A novel educational tool for teaching ocular ultrasound

Ocular ultrasound is now in increasing demand in routine ophthalmic clinical practice not only because it is noninvasive but also because of ever-advancing technology providing higher resolution imaging. It is however a difficult branch of ophthalmic investigations to grasp, as it requires a high skill level to interface with the technology and provide accurate interpretation of images for ophthalmic diagnosis and management. It is even more labor intensive to teach ocular ultrasound to another fellow clinician. One of the fundamental skills that proved difficult to learn and teach is the need for the examiner to “mentally convert” 2-dimensional B-scan images into 3-dimensional (3D) interpretations. An additional challenge is the requirement to carry out this task in real time. We have developed a novel approach to teach ocular ultrasound by using a novel 3D ocular model. A 3D virtual model is built using widely available, open source, software. The model is then used to generate movie clips simulating different movements and orientations of the scanner head. Using Blender, Quicktime motion clips are choreographed and collated into interactive quizzes and other pertinent pedagogical media. The process involves scripting motion vectors, rotation, and tracking of both the virtual stereo camera and the model. The resulting sequence is then rendered for twinned right- and left-eye views. Finally, the twinned views are synchronized and combined in a format compatible with the stereo projection apparatus. This new model will help the student with spatial awareness and allow for assimilation of this awareness into clinical practice. It will also help with grasping the nomenclature used in ocular ultrasound as well as helping with localization of lesions and obtaining the best possible images for echographic diagnosis, accurate measurements, and reporting.

A phase II trial of neoadjuvant ABI-007, carboplatin, and gemcitabine (ACG) in patients with locally advanced carcinoma of the bladder

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Background: Neoadjuvant cisplatin-based chemotherapy benefits patients with bladder cancer, particularly in the 30% with pathologic complete response (pCR) at cystectomy. Many patients with bladder cancer are not candidates for cisplatin. Taxane-based regimens have activity in urothelial cancer. ABI-007 is an albumin-bound paclitaxel with increased activity and decreased toxicity compared to standard paclitaxel preparations.

Methods: Eligible pts have T2-4,N0,M0 or Tany,N1- 3,M0 bladder cancer with ECOG PS 0-1, and adequate marrow (granulocyte count > 1,500/mm3, platelet > 100,000/mm3, and hemoglobin > 9.0 g/dl), hepatic (transaminases < 2.5 X upper limit of normal, alkaline phosphatase < 2.5 X upper limit of normal, and bilirubin < 1.5 mg/dl) and renal function (serum creatinine < 2.0 mg/dl and/or creatinine clearance > 40 ml/min). Pts are treated with intravenous ABI-007 260 mg/m2 and carboplatin (target area under the curve=5) on day 1 with gemcitabine 800 mg/m2 on days 1 and 8, followed by radical cystectomy after three cycles of therapy. The primary study endpoint is the proportion of patients with pCR at cystectomy.

Results: 27 patients have been enrolled. By clinical staging, 20 had T2 disease, 5 had T3, 2 had T4, and 2 had nodal enlargement. All are evaluable for toxicity with 22 evaluable for response (exclusions-3 for change in dose schedule, 1 each for refusal of cystectomy and withdrawal from study). 25/27 patients received all three cycles (78 total cycles) with doses reduced in 26 cycles for toxicity. All patients had transient grade 3-4 neutropenia and 17 received filgrastim, but only two had febrile neutropenia. Six pts had pCR with an additional 5 having residual carcinoma in situ (CIS) and 1 with T1 disease at cystectomy. 54% of evaluable patients had no muscle invasive disease at cystectomy.

Conclusions: Neoajuvant ACG is active in bladder cancer with pCR rate nearing 30% and nearly as many patients with CIS but no residual invasive disease. Marrow toxicity is significant but manageable.

[Table: see text]

Optimisation of storage conditions for maintaining culturability of penicillin-susceptible and penicillin-resistant isolates of Streptococcus pneumoniae in transport medium

Methods employed by the World Health Organization (WHO) are used during this study to determine the optimum storage conditions for maintaining the culturability of Streptococcus pneumoniae in skimmed milk, tryptone, glucose and glycerin (STGG) transport medium. A comparison of S. pneumoniae strains sensitive and resistant to penicillin showed no significant difference in their survival ability in STGG medium. Furthermore, it is confirmed that storage at -70 degrees C remains most effective for maintaining viability by culture of S. pneumoniae. Storage at -20 degrees C would only be acceptable in the short-term, while storage at +4 degrees C is not recommended. Of note, this study has shown STGG medium at room temperature to be an efficient growth medium for pneumococci in the short-term. This work will help to establish robust sampling protocols when performing community studies to ensure culturability of comparison between community and laboratory pneumococci survival.

