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Biomedical subjects

L Karalliedde

Publications and source records attributed to L Karalliedde.

At least 19 recordsLinked to original sources
PubMed2004

Organophosphate toxicity and occupational exposure.

The ubiquitous organophosphates present a continuing health hazard in agriculture, public health eradication programmes and as chemical warfare agents. Despite significant progress in understanding the potential mechanisms of toxicity far beyond the commonly accepted mechanism of cholinesterase inhibition in intentional exposures, the precise health effects following occupational exposures are yet to be completely defined. A much greater understanding exists of the clinical features of organophosphate poisoning. These are characterized by a triphasic response involving an initial acute cholinergic phase, an intermediate syndrome (both associated with high mortality) and a disabling but non-lethal delayed polyneuropathy. The delayed polyneuropathy may occur in the absence of the cholinergic or intermediate phases. However, progress is still required in order to improve the quantification and assessment of occupational exposures and the implementation of appropriate preventive measures. Finally, evidence-based guidelines for appropriate or optimal therapeutic interventions following poisoning are required urgently and collaborative work with colleagues in developing countries, where the occurrence of organophosphate exposures is more frequent, may provide the answers.

Cholinesterases↗
PubMed2000

Possible immediate and long-term health effects following exposure to chemical warfare agents.

Agents of chemical warfare continue to pose a threat to human life. Organophosphorus compounds are possibly the best known and most used agents in recent times. These are known to produce acute ill health and death and, probably equally important, many diverse delayed effects, many of which are not clinically nor pathologically well defined. The immediate and delayed effects of organophosphorus compounds, in particular, and those of other known agents of chemical warfare, such as mustard gas, Lewisite, phosgene, cyanides and the newer crowd control agents, are reviewed. Environmental sequelae of these agents are gaining importance as probable causes of chronic ill health amongst those living in regions where these agents have been used. The need to study the pattern of disease in exposed populations is emphasised.

Animals↗
PubMed1999

Organophosphorus poisoning and anaesthesia.

Organophosphorus compounds, used as insecticides and agents of chemical warfare, are a major global cause of health problems. These irreversible inhibitors of cholinesterase produce three well-recognised clinical entities: the initial cholinergic phase, which is a medical emergency often requiring management in an intensive care unit; the intermediate syndrome, during which prolonged ventilatory care is necessary; and delayed polyneuropathy. In addition, disturbances of body temperature and endocrine function, electrolyte imbalances, immunological dysfunction and disorders of reproduction have been reported in animals and man. Vocal cord paralysis, pancreatitis, cardiac arrhythmias and a wide range of neuropsychiatric disorders are known to follow acute and chronic exposure to organophosphorus compounds. As a result of the inhibition of plasma cholinesterase, there can be increased sensitivity to drugs hydrolysed by this enzyme, e.g. suxamethonium and mivacurium. The inhibition of acetylcholinesterase causes dysfunction at the neuromuscular junction which can produce altered responses to nondepolarizing neuromuscular blockers. Anaesthetists may encounter patients exposed to organophosphorus compounds either following acute poisoning, trauma (warfare) or as patients with a wide range of nonspecific disorders presenting for surgery. The traditional use of oximes and atropine in treatment has failed to reduce the morbidity and mortality associated with poisoning. The roles of agents that have reduced the toxicity of organophosphorus compounds in animal experiments are discussed as potential therapeutic agents. There is an urgent need for accurate information on the problems associated with exposure to organophosphorus compounds. This would best be achieved by collaborative research between technologically advanced countries and developing countries, where organophosphorus compounds are a leading cause of ill health.

Anesthesia↗
PubMed1998

Drug interactions and the clinical anaesthetist.

