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We present the analysis of an X-ray fluorescence (XRF) observation of the western part of Oceanus Procellarum on the Moon’s nearside made by the Chandrayaan-1 X-ray Spectrometer on 10th February 2009. Through forward modelling of the X-ray spectra, we provide estimates of the MgO/SiO2 and Al2O3/SiO2 ratios for seven regions along the flare’s ground track. These results are combined with FeO and TiO2 contents derived from Clementine multispectral reflectance data in order to investigate the compositional diversity of this region of the Moon. The ground track observed consists mainly of low-Ti basaltic units, and the XRF data are largely consistent with this expectation. However, we obtain higher Al2O3/SiO2 ratios for these units than for most basalts in the Apollo sample collection. The widest compositional variation between the different lava flows is in wt% FeO content. A footprint that occurs in a predominantly highland region, immediately to the north of Oceanus Procellarum, has a composition that is consistent with mixing between low-Ti mare basaltic and more feldspathic regoliths. In contrast to some previous studies, we find no evidence for systematic differences in surface composition, as determined through X-ray and gamma-ray spectroscopy techniques.

We have conducted laboratory experiments as an analogue to planetary XRF (X-ray fluorescence) missions in order to investigate the role of changing incidence (and phase) angle geometry and sample grain-size on the intensity of XRF from regolith-like samples. Our data provide evidence of a grain-size effect, where XRF line intensity decreases with increasing sample grain-size, as well as an almost ubiquitous increase in XRF line intensity above incidence angles of ∼60°. Data from a lunar regolith simulant are also used to test the accuracy of an XRF abundance algorithm developed at the Rutherford Appleton Laboratory (RAL), which is used to estimate the major element abundance of the lunar surface from Chandrayaan-1 X-ray Spectrometer (C1XS) XRF data. In ideal situations (i.e., when the input spectrum is well defined and the XRF spectrum has a sufficient signal to noise ratio) the algorithm can recover a known rock composition to within 1.0 elemental wt% (1 σ ).

The Chandrayaan-1 X-ray spectrometer (C1XS) experiment on the Chandrayaan-1 mission was designed to carry out spectroscopic observations in the 1–10 keV range for deriving lunar chemistry. We present results from the ground calibration of the Swept Charge Devices (SCDs) on C1XS at the RESIK X-ray beam facility at Rutherford Appleton Laboratory, Chilton, UK. The spectral redistribution function of the SCDs are determined in the energy range from 2.3–8 keV using discrete line energies from a monochromatic X-ray beam. The detection efficiency of the SCDs are determined relative to a reference Si-PIN detector. The Si-PIN detector itself has been calibrated at the beamlines of the synchrotron facility at PTB/BESSY II. A non-Gaussian response matrix which includes probability for partial absorption events in the SCD is constructed using instrument parameters obtained from ground calibration. The calibration spectra from the 55 Fe radioactive isotopes obtained from C1XS while in the lunar orbit, are used to validate the response matrix derived on ground.

The Chandrayaan-1 XSM ground calibrations are introduced. The aim of these calibrations was to characterize the performance of XSM, which enables a reliable spectral analysis with the solar X-ray data. The calibrations followed an improved procedure based on our experience from the SMART-1 XSM. The most important tasks in the calibrations were determination of the energy resolution as a function of the photon energy and mapping of the detector sensitivity over the FoV (Field of View) of the sensor. The FoV map was needed to determine the obscuration factor corresponding to various pointings with respect to the Sun. We made also a sensitivity comparison test between the Chandrayaan-1 XSM FM (Flight Model) and SMART-1 XSM FS (Flight Spare). The aim of this test was to link the new XSM performance to a performance of an already known and tested former instrument. We also performed a simple test to determine the pile up performance, and one specific test tailored for the operation of the new version of XSM. Also the first experiences on the in-flight operation are briefly described.

The operation, performance, and in-flight calibrations of the X-ray Solar Monitor (XSM) on-board ESA's SMART-1 mission to the Moon are presented. The basic method of deriving the response and effective area of the XSM is described. The evolution of the energy resolution as a function of time is studied, and sample data of high quality broadband solar flare spectra including highly ionized Fe-lines are also presented.

