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Biomedical subjects

S M Hampton

Publications and source records attributed to S M Hampton.

At least 19 recordsLinked to original sources
PubMed2005

Effect of menopause on melatonin and alertness rhythms investigated in constant routine conditions.

Although studies have reported the effects of the menstrual cycle on melatonin rhythmicity, none has investigated the effects of menopause on the melatonin rhythm. The circadian rhythm in melatonin and its relationship to subjective alertness was investigated in pre- and postmenopausal women under constant routine conditions (controlled posture, dim lighting, calorie intake, temperature, and prolonged wakefulness). Eleven healthy pre-menopausal (42+/-4 yr) and 10 postmenopausal women (55+/-2 yr) participated in the study. Salivary melatonin samples and subjective measures of alertness and sleepiness were assessed hourly during the 22 h constant routine protocol. Postmenopausal women had a significantly earlier melatonin acrophase (1.1+/-0.5 h clock time in decimal h; mean+/-SEM, p<0.05) compared to the pre-menopausal women (2.3+/-0.3 h). There was no significant difference between melatonin onset and amplitude between the pre-menopausal and postmenopausal women. Self-rated alertness declined in both study groups as the length of sleep deprivation increased. Melatonin onset preceded the onset of self-rated sleepiness in both groups. The time interval between melatonin onset and the onset of sleepiness and alertness offset was significantly greater in the postmenopausal women compared to the pre-menopausal women. In conclusion, under controlled experimental conditions the timing of the melatonin rhythm was advanced in postmenopausal women altering its phase relationship to subjective alertness and sleepiness.

Adult↗
PubMed2004

Postprandial metabolic profiles following meals and snacks eaten during simulated night and day shift work.

Shift workers are known to have an increased risk of developing cardiovascular disease (CVD) compared with day workers. An important factor contributing to this increased risk could be the increased incidence of postprandial metabolic risk factors for CVD among shift workers, as a consequence of the maladaptation of endogenous circadian rhythms to abrupt changes in shift times. We have previously shown that both simulated and real shift workers showed relatively impaired glucose and lipid tolerance if a single test meal was consumed between 00:00-02:00 h (night shift) compared with 12:00-14:00 h (day shift). The objective of the present study was to extend these observations to compare the cumulative metabolic effect of consecutive snacks/meals, as might normally be consumed throughout a period of night or day shift work. In a randomized crossover study, eight healthy nonobese men (20-33 yrs, BMI 20-25kg/m2) consumed a combination of two meals and a snack on two occasions following a standardized prestudy meal, simulating night and day shift working (total energy 2500 kcal: 40% fat, 50% carbohydrate, 10% protein). Meals were consumed at 01:00/ 13:00 h and 07:00/19:00h, and the snack at 04:00/16:00 h. Blood was taken after an overnight fast, and for 8 h following the first meal on each occasion, for the measurement of glucose, insulin, triacylglycerol (TAG), and nonesterified fatty acids (NEFA). RM-ANOVA (factors time and shift) showed a significant effect of shift for plasma TAG, with higher levels on simulated night compared to day shift (p < 0.05). There was a trend toward an effect of shift for plasma glucose, with higher plasma glucose at night (p = 0.08), and there was a time-shift interaction for plasma insulin levels (p < 0.01). NEFA levels were unaffected by shift. Inspection of the area under the plasma response curve (AUC) following each meal and snack revealed that the differences in lipid tolerance occurred throughout the study, with greatest differences occurring following the mid-shift snack. In contrast, glucose tolerance was relatively impaired following the first night-time meal, with no differences observed following the second meal. Plasma insulin levels were significantly lower following the first meal (p < 0.05), but significantly higher following the second meal (p < 0.01) on the simulated night shift. These findings confirm our previous observations of raised postprandial TAG and glucose at night, and show that sequential meal ingestion has a more pronounced effect on subsequent lipid than carbohydrate tolerance.

Adult↗
PubMed2002

Factors affecting the introduction of complementary foods in the preterm infant.

