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Biomedical subjects

G Campbell

Publications and source records attributed to G Campbell.

At least 199 records · Page 11Linked to original sources
PubMed1985

Role of extracellular proteins in the dynamics of vasogenic brain edema.

The relationship between extravasation of proteins into extracellular spaces of brain parenchyma and the water content of such regions were evaluated in an experimental model. In this model, a temporary opening of the blood-brain barrier (BBB) to proteins was produced without significant injury to the cellular elements of brain tissue. Rabbits were subjected to bolus injection of their own blood under 360-400 mm Hg pressure via the internal carotid artery. The opening of the barrier and its duration were evaluated with Evans blue (EB), horseradish peroxidase (HRP), and sodium fluorescein (NaFl) tracers. The water content of brain tissue was assessed by specific gravity (SG) measurements in 1-mm-diameter tissue samples. Quantitative evaluation of protein penetration into brain tissue was carried out using 125I bovine serum albumin (BSA). The opening of the BBB to proteins persisted up to 9 h, whereas the barrier remained permeable to small molecular NaFl for 24 h. The SG measurements indicated in the areas of EB extravasation a progressive increment in water content up to 9 h, i.e., the duration of BBB opening to proteins. Following this, there was a progressive clearance of edema in spite of the BBB remaining open for NaFl for 24 h. Quantitative evaluations of 125I-BSA and SG in the same tissue samples, supported by statistical analysis, indicated approximately linear relationship analysis, indicated approximately linear relationship between albumin and water, implying a strong correlation between the development of vasogenic edema and extravasation of proteins into extracellular spaces.

Animals↗
PubMed1985

The synergism of n-hexane-induced neurotoxicity by methyl isobutyl ketone following subchronic (90 days) inhalation in hens: induction of hepatic microsomal cytochrome P-450.

The effect of methyl isobutyl ketone (MiBK) on n-hexane-induced neurotoxicity was investigated via inhalation in seven groups of five hens each for 90 days followed by a 30-day observation period. One group was exposed to vapors containing 1000 ppm n-hexane and another group to vapors having 1000 ppm MiBK. Four groups were exposed simultaneously to 1000 ppm of n-hexane and 100, 250, 500, or 1000 ppm MiBK. Another group was exposed similarly to ambient air in an exposure chamber and used as a control. Hens continuously exposed to 1000 ppm MiBK developed leg weakness with subsequent recovery, while inhalation of the same concentration of n-hexane produced mild ataxia. Hens exposed to mixtures of n-hexane and MiBK developed clinical signs of neurotoxicity, the severity of which depended on the MiBK concentration. Thus, all hens exposed to 1000 ppm n-hexane in combination with 250, 500, or 1000 ppm MiBK progressed to paralysis. Hens continuously exposed to 1000/100 n-hexane/MiBK showed severe ataxia which did not change during the observation period. The neurologic dysfunction in hens exposed simultaneously to n-hexane and MiBK was accompanied by large swollen axons and degeneration of the axon and myelin of the spinal cord and peripheral nerves. The results indicate that the nonneurotoxic chemical MiBK synergized the neurotoxic action of the weak neurotoxicant n-hexane since the coneurotoxicity coefficient for joint exposure was more than two times the additive effect of each treatment alone. In another experiment, to investigate the mechanism of MiBK synergism of n-hexane neurotoxicity, continuous inhalation for 50 days of 1000 ppm n-hexane had no effect on hen hepatic microsomal enzymes, whereas inhalation of 1000 ppm MiBK for 50 days or a mixture of 1000 ppm of each of n-hexane and MiBK for 30 days significantly induced aniline hydroxylase activity and cytochrome P-450 contents in hen liver microsomes. Liver microsomal proteins from these hens and from hens treated with beta-naphthoflavone (beta-NF) and phenobarbital (PB) were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. While beta-NF increased the 55-kDa band (1408%), PB, MiBK, and MiBK/n-hexane increased the protein band (49 kDa) (258, 335, and 253%, respectively), indicating that MiBK induces chicken hepatic cytochrome P-450. The results suggest that the synergistic action of MiBK on n-hexane neurotoxicity may be related to its ability to induce liver microsomal cytochrome P-450, resulting in increased metabolic activation of n-hexane to more potent neurotoxic metabolites.

