Biomedical subjects
A E Richardson
Publications and source records attributed to A E Richardson.
The role of a (Ca2+ + Mg2+)-ATPase of the rough endoplasmic reticulum in regulating intracellular Ca2+ during cholinergic stimulation of rat pancreatic acini.
Rough endoplasmic reticulum membranes, purified from isolated rat pancreatic acini stimulated by carbachol, had a decreased Ca2+ content and increased (Ca2+ + Mg2+)-ATPase activity. Ca2+ was regained and ATPase activity reduced to control levels only after blockade by atropine. The (Ca2+ + Mg2+)-ATPase was activated by free Ca2+ (half-maximal at 0.17 microM; maximal at 0.7 microM) over the concentration range which occurs in the cell cytoplasm. Pretreatment with EGTA, at a high concentration (5 mM), inhibited ATPase activity which, our results suggest, was due to removal of a bound activator such as calmodulin. The rate of (Ca2+ + Mg2+)-ATPase actively declined during the 10-min period over which maximal active accumulation of Ca2+ by membrane vesicles occurs. In the presence of ionophore A23187, which released actively accumulated Ca2+ and stimulated the (Ca2+ + Mg2+)-ATPase, this time-dependent decline in activity was not observed. Our data provide evidence that the activity of the Ca2+-transporting ATPase of the rough endoplasmic reticulum is regulated by both extra and intravesicular Ca2+ and is consistent with a direct role of this enzyme in the release and uptake of Ca2+ during cholinergic stimulation of pancreatic acinar cells.
Solid haemangioblastomas of the posterior fossa: radiological features and results of surgery.
Cerebellar haemangioblastomas are benign neoplasms which have been reported to have a favourable prognosis. The authors report the experience of Atkinson Morley's Hospital, London with 14 cases of solid haemangioblastoma since the introduction of the CT scan. Death or a poor result occurred in 50% of cases. Incomplete excision carried a high risk of complications. The CT scan appearances were too non specific to make an accurate preoperative diagnosis, the lesions usually being mistaken for meningiomas. Vertebral angiography can be of considerable help in identifying their vascular anatomy.
Ventricular dilatation and communicating hydrocephalus following spontaneous subarachnoid hemorrhage.
Ventricular dilatation following spontaneous subarachnoid hemorrhage (SAH) is a well recognized phenomenon. Its clinical significance, however, remains controversial. Two phases are distinguished, the acute or early, occurring soon after the ictus, and the chronic or late, developing after the second week. The authors studied the ventricular size in 210 patients with spontaneous SAH through the course of their illness and convalescence by means of serial computerized tomography (CT) scans. Their findings suggest that ventricular dilatation soon after SAH is not always clinically significant and does not necessarily require shunting before definitive surgery. Delayed symptomatic ventricular enlargement (communicating hydrocephalus) occurs in 7% of the patients and can be safely diagnosed on the basis of the clinical picture and CT scan appearances. Treatment with a ventricular shunting system is almost invariably rewarding.
Acoustic neurinoma in a child.
A very large acoustic neurinoma in a ten-year-old girl is reported. The diagnosis was based on the clinical findings and the CT scan. The pertinent literature is reviewed.
The long-term prognosis in untreated cerebral aneurysms: II. Late morbidity and mortality.
Three hundred sixty-four patients who suffered a subarachnoid hemorrhage from an aneurysm at either the anterior (ACA) or posterior (PCA) communicating artery location and who were not surgically treated have been followed for up to 21 years in order to study the late morbidity and mortality. For patients surviving six months: (1) little improvement in morbidity was noted during the many years of subsequent follow-up; (2) in general, ACA patients fared better than PCA patients; (3) the neurological state on original admission was strongly correlated with the degree of morbidity; (4) other factors measured at time of original hemorrhage which adversely affected morbidity included the level of blood pressure or the presence of clot or spasm; (5) if deaths from late hemorrhage are excluded, cardiovascular causes account for the majority of subsequent deaths; and (6) the risk of dying from all causes is increased when compared to a population matched by age and sex.
Multiple intracranial aneurysms: identifying the ruptured lesion.
The problems associated with the identification of the source of bleeding in multiple intracranial aneurysms are discussed, and the contribution towards diagnosis of each method of examination and investigation are evaluated, special emphasis is laid on the use of CAT scanning and electroencephalography as additional aids in localisation.
Effect of piracetam on level of consciousness after neurosurgery.
2-oxopyrollidine acetamide (piracetam) is said to protect the cerebral cortex against hypoxia. Since surgery is believed to aggravate cerebral hypoxia and the consequent neurological dysfunction, patients undergoing surgery for brain tumours or ruptured cerebral aneurysms were studied. A random, non-stratified study of 100 patients showed that a significantly higher percentage of patients receiving piracetam attain or maintain a normal or near-normal level of consciousness postoperatively than those receiving a placebo. No side-effects or interaction of piracetam with other medications were noted.
The long-term prognosis in untreated cerebral aneurysms: I. The incidence of late hemorrhage in cerebral aneurysm: a 10-year evaluation of 364 patients.
Three hundred sixty-four patients who suffered a subarachnoid hemorrhage from an aneurysm in either the posterior communicating or anterior communicating artery and who were not surgically treated have been followed for up to 21 years in order to determine the frequency of subsequent hemorrhage. For patients surviving six months: (1) rebleeding occurs on the average of 3.5% per year during the first decade; (2) the mortality associated with a late rebleed is 67%; (3) high blood pressure and female sex predispose to late rebleeding in posterior communicating artery aneurysms; (4) young patients take longer to rebleed than older patients but do so at the same rate; and (5) increase in aneurysm size as judged by routine arteriography six months after the initial hemorrhage did not correlate with rebleeding, although an increase in size had occurred in all patients who were studied angiographically at the time of their late rebleed.