OBJECTIVES: The aim of the study was to identify current infant feeding practices among carers of preterm infants. DESIGN: Structured interviews on milk and complementary feeding practices were conducted with mothers of preterm infants at intervals until infants were 12 months corrected age. SETTING: Recruitment took place in three local Surrey hospitals over a 2 y period. SUBJECTS: Two-hundred and fifty-three preterm infants (139 male, 114 female) including 33 sets of twins and three sets of triplets were recruited. RESULTS: Forty-nine percent of the preterm infant group received first solid foods (the commencement of 'weaning') before the current Department of Health (DoH) guideline. The mean+/-s.e.m. weaning age from birth was 17.1+/-0.23 weeks. Ninety-five percent of the infants were weaned before the DoH guideline when the data was examined from term (mean 11.5+/-s.e.m. 0.21 weeks). Twenty-one percent were weaned before the DoH guideline for preterm infants which is that 'the infant weighs at least 5 kg' (mean 5.61+/-s.e.m. 0.01 kg). Human milk-fed infants were significantly lighter at weaning than combined milk-fed infants (5.32+/-0.12 vs 5.72+/-0.01 kg; P<0.05) even though they were weaned at a similar age. Infant formula-fed infants (mean weaning age from term 10.2+/-0.47 weeks) were weaned significantly earlier than both human milk-fed (11.9+/-0.49 weeks; P<0.05) and combined milk-fed (11.9+/-0.25 weeks; P<0.005) infants. CONCLUSIONS: The introduction of complementary foods varied widely between carers of preterm infants and compliance with DoH guidelines was poor. Further studies on preterm infants are necessary to see if weaning practices affect long-term growth and morbidity and to provide a basis for the development of appropriate recommendations. SPONSORSHIP: This work was funded by the MAFF Food Intolerance Programme.

Age Factors↗
PubMed2001

Postprandial triacylglycerol responses in simulated night and day shift: gender differences.

A number of reports suggest that shift workers have an increased risk of coronary heart disease (CHD). One contributing factor may be the consumption of meals at night with consequent altered postprandial responses. This study investigated circulating triacylglycerol (TAG), a possible risk factor for CHD, after meals during a simulated day and night shift. Twenty-five healthy participants (10 women and 15 men) were studied. They were given a pre-meal at 0800 h and a test meal at 1330 h on a simulated day shift and then an identical pre-meal at 2000 h and test meal at 0130 h, respectively, on a simulated night shift with maintained wakefulness. Blood was sampled for 9 h after the test meal for analysis of basal and postprandial plasma TAG levels. ANOVA for repeated measures indicated higher TAG in men compared with women (p < 0.0001) and higher responses at night in both genders (p = 0.027). Incremental area under the curve (IAUC) analysis indicated that men had significantly increased postprandial TAG levels at night compared with the day: (IAUC 0-540 min, mean +/- SEM) 253.29 +/- 28.73 versus 148.33 +/- 17.28 mmol/L x min, respectively, p = 0.025. In women, night and day responses (61.16 +/- 8.93 versus 34.09 +/- 7.87 mmol/L x min, respectively, p = 0.457) were not significantly different. Circulating TAG remained elevated for longer at night in the men compared with the women (p = 0.009). This study demonstrates the existence of gender and time-of-day differences in TAG responses to a meal. These raised TAG levels at night, for a prolonged time in men, may be relevant to the increased risk of CHD in shift workers.

Adult↗
PubMed2001

Postprandial hormone and metabolic responses amongst shift workers in Antarctica.

