X-ray structural, functional and computational studies of the O2-sensitive E. coli hydrogenase-1 C19G variant reveal an unusual [4Fe-4S] cluster

The crystal structure of the Escherichia coli O2-sensitive C19G [NiFe]-hydrogenase-1 variant shows that the mutation results in a novel FeS cluster, proximal to the Ni-Fe active site. While the proximal cluster of the native O2-tolerant enzyme can transfer two electrons to that site, EPR spectroscopy shows that the modified cluster can transfer only one electron, this shortfall coinciding with O2 sensitivity. Computational studies on electron transfer help to explain how the structural and redox properties of the novel FeS cluster modulate the observed phenotype.

Perforation-Invagination (PIN) Stripping of the Long Saphenous Vein Reduces Thigh Haematoma Formation in Varicose Vein Surgery

Objective:

To compare the extent of thigh haematoma formation after perforation-invagination (PIN) stripping with that occurring after standard plication stripping of the long saphenous vein.

Design:

Prospective, within-case, randomised study with analysis on an intention-to-treat basis.

Setting:

The radioisotope department of a university teaching hospital.

Patients:

Fourteen patients undergoing bilateral varicose vein surgery.

Interventions:

Red blood cell labelling in vivo with 99Tcm. Preoperative imaging of the long saphenous vein using a gamma camera. Randomisation of one leg to PIN stripping and the other to standard stripping of the long saphenous vein to the knee. Patients were reimaged 6 h postoperatively.

Main outcome measures:

The extent of thigh haematoma formation.

Results:

There was no significant difference with respect to the severity of varicosities in the long saphenous vein in the thigh between the limbs assigned to each group ( n = 11) on the preoperative images ( T = 25, 0.5> p>0.1, Wilcoxon signed rank test). Thigh haematoma in the limbs that had undergone PIN stripping of the long saphenous vein was significantly less than that in the limbs that had undergone standard stripping (T = 10, 0.05> p>0.01, Wilcoxon signed rank test).

Conclusion:

PIN stripping of the long saphenous vein results in significantly decreased haematoma formation compared with standard stripping.

Configurational and conformational classification of pyranose sugars

Automated cluster analysis is used to examine the conformation and configuration of pyranose sugars. Previous findings on this issue are confirmed, importantly from an analysis that requires no prior knowledge of the significant factors determining the conformational classification. The findings on the conformations adopted in the crystalline solid state are found to be different to existing quantum chemical calculations performed for D-glucose in the gas phase, but consistent with empirically determined conformations in the solution state. The use of this clustering analysis in studying chirality in the determined structures is discussed, as is the ability of this type of method to examine higher dimensions within the metric multi-dimensional scaling formalism.

Molecular dynamics simulations to aid the rational design of organic friction modifiers

Molecular dynamics simulations were performed under conditions of constant volume and temperature and of constant pressure and temperature to elucidate the structure activity relationships of a series of non-ionic surfactant molecules derived from vegetable fat and employed as friction modifiers in commercial engine oils. The simulations show the extent to which intermolecular hydrogen bonding is important in determining the stability of the monolayer formed by the surfactant molecules and show that mono-alkanoyl glyceride molecules are able to pack more efficiently, forming significantly more intermolecular hydrogen bonds and occupying approximately half the volume needed by di-alkanoyl glyceride molecules. Density profiles are presented which show significant mixing of the hydrophobic tail groups and a non-polar solvent. The distribution of torsion angles in the tail groups shows that the conformation is consistent with a liquid at finite temperature rather than a crystal structure. The measured friction coefficients of equimolar solutions of the glycerides show that the efficacy as friction modifiers varies in the order mono-, di- and the tri-oleyl glyceride, which is consistent with the efficacy of film formation predicted by the molecular dynamics calculations.

