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Ceftriaxone is a broad-spectrum cephalosporin that may be one option to treat methicillin-susceptible Staphylococcus aureus (MSSA). Although MSSA may be susceptible to ceftriaxone, the minimum inhibitory concentration (MIC) is generally two- to four-fold higher than other susceptible bacterial pathogens. This study aimed to explore the pharmacodynamics of ceftriaxone against MSSA and to determine the likely optimal dose. A hollow-fibre infection model was used with one clinical MSSA isolate (MIC = 4 mg/L) at an initial inoculum of 1 × 10

This study estimated the cost-effectiveness of infant rotavirus vaccination with Rotarix in the UK, taking into account community rotavirus infections that do not present to the healthcare system. A Markov model compared the costs and outcomes of vaccination versus no vaccination in a hypothetical birth cohort of children followed over a lifetime, from a societal perspective and the perspective of the National Health Service (NHS). The model estimated costs and quality-adjusted life-years (QALYs) lost due to death, hospitalisation, general practitioner (GP) consultation, emergency attendance and calls to NHS Direct for rotavirus infection in children aged

The Cassini Program is the last of the large interplanetary spacecraft missions. The Integration Test Laboratory (ITL) at the Jet Propulsion Laboratory (JPL) is part of the Cassini Program. This laboratory includes the Attitude and Articulation Control Subsystem (AACS) testbed. This environment was used to not only verify and validate the AACS, but was also used to develop advanced concepts and ideas for use in future testbed environments. The concepts developed for the AACS testbed included the use of multiple computers, real-time data collection and real-time display, Internet access, and the incorporation of commercially-available components. These concepts resulted in improved simulation fidelity, repeatable operation and reduced future operational costs. This focuses on a description of the testbed, lessons learned, the innovations used, and future directions that will substantially reduce future testbed costs.

Indonesian thin tail (ITT) sheep have a major prolificacy gene ( FecJ F ), the frequency of which is higher in the new born lambs, than in the remainder of the flock when mating is random, because carrier ewes produce more progeny than do non carriers. The frequency of the gene may vary between flocks, but remains relatively stable in flocks with established husbandry procedures. The countermanding selection pressures maintaining the equilibrium value for the frequency of FecJ F are mainly those deriving from higher mortality rates of lambs in larger litters. Embryo survival is not significantly different across the range of ovulation rates in ITT ewes, in contrast to observations in other prolific breeds. Generation intervals and the incidences of metabolic and infectious diseases in ewes carrying larger litters can also affect the frequency of FecJ F in flocks. In turn, each of the factors affecting the frequency of FecJ F is modulated by the level of nutrition and management in each flock. The distribution of prolificacy genotypes in the ewes of a standard flock is calculated as FecJ F FecJ F /12; FecJ F FecJ + /44; FecJ + FecJ + /44 giving a frequency of 0.34 for FecJ F . The frequency of FecJ F is then 0.43 in the lambs at birth, when their numbers have been amplified in the carrier ewes. There are heavier metabolic demands on ewes carrying larger litters and the foetuses constitute a higher proportion of weight gain during pregnancy. Consequently, more of the lambs of carrier ewes are smaller and weaker at birth, and the reserves of the ewes for colostrum and milk production are depleted. When low lamb survival rates in larger litters are considered, the frequency of FecJ F falls to 0.35 in the lambs at weaning in lean years and 0.38 in middling years. At a high level of husbandry, ewe weight gains during pregnancy and lamb survival rates improve substantially, and after 3 years, the frequency of FecJ F in the lambs at birth is estimated to have risen to 0.49; and 0.47 at weaning.

