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Biomedical subjects

S A Edwards

Publications and source records attributed to S A Edwards.

At least 19 recordsLinked to original sources
PubMed2004

Double layers and interparticle forces in colloid science and biology: analytic results for the effect of ionic dispersion forces.

We study analytically two of the central problems of colloid science: the structure of the double layer surrounding a charged particle and the forces between two such particles. Traditionally, these have been understood using a combination of electrostatic forces acting on the ions and the entropy of the same ions. Here we derive explicit formulas showing how the often dominant dispersion forces between ions and the surfaces can dramatically change the structure of the double layer and the forces.

Colloids↗
PubMed2003

Impaction bone grafting in revision hip surgery.

We retrospectively reviewed the use of impaction bone grafting with cement for the fixation of femoral and acetabular components in revision hip arthroplasty. Seventy hips formed the basis of the study, with a mean follow-up time of 37 months. Sixty-eight percent of the femurs showed severe bone loss (Endoklinik grades 3 and 4). The mean Harris hip and Merle D'Aubigne Postel scores were 84 and 15.4, respectively. Massive subsidence occurred in only one femoral revision (>10 mm) and cup migration >5 mm in 6 cases. Loosening was seen in 1 revision for sepsis but none for aseptic loosening. Five complications were identified that were related to the surgical technique. We therefore support the use of this technique in revision surgery in patients with extensive bone loss.

Adult↗
PubMed2003

Intake of nutrients from pasture by pigs.

The domestic pig evolved from the omnivorous wild boar and has retained many natural foraging behaviour patterns. Although most modem commercial pigs are housed and fed concentrate diets, interest in the potential nutrient contribution from pasture has increased due to growth in outdoor and organic pig production systems. The energy requirements of outdoor pigs are increased by approximately 15% under Northern European conditions as a result of greater climatic energy demand and locomotory activity. The nutritional contribution made by pasture will depend on the availability, nutrient composition, grazing intake and digestive utilisation of herbage. Information on these topics is currently very sparse. Herbage availability is often low due to farm rotational policy or destructive foraging by the pigs. Herbage composition shows large varietal and seasonal differences, but the high fibre content reduces the efficiency of energy utilisation and may impair utilisation of other nutrients. Intake of grazed herbage varies widely between individuals, but is typically approximately 2.0 kg DM/d for dry sows fed restricted concentrate, and approximately 0.1 kg DM/d for growing pigs offered ad libitum concentrate. This intake can contribute 50% of the maintenance energy requirement and a high proportion of the amino acid, mineral and trace element requirements of dry sows, but < 5% of requirements of growing pigs. Whilst the potential to increase nutrient intakes from grazing exists, this process requires better understanding of herbage intake and digestion, and development of better systems for paddock management.

Animal Feed↗
PubMed2003

Effect of different nutritional regimens before ovulation on plasma concentrations of metabolic and reproductive hormones and oocyte maturation in gilts.

This study examined the effect of feeding either a maintenance (1.35 kg day(-1)) or high (3.5 kg day(-1)) plane of nutrition for 19 days after oestrus on oocyte maturity and both reproductive and metabolic hormone concentrations in gilts. Blood samples were collected each day from oestrus until slaughter on day 19 and during two pulse bleeds (15 min samples for 8 h) conducted on day 12 and day 18. After slaughter, oocytes were recovered from the presumed ovulatory population of follicles, matured in vitro for 46+/-2 h with 10% of their own follicular fluid, and then fixed and stained to determine the stage of nuclear maturation of the oocyte. Gilts fed the high diet had a higher proportion of oocytes that reached metaphase II than gilts fed the maintenance diet (88.3+/-2.71% versus 68.2+/-6.48%; P=0.013). Circulating concentrations of insulin-like growth hormone I (IGF-I) and the number of LH pulses were lower (P<0.05) in gilts fed the maintenance diet compared with gilts fed the high diet on day 12 and day 18. Mean oestradiol and progesterone concentrations were higher (P<0.05) for gilts fed the maintenance diet compared with gilts fed the high diet. Leptin concentrations were also higher on day 19 in gilts fed the high diet (2.16+/-0.26 ng ml(-1) (n=9) versus 3.20+/-0.32 (n=11), P=0.025). The results of this study indicate that improved oocyte quality (increased proportion of oocytes that reached metaphase II) is associated with a number of changes in reproductive and metabolic hormones. Further studies are required to indicate which hormonal mechanism may, in turn, lead to increased embryo survival and eventual litter size.

