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Biomedical subjects

P G Sullivan

Publications and source records attributed to P G Sullivan.

31 records · Page 2Linked to original sources
PubMed1987

Accidental hypothermia and frost-bite in Antarctica.

Two members of an Australian Antarctic expedition suffered hypothermia and frost-bite when they were stranded onshore after their small boat was swamped. Their efforts at field survival until recovery, six hours later, are described. At rescue one patient was found to have frost-bite and a core temperature of 30 degrees C. He was treated successfully by rapid rewarming in a hot bath. The other victim was considerably less hypothermic and suffered only mild frost-bite. Contrary to expectations the tall thin patient fared much better than the short heavier one. Possible explanations for this difference are discussed.

Adult↗
PubMed1984

An investigation into the benefits of resiting nasoenteric feeding tubes.

Partial nasal obstruction in preterm infants increases the airway resistance. In spite of this, nasal feeding tubes are often used, if only because oral tubes are difficult to secure. A palatal appliance has been devised that maintains the position of oroenteric feeding tube(s) and is not associated with local complications. In order to assess the effects of resiting feeding tubes, two related studies were carried out. The first study, a trial, included respiratory monitoring of 29 infants on the third and/or seventh day after either the appliance and oroenteric tubes had been inserted, or, in the control group, after the nasoenteric tubes had been passed. After seven days, the infants using the palatal appliance had significantly less periodic breathing, central apnea, and movement than the control group. The second study showed that the removal of feeding tubes that had been in situ for several days reduced apnea rates and produced a significant increase in transcutaneous PO2.

Airway Obstruction↗
PubMed1983

Volume change in the growing canine mandible measured by intra-vital fluorescent dye three-dimensional reconstruction.

A reconstruction method was employed to study the relative contributions of bone deposition and resorption to the overall growth of an individual bone. Total bone volume and incremental bone volume were measured for 24 mandibles spanning an age range from 22 to 211 days. No obvious relationship was demonstrated between the overall rate of bone formation and age; however, the rate of bone formation per unit volume of the jaw conformed to an exponential curve. The rate of increase in bone volume fell to nearly zero over the experimental period, whilst the rate of new bone addition levelled out at 12-13 mm3/cm3 per day. Thus there was significant bone remodelling after adult size was reached.

Animals↗
PubMed1983

The management of class III and class III tendency occlusions using headgear to the mandibular dentition.

The use of extra-oral traction to the lower arch in the treatment of Class III malocclusion is described. The results of the treatment of 43 consecutive cases employing both removable and fixed appliances are analysed and compared with an untreated control group of 15 further cases. It was found that the Class III malocclusion in the study fell into three groups, the characteristic of each group giving an indication of the recommended treatment approach.

Adolescent↗
PubMedDate not supplied

Mitochondrial permeability transition in CNS trauma: cause or effect of neuronal cell death?

Experimental traumatic brain injury (TBI) and spinal cord injury (SCI) result in a rapid and significant necrosis of neuronal tissue at the site of injury. In the ensuing hours and days, secondary injury exacerbates the primary damage, resulting in significant neurologic dysfunction. It is believed that alterations in excitatory amino acids (EAA), increased reactive oxygen species (ROS), and the disruption of Ca(2+) homeostasis are major factors contributing to the ensuing neuropathology. Mitochondria serve as the powerhouse of the cell by maintaining ratios of ATP:ADP that thermodynamically favor the hydrolysis of ATP to ADP + P(i), yet a byproduct of this process is the generation of ROS. Proton-pumping by components of the electron transport system (ETS) generates a membrane potential (DeltaPsi) that can then be used to phosphorylate ADP or sequester Ca(2+) out of the cytosol into the mitochondrial matrix. This allows mitochondria to act as cellular Ca(2+) sinks and to be in phase with changes in cytosolic Ca(2+) levels. Under extreme loads of Ca(2+), however, opening of the mitochondrial permeability transition pore (mPTP) results in the extrusion of mitochondrial Ca(2+) and other high- and low-molecular weight components. This catastrophic event discharges DeltaPsi and uncouples the ETS from ATP production. Cyclosporin A (CsA), a potent immunosuppressive drug, inhibits mitochondrial permeability transition (mPT) by binding to matrix cyclophilin D and blocking its binding to the adenine nucleotide translocator. Peripherally administered CsA attenuates mitochondrial dysfunction and neuronal damage in an experimental rodent model of TBI, in a dose-dependent manner. The underlying mechanism of neuroprotection afforded by CsA is most likely via interaction with the mPTP because the immunosuppressant FK506, which has no effect on the mPT, was not neuroprotective. When CsA was administrated after experimental SCI at the same dosage and regimen used TBI paradigms, however, it had no beneficial neuroprotective effects. This review takes a comprehensive and critical look at the evidence supporting the role for mPT in central nervous system (CNS) trauma and highlights the differential responses of CNS mitochondria to mPT induction and the implications this has for therapeutically targeting the mPT in TBI and SCI.

Animals↗