The circadian rhythms of many night-shift workers are maladapted to their imposed behavioural schedule, and this factor may be implicated in the increased occurrence of cardiovascular disease (CVD) reported in shift workers. One way in which CVD risk could be mediated is through inappropriate hormonal and metabolic responses to meals. This study investigated the responses to standard meals at different circadian times in a group of night-shift workers on a British Antarctic Survey station at Halley Bay (75 degrees S) in Antarctica. Twelve healthy subjects (ten men and two women) were recruited. Their postprandial hormone and metabolic responses to an identical mixed test meal of 3330 kJ were measured on three occasions: (i) during daytime on a normal working day, (ii) during night-time at the beginning of a period of night-shift work, and (iii) during the daytime on return from night working to daytime working. Venous blood was taken for 9 h after the meal for the measurement of glucose, insulin, triacylglycerol (TAG) and non-esterified fatty acids. Urine was collected 4-hourly (longer during sleep) on each test day for assessment of the circadian phase via 6-sulphatoxymelatonin (aMT6s) assay. During normal daytime working, aMT6s acrophase was delayed (7.7+/-1.0 h (s.e.m.)) compared with that previously found in temperate zones in a comparable age-group. During the night shift a further delay was evident (11.8+/-1.9 h) and subjects' acrophases remained delayed 2 days after return to daytime working (12.4+/-1.8 h). Integrated postprandial glucose, insulin and TAG responses were significantly elevated during the night shift compared with normal daytime working. Two days after their return to daytime working, subjects' postprandial glucose and insulin responses had returned to pre-shift levels; however, integrated TAG levels remained significantly elevated. These results are very similar to those previously found in simulated night-shift conditions; it is the first time such changes have been reported in real shift workers in field conditions. They provide evidence that the abnormal metabolic responses to meals taken at night during unadapted night shifts are due, at least in part, to a relative insulin resistance, which could contribute to the documented cardiovascular morbidity associated with shift work. When applied to the 20% of the UK workforce currently employed on shift work, these findings have major significance from an occupational health perspective.

Adult↗
PubMed2000

Evaluating the role of magnetic resonance imaging scans in the surgical management of acoustic neuromas.

OBJECTIVE: To assess the reliability of magnetic resonance imaging (MRI) in predicting the size and position of an acoustic neuroma, with particular reference to the intracanalicular portion. STUDY DESIGN: Prospective study comparing the position of the tumor in the internal auditory canal on fast spin-echo MRI with the actual position measured intraoperatively. METHODS: The study was performed in a tertiary referral neurotology center, encompassing both the public and private health care systems. Fifteen consecutive patients admitted for acoustic neuroma removal via the translabyrinthine approach were studied. The main outcome measure was tumor position in the internal auditory canal expressed in millimeters, accurate to the nearest 0.5 mm. RESULTS: The fast spin-echo MRI was accurate within an error of 1 mm in predicting the lateral extent of the tumor in the internal auditory canal. CONCLUSION: Fast spin-echo MRI can accurately predict the lateral extent of an acoustic neuroma and allow accurate planning of the surgical approach.

Adult↗
PubMed2000

Belfast Cochlear Implant Centre; the surgical results of the first 100 implants.

We assess the surgical results of the first one hundred cochlear implant operations at the Belfast Cochlear Implant Centre. This paper is in the form of a retrospective case series, taking into account the surgical technique used and any problems encountered. Initially 28 operations were performed using the standard inverted U-shaped incision. After Gibson and Harrison described a vertical postaural incision we began using a slight modification of this technique for any further implantations. Since November 1994 the vertical post aural skin incision has been used in 71 patients. The surgical complications of cochlear implantation include haematoma, wound infection and flap necrosis of varying degrees of severity. We report a low level of these complications, particularly with the vertical incision.

Adolescent↗
PubMed2000

Evidence for altered control of glucose disposal after total colectomy.

Colonic fermentation of organic matter to short-chain fatty acids has been implicated in the improvement in insulin sensitivity achieved by feeding diets rich in complex carbohydrates. The present study assessed the potential role of the colon in determining postprandial glucose kinetics. Metabolic responses to a complex-carbohydrate test meal were determined in conjunction with a primed continuous infusion of D-[6,6-2H]glucose in a group of ileostomists and sex-matched controls. Glucose disposal (GD) was computed using Steele's (1959) non-steady-state kinetics on a single compartment model. Insulin sensitivity was derived using cumulative GD as the dependent variable, and time and the integrated insulin concentration as independent variables. The ileostomist group had a significantly higher postprandial plasma insulin concentration ( P = 0.034) compared with the control group, but no difference in the plasma glucose concentration. Total GD was similar in each group, although the insulin-dependent GD was substantially lower in the ileostomists (0.46 v. 0.13 mg glucose/min per pmol, P = 0.015). The ileostomist group also showed a 50% lower rate of glucose oxidation in the postprandial period (p = 0.005), although the rate of non-oxidative GD was not significantly affected. The present study indicates that loss of the colon is associated with several characteristics of the insulin resistance syndrome, and favours a view that the colon has a role in the control of postprandial glucose.