A cylindrical microwave resonant cavity operating in the TE011, mode was used to study the dielectric response of SrTiO3 and YiBa2CU3Ox. The microwave dielectric response of the powdered samples of these materials is studied as a function of temperature at a frequency of 10.6 GHz. For this study, a very precise heating and cooling system was designed to control the temperature accurately to a tenth of a degree. The real and imaginary parts of the complex permittivity were studied using Slater’s Perturbation equations. The relaxation times of these materials are derived using Debye’s equations for polar molecules.

resistance is heritable. In order to re-evaluate this evidence, 20 ITT sheep were infected with 350 metacercariae of F. gigantica and for comparison, 10 St. Croix sheep, 10 Merino sheep and 20 crossbred of ITT x St. Croix sheep were also infected with the same dose of metacercariae. The results showed that ITT sheep was highly resistant than the other breed, whereas St. Croix and Merino sheep were susceptible. 60% of the crossbred were as resistant as ITT sheep and the other 40% were as susceptible as the St. Croix sheep. Thus, it is proposed that there might be a hereditary resistance factor such as a dominant gene which inducing the mechanism of resistance in ITT sheep, and there is some indication that IgG2 might act as a blocking antibody that interferes the mechanism of resistance.

Rapidly progressive cases of primary idiopathic hip osteoarthrosis are well known and recognized. Their prevalence and significance are, however, often poorly appreciated. This article aims to assess the prevalence of the condition in a United Kingdom district general hospital. Several points arise: 1) Patients suffering rapid deterioration do not always alert their surgeon to the worsening symptoms; 2) Waiting lists need regular administration and the patients regular review while on such lists; 3) Decisions about surgery and case selection should be made purely on clinical grounds with financial, political, and administrative considerations accorded little or no relevance.

Metal-ceramic microstructures were formed in situ by the partial reduction (i.e. the reduction of only one of the metallic elements) of the spinel compound NiAl 2 O 4 . Depending on reduction conditions, these microstructures consist of Ni particles embedded in an α-Al 2 O 3 or a multiphase matrix called ‘defect spinel’. The volume shrinkage that accompanies the reaction generates residual stresses which profoundly affect the microstructure evolution. Conversely, formation of metastable, intermediate phases, generation of porosity and cracking are all observed and may act to relax the residual stresses. Electron microscopy observations as well as both neutron and X-ray diffraction residual stress measurements are used to study the influence of residual stresses on the microstructure evolution during the reduction process.

The effects of three distinct thermo-mechanical processes on the residual stress state in a uni-directionally reinforced SCS-6/Ti-6-2-4-2[0]6 titanium-alloy matrix composite were predicted using a finite element model. For comparison the residual stresses were measured using X-ray and neutron diffraction. Reductions in stress were predicted by the models and both experimental techniques recorded a reduction compared to the as-fabricated material. While the numerically predicted trends qualitatively agreed with the neutron measurements quantitative agreement was not achieved. In the longitudinal direction the neutron results showed closer agreement to the calcualtion whereas in the transverse direction the X-ray results did. Nevertheless the changes did correlate with improvement in fatigue lifetimes.

The genetic basis of the high resistance of Indonesian Thin Tail (ITT) sheep against Fasciola gigantica has been studied by measuring the resistance levels of ITT sheep, St. Croix sheep and their F2 and F3 crossbreds. All of the sheep were bred and reared in the same environment. Approximately half of the F2 and F3 crossbreds were as resistant as the ITT parental breed, one-quarter had the low resistance of the St. Croix parental breed and the rest had an intermediate level of resistance. It is concluded that the high resistance is determined by a major gene with incomplete dominance. The prevalence of the gene in the ITT sheep population is estimated to be about 90%. The resistance may be innate or acquired; but, regardless of the mechanism, it could be used to control fasciolosis caused by F. gigantica by breed substitution or by crossbreeding with other breeds of sheep.

