Early maternal and child influences on children's later independent cognitive and social functioning

The present study examined whether parenting and child characteristics of 2- and 3 1/2-year-old children had common paths of influence on their 4 1/2-year independent cognitive and social functioning. Structural equation modeling was guided by hypotheses that assumed children's later independence is facilitated by specialized parental support in early social interactions. To address the importance of variability in early development for understanding children's later independence, we included 104 term and 185 preterm children, as they are known to differ in early skills. As predicted, mothers' maintaining of children's interests indirectly supported 4 1/2-year cognitive and social independence through a direct, positive influence on 2- and 3 1/2-year skills. Directiveness positively supported children's early cognitive and responsiveness skills but by 3 1/2 years, high levels of this behavior had a direct, negative influence on their cognitive and social independence at 4 1/2 years. Whereas high levels of maintaining interests across these ages support later independence, directiveness needs to decrease in relation to children's increasing competencies. Results support a theoretical framework that emphasizes the importance of the social context for understanding the origins of children's later independent functioning.

In vitro insecticidal effects of fipronil and beta-cyfluthrin on larvae of the blowfly Lucilia sericata

The insecticidal effects of the phenylpyrazole, fipronil, and a pyrethroid, beta-cyfluthrin, on larvae of the blowfly Lucilia sericata were determined in laboratory assays. When first stage larvae of L. sericata were reared on homogenized pig liver which had been treated with known amounts of test compounds, both fipronil and beta-cyfluthrin induced significant levels of mortality compared to acetone and water controls. However, fipronil was approximately 10 times more toxic than beta-cyfluthrin to L. sericata larvae following ingestion. Beta-cyfluthrin had little effect on mortality until concentrations of approximately 0.5 ppm were reached. In contrast, fipronil effected L. sericata mortality at a concentration of 0.05 ppm and 100% mortality was reached by 0.5 ppm. The lethal concentration (LC50) value for beta-cyfluthrin was 1.56 ppm as compared to 0.14 ppm for fipronil. Following contact of first and third stage larvae with cloth impregnated with known amounts of test compound, the mortality profiles of fipronil and beta-cyfluthrin were similar. At short contact times, the LC50 values for fipronil were lower than those for beta-cyfluthrin. However, at the highest contact time evaluated for the first stage larvae, 300 s, there was a reversal in this trend. The results suggest that the phenylpyrazole fipronil may represent a new potential insecticide for development against blowfly strike of sheep.

Galanin receptor subtypes

The neuropeptide galanin, which is widely expressed in brain and peripheral tissues, exerts a broad range of physiological effects. Pharmacological studies using peptide analogues have led to speculation about multiple galanin receptor subtypes. Since 1994, a total of three G-protein-coupled receptor (GPCR) subtypes for galanin have been cloned (GAL1, gal2 and gal3). Potent, selective antagonists are yet to be found for any of the cloned receptors. Major challenges in this field include linking the receptor clones with each of the known physiological actions of galanin and evaluating the evidence for additional galanin receptor subtypes.

Particles and vegetation: implications for the transfer of particle-bound organic contaminants to vegetation

This paper presents a comprehensive review of the mechanisms responsible for the transfer of atmospheric particulate deposition and soil particulate re-suspension onto vegetation. The nature of atmospheric aerosols and dry/wet particulate deposition are reviewed, together with information from the literature on radionuclides as tracers of the air particle/soil particle to vegetation transfer processes. Information from these fields is used to make inferences about the potential significance of these pathways in supplying particle-bound semi-volatile organic chemicals (e.g. polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls) to vegetation. Retention of compounds on particles brought to the above-ground plant surfaces is discussed. In the absence of definitive field/experimental studies, calculations are made drawing on the literature data to estimate the contributions of atmospheric and soil particle-bound organic contaminants to the plant concentration. These show that depending on the site-specific, species-specific and compound-specific scenarios considered, particulate-bound inputs may be negligible or may dominate the supply of organic contaminants to the above-ground portion of plants. However, field/experimental studies and direct measurements are needed to provide reliable quantitative data on this topic.

Relation of mothers' affective developmental history and parenting behavior: effects on infant medical risk

Mothers of infants with varying degrees of medical risk were grouped according to their perception of acceptance or rejection in childhood. Those who recalled the highest degree of acceptance showed greater warmth and flexibility as parents, regardless of their infants' degree of medical risk. However, infant medical risk was an important moderator in relations between maternal perceptions of childhood rejection and parental behavior.