Design of an Actuated Volume Compensating SLS Prosthetic Socket

Studies have shown residual limb volume can vary −11% to 7% in a single day due to changing activity level or weight. However, volume changes of only 3% to 5% can cause users to have difficulty putting on their prosthetic socket. Many existing volume compensation methods are cumbersome, rely on the amputee to maintain the appropriate pressure level, or allow only for a decrease in limb volume. Automatic compensation for volume gain and loss is therefore needed; however, the complexity of designing such sockets renders a traditional fabrication methods cost prohibitive or technically infeasible. Selective Laser Sintering (SLS), a rapid manufacturing (RM) technology, addresses both of these concerns. SLS is a layer-based RM technology that relies on a high power laser to fuse powder particles into a solid object. Minute detail, directly from a 3D CAD model, is possible and a technique has been established for manufacturing prosthetic sockets with passive compliant regions using SLS. Based on this SLS RM technique, steps toward developing a transtibial Nylon prosthetic socket that automatically adapts to volumetric changes in a residual limb will be described. A design methodology was developed to use RM including concept generation, refinement, and final verification. In concept generation, analogies, such as “Chinese Fingertraps” and balloons, were coupled with a review of socket designs in literature and industry and interviews with prosthetists. Inflation of a bladder integrated into the wall of a SLS socket is one of the promising design concepts generated, but the concept needs further refinement. In order to confidently design an inflatable SLS prosthetic, it is critical to understand the relationship between applied pressure and deflection. A testing specimen—5.08 cm diameter thinwalled membrane—was designed to simulate a bladder integrated into the wall of a SLS socket. Several thicknesses were also used to investigate the effects of this parameter on inflation. Preliminary tests were conducted using compressed air for quantifying pressure vs. displacement. During the tests, leakage through open porosity (due to low density) was detected. Density is strongly related to energy transmitted to the part during sintering. The energy concentration is quantified as the Andrew's Number (AN), the inverse relationship of laser power (LP) to laser scanning speed (SSP) and scan spacing (SS). Therefore, to determine the optimal AN—and therefore increase density—an experiment varying LP and SS (SSP is a manufacturer setting) to determine their effects on apparent density and tensile strength was completed. The optimal AN, 1.63 J/cm2 for Nylon 12 powder, was based on highest apparent density and tensile strength. Using this AN, additional deflection samples were tested. Initial results showed a maximum deflection of 2.1 mm at .145 MPa for a 1.3 mm thick membrane. In comparison, changing the volume of a 3D scan of a patient's residual limb by 6% in a 10.9 cm diameter region on the posterior distal tibia socket end, as recommended by a prosthetist, requires a 5.8 mm displacement. Therefore, early results suggest that a single bladder will not meet deflection requirements, influencing the design of multiple larger regions and use of a more flexible material. Results from these experiments will help eliminate concepts which cannot deflect the necessary amount for the volume change, further refining the concepts towards a solution.

High prevalence of hearing disorders at the Special Olympics indicate need to screen persons with intellectual disability

BACKGROUND

Persons with intellectual disabilities (ID) are at increased risk for hearing impairment which often remains undetected. If left untreated, such hearing impairments may worsen the social and communicative problems of these persons. The aims of this study are to determine the prevalence of hearing impairment, to specify type and degree of hearing loss, and to evaluate the sensitivity and specificity of the screening in this population.

METHODS

During the German Special Olympics Summer Games 2006, 552 athletes with ID had their hearing screened according to the international protocol of Healthy Hearing, Special Olympics. This screening protocol includes otoscopy, measurement of distortion product otoacoustic emissions, and - if necessary - tympanometry and pure tone audiometry (PTA) screening at 2 and 4 kHz. Additionally, 195 athletes underwent a full diagnostic PTA. The results of the screening and diagnostic PTA were compared.

