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Biomedical subjects

N Marsh

Publications and source records attributed to N Marsh.

At least 19 recordsLinked to original sources
PubMed2001

Epsilon-aminocaproic acid promotes the release of alpha2-antiplasmin during and after cardiopulmonary bypass.

This double-blind, randomized study compared the mechanisms by which low-dose aprotinin and epsilon-aminocaproic acid (EACA) inhibited fibrinolysis during cardiopulmonary bypass surgery. D-dimer levels during and after bypass were similar, indicating an equivalent inhibition of fibrinolysis. Effects on tissue plasminogen activator release were not associated with the inhibition of fibrinolysis by either drug. Treatment with EACA was associated with a substantial release of endogenous alpha2-antiplasmin, particularly 1 h after bypass. Compared with the aprotinin group, higher levels of the plasmin-alpha2-antiplasmin complex in the EACA group confirmed an increased inhibition of plasmin by alpha2-antiplasmin. In conclusion, it is hypothesized that EACA inhibited fibrinolysis by stimulating the release of the patients' own alpha2-antiplasmin.

Aminocaproic Acid↗
PubMed2000

A short history of nitroglycerine and nitric oxide in pharmacology and physiology.

1. Nitroglycerine (NG) was discovered in 1847 by Ascanio Sobrero in Turin, following work with Theophile-Jules Pelouze. Sobrero first noted the 'violent headache' produced by minute quantities of NG on the tongue. 2. Constantin Hering, in 1849, tested NG in healthy volunteers, observing that headache was caused with 'such precision'. Hering pursued NG ('glonoine') as a homeopathic remedy for headache, believing that its use fell within the doctrine of 'like cures like'. 3. Alfred Nobel joined Pelouze in 1851 and recognized the potential of NG. He began manufacturing NG in Sweden, overcoming handling problems with his patent detonator. Nobel suffered acutely from angina and was later to refuse NG as a treatment. 4. During the mid-19th century, scientists in Britain took an interest in the newly discovered amyl nitrite, recognized as a powerful vasodilator. Lauder Brunton, the father of modern pharmacology, used the compound to relieve angina in 1867, noting the pharmacological resistance to repeated doses. 5. William Murrell first used NG for angina in 1876, although NG entered the British Pharmacopoeia as a remedy for hypertension. William Martindale, the pharmaceutical chemist, prepared '...a more stable and portable preparation': 1/100th of a grain in chocolate. 6. In the early 20th century, scientists worked on in vitro actions of nitrate-containing compounds although little progress was made towards understanding the cellular mode of action. 7. The NG industry flourished from 1900, exposing workers to high levels of organic nitrites; the phenomena of nitrate tolerance was recognized by the onset of 'Monday disease' and of nitrate-withdrawal/overcompensation by 'Sunday Heart Attacks'. 8. Ferid Murad discovered the release of nitric oxide (NO) from NG and its action on vascular smooth muscle (in 1977). Robert Furchgott and John Zawadski recognized the importance of the endothelium in acetylcholine-induced vasorelaxation (in 1980) and Louis Ignarro and Salvador Moncada identified endothelial-derived relaxing factor (EDRF) as NO (in 1987). 9. Glycerol trinitrate remains the treatment of choice for relieving angina; other organic esters and inorganic nitrates are also used, but the rapid action of NG and its established efficacy make it the mainstay of angina pectoris relief.

Europe↗
PubMed1999

Somatosensory evoked potentials in severe traumatic brain injury: a blinded study.

OBJECT: Beginning in 1979, the results of somatosensory evoked potential (SSEP) monitoring have been used to predict outcome in patients who have suffered severe brain trauma. The data indicate that if the cortical components of the SSEPs were bilaterally absent, the outcome was always death or a vegetative state, but previous studies have not been blinded. The aims of this study were to correlate the results of SSEP recordings with the outcome in a prospectively blinded manner and to assess whether monitoring of SSEPs was a useful adjunct to clinical judgment in the prediction of outcome. METHODS: The authors studied 105 severely head injured patients (median Glasgow Coma Scale score of 6) who were admitted to the Waikato Intensive Care Unit. The upper limb SSEPs were classified according to the central conduction time (CCT) as normal, of increased latency, or absent. The outcome as assessed using the Glasgow Outcome Scale (GOS) score was evaluated 12 months after the injury. CONCLUSIONS: Of 51 patients with a bilaterally normal CCT, 29 (57%) had a good outcome (GOS Score 5). Any delay in CCT was associated with a decreased incidence of good outcome (30%). Unilateral absence of the cortical component of the SSEP was usually associated with a poor outcome (death or severe disability), and bilateral absence was always associated with a poor outcome. The authors conclude that SSEPs correlate well with outcome and that this is not the result of investigator bias.

Adolescent↗
PubMed1997

The Gaboon viper, Bitis gabonica: hemorrhagic, metabolic, cardiovascular and clinical effects of the venom.

The effects of Bitis gabonica venom have been studied in several animal species, including the monkey, dog, rabbit, rat and guinea pig. Further information has been provided by observations on the effects of snake bite in man. Bitis gabonica venom exerts a number of cytotoxic and cardiovascular effects: cytotoxic effects include widespread hemorrhage, caused by the presence of two hemorrhagic proteins. These hemorrhagins bring about separation of vascular endothelial cells and extravasation of blood into the tissue spaces. Metabolic alterations include decreased oxygen utilization by tissues and increased plasma glucose and lactate concentrations. Metabolic non-compensated acidosis has also been seen in the rat as a consequence of the cytotoxicity of the venom. Cardiovascular effects include disturbances in atrio-ventricular conduction and reduction in amplitude and duration of the action potential brought about by a decreased calcium membrane conductance. A progressive decrease in myocardial contractility can also be attributed to the decreased calcium conductance, which together with the severe acidosis may cause death in experimental animals. A severe, though reversible, vasodilatation was observed after envenomation due to unidentified compounds in the venom. In man, envenomation causes a variable clinical picture depending on the time course and severity of envenomation. Frequently seen effects include hypotension, hemorrhage at the site of the bite and elsewhere and disseminated intravascular coagulation. Envenomation can be satisfactorily treated with antivenom.

