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Biomedical subjects

A Garner

Publications and source records attributed to A Garner.

At least 145 records · Page 8Linked to original sources
PubMed1985

Malignant melanoma of the eyelid skin: histopathology and behaviour.

Histological sections from 24 patients with malignant melanoma of the eyelid skin were studied and correlated with clinical follow-up for an average of 8.6 years. There was an average post-treatment follow-up of 7.4 years with a cure rate of 78% in the superficial spreading group. The average follow-up in the nodular melanoma group was 9.4 years with a cure rate of 75%. Nodular melanoma patients with the lesion in the lid margin have a worse prognosis than those with the lesion on the eyelid skin.

Adolescent↗
PubMed1985

Polysulfone corneal inlays. Adverse reactions: a preliminary report.

The use of polysulfone to manufacture a lens for insertion into the corneal stroma to correct large refractive errors has been described. Two patients are presented in whom the procedure has been associated with significant loss of vision due to development of secondary changes in the cornea.

Adult↗
PubMed1985

Familial lecithin:cholesterol acyltransferase deficiency. Biochemistry of the cornea.

Opacification of the cornea from lipid accumulation is an early and characteristic feature of familial lecithin:cholesterol acyltransferase (LCAT) deficiency. Visual impairment in a female age 48 years led to keratoplasty and the first detailed analysis of cornea in this disorder. Multilaminar figures were present, and total lipid extracts were enriched with phospholipid and cholesterol; cholesteryl esters were reduced, and accounted for about 12% of the cholesterol. Linoleate C18:2 was the predominant residue in the cholesteryl ester fatty acid fraction, with a C18:1/18:2 ratio of 1:6.5. This ratio differs from that in normal cornea, and from that in plasma and in other tissue deposits in LCAT deficiency. Various disorders of the HDL/LCAT system in plasma can lead to corneal lipid accumulation and opacification. These disorders may share general defects of lipid clearance from the cornea, but this study of LCAT cornea indicates that the character of the accumulating lipid is significantly influenced by active local metabolism, irrespective of the defect in the HDL/LCAT system also present.

Chromatography, Gas↗
PubMed1984

Some characteristics of duodenal epithelium.

Duodenum is exposed to potential damage from acidopeptic secretions emptied from the stomach. In several mammalian species the duodenal mucosa was shown some 50 years ago to be better able to resist acid gastric juice than mucosa in more distal small intestine. Recent studies have identified HCO3- secretion originating from the surface epithelium, together with the ability of this epithelium to respond to intraluminal acid with a rise in HCO3- secretion, as important components of duodenal mucosal protection. Whether duodenal (Brunner's) glands also secrete some HCO3- is at present unknown. Secretion of HCO3- is stimulated up to 10-fold by the presence of luminal acid and is quantitatively sufficient to maintain neutrality at the mucosal cell surface at the lowest pH values encountered in the duodenum (approximately pH 2.0). Stimulation is mediated by mucosal production of prostaglandins, humoral factors and possibly neural mechanisms. The mucus gel adherent to the mucosa provides a physical basis for the standing pH gradient generated by epithelial HCO3- secretion. In vivo, mucosal blood flow supplies HCO3- to the epithelial cells and is particularly important at high (stimulated) rates of secretion.

Animals↗
PubMed1984

Immunocytochemistry of neuronal and glial markers in retinoblastoma.

An immunocytochemical study of 30 retinoblastomas was carried out using antibodies to neuronal and glial markers. The tumours were found to react with antibodies to neuron-specific enolase (NSE), a marker for neuronal elements, and S-100 and glial fibrillary acidic protein (GFAP), both of which are proteins present in glia. Two distinct cell populations were found within the tumour: the first, composed of anaplastic tumour cells at various stages of differentiation, showed both NSE and S-100 immunoreactivity; the second cell type, which immuno-stained for S-100 and GFAP, resembled mature glial cells. The results of this study indicate that the retinoblastoma may arise from a pluripotential primitive cell partially retaining neuronal and glial characteristics.

Eye Neoplasms↗
PubMed1984

Cell loss from human, canine and guinea-pig gastric mucosa measured by DNA radioimmunoassay.

A DNA radioimmunoassay, sensitive in the range 25-1000 ng, has been developed to measure gastric mucosal cell loss. Validity of the assay was based on antibody specificity, absence of interference from gastric contents, parallel tracer displacement by dilutions of gastric and standard DNA, and crossover with colorimetric assay. With this assay, gastric DNA shedding was examined in two animal species and man. In the guinea-pig stomach, DNA loss was 20-100 micrograms/h and in the canine Pavlov pouch, 260-580 micrograms/h. In the canine Pavlov pouch stimulation of acid secretion by histamine and exposure to exogenous acid increased DNA output. In the normal human stomach DNA loss was 544 +/- 175 micrograms/h and in duodenal ulcer patients, 649 +/- 225 micrograms/h. DNA radioimmunoassay provides a sensitive and reproducible measure of cell exfoliation from the stomach and may be a useful tool for studying aspects of gastric mucosal defence.