In clinical practice, anaesthetists encounter many patients who are on concurrent medication which may have the potential to interact with drugs used during anaesthesia. Many patients are receiving as many as a dozen drugs of various kinds, thus, increasing the risk of a drug interaction occurring. Unfortunately anaesthetists tend not to report drug interactions which occur during anaesthesia--especially those of a minor nature such as flushing--and hence, the true number of drug interactions is unknown. We have developed a chart indicating the nature of important interactions that the anaesthetist may encounter.

Anesthesia↗
PubMed1996

Drug interactions with neuromuscular blockers.

Drugs administered to patients undergoing anaesthesia may complicate the use of the neuromuscular blockers that are given to provide good surgical conditions. The various sites of interaction include actions on motor nerve conduction and spinal reflexes, acetylcholine (ACh) synthesis, mobilisation and release, sensitivity of the motor end plate to ACh and the ease of propagation of the motor action potential. In addition, many drugs affect the pharmacokinetics of neuromuscular blockers, especially as most drugs depend to a greater or lesser extent upon renal excretion. The clinically significant interaction between nondepolarisers and depolarisers may be due to blockade of the pre-synaptic nicotinic receptors by the depolarisers, leading to decreased ACh mobilisation and release. Synergism between nondepolarisers probably results from post-synaptic receptor mechanisms. Volatile anaesthetic agents affect the sensitivity of the motor end-plate (post-synaptic receptor blockade) in addition to having effects on pre-synaptic nicotinic function. The effects of nondepolarisers are likely to be potentiated and their action prolonged by large doses of local anaesthetics due to depression of nerve conduction, depression of ACh formation, mobilisation and release, decreases in post-synaptic receptor channel opening times and reductions in muscular contraction. Most antibacterials have effects on pre-synaptic mechanisms. Procainamide and quinidine principally block nicotinic receptor channels. Magnesium has a marked inhibitory effect on ACh release. Calcium antagonists could theoretically interfere with neurotransmitter release and muscle contractility. Phenytoin and lithium decrease ACh release, whilst corticosteroids and furosemide (frusemide) tend to increase the release of the transmitter. Ecothiopate, tacrine, organophosphates, propanidid, metoclopramide and bambuterol depress cholinesterase activity and prolong the duration of the neuromuscular block. The probability of clinically significant interactions increases in patients receiving several drugs with possible effects on neuromuscular transmission and muscle contraction.

Adrenal Cortex Hormones↗
PubMed1995

Animal toxins.

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Amphibian Venoms↗
PubMed1995

Unfinished business: adult immunization against tetanus.

Where effective child immunization schemes have been established virtually all cases of tetanus occur in persons aged over 50 years. Adult immunization programmes should be introduced in order to protect this age group against the disease.

Age Factors↗
PubMed1993

Immunity to tetanus in United Kingdom populations.

As tetanus, a totally preventable disease, is still encountered in the older age group in England and Wales, a study was carried out to assess the state of immunity to the disease in the elderly population. These levels were compared to those in recruits and service personnel in the Army. Elderly patients with underlying disease had lower levels than the elderly who were healthy. When compared with recruit population the elderly group had significantly lower levels of antibody. If tetanus is to be eliminated, an effective programme of immunisation extending throughout life must be ensured.

Adolescent↗
PubMed1993

A scale to assess severity in organophosphorus intoxication: POP scale.

We have developed a clinical scale to assess severity or organophosphorus (OP) intoxication. Five common clinical manifestations of OP poisoning have been selected as parameters, each to be assessed on a 3 point scale varying from 0-2. Poisoning can then be graded as mild (score 0-3), moderate (score 4-7) or severe (score 8-11) when the patient first presents. The scale was validated using two consecutive series of 173 patients with OP poisoning. Correlations between the scores obtained on admission and three outcome variables, namely, death, the need for ventilatory support and the dose of atropine required in the first 24 hours after admission were significant. We believe that this scale would assist in grading severity of OP intoxication at first contact and help in predicting possible outcome.

Bradycardia↗
PubMed1991

Chemical weapons.

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Anesthetics↗