The multi-disciplinary evaluation of a national agri-environment scheme

With an increasing amount of public funds being spent on agri-environmental schemes effective methods have to be developed to evaluate them. As many schemes have multiple objectives there is a need for a multi-disciplinary approach to any evaluation. A method was developed to assess the degree to which ecological, landscape, historical and access objectives for the Countryside Stewardship Scheme (CSS) in England have been met. The method used a sample of 484 agreements for which data were collected from surveys, a desk study and an interview with the agreement holder. These data were then evaluated by an expert team of an ecologist, landscape architect, landscape historian, and a social scientist specializing in rural affairs. The team were subsequently brought together with a Chair to discuss their findings for each agreement, allocating scores for each of five criteria: agreement negotiation; appropriateness, environmental effectiveness, compliance and side effects. The additionality that each agreement was likely to provide was also assessed. The results of this process suggest that in the majority of cases the CSS agreements should maintain or enhance the environment in terms of ecology, landscape, and landscape history and increase public enjoyment of the countryside. Thirty-six percent of agreements showed high additionality and 38% medium additionality which demonstrates that the CSS is likely to provide a benefit to society. Agreement negotiation, predicted environmental effectiveness and predicted compliance all improved significantly over the period 1996-98. Recommendations made from this project have been implemented by the Government department to improve the CSS. The multi-disciplinary method was successful and, with further development, could be used for assessment of any agri-environment scheme, or potentially any conservation project or broader 'rural development' scheme encompassing environmental, economic and social objectives. A key to success is the need for the criteria to be tailored for the project concerned and clearly established at the beginning.

Is it safe to work with iodine-131 if you are pregnant? A risk assessment for nuclear medicine staff involved with cleaning and decontamination

In the UK, Regulation 8(5) of the Ionising Radiation Regulations 1999 (In: Work with ionising radiation. London: HSE Books, 2000) requires employers to ensure that the dose to the foetus of a pregnant worker is unlikely to exceed 1 mSv. Risk assessments are required which are capable of predicting the total foetal dose. Work involving 131I is a particular problem. Foetal dose coefficients from the maternal intake of 131I for all stages of pregnancy have been published (Phipps AW, Smith TJ, Fell TP, Harrison JD. Doses to the embryo/fetus and neonate from intake of radionuclides by the mother. NRPB contract research report 397/2001. Didcot, Oxon.: National Radiological Protection Board (NRPB), 2001. Available on website www.hse.gov.uk/research/crr_pdf/2001/crr01397.pdf), and range from 0.08 microSv x kBq(-1) at conception to 55 microSv x kBq(-1) at week 35. This paper examines one aspect of work in a nuclear medicine department in which the source of 131I is uncontrolled to determine whether the risk assessment indicates that restrictions should apply to a pregnant member of staff. Following in-patient treatment with 131I, rooms are checked and decontaminated before being decontrolled. Cleaning staff were monitored immediately after the cleaning process with hand-held detectors and by whole-body monitoring. Total body contamination ranged up to 3.2 kBq; after a change of clothing, the maximum remaining activity was 0.68 kBq. Acquired contamination correlated with the total activity administered to the patient. Hand-held monitoring rarely detected contamination. Whole-body monitoring indicated that the levels of contamination encountered could lead to a dose limit for the foetus being exceeded. These levels are very difficult to detect with hand-held monitoring. The conclusion to be drawn is that pregnant staff should be excluded from situations in which accidents could arise, or where the source of 131I is uncontrolled or unpredictable.

Inhibition of cancer cell growth by ruthenium(II) arene complexes

Inhibition of the growth of the human ovarian cancer cell line A2780 by organometallic ruthenium(II) complexes of the type [(eta(6)-arene)Ru(X)(Y)(Z)], where arene is benzene or substituted benzene, X, Y, and Z are halide, acetonitrile, or isonicotinamide, or X,Y is ethylenediamine (en) or N-ethylethylenediamine, has been investigated. The X-ray crystal structures of the complexes [(eta(6)-p-cymene)Ru(en)Cl]PF(6) (5), [(eta(6)-p-cymene)RuCl(2)(isonicotinamide)] (7), and [(eta(6)-biphenyl)Ru(en)Cl]PF(6) (9) are reported. They have "piano stool" geometries with eta(6) coordination of the arene ligand. Complexes with X,Y as a chelated en ligand and Z as a monofunctional leaving group had the highest activity. Complexes 5, 6 (the iodo analogue of 5), 9, and 10 (ethylethylenediamine analogue of 9) were as active as carboplatin. Hydrolysis of the reactive Ru-Cl bond in complex 5 was detected by HPLC but was suppressed by the addition of chloride ions. Complex 5 binds strongly and selectively to G bases on DNA oligonucleotides to form monofunctional adducts. No inhibition of topoisomerase I or II by complexes 5, 6, or 9 was detected. These chelated Ru(II) arene complexes have potential as novel metal-based anticancer agents with a mechanism of action different from that of the Ru(III) complex currently on clinical trial.

