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Biomedical subjects

R Hammersley

Publications and source records attributed to R Hammersley.

At least 19 recordsLinked to original sources
PubMed2004

Mercury vapour levels in dental practices and body mercury levels of dentists and controls.

AIM: A study of 180 dentists in the West of Scotland was conducted to determine their exposure to mercury during the course of their work and the effects on their health and cognitive function. DESIGN: Data were obtained from questionnaires distributed to dentists and by visiting their surgeries to take measurements of environmental mercury. METHODS: Dentists were asked to complete a questionnaire including items on handling of amalgam, symptoms experienced, diet and possible influences on psychomotor function such as levels of stress and alcohol intake. They also completed the 12-item General Health Questionnaire. Dentists were asked to complete a dental chart of their own mouths and to give samples of urine, hair and nails for mercury analysis. The dentists were visited at their surgeries where environmental measurements were made in eight areas of the surgery and they undertook a computerised package of psychomotor tests. One hundred and eighty control subjects underwent a similar procedure, completing a questionnaire, having their amalgam surfaces counted, giving urine, hair and nail samples and undergoing the psychomotor test procedure. RESULTS: Dentists were found to have, on average, urinary mercury levels over 4 times that of control subjects although all but one dentist had urinary mercury below the Health and Safety Executive health guidance value of 20 mumol mmol(-1) creatinine. Urine was found to be a better biological marker for mercury exposure than hair or nails.Dentists were significantly more likely than control subjects to have suffered from disorders of the kidney but these symptoms were not significantly associated with their level of mercury exposure as measured in urine. One hundred and twenty two (67.8%) of the 180 surgeries visited had environmental mercury measurements in one or more areas above the Occupational Exposure Standard (OES) set by the Health and Safety Executive. In the majority of these surgeries the high levels of mercury were found at the skirting and around the base of the dental chair. In 45 surgeries (25%) the personal dosimetry measurement (ie in the breathing zone of dental staff) was above the OES. CONCLUSION: On the basis of these findings, it is recommended that greater emphasis should be made relating to safe handling of amalgam in the training and continuing professional development of dentists, that further studies are carried out on levels of mercury exposure of dental team members during the course of their working day, and that periodic health surveillance, including urinary mercury monitoring, of dental personnel should be conducted to identify possible effects of practising dentistry.

Air Pollutants, Occupational↗
PubMed2002

Health and neuropsychological functioning of dentists exposed to mercury.

OBJECTIVES: A cross sectional survey of dentists in the west of Scotland and unmatched controls was conducted to find the effect of chronic exposure to mercury on health and cognitive functioning. METHODS: 180 dentists were asked to complete a questionnaire that included items on handling of amalgam, symptoms experienced, possible influences on psychomotor function, and the 12 item general health questionnaire. Dentists were asked to complete a dental chart of their own mouths and to give samples of urine, hair, and nails for mercury analysis. Environmental measurements of mercury in dentists' surgeries were made and participants undertook a package of computerised psychomotor tests. 180 control subjects underwent a similar procedure, completing a questionnaire, having their amalgam surfaces counted, giving urine, hair, and nail samples and undergoing the psychomotor test package. RESULTS: Dentists had, on average, urinary mercury concentrations over four times that of control subjects, but all but one dentist had urinary mercury below the Health and Safety Executive health guidance value. Dentists were significantly more likely than control subjects to have had disorders of the kidney and memory disturbance. These symptoms were not significantly associated with urinary mercury concentration. Differences were found between the psychomotor performance of dentists and controls after adjusting for age and sex, but there was no significant association between changes in psychomotor response and mercury concentrations in urine, hair, or nails. CONCLUSIONS: Several differences in health and cognitive functioning between dentists and controls were found. These differences could not be directly attributed to their exposure to mercury. However, as similar health effects are known to be associated with mercury exposure, it would be appropriate to consider a system of health surveillance of dental staff with particular emphasis on symptoms associated with mercury toxicity where there is evidence of high levels of exposure to environmental mercury.

