Plant glutathione S-transferases: enzymes with multiple functions in sickness and in health

Glutathione S-transferases (GSTs) are abundant proteins encoded by a highly divergent, ancient gene family. Soluble GSTs form dimers, each subunit of which contains active sites that bind glutathione and hydrophobic ligands. Plant GSTs attach glutathione to electrophilic xenobiotics, which tags them for vacuolar sequestration. The role of GSTs in metabolism is unclear, although their complex regulation by environmental stimuli implies that they have important protective functions. Recent studies show that GSTs catalyse glutathione-depend-ent isomerizations and the reduction of toxic organic hydroperoxides. GSTs might also have non-catalytic roles as carriers for phytochemicals.

Sex-specific effects of pain-related anxiety on adjustment to chronic pain

OBJECTIVE

Considerable research indicates that both high levels of anxiety and female sex are associated with increased sensitivity to experimental pain and greater experience of clinical pain. In general, however, previous research has not investigated the joint effects of sex and anxiety on pain responses. A single previous laboratory-based study indicated that anxiety was inversely related to pain thresholds among men but not among women. The present study examined the relation between pain-related anxiety and adjustment to chronic pain in a sex-dependent manner.

DESIGN AND SETTING

A total of 215 (114 women, 101 men) chronic pain patients referred to a multidisciplinary treatment center completed questionnaires assessing anxiety and adjustment to chronic pain.

RESULTS

Results generally supported the previous laboratory-based finding indicating that an inverse relation between anxiety and adjustment to chronic pain was present only among male patients. Although male patients with high pain-related anxiety reported greater pain severity, greater interference of pain, and lower levels of daily activity than male patients with low anxiety, this effect was not present among female patients. Moreover, the effects of pain-related anxiety on adjustment to chronic pain were not attributable to either hypervigilance or use of passive coping strategies. Potential explanations and implications for the present findings are discussed.

Cloning and characterization of glyoxalase I from soybean

Glyoxalase I and glutathione transferase (GST) are two glutathione-dependent enzymes which are enhanced in plants during cell division and in response to diverse stress treatments. In soybean, a further connection between these two enzymes has been suggested by a clone (Accession No. X68819) resembling a GST being described as a glyoxalase I. To characterize glyoxalase I in soybean, GmGlyox I resembling the dimeric enzyme from animals has been cloned from a cDNA library prepared from soybean suspension cultures. When expressed in Escherichia coli, GmGlyox I was found to be a 38-kDa dimer composed of 21-kDa subunits and unlike the enzyme from mammals showed activity in the absence of metal ions. GmGlyox I was active toward the hemithioacetal adducts formed by reacting methylglyoxal, or phenylglyoxal, with glutathione, homoglutathione, or gamma-glutamylcysteine, showing no preference for homoglutathione adducts over glutathione adducts, even though homoglutathione is the dominant thiol in soybean. When the clone X68819 was expressed in E. coli, the respective recombinant enzyme was active as a GST rather than a glyoxalase and was termed GmGST 3. GmGST 3 was active as a homodimer (45 kDa) composed of 26-kDa subunits and showed a preference for glutathione over homoglutathione when conjugating 1-chloro-2,4-dinitrobenzene. Both enzymes are associated with cell division in soybean cultures, but GmGST 3 (0.4% total protein) was 40 times more abundant than GmGlyox I (0.01%).

Hypertension prevalence and care in an urban and rural area of Tanzania

OBJECTIVE

To describe the prevalence, detection, treatment and control of hypertension in an urban and rural area of Tanzania.

DESIGN

Two linked cross-sectional population-based surveys.

SETTING

A middle-income urban district of Dar es Salaam (Ilala) and a village in the relatively prosperous rural area of Kilimanjaro (Shari).

PARTICIPANTS

Seven hundred and seventy adults (> 15 years) in Ilala and 928 adults in Shari were studied.

RESULTS

Hypertension prevalence (blood pressure > or = 140 and/or 90 mmHg, or known hypertensives receiving anti-hypertensive treatment) was 30% (95% confidence interval, 25.1-34.9%) in men and 28.6% (24.3-32.9%) in women in Ilala, and 32.2% (27.7-36.7%) in men and 31.5% (27.8-35.2%) in women in Shari. Age-standardized hypertension (to the New World Population) prevalence was 37.3% (32.2-42.5%) among men and 39.1% (34.2-44.0%) in women in Ilala, and 26.3% (22.4-30.4%) in men and 27.4% (24A-30.4%) in women in Shari. In both areas, just under 20% of hypertensive subjects were aware of their diagnosis, approximately 10% reported receiving treatment and less than 1% were controlled (blood pressure < 140/90 mmHg). Hypertensive subjects were older, had greater body mass indices and waist: hip ratios, and had more risk factors for hypertension and its complications (smoking, heavy alcohol consumption, physical inactivity, obesity and diabetes) than non-hypertensives.

