Showing papers by "Monash University published in 1992"

Kelly West Lecture 1991 Challenges in Diabetes Epidemiology—From West to the Rest

Abstract: The application of epidemiology to the study of non-insulin-dependent diabetes mellitus (NIDDM) is providing new insights into many aspects of this major public-health problem, including its natural history, prevalence, incidence, morbidity, and mortality in diverse populations around the globe. The main impetus came from the late Kelly West9s book Epidemiology of Diabetes and its Vascular Lesions . These studies are providing direction for research into the possible moleculardefect or defects and biochemical mechanism or mechanisms underlying NIDDM and important information on the extrinsic (social, cultural, environmental) risk determinants. Studies have highlighted the importance of regional adipose tissue distribution, particularly upper-body obesity, and physical inactivity in enhancing risk of NIDDM. These findings have important implications for the primary prevention of NIDDM, particularly in populations with increased genetic susceptibility such as Polynesians, Micronesians, American and Asian Indians, Mexican Americans, and Australian aborigines.

A cointegration analysis of treasury bill yields

Abstract: This paper shows that yields to maturity of U.S. Treasury bills are cointegrated, and that during periods when the Federal Reserve specifically targeted short-term interest rates, the spreads between yields of different maturity define the cointegrating vectors. This cointegrating relationship implies that a single non-stationary common factor underlies the time series behavior of each yield to maturity and that risk premia are stationary. An error correction model which uses spreads as the error correction terms is unstable over the Federal Reserve's policy regime changes, but a model using post 1982 data is stable and is shown to be useful for forecasting changes in yields.

4-phase sequences with near-optimum correlation properties

Abstract: Two families of four-phase sequences are constructed using irreducible polynomials over Z/sub 4/. Family A has period L=2/sup r/-1. size L+2. and maximum nontrivial correlation magnitude C/sub max/ >

Age related changes in follicle stimulating hormone, luteinizing hormone, oestradiol and immunoreactive inhibin in women of reproductive age

Abstract: Objective In women over the age of 45 years with continuing regular menstrual cycles, follicular phase FSH levels rise without an accompanying change in LH. We determined the effect of increasing age in women with regular cycles on the serum levels of FSH, LH, immunoreactive inhibin, progesterone and oestradiol. Design Single blood samples were taken during the early follicular phase (days 4-7) and again in the midluteal phase (3-12 days before the next menses) of the menstrual cycle. Patients Regularly cycling women aged 21-49 years participated in the study (and were grouped into four groups: 20-29, 30-39, 40-44 and 45-49 years in the follicular phase and three groups: 20-29, 30-39 and 40-49 years in the luteal phase. Measurements Serum levels of FSH, LH, oestradiol, progesterone and immunoreactive inhibin were measured from the blood samples obtained. Results Follicular phase Mean follicular phase levels of immunoreactive inhibin were significantly lower in the 45-49 year age group (P less than 0.05) than in the younger age groups (128 U/l in the 45-49 year age group vs 239, 235 and 207 U/l in the 20-29, 30-39, 40-44 year age groups respectively), while mean FSH levels were significantly higher in the 45-49 year age group (P less than 0.05, 13.0 IU/l in the 45-49, 4.9, 5.5 and 5.2 IU/l in the 20-29, 30-39 and 40-44 year age groups respectively). Mean oestradiol levels in the 45-49 year age group were significantly lower only when compared to age group 30-39 years (P less than 0.05, 130 vs 210 pmol/l). There was no significant difference in oestradiol levels between the 45-49 year age group and the 20-29 and 40-44 year age groups. LH levels did not differ significantly across age groups. There was also a significant negative correlation between serum immunoreactive inhibin and FSH (r = -0.45, P less than 0.05) and between oestradiol and FSH (r = -0.35, P less than 0.05). There was a significant negative relationship between immunoreactive inhibin and age (r = -0.46, P less than 0.05). For every 10-year increase in age, average immunoreactive inhibin decreased by an estimated 49.3 U/l. As age increased, average FSH levels exhibited a two-phase linear increase with the change-point estimated at 42.97 (1.42) (estimate (SE)) years. Prior to 42.97 years, FSH barely changed; after 42.97 years there was a significant (P less than 0.05) increase in FSH as age increased. Oestradiol levels did not change significantly until an estimated 37.9 years of age, but then decreased significantly (P less than 0.05) with increasing age. Luteal phase Levels of FSH, LH, serum immunoreactive inhibin, oestradiol and progesterone fell slowly with increasing age. There was a significant correlation between serum immunoreactive inhibin with progesterone (r = 0.41, P less than 0.05) but there was no correlation between serum immunoreactive inhibin LH or FSH. Conclusion The results are consistent with a role for serum immunoreactive inhibin, in addition to oestradiol, in the regulation of FSH during the follicular phase of the menstrual cycle as a function of increasing age. This is postulated to reflect diminished folliculogenesis as age progresses with the known decline in the numbers of primordial follicles in the ovary as the menopause approaches.