Assessment of the diabetic foot using spiral computed tomography imaging and plantar pressure measurements: a technical report

Persons with diabetes mellitus (DM) and peripheral neuropathy are at high risk for skin breakdown due to unnoticed excessive pressures to the plantar foot during walking. We developed methods that combined spiral x-ray computed tomography (SXCT) imaging and plantar pressure analysis to quantify internal foot structure and external pressure during plantar loading. Methods were tested using a subject with DM who had a plantar ulcer, and a healthy control. SXCT measurements were within 2 mm of truth and SXCT plantar recordings were within 6.5% of walking trials. Hammer toe deformity (second toe), severe atrophy of the intrinsic muscles and less contact area during plantar loading, and a peak plantar pressure three times greater at the site of the ulcer were measured in the diabetic foot as compared with the healthy control. This preliminary investigation suggests that these methods are accurate for structural and pressure measurements of diabetic and healthy feet.

Microbial transformations of steroids-XI. Progesterone transformation by Streptomyces roseochromogenes-purification and characterisation of the 16alpha-hydroxylase system

Streptomyces roseochromogenes, NCIB 10984, contains a cytochrome P450 which, in conjunction with two indigenous electron transfer proteins, roseoredoxin and roseoredoxin reductase, hydroxylates exogenous progesterone firstly to 16alpha-hydroxyprogesterone and thereafter in a second phase bioconversion to 2beta,16alpha-dihydroxyprogesterone. The progesterone 16alpha-hydroxylase P450 and the two electron transfer proteins have been purified to homogeneity. A reconstituted incubation containing these three purified proteins and NADH, the natural electron donor, produced identical hydroxy-progesterone metabolites as in intact cells. Peroxy and hydroperoxy compounds act in a shortened form of the cycle known as the 'peroxide shunt' by replacing the natural pathway requirement for the electron donor NADH, the electron transfer proteins and molecular O2, the terminal electron acceptor. In an NaIO4 supported incubation, the initial rate of progesterone hydroxylation was marginally higher (1.62 mmol progesterone/mmol P-450/h) than in the reconstituted natural incubation (1.18 mmol progesterone/mmol P-450/h) but the product yield was significantly lower, 0.45 mol hydroxyprogesterone produced/mol P-450 compared to 6.0 mol hydroxyprogesterone produced/mol P-450. These yield data show that in the reconstituted natural pathway, progesterone 16alpha-hydroxylase P450 supports multiple rounds of hydroxylation in contrast to a likely single oxygenation by a minority of P450s in the peroxide shunt pathway.

Computer-assisted 3D reconstruction of serial sections of cortical bone to determine the 3D structure of osteons

The objective of this study was to create three-dimensional (3D) images for the histomorphological study of osteons. Medical imaging technology was used to register digitized 2D images of serial decalcified histological sections of bone, to segment the tissues of interest from the surrounding tissues, and to create 3D reconstructions from the segmented structures. Examination of the 3D reconstructions did not support suggestions in the literature that osteons have a spiraling organization. In contrast, the 3D reconstructions indicated that osteons have a complex pattern of organization that is dominated by branching. Examination of the reconstructions also suggested that osteons described in the literature as being dumbbell shaped are actually artifacts of the plane of sectioning. This study demonstrated the applicability of imaging and visualization technology developed for the 3D reconstruction of medical images to the reconstruction of digitized 2D images of serial sections of bone and additionally demonstrated the feasibility of using 3D reconstructions for the histomorphological study of osteons.

Feeding, medical factors, and developmental outcome in premature infants

This is a prospective, longitudinal study of premature infants investigating whether the length of time needed to reach full enteral feedings (FEF) or full nipple feedings (FNF) is related to medical complications and/or developmental outcome at 24 months corrected age. Premature infants (n = 161) from three institutions with birth weights less than 1,600 grams were followed up from birth to 24 months corrected age. The infants were stratified into groups by the severity of medical complications. Bayley Scales of Infant Development were performed at 24 months corrected age. Multiple linear regression was used to analyze the association between feeding milestones, medical complications, and developmental outcomes. Our results show that when controlling for birth weight and gestational age (GA), the severity of respiratory complications was significantly related to reaching FEF (p = 0.024) and FNF (p = 0.0014). Furthermore, when controlling for the severity of respiratory complications, GA, and socioeconomic status, an increased length of time to FEF was significantly associated with a poorer mental outcome (p = 0.0013). We conclude that there is an association between the length of time to reach FEF and mental developmental outcome at 24 months corrected age. Infants who reach full enteral feedings at an earlier age appear to have a better developmental outcome despite their GA and severity of respiratory complications.