Short intramolecular S...O interactions in S-substituted 2-mercaptoacetophenones

The non-bonded S...O intramolecular interactions in the title compounds 2-(phenylthio)acetophenone [IUPAC: 2-[2-(phenylsulfanyl)phenyl]ethanone], C(14)H(12)OS, and 2-(benzylthio)acetophenone [IUPAC: 2-[2-(benzylsulfanyl)phenyl]ethanone], C(15)H(14)OS, are unusually short, indicating the contribution of heterocyclic oxathiole-type resonance structures to the overall bonding.

The Bene-Anthony Family Relations Test revisited: directions in the assessment of children's perceptions of family relations

The Bene-Anthony Family Relations Test is designed to assess the child's perception of family relations using projective techniques. This article describes the test and background to its development. The validity of the test is limited by the content of some items and their categorization, though there is evidence that the test can distinguish between populations that differ on other related variables. A survey of professionals who use the test is described. Despite their enthusiasm for it, the majority of respondents had modified the test in some way, and 86% regularly rephrased at least one item from the test. There were several criticisms of the test, including the positive scoring of 'sexualized items'. The respondents were also inconsistent in their administration and scoring of the test. This test is used less frequently in research, possibly because it is not perceived as a sufficiently robust psychometric instrument. However, there is a danger of 'throwing away the baby with the bath water'. Recommendations are made for the development of a test that reliably assesses the child's perception of the emotional content of relations.

Abnormal hepatic perfusion index predicts recurrence of colorectal carcinoma

OBJECTIVE

The hepatic perfusion index (HPI) is a ratio of the gradient of hepatic arterial to total hepatic blood flow. This study correlated HPI with histopathological indicators of prognosis and disease-free survival following curative resection of colorectal cancer.

PATIENTS AND METHODS

HPI was measured preoperatively by dynamic hepatic scintigraphy in 37 patients with a primary colorectal cancer and no evidence of distant metastases who underwent a curative resection.

RESULTS

Abnormally elevated HPI were detected in 49% of patients and were significantly more frequent in association with locally advanced tumours (T3 and T4) in comparison with early tumours (T1 and T2; 59% vs 20%, respectively; P=0.04). There was no association between abnormal HPI and presence of lymph node metastases or degree of tumour differentiation. The 18-month disease-free survival rate of patients with abnormal HPI was significantly shorter than that of patients with normal HPI (53% vs 100%, respectively; P=0.01), and this was independent of the T category.

CONCLUSION

HPI predicts the risk of recurrent colorectal carcinoma, and this measurement should be included in the panel of prognostic markers in future clinical trials.

A family of polynuclear cobalt and nickel complexes stabilised by 2-pyridonate and carboxylate ligands

The synthesis and structural characterisation of a series of cobalt and nickel cages are reported. Eight of these structures contain a [M10(mu3-OH)6(eta2, mu3-xhp),(eta2, mu2-O2CR)6]2+ core (where M = Co or Ni; xhp = 6-chloro- or 6-methyl-2-pyridonate: R = Me, Ph, CHMe2, CH2Cl, CHPh2 or CMe3), where the ten metal atoms describe a centred-tricapped-trigonal prism (ttp). The cage contains six hydroxide ligands around the central metal, and the exterior is coated with pyridonate and carboxylate ligands. For four of the cages additional metal centres are found attached to the upper and/or lower triangular faces of the trigonal prism, generating dodeca- and undecanuclear cages. Three further cages are reported that contain a metal core based on an incomplete centred-tetraicosahedron. These cages involve trimethylacetate as a ligand in company with either 6-methyl-2-pyridonate or 6-chloro-2-pyridonate. Comparison of these latter structures with the trigonal prisms reveal that they can be described as a pentacapped-trigonal prism missing one edge. Magnetic studies of three of the nickel cages with trigonal prismatic cores show spin ground states of S = 8, 4 and 2 for Ni12, Ni11 and Ni10 cages, respectively.

Characteristics of children and adolescents presenting to accident and emergency departments with deliberate self harm

OBJECTIVES

The aim of this study was to provide a description of the characteristics of children and adolescents presenting to the accident and emergency (A&E) department with deliberate self harm.

METHODS

Descriptive analysis of data collected by reviewing the notes of all children and adolescents aged 16 years and under, presenting during the period of study (1 January to 31 December) with a history of deliberate self harm.