Offset curves and surfaces : a brief survey

Abstract: The designing of offset curves and surfaces is an essential task in many industrial applications such as the generation of tool-path geometry in numerical-control machining and robot-path planning. The paper discusses problems that are encountered in the designing of offsets, gives a brief survey of existing techniques, and suggests some directions for future research.

Intention, Context, and Safe Sex: Australian Adolescents' Responses to AIDS

Abstract: This study examined the applicability to condom use of Ajzen and Madden's (1986) theory of planned behavior by examining the predictors of intention to use a condom and actual condom use in a specific sexual situation. In a sample of 144 sexually active heterosexual males and females, limited support was found for the model. Intentions to use a condom immediately before a particular sexual encounter, and those assessed some time prior to this encounter were found to have direct and positive effects on condom use. In addition, perceptions of the disadvantages of condoms (a measure of attitudes to condoms in general) had direct negative effects on condom use and, together with perceptions of the advantage of condoms, also had indirect effects on condom use via prior intention. A number of the postulated predictors of safe sexual practice related neither to intentions nor behavior. The contextual variables of sexual arousal, condom availability, and degree of communication with a sexual partner all influenced condom use. Discussion centered on first, differences in the predictive ability of the model when compared to other studies of planned behavior, and second, the factors limiting the relationship between intention and behavior when the behavior in question is not under complete, volitional control.

Submarine volcanism; eruption styles, products, and relevance to understanding the host-rock successions to volcanic-hosted massive sulfide deposits

Abstract: The increasing hydrostatic pressure of the water column with increasing water depth in subaqueous environments limits the ability of superheated volatiles to expand instantaneously against the ambient pressure. Explosive submarine eruptions are only likely in water depths less than 1 km, and generally less than 500 m, thus refuting models of highly explosive, very deep water calderas popularly proposed as the host volcanic centers for the kuroko volcanic-hosted massive sulfide (VHMS) deposits of Japan. Large volumes of blocky breccias can be produced by quench fragmentation during submarine lava eruptions, and such deposits may have been mistaken for pyroclastic deposits in many cases in the past. Pyroclastic debris may occur in the host-rock successions of some VHMS deposits and may even be very voluminous. However, facies characteristics and theoretical constraints indicate that these are usually the products of mass-flow deposition from shallow-water or basin margin volcanic centers. The maximum water depths for submarine explosive eruptions coincide approximately with the minimum pressures and water depths required to prevent boiling of mineralizing hydrothermal fluids in the stockwork before the fluids reach the sea floor. The key elements in evaluating the prospectivity of ancient volcanic successions for VHMS deposits appear to be deep-water sediments and lavas or shallow intrusions in an extensional basin setting. Pyroclastic debris, in many cases at least, appears to be an accidental, externally introduced component. There is little evidence that explosive submarine calderas are essential as host volcanic centers to VHMS deposits.

The concept of recovery and secondary prevention in psychotic disorders.

Abstract: The concept of recovery is embedded in the current classification of functional psychosis, an unfortunate fact which has obscured important therapeutic and preventive opportunities for patients and their relatives. A range of theoretical perspectives is reviewed which could be drawn upon to extend research, and develop and evaluate new forms of intervention in this area. The major tasks facing patients and their families at different stages of illness are described, and a series of principles is then proposed to guide the clinical care of recovering psychotic patients.

Risk factors for cardiovascular disease in chronic spinal cord injury patients.

