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The entry of 125I-metrizamide and of 125I-diatrizoate from blood into brain has been studied in rabbits. The blood-brain barrier is very tight to both molecules, all cerebral regions having spaces between 0.5 and 2% after maintenance of constant blood levels for 4 h. In extraneural tissues both compounds appear to distribute in extracellular fluid except for accumulation of metrizamide by the liver and perhaps the small intestine. Profiles of radioactivity through cerebral gray matter have been obtained following ventriculocisternal perfusion of artificial cerebrospinal fluid containing 125I-metrizamide. The nature of these profiles and their behavior with time suggest that metrizamide passes through gray matter by simple diffusion, that it is largely distributed in the extracellular fluid and that back movement across the blood-brain barrier is small.

Angiotensin II (AII) binding sites were characterized in human myometrium membrane preparations. The sites were saturable and of high affinity (Kd of 0.09 nM and Bmax of about 200 fmol/mg of protein). PD 123319 completely inhibited 125I-AII binding, with an IC50 of 30 nM, whereas L-158,809 (1 microM) had no significant effect on 125I-AII binding. These results indicate that human myometrium contains almost exclusively the AT2 receptor subtype. Association and dissociation studies performed with 125I-AII on human myometrium membranes revealed that AII had a very high affinity for AT2 receptors, with a Kd of 0.01 nM (association rate constant K1 = 1.056 x 10(12) mol-1 min-1; dissociation rate constant K2 = 0.003 min-1). The photoactivable AII analogue [Sar1, Val5, D-Phe8(N3)]AII displayed a high affinity for AT2 receptors (IC50 of 0.18 nM), but its radioiodinated form showed poor efficiency in photoaffinity labeling experiments. A newly synthesized photoactivatable analogue of AII, [Sar1, p-benzoyl-Phe8]AII, (AII-Bpa), also displayed a high affinity for AT2 receptors of human myometrium (IC50 of 0.3 nM). Photoaffinity labeling experiments were performed with 125I-AII-Bpa, and a high yield (70%) of covalent incorporation to human myometrium membranes was obtained upon photolysis. Covalently labeled receptors were solubilized, denatured, and subjected to polyacrylamide gel electrophoresis. Autoradiography of the polyacrylamide gel revealed a single band, of 68 kDa, and the labeling of this band was completely abolished in the presence of 1 microM PD 123319, indicating selective labeling of the AT2 receptor subtype. These results demonstrate that AII-Bpa is a very efficient tool for selective photoaffinity labeling of the AT2 receptor.

In a wide variety of cells, inositol-1,4,5-triphosphate is a second messenger that interacts with specific intracellular receptors and triggers the release of sequestered Ca2+ from an intracellular store. We have looked at the influence of heparin on the action and metabolism of inositol-1,4,5-triphosphate in the bovine adrenal cortex. Heparin blocked inositol-1,4,5-trisphosphate binding with half-maximal efficiency around 10 micrograms/ml. Scatchard analyses revealed that heparin did not change the affinity but decreased the number of available binding sites. The Ca2+-releasing activity of inositol-1,4,5-trisphosphate was monitored with the fluorescent indicator, fura-2. Heparin blocked this activity with half-maximal effeciency around 10 micrograms/ml. The effect of heparin could be overcome by a supramaximal dose of inositol-1,4,5-trisphosphate (25 microM). The activity of inositol-1,4,5-trisphosphate-3-kinase from bovine adrenal cortex cytosol was also studied. Heparin inhibited the activity of the kinase with a half-maximal effeciency around 0.4 microgram/ml. Lineweaver-Burk plots revealed that this potent effect was noncompetitive. Finally, we observed that heparin is without effect on inositol-1,4,5-trisphosphate-5-phosphatase (at concentrations as high as 2 mg/ml). These results are consistent with the suggestion that the binding sites for inositol-1,4,5-trisphosphate are the intracellular receptors responsible for the Ca2+-mobilizing effects of inositol-1,4,5-trisphosphate. These results also show that the kinase, the phosphatase, and the receptor are three different molecular entities, which are affected in a different manner by heparin.