Animals↗
PubMed1995

Relative contributions of voluntary apnoea, exposure to cold and face immersion in water to diving bradycardia in humans.

1. Diving or face immersion bradycardia is a well recognized but incompletely understood reflux which occurs in man and other mammals. 2. In order to investigate the contributions made by voluntary apnoea, face immersion in water and cold exposure, 18 normal subjects were exposed to these challenges separately and in various combination. 3. Tested individually, cold and apnoea caused significant reductions in heart beat (P < 0.01 and 0.002, respectively). Face immersion in thermoneutral water had no effect on heart rate. 4. The bradycardic effect of apnoea at maximal inspiration may be due to stimulation of pulmonary stretch receptors. 5. Cold exposure and voluntary apnoea applied simultaneously caused a summative effect but when tested with face immersion in water there was a synergistic response greater than the sum of individual responses. 6. The results confirm the bradycardic effect of apnoea and cold exposure, whereas immersion in thermoneutral water had little effect, a finding which has been disputed in the literature.

Adult↗
PubMed1995

Childhood onset of spinal cord injury: self-esteem and self-perception.

The effects of spinal cord injury in childhood upon later psychological adjustment were investigated by comparing a group of 86 people injured as children with a control group (matched for time since injury and level of injury) of people injured as adults. It was hypothesized that adolescence is a crucial period in psychological development and that the effect of spinal cord injury on body image, self-concept and social relationships during adolescence will have a long-term negative effect on psychological well-being. However, on overall measures of depression, self-esteem and self-perception, there were no significant differences between the experimental and control groups. Furthermore, there were no significant differences between paraplegics and tetraplegics, between men women, or between those who were involved in a significant intimate relationship and those who were not. These findings support previous research which has suggested that organic variables, such as age at injury and level of injury, are not predictive of long-term psychological adjustment.

Adaptation, Psychological↗
PubMed1991

Thrombin-like activity in snake venoms from Peruvian Bothrops and Lachesis genera.

Venoms from Lachesis muta muta, Bothrops pictus, B. barnetti, B. atrox and B. hyoprorus coagulate in vitro canine fibrinogen, and both bovine fibrinogen and bovine plasma. B. barnetti and L. muta muta venoms have greater activity on canine fibrinogen and B. atrox and B. hyoprorus venoms, a greater activity on bovine fibrinogen. Gel filtration showed one peak of coagulant activity in all venoms except B. atrox venom which possessed two peaks. The apparent mol. wt of these enzymes ranged from 45,000 to 69,000.

Animals↗
PubMed1991

Toxic substances in the environment affecting respiratory function of people in Hawaii.

In this trilogy we have collected data from authors who are concerned with patients with respiratory complaints. Surprisingly there are unique problems in the residents of our State. The full impact of problems known to cause respiratory illnesses, such as asbestosis, will not be known for years to come. Other problems such as the effect of sugarcane burning are just now being identified and may show a parallel to the inhalation of asbestos dust. VOG may be simply an irritant or it may explain in part the high incidence of asthma in our State. Clearly more work needs to be done to explain the pathophysiology, the risk and possible treatment for the consequences on people of these putative toxic substances.

Air Pollutants↗
PubMed1989

The reduction of bruxism using contingent EMG audible biofeedback: a case study.

This report describes the use of EMG biofeedback to reduce bruxism in an 18-year-old woman. The behaviour was severe and not responsive to standard dental treatment. In addition to psychometric measures of affective status, objective measures of both the frequency and intensity of bruxing incidents were made, and a 4-week intervention conducted. On the bruxing and affective measures significant improvements were noted, as were reductions in associated pain and dysfunction.

Acoustic Stimulation↗
PubMed1988

Crystallization and preliminary diffraction data for adenosylcobalamin-dependent methylmalonyl-CoA mutase from Propionibacterium shermanii.

Pink crystals of methylmalonyl-CoA mutase from Propionibacterium shermanii, a coenzyme B12 (5'-deoxyadenosylcobalamin)-dependent enzyme, have been obtained by the hanging-drop method in two different forms. One form lies in the space group P21, with unit cell dimensions a = 122 A, b = 160 A and c = 90 A, with beta = 104 degrees (1 A = 0.1 nm). There are two alpha beta dimers in the asymmetric unit. The crystals diffract to 3.2 A resolution and are suitable for high resolution X-ray diffraction studies.

Crystallization↗
PubMed1980

Some observations on the release of extrinsic and intrinsic plasminogen activators during exercise in man.

Exercise was found to cause the release of 'extrinsic' plasminogen activators into the bloodstream. The 'intrinsic' plasma plasminogen activators were not significantly altered although factor VIII clotting activity and, to a lesser extent, its related antigen were both raised. A small amount of systemic fibrin(-ogen)olysis was indicated by the generation of fragment X and a slight reduction in the amount of intact A alpha-fibrinogen chain present. Plasminogen and antiplasmins were not significantly affected by exercise. We conclude that exercise-induced fibrinolysis is brought about solely by the release of plasminogen activators(s) from the vessel wall but that this enhanced level of fibrinolysis is insufficient to produce a marked degree of systemic fibrin(ogen) breakdown.

Adult↗