Aniline Hydroxylase↗
PubMed1985

Identification of synapses formed by the aberrant, uncrossed retinogeniculate projection in the hamster after neonatal monocular enucleation.

The terminals of the abnormally enhanced, stabilized uncrossed retinogeniculate projection in adult hamsters produced by removal of one eye at birth, were labelled by injection of HRP into the remaining eye and examined by electron microscopy. Labelled terminals closely resembling normally positioned retinal terminals were found to make well-differentiated synaptic contacts with geniculate projection and interneuron-like cells in regions of the dorsal lateral geniculate nucleus that do not receive uncrossed retinal input in normal adult animals.

Animals↗
PubMed1985

Variants of polyoma-transformed BHK21 cells unresponsive to fibronectin.

To investigate the relation between cell-substratum adhesion and cell-spreading we have isolated variants of anchorage-independent cells which fail to adhere to fibronectin. The variants are poorly adhesive both to fibronectin and serum, show dramatically altered morphology in culture and are unable to spread on any protein-coated surface yet tested.

Animals↗
PubMed1985

Enhanced cerebral substrate pools in the fetus and neonate of the diabetic canine mother.

Energy stores and intermediates of carbohydrate metabolism were investigated in the freeze-clamped cerebral cortex of the fetus and fasted neonate born to a diabetic canine mother. Prior studies in these same pups demonstrated circulating hyperinsulinemia, depressed free fatty acid levels, and attenuated gluconeogenesis. Hepatic and muscle tissue also demonstrated augmented levels of glycogen, triglycerides, and amino acids. In the present investigation, cerebral tissue from these same pups of diabetic mothers also demonstrated enhanced fetal cerebral glucose and glycogen content. After 24 h of neonatal fasting, cerebral glycogen content declined to values lower than in control pups. Cerebral cortical levels of glucose-6-phosphate, fructose-6-phosphate, lactate, citrate, alpha-ketoglutarate, and malate were not altered, while oxaloacetate was higher at 3 and 9 h and fructose-1,6-diphosphate was higher at 9 and 24 h in the IDM pups. Adenine nucleotide levels and the energy charge were equivalent to those in control pups at each time interval. In contrast, cerebral cortical amino acids of the glutamate group were enhanced in the fetus or neonate of the diabetic mother. Cerebral cortical alanine was increased from 3 to 24 h while aspartate and glutamate were augmented in the fetus and fasted IDM newborn pup. Glutamine was increased at 6 and 24 h, while gamma-aminobutyrate was elevated in the fetus. Cerebral ammonia concentration was not altered. The augmented stores of cerebral carbohydrate and amino acid pools in the fetus and neonate after maternal canine diabetes may serve as oxidizable substrates for the brain during periods of attenuated systemic fuel availability.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine↗
PubMed1984

Evidence for 5-hydroxytryptamine in neurones in the gut of the toad, Bufo marinus.

The stomach, small intestine and large intestine of the toad, Bufo marinus, were processed for formaldehyde-induced fluorescence histochemistry. After extrinsic denervation or pretreatment with 6-hydroxydopamine to remove catecholamine fluorescence, yellow fluorescence typical of 5-hydroxytryptamine was observed in neurones in the small intestine only. The cell bodies and their processes were confined to the myenteric plexus. Additional pretreatment with 5-hydroxytryptamine enhanced the fluorescence of neurones in the small intestine and revealed yellow-fluorescent nerve fibres, but not cell bodies, in the longitudinal and circular muscle layers and myenteric plexus of the large intestine. No fluorescent neurones were observed in the stomach. Following reserpine treatment, which removed native yellow fluorescence in the small intestine, exposure to 5-hydroxytryptophan produced yellow fluorescence in axons in both small and large intestine; exposure to tryptophan never restored fluorescence. The neurotoxin, 5,7-dihydroxytryptamine had no effect on the distribution of yellow-fluorescent neurones in the small and large intestine. No 5-HT-containing mast cells were present in either the small or large intestine. Thin layer chromatography with three different mobile phases showed a 5-hydroxytryptamine-like compound in extracts of mucosa-free small and large intestine but not of stomach.

Animals↗
PubMed1984

Postnatal development of ipsilateral retino-geniculate projections in normal albino rats and the effects of removal of one eye at birth.