Hormonal stimulation of Gq-protein coupled receptors triggers Ca2+ mobilization from internal stores. This is followed by a Ca2+ entry through the plasma membrane. Drosophila Trp and Trpl proteins have been implicated in Ca2+ entry and three mammalian homologues of Drosophila Trp/Trpl, hTrp1, hTrp3 and bTrp4 (also bCCE) have been cloned and expressed. Using mouse brain RNA as template, we report here the polymerase chain reaction-based cloning and functional expression of a novel Trp, mTrp6. The cDNA encodes a protein of 930 amino acids, the sequence of which is 36.8, 36.3, 43.1, 38.6, and 74. 1% identical to Drosophila Trp and Trpl, bovine Trp4, and human Trp1 and Trp3, respectively. Transient expression of mTrp6 in COS.M6 cells by transfection of the full-length mTrp6 cDNA increases Ca2+ entry induced by stimulation of co-transfected M5 muscarinic acetylcholine receptor with carbachol (CCh), as seen by dual wavelength fura 2 fluorescence ratio measurements. The mTrp6-mediated increase in Ca2+ entry activity was blocked by SKF-96365 and La3+. Ca2+ entry activity induced by thapsigargin was similar in COS cells transfected with or without the mTrp6 cDNA. The thapsigargin-stimulated Ca2+ entry could not be further stimulated by CCh in control cells but was markedly increased in mTrp6-transfected cells. Records of whole cell transmembrane currents developed in response to voltage ramps from -80 to +40 mV in control HEK cells and HEK cells stably expressing mTrp6 revealed the presence of a muscarinic receptor responsive non-selective cation conductance in Trp6 cells that was absent in control cells. Our data support the hypothesis that mTrp6 encodes an ion channel subunit that mediates Ca2+ entry stimulated by a G-protein coupled receptor, but not Ca2+ entry stimulated by intracellular Ca2+ store depletion.

Eighty colour subtractions of cerebral angiograms have been analysed to assess their value in actual diagnosis, particularly of cerebrovascular disease. The method has been found to be so valuable, either for confirmation of the findings seen on the original angiograms or in providing new data about the accurate localization and nature of the lesion, that it has now become a routine for all cerebrovascular cases. A selection of cases is presented and the limitations of the method discussed.

Angiography under experimental conditions shows that Urografin has a vasodilator action of the order of 8% upon the basal cerebral arteries of the baboon. This action is not seen within the first 4 sec of the angiogram and the dilator effect of a single injection has passed off completely 15 min later. Three successive injections within 7 min show little evidence of cumulative vasodilatation. The vasodilator action of three successive angiograms has disappeared 22 to 29 min later. Because of wide variations in the degree of vasodilatation shown by individual baboons it may be necessary to use each baboon as its own control in subsequent work.

Endocrinologists tend to accept minor variations of the pituitary fossa as evidence of the presence of a pituitary gland abnormality. Neuroradiologists tend to be sceptical. Normal criteria have not been established. In a consecutive series of 85 cases without any clinical evidence of a pituitary lesion, the plain films in 31·7 per cent demonstrated minor duplication of the floor or anterior wall of the pituitary fossa (with or without associated thinning and possible erosion of the lamina dura), which could be mistaken for the early signs of pituitary enlargement by an intrasellar tumour. 16·5 per cent showed thinning of the lamina dura on tomography, a feature previously taken as suggesting early enlargement. It is suggested that these particular diagnostic signs should be interpreted with caution.

This paper describes the initial findings of computerassisted diagnosis of cerebral tumours using Bayes' Theorem and CT scans. For various sets of signs, tables of accuracy and reliability have been constructed, and a computer versus radiologist analysis for three types of tumour has been made. Based only on the results of CT scans, the computer has produced diagnoses relatively quickly, and overall these are of reasonable accuracy when compared with the radiologists' reports. The worst results occurred in the prediction of meningiomas, the reasons for which will be examined in subsequent work.

