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Biomedical subjects

L Evans

Publications and source records attributed to L Evans.

At least 181 records · Page 10Linked to original sources
PubMed1980

Amniotic fluid acetylcholinesterase isoenzyme patterns in the diagnosis of neural tube defects.

Acetylcholinesterase isoenzyme patterns were determined in amniotic fluid from 140 normal pregnancies and from 68 pregnancies with various fetal abnormalities. A fast acetylcholinesterase isoenzyme was detected in all cases of neural tube defect, exomphalos and intrauterine death. The fast isoenzyme was not seen in any of the normal pregnancies. Blood-contaminated amniotic fluids with false positive elevation of alphafetoprotein gave a single isoenzyme band. The qualitative demonstration of a fast acetylcholinesterase isoenzyme in amniotic fluid provides a useful adjunct to the alphafetoprotein assay in the prenatal diagnosis of neural tube defects.

Acetylcholinesterase↗
PubMed1980

Psychological effects caused by drugs in overdose.

Drug overdose is a common occurrence which accounts for up to 25% of medical inpatient admissions. Intentional overdose or attempted suicide is the most common cause of overdose, but there are other types of overdose which are often unrecognised as are the effects caused by these overdoses. Iatrogenic overdose occurs frequently and is often unavoidable. Many patients will make mistakes with their treatment and unwittingly suffer from the toxic effects of the drugs they are taking. About 7% of intentional overdose patients who are admitted to hospital have taken the drug for some psychological effect they have been seeking and have taken too much. This group is described as those who take 'drugs for kicks'. As many of the drugs taken cross the blood-brain barrier and exert some toxic effect on the cerebral cortex, secondary psychological disturbances frequently occur in all of these groups of patients, and can sometimes be the only sign of dangerous toxicity. It is important to recognise the patient's gross disturbances of behaviour, thinking and perception as a manifestation of drug toxicity which can be life threatening and often requires intense medical treatment. The range of the psychological response is somewhat limited and there is not a specific psychological disturbance characteristic of the toxicity of each group of drugs. However, there are some reactions which, coupled with the physical symptoms shown by the patient, can help to identify the patient as suffering from the toxic effects of drugs and even give some indication as to the type of drugs taken. This article describes the various psychiatric syndromes caused by drugs in overdose and attempts to identify these with most of the commonly encountered groups of drugs.

Analgesics↗
PubMed1979

Synaptic vesicle exocytosis captured by quick freezing and correlated with quantal transmitter release.

We describe the design and operation of a machine that freezes biological tissues by contact with a cold metal block, which incorporates a timing circuit that stimulates frog neuromuscular junctions in the last few milliseconds before thay are frozen. We show freeze-fracture replicas of nerve terminals frozen during transmitter discharge, which display synpatic vesicles caught in the act of exocytosis. We use 4-aminopyridine (4-AP) to increase the number of transmitter quanta discharged with each nerve impulse, and show that the number of exocytotic vesicles caught by quick-freezing increases commensurately, indicating that one vesicle undergoes exocytosis for each quantum that is discharged. We perform statistical analyses on the spatial distribution of synaptic vesicle discharge sites along the "active zones" that mark the secretory regions of these nerves, and show that individual vesicles fuse with the plasma membrane independent of one another, as expected from physiological demonstrations that quanta are discharged independently. Thus, the utility of quick-freezing as a technique to capture biological processes as evanescent as synaptic transmission has been established. An appendix describes a new capacitance method to measure freezing rates, which shows that the "temporal resolution" of our quick-freezing technique is 2 ms or better.

Aminopyridines↗
PubMed1979

Assignment of the human acid alpha-glucosidase gene (alphaGLU) to chromosome 17 using somatic cell hybrids.

Hybrid clones (MOGs) were made between the mouse line RAG and a primary fibroblast line from an individual of the rare alphaGLU 2 phenotype. Fifteen independent primary clones and 32 subclones were tested for the presence of human alphaGLU after separation of the human and rodent enzymes by starch gel electrophoresis. Twenty-three other human-mouse hybrids from six different crosses were analysed for the presence of human alphaGLU by exploiting a difference in the thermostability of the human and mouse enzymes. The hybrids were also analysed for up to 25 other enzymes which were used as markers for different human chromosomes. Two of the MOG hybrids were karyotyped and karyotype data were already available for a number of the other hybrids. The combined results demonstrate that alphaGLU is located on chromosome 17, and probably on 17q.

Animals↗
PubMed1979

Sialidosis type 1: cherry red spot-myoclonus syndrome with sialidase deficiency and altered electrophoretic mobility of some enzymes known to be glycoproteins. II. Enzymes studies.

Observations have been made on two brothers who had progressive ataxia, intention myoclonus and visual failure starting early in the third decade of life. Their parents were consanguineous. The brothers showed bilateral cherry red spots at the maculae and bilateral perinuclear cataracts; their intelligence was preserved. Urine was found to contain large amounts of sialylated oligosaccharides; cultured skin fibroblasts showed deficiency of the enzyme sialidase (neuraminidase). Studies on leucocytes and cultured skin fibroblasts showed aberrant electrophoretic mobilities of six enzymes all of which are known to be glycoproteins, and this has been attributed to excessive amounts of sialic acid on the enzyme molecules. The clinical features together with the biochemical findings indicate that these are further cases of the newly described condition Sialidosis Type 1 and it is suggested that the electrophoretic findings might be typical of the condition.

Adult↗
PubMed1978

A case of lithium poisoning? A cautionary tale.

The case of a 58 year old woman on maintenance lithium therapy who developed an acute organic brain syndrome is reported. The patient subsequently showed evidence of persistent brain damage. It is suggested that lithium toxicity was precipitated by electrolyte disturbances possibly caused by self medication with a diuretic, where serum levels of lithium were an unreliable measure of impending toxicity.

Benzothiadiazines↗
PubMed1977

Focused psychiatric curriculum selection: student, psychiatrist, and nonpsychiatrist physician expectations.

The authors obtained curriculum needs analysis data from second-year medical students and compared these with data obtained from nonpsychiatrist physicians and psychiatrists. All groups felt that interviewing skills, the doctor-patient relationship, managing the dying patient, and evaluation of suicidal patients were important topics. All gave psychological testing, behavior modification, mental retardation, and psychoanalytic theory the lowest teaching priority. The students gave a higher rating to all topics than did the other groups. The authors suggest that this kind of analysis can facilitate curriculum selection and implementation.

Attitude of Health Personnel↗