Computerized axial tomography in idiopathic hydrocephalus.
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The natural history of intracranial aneurysms: rebleeding rates during the acute and long term period and implication for surgical management.
1. In the first 6 months, at least 50% of the patients with untreated anterior and posterior communicating artery aneurysms will rebleed. 2. Thereafter, the rate of rebleeding is not less than 3%/year with two-thirds of these late hemorrhages resulting in a mortality. 3. Carotid ligation for posterior communicating aneurysms protects against a high rate of rebleeding for 6 months, but thereafter the rate is not different from the course of untreated aneurysms. 4. On the basis of these first three points and a review of the literature, a theory is proposed that incidental and symptomatic unruptured aneurysms, multiple unruptured aneurysms, and subarachnoid hemorrhage where no lesion is demonstrable, have a natural history similar to that of the untreated aneurysm that survives at 6 months. Namely, we would predict a yearly rebleed rate of not less than 3%/year.
Late morbidity and mortality of common carotid ligation for posterior communicating aneurysms. A comparison to conservative treatment.
The long-term evaluation of 60 patients who suffered a subarachnoid hemorrhage and survived 6 months is reported. By bilateral carotid arteriography, all patients were shown to have a single aneurysm at the vicinity of the posterior communicating artery at its junction with the internal carotid artery. The patients had previously been randomly assigned to treatment either by bed rest or by common carotid ligation. Average duration of survival among those followed is 8 years. Late rebleeding episodes were found to occur at a similar rate, irrespective of mode of treatment in the studied populations, but morbidity following operation continued to remain somewhat less over the ensuing years of follow-up study compared with the patients treated conservatively. On final assessment many years after the original hemorrhage, there is little improvement in degree of morbidity in either treatment group, and hypertension is noted to develop in the patients undergoing carotid ligation. A larger number of cases will be required to validate these findings.
Cerebral blood flow and cerebral blood volume in patients with sub-arachnoid haemorrhage.
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A quantitative study of the EMI values obtained for normal brain cerebral infarction and certain tumours.
A quantitative study has been made of the EMI numbers of normal brain, cerebral infarction and certain tumours. The scans were recorded on magnetic tape and analysed using a minicomuter linked to a graphic display unit. This system not only yielded 16 grey scales compared with the ten currently available, but was programmed to allow selected regions of the scans to be outlined. From these regions the computer calculated the area, the mean EMI number and its standard deviation. It was found that in 15 normal brain scans, the EMI values obtained for normal frontal and temporal lobes were similar, but that the values for the basal ganglia and occipital lobes were significantly different from the first two regions and from each other. Ten cases of cerebral infarction and 30 cases of cerebral tumour were analysed, and it was shown that analysing representative areas was more informative than surveying the whole lesion. Whilst only half of the scans of brain tumours had a significantly altered EMI number compared with that of normal brain, enhancement of tumour density with sodium iothalamate revealed a consistent and significant elevation of the EMI number for all tumours. In particular, the value for enhanced meningiomas was almost double and malignant tumours more than a third larger than normal brain. It was not possible to differentiate quantitatively between astrocytomas and metastases.
The Lancet - Saturday II October 1975. Sodium iothalamate as an aid to diagnosis of intracranial lesions by computerised transverse axial scanning.
The diagnostic accuracy of computerised transverse axial tomography in conjunction with enhancement of tissue density by sodium iothalamate was assessed in 438 patients, 256 of them having intracranial tumours and 182 having other intracranial disorders. THE 80 X 80 matrix and 20 ml intravenous sodium iothalamate were used in 174 patients, the 160 X 160 matrix and 20 ml sodium iothalamate in 126 patients, and the 160 X 160 matrix and 60 ml sodium iothalamate in 138 patients. The diagnostic accuracy rose from 87% in the first group to 100% in the final group. The proportion of patients showing enhancement of tumour tissue density improved from 64% in the first group to 96% in the third. In the non-tumour patients, excluding those in whom the underlying disease caused no alteration of brain structure or tissue density, the overall accuracy was 96%, being unaffected by the modifications of technique. The enhancement of tissue density in brain abscesses, some cerebral infarcts, and angiomas could be readily distinguished from that seen in tumours.
An assessment of the accuracy of computerized transverse axial scanning (EMI scanner) in the diagnosis of intracranial tumour. A review of 366 patients.
The computerized transverse axial (CTA) scans of 366 patients with intracranial tumours and 267 patients without tumours, but with similar presenting features, were analyzed. In all cases the definitive diagnosis was established either by histological or neurological methods. Most tumours were found to be of low tissue density, but a gradation from low through normal to a high density appearance was recognized. Tissue density enhancement with sodium iothalamate was achieved in 63-9% of supratentorial and 62-4% of infratentorial tumours, and usually allowed a more accurate determination to be made of the boundary between the tumour and the surrounding oedema. The accuracy of the CTA scanner as a screening technique was found to be 96%, this being superior to either clinical evaluation or rectilinear isotope scanning. When assessed on the basis of structural abnormalities demonstrated in the same groups of patients, the CTA scans enabled a diagnosis to be made or a lesion excluded in 92-3% of the patients, a figure which bears comparison with arteriography and pneumo-encephalography. It is anticipated that the simplicity and superior sensitivity of the system should decrease the necessity for invasive techniques such as angiography and pneumo-encephalography in the future.
Letter: E-aminocaproic acid and subarachnoid haemorrhage.
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