RESULTS

A total of 100 children (18 boys, 82 girls) were responsible for 117 episodes of deliberate self harm. Nine repeaters were responsible for 22% of the attendances; 38% had made use of emergency ambulance service and 6% were referred by their general practitioner (GP). Sixty nine per cent were accompanied by immediate family and 21% children presented alone. Seventy four per cent presented within three hours of the attempt and 37% presented between 6 pm and midnight; 77% presented during weekdays and 30% of attempts had occurred during spring. Ninety two per cent had used a pharmaceutical drug. Sixty five per cent had made the attempt at home and 12% in a public place. Twenty five per cent had prior or current contact with the child psychiatric services and a similar proportion had prior or current contact with social services.

CONCLUSIONS

Few of the children and adolescents presenting with deliberate self harm to the A&E department have been referred by their GP. They frequently present alone or are accompanied by people who are not family members making assessment and treatment difficult. Many already have other services involved in their care and thus the gathering and dissemination of information can become quite lengthy. The time of presentation is usually out of hours, further complicating this process. A small number of young people present with repeated self harm, who are known to be most vulnerable for completing suicide.

Criterion-based validity of an intracarotid amobarbital recognition-memory protocol

PURPOSE

We tested whether the behavioral components of an Intracarotid Amobarbital Protocol (IAP) had criterion validity. It was hypothesized that a recognition-memory test designed for intracarotid injections and used to predict the risk of global amnesia before an elective temporal lobectomy should also identify persons who are severely amnesic due to other neurologic causes. Divergent validity predicts that speech tasks would be unaffected by amnesia. Test-retest reliability also was measured.

METHODS

Fifteen persons with severe amnesia were administered four alternate forms of a yes/no recognition-memory protocol and a speech protocol. No drug injection occurred. Standardized neuropsychological tests were used to divide the amnesic group into those with Global Amnesia (i.e., retain no ongoing memories), Severe Amnesia (i.e., memory impaired), and Amnesia Plus (severe amnesia plus other neuropsychologic deficits).

RESULTS

Two persons with Global Amnesia obtained scores at or below chance (i.e., failed) on the memory protocol. Unexpectedly, 12 of 13 severely amnesic persons obtained near-perfect memory scores. Amnesia had no impact on the speech protocol. Pass/Fail outcomes were highly correlated across all four sets.

CONCLUSIONS

A four-item IAP memory protocol showed good reliability and criterion validity in identifying the rare condition of Global Amnesia, but it was insensitive to other disabling, severe amnesic disorders. This IAP memory protocol might have validity in predicting a postsurgical Global Amnesic disorder, but it did not identify and therefore could not predict other more common severe amnesic disorders.

Improvement of nebulised antibiotic delivery in cystic fibrosis

AIM

To investigate deposition patterns and to assess the delivery rate of two nebuliser systems in children with cystic fibrosis (CF).

METHODS

Thirty three children with CF on regular treatment with nebulised antibiotics had radioisotope scans performed using technetium-99m labelled aerosol antibiotic generated by a Ventstream nebuliser (median mass diameter (MMD), 3.3 microm; delivery rate, 0. 075 ml/min) under conditions similar to their routine home practice. The inhomogeneity of the images was scored on a 1-10 rating scale (a low score indicating even distribution of the antibiotic), and stomach deposition was measured as a percentage of overall deposition. Twenty patients had a repeat scan using an Optimist nebuliser (MMD, 1.8 microm; delivery rate, 0.02 ml/min).

RESULTS

The mean inhomogeneity scores were 5.4 in the Ventstream group and 3. 5 in the Optimist group. Mean stomach deposition was 17.3% in the 33 patients using the Ventstream nebuliser. There was an inverse relation between height and stomach deposition (r = 0.69). In the 20 patients who had both nebulisers, the mean percentages of stomach deposition for the Ventstream and Optimist nebulisers were 11.8% and 1.6%, respectively. The Ventstream nebuliser delivered antibiotic at an average 2.8 times faster rate than the Optimist nebuliser.

IMPLICATIONS

A smaller particle size results in a more homogenous distribution of the antibiotic in the lungs with decreased stomach deposition. This should not be seen as a recommendation to use the Optimist nebuliser because more antibiotic was delivered to most parts of the lung with the Ventstream because of its increased delivery rate.