Food-borne disease in the 21st century. What challenges await us?

As the world shrinks and international commerce expands, food-borne illness is likely to become a major public health focus worldwide. Improved surveillance, community education, thorough understanding of the food production chain, use of HACCP strategies, and ionizing radiation are all important for reducing the risks. Primary care physicians play a crucial role in surveillance and early reporting, as well as in educating the public on the importance of basic food safety.

Within-flock transmission of sheep scab in naive sheep housed with single infested sheep

The within flock transmission of sheep scab was studied in two trials, which lasted 14 and 12 weeks, respectively. A total of 40 non-infested, scab-naive sheep were divided into six groups of between 6 and 20 individuals. Each group was subsequently housed with a single infested index case, carrying scab lesions of different ages. The groups of sheep in both trials were video recorded continuously and all the sheep were individually examined on a weekly basis. The occurrence of transmission was measured in two ways: first, by the detection of early scab lesions during clinical examination and, second, by an increase in the rubbing of individual sheep as noted from the analysis of the video recordings. These two methods complemented each other in predicting the week on which transmission occurred. Overall, transmission was detected in 34 of the 40 scab-naive sheep. Transmission was shown to occur at about the time when the population of adult mites in lesions on index cases reached their peak numbers. The highest number of mites at this time, however, differed markedly between index sheep. There was no obvious relationship between the incidence of transmission and the time index sheep spent rubbing each day or other index sheep variables, including the age of the lesion or the time since the introduction to the scab free sheep.

Simulation analysis of the population dynamics of the mite, Psoroptes ovis, infesting sheep

The pattern of population growth of the ectoparasitic mite, Psoroptes ovis (Acari: Psoroptidae), on its ovine host is considered through the development of a Leslie matrix-based, simulation model. The model is parameterised using experimental data in conjunction with reanalysis of published data. The model shows that on sheep P. ovis populations grow at a rate of approximately 11% per day and the population doubles every 6.3 days. Additional rates of adult mortality, in excess of 50% per day, need to be imposed to prevent population growth. The predictions of the model are tested by comparison of the expected numbers of mites with the numbers recorded in lesions either on naturally infested sheep where the date of infestation can be estimated or on one artificially infested animal, where the initial number of mites and date of infestation are known precisely. In both cases the observed number of mites in lesions relate closely to the numbers expected from the simulations. The model simulations do not support the concept of a 'lag' phase as distinct from the 'growth' phase in the changing pattern of mite abundance on an infested sheep and suggests that the observed pattern of growth is a natural function of an exponential increase in numbers. The development of such models and their use in explaining the demographic processes which drive mite population dynamics are discussed.

The effects of temperature and humidity on the off-host survival of Psoroptes ovis and Psoroptes cuniculi

The effects of both temperature and humidity on the survival of the mites Psoroptes ovis and Psoroptes cuniculi were considered in laboratory assays. When P. ovis and P. cuniculi were maintained at 95% humidity, maximum survival decreased linearly with increasing temperature, from approximately 15 days at 9 degrees C to 5 days at 30 degrees C. There was no significant difference between P. ovis and P. cuniculi in the effects of temperature on maximum survival. Adult male P. ovis and P. cuniculi had lower mean maximum survival than any of the other life cycle stages. There was a small but significant effect of humidity on survival for P. cuniculi; LT50 values were greater at 75-85% r.h. than at 55-65% r.h. The influence of off-host survival and the infestation of naive sheep from mites in the environment on the epidemiology of sheep scab are discussed.

Quinolone-resistant Campylobacter jejuni infections in Minnesota, 1992-1998. Investigation Team

BACKGROUND

Increasing resistance to quinolones among campylobacter isolates from humans has been reported in Europe and Asia, but not in the United States. We evaluated resistance to quinolones among campylobacter isolates from Minnesota residents during the period from 1992 through 1998.