Adult↗
PubMed1999

The effects of sucrose and maize oil on subsequent food intake and mood.

The effects of sucrose and oil preloads were explicitly compared in a single-blind controlled trial using a between-subjects design. Eighty adult subjects (forty-three male, thirty-seven female) aged 18-50 years received at 11.00 hours one of four yoghurt preloads. All were 80 g low-fat, unsweetened yoghurt (188 kJ), containing additionally (1) saccharin (control, 23 kJ), or (2) 40 g sucrose (859 kJ), (3) 40 g maize oil (1569 kJ), (4) 20 g sucrose, 20 g maize oil (1213 kJ). Subjects were normal eaters and of normal weight (male mean weight: 68.8 (SD 3.2) kg, BMI 21.8 (SD 1.6) kg/m2; female mean weight: 53.7 (SD 5.1) kg, BMI 20.4 (SD 1.2) kg/m2). Food intake was measured with a food diary and mood with ten single Likert scales. ANOVA was conducted using preload type (saccharin, sucrose, oil, sucrose + oil), sex (male, female) and early v. late breakfast times as factors. Mood was analysed using the same design, with time of rating (immediate, 60 min, 120 min) as an additional factor. Men ate more after the saccharin preload than after the other preloads, but did not vary the time of their next solid food. Women increased the intermeal interval only after the oil preload, which also had the highest energy content value, but did not vary the energy content of their next solid food. The saccharin preload decreased rated tiredness at 2 h compared with the sucrose preload, possibly due to its lower energy content. The preloads containing sucrose or sucrose + oil increased calmness between 1 and 2 h afterwards, compared with the saccharin preload. It is concluded that both sucrose and oil increase the intermeal interval in men, but that women are less sensitive to preloading. The mood effects suggest that tiredness after carbohydrate at 2 h may in part be a decrease in rated energy compared with the increased rated energy found after a preload with low energy content. Carbohydrate may genuinely increase calmness. These effects apply to non-restrained eaters of normal weight.

Adolescent↗
PubMed1998

Effects of meal composition on blood alcohol level, psychomotor performance and subjective state after ingestion of alcohol.

Moderating effects of meal composition on psychomotor performance impairment and feelings after alcohol were examined in a between-subjects design. Fifty-one male volunteers fasted or received either a high carbohydrate (85% energy) or a high protein (94% energy) meal. Alcohol was administered at a dose to achieve a blood alcohol level (BAL) of 60 mg/100 ml, as a placebo. Subjects performed a dual task of primary tracking and secondary reaction time and a five-choice reaction time task. Feelings were also assessed by rating. The high carbohydrate meal reduced BAL at peak and 2 h after drinking, but a high protein meal had no significant effect. Although performance was impaired by alcohol, neither meal significantly reduced impairment and there was no effect of meal type on performance in the placebo condition. However, alcohol increased rated intoxication and the high carbohydrate meal reduced this effect. Subjects who had consumed high protein meals had more negative affect 2 h after alcohol than did subjects who had consumed high carbohydrate meals or fasted. It is concluded that there is only a weak relationship between BAL and performance impairment and food has only limited effects on impairment, although it reduces BAL.

Adolescent↗
PubMed1998

An examination of next-day hangover effects after a 100 mg/100 ml dose of alcohol in heavy social drinkers.

AIMS: Carry-over effects or the hangover hypothesis postulates that alcohol continues to impair performance the morning after drinking, even after low or moderate doses. Performance deficits have been attributed to the residual effects of recent drinking. The present study examined evidence for residual alcohol consumption on human performance when blood alcohol level has declined to zero. DESIGN: A within-subjects, repeated measures, placebo controlled experiment was conducted with double-blind alcohol administration to investigate the effects of alcohol the morning after ingestion. SETTING: All subjects were studied in Glasgow, Scotland, UK. PARTICIPANTS: Forty healthy male moderate to heavy social drinkers between 18 and 45 years of age. MEASUREMENTS: Psychomotor performance, subjective state and quality of sleep were examined under alcohol and placebo with a 1-week interval between test sessions. Enough alcohol was given to place subjects above the legal limit for driving at peak blood alcohol. FINDINGS: There was no evidence for impaired performance the morning after ingestion. Effects were found for subjective state and sleep quality. CONCLUSIONS: The findings suggest that after a 100 mg/100 ml dose of alcohol people who: (a) have no alcohol left in their blood and; (b) do not feel hung over will generally be fit to drive.