CONCLUSIONS

There is a high prevalence of hypertension in rural and urban areas of Tanzania, with low levels of detection, treatment and control. This demonstrates the need for cost-effective strategies for primary prevention, detection and treatment of hypertension and the growing public health challenge of non-communicable diseases in Sub-Saharan Africa.

A controlled trial of substrate-enhanced, warm reperfusion ("hot shot") versus simple reperfusion

BACKGROUND

Modified reperfusion after aortic cross-clamping is claimed to reduce myocardial injury, thus improving postoperative myocardial performance.

METHODS

We measured perioperative release of creatine kinase-MB and troponin-T in 40 patients undergoing valve replacement (combined with coronary grafts in 12 cases) to determine whether infusion of a modified reperfusate before cross-clamp removal reduced myocardial injury. Patients were randomly allocated to one of two groups with minimization for age, surgeon, operation, and ventricular function. The control group received unmodified reperfusion, while the study group received a normothermic reperfusate, enhanced with glutamate and aspartate, for 5 minutes before removal of the cross-clamp. Serial determinations of troponin-T, creatine kinase-MB isoforms, and total creatine kinase-MB activity were made up to 5 days postoperatively. Requirements for inotropic support and evidence of myocardial infarction were documented.

RESULTS

Creatine kinase-MB activity, creatine kinase-MB isoforms, and troponin-T were not significantly different between the two groups. There were no differences in the incidence of postoperative myocardial infarction or in inotrope requirement.

CONCLUSIONS

Our study did not demonstrate any advantage in using modified reperfusion in this group of patients.

Using time domain characteristics to discriminate physiologic and parkinsonian tremors

Tremor amplitude and frequency do not always clearly differentiate subjects with particular pathologies from control subjects or from subjects with other pathologies, especially in early stages of a disease. For patients with early stages of Parkinson's disease (PD) the discriminative power of amplitude was compared with that of other time domain characteristics of tremor recordings that are probably not evident clinically. Postural tremor with and without visual feedback and rest tremor were recorded in both hands of a group of patients with Parkinson's disease (n = 21) and a group of healthy control subjects (n = 30) using displacement lasers. Velocity and acceleration data were derived from displacement data. Twelve time domain characteristics were calculated on each recording and the discriminating power of each was evaluated using the worse hand in each case. Postural tremor with no visual feedback separates the two groups of subjects most efficiently, especially in velocity and acceleration. Tremor in Parkinson's disease (in comparison to normal physiologic tremor) has a specific morphology, has a distinctive histogram, is more periodic, and contains indications of nonlinearity in the underlying dynamics. There may also be greater difference in amplitude between the two hands and time asymmetry in tremor of patients with PD. A series of finger flexions seems to enhance normal tremor but not tremor in PD and may thus aid in discrimination. Discrimination of tremor attributable to PD from normal physiologic tremor can be enhanced by measuring time domain characteristics subtler than amplitude, particularly when amplitude itself is not large. Tremor measurement should not be limited to acceleration data because some information is more visible in other variables.

Nonmetallic fixation in elective maxillofacial surgery

Resorbable fixation technology offers several benefits, including easily cut and shaped plates, strong and predictable resorption qualities, and improved patient acceptance and expectations. Moreover, resorbable fixation implants can be completely reabsorbed into the body, eliminating the need for subsequent removal. This article describes the use of this innovative technology in orthognathic surgery, including preoperative and postoperative patient needs, intraoperative patient care, and potential complications.

Indicators that count! Measuring population health at the community level

We begin with a discussion of some vitally important conceptual and methodological issues. These issues concern our understanding of community, of health, of population health and its determinants, of the concept of 'measurement' and the values that underlie it, and our reasons for wishing to measure these constructs. We then present a framework for indicator categories, propose some criteria for indicator selection and suggest an initial set of core indicators. This indicator set reflects not simply health status--no matter how broadly defined--but also the environmental, social and economic determinants of health and the "healthfulness" of the community itself. Our most important conclusion is that if the information that is contained in the data of the indicator set is to be transformed into knowledge that can empower and emancipate the community, it has to be developed in consultation with the local community and local users of the information.