Abstract: To establish whether the reported increased cardiovascular (CV) morbidity in spinal cord injury (SCI) patients is due to increased levels of established CV risk factors, we assessed overall CV risk in 102 consecutive patients aged 25-64 by calculation of a 'risk factor score' (RFS) derived from the MRFIT study (age, diastolic blood pressure (DBP), total cholesterol (TC) level, cigarettes/day, sex), obtaining a percentile position amongst an age and sex matched peer group from the 1983 Australian Risk Factor Prevalence Study. Chronic SCI patients had a very low overall percentile position of risk of 26.03 + 15.06 (mean +/- S.D.) and those patients with SCI for greater than 10 years had only a slightly higher risk position of 33.16 +/- 29.66. The low relative risk in SCI patients was due mainly to significantly lower DBP levels (67 +/- 13 mm hg), as TC levels (5.38 +/- 1.60 mmol/L) and cigarette consumption (31% smokers, mode 11-20/day) were similar to the control population (83 +/- 12 mmHg, 5.68 +/- 1.2 mmol/L, 28% smokers, mode 11-20/day, respectively). As other known risk factors such as lipoprotein cholesterol fractions were not included in the RFS index, these were measured in 327 consecutive SCI patients. HDL cholesterol levels, which are negatively correlated with CV risk, were significantly lower in SCI patients (1.12 +/- 0.30 mmol/L) compared to controls (1.35 +/- 0.35 mmol/L) and those patients more than 10 years post SCI had still lower levels (1.02 +/- 0.40). These data suggest that the reported increased incidence of CV disease in SCI patients is unexplained by increases in BP, TC or smoking. However, low HDL levels may contribute to CV risk and the role of other risk factors such as increased vascular reactivity remain to be established.

Time Stationarity of Systematic Risk: Some Australian Evidence

Abstract: While the evidence on time-varying systematic risk of U.S. assets is well documented in the literature, little work has been conducted in the Australian equity market. This paper intends to fill this gap in the literature by employing an alternative testing procedure to those used in previous studies. Moreover, a new methodology of determining the p-value of a test statistic is applied. The results of our study suggest that there is evidence of time-varying systematic risk for both individual assets and portfolios in Australia. * Department of Accounting and Finance, Monash University. ** Department of Econometrics, Monash University. The authors wish to thank Tim Brailsford, Robert Brooks, Grant Hillier, Max King and the participants at a Monash University Department of Econometrics seminar for constructive comments on earlier versions of this paper._ The second author is grateful for the financial support of a Monash Graduate Scholarship. All deficiencies in the paper are the sole responsibility of the authors.

Mandatory bicycle helmet use: experience in Victoria, Australia

Abstract: On July 1, 1990, the legislation requiring wearing of an approved bicycle (safety) helmet by all pedal cyclists, unless exempted, came into effect in Victoria, Australia. The paper describes the more important activities which paved the way for this initiative and presents some preliminary information about the effect of the legislation on wearing rates and head injuries. Since 1980 there has been promotion of helmet use through bicycle education in schools, mass media publicity, support by professional organizations and community groups, bulk purchase schemes, and government rebates for helmet purchases. The Australian Standard for bicycle safety helmets has also been changed to meet community demands for lighter helmets with more provision for ventilation. There has been a steady increase in voluntary helmet use in Melbourne from 1983 to March 1990, as follows: 5% to 70% in primary school children; 2% to 20% in secondary students; and 27% to 40% in adults. In the period after the legislation, with relatively little enforcement, these three groups have shown substantial increases in helmet use rates, rising to 70-90% in most cases. Preliminary data show that the numbers of bicyclists with a head injury have dropped in the period since the legislation came into effect. The possible contributions to this reduction, of less bicycle use and lower risk of head injury in an accident, are discussed.

Foreign Exchange Risk Management Practices and Products used by Australian Firms

Abstract: This industry-wide, cross-sectional study concentrates on recent foreign exchange risk management practice and product usage of large Australian-based firms. Results are discussed from an empirical field study of seventy-two firms operating in Australia. Based on a statistical analysis of five firm-specific variables with six management-practice variables, conclusions are drawn on the foreign exchange risk management practices and financial product usage of firms operating in Australia.© 1993 JIBS. Journal of International Business Studies (1993) 24, 557–573 (This abstract was borrowed from another version of this item.)