High resistance of Indonesian thin tail (ITT) sheep against Fasciola gigantica has been confirmed. Naive ITT sheep had only 17% of the number of mature parasites collected from control St. Croix sheep. In contrast, the level of resistance of ITT sheep against F. hepatica was the same as that of the low resistance Merino breed after both primary and secondary infections. It is suggested that resistance of ITT sheep against F. gigantica was manifested in two phases. The major phase appeared to be specific to the ITT sheep : F. gigantica relationship, acting against immature parasites in both naive and previously exposed hosts and could be innate or acquired. The second phase appeared to be specific to F. gigantica, and was acquired, because it killed young adult parasites only after secondary infection. F. gigantica from ITT sheep were heavier than those from the St. Croix sheep, possible because feeding was impaired by more extensive liver damage in the latter. Approximately 45 F. gigantica killed 25-kg sheep before and during migration from the liver parenchyma into the bile ducts. Death was caused by haemorrhages into the liver parenchyma, bile ducts and peritoneum.

Rapidly progressive cases of primary idiopathic hip osteoarthrosis are known and recognised by all orthopaedic surgeons. Their prevalence and significance are, however, often poorly appreciated. This article reviews the subject and assesses the relevance of the condition to a UK district general hospital. Several points arise: 1.1. Patients suffering rapid deterioration do not always alert their surgeon to the worsening symptoms; 2.2. Those who have experience of operating on rapidly progressive cases note the technical difficulties and compromised outcome; 3.3. Waiting lists need regular administration and the patients regular review while on such lists; 4.4. Decisions about surgery and case selection should be made purely on clinical grounds with financial, political and administrative considerations in a distant secondary position.

A common approach to analyzing the performance of a spread-spectrum communication system in fading is to assume that the multipath profile is a constant function of delay. However, different multipath profile models can lead to significant differences in predicted system performance, so caution should be exercised when choosing a particular model for analysis. Several previous studies show that a good fit to the experimentally measured multipath profile of indoor wireless channels is an exponential function. Assuming Rayleigh fading and an exponential multipath profile, in this paper we derive a closed form expression for the bit error rate of biphase-shift-keying and an upper bound for trellis-code-modulation both with combined spread-spectrum and antenna diversity. Comparison of these results with simulated results based on actual indoor channel measurements shows that the exponential profile model differs from the simulation model by only 1-2 dB whereas the constant profile model differs by as much as 5 dB. >

Indoor wireless channels which fade because of reflections from the building structure and the objects within the building have been experimentally found to fit either Rayleigh or Rician statistics. Digital communications performance has been calculated for these models, although in the Rician case numerical methods are typically employed. The authors present the closed form solution for DPSK in slow, flat, Rician fading, specifically for those values of specular-to-random ratio which have been determined experimentally to characterize Rician fading indoor environments. They then determine the performance loss as a function of the specular-to-random ratio. Finally, the results are generalized for a packet of N bits. Several useful approximations are also presented. >

When a digital communication system transmits data in packet (block) form, straightforward techniques exist for computing the probability that at least one bit in the packet of N bits is in error. For differential phase-shift-keying (DPSK) or differentially encoded coherent biphase-shift-keying (DE-BPSK), the paired error tendency precludes the simpler computational approach used, for example for straight BPSK, if precise results are required. The exact expression for the probability of a packet error is derived for both DPSK and DE-BPSK. It is shown that ignoring the paired error tendency and using the simpler independent bit error assumption yields an upper bound which, for large packet sizes, is in error by no more than approximately 0.1 dB for DPSK and 0.2 dB for DE-BPSK. An excellent approximation is derived for both cases; that is useful for precise results. >

The development of chemical analysis techniques over the past decade has made a significant contribution to the overall progress in Hg 1−x Cd x Te (MCT) and related materials as well as device studies. This review summarises the main techniques which are currently available for the measurement of composition, x, and impurity levels. Many techniques have been used to determine x, the most widely used being that of infra-red transmission, but most have to be calibrated back to known standards. These standards are quantified by Atomic Absorption Spectrometry (AAS) measurements. The latter technique also is used to provide the accurate measure of many impurity and dopant elements

Recent government and public concern about the recorded increase in human salmonellosis in the UK and abroad has stimulated investigations of both the causes and consequences of these infections. This paper discusses the framework for economic analysis of food-borne disease and problems associated with the estimation of costs. A brief review of the literature in this area is given and the results of a national study of the costs of human salmonellosis in England and Wales are presented and used to estimate the likely costs of S. enteritidis infection.