The measurement of tremor using a velocity transducer: comparison to simultaneous recordings using transducers of displacement, acceleration and muscle activity

Precise kinematic measurements of tremor have historically been obtained using accelerometers. However, current technology permits precise measurements in velocity and displacement. The primary advantage of velocity recording is that only one step of integration or differentiation is required for either displacement or acceleration. A method is presented of measuring finger tremor using a laser system that transduces velocity precisely. Measurements of postural finger tremor thus obtained were compared to those simultaneously obtained from a laser system that transduces displacement, from an accelerometer and from surface electromyography (EMG) of the extensor digitorum communis. A range of amplitude and frequency content was obtained by testing control subjects and subjects with Parkinson's disease. The velocity transducer showed excellent correspondence of amplitude and frequency measurement with the displacement transducer. Measures of absolute and relative amplitude correlated well (r > or = 0.96 in amplitude measures in displacement, velocity and acceleration), and high coherence was found throughout the frequency range of interest. Measurements by the accelerometer generally showed poorer correspondence with those of the other instruments. EMG measurements showed good correspondence in some trials but poorer correspondence in others, attributed to the low level of muscle activity required in the task. Precise kinematic measurements appear to be highly sensitive to neuromotor impairment.

Associations between perfectionism, mood, and fatigue in chronic fatigue syndrome: a pilot study

This study investigated possible associations between perfectionistic personality traits, mood, and fatigue in chronic fatigue syndrome (CFS). Forty CFS sufferers referred to tertiary care and 31 control healthy subjects completed the Multidimensional Perfectionism Scale (MPS), Chalder Fatigue Questionnaire, and Hospital Anxiety and Depression (HAD) scale. Total perfectionism scores did not correlate with fatigue, anxiety, or depression in either group. Other-oriented MPS scores were significantly lower among CFS sufferers (p = .0019), especially women, and correlated negatively with physical fatigue levels overall (R = -0.27, p = .02). Total and socially prescribed MPS scores correlated with age for the CFS group alone (p = .05). Possible reasons why this study did not confirm a positive association between perfectionism and CFS are discussed. The finding that CFS sufferers set lower standards and have lower expectations for significant others may have implications for rehabilitation and recovery from this disorder.

Using frequency domain characteristics to discriminate physiologic and parkinsonian tremors

The manner in which characteristics of time series in the frequency domain can enhance discrimination between physiologic and parkinsonian tremor when tremor amplitude is low was examined. Rest tremor and postural tremor with and without visual feedback were recorded twice in the two hands of a group of patients with Parkinson's disease (PD) (n = 21) and a group of healthy control subjects (n = 30) using displacement laser systems. Recordings were analyzed quantitatively using amplitude and seven frequency domain characteristics. Postural tremor with no visual feedback allowed the most efficient discrimination between the two groups of subjects especially in velocity and acceleration (derived from displacement) and allowed identification of more patients with PD as separate from the range observed in the control group. Moreover, the frequency domain characteristics that were investigated identified the majority of the patients even when amplitude did not. After eliminating redundant (correlated) characteristics, it was found that the frequency composition of tremor in PD can be described adequately with four characteristics, which are the most reliable, independent, and discriminative elements for detecting early or subtle modifications in tremor. Also, a series of finger flexions was found to enhance physiologic tremor but not tremor in PD. Discrimination of low-amplitude tremor in PD from normal physiologic tremor is enhanced by examining the median frequency of oscillations, the concentration of power in the power spectrum, and the distribution of power in particular ranges. Tremor measurement should not be limited to acceleration data as some information is more visible in velocity time series.

Individuals from North America, Australasia, and Africa are infected with four different genotypes of human herpesvirus 8

To study human herpesvirus 8 (HHV-8) transmission between individuals and in populations, we developed a system for genetic fingerprinting of HHV-8 strains based on variation in the HHV-8 K1, glycoprotein B (gB), and glycoprotein H (gH) genes. Using this system, we sequenced nearly the entire K1 gene (840 bp); two segments of the gB gene (open reading frame 8), totaling 813 bp; and a 702-bp segment of the gH gene (open reading frame 22) from blood and tissue samples obtained from 40 human immunodeficiency virus-infected and noninfected individuals, including those with Kaposi's sarcoma, primary effusion lymphoma, or Castleman's disease. The specimen collection was assembled from individuals living in diverse geographical locations, including the United States, Australia, New Zealand, Uganda, and Zambia. As reported by others, K1 was the most variable gene, with up to 16% variation at the nucleotide sequence level and up to 32% variation at the amino acid sequence level. Despite this extensive sequence variation, the K1 amino acid sequence contained 14 conserved cysteine sites, suggesting a conserved tertiary structure. gB and gH sequences were highly conserved, in most cases differing by <0.6% in pairwise comparisons. K1 was the most useful gene for strain discrimination, but the other genes enabled the discrimination of strains with identical K1 sequences. Individuals from diverse geographic locations were infected with four different HHV-8 genotypes; strains did not strictly segregate by continent of origin. The majority of HHV-8 strains from the United States and Europe were relatively closely related, whereas some strains identified from Uganda and Australia were phylogenetically distant. Genotype I strains were the most common and were found on three continents. Identical sequences were found in specimens obtained from different body sites and at different times from the same individual.

