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Biomedical subjects

J Mair

Publications and source records attributed to J Mair.

121 records · Page 7Linked to original sources
PubMed1991

Foetal life and a legal duty of care.

Until 1932 in England the right to sue for injuries caused by the fault of another was not recognised in the absence of contract. The law of negligence has expanded and developed as new facts are presented to the courts of their decision. One of the basic elements of the tort of negligence is proof that the defendant owed a duty of care to the plaintiff. The law with respect to those who suffer injury who are in being has been clearly defined. However, the law has now developed to hold that a child is born with injuries caused by the negligence of another whilst the child was in utero has a right to bring an action for compensation for those injuries provided the child is born alive. A further development in this area of law has been the legal recognition of a claim by a child who suffers injuries in utero caused by a negligent act committed against the mother at a time when the child was not even conceived provided the child can prove a duty of care was owed and that the injuries complained of were caused by the alleged negligent act. Thus midwives and other health professional who care for and advise pregnant women need to keep in mind that a duty of care may be owed to an unborn child or a future unborn child as well as to the pregnant women.

Abnormalities, Drug-Induced↗
PubMed1991

Release of cyclic guanosine monophosphate evaluated as a diagnostic tool in cardiac diseases.

Concentrations of atrial natriuretic peptide (ANP) are increased in plasma of patients with impaired cardiac and renal function. The second messenger of ANP, cyclic guanosine monophosphate (cGMP), is released into the plasma specifically upon stimulation of cells with ANP. Although nitrates can also activate intracellular cGMP synthesis, we detected no increase in plasma cGMP concentrations after infusions of glycerol trinitrate. Because immunoreactive ANP is highly susceptible to degradation and nonspecific influences in blood samples, determinations of ANP require immediate centrifugation and storage of plasma at -20 degrees C. In contrast, we found that cGMP is stable for five days in vitro in blood samples containing EDTA. In 147 healthy blood donors, the upper cutoff value for plasma cGMP was 6.60 nmol/L, not significantly different (P greater than 0.05) from that for 222 patients with disorders other than cardiovascular and renal. In 69 patients with manifest congestive heart failure (NYHA stages II-IV), 65 had increased cGMP values. Using the above cutoff value for cGMP gave diagnostic sensitivity of 94.2% and specificity of 93.7%. Plasma cGMP may thus provide an alternative for routine clinical measurements of ANP in cardiac diseases in the absence of renal disorders.

Adolescent↗
PubMed1991

Cardiac troponin T in diagnosis of acute myocardial infarction.

Troponin T is a structurally bound protein found in striated muscle cells. We tested concentrations of its cardiac-specific isotype in peripheral venous blood samples serially drawn from 72 patients with confirmed myocardial infarction. Fifty-nine patients received thrombolytic treatment with intravenous streptokinase, urokinase, or recombinant tissue-type plasminogen activator; because of contraindications, the remaining 13 patients did not. Concentrations of troponin T in plasma, measured by an enzyme-linked immunosorbent assay, started increasing within a few hours after the onset of symptoms (median, 4 h; range, 1-10 h). The sensitivity of troponin T for detecting myocardial infarction was 100% from 10 to 120 h after the onset of symptoms; sensitivity on the seventh day after admission was 84%. Concentrations were increased for up to three weeks in some patients with late or high peak values. Successful reperfusion in Q-wave infarction obviously influences the release of troponin T into plasma, with all such cases showing peak values less than or equal to 26 h (median, 14 h) after the onset of symptoms. Troponin T concentrations in these patients returned to within the reference interval more rapidly than in nonreperfused subjects. In the 13 patients without fibrinolytic therapy, troponin T tended to peak approximately 48 h (median) after the onset of chest pain. Troponin T concentrations in patients for whom thrombolysis was unsuccessful resembled those in patients without fibrinolytic therapy. The specificity of the assay was 96% as tested in samples of 96 emergency-room patients. The reference interval (less than 0.5 micrograms/L) was established from samples of 100 healthy blood donors. Troponin T measurements are a specific and sensitive method for the early and late diagnosis of acute myocardial infarction and could, therefore, provide a new criterion in laboratory diagnosis of its occurrence.

Adult↗
PubMed1990

Pharmacological activities of delta-aminolaevulinic acid, protoporphyrin IX and haemin in isolated preparations of rabbit gastric fundus and jejunum.

