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Biomedical subjects

E Masterson

Publications and source records attributed to E Masterson.

34 records · Page 2Linked to original sources
PubMed1981

Pigment epithelial cells in culture. Metabolic pathways required for phagocytosis.

The phagocytosis of bovine rod outer segments as measured by the uptake of 3H-labeled outer segments was studied in a culture system. Phagocytosis was markedly inhibited by the lack of glucose and by two inhibitors of the tricarboxylic acid cycle-cytochrome system, dinitrophenol and malonate. Lactate production was increased in phagocytizing cells, but the hexose monophosphate shunt was not stimulated. The data support the conclusion that the tricarboxylic acid cycle and its associated cytochrome system play an important role as an energy source for phagocytosis in these cells. Compromise of this energy source rapidly leads to a suppression of the phagocytic process.

Animals↗
PubMed1980

Retinal pigment epithelial cell differentiation in vitro. Influence of culture medium.

Cultured chick pigment epithelial (PE) cells from stages 29 to 31 chick embryos grown in normal Eagle's minimum essential medium (MEM) exhibit marked colonial organization and differentiation. Individual cells appear epithelial and heavily pigmented. In contrast, cells grown in Ham's modified F-12 medium appear fibrocytic with colonial disorganization and little visible pigmentation. Biochemically, cells grown in F-12 medium lack receptors for both 3H-retinol and 3H-retinoic acid, although cells grown in MEM exhibit specific 3H-retinol binding. Pathways of glucose utilization differ significantly in cells grown in the two media, with considerably lower overall respiratory activity and lower pentose phosphate pathway activity seen with the F-12 medium. Thus different nutritional states can markedly affect PE cell characteristics in culture and possibly in vivo as well.

Animals↗
PubMed1978

The pentose phosphate pathway in developing chick cornea.

Embryonic chick corneas at different stages of development were evaluated for activity of the pentose phosphate pathway. The appearance of activity was concurrent with the onset of corneal transperancy (stage 40). Highest values were found after complete transparency is achieved (stage 45 and after hatching). Phenazine methosulfate, an artificial electron acceptor, increased activity at all stages studied even before endogenous activity was measurable; however, no increase in glucose uptake was observed. Thus, the enzymes for the pathway are present at early stages (i.e., stage 38 and 40) although in latent form. The pathway probably functions in the developing cornea to generate NADPH rather than sugar moieties for macromolecular incorporation.

Age Factors↗
PubMed1978

Glucose oxidation in the chick cornea: effect of diamide on the pentose shunt.

Chick embryo corneas (stages 38 and 45) have been used to study variations in pentose shunt activity following the use of a glutathione-specific oxidizing agent, diamide, and a sulfydryl blocking agent, N-ethylmaleimide (NEM). Shunt activity was measured by the ratio of radiolabeled carbon 1 (14C-1) of glucose to radiolabeled carbon 6 (14C-6) of glucose derived as expired 14CO2. Diamide and NEM were both found to increase pentose shunt activity relative to glycolysis, although by different means. Diamide appeared to exert its effect by oxidizing glutathione and creating a demand for higher shunt activity to facilitate glutathione reduction by NADPH. Both C-1 and C-6 oxidation were increased, but C-1 oxidation was increased to a much greater extent. In contrast, NEM decreased both C-1 and C-6 oxidation, with C-6 preferentially affected. Thus NEM appears to preferentially inhibit the enzymatic machinery of the glycolytic-tricarboxylic acid cycle pathway and acts as an effective metabolic stress on the cornea. Our data suggest that the pentose shunt in the cornea may serve as an important alternative pathway under conditions of metabolic stress for glucose utilization and the production of energy (ATP) in the corneal cells.

Animals↗
PubMed1977

Oxygen consumption in the developing chick cornea.

Embryonic chick corneas at different stages of development were evaluated for O2 consumption. Some embryos were treated with thyroxine or thiouracil. In untreated animals, corneal QO2 (oxygen consumption/hr./mg. dry weight) decreased from 3.60 at stage 38 to 1.58 after hatching. The temperature coefficient Q10 increased from 1.55 at stage 40 to 2.03 after hatching. If O2 consumption is calculated as microliters of O2 consumed per hour per corneal pair, it increases between stage 38 (3.20) and hatched chicks (6.20) with a plateau between stages 40 and 45. Thiouracil treatment reduced O2 consumption by the cornea at stages 42 and 45, and thyroxine treatment elevated it at stage 40.