METHODS

All 4953 campylobacter isolates from humans received by the Minnesota Department of Health were tested for resistance to nalidixic acid. Resistant isolates and selected sensitive isolates were tested for resistance to ciprofloxacin. We conducted a case-comparison study of patients with ciprofloxacin-resistant Campylobacter jejuni isolated during 1996 and 1997. Domestic chicken was evaluated as a potential source of quinolone-resistant campylobacter.

RESULTS

The proportion of quinolone-resistant C. jejuni isolates from humans increased from 1.3 percent in 1992 to 10.2 percent in 1998 (P<0.001). During 1996 and 1997, infection with quinolone-resistant C. jejuni was associated with foreign travel and with the use of a quinolone before the collection of stool specimens. However, quinolone use could account for no more than 15 percent of the cases from 1996 through 1998. The number of quinolone-resistant infections that were acquired domestically also increased during the period from 1996 through 1998. Ciprofloxacin-resistant C. jejuni was isolated from 14 percent of 91 domestic chicken products obtained from retail markets in 1997. Molecular subtyping showed an association between resistant C. jejuni strains from chicken products and domestically acquired infections in Minnesota residents.

CONCLUSIONS

The increase in quinolone-resistant C. jejuni infections in Minnesota is largely due to infections acquired during foreign travel. However, the number of quinolone-resistant infections acquired domestically has also increased, largely because of the acquisition of resistant strains from poultry. The use of fluoroquinolones in poultry, which began in the United States in 1995, has created a reservoir of resistant C. jejuni.

Use of computed tomography and plantar pressure measurement for management of neuropathic ulcers in patients with diabetes

BACKGROUND AND PURPOSE

Total contact casting is effective at healing neuropathic ulcers, but patients have a high rate (30%-57%) of ulcer recurrence when they resume walking without the cast. The purposes of this case report are to describe how data from plantar pressure measurement and spiral x-ray computed tomography (SXCT) were used to help manage a patient with recurrent plantar ulcers and to discuss potential future benefits of this technology.

CASE DESCRIPTION

The patient was a 62-year-old man with type 1 diabetes mellitus (DM) of 34 years' duration, peripheral neuropathy, and a recurrent plantar ulcer. Although total contact casting or relieving weight bearing with crutches apparently allowed the ulcer to heal, the ulcer recurred 3 times in an 18-month period. Spiral x-ray computed tomography and simultaneous pressure measurement were conducted to better understand the mechanism of his ulceration.

OUTCOMES

The patient had a severe bony deformity that coincided with the location of highest plantar pressures (886 kPa). The results of the SXCT and pressure measurement convinced the patient to wear his prescribed footwear always, even when getting up in the middle of the night. The ulcer healed in 6 weeks, and the patient resumed his work, which required standing and walking for 8 to 10 hours a day.

DISCUSSION

Following intervention, the patient's recurrent ulcer healed and remained healed for several months. Future benefits of these methods may include the ability to define how structural changes of the foot relate to increased plantar pressures and to help design and fabricate optimal orthoses.

Induction of steroidal hydroxylase activity by plant defence compounds in the filamentous fungus Cochliobolus lunatus

We investigated the hypothesis that the endogenous role of the commercially important inducible steroid hydroxylase cytochrome P450s of fungi was in defense against plant toxophores/secondary metabolites. Two plant defense compounds, the aglycones tomatidine and solanidine, the steroidal glycoalkaloid alpha-tomatine and the triterpene saponin beta-escin were tested as inducers of 11beta/14alpha-steroid hydroxylase in the filamentous fungus Cochliobolus lunatus. The extracts of saponins from the roots of Primula veris and green oat leaves were also tested as inducers of 11beta/14alpha-hydroxylation activity in progesterone biotransformation with the same fungus. Induction of steroid hydroxylase and inhibition of activity in some cases support our hypothesis that their endogenous function is in biochemical defence against secondary metabolites. 4-Pregnene-3,11,20-trione was added as a substrate for biotransformation with C. lunatus. We isolated from culture broth 14alpha-hydroxy-4-pregnene-3,11,20-trione, and the hitherto unreported compounds, 7alpha,14alpha-dihydroxy-4-pregnene-3,11,20-trione and 7alpha-hydroxy-pregna-4,8(14)-diene-3,11,20-trione.

