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Biomedical subjects

P Rooney

Publications and source records attributed to P Rooney.

At least 19 recordsLinked to original sources
PubMed1999

Osteoarthritic cartilage loses its ability to remain avascular.

OBJECTIVE: To determine whether human osteoarthritic (OA) cartilage loses its ability to remain avascular when placed into the in-vivo model of angiogenesis, the chick embryo chorio-allantoic membrane (CAM), and to determine specific changes that occur in the cartilage matrix when the cartilage is exposed to an active vasculature. DESIGN: Articular cartilage from OA and non-OA joints was grafted onto the CAM for up to 5 days before fixing and processing for histological, histochemical and immunological examination for specific changes in proteoglycan and collagen. RESULTS: OA cartilage, but not non-OA cartilage, showed invasion of its matrix by blood vessels from the CAM to various extents. Associated with these blood vessels was a loss of staining for proteoglycans and cartilage specific glycosaminoglycans (GAG). A deposition of collagen types I and X was also visualized around the invasive vessels. CONCLUSIONS: OA cartilage loses or has already lost its ability to remain avascular when placed onto the chick CAM. Changes occur in the matrix around the invasive blood vessels, specifically a loss of proteoglycan and GAG, and the deposition of new collagen types, notably I and X.

Aged↗
PubMed1998

Relative paucity of genes causing inviability in hybrids between Drosophila melanogaster and D. simulans.

Using deficiencies from Drosophila melanogaster, we looked for genomic regions in the sister species D. simulans that could cause lethality when hemizygous on a hybrid genetic background. Such genotypes allow hemizygous genes from one species to interact with heterozygous genes from other species and may correspond to the kinds of genotypes causing Haldane's rule, the observation that if only one gender is sterile or inviable in species hybrids, it is nearly always the heterogametic sex. A survey of roughly 50% of the D. simulans genome (114 chromosome regions) revealed only four regions causing hybrid lethality and five causing severe reductions in hybrid viability. However, the viability of all of these genotypes was at least partially restored by rearing hybrids at lower temperature or using different genetic backgrounds from D. simulans. We therefore detected no D. simulans chromosome regions causing unconditional hybrid lethality, although several regions were shown to be deleterious under most tested temperatures and genetic backgrounds. The relative paucity of "inviability genes" supports the idea, suggested by work on other species, that hybrid inviability between closely related species might be caused by interactions among relatively few genes, while hybrid sterility may involve many more loci.

Animals↗
PubMed1997

Early-response gene signalling is induced by angiogenic oligosaccharides of hyaluronan in endothelial cells. Inhibition by non-angiogenic, high-molecular-weight hyaluronan.

The degradation products of hyaluronan are known to stimulate endothelial-cell proliferation and to promote neovascularization associated with angiogenesis, whilst native high-molecular-weight hyaluronan is inhibitory to these processes. To investigate the cellular signalling pathways coupled to hyaluronan-induced responses in angiogenesis, we have analyzed early-response gene expression in vitro, in cultured bovine aortic endothelial cells. Angiogenic oligosaccharides of hyaluronan induced rapid transient up-regulation of the immediate early genes c-fos, c-jun, jun-B, Krox-20 and Krox-24. In contrast, native hyaluronan when used alone failed to elicit a significant change in expression of any of the genes tested, and when used in combination with angiogenic oligosaccharides of hyaluronan, gave a dose-dependent inhibition of induced gene expression. However, prior addition of angiogenic hyaluronan, as little as one minute before addition of high-molecular-weight hyaluronan, abrogated this inhibition, suggesting that positive or negative responses associated with hyaluronan signalling are integrated at a very early stage following receptor binding. Conversely, prior addition of high-molecular-weight hyaluronan led to an irreversible block in gene expression and proliferative response. These data are consistent with native hyaluronan antagonizing the angiogenic response in part by blocking a signalling cascade at or immediately following ligand-receptor interaction. Finally, we demonstrated that chronic exposure to oligosaccharides of hyaluronan is essential for cell proliferation, indicating that short-term immediate early-gene signalling is insufficient to elicit the proliferation of endothelial cells.

Animals↗
PubMed1997

Intrinsic control of vascularization in developing cartilage rudiments.