著者人数：48名, Accepted: 2002-12-31, 資料番号: SA1002070000

The purpose of the D-CIXS (Demonstration of a Compact Imaging X-ray Spectrometer) instrument on the ESA SMART-1 mission is to provide high quality spectroscopic mapping of the Moon by imaging fluorescence X-rays emitted from the lunar surface. In order to obtain adequate statistics for what can be very weak sources, it is essential to have a large effective area, while maintaining a low mass. The solution is to make a thin, low profile detector, essentially a modern version of “X-ray detecting paper”. D-CIXS will achieve a spatial resolution on the ground of 42km from a spacecraft at 300 km altitude, with a spectral resolution of 200 eV or better. The instrument is based around the use of advanced dual microstructure collimator and Swept Charge Device X-ray detector technologies. Swept Charge Device X-ray detectors, a novel architecture based on proven CCD technology, have the virtue of providing superior X-ray detection and spectroscopic measurement capabilities, while also operating at room temperature. Thus we avoid the need for the large passive cooling radiator that was previously required to cool large X-ray focal plane CCDs. The advanced low profile microstructure collimation and filter design builds on expertise developed in solid state and microwave technology to enable us to dramatically reduce the instrument mass. The total mass of D-CIXS, including an X-ray solar monitor is ∼4.6 kg. D-CIXS will provide the first global map of the Moon in X-rays. During normal solar conditions, it will be able to detect absolute elemental abundances of Fe, Mg, Al and Si on the lunar surface, using the on-board solar monitor to obtain a continuous measurement of the input solar spectrum. During solar flare events, it will also be possible to detect other elements such as Ca, Ti, V, Cr, Mn, Co, K, P and Na. The global mapping of Mg, Al and Si, and in particular deriving Mg#, the magnesium number (MgO/[MgO+FeO]), represents the prime goal of the D-CIXS experiment.

The Chandrayaan-1 X-ray Spectrometer (C1XS) flown on-board the first Indian lunar mission Chandrayaan-1, measured X-ray fluorescence spectra during several episodes of solar flares during its operational period of � 9 months. The accompanying X-ray Solar Monitor (XSM) provided simultaneous spectra of solar X-rays incident on the Moon which are essential to derive elemental chemistry. In this paper, we present the surface abundances of Mg, Al, Si, Ca and Fe, derived from C1XS data for a highland region on the southern nearside of the Moon. Analysis techniques are described in detail including absolute X-ray line flux derivation and conversion into elemental abundance. The results are consistent with a composition rich in plagioclase with a slight mafic mineral enhancement and a Ca/Al ratio that is significantly lower than measured in lunar returned samples. We suggest various possible scenarios to explain the deviations.

The Chandrayaan-1 X-ray Spectrometer (C1XS) was launched onboard the Indian Space Research Organisation (ISRO) Chandrayaan-1 lunar mission in October 2008. The instrument consisted of 24 swept-charge device silicon X-ray detectors providing a total collecting area of ~24 cm2, corresponding to a 14° field of view (FWHM), with the ability to measure X-rays from 0.8 - 10 keV. During the 10 months the spacecraft was located in orbit around the Moon a number of solar flare X-ray events were detected, along with calibration data from X-ray sources housed inside the movable door of the instrument. This paper presents a study of the degradation in spectral resolution of the measured X-ray calibration lines, comparing those recorded mid way through the mission lifetime with ground based calibration data collected prior to the launch of the instrument. The radiation environment the detectors were subjected to is discussed in light of the actual radiation damage effects on the spectral resolution observed in flight.

This is the post-print version of the final paper published in Planetary and Space Science. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2009 Elsevier B.V. The Chandrayaan-1 X-ray Spectrometer (C1XS) is a compact X-ray spectrometer for the Indian Space Research Organisation (ISRO) Chandrayaan-1 lunar mission. It exploits heritage from the D-CIXS instrument on ESA's SMART-1 mission. As a result of detailed developments to all aspects of the design, its performance as measured in the laboratory greatly surpasses that of D-CIXS. In comparison with SMART-1, Chandrayaan-1 is a science-oriented rather than a technology mission, leading to far more favourable conditions for science measurements. C1XS is designed to measure absolute and relative abundances of major rock-forming elements (principally Mg, Al, Si, Ca and Fe) in the lunar crust with spatial resolution ⩽25 FWHM km, and to achieve relative elemental abundances of better than 10%. ESA Science and Technology Research Programmes

The demonstration of a compact imaging X-ray spectrometer (D-CIXS), which flew on ESA's SMART-1 mission to the Moon (Racca et al., 2001; Foing et al., 2006), was designed to test innovative new technologies for orbital X-ray fluorescence spectroscopy. D-CIXS conducted observations of the lunar surface from January 2005 until SMART-1 impacted the Moon in September 2006. Here, we present scientific observations made during two solar flare events and show the first detection of Titanium Kα from the lunar surface. We discuss the geological implications of these results. We also discuss how experience from D-CIXS has aided the design of a similar instrument (Chandrayaan-1 X-ray Spectrometer (C1XS)) that was launched on the 22nd October 2008 on India's Chandrayaan-1 mission to the Moon.