Assessing clot lysis strategies using a simplified mathematical model

This paper attempts to describe lysis of a clot by infusion of lytic agent using a simple geometrical approach, in which the rate of clot lysis is assumed proportional to the exposed surface of the clot and the concentration of lytic agent. Six simple realizations (a)-(f) of this basic model are developed which account for the dependence of clot lysis time on five different clot geometries. In all six cases the clot is initially described as a uniform cylinder which totally occludes a vessel. In model (a) lysis proceeds as an advancing front at the proximal face of the clot. In model (b) lysis proceeds radially outwards from the central axis of the vessel while in model (c) lysis occurs radially inwards from the surface adjacent the wall, of the cylinder. In models (d) and (e) it is assumed that the clot breaks into a uniform spherical and cylindrical fragments, respectively, while model (f) uses the spherical fragment model combined with a lytic agent concentration which decreases with time. The validity of the models was assessed using previously published data from 76 patients in whom lysis time and clot size were recorded. Least squares linear regression analysis based on the six model equations yielded highly significant correlation coefficients r2 of 0.457, 0.412, 0.412, 0.495, 0.469, 0.663 for models (a)-(f), respectively. The results suggest that when a constant lytic agent concentration is assumed, no single geometry accounts for significantly more variation than any other, but that a combination of varying lytic agent concentration and clot geometry significantly influences clot lysis time and accounts for much of the observed variation.

Physiotherapy and occupational therapy for juvenile chronic arthritis: custom and practice in five centres in the UK, USA and Canada

Physiotherapy and occupational therapy are widely accepted as being of central importance for the treatment of juvenile chronic arthritis (JCA). However, these approaches have rarely been subject to critical scrutiny. The aims of this report are to highlight some of the inter-centre similarities and differences observed in the implementation of physical and occupational therapy for JCA, and to emphasize the need for scientifically controlled research in this area. During a series of visits to several paediatric rheumatology units in the UK, USA and Canada, three aspects of the service were noted: treatment philosophy, physical interventions used for the treatment of JCA and quality-of-life and independence training activities. There was general consensus with the philosophy that early physical intervention was a vital part of the treatment plan for JCA, although all therapists were concerned that compliance with treatment modalities was poor. Differences between units in the approach to acute arthritis, the use of foot orthoses and wrist splints, the treatment of joint contractures and the use of general quality-of-life training activities were noted. Although it was widely recognized that controlled research into the efficacy of physical intervention was needed, no centre had a co-ordinated plan for such investigations.

Perfusion defects in vibration white finger: a clinical assessment using isotope limb blood flow

Vibration white finger is a vasospastic disorder caused by long-term exposure to vibration tools. In an attempt to assess the extent of obliterative vessel disease in this disorder, hyperaemic hand blood flow was measured using technetium-labelled human albumin and a gamma camera. This method quantitates blood flow in ml/100 ml of tissue per min in addition to providing a perfusion image used to assess vessel disease. A perfusion score is then given to this image to reflect the extent of disease. The results of this study demonstrate that 78% of patients with vibration white finger had evidence of organic vessel disease. Moreover, patients with advanced disease tend to be bilaterally affected. The use of this simple method is advocated to aid in the diagnosis of vibration white finger; this may be particularly important for medicolegal purposes.

Bioisosters of the diphosphate group in activated forms of antiherpes virus agents. A theoretical study

In order to identify potential bioisosteric replacements for the diphosphate moiety, which is present in activated forms generated from antiherpes virus agents during their inhibitory action against herpes viruses, 5'-phosphonoacetamido (4) and 5'-O-sulfamoylcarbamoyl (5) derivatives of idoxuridine were synthesised as analogues of idoxuridine 5'-diphosphate (6). In this paper we report on the antiherpetic activity of 4 and 5. Moreover, a theoretical study is presented in which both the conformational and the electronic characteristics of 4 and 5 are compared with those of the diphosphate metabolite of idoxuridine (6), in order to verify the possibility of bioisosterism relationship between the phosphonoacetamido, the sulfamoylcarbamoyl and the diphosphate group.

Radionuclide limb blood flow measurements to resolve diagnostic problems in vascular surgery

This paper describes the application of radionuclide limb blood flow measurements in 60 patients presenting to the vascular surgeons with exercise-induced leg pain. All patients were considered to be diagnostic problems since either their symptoms were atypical for peripheral vascular disease, or they had normal peripheral pulses and/or a normal ankle/brachial pressure index. Thirty-one patients were ultimately shown to have peripheral vascular disease and underwent treatment. In all these cases the limb blood flow to one or both legs was below the normal range. Twenty-three patients were shown, by myelography, computed tomography or plain radiography, to have orthopaedic disease and in all cases their limb blood flow to both legs was within the normal range. In five patients, the limb blood flow was normal and the symptoms spontaneously resolved, no cause for the leg pain having been found (one patient refused angiography). Radionuclide limb blood flow is a simple and reliable diagnostic test which is superior to the assessment of peripheral pulses or their ankle to brachial pressure index in resolving diagnostic problems in vascular surgery.