Adolescent↗
PubMed1995

Effects of carbohydrate intake on subsequent food intake and mood state.

The effects of a sucrose drink (160 kcals/40 grams of cane sugar) on mood state (Profile of Mood States) were examined over time in a between-subjects, blind placebo design. Orosensory factors were virtually eliminated due to the prior use of a benzocaine anaesthetic lozenge. The ingestion of sucrose failed to have any substantial effect on mood immediately after intake or 30 and 60 min thereafter, although two female subjects reported an increase in energy at 30 min. There was no evidence that the carbohydrate preload increased hunger or eating, rather a delay in food intake was noted subsequent to the ingestion of sugar which was not found following ingestion of saccharin or water.

Adolescent↗
PubMed1995

The effects of expectancy and alcohol on cognitive-motor performance.

Previous studies have found equivocal evidence for expectancy effects on cognitive-motor performance. The effects of expectancy and alcohol on a dual tracking and reaction-time task analogous to some driving skills, and on choice reaction-time, were studied in a balanced-placebo design (n = 90). A dose of alcohol achieving 80 mg/100 ml (high dose) had large effects on both tasks, but a low dose (40 mg/100 ml) had no significant effects. Expecting alcohol led to subjects who received the high dose performing significantly better on the primary tracking task than subjects expecting placebo (but also receiving the high alcohol dose). By contrast, on a secondary reaction-time task, subjects who had received placebo performed worse 100-130 minutes after drinking, if they had expected alcohol. All groups felt more drunk than baseline and expecting alcohol made subjects feel more able to perform, whatever drink they had received. The implications of these findings for the nature of expectancy effects on performance and the relationship between expectations and strategy are discussed.

Adolescent↗
PubMed1995

Drugs associated with drug-related deaths in Edinburgh and Glasgow, November 1990 to October 1992.

Between 1991 and 1992 there was a four-fold increase in drug-related deaths in Glasgow. Comparing records of the drug-related deaths for November 1990-October 1991 and November 1991-October 1992 in Edinburgh and Glasgow, it was found that the increase in Glasgow was statistically significant and that heroin, often mixed with other drugs, which most often included temazepam, diazepam and alcohol, was implicated in the increase in deaths in Glasgow. A number of the deceased had been prescribed temazepam or diazepam. Discussed are the hazards of drug mixing and the possibility that the use of buprenorphine by drug injectors previously had kept the number of overdoses relatively low.

Cross-Sectional Studies↗
PubMed1995

A pilot study of the effect of low level exposure to mercury on the health of dental surgeons.

OBJECTIVES: This project was conducted to examine whether the computerised analysis of psychomotor responses available from Cognitive Drug Research is appropriate for measuring an effect of low level exposure to mercury in dentists. METHODS: A computerised battery of psychomotor tests was given to two groups of dentists (older dentists and trainees) and to two age matched control groups. As well as the psychomotor tests, volunteers were required to complete a questionnaire to identify potential influences on psychomotor performance and to provide a sample for analysis of urinary mercury. RESULTS: Statistical analysis of the results showed that the older dentists had slightly higher concentrations of urinary mercury although most were around background levels and they were all within occupational limits. Five of the psychomotor tests showed no differences between the performance of the four groups. The older dentists showed significantly better performance on the simple reaction time test and significantly poorer performance in the immediate word recall and delayed word recall tests. CONCLUSIONS: Poorer performance in memory recall tests confirms previously reported studies. This together with the confirmation that this test system is a practical tool in the occupational setting suggests that a larger study of the effects of mercury exposure on dentists would be appropriate.

Adult↗
PubMed1994

The effects of sucrose on everyday eating in normal weight men and women.