Animals↗
PubMed1984

A clinicopathological case of retinopathy of prematurity (ROP) treated by peripheral cryopexy.

A baby born at 25 weeks gestation with a birth weight of 800 g who suffered from severe respiratory distress syndrome with metabolic acidosis is described. Active retinopathy of prematurity, stages II and III, was found in the right eye at the age of 1 month and in the left eye a month later. Both eyes were treated by peripheral cryopexy. The pathological examination showed that cryopexy was effective in preventing progression of the retinopathy to cause severe cicatrisation.

Cryosurgery↗
PubMed1984

Severe ocular side effects of perhexilene maleate: case report.

We report a case of perhexilene maleate (PEXID) toxicity in which the presenting feature was loss of vision secondary to chronic papilloedema. Vortex keratopathy similar to that seen in amiodarone keratopathy was present, and corneal and conjunctival biopsy findings are presented. To our knowledge this is the first case report of a keratopathy occurring in perhexilene toxicity. After withdrawal of the drug the papilloedema and keratopathy subsided, but some visual deficit remains. The properties of perhexilene maleate and other amphiphilic drugs are described, and the possible aetiology of vortex keratopathy is discussed.

Conjunctiva↗
PubMed1984

Pseudoexfoliative disease: histochemical evidence of an affinity with zonular fibres.

The histochemical staining properties of the abnormal material deposited in the anterior segment of the eye in the pseudoexfoliation syndrome and the zonular ligaments of the lens are essentially the same. Both present the staining characteristics of oxytalan, the microfibrillar component of elastic tissue. Reasons are advanced for regarding the pseudoexfoliative material as a product of the ciliary and lenticular epithelium.

Aged↗
PubMed1984

Regulation of gastroduodenal HCO-3 transport by luminal acid in the frog in vitro.

Luminal acid (10 mM HCl) is a stimulant of surface epithelial HCO-3 transport in mammalian stomach and duodenum in vivo. To determine whether a humoral mechanism is involved in mediation of this response, amphibian fundic, antral, or proximal duodenal mucosae were mounted in parallel in an in vitro chamber with their nutrient (serosal) surfaces facing a common solution. The mucosal surfaces were bathed by separate solutions and the rate of HCO-3 transport by one mucosa titrated (at pH 7.40) during exposure of the parallel tissue to luminal acid. In studies of fundic HCO-3 transport, H+ secretion was inhibited with the histamine H2-antagonist tiotidine (10(-4) M). Fundic luminal acid stimulated HCO-3 transport by a parallel fundus (27 +/- 6%) or antrum (53 +/- 27%) but had no effect on a parallel duodenum. Antral luminal acid had no effect on a parallel antrum, indicating that the gastric stimulant is of fundic origin. Duodenal luminal acid increased HCO-3 transport by both parallel duodenum (21 +/- 5%) and fundus (109 +/- 32%). Stimulation of HCO-3 transport occurred at higher luminal pH in duodenum (approximately 4.0) than in fundus (approximately 2.0). Thus, exposure to luminal acid releases humoral factor(s) capable of stimulating surface epithelial HCO-3 transport by both stomach and duodenum. The actions of these putative stimulants are in part tissue specific, and they may be important in mediation of mucosal protection against luminal acid.

Animals↗
PubMed1984

Gastric mucosal protective mechanisms: roles of epithelial bicarbonate and mucus secretions.

Secretion of HCO3 (amounting to 2-10% of maximum H+ secretion) in conjunction with the adherent mucus gel layer (functioning as a mixing barrier) protects gastric mucosa from luminal acid by a process of surface neutralization. Gastric HCO3 secretion is augmented by cholinergic agonists, prostaglandins and low luminal pH. Ulcerogens attenuate HCO3 secretion although passive diffusion of alkali consequent upon an increase in mucosal permeability may mask these inhibitory actions. Studies in vitro indicate that HCO3 transport in the stomach is dependent on oxidative metabolism, carbonic anhydrase activity and involves a CL exchange mechanism. Mucus, synthesized and released from epithelial cells, adheres to the mucosal surface as a thin (less than 80 microns in rat) but continuous gel layer. Prostaglandins and carbachol induced release of preformed mucus and thereby increase thickness, whereas acute exposure to ulcerogens has little effect on overall dimensions of the surface mucus layer. Measurements of pH gradients adjacent to gastric mucosa indicate that the disposal of luminal H+ occurs by extracellular neutralization. However, the fall in pH at the apical cell membrane when luminal pH is low (pH 1.5) suggests that while a mucus-bicarbonate barrier comprises the first line of mucosal defence, other factors are involved in the overall process of mucosal protection in the stomach.

