and stored at -80 degrees C. Total cellular RNA was isolated from frozen tissues using a guanidine isothiocyanate-cesium chloride method. The abundance of TNF-alpha messenger RNA was determined by Northern blot hybridisation analysis. Treatment of pregnant gilts with oestrogen resulted in severe fragmentation of embryos on days 15 (2/3) and 18 (2/2), confirming the embryocidal effect of exogenous oestrogen. Uterine TNF-alpha messenger RNA level was elevated in oestrogen-treated gilts compared with controls (P < 0.05). This observation of an association between increased levels of TNF-alpha mRNA in the uterus and embryonic degeneration in oestrogen-treated gilts suggests that TNF-alpha may be involved in mediating oestrogen-induced early embryonic mortality in the pig.     

Structure and interactions of fully hydrated dioleoylphosphatidylcholine bilayers

This study focuses on dioleoylphosphatidylcholine (DOPC) bilayers near full hydration. Volumetric data and high-resolution synchrotron x-ray data are used in a method that compares DOPC with well determined gel phase dipalmitoylphosphatidylcholine (DPPC). The key structural quantity obtained is fully hydrated area/lipid A0 = 72.2 +/- 1.1 A2 at 30 degrees C, from which other quantities such as thickness of the bilayer are obtained. Data for samples over osmotic pressures from 0 to 56 atmospheres give an estimate for the area compressibility of KA = 188 dyn/cm. Obtaining the continuous scattering transform and electron density profiles requires correction for liquid crystal fluctuations. Quantitation of these fluctuations opens an experimental window on the fluctuation pressure, the primary repulsive interaction near full hydration. The fluctuation pressure decays exponentially with water spacing, in agreement with analytical results for soft confinement. However, the ratio of decay length lambda(fl) = 5.8 A to hydration pressure decay length lambda = 2.2 A is significantly larger than the value of 2 predicted by analytical theory and close to the ratio obtained in recent simulations. We also obtain the traditional osmotic pressure versus water spacing data. Our analysis of these data shows that estimates of the Hamaker parameter H and the bending modulus Kc are strongly coupled.     

Effects of low-dose morphine on gastric emptying in healthy volunteers

BACKGROUND: Type 2 diabetes mellitus is a major and increasing cause of morbidity and early mortality among the Aboriginal population of northern Australia. Due to differing social, dietary and probably metabolic factors, management needs differ from the mainstream Australian diabetic population. OBJECTIVE: This paper concentrates on the options for oral therapy in the control of glycaemia, taking into account various current guidelines and recent trials of oral antihyperglycaemic therapy, and the specific metabolic and clinical associations with type 2 diabetes mellitus in this population. DISCUSSION: In the abscence of specific contraindications, and in variance with some present guidelines, the evidence suggests that initial therapy with metformin rather than the sulphonylureas is likely to provide greater clinical benefit, and have a greater margin of safety.     

Medical Editors Trial Amnesty

Epstein-Barr virus-associated smooth muscle proliferations have been reported in immunosuppressed patients with acquired immunodeficiency syndrome and after organ transplantation. We report here a case of a histologically benign case arising in a 48-year-old male who had received immunosuppressive therapy 4 years earlier, after cardiac transplantation. In the necropsy performed for unrelated reasons, an incidental left intramyocardial tumor was discovered. The presence of Epstein-Barr virus was confirmed by EBER-1 in situ hybridization and polymerase chain reaction. To the best of our knowledge, this is the first case of an Epstein-Barr virus-associated smooth muscle proliferation arising in the heart after cardiac transplantation and should be added to the potential complications of this kind of procedure.     