The vascularization of developing cartilage rudiments is temporally and spatially defined. By using an in vivo angiogenesis model, the chorioallantoic membrane (CAM) of the chick embryo and chick embryo cartilage rudiments, we conclude that the factors controlling the vascular invasion of cartilage rudiments are intrinsic. Intact rudiments, separate hypertrophic zones and separate rounded cell zones, when grafted onto the CAM, become vascularized in the same temporal and spatial manner as occurs in ovo. When grown as organ cultures prior to CAM grafting, rudiments still become vascularized in the same temporal and spatial manner. The integrity of the extracellular matrix and the presence of the periosteum are two physical factors regulating the control of vascularization. Removal of the periosteum from hypertrophic regions caused a cessation of the invasion. Insults to the matrix via brief enzymatic degradation of extracellular matrix components resulted in invasion and erosion of rounded cell zones at an earlier time than is ordinarily seen both in ovo and on the CAM.

Animals↗
PubMed1996

Extraparotid Warthin's tumor: clinical manifestations, challenges, and controversies.

Extraparotid Warthin's tumors continue to challenge the head and neck surgeon's diagnostic and therapeutic skills. A series of six extraporotid Warthin's tumors are presented to illustrate the need to keep a high index of suspicion for this lesion in the workup of cystic masses involving cervical levels II and III or in the event of a concomitant neck mass and a parotid Warthin's tumor. Discussion of the debate surrounding the embryogenesis and histogenesis of extraparotid Warthin's tumors follows. Clinical guidelines are suggested for the diagnosis, treatment, and follow-up of patients with extraparotid Warthin's tumors.

Adenolymphoma↗
PubMed1996

Thoracic anaesthesia.

The uniqueness of thoracic anaesthesia is that it is conducted concurrently with operative surgery on, or in the vicinity of, those very organs which are receiving the anaesthetic gases. Although some procedures do not directly involve the lungs, e.g. oesophageal surgery, all consist of breaches in the integrity of one or both pleural cavities, whether in open thoracotomies or thoracoscopic procedures. Thus, hypoxia and hypercarbia are a constant threat. This is compounded by the fact that the patients are frequently elderly with chronic health problems and, consequently, poor anaesthetic risks. In view of this, an overview of respiratory anatomy and physiology will be given, followed by consideration of some of the anaesthetic strategies applied to meet the particular challenges of this surgical specialty.

Anesthesia, Inhalation↗
PubMed1996

Essentials of anaesthesia for opthalmic surgery.

Unfortunately the eye is prone to very many pathological conditions, either congenital or acquired. Thankfully, all but the most extreme are amenable to surgical treatment. The anaesthetist's role in this process is, principally, to present the surgeon with an eye which is operable. How this is done will be considered in the latter part of this article. However, as in all areas of anaesthetic practice, a detailed knowledge of anatomy and physiology is essential. This aspect will be dealt with first.

Anesthesia↗
PubMed1996

Anaesthesia for cardiac surgery.

Perhaps no form of surgery is as emotive as that on the heart. From ancient times, seen as the seat of the emotions, the heart has been recognised as a vital if, at times, mysterious organ. Its grip on the imagination of primitive peoples is exemplified in the extreme by the climax of the human sacrificial ceremonies carried out by the Aztec and Inca peoples of Mexico and Peru: the holding aloft by the priest of the victim's still-beating heart. Nowadays, although we might congratulate ourselves on the heights of civilization which we have attained, it is salutary to consider that such cultural achievements are but a veneer through which primordial emotions frequently burst. As professional nurses, however, while appreciating the emotions of our patients and relatives with regard to cardiac surgery, we need to exercise sufficient detachment so that effective care may be delivered. This article will discuss cardiac anaesthesia generally, but will not touch on the specialised subjects of transplantation. It also accepts that techniques and drug regimes vary from centre to centre.

Anesthesia↗
PubMed1995

The role of hyaluronan in tumour neovascularization (review).

Tumour growth and metastasis are totally dependant upon neovascularization. The target cell for tumour neovascularization is the blood-vessel endothelial cell, and specific angiogenic molecules produced or induced by the tumour are believed to initiate the process. In this report, we review one of these angiogenic molecules, the glycosaminoglycan hyaluronan (HA), which appears to have differing roles in neovascularization depending on its molecular mass. High-molecular-mass HA is anti-angiogenic whereas oligosaccharides of HA, of specific size, actively stimulate endothelial-cell proliferation and migration, 2 of the key events associated with neovascularization, and induce angiogenesis in vivo. We provide details of the action of HA oligosaccharides on endothelial cells, from binding to cell-surface receptors, through activation of signal transduction pathways and gene expression to protein synthesis, cell proliferation and cell migration. We also suggest a model to account for HA of differing molecular mass being present, at different locations, within a single tumour and how this HA aids both general tumour growth and tumour metastasis.