Treatment of bovine calves 10-16 days old with an anthelmintic which is effective against immature Toxocara vitulorum killed the parasites, there was no new infection and recontamination of the environment was precluded. When the management of the program was delegated to the livestock officers, approximately 3% of calves scheduled for treatment developed patent infections. The prevalences of toxocarosis on the different farms were correlated with annual rainfall, probably because the longer dry periods associated with lower rainfall killed infective eggs in the environment. The treatment schedules prevailing before the study commenced were ineffective. The prevalence of toxocarosis in the bovine calves on farms in the area with an annual rainfall of about 1000 mm was lower than that in buffalo calves studied previously in the same area.

Suicidal jumping from a height appears to be a seasonal problem in Glasgow. A series of 58 individuals were studied, giving a total of 60 jumping incidents. Of these, 21 were killed outright, and of 31 reaching hospital a further 11 subsequently died. Many were young, single, unemployed, adult males, the majority of whom had a known psychiatric diagnosis. Jump heights ranged from 1 to 27 floors and jumps from more than 6 floors were almost always fatal. Below this height mortality was related to the attitude of fall. Overall, 50 per cent mortality occurred at the 3rd floor. A wide range of multiple injuries were sustained and the Injury Severity Score was used to grade these for quantitative comparison. This was found to be highly discriminating between survival and non-survival.

The roles of various analytical techniques for both matrix element composition and impurity content of cadmium mercury telluride and related materials are reviewed from the viewpoint of a user. The main techniques considered are infrared (IR) transmission, atomic absorption spectrometry (AAS), X-ray flourescence (XRF), electrolyte electroreflectance (EER), Rutherford backscattering (RBS), spark source mass spectrometry (SSMS), laser scan mass spectrometry (LSMS) and secondary ion mass spectrometry (SIMS). The role of these techniques in the analysis of bulk materials, epitaxial layers and device structures is considered. It is shown that whilst SIMS can uniquely provide analytical information with excellent depth and lateral resolution, some compositional and purity information can also be achieved more cost-effectively using developments of what may be considered more “traditional” techniques. Laser scan mass spectrometry is shown to be an interesting alternative to SIMS for high sensitivity general analyses when depth and spatial distributions are not required.

A procedure for labelling hatched Toxocara vitulorum larvae with 75 selenium is described. Labelled larvae are infective when administered into the small intestine and portal vein of buffalo of all ages. Only very young calves are infected after oral administration. The labelled larvae are used with an enhanced fluorographic autoradiographic procedure to study the dynamics of the infection in non-pregnant and pregnant buffalo. Larvae penetrate the wall of the small intestine between 2 and 8 h after administration. Most larvae go straight to the liver via the portal vein but a few enter the mesenteric lymph nodes. Over the next 90 h some larvae migrate to the lung and a few to muscle, brain, kidney and peripheral lymph nodes. Most remain in the liver. Over the next 3-7 weeks the larvae grow by about 10% and no moulting is observed. In a pregnant host larvae grow to 500-600 microns in liver and lung 1-8 days before parturition and migrate to the mammary gland around the time of parturition. In the mammary gland they grow to about 1200 microns and pass into the milk during the 7 days after parturition.

Experimental studies of the dielectric response in liquid crystals at different temperatures have been performed using a microwave cavity spectrometer. The data on the width of the resonant profile and the shift of the resonant frequency observed are analysed to determine permittivity, dielectric loss, and relaxation time mechanism. The relative variation of the dielectric loss has been measured at different temperatures to monitor the phase changes. This work provides useful information about the macroscopic structure of the liquid crystals.