Angiotensin II (AII) is an important regulator of aldosterone secretion by adrenal glomerulosa cells. All interacts with a specific receptor coupled to a guanine nucleotide-binding protein that controls the activity of phospholipase C. Recently, novel All nonpeptide antagonists (DuP-753 and PD-123319) have been shown to discriminate between two subclasses of All receptors in many different tissues. Our studies confirmed that 125I-All specifically labeled two classes of binding sites for All in a membrane preparation of bovine adrenal glomerulosa cells. The first class (DuP-753 sensitive) represented approximately 85% of the total binding sites for All and possessed a high affinity (IC50 of 92.9 +/- 19.5 nM) for DuP-753. PD-123319 did not have any effect on 125I-All binding to this site. The second class of binding sites was more sensitive to PD-123319, with an IC50 of 6.9 +/- 3.7 nM, and had a much lower affinity for DuP-753 (IC50 around 10 microM). The two classes of receptors had different affinities for All. All showed an affinity around 2 nM for All type 1 receptor (AT1)(DuP-753 sensitive) and a higher affinity, around 0.3 nM, for All type 2 receptor (AT2) (PD-123319 sensitive). All-induced steroidogenesis was completely abolished in the presence of 3 microM DuP-753, indicating that this activity was mediated through a DuP-753-sensitive receptor. We also found that polyvinyl sulfate (PVS), a polyanion, could partly inhibit the binding of 125I-All to bovine adrenal glomerulosa cell membranes, with half-maximal efficiency at 17.3 +/- 8.2 nM. The inhibitory effect of PVS was selective for AT1. The inhibitory effect of PVS was due to a change in the affinity state of the receptor. Unexpectedly, PVS had no effect on All-induced steroidogenesis or on All binding to intact bovine adrenal glomerulosa cells. However, the inhibitory effect of PVS on All binding was recovered after permeabilization of cells. Direct interaction of polyanions with AT1 was suggested by the capacity of solubilized photoaffinity-labeled 125I-AT1 to adsorb to heparin-agarose gels. The adsorption of 125I-AT1 to heparin-agarose was inhibited by prior incubation of solubilized receptor with heparin or PVS. These results suggest that All-induced steroidogenesis is mediated by a DuP-753-sensitive receptor and that PVS decreases the affinity of this receptor by interacting with an intracellular domain (possibly the positively charged domain responsible for coupling with guanine nucleotide-binding proteins).

Inositol 1,4,5-trisphosphate (InsP3) is an intracellular messenger generated upon stimulation of a wide variety of cells by Ca2(+)-mobilizing stimuli. Specific binding sites for InsP3 have been identified in the adrenal cortex and many other tissues. The purpose of the present study was to solubilize and further characterize InsP3 receptors of bovine adrenal cortex. When adrenal cortex microsomes were incubated with Triton X-100 (1%) for 45 min and centrifuged at 100,000 x g for 1 hr, substantial InsP3-binding activity was recovered in the pellet fraction (82 +/- 46 fmol/mg of protein; Kd of 2.7 +/- 1.2 nM), suggesting a possible association with the cell skeleton. Similar results were also obtained with a microsomal preparation of rat cerebellum. On the other hand, the supernatant fraction also displayed important InsP3-binding activity (188 +/- 67 fmol/mg of protein; Kd of 10.4 +/- 2.2 nM). InsP3 binding in both fractions was inhibited by heparin and was increased upon pH elevations from 6 to 9. These are two characteristic properties of InsP3 receptors. Solubilized InsP3 receptors displayed a molecular size around 1,000,000, as estimated by gel filtration through Sepharose-4B column. Radiation inactivation analyses of the receptors of bovine adrenal cortex and rat cerebellum revealed unusual inactivation curves, indicating binding domains of Mr 65,000, much smaller than the smallest covalent structure (subunit) of Mr 260,000 estimated by gel electrophoresis. These results suggest that the binding domain of the receptor behaves independently from the rest of the molecule and that a direct hit on the domain is needed for inactivation. Our data show that the binding sites for InsP3 in the adrenal cortex have properties similar to those of sites recently purified from rat cerebellum, and they suggest that InsP3 receptors from both sources might be the same molecular entity.

Leukotriene (LT) C4 receptors have been characterized on freshly isolated guinea pig tracheal epithelial cells (tracheocytes). The [3H]LTC4 receptor affinity was enhanced by increasing the sodium (60-160 mM) and the magnesium (0-10 mM) concentrations. Low concentrations of calcium (0-3 mM) increased [3H]LTC4 binding, but high concentrations (3-10 mM) decreased it. The pH (6.5-8.0) had no effect on [3H]LTC4 binding to tracheocytes. Under our experimental conditions, binding equilibrium was reached after 20 min. The association and the dissociation rate constants were estimated to be 2.75 +/- 0.25 x 10(6) M-1.min-1 and 0.093 +/- 0.008 min-1, respectively. The Kd (35.4 +/- 8.6 nM) and the Bmax values (2.4 +/- 0.6 x 10(5) receptors/cell) were determined by Scatchard analysis. LTB4, LTD4 and LTE4 did not inhibit [3H]LTC4 binding to the receptors. However, the compound FPL 55712 inhibited the binding of [3H]LTC4 with an IC50 value of 9.0 +/- 1.0 microM. [3H]LTC4 was not metabolized during the binding assays, as confirmed by reverse-phase high-performance liquid chromatography. The lack of [3H]LTC4 binding to glutathione-S-transferase was demonstrated in the presence of an excess of reduced glutathione. LTC4 produced a concentration-dependent increase of free Ca++ in tracheocytes. Our results suggest that guinea pig tracheocytes possess a specific LTC4 receptor coupled to a Ca++ signaling pathway. This LTC4 receptor may play a key role in the epithelium-dependent responses of airway smooth muscle.