Cell Division↗
PubMed1995

Dexamethasone treatment of lipopolysaccharide-induced meningitis in rabbits that mimics magnification of inflammation following antibiotic therapy.

The objective of adjunct anti-inflammatory therapy of bacterial meningitis is the containment of heightened inflammation caused by lysis of bacteria by antibiotics. This can be modelled by giving two consecutive intra-cisternal injections of lipopolysaccharide (LPS) to rabbits, the first at 0 h to induce inflammation to mimic that occurring during the proliferation of bacteria in the cerebrospinal fluid (CSF), and the second at 6 h to mimic inflammation subsequent to antibiotic-induced bacterial lysis. Injection of 2.5 ng of LPS induced pleocytosis at 4 h which was preceded by a peak of tumour necrosis factor (TNF) activity at 2 h. A subsequent injection of 25 ng of LPS at 6 h induced second peaks of pleocytosis and CSF TNF. Dexamethasone (1.5 mg/kg, i.v.) administered 15 min or 1 h before the second injection of LPS tended only to reduce CSF TNF, but effectively prohibited further pleocytosis. Brain TNF alpha mRNA levels were unchanged at 6 and 7 h after LPS injection, and were unaffected by dexamethasone. These results indicate that the subarachnoid space is distinct from the general circulation in that the TNF-producing cells present do not display a hypo-responsive state towards LPS as occurs when LPS is injected systemically. Furthermore, dexamethasone is able to attenuate the secondary inflammatory response resulting from a second LPS injection without eliminating a second peak of TNF activity.

Animals↗
PubMed1995

Essentials of obstetric anaesthesia.

Obstetric anaesthesia is unique in that there is a "double patient" for whom the anaesthetic staff, medical and nursing, have responsibility. The question must also be asked, "Why anaesthesia in obstetrics anyway?" There is one main reason, with two applications-pain relief for both labour and for operative delivery. It is, therefore, professionally prudent to be aware of the special physical challenges presented.

Anesthesia, Obstetrical↗
PubMed1995

Anaesthesia for neurosurgery--essentials of anaesthesia.

Paul Rooney continues his series of articles on anaesthetics. In approaching the topic of anaesthesia for neurosurgery he is aware of the need for a clear understanding of basic anatomy and physiology of the central nervous system.

Anesthesia↗
PubMed1994

Application of angiogenic oligosaccharides of hyaluronan increases blood vessel numbers in rat skin.

Angiogenic oligosaccharides of hyaluronan were applied to the backs of young, adult male rats and the number of blood vessels, within a depth of 136 microns beneath the base of the epidermis, were evaluated. Application of hyaluronan oligosaccharides significantly increased the mean number of blood vessels/mm skin length in six of 11 treated rats when compared with controls. Application of radiolabeled hyaluronan oligosaccharides to skin of one rat demonstrated a penetration to a depth of approximately 800 microns, suggesting that the blood vessels beneath the epidermis would be exposed to the hyaluronan. Hyaluronan has previously been shown to stimulate endothelial cell proliferation; we demonstrate here that these hyaluronan oligosaccharides also specifically stimulate endothelial cell migration. This action of hyaluronan oligosaccharides may prove useful in retarding blood vessel paucity and degeneration observed during the ageing process and following radiotherapy.

Animals↗
PubMed1994

Adult intubation for beginners.

The UKCC's 'Scope of Professional Practice' validly points out that, 'Practice takes place in a context of continuing change and development' partly 'as a result of new approaches to professional practice'. Consequently, demands are made on educational institutions to prepare professionals for new practice. One of the new skills, which is now being taught to nurses on the Anaesthetic Nursing Course at the Eastern Area College, is that of endotracheal intubation. Bearing in mind the all-important proviso that 'As a registered nurse, midwife or health visitor, you are personally accountable for your practice', it is essential that post registration education 'equips practitioners with additional and more specialist skills necessary to meet the special needs of patients and clients'. This article is therefore designed as an introduction to the basic rationale, anatomy and procedural skills necessary for safe intubation.

Humans↗