1. Pharmacological effects of delta-aminolaevulinic acid (ALA), protoporphyrin IX and haemin were examined in isolated preparations of rabbit jejunum and gastric fundus suspended in oxygenated Ringer-Locke solution at pH 7.0. 2. In jejunal preparations, delta-aminolaevulinic acid (3.0-4.5 mM), protoporphyrin IX (1.1-2.2 mM) and haemin (3.0-4.5 mM) dose-dependently reduced the amplitude of contractions and increased resting length. Pretreatment with prazosin (10(-7) M) inhibited effects produced by delta-aminolaevulinic acid (3 mM) and protoporphyrin IX (1.1 mM) but not those of haemin (3 mM). 3. In fundic preparations, dose-dependent contracture occurred in response to delta-aminolaevulinic acid (0.1-3.0 mM) protoporphyrin IX (0.1-2.2 mM) and haemin (0.6-6.3 mM). Effects qualitatively resembled those of noradrenaline (0.1-0.4 microM). Prazosin (10(-7) M) attenuated these effects, depressing the maximum response and causing a rightward shift of the concentration-response curves. 4. It is concluded that actions of delta-aminolaevulinic acid at alpha 1-adrenoceptor sites are unlikely to be related to the autonomic neuropathy of acute porphyria. Its in vitro effects occurred only at comparatively high concentrations and were mimicked by protoporphyrin IX and haemin. It is suggested that ALA is more likely to modify autonomic functions by an indirect action, since it is known at low dose levels to influence GABA-ergic functioning.

Aminolevulinic Acid↗
PubMedDate not supplied

Glycogen phosphorylase isoenzyme BB in diagnosis of myocardial ischaemic injury and infarction.

This review deals with glycogen phosphorylase (GP) and its isoenzyme BB in the diagnosis of ischaemic myocardial injury. Early identification and confirmation of acute myocardial infarction is essential for correct patient care and disposition decision in the emergency department. In this respect, glycogen phosphorylase isoenzyme BB (GPBB) based on its metabolic function is an enzyme for early laboratory detection of ischaemia. In the aerobic heart muscle GPBB together with glycogen is tightly associated with the vesicles of the sarcoplasmic reticulum. Release of GPBB, the main isoform in the human myocardium, essentially depends on the degradation of glycogen, which is catalyzed by GP. Ischaemia is known to favour the conversion of bound GP in the b form into GP a, thereby accelerating glycogen breakdown, which is the ultimate prerequisite for getting GP into a soluble form being able to move freely in the cytosol. The efflux of GPBB into the extracellular fluid follows if ischaemia-induced structural alterations in the cell membrane become manifest. The clinical application of GPBB as a marker of ischaemic myocardial injury is a very promising tool for extending our knowledge of the severity of myocardial ischaemic events in the various coronary syndromes. The rational roots of this development were originated from Albert Wollenberger's research work on the biochemistry of cardiac ischaemia and the transient acceleration of glycogenolysis mainly brought about by GP activation.

Anaerobiosis↗
PubMedDate not supplied

Tissue release of cardiac markers: from physiology to clinical applications.

The early release of cardiac markers is influenced by a variety of factors, the most important influence being their intracellular compartmentation. In contrast to the release of cytosolic proteins, the release of structurally bound proteins requires both a leaky plasma membrane and a dissociation or degradation of the subcellular structure, which is a slower process. Another major impact is the susceptibility to the degradation by cytosolic proteases, such as the calpains. The lysosomes are stable within the first 3-4 hours after onset of ischemia, and, therefore, their enzymes are not involved in the early degradation of structurally bound proteins. Troponin I and troponin T are substrates of micro-calpain. Current experimental as well as clinical results suggest that the molecular mass seems to be of minor importance for the pattern of appearance of myocardial proteins in blood after myocardial infarction. However, within the family of molecules with a certain intracellular compartmentation, the molecular mass is an influence on the appearance in blood, because heavier molecules diffuse at a slower rate, and particularly smaller molecules, such as myoglobin, may enter the vascular system to an even larger extent directly via the microvascular endothelium. The higher the concentration gradient of a marker between the cardiomyocytes and the interstitial space, the faster a parameter will translocate from sarcoplasma to the interstitial space as soon as the plasma membrane permeability is increased. Another influence is local blood and lymphatic flow. Recent experimental studies showed that reperfusion causes a true acceleration of cellular protein leakage by an acute manifestation of plasmalemmal disruptions and not just an enhanced wash out. Marker protein time-courses after myocardial damage are also markedly influenced by their disappearance rate from blood. Most proteins appear to be catabolized in organs with a high metabolic rate, such as liver, pancreas, kidneys, and the reticuloendothelial system. Smaller molecules, such as myoglobin, also pass the glomerular membranes of the kidneys and are reabsorbed and subsequently metabolized in tubular epithelial cells.

Biomarkers↗