High-resolution computerized tomography (CT) has been used to investigate abnormalities of the ear and petrous bone. Congenital, traumatic, infective and neoplastic lesions have been evaluated in 30 patients with proven pathology. Some bone changes including abnormalities of the auditory ossicles have been better demonstrated than by conventional tomographic techniques, and high-resolution CT has some advantages in demonstrating both soft tissue abnormality and bone changes in the middle ear in primary neoplastic disease and secondary cholesteatoma. The absence of any practical means of taking sagittal sections with the present scanner design limits the usefulness of high resolution CT of the petrous bone, but this study has shown that the technique may now take its place as an important complementary procedure to pluridirectional tomography.

Regional cerebral blood volume (rCBV) was measured in 14 patients with normal CT scans. An EMI CT 1010 scanner was used in combination with a computer subtraction technique. The mean CBV in the cortex was 5.0 ml/100 ml of tissue and 2.2 in the white matter. Regional differences were not significant and no difference was found between the right and left hemispheres.

Most applications of Bayes theorem in computer-aided diagnosis have been to situations involving the differential diagnosis of a small list of disease categories. In the case of the diagnosis of cerebral tumours, if each tumour type in each main anatomical situation is counted as a single diagnosis, there are about 100 possible disease categories. This paper investigates a method of incorporating expert prior information into the computer-aided diagnosis process so that this large number of categories can be handled.

A computerized subtraction technique has been described to measure regional cerebral blood volume (rCBV) using the EMI-Scanner in a group of 13 patients. Sodium iothalamate was injected intravenously (1·75 ml./kg) to increase the absorption of X rays in the cerebral circulation. Significant regional differences in CBV were shown, values in the frontal and temporal regions being lower than the mean hemisphere value (4·9 ±0·7) and higher in the occipital region. The left hemisphere showed a significantly higher CBV when compared with the right. Measurements of CBV in the cortex showed no regional variation, but the mean cortical value of 6· 0 ± 1· 8 was significantly higher than the hemisphere mean.

Conventional rapid serial angiography and isotope clearance (intracarotid 133Xe) have been combined in the study of 21 patients with completed strokes and 14 with transient ischaemic attacks. Angiography revealed disturbed flow in over half the cases; it correlated reasonably well with the results of isotope clearance, more so in the case of fast flow on angiography with high flow on isotope clearance than in the case of slow flow on angiography with low flow on isotope clearance. The use of isotope studies revealed some areas of flow disturbance not shown by angiography, particularly in cases with transient ischaemic atatcks. The case for combined angiography and isotope clearance is argued for cases in which flow disturbance is thought likely to be present.

The use of a computer to assist the diagnosis of intracranial tumours was described by the present authors in 1968. Subsequent work has been concerned with improving the accuracy of the diagnostic program by experimental weighting of more important radiological signs (du Boulay, Popple, and Price 1969) and with the addition of proven cases to the computer's file of data.From the beginning of these studies a second program has been in operation. Its purpose has been to choose, by comparison with past proven cases, what should be the “next test” (in previous publications spoken of as the “next best test”). This next test, carotid angiography for instance, will be seen to be “best” if it can be shown statistically by comparison with previous patients that it is the most likely test to discriminate between the three most probable diagnoses.Theory of the method incorporated in the second program at present is based on the three diagnoses (denoted by i1, i2and i3) which have been given the highest probability by the first program. For each of these values of iand for each investigation, J, not yet made on the new patient the computer calculates: wherej= a basic test, i.e.an individual sign such as pineal displacement, obtained by doing a comprehensive test, e.g.plain film.Nij= total number of patients with the ith type of tumour on whom the jth test was made.

The sella turcica and some other features of the skulls of 25 cases of aqueduct stenosis and 16 cases of communicating hydrocephalus were investigated.Communicating hydrocephalus produces very little pressure change in the sella. It sometimes causes elongation.Aqueduct stenosis in adults results often in a characteristic deformity of the sella, and in nearly all adults there are other alterations of the skull as well.

