Search PubMed⌕ Search

Biomedical subjects

D H Jones

Publications and source records attributed to D H Jones.

At least 217 records · Page 12Linked to original sources
PubMed1980

The biochemical diagnosis, localization and follow up of phaeochromocytoma: the role of plasma and urinary catecholamine measurements.

The diagnosis of phaeochromocytoma is dependent on combined biochemical and radiological investigation, the biochemical studies being performed initially and followed later by both non-invasive and invasive radiological techniques. In 23 patients studied, a selection of biochemical studies allowed diagnosis and accurate localization of phaeochromocytoma in 16. In some patients, tumour localization was confirmed by radiographic methods. Biochemical estimations of catecholamines and/or metabolites in urine and/or plasma were also performed during and after operation, and these measurements allowed monitoring of the completeness of tumour excision, and of the possibility of recurrence, in both the short term and the long term follow up of patients.

Adrenal Gland Neoplasms↗
PubMed1979

Aggregations of synaptic vesicles on the exposed inner membrane of presynaptic mitochondria in brain.

Fragments of rat cerebral cortex have been incubated under various conditions. When divalent cations are present, patches of the external membrane of some mitochondria are disassembled leaving the inner mitochondrial membrane exposed to the cytoplasm. Sometimes the entire external membrane is missing. In presynaptic bulbs the synaptic vesicles are attracted and adhere to the exposed outer face of the inner mitochondrial membrane. The mode of attraction and adhesion of the vesicles is discussed. Possibly this could serve as a model for further investigation of the attraction of vesicles to the active zone of the presynaptic membrane.

Animals↗
PubMed1979

Immunohistochemical localization of neurofilament antigen in rat cerebellum.

The distribution of neurofilaments in the rat cerebellar cortex was studied by immunoperoxidase histochemistry using an antiserum raised against neurofilaments isolated from brain (anti-NF). In light microscope preparations, this antiserum selectively stained known neurofilament-containing structures. Staining was most intense in myelinated axons of the white matter and in the terminal branches of basket cell axons. No staining was apparent in either neuronal or glial cell bodies or in glial cell processes. These findings were confirmed in electron microscopic preparations of the same material. Neurofilaments stained by the antiserum were abundant in basket cell axons and also occurred in small bundles in mossy fibre terminals. Adjacent microtubules were not stained by the antiserum. There was no evidence of stained cytoplasmic filaments in glial cell processes. Thus it appears that neurofilaments contain unique antigens which do not occur in either microtubules or in glial cytoplasmic filaments. The antiserum did not induce staining of synaptic junctional structures, a result which contradicts previous suggestions that neurofilaments are structural components of synaptic densities.

Animals↗
PubMed1979

Choice of control groups in the appraisal of sympathetic nervous activity in essential hypertension.

1. Plasma noradrenaline concentrations were similar in normotensive and hypertensive outpatients, but were significantly lower in laboratory control subjects. 2. Standing plasma noradrenaline concentrations were similar in all three groups. 3. Urinary vanillyl mandelic acid, catecholamines and metanephrines were also similar in the normotensive and hypertensive groups. 4. Laboratory controls, possibly because of familiarity with the techniques of sphygmomanometry and blood sampling, may attain a 'basal' resting level of sympathetic nervous discharge more readily and rapidly than subjects who are unfamiliar with such procedures. 5. After orthostatic stimulation by standing for 2 min, the activity of the sympathetic nervous system, as determined by pulse rate and plasma noradrenaline concentrations, was similar in the three groups, despite the lower starting values in the laboratory staff. 6. The absence of differences in plasma noradrenaline or urinary catecholamine and metabolite concentrations does not support the hypothesis of excessive sympathetic nervous activity in essential hypertension.

Humans↗
PubMed1979

Plasma noradrenaline concentrations at different vascular sites during rest and isometric and dynamic exercise.

1. Blood samples were obtained simultaneously from femoral artery and vein, pulmonary artery and antecubital vein at rest and during isometric and dynamic exercise in six patients during cardiac catheterization and plasma noradrenaline was measured radioenzymatically. 2. Analysis of variance indicated that differences between vascular sites were not significant, whereas differences between patients (P less than 0.001) and differences between activities (P less than 0.001) were significant. 3. Mean systemic arterial concentrations tended to be lower than pulmonary arterial concentrations during each activity, although the difference was not significant. 4. We conclude that forearm venous plasma noradrenaline concentrations are representative of those from other sites.

Adult↗
PubMed1979

Selective venous sampling in the diagnosis and localization of phaeochromocytoma.

Plasma noradrenaline levels were measured at several sites in the systemic venous system by selective catheterisation in ten hypertensive patients in whom phaeochromocytoma was suspected on clinical or biochemical grounds. Four patients had localized noradrenaline elevation and the diagnosis of phaeochromocytoma was confirmed at operation. The remaining six patients demonstrated no localized elevation of noradrenaline and there has been no evidence of a tumour on follow up. The technique allows the diagnosis and accurate localization of phaeochromocytoma and is useful in excluding the tumour in patients with essential hypertension.

Adrenal Gland Neoplasms↗
PubMed1979

Avian metabolism of halogenated biphenyls.