The general relationship between regular-sampled pulse-width-modulation and space vector modulation for hard switched converters

Abstract: Regular sampled pulse width modulation and space vector modulation are often presented as two alternative ways to modulate a hard switched converter system. In the present work, a mathematical relationship between these two types of modulating strategies is established, using reduced forms of general AC-AC matrix converter modulation theory. The resultant modulation strategy is shown to be identical to previously reported space vector solutions, which are known to achieve minimum harmonics for both voltage source and current source inverters. This relationship is then extended to be applied to an AC-AC matrix converter, to create a simple space vector modulation algorithm for a matrix converter which can be easily implemented for real-time computation in an online control system. >

The behavior of tin in granitoid magmas

Abstract: The spatial and temporal relationship between tin mineralization and granitoid rocks is well documented. A great deal of work, including mineralogic, geochemical, fluid inclusion, and stable and radiogenic isotope studies, has been undertaken on numerous cassiterite-bearing deposits in order to resolve the problem of their genesis. Despite this exhaustive research, the association between tin mineralization and felsic magmatism remains poorly understood. Experimental investigations into the behavior of tin in melts have been undertaken to evaluate the physical and chemical constraints on the mobilization of tin from magmas.The concentrations of tin in equilibrium with SnO 2 -saturated, synthetic, peraluminous granitoid melts have been examined as a function of temperature (700 degrees -800 degrees C), pressure (2.0-3.0 kbars), oxygen fugacity (from 0.7 log units more reduced to 1.5 log units more oxidized than the quartz-fayalite-magnetite buffer) and granitoid composition (haplogranite, K feldspar-quartz, and albite-quartz). Melts were found to contain between 400 and 2,500 ppm tin. The solvent capacity of the granitoid melts is increased by decreasing oxygen fugacity and by increasing the alkali/alkali + aluminum ratio (ALK/AL), i.e., K 2 O + Na 2 O/K 2 O + Na 2 O + Al 2 O 3 (Naski and Hess, 1985) and the Na/K ratio of a melt. Changes in temperature or pressure do not exert a significant influence over the concentration of tin in melts. Nuclear gamma resonance analysis of haplogranite glasses indicates that both Sn (super +2) (sub (melt)) and Sn (super +4) (sub (melt)) are stable over the range of oxygen fugacities typically attending the crystallization of granitoids. The coordination and likely speciation of Sn (super +2) and Sn (super +4) in melts is discussed. The basicity of a melt (activity of free oxygens, a (sub O (super -2) ) ), which is often strongly correlated with the ALK/AL of a melt (cf. Hess, 1980; Mysen, 1986), is likely to be very important in influencing the acidity of a coexisting fluid phase. Peraluminous melts (low ALK/AL) will generally display low melt basicities and therefore will buffer the acidity of a magmatic aqueous phase at far higher values than a peralkaline melt.These results indicate that granitoid melts derived from common crustal sources will be markedly SnO 2 undersaturated. Consequently, alternative processes must be sought to explain the elevated tin concentrations in many plutons. The complex distribution of tin in any batholith will be largely controlled by the redox conditions accompanying the crystallization of assemblages capable of accommodating tin and the physical processes which can influence their distribution.

Monitoring chemical exposure using breast milk : a methodological review

Abstract: Retrospective exposure assessments are often a major weakness in environmental epidemiologic studies. Many environmentally important chemicals are persistent lipophilic compounds which partition into fat and breast milk. The analysis of these chemicals in breast milk provides a noninvasive means of collecting large volumes of a biologic fluid that correlates well with body burden. This may provide an integrated measure of cumulative absorption over several years which can be used to assess exposure in several different epidemiologic study designs. However, consideration of toxicokinetic principles in the study design is important in order to allow for maternal and other factors unrelated to exposure which may influence breast milk concentrations. These factors include maternal age, parity, maternal body weight, time of sampling during the lactation period, and fat content of the breast milk. Failure to use standardized entrance criteria and to allow for the above factors in the analysis and interpretation of the study results may lead to invalid conclusions regarding past exposures. Allowance must also be made for the restrictions on the sampling frame available in any epidemiologic study using breast milk analysis. Published studies to date often have had several methodological deficiencies. With the introduction of biologic specimen banks, breast milk collection and analysis should play an important role in future epidemiologic studies, especially those investigating health outcomes in infants.