Moclobemide in the treatment of major depressive disorder (DSM-3) following traumatic brain injury

Major depression (MDD) following traumatic brain injury (TBI) is a common phenomenon. There are no adequate studies in the literature defining optimum treatments for this condition following TBI. The opportunity arose to analyse a group of patients who were included in a larger study of an antidepressant (moclobemide). As the treatment, but not the delivery, was known, this has the status of an open study. Twenty-six patients with major depression of late onset (mean 4.67 years post-TBI) were identified (18 male, 8 female), with a mean age at injury 28.49 years. The group was moderately depressed with Hamilton Depression score (HAM-D) of 23.385 and moderately anxious with Hamilton Anxiety score (HAM-A) of 21.231. Mean HAM-D reduction was 81% and HAM-A reduction 81%. Of the 26 subjects 23 were defined as responders. Onset of action was rapid, with 17 responding by day 3. Irritability scores showed a mean reduction of 57% and pain scores a reduction of 39%. It is concluded that moclobemide may be an effective treatment for MDD following TBI, but properly controlled studies must be carried out to confirm this.

Thyroid nodules, thyroid function and dietary iodine in the Marshall islands

BACKGROUND

Thyroid nodules have been found to be common in the population of the Marshall Islands. This has been attributed to potential exposure of radioiodines from the nuclear weapons tests on Bikini and Eniwetok between 1946 and 1958.

METHODS

In order to get a full picture of thyroid pathology in the Marshallese population potentially exposed to radioactive fallout we performed a large thyroid screening programme using palpation, high resolution ultrasound and fine needle biopsies of palpable nodules. In addition, various parameters of thyroid function (free T3, free T4, thyroid stimulating hormone [TSH]) and anti-thyroid antibodies were examined in large proportions of the total population at risk. Since dietary iodine deficiency is an established risk factor for thyroid nodules, iodine concentration in urine samples of 362 adults and 119 children was measured as well as the iodine content of selected staple food products.

RESULTS

The expected high prevalence of thyroid nodules was confirmed. There was no indication of an increased rate of impaired thyroid function in the Marshallese population. A moderate degree of iodine deficiency was found which may be responsible for some of the increased prevalence of thyroid nodules in the Marshallese population.

CONCLUSIONS

Studies on the relationship between exposure to radioiodines and thyroid nodules need to take dietary iodine deficiency into account in the interpretation of findings.

Dimerisation of maize glutathione transferases in recombinant bacteria

Two cDNAs encoding novel type III maize (Zea mays) GST subunits, ZmGST VI and ZmGST VII, have been cloned in addition to the previously described ZmGST V. Together with the type I GSTs ZmGST I and ZmGST III, these subunits were expressed in Escherichia coli, both individually and in tandem combinations using a customised pET vector. The GST dimers formed were then characterised. When type I GSTs were co-expressed only the respective homodimers were formed rather than the ZmGST I-III heterodimer. The failure to form this heterodimer, together with the negligible herbicide-detoxifying activity associated with recombinant ZmGST III-III, suggests that the identity of herbicide-detoxifying isoenzymes described in maize as being composed of ZmGST III subunits requires re-evaluation. In contrast, co-expression of the type III GSTs ZmGST V and ZmGST VI resulted in the formation of ZmGST V-V, ZmGST VI-VI and ZmGST V-VI dimers in the ratio 1:1:2 as predicted for random subunit association. ZmGST V-VI had kinetic characteristics intermediate between those of the two homodimers, indicating that the subunits were catalytically independent of one another. Co-expression of ZmGST V and ZmGST VII resulted in the formation of ZmGST V-VII and this isoenzyme was subsequently identified in maize plants. Attempts to dimerise type I GST subunits with type III GST subunits proved unsuccessful. These results demonstrate the utility of co-expressing recombinant GSTs to explore the potential of subunit-subunit associations and to help unravel the complexity of homodimeric and heterodimeric GSTs in plants.