The postnatal development of ipsilateral retinofugal projections to the lateral geniculate body in normal albino rats, and in rats unilaterally enucleated at birth has been examined. At postnatal ages ranging from 1 day to 6 months, horseradish peroxidase was injected into one eye of normal rats and into the remaining eye of neonatally enucleated animals. After approximately 20 hours, the animals were perfused, the brains sectioned and reaction product visualised using tetramethylbenzidine. Ipsilateral retinal projections to the lateral geniculate body in normal animals were extensive on postnatal day 1 and became reduced over the next few days, the adult pattern being established between days 9 and 12. In the enucleated group, the terminal fields of the ipsilateral projections to the lateral geniculate body from the remaining eye remained larger and displayed a greater density of terminal labelling than in age-matched controls. In addition, the ipsilateral terminal field in the dorsal lateral geniculate nucleus occupied a more lateral position than in control animals. These findings support previous suggestions that the abnormally large ipsilateral retino-fugal projections observed in adult rats following removal of one eye, at or close to, birth, result from a failure of the ipsilateral projection to become restricted and that terminal or preterminal sprouting of retinal axons may also make a small contribution to the formation of the exuberant ipsilateral projection.

Animals↗
PubMed1984

Normal postnatal development of retinogeniculate axons and terminals and identification of inappropriately-located transient synapses: electron microscope studies of horseradish peroxidase-labelled retinal axons in the hamster.

Axons from the eyes reach the dorsal lateral geniculate nucleus of the hamster at birth and both crossed and uncrossed axons spread throughout the nucleus within which they overlap extensively between postnatal days 2-6, before segregating to terminate in different parts of the nucleus by days 8-10 [So, Schneider and Frost (1978) Brain Res. 142, 343-352]. We have labelled retinal axons and their terminations between the day of birth (day 0) and day 6 by injecting one eye with horseradish peroxidase a few hours prior to sacrifice. Labelled profiles were then systematically sought, identified and their position determined, by electron microscope study of large frontal thin sections of both dorsal lateral geniculate nuclei. Labelled crossed and a few labelled uncrossed axons were present at day 0 and became progressively more common over the following few days; appropriately-located labelled uncrossed axons and terminals in the centromedial part of the nucleus (future ipsilateral sector) were relatively less common than labelled crossed axons in the ventrolateral part of the nucleus (part of the future contralateral sector), particularly between days 0 and 3. Synaptic contacts established by such labelled axons were characterized by predominantly electron-lucent spherical presynaptic vesicles and a prominent postsynaptic density. At day 4, labelled uncrossed axons made synaptic contact in the future contralateral sector (which is devoid of uncrossed input after days 8-10) and a few crossed axons made synaptic contacts in the future ipsilateral sector (devoid of crossed input after days 8-10). Such terminals and their synaptic contacts, were identical to appropriately-located ones in the same material. Inappropriately-located terminals were not found in the future contralateral sector at day 6, or in adults. No specialized contacts were observed between inappropriately-located axons or terminals and either other axon terminals or glial cell processes. Thus, during the development of the hamster retinogeniculate projection, inappropriately-located axons establish transient synaptic contacts with geniculate cells, and these contacts are lost as the segregated adult pattern of projections is established.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Osteoid in bones of elderly patients without bone disease.

Bone samples were taken at post-mortem examination by Jamshidi needles from 88 elderly patients who were known to have normal bone biochemistry in life. The extent of osteoid in these samples is quantitatively described. In patients with normal creatinines the relative osteoid area ranges from 0 to 3.7% and trabecular osteoid surface percentage ranges from 0 to 23%, but higher values were seen in those with raised creatinines. Osteoid extent did not vary with age, sex or time of year. Descriptions of other series of control bone biopsies in the literature are reviewed and it is suggested that relative osteoid area greater than 3.5% or osteoid surfaces greater than 25% should be considered excess osteoid.

Aged↗
PubMed1984

Relation between gastric histology and gastric juice pH and nitrite and N-nitroso compound concentrations in the stomach after surgery for duodenal ulcer.