Asymptomatic carotid endarterectomy. Patient and surgeon selection

PURPOSE: The detection of an infraclinical primary by tonsillectomy in case of cervical lymph node of an epidermoid carcinoma with unknown primary after a radical neck dissection, allows avoiding irradiation of the normal larynx. The aim of this study is to quantify the rate of tonsil primary to justify this procedure. METHODS AND MATERIALS: From 1969 to 1992, 87 patients had a tonsillectomy as part of the workup for cervical nodal metastasis of an epidermoid carcinoma with unknown primary. The mean age was 57 years (range: 39-75 years) and the sex ratio was 8.6. Sixty-seven patients had a single cervical adenopathy (17 N1, 30 N2a, 5 N3, 15 Nx), and 20 patients multiple cervical adenopathies (17 N2b, 3 N2c). The treatments included always an irradiation to the node areas (50 Gy), and to the pharyngolarynx in case of normal tonsil (50 Gy), or to the tonsil if it was the primary (50 Gy with a brachytherapy boost of 20-25 Gy). In this last case, the larynx could be protected. RESULTS: Tonsillectomy never induced specific complication. Out of 87 patients, 26% had a tonsil primary. There was not specific histological differentiation in this group. In the 67 patients with a single cervical adenopathy, 31% had a tonsil primary (6 N1, 7 N2, 1 N3, 7 Nx). It was a subdigastric adenopathy in 38%, a submandibular in 28% and a midjugulocarotidian in 23%. Among the 17 patients N2b, none had a tonsil primary. In the three patients N2c, two presented a tonsil carcinoma (two subdigastric nodes). CONCLUSION: Tonsillectomy allows avoiding irradiation of normal larynx in 26% of patients who have a cervical lymph node with unknown primary. It should be performed in case of a single node of the subdigastric, midjugulocarotidian or submandibular area or bilateral subdigastric adenopathies.     

Corticotropin-releasing hormone and proopiomelanocortin-derived peptides are present in human myometrium

CRH and POMC-derived peptides are produced at a number of intrauterine sites in both the nonpregnant and pregnant states. It is hypothesized that CRH and POMC-derived peptides may be produced locally by the uterus to modulate myometrial contractility. This study has examined the distribution of these peptides in human uterine tissue during the ovulatory cycle and pregnancy. The immunoperoxidase staining method was used to localize CRH and POMC-derived peptides: ACTH, beta-endorphin, and alphaMSH. Immunoreactive (IR-) CRH and IR-POMC-derived peptides, beta-endorphin and alphaMSH, were observed in the myometrial smooth muscle, vascular smooth muscle, endometrial glandular epithelium, and luminal epithelium of the nonpregnant uterus (n = 17). Staining for IR-CRH did not change during the cycle from the proliferative (n = 8) to the secretory phases (n = 9). Conversely, staining for IR-beta-endorphin and IR-alphaMSH was only observed during the secretory phase of the cycle (n = 9). In uterine tissue obtained from pregnant women (n = 20) IR-CRH was present in the myometrial smooth muscle, vascular smooth muscle, decidua, and glandular epithelium. IR-POMC-derived peptides were not detectable at any uterine site during pregnancy (n = 20). IR-CRH was measurable in myometrial extracts collected from pregnant women undergoing cesarean section (20.9+/-3.8 ng/g wet wt; n = 7) and from nonpregnant premenopausal women undergoing hysterectomy (7.7+/-2.1 ng/g wet wt; n = 6). IR-CRH concentrations significantly increased with pregnancy. Levels of messenger ribonucleic acid encoding for CRH were examined in nonpregnant (n = 4) and pregnant (n = 10) myometrial smooth muscle and were also significantly increased with pregnancy. This study has demonstrated that levels of CRH and POMC peptide in human uterine tissue change with pregnancy and that CRH is produced locally by myometrial smooth muscle cells. These studies are consistent with the possibility that the CRH peptide has an autocrine/paracrine activity during pregnancy and labor that may be related to the modulation of myometrial contractility.     

Use of a simple light absorbance assay to measure lymphocyte proliferation

The proliferative response of human lymphocytes to stimuli such as foreign histocompatibility antigens or mitogens is generally assessed by measuring the amount of tritiated thymidine which the cells incorporated in culture. In this paper, the possibility of assessing lymphocyte proliferation and viability by an empirical assay, using measurement of light absorbance on a ELISA reader in the yellow wave length (450 nm/air-550 nm/air), has been studied. The correlation of these measurements with a colormetric viability assay using MTS/PMS, with tritiated thymidine incorporation and with trypan blue exclusion viability counting, was determined. The results showed that the light absorbance assay correlated well with cell proliferation during 48-120 hours culture period and with cell viability after a 72 hour period. The MTS/PMS colormetric assay as well as trypan blue exclusion cell counting confirmed that the light absorbance assay was not merely caused by dead cells. This data confirm that the light absorbance assay is sufficiently sensitive to low levels of proliferation to allow detection of such responses at least as effectively as thymidine incorporation. The light absorbance assay procedure avoids the expense, time and hazards associated with scintillation counting, and is simple to perform without the necessity for reagents and preparative steps required by other assays.     