The UK-built Chandrayaan-1 X-ray Spectrometer (C1XS) will fly as an ESA instrument on India's Chandrayaan-1 mission to the Moon, launched in October 2008. C1XS builds on experience gained with the earlier D-CIXS instrument on SMART-1, but will be a scientifically much more capable instrument. Here we describe the scientific objectives of this instrument, which include mapping the abundances of the major rock-forming elements (principally Mg, Al, Si, Ti, Ca and Fe) in the lunar crust. These data will aid in determining whether regional compositional differences (e.g., the Mg/Fe ratio) are consistent with models of lunar crustal evolution. C1XS data will also permit geochemical studies of smaller scale features, such as the ejecta blankets and central peaks of large impact craters, and individual lava flows and pyroclastic deposits. These objectives all bear on important, and currently unresolved, questions in lunar science, including the structure and evolution of any primordial magma ocean, as revealed by vertical and lateral geochemical variations in the crust, and the composition of the lunar mantle, which will further constrain theories of the Moon's origin, thermal history and internal structure.

The Chandrayaan-1 X-ray Spectrometer (C1XS) will be launched as part of the Indian Space Research Organisation (ISRO) Chandrayaan-1 payload in September 2008, arriving at the Moon within 7 days to begin a two year mission in lunar orbit conducting mineralogical surface mapping over the range of 1 – 10 keV. The detector plane of the instrument consists of twenty four e2v technologies CCD54 swept-charge devices (SCDs). Such devices were first flown in the Demonstration of a Compact Imaging X-ray Spectrometer (D-CIXS) instrument onboard SMART-1 [4, 5]. The detector plane in each case provides a total X-ray collection area of 26.4 cm 2 . The SCD is capable of providing near Fano-limited spectroscopy at -10 o C, and at -20 o C, near the Chandrayaan-1 mission average temperature, it achieves a total system noise of 6.2 electrons r.m.s. and a FWHM of 134 eV at Mn-Kα. This paper presents a brief overview of the C1XS mission and a detailed study of the effects of proton irradiation on SCD operational performance.

Ribulosc bisphosphate carboxylase/oxygenase was purified to apparent homogeneity from the carboxysomes of Prochlorothrix hollandica.The MW of the native enzyme was estimated to be 560,000 Dalton, comprising large subunits (LSU) of 57,000 Dalton and small subunits (SSU) of 13,000, probably in an 8LSU8SSU quaternary structure. Enzyme activity was maximal at pH 8.0 at 30°C. The requirement of activity for Mg2+ could not be replaced by Mn2+, Co2+, Ca2+ or Cu2+.Amino acid N-terminal sequence analysis of the LSU showed a high degree of conservation when compared to cyanobacterial and chloroplast LSU sequences but was too short to allow a reliable phylogenetic assignment of P. hollandica.

The Indian Space Research Organisation (ISRO) Chandrayaan-1 mission is India's first lunar spacecraft, containing a suite of instruments to carry out high-resolution remote sensing of the Moon at visible, near infrared and X-ray wavelengths. Due for launch in early 2008, the spacecraft will carry out its two year mission in a polar orbit around the Moon at an altitude of 100 km. One of the eleven instruments in the spacecraft payload is the Chandrayaan-1 X-ray Spectrometer (C1XS), a descendant of the successful D-CIXS instrument that flew on the European Space Agency SMART-1 lunar mission launched in 2003. C1XS consists of 24 swept-charge device (SCD) silicon X-ray detectors arranged in 6 modules that will carry out high quality X-ray spectroscopic mapping of the Moon using the technique of X-ray fluorescence. This paper presents an overview of the Chandrayaan-1 mission and specifically the C1XS instrument and describes the development of an SCD test facility, proton irradiation characterisation and screening of candidate SCD devices for the mission.