RESULTS

Of the 524 athletes who completed the screening protocol, 76% passed and 24% failed it. Ear wax was removed in 48% of all athletes. 42% of the athletes were recommended to consult an otolaryngologist or an acoustician. Of the 99 athletes whose screening-based suspicion of a hearing loss was confirmed with diagnostic PTA, 74 had an undetected hearing loss. The correlation (Cramer's V) between screening and diagnostic PTA was .98. The sensitivity of the screening was 100% and the specificity 98%.

DISCUSSION

The screening reliably detects hearing disorders among persons with ID. The prevalence of hearing impairment in this population is considerably higher than in the general population, and the proportion of undetected hearing impairments is large, even among people with only mild and moderate ID, as examined in this study. Therefore, a screening is highly recommended, and special attention from caregivers and professionals as well as regular hearing assessment and standard therapy programmes are required for persons with ID.

Resident condition change: should I call 911?

Identifiers of illness, including catastrophic change, are based on a set of assumptions that are not always true or accurate for older adults. Atypical findings in combination with the more subtle or different presentation of illness can result in missed opportunities for early treatment and prevention of more dire consequences. Assessment instruments described in this article can guide the investigation and communication of a resident's change in status: SPICES (Sleep; Problems with Eating and Feeding; Incontinence; Confusion; Evidence of Falls; Skin Breakdown), FANCAPES (Fluid; Aeration; Nutrition; Cognition/Communication; Activity/Abilities; Pain; Elimination; Skin/Socialization), DELIRIUM (Drug use: Electrolyte imbalance; Lack of scheduled meds; Infection; Reduced sensory input; Intracranial problems; Urinary problems; Myocardial problems), PQRST (Provokes/Palliates; Quality/Quantity; Region/Radiates; Severity; Timing) and COLDSPA (Character; Onset; Location; Duration; Severity; Pattern; Associated Symptoms), (for pain assessment). "Should I call?" scenarios are described using case studies. A systematic approach to assessment, recognition of change in functional status, protocols to guide calling for emergency assistance, and structured communication are essential elements of early recognition of illness, can reduce caregiver anxiety, and improve the health care outcomes for the resident. Imagine you or one of your staff standing in the dining room of your residence and looking at the residents for whose health and well-being you are responsible. Could you spot someone who was not doing well? Who might be ailing? If you saw 2 residents who looked ill, whom would you assess first? How would you decide? Identification of illness, including catastrophic change, is based on a set of assumptions that are not always true for older adults and can result in a set of findings that does not fit with our conventional understanding and knowledge of illness presentation. All too often, these atypical findings in combination with the more subtle presentation of illness in older adults results in missed opportunities for early treatment. A systematic approach to assessment, recognition of change, protocols to guide calling for emergency assistance, and communication with other health care providers are essential elements of early recognition of illness that can decrease health care provider anxiety and improve outcomes. This article describes 2 evidence-based assessment instruments: the SPICES tool, which should be used routinely as a first-line method for recognizing change and preventing deepening complications or acute illness, and the FANCAPES tool, which evaluates change in condition. In addition, several acronyms that can guide symptom assessment are provided. Immediately life-threatening conditions and 3 "don't miss" signs of emergencies are discussed, as are nursing interventions for the geriatric emergency. "Should I call?" scenarios are presented in a table that includes common signs and symptoms and recommended nursing actions of who to call. Two case studies illustrate the assessment instruments and analysis of data. Basic information that should be included in a transfer document is described. The article includes a communication model known as SBAR (Situation, Background, Assessment, Recommendation) that can be implemented and used by all staff of the assisted living residence.

Do all patients attending genitourinary medicine services want to be seen within 48 hours?

Summary

At a time of high capacity almost 40% of patients declined an appointment within 48 hours. Data were collected prospectively on the reasons why, and the impact of demand exceeding capacity.

Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling

A carbon-rich black layer, dating to approximately 12.9 ka, has been previously identified at approximately 50 Clovis-age sites across North America and appears contemporaneous with the abrupt onset of Younger Dryas (YD) cooling. The in situ bones of extinct Pleistocene megafauna, along with Clovis tool assemblages, occur below this black layer but not within or above it. Causes for the extinctions, YD cooling, and termination of Clovis culture have long been controversial. In this paper, we provide evidence for an extraterrestrial (ET) impact event at approximately equal 12.9 ka, which we hypothesize caused abrupt environmental changes that contributed to YD cooling, major ecological reorganization, broad-scale extinctions, and rapid human behavioral shifts at the end of the Clovis Period. Clovis-age sites in North American are overlain by a thin, discrete layer with varying peak abundances of (i) magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium, all of which are evidence for an ET impact and associated biomass burning at approximately 12.9 ka. This layer also extends throughout at least 15 Carolina Bays, which are unique, elliptical depressions, oriented to the northwest across the Atlantic Coastal Plain. We propose that one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling. The shock wave, thermal pulse, and event-related environmental effects (e.g., extensive biomass burning and food limitations) contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America.

The impact of patient-controlled analgesia on laparoscopic cholecystectomy

INTRODUCTION

Laparoscopic cholecystectomy has revolutionised the management of symptomatic gallstones and is increasingly performed as a day-case procedure. The aim of this study was to assess the impact of opioid patient-controlled analgesia (PCA) on elective laparoscopic cholecystectomy.

PATIENTS AND METHODS

In a prospective, non-randomised, observational study, 76 consecutive patients who underwent elective in-patient laparoscopic cholecystectomy were reviewed. Six patients with complicated gall stone disease and four patients who converted from laparoscopic to an open operation were excluded.

RESULTS

Of the 66 remaining in the study group, 25 patients received morphine-PCA and, of these, 9 were fit for discharge. In contrast, 41 patients did not receive PCA and, of these, 27 were fit for discharge (P < 0.05). Median Aldrete score in the PCA group was 16 and in the non-PCA group 18 (P < 0.05). Postoperative nausea and vomiting were more common in patients receiving a morphine-based PCA and with in those with higher anti-emetic requirement (10/25 in PCA and 7/41 non-PCA groups; P < 0.05).

CONCLUSIONS

Routine postoperative opioid PCA prolongs the recovery and in-patient stay following elective laparoscopic cholecystectomy. Its role in postoperative pain management in routine laparoscopic cholecystectomy should be questioned.

Evaluation of the topical hemostatic efficacy and safety of TISSEEL VH S/D fibrin sealant compared with currently licensed TISSEEL VH in patients undergoing cardiac surgery: a phase 3, randomized, double-blind clinical study

AIM

TISSEEL VH is the only commercially available fibrin sealant indicated as an adjunct to conventional methods of hemostasis during cardiac surgery. A next generation fibrin sealant (TISSEEL VH S/D) has been developed in frozen, ready-to-use form with an added virus inactivation step (solvent/detergent [S/D] treatment) to provide added safety and convenience to the currently licensed product. This study was performed to compare efficacy and safety of the two products.

METHODS

Phase 3, prospective, randomized, double-blind, multicenter study to compare TISSEEL VH S/D to TISSEEL VH during cardiac surgery. The primary efficacy endpoint was the proportion of patients who achieved hemostasis at the primary treatment site within 5 min, and maintained hemostasis until surgical closure.

RESULTS

The proportion of patients who achieved hemostasis at the primary treatment site within 5 min, and maintained hemostasis until surgical closure was 88.2% for TISSEEL VH S/D and 89.6% for TISSEEL VH in the intent-to-treat population. The difference in proportions, TISSEEL VH S/D minus TISSEEL VH, was 1.4% with a standard error of 3.70%. The lower 97.5% confidence bound of this difference was 8.6%, which is above the predefined noninferiority margin of 15%. Therefore, TISSEEL VH S/D is at least as efficacious as TISSEEL VH. The safety profile of TISSEEL VH S/D was very similar to that of currently licensed TISSEEL VH as assessed by the safety endpoints.

CONCLUSION

TISSEEL VH S/D is safe and effective for use as an adjunct to hemostasis in patients undergoing cardiac surgery.

Outcome of day-case inguinal hernia in elderly patients: how safe is it?

INTRODUCTION

Inguinal hernia repair is well established as a day-case procedure but little is reported about the outcome for elderly patients.

METHODS

A retrospective study was undertaken to compare a study group of patients aged 70 and above with a controlled group of patients aged less than 65 who had day-case inguinal hernia repair (Lichtenstein repair) between January 1996 and December 2004.