Ameritech's view of IN (intelligent network) Release 0 is described, and some of the technical issues to be addressed as the intelligent network evolves over the time period 1991 to 1995 are highlighted. The service switching point (SSP), which resides in local or tandem switching systems, is a critical component of the IN architecture and provides functionalities required and used by the service designer. The IN Release 0 SSP-SCP (service control point) interface is the initial step in developing a flexible service-independent interface, enabling switching programmability for the intelligent network. Initial implementation is planned for the existing generation of digital switches, and IN will evolve to extend its usefulness to the service designer. >

A reliability assurance technique for analyzing field data is discussed. Data are accumulated from field service reports and entered on a computer, using dBase III. The data are processed, and tables and graphs are prepared for analysis. Various reliability characteristics, such as mean time between failures and reliability growth, are determined. A report is prepared which is shared with members of the project team, by whom appropriate action is taken. >

Direct sequence spread spectrum (DS-SS) is an efficient method to combat multipath fading and interference, especially when combined with mitigation techniques like channel coding and diversity. The authors evaluate bounds to the performance of trellis codes in combination with conventional diversity for a DS-SS code division multiple access (CDMA) system in the indoor environment, modeled by a slowly varying, Rayleigh fading, discrete multipath channel. A Gaussian approximation for the multiuser interference, a star network configuration, and average power control are assumed. The index of performance is the average bit error probability. It is shown, for a given average error probability, that there is considerable improvement in the number of users supported by the subject system when compared with systems with either coding or diversity alone. >

The number of users in a cellular CDMA is limited by interference. When all of the users occupy the same bandwidth and have the same fidelity requirements, e.g. voice, an equation has been derived for the maximum number of users. In this paper, we expand on this analysis for a homogeneous set of users and include different classes of users defined by their bandwidths and fidelity requirements. This allows, for example, mixing data users and voice users in a cellular system. Plots illustrating the tradeoffs between the number of users in each class are shown.

Historically, the Computer Science Department taught a series of service courses for non-majors. These courses were intended primarily for students in the humanities and social sciences, business, natural sciences, and engineering. In 1993, computer science was merged into the Department of Electrical and Computer Engineering, immediately raising the question of whether or not the School of Engineering should be in the business of offering service courses to nonengineering students. It was finally decided to allow the new Electrical Engineering and Computer Science Department to offer the service courses with the promise of a major overhaul of the content, organization, and laboratory facilities. A faculty member was asked to be responsible for the courses. The graduate teaching assistants who teach the courses were organized, trained, and ones with poor teaching records were dismissed. New computing equipment was purchased with engineering equipment fee money. Course curricula were completely revamped. The results of the experiment have been most gratifying. Enrollment demand has increased even though the courses are now "engineering" courses. Feedback from the approximately 1800 students who take the courses annually borders on rave reviews, a considerable change from the past. This paper discusses our experience in more detail.

A test chip has been designed and fabricated for the evaluation of surface-diffusion phenomena. It allows the confirmation of the correct sample cross-section bevel angle and orientation for scanning electron microscope (SEM) inspection of step coverage. These features eliminate ambiguities that may otherwise arise in the interpretation of the SEM images. The chip design provides arrays of vias with multiple combinations of size and spacing to enable characterization and modeling of the aluminum planarization phenomena for a full range of deposition parameters. It also incorporates electrically readable test structures that allow relating the SEM images of step coverage to corresponding electrical properties, such as electromigration, of the deposited metal. The overall objective is to permit the selection of deposition parameters that simultaneously produce visually acceptable step-coverage images and optimized electrical properties of the film. >

The delay, throughput and capacity analysis of a DS-CDMA packet cellular network is carried out in this paper. A mix of data and voice user classes is assumed. Error free communication is required for the data users but is not delay sensitive while voice applications allow some degree of error but is delay sensitive. The QoS for data users is therefore the delay while for voice it is the bit error rate (BER).

Wireless communication channels such as mobile radio or indoor wireless channels suffer from a number of impairments including signal fading which causes severe performance degradation. The adverse effects of fading can be mitigated by employing space (spaced antennas) diversity techniques at the mobile and/or at the base station. This paper derives the bit-error-rate equations for BPSK using maximal-ratio-combining with correlated fading as an explicit function of the bit energy-to-noise density ratio, the signal envelope cross correlation coefficient, and the diversity order. The special case of dual diversity is studied in detail. In addition, results from the literature for predicting the signal cross-correlation between antennas can be used with the expressions derived to predict BER performance as a function of antenna separation.