The SMART-1 mission has recently arrived at the Moon. Its payload includes D-CIXS, a compact X-ray spectrometer. SMART-1 is a technology evaluation mission, and D-CIXS is the first of a new generation of planetary X-ray spectrometers. Novel technologies enable new capabilities for measuring the fluorescent yield of a planetary surface or atmosphere which is illuminated by solar X-rays. During the extended SMART-1 cruise phase, observations of the Earth showed strong argon emission, providing a good source for calibration and demonstrating the potential of the technique. At the Moon, our initial observations over Mare Crisium show a first unambiguous remote sensing of calcium in the lunar regolith. Data obtained are broadly consistent with current understanding of mare and highland composition. Ground truth is provided by the returned Luna 20 and 24 sample sets. (c) 2006 Elsevier Ltd. All rights reserved.

The role of electrostatic interactions in determining the rate of electron transfer between cytochrome f and plastocyanin has been examined in vitro with mutants of turnip cytochrome f and mutants of pea and spinach plastocyanins. Mutation of lysine residues Lys58, Lys65 and Lys187 of cytochrome f to neutral or acidic residues resulted in decreased binding constants and decreased rates of electron transfer to wild-type pea plastocyanin. Interaction of the cytochrome f mutant K187E with the pea plastocyanin mutant D51K gave a further decrease in electron transfer rate, indicating that a complementary charge pair at these positions could not compensate for the decreased overall charge on the proteins. Similar results were obtained with the interaction of the cytochrome f mutant K187E with single, double and triple mutants of residues in the acidic patches of spinach plastocyanin. These results suggest that the lysine residues of the basic patch on cytochrome f are predominantly involved in long-range electrostatic interactions with plastocyanin. However, analysis of the data using thermodynamic cycles provided evidence for the interaction of Lys187 of cytochrome f with Asp51, Asp42 and Glu43 of plastocyanin in the complex, in agreement with a structural model of a cytochrome f-plastocyanin complex determined by NMR.

The ratio of urinary testosterone (T) to epitestosterone (EpiT) is used to detect T abuse in sport. Also, plasma or urinary concentrations of EpiT have been measured to assess testicular steroidogenesis during hormonal male contraception. Further investigations are required to evaluate the relative contributions of the testis and adrenal to EpiT production. To this purpose, we have compared basal urinary EpiT glucuronide and plasma EpiT and the response to synthetic adrenocorticotrophic hormone (ACTH) stimulation between eugonadal and hypogonadal men.The basal urinary excretion rate of EpiT glucuronide was determined in 34 eugonadal men. Six men, clinically diagnosed as hypogonadal, and 6 out of the 34 eugonadal men previously described, received an intramuscular injection of synthetic ACTH depot (1 mg) at 0800 h on two consecutive days. Blood samples were collected prior to and then at 1.5, 8, 24, 25.5, 32 and 48 h with respect to the first administration (0 h). 24-h urine specimens were collected from 0800 h on days 1 and 2 (baseline) and 3 and 4 (stimulation).Plasma EpiT, T and cortisol were measured by RIA and urinary EpiT and T, following glucuronide hydrolysis, by gas chromatography-mass spectrometry (extract combines aglycones with a minor amount of urinary free steroids).Basal excretion rates of EpiT glucuronide in eugonadal men (range: 62-751 nmol/24 h) were considerably greater than in hypogonadal men (range: 3-34 nmol/24 h). Mean basal plasma EpiT in eugonadal men (1.32 +/- 0.08 nmol/l) were greater than in hypogonadal men (0.68 +/- 0.04 nmol/l). In each group, synthetic ACTH stimulation increased plasma cortisol 4-fold. In eugonadal men, plasma and urinary EpiT were unchanged whereas plasma and urinary T glucuronide decreased in response to ACTH. In hypogonadal patients, ACTH increased plasma and urinary EpiT while plasma T remained unchanged.The testes are the major source of epitestosterone, the adrenal contribution being relatively modest. Following adrenal stimulation, urinary epitestosterone glucuronide increases considerably in hypogonadal men but this increase is masked in eugonadal men because testicular production is probably suppressed by the ACTH-induced rise in cortisol. Activation of the adrenal cortex results in no change or only a small decrease in the urinary T/EpiT ratio in eugonadal men.