RESULTS

A total of 588 patients (282 in the elderly group and 306 in the control group) were studied. Although there were a larger number of higher-risk (ASA III) patients in the elderly group (P < 0.001), unplanned admission, postoperative symptoms, and satisfaction were comparable with those for the younger group.

CONCLUSION

Day-case inguinal hernia repair can be safely offered to patients aged 70 and above.

Artesunate�+�amodiaquine and artesunate�+�sulphadoxine?pyrimethamine for treatment of uncomplicated malaria in Democratic Republic of Congo: a clinical trial with determination of sulphadoxine and pyrimethamine-resistant haplotypes

We undertook a trial of artesunate + amodiaquine (AS + AQ) and artesunate + sulphadoxine-pyrimethamine (AS + SP) in 180 children of age 6-59 months with uncomplicated malaria in Democratic Republic of Congo. Children were randomly allocated to receive 3 days observed treatment of AS + AQ (n = 90) or 3 days of AS + SP (n = 90). Primary efficacy outcomes were 28-day parasite recurrence rates, and recrudescence rates were adjusted by genotyping to distinguish new infection and recrudescence. In addition, we determined the prevalence of molecular markers of resistance to sulphadoxine and pyrimethamine. Day 28 parasite recurrence rates were 16.9% (14/83; 95% CI: 9.5-26.7) in the AS + AQ group and 34.6% (28/81; 95% CI: 24.3-46.0) in the AS + SP group (P = 0.009). After PCR correction, recrudescence rates were 6.7% (5/74; 95% CI: 2.2-15.1) for AS + AQ and 19.7% (13/66; 95% CI: 10.9-31.3) for AS + SP (P = 0.02). There was no significant difference between the two arms in time to parasite clearance, fever clearance and gametocyte clearance. Parasite genotyping showed high frequencies of dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) molecular SP-resistance markers, with 57% of the samples showing more than three mutations linked to SP resistance, and 27% with triple-dhfr/double-dhps haplotype, confirming that SP treatment failure rates are likely to be high. AS + AQ had significantly higher efficacy than AS + SP. These results contributed to the subsequent change to AS + AQ as first-line regimen in the country. Efforts to properly implement the new protocol and maintain adherence at acceptable levels should include health staff and patient sensitization. The 6.8% recrudescence rate indicates that AS + AQ should be monitored closely until a more effective artemisinin combination therapy regimen is needed and can be introduced.

Current research priorities in chronic fatigue syndrome/myalgic encephalomyelitis: disease mechanisms, a diagnostic test and specific treatments

Chronic fatigue syndrome (CFS) is an illness characterised by disabling fatigue of at least 6 months duration, which is accompanied by various rheumatological, infectious and neuropsychiatric symptoms. A collaborative study group has been formed to deal with the current areas for development in CFS research--namely, to develop an understanding of the molecular pathogenesis of CFS, to develop a diagnostic test and to develop specific and curative treatments. Various groups have studied the gene expression in peripheral blood of patients with CFS, and from those studies that have been confirmed using polymerase chain reaction (PCR), clearly, the most predominant functional theme is that of immunity and defence. However, we do not yet know the precise gene signature and metabolic pathways involved. Currently, this is being dealt with using a microarray representing 47,000 human genes and variants, massive parallel signature sequencing and real-time PCR. It will be important to ensure that once a gene signature has been identified, it is specific to CFS and does not occur in other diseases and infections. A diagnostic test is being developed using surface-enhanced, laser-desorption and ionisation-time-of-flight mass spectrometry based on a pilot study in which putative biomarkers were identified. Finally, clinical trials are being planned; novel treatments that we believe are important to trial in patients with CFS are interferon-beta and one of the anti-tumour necrosis factor-alpha drugs.

Flexible trainees in Scotland

INTRODUCTION

Demand for flexible training is increasing. The contribution of such trainees to the trained medical workforce is not clear.

METHODS

All full time and flexible trainees in Scotland were 'tracked' at the completion of training.

RESULTS

80% of flexible trainees took up a consultant post of which 93% were in Scotland. 82% of full time trainees took up a consultant post of which 80% were in Scotland.

DISCUSSION

Flexible trainees become consultants at the same rate as their full time counterparts. They are commonly geographically tied and are therefore more likely to remain in Scotland and contribute to retention of doctors in this country.