1. The metabolism of several halogenated biphenyls has been studied using poultry as a model system. The substrates 4-chlorobiphenyl and 4-bromobiphenyl each yielded two metabolites (4'-chloro-4-biphenylol, 4'-chloro-3,4-biphenyldiol; 4'-bromo-4-biphenylol, 4'-bromo-3,4-biphenyldiol), while 4,4'-dichlorobiphenyl yielded only one metabolite (4,4-dichloro-3-biphenylol). 2. Metabolites were not found in eggs collected for 7 days following the administration of the substrate.

Animals↗
PubMed1978

Plasma noradrenaline, age and blood pressure: a population study.

1. Mean supine plasma noradrenaline was lower in 12 male laboratory staff (0.24 +/- 0.02 microgram/l) than similarly normotensive out-patients (0.44 +/- 0.07 microgram/l). 2. In 164 non-medical hospital staff, plasma noradrenaline increased with age in white males only. 3. Plasma noradrenaline was significantly higher in women than men. 4. There was no relationship between supine blood pressure and plasma noradrenaline in normotensive or hypertensive subjects.

Adult↗
PubMed1978

Sympathetic nervous function and renin activity in hypertensives on long term drug treatment with propranolol, methyldopa or bendrofluazide.

Plasma noradrenaline and plasma renin activity were measured as indices of sympathetic activity and renin angiotensin system in similar groups of hypertensive patients receiving either propranolol, bendrofluazide or methyldopa. Plasma renin activity was similar in the propranolol and methyldopa groups and significantly lower (p less than 0.01) in both these groups than the diuretic treated subjects. Plasma noradrenaline was significantly lower (p less than 0.01) on methyldopa than either propranolol or bendrofluazide. These different effects on the renin angiotensin system and the sympathetic nervous system of these drugs may be relevant in the choice of long term therapy in hypertension.

Adult↗
PubMed1977

Free and total 3-methoxy-4-hydroxyphenylethylene glycol in human cerebrospinal fluid: relationship to blood pressure in hypertensives and patients with neuropsychiatric disease.

The concentrations of free and total 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) in the cerebrospinal fluid of 43 patients were measured by selected ion monitoring gas chromatography-mass spectrometry using MHPG specifically labelled with deuterium as internal standard. Unpaired Wilcoxon comparisons of free and total MHPG concentrations in males and females showed no significant difference between the sexes. The relationships between free, conjugated and total MHPG concentrations and age, blood pressure, glucose and protein levels in cerebrospinal fluid were examined by linear regression analysis. The only significant correlations found were between free MHPG and glucose and between total MHPG and glucose.

Adolescent↗
PubMed1976

Developmental changes in mitochondria during the transition into lactation in the mouse mammary gland.

Mitochondrial biogenesis in the parenchymal cell of the mouse mammary gland appears to occur in two distinct phases: replication during cell proliferation, and maturation during cell differentiation. This study of the mitochondrial maturation phase in the mouse gland demonstrates a significant increase in organelle density on isopycnic sucrose gradient centrifugation during the transition from late pregnancy to day 8 of lactation. Differential fragility to high sucrose concentrations or changes in mitochondrial lipid composition do not satisfactorily explain the density increases. When organelle densities were assessed by centrifugation under iso-osmotic conditions with Ficoll gradients in 0.25 M sucrose, the mitochondria from pregnant glands were observed to be more dense than those from lactating glands. The two mitochondrial populations were also found to differ in their response to changes in sucrose concentration in the Ficoll gradients. When sucrose concentration was increased, the density of both pregnant and lactating gland mitochondria increased nonlinearly, the increase being greater with the lactating gland organelles. By use of mathematical models, the differing response was interpreted as a change in the density and osmotic activity of the mitochondrial internal compartment (inner membrane plus matrix space). We have proposed that the changes reflect a large expansion of the inner mitochondrial membrane and perhaps the matrix material during the transition into lactation in the differentiating parenchymal cell.

Animals↗
PubMed1976

Developmental changes in mitochondria during the transition into lactation in the mouse mammary gland. II. Membrane marker enzymes and membrane ultrastructure.

The activity of cytochrome oxidase (an inner mitochondrial membrane marker) in mouse mammary gland homogenates was found to increase five- to sixfold from late pregnancy to day 8 of lactation, while that of monoamine oxidase (an outer membrane marker) increased only about 25%. The specific activity of cytochrome oxidase in the isolated mitochondria decreased slightly over the same period while the specific activity of monoamine oxidase decreased fivefold. This reflects the fact that both cytochrome oxidase and mitochondrial protein are increasing at a much greater rate than is monoamine oxidase activity. Mixing experiments preclude the possibility that the release or removal of an inhibitor or stimulator produces the changes in enzymatic activity. The cytochrome oxidase to monoamine oxidase ratio was followed throughout the pregnancy-lactation cycle in total mammary homogenates, isolated mammary parenchymal cells, and isolated mammary mitochondria. In each preparation the pattern was the same with little change in the ratio until late pregnancy; and then a three- to fourfold increase occurred and the values reached a maximum by day 8 of lactation. These experiments were interpreted as demonstrating that the observed enzymatic changes are reflective of alterations in the mitochondria of the mammary parenchymal cell population. Electron micrographs of mid-pregnant and mid-lactating mammary parenchymal cells in situ were prepared, and distinct changes in the mitochondrial morphology noted. The most significant and obvious change is the large increase in the number of inner membrane cristae and an increase in matrix density in the lactating gland cell. Therefore, both enzymatic and morphological studies support the concept of an expansion of the mitochondrial inner membrane during presecretory differentiation in the mouse mammary parenchymal cell.

Animals↗