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Biomedical subjects

D H Jones

Publications and source records attributed to D H Jones.

At least 235 records · Page 13Linked to original sources
PubMed1975

Junctional ultrastructure in isolated synaptic membranes.

The ultrastructure of synaptic junctions in whole brain tissue and isolated synaptic membranes has been compared. Type 1 junctions are present in the isolated membranes,readily identified by the presence of dense-staining material associated with the postsynaptic membrane, but the dense projections present at the presynaptic membrane in intact tissue are absent. Type 2 junctions are not easily recognized because of the absence of prominent junctional densities, but apposed membranes with the appearance of type 2 junctions are seen in isolated membrane preparations. Junctions without dense-staining material are also seen among SYNAPtosomes and survive the hypotonic conditions used during isolation of the membranes. It thus seems probable that both type 1 and 2 junctions are present in isolated synaptic membrane preparations. In type 1 junctions after isolation,the postsynaptic thickening and cleft substance are together seen to be composed of an array of 200 A dense-staining subunits spanning the postsynaptic unit membrane. The relationship of this structure to the ultrastructure of the cleft substance and postsynapticthickening in intact tissue is discussed.

Animals↗
PubMed1975

Diabetic complications in a patient with coexisting anterior hypopituitarism.

We present a patient who developed insulin-requiring diabetes several years after the onset of symptoms of anterior hypopituitarism. It is likely that the hypopituitarism protected him against the development of diabetic retinopathy and glomerular basement membrane thickening but not against neuropathy and atheroma. The significance of this in relation to the growth-hormone-microangiopathy hypothesis is discussed.

Aged↗
PubMedDate not supplied

The bacterial mutagenicity of nitropolychlorinated dibenzo-p-dioxins.

The bacterial mutagenicity of 2-nitrodibenzo-p-dioxin, a mixture of 2-nitro-7-chloro- and 2-nitro-8-chlorodibenzo-p-dioxin, 7-nitro-2,3-dichloro-, 8-nitro-2,3,7-trichloro-, 2-nitro-1,3,7,8-tetrachloro- and 3-nitro-1,2,4,7,8-pentachlorodibenzo-p-dioxin was determined using Salmonella typhimurium tester strains TA98 and TA100 with and without rat hepatic S9 for metabolic activation. All the nitro-PCDDs exhibited some direct-acting mutagenicity with both tester strains, however, the activity was significantly lowered in the presence of exogenous S9 and the compounds were more mutagenic to tester strain TA98. The mutagenicity of the nitro-PCDDs was also dependent on structure because there was a marked decrease in activity with increasing chlorine content. Because nitro-PCDDs have recently been identified as incomplete combustion products of municipal waste, this study confirms that this new class of compounds contains some bacterial mutagens.

Dioxins↗
PubMedDate not supplied

Adrenal tumour secreting vasoactive intestinal peptide and noradrenaline.

A patient with a ganglioneuroblastoma secreting both noradrenaline and vasoactive intestinal peptide is described. Their vasoactive effects are antagonistic and pre-operatively the patient was normotensive. Manipulation of the tumour provoked hypertension and after excision marked hypotension occurred which responded to the administration of metaraminol and blood. This case emphasises the need for thorough investigation of patients with amine or peptide-secreting tumours which have atypical features.

Adrenal Gland Neoplasms↗