The dorsum sellae has been studied in 104 elderly subjects without evidence of intracranial disease and in 56 patients with severe hypertension. A high-definition technique has been used.In all of the elderly patients the cortex of the anterior aspect of the dorsum (lamina dura) was intact. It is concluded that an intact lamina dura is a good indication of a normal sella. It enables a distinction to be made between the appearances of old age and the early changes of raised intracranial pressure.In four of the hypertensive patients, changes were seen which were indistinguishable from those of raised intracranial pressure.

The histories, radiographs and, where relevant, the operation notes and pathological findings in 197 cases of intracranial aneurysm have been reviewed in order to throw light on the natural history of the disease.It is concluded that the earliest changes of atherosclerosis are closely associated with the formation of aneurysms and that their subsequent history depends upon a balance between healing processes and advanced atheroma.Grounds are given for discounting the importance of defects in the muscular coat of intracranial arteries in this disease.Sudden (sometimes silent) changes in size and shape may be demonstrated as well as slower ones. Some emphasis is placed upon the benign course of the disease in a proportion of patients and the possibility of permanent healing in others after subarachnoid haemorrhage.The serious significance of loculation is underlined.There are sex differences not only in the demonstration of symptom-producing aneurysms, but also in the natural history of the disease. At first equally proportioned between the sexes or perhaps commoner in men, aneurysms become both commoner and less stable in women in early middle age.This instability manifesting itself by loculation and/or haemorrhage persists through the next three decades. On the other hand large aneurysms with their rather different natural history (fewer subarachnoid haemorrhages, but greater tendency to brain damage) are less uncommon in men.

Telecine has been a routine tool in the investigations of pneumoencephalography and myelography for a number of years. Details of the technical means by which adequate film is ensured are described.Future possibilities in automatic control of the tube current are mentioned.

Seven case are presented; some show typical tentorial branches from the internal carotid arteries in cases of meningioma and arteriovenous malformation: one illustrates the practical importance of recognising the presence of this artery, and one shows a perhaps hitherto undescribed variation of the origin of two left-sided tentorial arteries. Cases of astrocytoma, haemangioblastoma and of cerebral secondary deposits illustrate the fact that any vascular lesion in the region of the tentorium may cause hypertrophy of the tentorial arteries.

The radiographs and notes of 388 patients suffering from ntracranial tumours at a distance from the sella have been reviewed. An additional 212 patients with intracranial tumours were reviewed simply to record the position of the anterior end of the 3rd ventricle and the condition of the pituitary fossa.Various changes in the sella and its vicinity due to raised intracranial pressure may be classified into three categories. This classification provides some limited help in the localisation of tumours.Twenty per cent of patients with pressure changes in the sella due to tumours at a distance from the sella do not have papilloedema. Many of these tumours are slow-growing and benign and first-class radiography is of great importance in discovering them.A mechanism which may operate in causing erosion of the lamina dura is suggested.

The radiographs of 299 captive primates have been examined and an association demonstrated between nutritional bone disease and the development of spondylosis.There are some indications of a similar tendency among captive carnivores.

Detailed observations of pulsatile movements within the cranial and spinal CSF spaces have been made at myelography, pneumoencephalography and Myodil ventriculography; most of them on normal or near-normal patients; but some in cases of obstruction.The effects of the pulsatile movement on CSF circulation, on cyst formation and in cases of obstruction, particularly at the foramen magnum and tentorial opening, are discussed.

A computer program is described whereby the diagnosis of an intracranial tumour may be made from the probabilistic basis by comparison with previous patients. The data employed are signs elicited by radiological examination. A second program predicts the next most informative test not yet performed, e.g., vertebral angiography. Some early results are encouraging.

le May and Jackson in this issue report a cervical disc protrusion which was not revealed by positive contrast myelography in the prone position, but gave the false appearance of an intramedullary tumour and they go on to explain how this may happen.The two cases of meningioma in front of the cord described in the present paper bear some similarity to le May and Jackson's case because of the myelographic difficulties encountered. Both, in addition to this invisibility of the tumour in the prone position at head-down tilting, have it in common that an abnormality was shown by screening in the supine position. Moreover this abnormality might well be, and was in one instance, mis-interpreted as showing a posteriorly placed mass.H. W., a 74-year-old man, referred for X-ray examination at St. Bartholomew's Hospital complained of pain in the left shoulder and back of his head, difficulty in walking and numbness of the left side of his body.Two years previously he had developed pain and stiffness in the left shoulder radiating to the left side of the occiput. The pain was constant and worse when lying in bed. Coughing caused the pain to spread down to the fingers of both hands, first on the left and then on the right. Numbness gradually spread up the arms and more recently had involved the left leg. There was no sphincter disturbance.