An action plan for tobacco control at regional level

Smoking is the single biggest preventable cause of death in the UK; killing over 120 000 people each year, contributing to inequalities in health, exacerbating and causing poverty. Smoking has increased steadily among children since 1988 and more recently, among young adults. The current context in the UK is highly favourable for introducing comprehensive tobacco control measures. This paper summarises a regional action plan for tobacco control. Actions at district and regional levels are outlined to establish a comprehensive local tobacco control framework and complement national tobacco control measures. Measures include: a 'SWOT' analysis of current activity; systematic monitoring of smoking prevalence, attitudes to smoking, and the impact of tobacco control interventions; provision of effective smoking cessation support to a minimum standard throughout the health service; increased coverage of smoke-free public places and workplaces; enforcement of legislation on illegal sales to children and against smuggling and selling illegally imported tobacco; paid and unpaid mass media campaigns; and systematic lobbying for fiscal and legislative measures. One of the key components of the plan is the introduction of evidence-based tobacco control strategies at district levels. These should include a performance framework with clear organisational and managerial accountability and employ a co-ordinated, multiagency, partnership approach. Priority groups should be identified. Strategies should seek to engage the public to build support for tobacco control measures. Sufficient time, staff, resources and training must be allocated to tobacco control work and progress towards objectives monitored.

Donepezil overdose: a tenfold dosing error

OBJECTIVE

To report toxicity resulting from donepezil administration following a tenfold dosing error.

CASE SUMMARY

A 79-year-old white nursing home patient with a history of Alzheimer disease and hypertension was inadvertently given 50 mg of donepezil instead of her usual 5-mg dose. She presented to the emergency department with nausea, vomiting, and persistent bradycardia (HR in the 40s). Routine laboratory studies were all within normal limits. Basilar rales were noted five hours after arrival. She was treated with atropine 0.2 mg as needed for bradycardia (HR <50 beats/min); a total of 3.0 mg was administered over 18 hours. Each bolus kept her HR >60 beats/min for one-half to two hours. No further vomiting or evidence of pulmonary edema occurred after her initial episodes. She returned to baseline by day 2 (HR in the 70s) and was returned to the nursing home.

DISCUSSION

Donepezil is a centrally acting, reversible cholinesterase inhibitor that is used in the treatment of Alzheimer disease. Donepezil is highly specific for neural acetylcholinesterases, preferentially binding acetylcholinesterase by greater than three orders of magnitude over butyrylcholinesterases. This specificity minimizes peripheral adverse effects at therapeutic doses. Our patient mainly experienced bradycardia and had minimal secretory effects compared with what is usually seen with nonspecific cholinesterase inhibition. Medication errors like the one that produced this overdose are a common but preventable cause of morbidity in healthcare facilities.

CONCLUSIONS

A tenfold dosing error caused donepezil toxicity. The main effect of this overdose was bradycardia, which responded to atropine therapy.

Indexes for identification of abnormal tremor using computer tremor evaluation systems

We consider methods of formulating indexes to identify abnormalities in tremor appropriate for computerized tremor analysis systems. Characterization of amplitude, frequency, and "harmonicity" are considered as well as how to combine several such characteristics into a single index to discriminate normal from abnormal tremor effectively. The methodological issues discussed here should be of interest to researchers and clinicians working with tremor in general and to both users and developers of computer tremor analysis systems.

Teaching public health to medical students in the United Kingdom--are the General Medical Council's recommendations being implemented?

BACKGROUND

Despite frequent calls to improve undergraduate medical public health teaching, little is known about whether curricula have changed. We report a survey of undergraduate public health teaching in UK medical schools in 1996. The survey aimed to assess whether the General Medical Council's 1993 recommendations to strengthen undergraduate medical education in public health have been implemented.

METHODS

We asked heads of academic departments of public health at all 26 UK medical schools to complete a questionnaire and provide supporting documentation for each undergraduate public health course or module. We compared results from the 1996 survey with those from a similar survey in 1992.

RESULTS

Twenty-one out of 26 (81 per cent) medical schools responded. All responding medical schools included public health teaching within their curriculum. The median number of public health courses per medical school was unchanged since 1992. A wide variety of topics were taught. Core public health subjects were taught at most schools, though over a quarter of medical schools did not cover some core topics. Between 1992 and 1996 the proportion of time devoted to teaching by lectures decreased, whereas the following all increased: teaching by small group methods; the proportion of courses using methods of assessment encouraging active learning; and the contribution of public health courses to the final degree assessment.

CONCLUSION

The findings suggest that many of the General Medical Council's recommendations for improving the delivery of undergraduate education are being addressed by public health teaching in UK medical schools. However, addressing the gaps in undergraduate public health teaching revealed in this survey is a continuing challenge for academic public health departments. Medical schools should review the content of their undergraduate public health teaching to ensure that tomorrow's doctors are adequately equipped with public health knowledge and skills.