Reduction of restenosis after angioplasty in an atheromatous rabbit model by suicide gene therapy

BACKGROUND: Gene delivery of the thymidine kinase (tk) gene combined with ganciclovir (GCV) limits intimal hyperplasia after abrasion of normal arteries. However, the low efficiency of adenoviral-mediated gene transfer to atherosclerotic arteries has raised concerns about the applicability of this strategy to the prevention of restenosis. METHODS AND RESULTS: A replication-defective adenoviral vector expressing tk (Ad-RSVtk) demonstrated selective toxicity toward GCV-treated arterial smooth muscle cells, with oligonucleolytic cleavage suggesting apoptosis. In vivo, after demonstration of tk expression after Ad-RSVtk delivery, the combination of Ad-RSVtk followed by GCV was tested in a rabbit model of angioplasty of atheromatous iliac arteries. Angioplasty (8 atm, 20 minutes) was performed by use of a hydrogel balloon coated with Ad-RSVtk (4x10(9) plaque forming units). GCV was infused (25 mg.kg(-1) I.V. BID) from days 2 through 7 after angioplasty in 8 of 12 rabbits. Four weeks later, morphometric analysis demonstrated a reduced intima-to-media ratio in the group receiving combination therapy compared with Ad-RSVtk alone (3.0+/-1.2 versus 5.2+/-0.5, P<.018). GCV per se had no effect on intimal hyperplasia after arterial injury. CONCLUSIONS: In vitro, Ad-RSVtk demonstrates selective toxicity toward GCV-treated arterial smooth muscle cells involving apoptosis. In vivo, GCV conditions reduction of neointimal formation after percutaneous delivery of Ad-RSVtk during angioplasty of atheromatous arteries.     

Studies of the cellular mechanisms underlying the vasorelaxant effects of rutaecarpine, a bioactive component extracted from an herbal drug

We conducted studies to investigate the nature and underlying mechanisms of the vascular effects of rutaecarpine (Rut), an alkaloid isolated from the Chinese herbal drug Evodia rutaecarpa. By using largely the effects on phenylephrine (PE)-induced contraction in the isolated rat aorta as the experimental index and by comparison with several known vascular muscle relaxants such as acetylcholine (ACh), histamine, and A23187, Rut relaxed PE-precontracted aorta in concentration-(10(-7)-10(-4) M) and endothelium-dependent manners. Studies with appropriate antagonists indicated that this was coupled to nitric oxide (NO) and guanylyl cyclase. Extracellular Ca2+ removal and treatment with the intracellular Ca2+ antagonist, 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8), suggested that influx of extracellular Ca2+ was the major factor contributing to the action of Rut. Pertussis toxin suppressed the relaxation potency of histamine but had no effects on the actions of Rut. NaF, the G proteins activator, attenuated the actions of ACh, but only minimally affected Na-NP, A23187, and Rut. 1-[6-{[17 beta-3-methoxyestra-1,2,3(10)-trien-17-yl]amino} hexyl]-1H-pyrrole-2,5-dione (U73122), the phospholipase C inhibitor, again suppressed the actions of ACh but had few effects on A23187 and Rut. Taken together, these results suggest that these vasorelaxants had different cellular mechanisms and that neither pertussis toxin-sensitive Gi protein, other G proteins, nor phospholipase C activation was involved in the cellular response to rutaecarpine.     

Three-dimensional contrast-enhanced magnetic resonance angiography of the thoracic vasculature

Magnetic resonance angiography (MRA) has become a useful non-invasive imaging technique for the assessment of vascular disease. Due to limitations such as respiratory motion artefacts, saturations problems, and long acquisition times, applications of MRA in the thorax have largely been restricted to imaging of the aorta. The recent introduction of breath-hold three-dimensional (3D) contrast-enhanced MRA promises not only to enhance conventional MR protocols for aortic imaging, but to extend the clinical indications of MRI to diseases affecting other vascular structures of the thorax, most notably the pulmonary arteries. This article describes the technical aspects of contrast-enhanced 3D MRA and reviews existing and potential future clinical applications.