Detachment faults:Evidence for a low-angle origin

Abstract: The origin of low-angle normal faults or detachment faults mantling metamorphic core complexes in the southwestern United States remains controversial. If [sigma][sub 1] is vertical during extension, the formation of, or even slip along, such low-angle normal faults is mechanically implausible. No records exist of earthquakes on low-angle normal faults in areas currently undergoing continental extension, except from an area of actively forming core complexes in the Solomon Sea, Papua New Guinea. In light of such geophysical and mechanical arguments, W.R. Buck and B. Wernicke and G.J. Axen proposed models in which detachment faults originate as high-angle normal faults, but rotate to low angles and become inactive as extension proceeds. These models are inconsistent with critical field relations in several core complexes. The Rawhide fault, an areally extensive detachment fault in western Arizona, propagated at close to its present subhorizontal orientation late in the Tertiary extension of the region. Neither the Wernicke and Axen nor Buck models predict such behavior; in fact, both models preclude the operation of low-angle normal faults. The authors recommend that alternative explanations or modifications of existing models are needed to explain the evidence that detachment faults form and operate with gentle dips.

Reconstruction of the tectonic, volcanic, and sedimentary setting of strongly deformed Zn-Cu massive sulfide deposits at Benambra, Victoria

Abstract: The Wilga and Currawong massive sulfide deposits at Benambra are hosted by a strongly deformed, Upper Silurian rhyolite-dacite-andesite-basalt-sediment succession, dominated by silicic volcanics and sedimentary rocks. This host succession developed in an ensialic back-arc or intra-arc basin of limited extensional origin on the active Gondwana continental margin. Strong deformation is related to compressional and transcurrent crustal movements during closing of the depositional basin at the end of the Silurian and to subsequent steep faulting.The massive sulfide deposits are essentially synvolcanic because (1) they have the same three generations of tectonic structures and the same intensity of deformation as their host rocks, suggesting that the ores predate the earliest compressional deformation, (2) the ores are constrained to a Late Silurian age similar to their host rocks because both the host rocks and this earliest deformation are Late Silurian in age, (3) there is a tight stratigraphic control on the location of the massive sulfides, and (4) the stratigraphy, depositional setting, and alteration are similar to many other less-deformed volcanic-associated massive sulfide districts.Deformation and alteration inhibit detailed stratigraphic correlation and modify rock textures, but do not destroy facies relationships, which allow sedimentological and volcanological interpretation. Sedimentary facies associations indicate that mineralization occurred in the basin center after fault-controlled subsidence from a mixed subaerial and subaqueous environment with active rhyolitic volcanism, through a marine shelf environment with mixed limestone-volcaniclastic sedimentation, to a moderate- to deep-water environment with mudstone and turbidite sedimentation and rhyolitic to basaltic volcanism.Juvenile elastic and nonelastic volcanic rocks are closely associated, subequal in volume, and comprise 50 to 70 percent of the volcano-sedimentary sequence. Evaluation of fragmentation and emplacement processes indicates that the juvenile volcaniclastics are mainly in situ, resedimented and intrusive hyaloclastites, rather than pyroelastics. Classification of primary contact relationships of the volcanics into passive, slightly disruptive and highly disruptive types, and the internal facies organization of the volcanic units, indicate that the volcanics form extrusive domes, extrusive tabular flows, partially emergent cryptodomes and sills, and entirely intrusive sills. Shallow sills and cryptodomes emplaced into wet subsea-floor sediments are texturally similar to, but more abundant than, lavas in the environment of mineralization. These shallow intrusions are distinguished by disruptive upper contacts including sediment-veined and sediment-matrix hyaloclastite. Their recognition is critical because the mineralized stratigraphic interval can only be correlated using volcanics and sediments emplaced on the sea floor. Based on extrusive units, the massive sulfides occur within 100 m above the last major extrusive rhyolites and within 50 m below the first major basalt lava.Integrating the tectonic, structural, sedimentological, and volcanological data shows that the massive sulfides formed in siltstone, in the proximal (near-vent) facies association of a low profile, mainly nonexplosive, moderate to deep-water submarine volcano composed of turbiditic sediments interleaved with numerous rhyolitic to basaltic sills, lavas, and associated hyaloclastites. The ores can be related in space and time to the advanced stage of extension and subsidence in a continental margin incipient rift, when relatively deep-marine conditions were attained, generation of voluminous rhyolitic crustal melts waned, and basaltic magma started to penetrate up deep extensional faults to the sea floor. The spatial association of the last rhyolite extrusions, the massive sulfides, and the first basalt extrusions, suggests that these rocks are genetically related and that all were fed via the same extensional fault system. This setting of silicic volcanic-associated massive sulfides at Benambra provides a model for the many deposits related to mainly nonexplosive volcanism and an alternative to the recently popular submarine pyroclastic caldera model.