Animal Nutritional Physiological Phenomena↗
PubMed2002

Analysis of polyethylene thickness of tibial components in total knee replacement.

BACKGROUND: Excessive wear of the polyethylene bearing surfaces of tibial components has become an important factor in early failure of total knee arthroplasty. Inadequate thickness of the polyethylene insert is one cause of excessive wear, and various minimum thicknesses have been recommended in order to reduce contact stresses within the polyethylene. However, the true thicknesses of modular polyethylene tibial inserts typically are not stated accurately by the manufacturers in their product information. The purpose of this study was to determine whether the information about the thickness of tibial inserts supplied by the manufacturers is adequate. METHODS: Five of the thinnest available polyethylene tibial inserts from five different manufacturers were selected. The minimum thickness of each was measured with use of a Sigma electronic micrometer comparator to an accuracy of +/-0.005 mm. RESULTS: The stated thicknesses of the polyethylene tibial inserts were 8, 9, and 10 mm, values that differed markedly from the actual minimum thicknesses, which ranged from 5.5722 to 6.2048 mm (mean values). CONCLUSION: The thickness of polyethylene tibial inserts has been implicated as a potential cause of excessive wear and early failure of total knee replacements. This paper highlights the fact that the information supplied by the manufacturers is inaccurate and potentially misleading; in one case, the true thickness was much less than the recommended minimum thickness. We recommend that the minimum thickness of the tibial components as well as the combined thickness of the polyethylene insert and the metal tibial tray be specified in the product information and on the packaged insert.

Arthroplasty, Replacement, Knee↗
PubMed2001

The treatment of impending and existing pathological femoral fractures using the long gamma nail.

The subtrochanteric region of the femur accounts for one-third of all pathological fractures requiring surgical intervention. The large forces occurring in this region and the possible non-occurrence of bony consolidation constitute a difficult problem to the trauma surgeon. The medical records and X-rays of 25 consecutive patients treated with the long gamma nail (LGN) for pathological (impending or existing) fractures of the femur were analysed retrospectively. Our results in the use of the LGN for pathological fractures of the femur have been good. We recommend an aggressive approach to the early stabilisation of impending fractures and the use of distal locking.

Aged↗
PubMed2001

Feeding tuna oil to the sow at different times during pregnancy has different effects on piglet long-chain polyunsaturated fatty acid composition at birth and subsequent growth.

In an attempt to prevent decreases in piglet 20 : 4n-6 status at birth while increasing 22 : 6n-3 status, multiparous sows (eight per treatment) were allocated to one of three different treatments: a basal diet fed from day 63 of pregnancy to term; basal diet supplemented with tuna oil (17.5 g/kg) from day 63 to day 91 and then basal diet alone from day 92 to term; basal diet alone from day 63 to day 91 and then basal diet supplemented with tuna oil from day 92 to term. Tuna oil supplementation increased mainly 22 : 6n-3 intake. Supplementation with tuna oil between day 92 and term increased 22 : 6n-3 to a greater extent in all piglet tissues (brain, liver, retina and the remaining carcass) at birth than supplementation with tuna oil between days 63 and 91. However, while piglet 20 : 4n-6 decreased to a greater extent in liver and carcass when diets were supplemented with tuna oil between days 92 and term than between days 63 and 91, in the brain and retina, the reverse was true; 20 : 4n-6 was decreased to a greater extent between days 63 and 91 than between 92 and term. The effect of pregnancy nutrition on the growth of piglets until 7 d postweaning (35 d of age) was assessed after removing any residual effects of pregnancy treatment by cross-fostering some piglets at birth. Piglets, the diets of whose dams had been supplemented with tuna oil during pregnancy, grew faster during the first 35 d of life than the progeny of sows fed only the basal diet. Feeding tuna oil to sows at different times during pregnancy therefore did not prevent decreases in piglet 20 : 4n-6 status at birth, but did suggest that changes in piglet brain 20 : 4n-6 status between days 63 and 91 of pregnancy were not reversible by later nutrition. Supplementing the diet of the pregnant sow with tuna oil had beneficial effects on postnatal piglet growth.

