Rational design of peptide-based HIV proteinase inhibitors

A series of peptide derivatives based on the transition-state mimetic concept has been designed that inhibit the proteinase from the human immunodeficiency virus (HIV). The more active compounds inhibit both HIV-1 and HIV-2 proteinases in the nanomolar range with little effect at 10 micromolar against the structurally related human aspartic proteinases. Proteolytic cleavage of the HIV-1 gag polyprotein (p55) to the viral structural protein p24 was inhibited in chronically infected CEM cells. Antiviral activity was observed in the nanomolar range (with one compound active below 10 nanomolar) in three different cell systems, as assessed by p24 antigen and syncytium formation. Cytotoxicity was not detected at 10 and 5 micromolar in C8166 and JM cells, respectively, indicating a high therapeutic index for this new class of HIV proteinase inhibitors.

The prevalence of childhood atopic eczema in a general population

BACKGROUND

Atopic eczema has become more common during recent decades, but few studies have looked at its prevalence in the general community.

OBJECTIVE

Our purpose was to ascertain the prevalence of atopic eczema, its age of onset, and its relationship to breast-feeding and ear piercing in a general practice population.

METHODS

Children (N = 1104), aged 3 to 11 years, were identified from a computerized register in a socially and ethnically mixed English general practice population of 13,314. Of these, 1077 children (97.6% recruitment) were interviewed with parents or guardians, and the resultant data were recorded on a survey form.

RESULTS

The lifetime occurrence of atopic eczema was 20% in boys (12% in the past year) and 19% in girls (11% in the past year). Prevalence in the past year was 10% to 14% in boys aged 3 to 11 years but fell in girls from 15% at 3 to 5 years to 8% at 9 to 11 years. Atopic eczema developed in the first 12 months of life in 60% of the children who had the condition, and it developed in the first 6 months of life in three quarters of these children. Ear piercing had been performed in 35% of girls and 3% of boys and was most prevalent in social classes 3, 4, and 5. More than half the girls aged 9 to 11 years had pierced ears. Breast-feeding did not affect the prevalence of atopic eczema.

CONCLUSION

The lifetime prevalence of atopic eczema was 20% in children aged 3 to 11 years. There was no evidence that ear piercing perpetuated eczema in this age group. Breast-feeding did not protect against the development of atopic eczema.

Letter-by-letter reading: psychological descriptions of a neurological syndrome

Following a general description of the characteristics of letter-by-letter reading and a summary of previous explanations of this reading deficit in both neurological and psychological models, four single-case studies of patients with this syndrome are presented. One central topic, addressed by experimental investigation, concerns comprehension of written words. Despite the use of multiple techniques, no evidence was obtained for the hypothesis that comprehension of a word could occur prior to or in the absence of the letter-by-letter analysis required for oral reading. It appears that these patients must do sequential letter identification of a word in order both to understand it and to report it. A second central topic, addressed through analysis of reading errors, concerns procedures for word recognition. Two of the four patients showed a “pure” letter-by-letter syndrome, with no difficulty in word recognition once the component letters had been identified. For the other two patients, an additional lexical deficit often prevented a correctly identified sequence of letters from achieving recognition as the correct word. Alternative interpretations of these patterns are discussed in terms of a process model.

Activation of CD4 cells by fibronectin and anti-CD3 antibody. A synergistic effect mediated by the VLA-5 fibronectin receptor complex

In this study, fibronectin synergized with anti-CD3 antibody to promote CD4 cell proliferation in a serum-free culture system. The cell-adhesive domain plus additional regions of the fibronectin molecule are involved in this synergy. Anti4B4(CDw29) antibody blocked the activation of CD4 cells in this system. Furthermore, it is the VLA-5 protein within the set of molecules recognized by anti-4B4 that serves as a fibronectin receptor on the CD4 lymphocytes. The VLA-5 fibronectin receptor was mainly expressed on CD4+ CD45R-CDw29+ cells and may in part contribute to the unique function of these cells.

Aspartic proteases of Plasmodium falciparum and other parasitic protozoa as drug targets

All parasitic protozoa contain multiple proteases, some of which are attracting attention as drug targets. Aspartic proteases are already the targets of some clinically useful drugs (e.g. chemotherapy of HIV infection) and a variety of factors make these enzymes appealing to those seeking novel antiparasite therapies. This review provides a critical analysis of the current knowledge on Plasmodium aspartic proteases termed plasmepsins, proposes a definitive nomenclature for this group of enzymes, and compares these enzymes with aspartic proteases of humans and other parasitic protozoa. The present status of attempts to obtain specific inhibitors of the parasite enzymes that will be useful as drugs is outlined and suggestions for future research priorities are proposed.