The received signal amplitude of an indoor wireless channel is generally modeled as Rayleigh or Rician fading depending on the situation. In addition to these, other fading models including the Gilbert, two-state analog, and log-normal are used for fading channels in general. Bultitude [1987] found that his measurements of several indoor channels best fit the Rician model. The present authors describe a two-state Rician fading model that better matches Bultitude's data. For DPSK, the bit-error-rate performance of the two-state Rician model is worse than the pure Rician model by about 8 dB.

The Cassini Program is the last of the large interplanetary spacecraft missions. The Integration Test Laboratory (ITL) at the Jet Propulsion Laboratory (JPL) is part of the Cassini Program. This laboratory includes the Attitude and Articulation Control Subsystem (AACS) testbed. This environment was used to not only verify and validate the AACS but was also used to develop advanced concepts and ideas for use in future testbed environments. The concepts developed for the AACS testbed included the use of multiple computers, real-time data collection and real-time display. Internet access and the incorporation of commercially available components. These concepts resulted in improved simulation fidelity, repeatable operation and reduced future operational costs. This paper focuses on a description of the testbed, lessons learned, the innovations used and future directions that will substantially reduce future testbed costs.

The duration of excretion of Toxocara vitulorum larvae in the milk of buffalo cows determines the optimum time for treating calves. Studies on 10 cows showed that a few larvae occur in the colostrum of some cows before the calf has suckled, but most are present from the day after calving and for a further five days. From day 9 onwards, very few larvae were found in the milk. The total number of larvae found was comparable with the number of adult parasites collected from the calves of cows with similar histories. The larvae were 1254 +/- 60 microns long and 36 +/- 6.7 microns in diameter at the ventriculus, figures which are substantially different from some published results.

The plasma levels of GLDH and the dynamics of development of the numbers of surface lesions on livers, and numbers of parasites, within two to three weeks of a challenge infection, indicated that the major component of the high resistance of Indonesian thin tail (ITT) sheep against Fasciola gigantica was acquired, and acted against juvenile parasites. Few parasites reached the livers of ITT (exposed) sheep, but many had been inhibited, probably in the wall of the jejunum. ITT (naive) sheep showed some resistance, compared with control Merino sheep, by three weeks after infection. Manifestation of the resistance of ITT (exposed) sheep was suppressed by administration of the immunosuppressant, dexamethasone. Killing of parasites in ITT sheep appeared to have ceased by 21 to 28 days after infection. The basis of the acquired resistance was deemed to be an exceptional immunological capacity of ITT sheep responding to an antigen, or an immunological suppressant, peculiar to F. gigantica. That molecule, produced by juvenile parasites, warrants further study as a candidate for a vaccine.

Approaches to the control of fasciolosis in ruminants are compared for developed countries, and for developing countries with particular reference to regions growing irrigated rice. In all environments problem definition and investigation are based on one or more of observation, abattoir surveys, faecal egg counts, tracer animals and snail studies. In developed countries each husbandman grazes a large number of animals, controls access to pasture and water, and markets high value products. Strategic and tactical treatments control fasciolosis in these circumstances and will continue to do so while anthelmintics remain effective. In many developing countries subsistence families possess small numbers of animals, feed and water sources are shared by many families, and the products are mainly draft power, fertiliser and meat for local consumption. Consequently the agricultural cycle, and the life cycles of the parasite and intermediate host, are closely interrelated and there is some scope for controlling infection by modifying husbandry practices. Anthelmintics are not affordable. Recent observations of a major fasciola resistance gene with substantial dominance, in Indonesian Thin Tail sheep infected with Fasciola gigantica, suggest that parasite control by breed substitution, or cross-breeding and selection, is feasible. Such control would be inexpensive to implement, and sustainable.