Finite-state models in the alignment of macromolecules.

Abstract: Minimum message length encoding is a technique of inductive inference with theoretical and practical advantages. It allows the posterior odds-ratio of two theories or hypotheses to be calculated. Here it is applied to problems of aligning or relating two strings, in particular two biological macromolecules. We compare the r-theory, that the strings are related, with the null-theory, that they are not related. If they are related, the probabilities of the various alignments can be calculated. This is done for one-, three-, and five-state models of relation or mutation. These correspond to linear and piecewise linear cost functions on runs of insertions and deletions. We describe how to estimate parameters of a model. The validity of a model is itself an hypothesis and can be objectively tested. This is done on real DNA strings and on artificial data. The tests on artificial data indicate limits on what can be inferred in various situations. The tests on real DNA support either the three- or five-state models over the one-state model. Finally, a fast, approximate minimum message length string comparison algorithm is described.

A new disease-related mutation for mitochondrial encephalopathy lactic acidosis and strokelike episodes (MELAS) syndrome affects the ND4 subunit of the respiratory complex I.

Abstract: The molecular lesions in two patients exhibiting classical clinical manifestations of MELAS (mitochondrial encephalopathy, lactic acidosis, and strokelike episodes) syndrome have been investigated A recently reported disease-related A----G base substitution at nt 3243 of the mtDNA, in the DHU loop of tRNA(Leu), was detected by restriction-enzyme analysis of the relevant PCR-amplified segment of the mtDNA of one patient but was not observed, by either restriction-enzyme analysis or nucleotide sequencing, in the other To define the molecular lesion in the patient who does not have the A----G base substitution at nt 3243, the total mitochondrial genome of the patient has been sequenced An A----G base substitution at nt 11084, leading to a Thr-to-Ala amino acid replacement in the ND4 subunit of the respiratory complex I, is suggested to be a disease-related mutation

Structural and magnetic properties of ferrihydrite

Abstract: Fe MSssbauer spectra of two synthetic samples of ferrihydrite, recorded at 4.2 K in applied fields of up to 9 T, have been analysed by a mean-field model. The samples exhibit two and six X-ray diffraction peaks. It is shown that only one ferric ion site is present in the mineral, and that in this site the ions are octahedrally coordinated. The spectra show the presence of different magnetic states: ferri- magnetism in two-line ferrihydrite, and antiferromagnetism in six-line ferrihydrite. The ferrimagnetism in two-line ferrihydrite is analysed in terms of random fluctuations arising from the small numbers of ferric ions per particle, and it is shown that the different magnetic states may arise purely as a result of these fluctuations.

Duty and Desolation

Abstract: This is a paper about two philosophers who wrote to each other. One is famous; the other is not. It is about two practical standpoints, the strategic and the human, and what the famous philosopher said of them. And it is about friendship and deception, duty and despair. That is enough by way of preamble.

Quality management practices in Australian industry

Abstract: Over the past few years a dramatic shift towards strategic quality management has been witnessed in some of Australia's leading companies. This dramatic shift in perspective has elicited senior management interest and involvement; linked quality with profitability and seen the inclusion of quality in strategic planning. This paper presents the results of an investigation on the quality management practices of a number of Australian companies with a known commitment to quality. It addresses general management practices, human resource issues, quality control practices and quality program evaluation.

A comparison of diagnostic tests to determine Helicobacter pylori infection.

Abstract: Twenty-five Helicobacter pylori positive and 25 H. pylori negative subjects as defined by culture and phase contrast microscopy of antral biopsy specimens obtained from routine upper endoscopy were studied. Antral biopsies were examined by rapid urease test, phase contrast microscopy, culture and histology. Venous blood was tested for H. pylori specific IgG antibodies by an ELISA technique. Within 7 days of endoscopy the patients also had a [14C]-urea breath test. The sensitivity and specificity of the rapid urease test was 92%, the breath test 96% and 100%, histopathology 96% and 91% and serology 96% and 88%, respectively. The [14C]-urea breath test performed over 1 h with sampling of subjects at 0, 0.5 and 1 h was an accurate and reliable method. Results expressed as counts per minute of the expired 14CO2 proved to be a simple method of assessing H. pylori status. A significant correlation between severity of histological antral gastritis and the amount of 14CO2 expired was observed. This study has shown that the non-invasive 14C-urea breath test and serology are highly sensitive and specific for the diagnosis of H. pylori infection.