Animal Nutritional Physiological Phenomena↗
PubMed2001

The influence of gestation feeding strategy on body composition of gilts at farrowing and response to dietary protein in a modified lactation.

Previous experiments have indicated that reproductive function in lean, modern genotypes may be more dependent on body protein mass than, as previously believed, on body lipid reserves. This was investigated in a 3 x 2 factorial arrangement of treatments, involving 60 first-parity sows, comparing three pregnancy feeding strategies and two lactation diets. During pregnancy, sows were fed either a basal diet (5 g lysine/kg, 13 MJ of DE/kg [C]) or the same quantity of basal diet + energy source [E], or additional basal diet supplying both protein and energy [A]. The level of supplement for E and A was adjusted weekly to achieve a backfat thickness measurement (P2 position) of 28 mm at farrowing. Isoenergetic lactation diets were fed to appetite and provided either high (180 g CP/kg, 9 g lysine/kg [H]) or low lysine (120 g CP/kg, 6 g lysine/kg [L]). From d 21 of lactation, sows were separated from their litters and housed next to a boar for 8 h each day; final weaning occurred on d 31. Pregnancy treatment differences in backfat and weight were achieved, with C sows having less backfat on d 1 of lactation than E and A sows (E = 28.1, A = 28.0, C = 22.7 kg, P < 0.001). Sows fed additional basal diet were heavier than E sows, which were heavier than C sows (E = 190, A = 201, C = 178 kg, P < 0.001). Average feed intake over lactation showed a pregnancy feeding effect, with E sows eating less than A or C sows (E = 4.9, A = 5.2, C = 5.4 kg/d, P < 0.005). Total lactation weight loss was affected by pregnancy feeding (E = 18.0, A = 19.0, C = 8.4 kg, P < 0.05) and by lactation diet (L = 19.0, H = 11.3 kg, P < 0.05), whereas total lactation backfat loss was affected only by pregnancy treatment (E = 6.9, A = 6.5, C = 4.6 mm, P < 0.05). No pregnancy treatment or lactation diet effects were observed for litter performance. Lactation diet affected weaning-to-estrus interval, with more sows on the H diet coming into estrus within 6 d of partial weaning (P < 0.05), but there was no pregnancy treatment effect. Therefore, voluntary feed intake during lactation was suppressed by increased fat reserves at a limited body protein mass but not when body protein mass was also increased. Partial weaning-to-estrus interval was increased by reduced dietary protein.

Animals↗
PubMed2000

The long gamma nail: a DGH experience.

Subtrochanteric fractures constitute a difficult problem for the trauma surgeon. The long Gamma nail (LGN) represents an efficient technique in the management of these fractures. A retrospective analysis of 51 LGN with an average follow up of 16 weeks is presented. The average age of the patients was 72 years and the mean time to union was 11 weeks. The incidence of peroperative, early local and late local complications was 8, 8 and 4%, respectively or 20% in total. The thirty-day mortality was 8%. Our results in the use of the LGN have been good. Its introduction provides the trauma surgeon with a tool for allowing earlier mobilisation, decreasing operative time, surgical trauma, blood loss and wound problems. The LGN is a device by which most complex fractures in the proximal femur can be managed with a single implant.

Adult↗
PubMed2000

Efficacy of forearm versus upper arm tourniquet for local anaesthetic surgery of the hand.

A prospective study was undertaken to compare the use of forearm and upper arm tourniquets for local anaesthetic procedures on the hand. One hundred consecutive patients with an upper arm tourniquet were compared with a further consecutive 100 patients in whom a forearm tourniquet was used. The tourniquet time was always less than 20 minutes and the scoring of perceived pain was not significantly different in the two groups. Use of a forearm tourniquet was well tolerated and was not associated with an increase in complications.