Adult↗
PubMed1999

Prematurity, immune function and infant feeding practices.

Recently, there has been much interest in the literature in the role of early nutrition and the health of the individual in adulthood. A majority of infants in the UK are born full term, while preterm infants account for 4-6% of the total births. Milk feeding practices are divided into three groups: breast, combination (breast-fed with formula as 'top-up') and bottle (formula). In studies conducted by our group and other researchers immune function in full-term and preterm infants has been assessed by monitoring total and specific immunoglobulin E and specific immunoglobulin G levels. Dietary modification by the pregnant mother with a history of allergy in the family has been shown to have a positive effect with respect to allergy outcome and prevention of atopic disease in the infant. However, this dietary modification has to occur before week 22 of pregnancy and continue until the end of lactation to achieve a beneficial outcome to the infant. The stress of mothers restricting their diets may be disadvantageous to the fetus, and therefore any gain due to the dietary restriction may be lost. Researchers have shown that the early introduction of complementary foods and the greater diversity of these foods appeared to result in an increase in the incidence of atopic disease in the infant. In conclusion, in order to reduce the risk in their babies, mothers with a family history of atopic disease should breast-feed for more than 15 weeks and introduce solid foods after 4 months, limiting the variety until at least 6 months.

Aging↗
PubMed1999

The influence of the colon on postprandial glucagon-like peptide 1 (7-36) amide concentration in man.

Glucagon-like peptide (7-36) amide (GLP-1) is an incretin hormone of the enteroinsular axis released rapidly after meals despite the fact that GLP-1 secreting cells (L-cells) occur predominantly in the distal gut. The importance of these colonic L-cells for postprandial GLP-1 was determined in healthy control subjects and in ileostomy patients with minimal small bowel resection (<5 cm). Subjects were fed a high complex carbohydrate test meal (15.3 g starch) followed by two carbohydrate-free, high fat test meals (25 g and 48.7 g fat respectively). Circulating levels of glucose, insulin, glucagon, glucose insulinotrophic peptide (GIP) and GLP-1 were measured over a 9-h postprandial period. For both subject groups the complex carbohydrate test meal failed to elicit a rise in either GIP or GLP-1. However, both hormones were elevated after the fat load although the GLP-1 concentration was significantly reduced in the ileostomist group when compared with controls (P=0.02). Associated with this reduction in circulating GLP-1 was an elevation in glucagon concentration (P=0.012) and a secondary rise in the plasma glucose concentration (P=0.006). These results suggest that the loss of colonic endocrine tissue is an important determinant in the postprandial GLP-1 concentration. Ileostomists should not be assumed to have normal enteroinsular function as the colon appears to have an important role in postprandial metabolism.

Analysis of Variance↗
PubMed1998

Altered postprandial hormone and metabolic responses in a simulated shift work environment.

The circadian rhythms of most night shift workers do not adapt fully to the imposed behavioural schedule, and this factor is considered to be responsible for many of the reported health problems. One way in which such disturbances might be mediated is through inappropriate hormonal and metabolic responses to meals, on the night shift. Twelve healthy subjects (four males and eight females) were studied on three occasions at the same clock time (1330 h), but at different body clock times, after consuming test meals, first in their normal environment, secondly after a forced 9 h phase advance (body clock time approximately 2230 h) and then again 2 days later in the normal environment. They were given a low-fat pre-meal at 0800 h, then a test meal at 1330 h with blood sampling for the following 9 h. Parameters measured included plasma glucose, non-esterified fatty acids (NEFAs), triacylglycerol (TAG), insulin, C-peptide, proinsulin and glucose-dependent insulinotropic polypeptide, and urinary 6-sulphatoxymelatonin. In contrast with a previous study with a high-fat pre-meal, postprandial glucose and insulin responses were not affected by the phase shift. However, basal plasma NEFAs were lower immediately after the phase shift (P < 0.05). Incremental (difference from basal) TAG responses were significantly higher (P < 0.05) immediately after the phase shift compared with before. Two-day post-phase shift responses showed partial reversion to baseline values. This study suggests that it takes at least 2 days to adapt to eating meals on a simulated night shift, and that the nutritional content of the pre-meals consumed can have a marked effect on postprandial responses during a simulated phase shift. Such findings may provide a partial explanation for the increased occurrence of cardiovascular disease reported in shift workers.