Epidemiology of headache and childhood migraine in an urban general practice using Ad Hoc, Vahlquist and IHS criteria

In a survey conducted by a UK urban general practice, 98.1 per cent (1083) of the children registered aged three to 11 years took part in an interview. Possible migraine subjects took part in an extended interview, the results of which were recorded using three different sets of diagnostic criteria: Vahlquist, Ad Hoc and International Headache Society. The prevalence of migraine ranged from 3.7 to 4.9 per cent, depending on the criteria used. The prevalence of migraine with aura (1.5 per cent) was similar by all criteria, whereas that for migraine without aura ranged from 2.2 to 3.4 per cent. The prevalence of migraine increased with age. The IHS criteria appeared less sensitive than the Ad Hoc for migraine without aura. Operational criteria using three attacks lasting longer than one hour may be more specific for the diagnosis of migraine in young children.

Antigen processing for presentation by class II major histocompatibility complex requires cleavage by cathepsin E

Proteolytic degradation (processing) of antigen by antigen-presenting cells is a major regulatory step in the activation of a T lymphocyte immune response. However, the enzymes responsible for antigen processing remain largely undefined. In this study we show that cathepsin E, and not the ubiquitous lysosomal cathepsin D, is the major aspartic proteinase in a murine antigen-presenting cell line, A20. This enzyme is localized to a non-lysosomal compartment of the endosomal system in these cells. Functional studies using a highly specific inhibitor of cathepsin E show that this enzyme is essential for the processing of ovalbumin by this cell line. Thus, cathepsin E, whose function was hitherto unknown, may play a major role in antigen processing.

The role of interleukin-1 in the pathogenesis of rheumatoid arthritis

A significant body of experimental evidence has implicated the proinflammatory cytokine IL-1 in the pathogenesis of RA. For example, IL-1beta overexpression in rabbit knee joints causes arthritis with clinical and histological features characteristic of RA, whereas IL-1 deficiency is associated with reduced joint damage. In experimental models, IL-1 blockers, including IL-1 receptor antagonist (IL-1Ra), significantly reduce clinical and histological disease parameters. In RA patients, plasma and synovial fluid concentrations of IL-1 are elevated, and these correlate with various parameters of disease activity. The production of endogenous IL-1Ra, however, appears to be insufficient to balance these higher IL-1 levels. The efficacy of blocking IL-1 in patients with active RA has been established in controlled clinical trials of anakinra, a recombinant human IL-1Ra (r-metHuIL-1ra). When used alone or in combination with methotrexate, anakinra significantly reduces the clinical signs and symptoms of RA compared with placebo. Taken together, these results indicate that IL-1 plays an important role in the pathogenesis of RA.

A prospective survey of reactions to blood tests by children and adolescents

A sample of 171 children and adolescents aged 3-17 years requiring venepuncture for blood sampling were asked to report on their pain and anxiety and were observed immediately before and during blood drawing. Depending on the measures used, 36-64% of children from 3 to 6 years old experienced moderate to severe distress from blood drawing. Multiple regression analysis revealed that age and the parents' prediction of how upset the child would feel before the blood test was a significant predictor of the observed distress and the self-report of pain. Experience with previous needle procedures did not add significantly to the prediction of distress. Identification of children at high risk to respond poorly to painful medical procedures is discussed.

Effective blocking of HIV-1 proteinase activity by characteristic inhibitors of aspartic proteinases

Inhibitory constants (Ki) between 5 and 35 nM were derived (under different conditions of pH and ionic strength) for the interaction of HIV-1 proteinase with acetyl-pepstatin and H-261, two characteristic inhibitors of aspartic proteinases. Thus this enzyme, essential for replication of the AIDS virus, may be classified unequivocally as belonging to this proteinase family.

