Development of an isolated, pulsatile blood-perfused rat lung model for evaluating the preserved lung functions

The purpose of this study was to develop an isolated, pulsatile blood-perfused rat lung model that allows us to evaluate the preserved lung functions. Lungs isolated from Sprague-Dawley rats, were perfused with venous whole blood by either a pulsatile or constant flow. The effuent was continuously deoxygenated with a 95% N₂/5% CO₂ gas mixture. Airway resistance, lung compliance, elastic work, flow resistive work, pulmonary vascular resistance, and blood gas analysis were assessed. Pressor responses toN ^G -monomethyl-l-arginine (l-NMMA) were compared between pulsatile and constant blood flow. At a flow of 0.1 ml/g body weight/min, pulsatile perfusion allowed for stable perfusion at least for 2h (mean 162.5±15.1 min) with stable aerodynamic and hemodynamic variables including blood gas tensions, whereas constant perfusion resulted in immediate lung failure. Whenl-NMMA was added to the perfusate, the mean pulmonary artery pressure did not show any change in the constant flow (6.0±2.6% increase), but did show a significant increase in the pulsatile flow (45±11% increase). Pulsatile blood flow reduced the pulmonary vascular resistance relative to the constant flow and allowed for a 2-h perfusion period to evaluate the lung function. The vasorelaxant mechanism in the pulsatile perfusion is related in part to the endothelial-dependent relaxation observed in the nitric oxide pathway. Presented in part at the 79th, Annual Clinical Congress of the American College of Surgeons (ACS) held in San Francisco, CA USA, 1993.     

Comparison of selective media for isolation of Campylobacter jejuni/coli

A comparison of Skirrow's, Butzler's, Blaser's, Campy-BAP and Preston media for Campylobacter spp was made using human, animal and environmental specimens. Butzler's medium gave the lowest isolation rate and Preston medium, which was the most selective, the highest isolation rate. Enrichment culture using Preston enrichment broth gave a higher isolation rate than direct plating onto Preston medium.     

Meningioma presenting as an intraoral mass in a patient with neurofibromatosis type 1

A 77-year-old woman with neurofibromatosis type 1 presented with ill-fitting dentures due to intraoral extension of a right temporal fossa mass. Computed tomographic scanning demonstrated that the masticator space mass bowed the zygomatic arch and remodeled the lateral orbit and maxillary sinus walls, findings that were consistent with the clinical diagnosis of a neurofibroma with possible malignant transformation. However, light microscopic, immunohistochemical, and ultrastructural examination of tissue from an incisional biopsy specimen were diagnostic of meningioma. This case illustrates that the clinicopathologic differential diagnosis of an enlarging mass in patient with neurofibromatosis should include sporadic, unrelated neoplasms as well as tumors known to be associated with the syndrome.     

The early development of the sheep trophoblast and the involvement of cell death

During the period of rapid elongation prior to the initiation of placental attachment (days 12–16 of gestation), the ovine blastocyst consists of a single layer (primarily) of roughly cuboidal trophoblastic cells with an inner lining of flattened endodermal cells. Well-developed spot desmosomes link the adjacent cell borders in both the trophoblastic and endodermal layers. The trophoblastic cells contain acid phosphatase-positive, lysosomelike organelles, the mean diameter of which increases greatly between days 12 and 16 and whose contents vary during development. Also during the developmental period studied, trophoblast cells accumulate lipid; and periodic acid-Schiff-positive binucleate cells appear within the trophoblast layer. A consistent observation throughout the 5 days of rapid growth and differentiation of the blastocyst was the death and disintegration of some trophoblast cells. These disintegrating cells are usually singly dispersed within the trophoblast, although occasionally groups of four or five are observed. The cell death may indicate overall remodelling of the blastocyst, or the cells may represent genetically deficient cells which are unable to respond to the appropriate signal to differentiate.     