One certainty for nursing, and therefore for nursing education, is that nurses of the 21st century will be called upon to deliver aggregate-based care. Faculty, seeking ways to prepare students for this challenge, often use community assessment as a strategy to help develop skills required to implement care at the aggregate level. In this unique program, community projects completed during an undergraduate community and family health nursing course are expanded in scope to include community diagnosis, planning, intervention, and outcome evaluation. Projects offer immediate benefit to the agency and may continue for several semesters, involving students in various phases of the nursing process.

We have identified and sequenced a cDNA containing a complete open reading frame for a putative 340-amino acid precursor of the thylakoidal processing peptidase from Arabidopsis thaliana. The predicted amino acid sequence of the protein includes regions highly conserved among Type I leader peptidases and indicates that the enzyme uses a serine-lysine catalytic dyad mechanism. Phylogenetic analysis indicated a common ancestry of the enzyme with those from oxygenic photosynthetic prokaryotes, suggesting that the cDNA encoded the chloroplast enzyme. The catalytic domain was overexpressed in Escherichia coli, generating a product capable of cleaving the thylakoid-transfer domain from a chloroplast protein. Antibodies to the overexpressed polypeptide cross-reacted with a 30-kDa thylakoid membrane protein.

Field studies of androgen pharmacology are complicated by the necessity to collect, process, and store blood samples in a central facility. We have assessed the feasibility of using capillary blood spots collected by fingerprick and dried on filter paper for pharmacokinetics and pharmacodynamic measurements with nandrolone and testosterone RIAs modified for extracts from capillary blood spots. Assays on punched spots of 7.9-mm diameter (14.9 microL of dried blood) permitted accurate quantification of testosterone down to 0.4 nmol/L from a single spot and nandrolone down to 0.9 nmol/L from two spots. Stability of the steroids in dried blood spots to adverse environmental conditions, notably increased temperatures, was investigated both in the laboratory and in field studies of dried spots sent through the postal system. Storage or postal transport under moderate conditions appeared to have no deleterious effects on apparent androgen concentrations. However, under extreme conditions of storage at 50 degrees C for a week or more, or transport to a very hot tropical location, a rise in the final concentration of nandrolone, and, to a lesser extent, testosterone when corrected for tracer recovery, was noticed. These effects were largely due to apparent susceptibility of tritiated tracer, but not unlabeled androgen, to thermal degradation. In a pilot pharmacological study involving intramuscular injection of 100 mg of nandrolone decanoate in 1 mL of arachis oil, nandrolone concentrations in concurrently collected plasma as well as venous and capillary blood spots showed good agreement. Testosterone concentrations in contemporaneously collected plasma and venous blood spots also showed very good agreement. We propose that these methods may allow patients and experimental subjects to self-collect samples at remote or field locations for convenient mailing to a central laboratory for androgen assay. Applications of this methodology are now under way.

Cyanobacteria possess thylakoid membranes that differ in their protein composition from the cytoplasmic membrane. To study possible pathways of protein targeting to these membranes, we have investigated whether or not cyanobacteria have a homologue or homologues of the signal recognition particle-like chaperone Ffh. We have amplified a fragment of ffh by polymerase chain reaction and established that ffh is present as a single copy in the genomes of three cyanobacterial species. We have cloned and sequences ffh from Synechococcus sp. PCC7942 and predict that Ffh functions as a ribonucleoprotein in cyanobacteria and chloroplasts.

In September 1993, the Institute of Medicine released a report entitled Adverse Events Associated With Childhood Vaccines: Evidence Bearing on Causality. The report examined putative serious adverse consequences associated with administration of diphtheria and tetanus toxoids; measles, mumps, and measles-mumps-rubella vaccines; oral polio vaccine and inactivated polio vaccine; hepatitis B vaccines; and Haemophilus influenzae type b (Hib) vaccines. The committee spent 18 months reviewing all available scientific and medical data, from individual case reports (published and unpublished) to controlled clinical trials. The committee found that the evidence favored the rejection of a causal relation between diphtheria and tetanus toxoids and encephalopathy, infantile spasms, and sudden infant death syndrome, and between conjugate Hib vaccines and susceptibility to Hib disease. The committee found that the evidence favored acceptance of a causal relation between diphtheria and tetanus toxoids and Guillain-Barré syndrome and brachial neuritis, between measles vaccine and anaphylaxis, between oral polio vaccine and Guillain-Barré syndrome, and between unconjugated Hib vaccine and susceptibility to Hib disease. The committee found that the evidence established causality between diphtheria and tetanus toxoids and anaphylaxis, between measles vaccine and death from measles vaccine-strain viral infection, between measles-mumps-rubella vaccine and thrombocytopenia and anaphylaxis, between oral polio vaccine and poliomyelitis and death from polio vaccine-strain viral infection, and between hepatitis B vaccine and anaphylaxis. For five vaccine-related adverse events, there was no evidence identified. For the remaining 33 vaccine-related adverse events, the evidence was inadequate to accept or reject a causal relation.