Adult↗
PubMed1997

Cochlear implant extrusion in a child with keratitis, ichthyosis and deafness syndrome.

We present a child with keratitis, ichthyosis and deafness (KID) syndrome implanted with a Nucleus device. We discuss the would complications of this child and the steps taken to deal with the problems encountered when the wound failed to heal, followed by the partial extrusion of her implant. Early surgical management involved resuturing the wound but when this failed a rotational flap was required to cover the implant package and allow eventual healing. Despite the wound problems and revision surgery she has a good audiological result.

Child↗
PubMed1997

Subcutaneous emphysema as a complication of tonsillectomy.

Subcutaneous emphysema occurs when air is introduced into the tissues. This can happen as a complication during, or immediately after surgery. It has rarely been described after tonsillectomy. Definitive treatment will depend on the cause. We report two cases of subcutaneous emphysema following tonsillectomy.

Adolescent↗
PubMed1996

Perforation rates after ventilation tube insertion: does the positioning of the tube matter?

A prospective study was performed of children undergoing bilateral ventilation tube insertion. One hundred and twenty-one children aged between 9 months and 10 years 3 months were admitted for surgery for secretory otitis media (glue ear). Each child had a ventilation tube inserted anteriorly in the tympanic membrane of one ear and posteriorly in the tympanic membrane of the other. They underwent regular clinical and audiological assessment until extrusion of the ventilation tubes occurred. Perforations were noted in 2.75% of tympanic membranes (4.6% of the children). The rate with posteriorly placed ventilation tubes was higher than with the anteriorly placed ventilation tubes (3.7% compared with 1.8%) though this is not statistically significant.

Child↗
PubMed1996

Postprandial hormone and metabolic responses in simulated shift work.

This study was designed to investigate postprandial responses to a mixed meal in simulated shift work conditions. Nine normal healthy subjects (six males and three females) were studied on two occasions at the same clock time (1330 h) after consuming test meals, first in their normal environment and secondly after a 9 h phase advance (body clock time 2230 h). Plasma glucose, insulin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), triacylglycerol (TAG) and non-esterified fatty acids (NEFAs) were determined at intervals for 6 h after each test meal. Postprandial plasma glucose, insulin, GIP and GLP-1 profiles were evaluated by calculating areas under the curve (AUC) for the first 2 h and the last 4 h of the sampling together with total AUC. Significantly higher postprandial glucose responses (total AUC) were observed after the phase shift than before (AUC 0-360 min, 2.01 (1.51-2.19) vs 1.79 (1.56-2.04) mmol/l.min; P < 0.02; mean (range)). No significant difference was observed when the first 2 h of each response was compared, but significantly higher glucose levels were observed in the last 4 h of the study after the phase shift than before (AUC 120-360 min, 1.32 (1.08-1.42) vs 1.16 (1.00-1.28) mmol/l.min; P < 0.05). Similar results were obtained for insulin (AUC 0-360 min, 81.72 (30.75-124.97) vs 58.98 (28.03-92.57) pmol/l.min; P < 0.01; AUC 120-360 min, 40.73 (16.20-65.25) vs 25.71 (14.25-37.33) pmol/l.min; P < 0.02). No differences were observed in postprandial plasma GIP and GLP-1 responses before and after the phase shift. Postprandial circulating lipid levels were affected by phase shifting. Peak plasma TAG levels occurred 5 h postprandially before the phase shift. Postprandial rises in plasma TAG were significantly delayed after the phase shift and TAG levels continued to rise throughout the study. Plasma postprandial NEFA levels fell during the first 3 h both before and after the phase shift. Their rate of return to basal levels was significantly delayed after the phase shift compared with before. This study demonstrates that a simulated phase shift can significantly alter pancreatic B-cell responses and postprandial glucose and lipid metabolism.

Adult↗