A systematic series of synthetic chromophoric substrates for aspartic proteinases

The hydrolysis of the chromogenic peptide Pro-Thr-Glu-Phe-Phe(4-NO2)-Arg-Leu at the Phe-Phe(4-NO2) bond by nine aspartic proteinases of animal origin and seven enzymes from micro-organisms is described [Phe(4-NO2) is p-nitro-L-phenylalanine]. A further series of six peptides was synthesized in which the residue in the P3 position was systematically varied from hydrophobic to hydrophilic. The Phe-Phe(4-NO2) bond was established as the only peptide bond cleaved, and kinetic constants were obtained for the hydrolysis of these peptide substrates by a representative selection of aspartic proteinases of animal and microbial origin. The value of these water-soluble substrates for structure-function investigations is discussed.

Isolation and characterization of beta-glucan receptors on human mononuclear phagocytes

beta-glucan receptors, with ligand specificity for yeast and fungal carbohydrate polymers, have been studied as phagocytic receptors of human monocytes. To characterize their structure, binding studies were carried out with human U937 cells and a rabbit IgG anti-Id that recognizes epitopes on monocyte beta-glucan receptors. Unstimulated U937 cells specifically bound large amounts of the anti-Id, but almost none of the control anti-isotype. At saturation, the number of anti-Id molecules bound per U937 cell was 2.6 x 10(6) with an apparent Ka of 1.9 x 10(7) M-1. Immunoprecipitates from detergent lysates of surface-radioiodinated U937 cells contained only two membrane proteins with antigenic specificity for the anti-Id, one having a mol wt of 180 kD and the other 160 kD. Both proteins were disulfide-linked and presented, after reduction, as five polypeptides of 95, 88, 60, 27, and 20 kD. Detergent lysates of unlabeled U937 cells, purified by affinity chromatography on anti-Id-Sepharose, yielded the same two nonreduced proteins and five reduction products in slab gels stained with Coomassie blue. In Western blots probed with the anti-Id, the most immunoreactive nonreduced and reduced affinity-purified products were the 160 and 20 kD molecules, respectively. Immunoblots of two-dimensional gels showed the 180 and 160 kD proteins to express a common epitope through disulfide linkage to the 20 kD polypeptide. By immunoblot analysis, U937 cell glucan-binding proteins from detergent lysates contained two cell proteins antigenic for the anti-Id that were indistinguishable from affinity-purified molecules in size and subunit composition. Studies of affinity-purified proteins from detergent lysed human monocytes were characterized by immunoblot analysis and found to be identical to U937 cell beta-glucan receptors. They consisted of two disulfide-linked proteins, with mol wt of 180 and 160 kD, and had in common a 20 kD polypeptide with the anti-Id epitope.

A cognitive neuropsychological case study of anomia. Implications for psychological models of word retrieval

The case of a neurological patient with severe anomic word-finding difficulties is reported. A detailed cognitive neuropsychological investigation of the patient's ability to name objects to confrontation was carried out in an attempt to determine where his cognitive deficits might lie. In contrast to the findings of recent case studies of word-finding difficulty (e.g., Howard and Orchard-Lisle, 1984), it was observed that the patient seemed to have a clear understanding of the items that he was trying to name, suggesting that his problems in word-finding were not semantically based. Indeed, the patient would often generate partial phonological information about the sought-after word, indicating that he had a specific target in mind, and this was reminiscent of 'tip-of-the-tongue' states in normal word-finding. A difficulty in retrieving complete phonological forms of words is considered as the probable locus of his anomia. A distinction is made between semantically-based and phonologically-based anomias.

High level expression and characterisation of Plasmepsin II, an aspartic proteinase from Plasmodium falciparum

DNA encoding the last 48 residues of the propart and the whole mature sequence of Plasmepsin II was inserted into the T7 dependent vector pET 3a for expression in E. coli. The resultant product was insoluble but accumulated at approximately 20 mg/l of cell culture. Following solubilisation with urea, the zymogen was refolded and, after purification by ion-exchange chromatography, was autoactivated to generate mature Plasmepsin II. The ability of this enzyme to hydrolyse several chromogenic peptide substrates was examined; despite an overall identity of approximately 35% to human renin, Plasmepsin II was not inhibited significantly by renin inhibitors.

Effect of age on long-term heart rate variability

OBJECTIVE

Previous studies on short-term time series of heart rage suggest an inverse relationship between age and spectral powers of heart rate variability in various frequency bands. In this study, we examined the relationship between age (6-61 years) and long-term heart rate variability.