Adult↗
PubMed1999

Relationships between fatty acid status of sow plasma and that of umbilical cord, plasma and tissues of newborn piglets when sows were fed on diets containing tuna oil or soyabean oil in late pregnancy.

To investigate the relationships between maternal, umbilical cord and piglet fatty acid status, multiparous sows (six per diet) were fed on diets containing supplements (30 g/kg) of either soyabean oil or tuna oil for the last 21 d of pregnancy. The proportions of most fatty acids differed between diets: in particular, the tuna-oil-containing diet supplied more 22:6n-3 and less 18:2n-6 fatty acids than the soyabean-oil-containing diet. Maternal plasma fatty acid concentrations (mg/l) were greater than those in umbilical plasma and 20:4n-6 and 22:6n-3 fatty acids were present in higher proportions (g/100 g fatty acids) in umbilical than maternal plasma. Feeding tuna oil increased the proportionate amounts (g/100 g fatty acids) of total n-3 fatty acids (particularly 22:6n-3) in umbilical cord, plasma and piglet tissues compared with feeding soyabean oil: in contrast, the proportion of 20:4n-6 was decreased by feeding tuna oil. Changes in piglet fatty acid proportions as a result of oil feeding were not influenced by piglet weight. While proportions of the long-chain n-3 and n-6 polyunsaturated fatty acids in piglet liver, spleen and reproductive tract (ovaries plus uterus of the female, testes of the male) correlated well with those of umbilical plasma, those in brain and retina were poorly correlated. Therefore umbilical plasma cannot be used to predict the fatty acid status of piglet brain.

Animal Nutritional Physiological Phenomena↗
PubMed1998

Effect of feeding tuna oil or soyabean oil as supplements to sows in late pregnancy on piglet tissue composition and viability.

To investigate whether long-chain n-3 polyunsaturated fatty acids could cross the porcine placenta in late pregnancy and alter neonatal piglet tissue composition, multiparous sows (seven per diet) were fed on diets containing a supplement (30 g/kg) of either soyabean oil or tuna oil for the last 21 d of pregnancy and the first 7 d of lactation. The proportions of all fatty acids, except 18:1n-7, differed between diets: in particular, the tuna-oil-containing diet supplied more 22:6n-3 and less 18:2n-6 fatty acids than the soyabean-oil-containing diet. The proportions of n-3 fatty acids, particularly 22:6n-3 (g/100 g total fatty acids) in sow plasma, colostrum and milk were increased and the proportion of 18:2n-6 was decreased by feeding tuna oil. Piglet tissue n-3 fatty acid proportions (particularly 22:6n-3), obtained shortly after birth, were increased in piglets born to tuna-oil-fed sows compared with progeny of soyabean-oil-fed sows. The increase in the proportion of n-3 fatty acids (g/100 g total fatty acids) in piglet tissues as a result of tuna-oil feeding, compared with soyabean-oil-feeding, was in the order plasma > liver > erythrocytes > spleen > brain > retina. Piglets born to tuna-oil-fed sows had a lower viability score at birth than the progeny of soyabean-oil-fed sows. The proportions of long-chain n-3 fatty acid in tissues of new-born piglets were increased by feeding tuna oil to the sow in late pregnancy; however no improvements in piglet viability were observed.

Animal Feed↗
PubMed1995

Postoperative vaginal cuff irradiation using high dose rate remote afterloading: a phase II clinical protocol.