A placebo-controlled, double-blind, randomized controlled trial of a natural killer cell stimulant (BioBran MGN-3) in chronic fatigue syndrome

BACKGROUND

Previous research has suggested that natural killer (NK) cell activity may be reduced in patients with chronic fatigue syndrome (CFS).

AIM

To evaluate the effectiveness of a putative NK cell stimulant, BioBran MGN-3, in reducing fatigue in CFS patients.

DESIGN

Randomized, double-blind, placebo-controlled trial.

METHODS

We recruited 71 patients with CFS (according to the Centers for Disease Control 1994 criteria) attending an out-patient specialist CFS service. Participants were given oral BioBran MGN-3 for 8 weeks (2 g three times per day) or placebo equivalent. The primary outcome measure was the Chalder physical fatigue score. Self-reported fatigue measures, self-assessment of improvement, change in key symptoms, quality of life, anxiety and depression measures were also included.

RESULTS

Data were complete in 64/71 patients. Both groups showed marked improvement over the study duration, but without significant differences. Mean improvement in the Chalder fatigue score (physical scale) was 0.3 (95%CI -2.6 to 3.2) lower in the BioBran group.

DISCUSSION

The findings do not support a specific therapeutic effect for BioBran in CFS. The improvement showed by both groups over time highlights the importance of placebo controls when evaluating interventions in CFS.

Minimum inhibitory concentrations of some antimicrobial drugs against bacteria causing uterine infections in cattle

The minimum inhibitory concentrations (MICs) of oxytetracycline, cephapirin, cephapirin/mecillinam, cefquinome, ceftiofur and enrofloxacin, candidate antibiotics for the principal bacteria associated with uterine infections: Escherichia coli, Arcanobacterium pyogenes and the anaerobic bacteria Fusobacterium necrophorum and Prevotella melaninogenicus, were determined by the agar dilution method. The bacteria were isolated from animals with clinical metritis and/or endometritis. For E coli, cefquinome and enrofloxacin had the lowest MIC90 and MIC50 values (< 0.06 microg/ml), and oxytetracycline and cephapirin had the highest values. For A pyogenes, oxytetracycline had the highest MIC50 value (16 microg/ml), but all the cephalosporins had values below 0.06 microg/ml. For the anaerobic bacteria, enrofloxacin and oxytetracycline had the highest MIC50 values but all the cephalosporins had values of 0.06 microg/ml or below.

Microbiological and serological study of leptospirosis in horses at slaughter: first isolations

A bacteriological survey of kidneys from 145 abattoir horses was performed, which resulted in the isolation of two Leptospira strains. The isolates were serologically typed as belonging to serogroups Australis and Pomona, and REA identified them as L. interrogans serovar Bratislava and L. kirschneri serovar Tsaratsovo, respectively. These are the first Leptospira isolates obtained from horses in Portugal and the Bratislava strain is the first serogroup Australis strain to be isolated in this country. The 145 horses were also serologically tested for leptospiral antibodies, and 37% had MAT titres #10878;1:10.

Human lead exposure in England from approximately 5500 BP to the 16th century AD

Lead concentration and isotope ratio data are presented for the tooth enamel of 77 individuals buried in England and spanning approximately 5000 years from the Neolithic until the 16th century AD. Whereas other tissues may be affected by diagenesis in the burial environment, the Pb concentration of tooth enamel is directly related to childhood exposure. This record is preserved post-mortem and over archaeological time. Tooth enamel Pb concentrations in the prehistoric period appear to be variable within the range 0.04 to approximately 0.4 ppm, with occasional higher levels. The Romano-British and medieval periods show a marked increase in Pb exposures with enamel concentrations reaching up to approximately 40 ppm. These exposures would today be associated with industrial pollution. Exposures appear to be highly variable compared with modern people, however, with many medieval individuals having very low enamel Pb concentrations comparable with prehistoric people. Lead isotope data refine this picture. We distinguish between the diverse isotopic ratios we believe to be characteristic of 'natural' exposure to Pb-from geological sources via the diet-and the much narrower isotopic range characteristic of exposure to technological Pb from ore sources. Taken together the data suggest that the maximum concentrations associated with 'non-technological' exposure at any period are approximately 0.5-1.0 ppm, similar to that reported for modern people in England.