METHODS

We obtained 24-h Holter ECG in 33 healthy human subjects (11 children and 22 adults). The heart rate data were analyzed by using spectral analysis and fractal dimensions of the time series.

RESULTS

We found a significant negative correlation between age and very low frequency (VLF, 0.0033-0.04 Hz), low frequency (LF, 0.04-0.15 Hz) and high frequency (HF, 0.15-0.5 Hz) powers and fractal dimensions during awake as well as sleep periods, and a positive correlation between age and LF/HF ratios. Age and ultra-low frequency (ULF, < 0.0033 Hz) were modestly and negatively correlated only during the awake period.

CONCLUSIONS

Sleep ULF power is not significantly affected by age, whereas VLF, LF and HF powers and fractal dimensions of heart rate significantly decrease with age during awake as well as sleep periods.

Fine structure of the murine leptin receptor gene: splice site suppression is required to form two alternatively spliced transcripts

The fine structure of the murine leptin receptor gene (Lepr) is described. Duplicated ligand binding domains (conserved among cytokine receptors) are found in eight exons (coding exons 3 to 6 and 8 to 11). Thus, it is possible that a single leptin receptor molecule could have two functional ligand binding domains. The transmembrane region of Lepr is in coding exon 16 while the juxtamembrane JAK docking site is in coding exon 17. For all membrane-bound forms, the transcript must include 17 invariant exons and 1 alternatively spliced 3' terminal exon. The transcript encoding the soluble receptor (Re) includes 14 coding exons and an alternatively spliced 3' terminal exon. We have identified two splice variants (Rc and Re) for which there are no intervening sequences between the two final exons. This unusual juxtaposition of exons requires that splice donor sites at the 5' end of the respective terminal exons be ignored in the production of these splice variants. We suggest that splice site suppression is responsible for the formation of two of the alternatively spliced forms of the mouse Lepr gene. The juxtaposition of two coding exons separated by a consensus splice donor sequence is the structural substrate for this mode of alternative splicing. We present evidence that the Rc form is expressed in human tissues while the Re form, the soluble receptor, is not expressed.

Temporal lobe epilepsy, temporal lobectomy, and major depression

Sixty-two patients with medically intractable complex partial seizures who had either surgical or no surgical intervention were followed up at a mean of 10.9 years after surgery or initial evaluation. Of the 49 surgical patients, 45% had a life-time history of depression, versus 15% of the 13 patients in the nonsurgical comparison group. In the surgical group, 77% had prior history of depression; of these, 47% experienced no further episodes after surgery. Depression occurred de novo after lobectomy in 5 surgical patients (approximately 10%), 4 developing depression within 1 year. Presurgical presence of depressive episodes predicted continued postoperative depressive episodes. The significantly higher depression rate in patients with temporal lobe seizure foci suggests limbic system dysfunction in the increased risk for depression. Postsurgical resolution of episodes in almost 50% of these patients supports the tenet that depression per se is not a contraindication for surgery in patients with intractable seizures.

Immunolocalization of cathepsin D in normal and neoplastic human tissues

The aspartic proteinase cathepsin D was purified from human spleen and localised in various formalin fixed paraffin embedded human tissues using the peroxidase-antiperoxidase (PAP) technique. Cathepsin D was shown not only in macrophages but also in other connective tissue cells, and in epithelium. It was present in spleen (littoral cells and cells within Malpighian bodies), liver (hepatocytes and Kupffer cells), lung (alveolar macrophages and bronchial epithelium), brain (neurones), lymph nodes (histiocytes in germinal centres, sinusoid lining cells) and stomach (parietal and mucous neck cells). Cathepsin D was also found in carcinomas of bronchus, stomach, colon, kidney, breast, ovary, bladder and pancreas, both in neoplastic epithelium and in stromal cells, but was seldom present in connective tissue neoplasms. A group of malignant lymphomas also contained the enzyme within scattered cells. The distribution of cathepsin D seems to be much wider than that of the structurally related aspartic proteinases pepsin, gastricsin, and renin.