PURPOSE: In September 1989, a postoperative Phase II high dose rate (HDR) brachytherapy protocol was started for International Federation of Gynecology and Obstetrics (FIGO) Stage I endometrial adenocarcinoma. This review reports the overall survival, local control, and complication rates for the initial 63 patients treated in this Phase II study. METHODS AND MATERIALS: High dose rate brachytherapy was delivered using an Iridium-192 HDR remote afterloader. Sixty-three patients were entered into the Phase II protocol, each receiving two vaginal cuff treatments 1 week apart (range 4-12 days) with vaginal ovoids (diameter 2.0-3.0 cm). No patient received adjuvant external beam radiation. A dose of 32.4 Gy in two fractions was prescribed to the ovoid surface in 63 patients. The first three patients treated at our institution received 15, 16.2, and 29 Gy, respectively, to determine acute effects. RESULTS: At a median follow-up of 1.6 years (range 0.75-4.3 years) no patient has developed a vaginal cuff recurrence. One regional recurrence (1.6%) occurred at 1.2 years at the pelvic side wall. This patient is alive and without evidence of disease 7 months after completion of salvage irradiation, which resulted in the only vaginal stenosis (1.6%). Fourteen patients (22%) experienced vaginal apex fibrosis by physical exam, which was clinically symptomatic in four patients. Two patients reported stress incontinence; however, these symptoms were noted prior to their HDR therapy. One patient died 2.4 years after HDR therapy due to cardiovascular disease without evidence of cancer at autopsy. CONCLUSION: Preliminary results of our phase II HDR vaginal cuff protocol for postoperative FIGO Stage IA, Grade 3 or Stage IB, Grade 1-2 patients demonstrate that 32.4 Gy in two fractions is well tolerated by the vaginal cuff mucosa. Local control appears comparable to our prior experience and others with low dose rate (LDR) brachytherapy. Additional patient accrual and further follow-up will better determine the late morbidity, local control, and overall survival of these patients.

Adult↗
PubMed1995

Controlled exposures of young asthmatics to mixed oxidant gases and acid aerosol.

To help assess short-term respiratory responses to summertime air pollution, we exposed 24 asthmatic volunteers aged 11-18 in a chamber to respirable acid aerosol (mass median aerodynamic diameter 0.66 micron) plus 0.3 ppm nitrogen dioxide (NO2) plus 0.2 ppm ozone (O3). The aerosol contained available hydrogen ions (H-) at an average concentration of 2.6 mumol/m-, equivalent to 127 micrograms/m3 sulfuric acid (H2SO4); some H+ probably was in NH4HSO4 rather than H2SO4. The volunteers were exposed separately to O3/NO2 without acid and to clean air. Exposures lasted 90 min, including three 15-min exercise sessions with ventilation averaging 32 L/min, at 21 degrees C and 50% relative humidity. Asthma medications were withheld before and during exposures. Subjects gargled lemonade to minimize acid neutralization by oral ammonia (NH3). Exercise-induced bronchospasm was evident in all exposures. Differences in group mean lung function response among H2SO4/O3/NO2, O3/NO2, and clean-air exposures were not statistically significant. Individuals' measured oral NH3 concentrations or estimated inhaled doses of H2SO4 did not significantly predict their lung function changes. A few subjects showed unfavorable function changes during pollutant exposures, which might be chance occurrences or might indicate the existence of an acid-pollution-susceptible subgroup among young asthmatic subjects.

Adolescent↗
PubMed1994

An analysis of the causes of piglet mortality in a breeding herd kept outdoors.

The 229 piglets which died on an outdoor unit during a period of eight months were examined post mortem to determine the cause of death. The majority of the deaths (72 per cent) had occurred by the time that the litter was first inspected and of these 27 per cent had uninflated lungs and 53 per cent of the piglets born alive had no food in the stomach. Seventeen per cent of the stillborn pigs were of type I and 83 per cent were of type II. It was impossible to identify stillborn piglets reliably from their external appearance alone. At all ages, crushing was the most common cause of death (72 per cent of liveborn piglets). Six per cent of the corpses of the piglets had been damaged by birds, and attacks on live piglets occurred in the later stages of the study.

Animal Husbandry↗
PubMed1993

Anaesthesia for gynaecological laparoscopy--a comparison between the laryngeal mask airway and tracheal intubation.

In a single-blind, randomised, controlled study, we compared two anaesthetic techniques in 60 patients undergoing gynaecological laparoscopy. In the first group, ventilation was controlled, after paralysis and tracheal intubation. In the second group, a laryngeal mask airway was inserted and spontaneous or assisted ventilation allowed. There were no clinically significant differences in the intra-operative conditions of the two groups, although the procedure was quicker in the second group. The only significant difference in morbidity was a greater incidence of nausea and vomiting in the second group in the first 4 h after operation. We conclude that use of the laryngeal mask airway is an acceptable technique for elective gynaecological laparoscopy, in patients who are at low risk of regurgitation.

Adolescent↗