Formation of N-nitroso compounds in gastric juice has been implicated in the pathogenesis of cancer in the stomach after operation. Gastric juice was aspirated from 85 subjects: 23 were controls, 51 had previously undergone vagotomy and gastrojejunostomy, and 11 had previously undergone vagotomy and pyloroplasty. The gastric juice samples were analysed for pH, nitrite, and total N-nitroso compounds. A significant correlation was found between pH and nitrite concentration (p less than 0.01). No significant correlation was found between pH and total N-nitroso compound concentration or between nitrite and N-nitroso compound concentration. The vagotomy and gastrojejunostomy patients had higher pH values and higher concentrations of nitrites and N-nitroso compounds than controls (p = 0.01 in all cases). The 51 vagotomy and gastrojejunostomy patients also underwent endoscopy and biopsy. They were divided into three groups: group 1 (21 patients) had no intestinal metaplasia and no more than mild dysplasia; group 2 (20 patients) had intestinal metaplasia; and group 3 (10 patients) had moderate or severe dysplasia. Groups 2 and 3 both had higher pH values and higher nitrite concentrations than group 1 (p = 0.01 in all cases). There was no significant difference, however, between either group 2 or 3 and group 1 for total N-nitroso compound concentration. Since there was no simple linear relation between pH and N-nitroso compound concentration, it was concluded that formation of N-nitroso compounds at high pH was unlikely to be involved in the pathogenesis of gastric cancer in the hypochlorhydric stomach after operation. The relation between nitrite and histological abnormality was not associated with a similar relation between N-nitroso compounds and histological abnormality. It therefore appears that there is no simple relation between N-nitroso compounds and the pathogenesis of premalignant gastric mucosal changes.

Duodenal Ulcer↗
PubMed1983

Otoplasty: something old, something new. Reconstruction of the external ear using fresh cadaver homograft ear cartilage and a sternomastoid myocutaneous flap.

By combining the very old concept of using fresh cadaver homograft ear cartilage with the more modern idea of a musculo-cutaneous flap, a new ear has been constructed for a patient who was considered unsuitable for standard reconstructive procedures. The early cosmetic result appears satisfactory and the patient's hearing has been significantly improved.

Adult↗
PubMed1982

Somatostatin is contained in and released from cholinergic nerves in the heart of the toad Bufo marinus.

The heart of the toad Bufo marinus contained a substance with somatostatin-like immunoreactivity which eluted with somatostatin on reverse phase high pressure liquid chromatography. Immunoreactivity to somatostatin was localised histochemically to nerve fibers in muscle bundles of the sinus venosus, atria and ventricles and to nerve cell bodies in the sinus venosus and inter-atrial septum. Nerve cell bodies were localised both by interference contrast microscopy and immunohistochemistry; all detectable intracardiac neurons were immunoreactive. Synthetic somatostatin inhibited the rate and force of beat of atrial preparations, but did not affect the driven ventricle. Vagal stimulation caused inhibition of all cardiac chambers. After muscarinic blockade with hyoscine, vagal stimulation with 3 Hz or more still caused inhibition of the pacemaker and atrium, but not of the ventricle. The hyoscine-resistant vagal effects were diminished by about 60% after induction of tachyphylaxis to somatostatin. When when the vagus nerves were stimulated intermittently for 1 h at 10 Hz, in the presence or absence of hyoscine, the effect of somatostatin was reduced by about 60%. It is concluded that the cholinergic postganglionic neurons of the cardiac vagus contain somatostatin. When the vagus is stimulated at 3 Hz or more, the neurons release sufficient somatostatin to inhibit the pacemaker and atrial muscle.

Animals↗
PubMed1982

Computed tomography and bone scintigraphy in the evaluation of tarsal coalition.

Three cases of talocalcaneal coalition were evaluated with routine radiography, conventional tomography, 99mTc-MDP bone scintigraphy, and computed tomography (CT). Routine radiography was normal in 1 case and demonstrated secondary findings suggesting coalition in 2. Conventional tomography confirmed the coalition in 2 patients. In all 3 cases, the scintigrams demonstrated increased uptake in the region of the coalition. CT provided the most graphic depiction of the coalition site and also identified an associated lesion involving the posterior subtalar joint, not recognized on conventional tomography. Scintigraphy may be useful as a screening procedure and can provide important localizing information in difficult cases.

Adult↗