Molecular biology and pharmacology of galanin receptors

Galanin was first isolated 15 years ago. Diversity of galanin receptors has been suspected from the study of native tissues and functional responses to galanin and galanin-like peptides in vitro and in vivo. The recent application of molecular biologic techniques to clone galanin receptors has extended this diversity. So far, three galanin receptor subtypes, GALR1, GALR2, and GALR3, have been cloned from both human and rat. Their molecular structure, pharmacologic profiles, tissue distribution, and signal transduction properties have been partially elucidated.

GABA(B) receptors function as a heteromeric assembly of the subunits GABA(B)R1 and GABA(B)R2

The principal inhibitory neurotransmitter GABA (gamma-aminobutyric acid) exerts its effects through two ligand-gated channels, GABA(A) and GABA(C) receptors, and a third receptor, GABA(B) , which acts through G proteins to regulate potassium and calcium channels. Cells heterologously expressing the cloned DNA encoding the GABA(B)R1 protein exhibit high-affinity antagonist-binding sites, but they produce little of the functional activity expected from studies of endogenous GABA(B) receptors in the brain. Here we describe a new member of the GABA(B) polypeptide family, GABA(B)R2, that shows sequence homology to GABA(B)R1. Neither GABA(B)R1 nor GABA(B)R2, when expressed individually, activates GIRK-type potassium channels; however, the combination of GABA(B)R1 and GABA(B)R2 confers robust stimulation of channel activity. Both genes are co-expressed in individual neurons, and both proteins co-localize in transfected cells. Moreover, immunoprecipitation experiments indicate that the two polypeptides associate with each other, probably as heterodimers. Several G-protein-coupled receptors (GPCRs) exist as high-molecular-weight species, consistent with the formation of dimers by these receptors, but the relevance of these species for the functioning of GPCRs has not been established. We have now shown that co-expression of two GPCR structures, GABA(B)R1 and GABA(B)R2, belonging to the same subfamily is essential for signal transduction by GABA(B) receptors.

Partitioning of rhodanese onto GroEL. Chaperonin binds a reversibly oxidized form derived from the native protein

The mammalian mitochondrial enzyme, rhodanese, can form stable complexes with the Escherichia coli chaperonin GroEL if it is either refolded from 8 M urea in the presence of chaperonin or is simply added to the chaperonin as the folded conformer at 37 degreesC. In the presence of GroEL, the kinetic profile of the inactivation of native rhodanese followed a single exponential decay. Initially, the inactivation rates showed a dependence on the chaperonin concentration but reached a constant maximum value as the GroEL concentration increased. Over the same time period, in the absence of GroEL, native rhodanese showed only a small decline in activity. The addition of a non-denaturing concentration of urea accelerated the inactivation and partitioning of rhodanese onto GroEL. These results suggest that the GroEL chaperonin may facilitate protein unfolding indirectly by interacting with intermediates that exist in equilibrium with native rhodanese. The activity of GroEL-bound rhodanese can be completely recovered upon addition of GroES and ATP. The reactivation kinetics and commitment rates for GroEL-rhodanese complexes prepared from either unfolded or native rhodanese were identical. However, when rhodanese was allowed to inactivate spontaneously in the absence of GroEL, no recovery of activity was observed upon addition of GroEL, GroES, and ATP. Interestingly, the partitioning of rhodanese and its subsequent inactivation did not occur when native rhodanese and GroEL were incubated under anaerobic conditions. Thus, our results strongly suggest that the inactive intermediate that partitions onto GroEL is the reversibly oxidized form of rhodanese.

Suppression of the blowfly Lucilia sericata using odour-baited triflumuron-impregnated targets

Field trials were carried out in 1995 and 1996 on farms in the south-west of England to assess the extent to which odour-baited targets could be used to suppress populations of the ectoparasitic blowfly, Lucilia sericata, in sheep pastures. Targets were constructed from 41 x 41 cm squares of aluminium sheet, covered by white cloth which had been dipped in a mixture of sucrose solution (50% w/v) and the chitin synthesis inhibitor triflumuron (10% suspension concentrate). Each target was baited with approximately 300 g of liver and sodium sulphide solution (10%). Three matched sheep farms were used in the trials. In 1995, triflumuron-impregnated targets were placed around the periphery of sheep pastures at one of the farms in late June, at approximately one target per hectare. In 1996, triflumuron-impregnated targets were placed around the periphery of sheep pastures of a second of the farms in early May, at approximately five targets per hectare. Each year, five sticky targets, used to monitor the L. sericata populations, were also placed in fields at the experimental and the other two farms, which acted as controls. In 1995, the results provided some, although inconclusive, evidence that the triflumuron-impregnated targets had reduced the numbers of L. sericata relative to the populations on the two control farms. In 1996, however, the density of L. sericata on the experimental farm was reduced to almost zero and remained significantly lower than on two control farms throughout the period during which the triflumuron-impregnated targets remained in the field. The results are discussed in relation to the use of triflumuron-treated targets as a practical means of controlling L. sericata and sheep blowfly strike.