Antiherpes virus agents: a review

In this review, after some considerations about the structure of the virus and the viral replicative cycle, herpes virus diseases in man are described. The most important antiherpes virus drugs until now discovered are then reported analyzing and examining their chemical structure related to their mechanism of action and their pharmacological activity. Finally, defects of antiherpes virus drugs currently in therapy are shown, in order to outline which directions future developments will have to follow.

Novel acyclonucleotides: synthesis and antiviral activity of alkenylphosphonic acid derivatives of purines and a pyrimidine

A series of phosphonoalkenyl and (phosphonoalkenyl)oxy derivatives of purines and a pyrimidine were synthesized. These compounds are the first reported acyclonucleotides which incorporate the alpha,beta-unsaturated phosphonic acid moiety as the phosphate mimic and include compounds in which the acyclic substituent is attached to N-9 of a purine or N-1 of a pyrimidine by either a nitrogen-carbon or a nitrogen-oxygen bond. The phosphonoalkenyl-substituted compounds 7a-c, 8a-c, 9, 10, and 12 were prepared either by Mitsunobu coupling of alcohols with purine or pyrimidine derivatives or by alternative alkylations of the heterocyclic bases. The (phosphonoalkenyl) oxy derivatives 7d-g, 8d-g, and 11 were synthesized by coupling of alcohols with 9-hydroxypurines or a 1-hydroxypyrimidine under Mitsunobu conditions. The novel acyclonucleotides were tested for activity against herpes simplex types 1 and 2 (HSV-1 and HSV-2), varicella zoster virus (VZV), cytomegalovirus (CMV), visna virus, and human immunodeficiency virus type 1 (HIV-1). Guanine derivatives were moderately to extremely cytotoxic, but the adenines were less toxic to cells. At the concentrations tested, (Z)-isomers in the unbranched series had no activity against herpes viruses or HIV-1. (E)-9-[(4-Phosphonobut-3-enyl) oxy]adenine (7d) displayed selective activity against HIV-1, (E)-2,6-diamino-9-(4-phosphonobut-3-enyl) purine (9) showed selective antiretrovirus activity, and (E)-9-[2-(hydroxymethyl)-4-phosphonobut-3-enyl]adenine (7c) showed selective antiherpesvirus (VZV and CMV) activity.

An analysis of a radionuclide technique used to measure reactive hyperaemia in limbs

A radionuclide technique (PT) for measuring the blood flow to a limb during reactive hyperaemia is described and analysed. Patients are positioned with lower limbs within the field of view of the gamma camera and pneumatic cuffs are placed below the knees to isolate the blood and induce a hyperaemic response. The remaining blood pool is labelled with 99Tcm-human serum albumin. Following release of the occlusion the rate of inflow to the limb of the radionuclide is measured and hyperaemic flow then determined, during the initial phase of the hyperaemia. The results may be analysed using a single compartment to represent the vascular pool in the lower limb. During the initial phase, activity entered the pool at a constant rate from which the blood flow may be calculated. Results were obtained in a group of 20 normal control volunteers and 20 patients with occlusive arterial disease. They indicate that following release of the cuff the blood flow rises rapidly (within 1-2 s) to a constant value which is maintained for at least 10-12 s in normal subjects and a longer period in arteriopaths. The mean flow in the normal group was 14.4 ml/100 ml min-1 and in the arteriopathic group was 4.6 ml/100 ml min-1. The constant flow measured by PT during the initial phase of reactive hyperaemia appears to differ from the results of venous occlusion plethysmography and washout of a freely diffusible tracer and possible reasons for these differences are discussed.

Hepatic perfusion index: a multicentre trial

The reproducibility and accuracy of the hepatic perfusion index (HPI) was examined by consideration of in vitro and in vivo factors. A phantom was used to simulate liver blood flow and data acquired on nine gamma cameras. Dynamic hepatic scintigraphy was undertaken on 28 patients at two centres and values obtained for the HPI. Results from the phantom study showed good agreement between the nine cameras and also with the HPI values predicted from the measured phantom flow rates. The results of the patient study indicated a high degree of conformity between observers (r = 0.95, S.E = 0.03) but poorer correlation between the HPI values from the two centres (r = 0.67, S.E. = 0.09). These results imply that centres wishing to use HPI clinically should establish their own range of normality.