Sequence, expression and modeled structure of an aspartic proteinase from the human malaria parasite Plasmodium falciparum

A clone encoding the aspartic proteinase (PFAPD) from Plasmodium falciparum strain HB3 was obtained during the course of a project designed to sequence and identify the protein coding regions of the parasite's genome. The protein encoded by the clone contains a sequence identical to the N-terminal sequence determined for an aspartic proteinase isolated from the digestive vacuole of P. falciparum and demonstrated to participate in the hemoglobin digestive pathway (D. Goldberg, personal communication). The translated polypeptide sequence encompasses a number of features characteristic of aspartic proteinases, having > 30% identity and > 50% similarity overall to human cathepsin D, cathepsin E and renin. A model of the three-dimensional structure of PFAPD was constructed using rule-based procedures. This confirms that the primary sequence may be folded as a single chain into a three dimensional structure closely resembling those of other known aspartic proteinases. It includes a lengthy prosegment, two typical-hydrophobic-hydrophobic-Asp-Thr/Ser-Gly motifs and a tyrosine residue positioned in a beta-hairpin loop. The distribution of hydrophobic residues throughout the active site cleft is indicative of a likely preference for hydrophobic polypeptide substrates. The recombinant form of this enzyme expressed using the pGEX2T vector in Escherichia coli is active in digesting hemoglobin at acidic pH and in hydrolyzing a synthetic peptide corresponding to the putative initial cleavage site in hemoglobin. Activity is inhibited completely by pepstatin, confirming the identity of PFAPD as a member of the aspartic proteinase family. Specific mRNA for PFAPD is expressed in the erythrocytic stages of the life cycle.

Different requirements for productive interaction between the active site of HIV-1 proteinase and substrates containing -hydrophobic*hydrophobic- or -aromatic*pro- cleavage sites

The sequence requirements for HIV-1 proteinase catalyzed cleavage of oligopeptides containing two distinct types of junctions (-hydrophobic*hydrophobic- or -aromatic*Pro-) has been investigated. For the first type of junction (-hydrophobic*hydrophobic-) the optimal residues in the P2 and P2' positions were found to be Val and Glu, respectively, in accord with recent statistical analysis of natural cleavage sites [Poorman, R. A., Tomasselli, A. G., Heinrikson, R. L., & Kézdy, F. J. (1991) J. Biol. Chem. 266, 14554-14561]. For the -aromatic*Pro- type of junction, in the specific sequence context studied here, the value of Glu in the P2' position was again observed. An explanation for the inefficient cleavage observed for peptides with the sequence -Val-Tyr*Pro- has been provided from molecular modeling of the putative enzyme-substrate complex. A significant effect upon cleavage rates due to the amino acid in the P5 position has also been documented. While lysine in the P5 position in one sequence of the -hydrophobic*hydrophobic- type produces a peptide cleaved very efficiently (kcat greater than 15 s-1 for Lys-Ala-Arg-Val-Nle*p-nitrophenylalanine-P2'-Ala-Nle-NH2, for P2' = Glu, Gln, Ile, Val, or Ala), for substrates of the -aromatic*Pro- type, the P5 residue can exert either a positive or negative effect on cleavage rates. These results have again been interpreted in light of molecular modeling. We suggest that interaction of the substrate sequence on the periphery of the active site cleft may influence the match of the enzyme-substrate pair and, hence, control the efficiency of catalysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression and characterisation of plasmepsin I from Plasmodium falciparum

Two aspartic proteinases, plasmepsins I and II, are present in the digestive vacuole of the human malarial parasite Plasmodium falciparum and are believed to be essential for parasite degradation of haemoglobin. Here we report the expression and kinetic characterisation of functional recombinant plasmepsin I. In order to generate active plasmepsin I from its precursor, an autocatalytic cleavage site was introduced into the propart of the zymogen by mutation of Lys110P to Val (P indicates a propart residue). Appropriate refolding of the mutated zymogen then permitted pH-dependent autocatalytic processing of the zymogen to the active mature proteinase. A purification scheme was devised that removed aggregated and misfolded protein to yield pure, fully processable, proplasmepsin I. Kinetic constants for two synthetic peptide substrates and four inhibitors were determined for both recombinant plasmepsin I and recombinant plasmepsin II. Plasmepsin I had 5-10-fold lower k(cat)/Km values than plasmepsin II for the peptide substrates, while the aspartic proteinase inhibitors, selected for their ability to inhibit P. falciparum growth, were found to have up to 80-fold lower inhibition constants for plasmepsin I compared to plasmepsin II. The most active plasmepsin I inhibitors were antagonistic to the antimalarial action of chloroquine on cultured parasites. Northern blot analysis of RNA, isolated from specific stages of the erythrocytic cycle of P. falciparum, showed that the proplasmepsin I gene is expressed in the ring stages whereas the proplasmepsin II gene is not transcribed until the later trophozoite stage of parasite growth. The differences in kinetic properties and temporal expression of the two plasmepsins suggest they are not functionally redundant but play distinct roles in the parasite.