This article is a report of our experience with an interdisciplinary pain service in a large tertiary care pediatric hospital. During the first 2 years of operation, we received 869 consultations and referrals from more than 19 hospital divisions. Postoperative pain was the most frequent reason for consultation (56% of patients). Patients with pain related to cancer and sickle cell disease comprised 25% of the consultations. The remaining patients had a wide variety of primary diagnoses and causes of pain. We calculated the time spent by pain service physicians in direct patient care. The majority (63%) of physician time was spent with a small number of patients (17%). Most of these patients had pain that was unrelated to surgery, cancer, or sickle cell disease, and many posed dilemmas in diagnosis and treatment. Physician time was correlated directly to the use of psychologic and physical therapies for the pain, involving multiple team members. This experience supports the demand for an interdisciplinary pain service in a tertiary care children's hospital. A significant amount of physician time is necessary to provide patient care and to maintain a team approach, however, and pediatricians and other health care professionals who aim to implement such services should be cognizant of the time required.

The assessment and management of a child's pain in the postoperative period remain a challenge to the PACU nurse. Assessment of pain in children is often difficult; ongoing clinical research in this area continues to expand knowledge of how to improve children's communication of their pain to caregivers. Many pain management strategies are available, both pharmacologic and nonpharmacologic, to ease pain and distress postoperatively. Through understanding and knowledge of pain, its assessment and its management, the PACU nurse contributes positively to the child's surgical experience.

Following exposure to UV light the synthesis of six polypeptides (112, 100, 89, 76, 71 and 65 kDa) was found to be enhanced or induced in the alga Chlamydomonas reinhardtii. Treatment with 4-nitroquinoline-N-oxide (NQO) resulted in the enhanced/induced synthesis of six polypeptides with molecular masses similar to those enhanced following exposure to UV light. Heat shock resulted in the enhanced synthesis of five polypeptides (89, 76, 71, 60 and 22 kDa), three of which (89, 76 and 71 kDa) had apparently identical mobilities to polypeptides whose synthesis was enhanced following UV treatment.

Detection of heterozygote carriers for congenital adrenal hyperplasia by use of a modified tetracosactide (a synthetic corticotropin) stimulation test with prior overnight dexamethasone suppression proved to have a diagnostic accuracy of 95%. Discrimination of heterozygotes from normals was best when we used a criterion based on the ratios of 17 alpha-hydroxyprogesterone to cortisol at baseline and at 30 min after intravenous administration of 250 micrograms of tetracosactide.

The major purpose of this investigation was to determine the effect of prednisolone and megestrol acetate in cats on the adrenal cortisol response to exogenous adrenocorticotrophic hormone during drug administration at dose rates employed for management of some inflammatory feline dermatoses. Prednisolone (at least 2 mg/kg/day) and megestrol acetate (5 mg/cat/day) were each administered orally to seven cats from days 1 to 16. Three additional cats received no therapy. Basal and stimulated cortisol concentrations, food and water intake, hematology, blood biochemistry, urinalyses, and hepatic and cutaneous histology were studied in all cats before, during, and two weeks following the end of treatment. Cats given prednisolone or megestrol acetate had significant suppression of stimulated cortisol levels on day 8. This change was more marked on day 15, when the suppression in cats given megestrol acetate was also significantly more severe than in those receiving prednisolone. Recovery of adrenal reserve was considered present on day 30 in six of seven cats given prednisolone, but in only three of seven receiving megestrol acetate. Eosinopenia, glycosuria and hepatocyte swelling from glycogen deposition were occasionally recorded in treated cats of both groups, providing additional circumstantial evidence for glucocorticoid activity of megestrol acetate in cats. It is advised that abrupt withdrawal of prednisolone or megestrol acetate therapy be avoided in this species to reduce the chance of precipitating clinical signs of hypoadrenocorticism, even after treatment for as little as one week.