The egg production of Toxocara vitulorum in Asian buffalo has been studied. Eggs were first present in the faeces of calves when they were 22.3 ± 1.6 days old. In calves treated with pyrantel when 3 days old, the age at first patency was extended by 3.5 days indicating that there was no pre-natal transmission. Calves on only half the milk of the cow had a significantly longer prepatent period of 27.7 ± 2.2 days. The peak egg output occurred in calves 35.7 ± 2.6 days old and had a duration of 5.5 ± 2.5 days with 98 000 ± 63 700 eggs g −1 of faeces. The duration of the patent period was 35 ± 12 days. The average lengths of populations of mature female parasites from different hosts at the time of peak egg output or older, ranged from 15.0 to 31.0 cm and was correlated with those of the males in the same populations (10.6–20.4 cm). The size of females was not affected by intraspecific competition. The proportion of males in the populations was 0.39 ± 0.11. The egg output per female per day at the peak was 110 000 ± 58 000 and was correlated with the size of the females at autopsy, but the egg output per female per day at the time of autopsy was lower and was not correlated, so it was concluded that the drop in egg counts was the result of reduced fecundity. The fertility of the eggs from faeces was > 92% throughout. The drop in egg production was not affected by administration of dexamethasone or by restricting calves to a milk diet, so it is suggested that the drop may be due to an ageing process in the parasite. The importance of the age of the calf in determining the pathogenic significance of egg counts, and in epidemiological studies, is emphasised. Reports of substantially different prepatent and patent periods are discussed.

An economic evaluation to compare the costs of care and likely outcome for patients treated with alpha-interferon for chronic active hepatitis B and C was performed. As complete prospective data are not available, we have made comparisons between two cohorts of 100 hypothetical patients. Treatment of chronic hepatitis B would be with alpha-interferon at an average dose of 9 million units three times per week for 16 weeks. Chronic active hepatitis C treatment is based on a dose of 3 million units three times weekly for a total of 6 months. In untreated patients with chronic active hepatitis B or C, the risk of developing cirrhosis is considered to be 10-20% in a 10-year period. Patterns of good practice are costed using typical costs of patients in our institution. These costs are aggregated using the probabilities of morbidity and mortality, from therapeutic and epidemiological studies, for patients developing cirrhosis. A sensitivity analysis has been applied to the results. If we assume a latency period of 10 years, the costs of a successfully treated patient with both hepatitis B and C will be recouped. For hepatitis C, benefits are apparent when social costs are added, the price of alpha-interferon is reduced by 10% and the response rate raised by 20%. Nevertheless, if morbidity effects and costs to patients are included, the advantages of treatment are more apparent, with potential savings in both chronic hepatitis B and C. The model we have developed can be adapted as firmer evidence becomes available.

Fixation and staining characteristics were studied for mast cells recovered by bronchoalveolar lavage from 67 patients being investigated for lung disease. The number of toluidine blue stained mast cells in formaldehyde-fixed cytocentrifuge preparations was consistently less than in specimens fixed in Carnoy’s solution, though the counts were highly dependent on the period of fixation or staining. The cellular histamine content closely correlated with total mast cell numbers in bronchoalveolar lavage fluid, but was not related to the relative proportions of mast cells which were sensitive or resistant to formaldehyde fixation when using a standard protocol. Compared with normal subjects, the numbers of formaldehyde-sensitive mast cells were significantly elevated in patients with bronchial carcinoma, sarcoidosis, extrinsic allergic alveolitis, cryptogenic fibrosing alveolitis, and mycobacterial infection and were particularly high in the cases of interstitial lung disease. An even greater increase in numbers of formaldehyde-resistant mast cells was observed in the patients with sarcoidosis and extrinsic allergic alveolitis. The associations of these mast cell subsets with disease may reflect relationships between the expansion of the formaldehyde-sensitive population and lymphocyte infiltration and between proliferation of formaldehyde-resistant mast cells and tissue fibrosis.