Progesterone 6-hydroxylation is catalysed by cytochrome P-450 in the moderate thermophile Bacillus thermoglucosidasius strain 12060

The moderate thermophile, Bacillus thermoglucosidasius, transforms progesterone into four metabolites. These are 6alpha- and 6beta-hydroxyprogesterone, androstenedione and testosterone. This is the first report of bacterial 6alpha-hydroxylation of steroids. The identity of the progesterone metabolites shows that there are three major types of transforming activity in this organism; C-17-C-20 lyase that cleaves the pregnane side chain of the substrate, C-17 oxidoreductase that interconverts the metabolites androstenedione and testosterone, and 6-hydroxylation. 6-hydroxylation activity was purified virtually to homogeneity and was shown to be catalysed by a cytochrome P-450 monooxygenase enzyme. This is the first report of a thermostable cytochrome P-450.

Cloned human and rat galanin GALR3 receptors. Pharmacology and activation of G-protein inwardly rectifying K+ channels

The neuropeptide galanin has been implicated in the regulation of processes such as nociception, cognition, feeding behavior, and hormone secretion. Multiple galanin receptors are predicted to mediate its effects, but only two functionally coupled receptors have been reported. We now report the cloning of a third galanin receptor distinct from GALR1 and GALR2. The receptor, termed GALR3, was isolated from a rat hypothalamus cDNA library by both expression and homology cloning approaches. The rat GALR3 receptor cDNA can encode a protein of 370 amino acids with 35% and 52% identity to GALR1 and GALR2, respectively. Localization of mRNA by solution hybridization/RNase protection demonstrates that the GALR3 transcript is widely distributed, but expressed at low abundance, with the highest levels in the hypothalamus and pituitary. We also isolated the gene encoding the human homologue of GALR3. The human GALR3 receptor is 90% identical to rat GALR3 and contains 368 amino acids. Binding of porcine 125I-galanin to stably expressed rat and human GALR3 receptors is saturable (rat KD = 0.98 nM and human KD = 2.23 nM) and displaceable by galanin peptides and analogues in the following rank order: rat galanin, porcine galanin approximately M32, M35 approximately porcine galanin-(-7 to +29), galantide, human galanin > M40, galanin-(1-16) > [D-Trp2]galanin-(1-29), galanin-(3-29). This profile resembles that of the rat GALR1 and GALR2 receptors with the notable exception that human galanin, galanin-(1-16), and M40 show lower affinity at GALR3. In Xenopus oocytes, activation of rat and human GALR3 receptors co-expressed with potassium channel subunits GIRK1 and GIRK4 resulted in inward K+ currents characteristic of Gi/Go-coupled receptors. These data confirm the functional efficacy of GALR3 receptors and further suggest that GALR3 signaling pathways resemble those of GALR1 in that both can activate potassium channels linked to the regulation of neurotransmitter release.

Effects of metyrapone on hepatic cortisone-cortisol conversion in the rat

In previous studies in human subjects metyrapone has been found to exert significant extra-adrenal effects, consistent with an effect on the 11-reductase activity of 11beta-hydroxysteroid dehydrogenase (11beta-HSD). In the present study the effects of metyrapone on cortisone metabolism by rat liver microsomes were investigated. Aliquots of microsomal preparations were incubated with NADPH cofactor and different concentrations of cortisone for a range of time intervals up to 30 min. The products of the reaction were extracted with ethyl acetate and separated using thin-layer chromatograph. Cortisol was estimated by radioimmunoassay. There was a linear increase in cortisol formation over the first 150 sec of the reaction. Over this time period metyrapone had no effect on the rate of the reaction. When the reaction was allowed to proceed for 30 min, however, metyrapone caused a 50% decrease in the amount of cortisol formed. These data suggest that metyrapone may alter cortisone-cortisol conversion by directly interacting with 11beta-HSD but in this system metyrapone does not appear to have the characteristics of a conventional enzyme inhibitor.