Energy intake was estimated from the food diaries of 52 overnight-fasted adult volunteers after ingestion of 110 ml of a solution of either 40 g of sucrose or 4.34 g of saccharin administered in blind conditions. Men consumed more calories and carbohydrates than women. Women's eating was unaffected by the preload. The sucrose preload led to 60% of male subjects choosing to consume a calorific beverage soon afterwards; they then delayed eating compared to men who received a saccharin preload. Men who had received sucrose, but consumed no beverage, ate as early as the saccharin preload group. It is concluded that under fasted, blind administration followed by everyday eating, sucrose does not increase hunger, but eating behaviour after a preload varies with eating habits.

Adult↗
PubMed1994

A digest of memory phenomena for addiction research.

The implications for addiction research of recent knowledge about human memory are described. It is important that research using self-reported data understands the limits of such data. The nature of human memory and the selective, constructive processes of remembering provide one set of limits. Abandoning retrospective data entirely is not feasible in addiction research, for it would require the abandonment of current and prospective self-reported data as well, as they are also subject to memory biases. Because of memory distortions, self-reports, even by rigorous questionnaire, are biased narratives rather than incomplete but otherwise accurate evocations of past events. These limits necessitate caution and humility in the interpretation of findings, and cannot be eliminated by any particular set of research methods. There will never be a philosophers' stone which will convert self-reported data into absolutely accurate figures of quantity, frequency and timing. Nor is it straightforward to infer social and psychological causality from the organization and timing of events as remembered.

Bias↗
PubMed1992

Cue exposure and learning theory.

The implications are discussed for cue exposure treatment of four theoretical issues; (a) spontaneous recovery, (b) response competition, (c) generalization, and (d) the cognitive basis of conditioning. It is suggested that practical cue exposure treatment will not be as straight-forward as initial trials have suggested.

Alcoholism↗
PubMed1992

Adolescent drug use, health and personality.

Four factors have confounded the association between drug use and morbidity: (a) known drug users may be less healthy than unknown drug users; (b) drug users are rarely compared to control subjects; (c) the socio-economic status of drug users predisposes them to ill-health; (d) the personality of drug users predisposes them to ill-health. Here, controlling for these confounds, in a study of 210 adolescent drug users it was found that subjective ill-health was more strongly related to drug use than was objective ill-health. Drug use was related to neuroticism and psychopathic deviance. Controlling for personality, drug use accounted for little additional variance in health. It is concluded that drug use and health are not strongly related amongst adolescent drug users, although, because of their personalities, drug users tend not to feel well. Implications are discussed for the self-treatment explanation of drug use and for the design of preventative programmes.

Adolescent↗
PubMed1992

Alcohol placebos: you can only fool some of the people all of the time.

Some data from three studies of the acute psychological effects of alcohol are presented. After blind administration subjects could often tell that they had consumed alcohol, presumably because of its physiological effects. About 50% of subjects who received placebo alcohol felt slightly drunk and guessed that they had received alcohol. But, subjects who had actually received alcohol rated themselves as more drunk and were much more likely to guess that they had received alcohol. Subjects could also approximately estimate how much alcohol they had drunk. These findings suggest that the effects of unblinding should be considered when alcohol is administered in placebo designs. True blind placebo administration may only be possible when achieved BAL is < 40 mg/100 ml.

Alcohol Drinking↗
PubMed1992

Predicting initiation to and cessation of buprenorphine and temazepam use amongst adolescents.

Two interviews separated by 12 months (mean) were conducted with a purposive sample of Glaswegian adolescent drug misusers. Across that interval, beginning to use buprenorphine and temazepam were predictable by prior extent of other substance use, especially cannabis and tobacco, and by the Drug Misuse Scale, using selected MMPI items. About 50% of those who had been using either drug prior to first interview did not use at all between first and second interview. For temazepam, this cessation was not predictable, but ceasing to use buprenorphine was more likely the less time subjects had used this drug and if they had never injected. It is concluded that personality and frequent substance use predispose to drug misuse, but that additional factors must lead to dependence.

Adolescent↗