Adding gabapentin to a multimodal regimen does not reduce acute pain, opioid consumption or chronic pain after total hip arthroplasty

BACKGROUND

Gabapentin (GPN) is effective in reducing post-operative pain and opioid consumption, but its effects with regional anesthesia for total hip arthroplasty (THA) are not known. We designed this study to determine whether (1) gabapentin administration reduces pain and opioid use after THA using a multimodal analgesic regimen including spinal anesthesia; (2) pre-operative administration of gabapentin is more effective than post-operative administration.

METHODS

After REB approval and informed consent, 126 patients were enrolled in a double-blinded, randomized-controlled study. Patients received acetaminophen 1 g per os (p.o.), celecoxib 400 mg p.o. and dexamethasone 8 mg intravenously, 1-2 h pre-operatively. Patients were randomly assigned to one of three treatment groups (G1: Placebo/Placebo; G2: GPN/Placebo; G3: Placebo/GPN). Patients received gabapentin 600 mg (G2) or placebo (G1 and G3) 2 h before surgery. All patients had spinal anesthesia [15 mg (3cc) of 0.5% hypobaric bupivacaine with 10 microg of fentanyl]. In the post-anesthetic care unit, patients received gabapentin 600 mg (G3) or placebo (G1 and G2). On the ward, patients received acetaminophen 1000 mg p.o. q6h, celecoxib 200 mg p.o. q12h and a morphine PCA device. Patients were interviewed 6 months post-surgery to determine the incidence and severity of chronic post-surgical pain.

RESULTS

Mean+/-SD cumulative morphine (mg) consumption (G1=49.4+/-24.8, G2=47.2+/-30.1 and G3=56.1+/-38.2) at 48 h and pain scores at 12, 24, 36 and 48 h post-surgery were not significantly different among the groups [G1 (n=38), G2 (n=38) and G3 (n=38)]. Side effect profiles were similar across groups. Six months after surgery, the number of patients who reported chronic post-surgical pain (G1=10, G2=12 and G3=9) and the severity of the pain (G1=4.2+/-2.9, G2=4.1+/-2.2 and G3=4.9+/-2.2) did not differ significantly among the groups (P>0.05).

CONCLUSIONS

A single 600 mg dose of gabapentin given pre-operatively or post-operatively does not reduce morphine consumption or pain scores in hospital or at 6 months after hip arthroplasty within the context of spinal anesthesia and a robust multimodal analgesia regimen.

Epidural triamcinolone suppresses the pituitary-adrenal axis in human subjects

Epidural steroids (ESI) are often used for the treatment of low back pain but their effects on the endocrine system have not been determined. We studied the hypothalamic-pituitary adrenal (HPA) axis in 14 patients by measuring plasma adrenocorticotropin (ACTH) by sensitive two-site immunoradiometric assay and by evaluating the acute cortisol response to cosyntropin. We also evaluated the additional impact of sedation with midazolam before ESI on the degree of suppression of the HPA axis. Plasma ACTH and cortisol were significantly suppressed 7 days after the first ESI; the group receiving midazolam was more suppressed. By 14 days after the first ESI (7 days after the second ESI), plasma ACTH was more suppressed in the group receiving midazolam and plasma cortisol was markedly suppressed in both groups. At 48 days after the first ESI (34 days after the third ESI), plasma ACTH and cortisol were significantly suppressed only in the group that had received midazolam before each ESI. At 48 days, the plasma cortisol response to cosyntropin was blunted (< 500 nmol/L) in 5 of 14 patients. All patients had a normal cortisol response to cosyntropin by 3 mo after the last ESI. Weekly ESI over 3 wk caused a dramatic acute and chronic suppression of the HPA axis. Median suppression was less than 1 mo, and all patients had recovered by 3 mo. Sedation with midazolam accentuated the suppression of the HPA axis. Exogenous steroid coverage during this potentially vulnerable period should be considered in patients undergoing major stress especially if the adrenocortical response to ACTH is subnormal.