16,16-Dimethylprostaglandin E2↗
PubMed1984

Current concepts of gastroduodenal mucosal protection.

Mucosal protection against luminal acid and pepsin and recovery from acute damage in the upper gastrointestinal tract depends upon a number of interrelated mechanisms. The thin adherent mucus gel layer protects against shear and luminal pepsin and provides a mixing barrier for surface neutralization of H+ by HCO3- secreted from the underlying epithelia. Gastric HCO3- transport amounts to 2-10% of maximum H+ rate and involves a Cl- exchange mechanism. The rate of duodenal HCO3- transport is some 5-fold greater and both Cl- exchange and transcellular secretion of HCO3- occur. Blood flow ensures adequate oxygenation, provides a pool of HCO3- and maintains mucosal acid-base balance. Gastroduodenal mucosa has a high proliferative rate and in the stomach, the process of continual cell replacement is augmented by restitution of epithelial integrity following acute damage.

Animals↗
PubMed1984

Effect of luminal acid on gastric and duodenal bicarbonate transport.

Epithelial HCO3 transport by stomach and duodenum is influenced by luminal pH. Acid itself, but not stimulants of gastric HCl secretion, increase mucosal alkaline secretion in a variety of in vitro and in vivo systems. Using pairs of amphibian mucosa, both gastric and proximal duodenal HCO3 transport was stimulated by low luminal pH. This response displayed some tissue specificity and operates by a humoral mechanism. In the anaesthetized cat, the increase in duodenal epithelial HCO3 secretion following exposure of the lumen to acid (pH2) is probably independent of luminal Cl-. Low luminal pH in the stomach did not influence HCO3 secretion by the duodenum either in vitro or in vivo. The process of acid-stimulated epithelial HCO3 transport may be important in maintaining H+ ion disposal in the upper gastrointestinal tract in response to low luminal pH.

Animals↗
PubMed1983

The metabolism of halothane by hepatocytes: a comparison between free radical spin trapping and lipid peroxidation in relation to cell damage.

The technique of free radical spin trapping has been applied to demonstrate the formation of free radicals produced during the metabolism of halothane by rat liver hepatocytes under hypoxic conditions. The results obtained support previous findings that reported sex differences in the metabolic activation of halothane by rats in vivo. Cell viability under hypoxic conditions, as judged by trypan blue staining and lactate dehydrogenase release, shows a correlation with the extent of metabolism of halothane as measured by electron spin resonance spectroscopy. The extent of lipid peroxidation was measured by diene conjugation, malondialdehyde production and chemiluminescence. The latter technique allowed the demonstration of lipid peroxidation during incubations of hepatocytes under aerobic conditions. The magnitude of the aerobic chemiluminescence showed a similar sex dependency to the extent of free radical formation under hypoxic conditions. Cell viability measurements show that halothane metabolism in both hypoxic and aerobic conditions can lead to cell death. Consequently, oxidative lipid damage could be a cause of cell damage, as judged by cell viability, additional to covalent binding.

Animals↗
PubMed1983

Angiogenic factor in vitreous from diabetic retinopathy.

Vitreous from patients with proliferative diabetic retinopathy contains an angiogenic substance which stimulates the proliferation of blood vessels on the chick chorioallantoic membrane, whereas vitreous from non-diabetics who do not have a proliferative retinopathy does not.

Allantois↗
PubMed1983

Elastic and precursor fibres in the normal human eye.

Completely formed elastic fibres consist of a core of amorphous elastin within a mantle of microfibrils. The fibrillar component may occur as isolated bundles (oxytalan) or may be randomly intermingled with variable amounts of elastin (elaunin). The distribution of both mature elastic and incomplete oxytalan and elaunin fibres in the different parts of 53 human eyes from foetal life to old age is described, as evaluated by light microscopy of histochemical preparations. In general elastic tissue was most evident in the collagenous structures save the adult cornea in which incomplete elastic fibres occur rarely and then late in life. Precursor forms predominate in early childhood and show a limited and slow capacity for maturation. The suspensory zonular fibres of the lens appear to be composed largely of oxytalan throughout life. There is also evidence that corneal epithelium and endothelium, irideal smooth muscle and, less certainly, retinal pigment epithelium can synthesise the fibrillar component, although not elastin, of elastic tissue.

Adolescent↗