Age Factors↗
PubMed1977

The role of thyroid hormone in the development of the chick corneal endothelium and epithelium.

Previous studies have established that thyroxine or thiouracil treatments affect the development of corneal transparency in the chick. The effects of these drugs on chick corneal epithelial and endothelial development were investigated because in the adult the integrity of these cell layers is necessary for the maintenance of corneal transparency. Chick embryos were treated with thiouracil or thyroxine at stage 36 or 38; the corneas were excised 2 to 12 days after treatment (between stages 38 and 45), and prepared for electron microscopy. The colloidal tracer ruthenium red was added during fixation to study epithelial and endothelial permeability and to stain the intercellular endothelial spaces. At all stages studied, the epithelium was impermeable to ruthenium red and this property was not affected by drug treatment. The epithelial barrier to this tracer is located in the outermost cell layer. The ease of penetration of ruthenium red through the endothelial intercellular spaces indicated the lack of zonular tight functions and the presence of gap functions in this cell layer. Thiouracil treatment delayed the development of the corneal epithelium so that at stage 45 it resembled epithelium from a normal embryo 3 stages younger. In normal animals, chick corneal endothelial development is characterized by an increasing degree of interdigitation of the lateral plasma membranes of adjacent endothelial cells with advancing embryonic age. Thiouracil treatment delayed this progressive development of adjacent cell membrane interdigitation. In contrast, thyroxine treatment accelerated the development of the lateral borders of the endothelial cells. It also appears that thyroid hormone can affect the development of the cell membranes of apposed cells in epithelium as well as the endothelium of the embryonic chick cornea.

Animals↗
PubMedDate not supplied

Need-based waiting lists for hip and knee arthroplasty.

BACKGROUND: Need-based waiting lists have been shown to offer advantages over traditional time-based waiting lists. This study investigated the effect of their introduction in our orthopaedic practice. METHODS: Each patient on the waiting list for total hip replacement (n = 240) and total knee replacement (n = 98) was invited to attend a dedicated assessment clinic. At the clinic each patient had a joint score (Harris Hip Score or American Knee Society Score) calculated. Patients with the lowest joint scores were moved to the top of the waiting lists. Scores were repeated postoperatively. RESULTS: Validation of the hip replacement and knee replacement waiting lists reduced them by 20% and 11% respectively. The efficiency and transparency of the service were increased. CONCLUSION: Need-based waiting lists are easily introduced and offer significant advantages over time-based waiting lists. We advocate their introduction in other centres.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

Relating undergraduate musculoskeletal medicine curricula to the needs of modern practice.

BACKGROUND: International studies have demonstrated significant discrepancies between undergraduate musculoskeletal curricula and the needs of modern medical practice. AIMS: To determine the prevalence of musculoskeletal disorders in primary care, General Practitioners, assessment of their undergraduate musculoskeletal training and that considered ideal for several clinical skills, and the relative importance of the ability to recognise selected clinical presentations. METHODS: A postal survey of 200 General Practitioners using a detailed questionnaire. RESULTS: The response rate was 50.5%, with respondents being an average 18.5 years in practice. They saw a mean 140.3 patients/week (range 10-270) of which 17.4% presented with musculoskeletal complaints (range 5-50%). Respondents felt their musculoskeletal education was poor, with a significant difference between it and their ideal (p = 0.007). The most important skill for a graduating doctor was history taking, examination and appropriate investigation of a musculoskeletal problem. The most important clinical presentation was recognition of traumatic quadriplegia. CONCLUSIONS: A large proportion of primary care in Ireland is devoted to musculoskeletal complaints, however, there are deficiencies perceived in undergraduate musculoskeletal education. A review of undergraduate musculoskeletal curricula, emphasising the clinically relevant aspects of this discipline is needed.

Clinical Competence↗
PubMedDate not supplied

Distal forearm fractures in children: the role of hand dominance.

A survey of 426 children with unilateral distal forearm fractures was performed to examine the role of hand dominance. Results showed a significant preponderance of fractures occurring in the non-dominant arm (p < .01). This finding has implications for possible preventive strategies in these common injuries.

Child↗