Frataxin is reduced in Friedreich ataxia patients and is associated with mitochondrial membranes

Friedreich ataxia is a progressive neurodegenerative disorder caused by loss of function mutations in the frataxin gene. In order to unravel frataxin function we developed monoclonal antibodies raised against different regions of the protein. These antibodies detect a processed 18 kDa protein in various human and mouse tissues and cell lines that is severely reduced in Friedreich ataxia patients. By immunocytofluorescence and immunocytoelectron microscopy we show that frataxin is located in mitochondria, associated with the mitochondrial membranes and crests. Analysis of cellular localization of various truncated forms of frataxin expressed in cultured cells and evidence of removal of an N-terminal epitope during protein maturation demonstrated that the mitochondrial targetting sequence is encoded by the first 20 amino acids. Given the shared clinical features between Friedreich ataxia, vitamin E deficiency and some mitochondriopathies, our data suggest that a reduction in frataxin results in oxidative damage.      

Dithiothreitol prevents age-associated decrease in oocyte/conceptus viability in vitro

The present study was designed to ascertain whether the negative effects on reproductive potential of post-ovulatory ageing in vitro of oocytes can be prevented by antioxidant therapy. Mouse metaphase II (MII) oocytes were aged in vitro for 12 h prior to insemination in the presence of varying concentrations of L-ascorbic acid, 6-methoxy- 2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), L-cystine dihydrochloride, ethylenediaminetetraacetic acid (EDTA), beta- mercaptoethanol and DL-dithiothreitol (DTT). In-vitro ageing of oocytes was associated with lower fertilization rate, higher proportion of concepti exhibiting cellular fragmentation at 24 h post-insemination and lower percentage of concepti reaching the blastocyst stage. Ascorbic acid, Trolox and EDTA had no effect on cellular fragmentation or potential of oocytes for development. However, the probability of an oocyte reaching the blastocyst stage was decreased (P < or = or = 0.05) in oocytes incubated in the presence of L-cystine (50 and 500 microM) and beta-mercaptoethanol (5, 50 and 500 microM) when compared to control aged oocytes. Age-associated cellular fragmentation at 24 h post-insemination was partially prevented (P < or = 0.05) by incubating oocytes in the presence of beta-mercaptoethanol (500 microM). DTT (50 and 500 microM) increased (P < or = 0.05) fertilization rate and number of cells at 81 h post-insemination to levels similar to those exhibited by control oocytes. Furthermore, both age-associated fragmentation at 24 h post-insemination (P < or = 0.05) and decreased potential of oocytes for development to the blastocyst stage (P < or = 0.05) were prevented, at least in part, by culturing oocytes in the presence of DTT (50 microM). Although the mechanism by which DTT exerts its beneficial effects on aged oocytes remains to be elucidated, it may protect oocytes by preventing oxidation of free thiol groups and/or altering a redox-independent signalling pathway that mediates cellular fragmentation and death.      

Y chromosome microdeletions, in azoospermic or near-azoospermic subjects, are located in the AZFc (DAZ) subregion

Submicroscopic deletions of the Y chromosome and polymorphisms of the androgen receptor (AR) gene in the X chromosome have been observed in men with defective spermatogenesis. To further define the subregions/genes in the Y chromosome causing male infertility and its relationship to polymorphisms of the AR polyglutamine tract, we screened the genomic DNA of 202 subfertile males and 101 healthy fertile controls of predominantly Chinese ethnic origin. Y microdeletions were examined with 16 sequence-tagged site (STS) probes, including the RBM and DAZ genes, spanning the AZFb and AZFc subregions of Yq11, and related to the size of trinucleotide repeat encoding the AR polyglutamine tract. Y microdeletions were detected and confirmed in three out of 44 (6.8%) of azoospermic and three out of 86 (3.5%) severely oligozoospermic patients. No deletions were detected in any of the patients with sperm counts of >0.5 x 10(6)/ml, nor in any of the 101 fertile controls. All six affected patients had almost contiguous Y microdeletions spanning the entire AZFc region including the DAZ gene. The AZFb region, containing the RBM1 gene, was intact in five of the six subjects. Y deletions were not found in those with long AR polyglutamine tracts. Our study, the first in a Chinese population, suggest a cause and effect relationship between Y microdeletions in the AZFc region (possibly DAZ), and azoospermia or near-azoospermia. Y microdeletions and long AR polyglutamine tracts appear to be independent contributors to male infertility.