Intensive Care Delirium Screening Checklist: evaluation of a new screening tool

OBJECTIVE

Delirium in the intensive care unit is poorly defined. Clinical evaluation is difficult in the setting of unstable, often intubated patients. A screening tool may improve the detection of delirium.

METHOD

We created a screening checklist of eight items based on DSM criteria and features of delirium: altered level of consciousness, inattention, disorientation, hallucination or delusion, psychomotor agitation or retardation, inappropriate mood or speech, sleep/wake cycle disturbance, and symptom fluctuation. During 3 months, all patients admitted to a busy medical/surgical intensive care unit were evaluated, and the scale score was compared to a psychiatric evaluation.

RESULTS

In 93 patients studied, 15 developed delirium. Fourteen (93%) of them had a score of 4 points or more. This score was also present in 15 (19%) of patients without delirium, 14 of whom had a known psychiatric illness, dementia, a structural neurological abnormality or encephalopathy. A ROC analysis was used to determine the sensitivity and specificity of the screening tool. The area under the ROC curve is 0.9017. Predicted sensitivity is 99% and specificity is 64%.

CONCLUSION

This study suggests that the Intensive Care Delirium Screening Checklist can easily be applied by a clinician or a nurse in a busy critical care setting to screen all patients even when communication is compromised. The tool can be utilized quickly and helps to identify delirious patients. Earlier diagnosis may lead to earlier intervention and better patient care.

The complete BRCA2 gene and mutations in chromosome 13q-linked kindreds

Breast carcinoma is the most common malignancy among women in developed countries. Because family history remains the strongest single predictor of breast cancer risk, attention has focused on the role of highly penetrant, dominantly inherited genes in cancer-prone kindreds (1). BRCA1 was localized to chromosome 17 through analysis of a set of high-risk kindreds (2), and then identified four years later by a positional cloning strategy (3). BRCA2 was mapped to chromosomal 13q at about the same time (4). Just fifteen months later, Wooster et al. (5) reported a partial BRCA2 sequence and six mutations predicted to cause truncation of the BRCA2 protein. While these findings provide strong evidence that the identified gene corresponds to BRCA2, only two thirds of the coding sequence and 8 out of 27 exons were isolated and screened; consequently, several questions remained unanswered regarding the nature of BRCA2 and the frequency of mutations in 13q-linked families. We have now determined the complete coding sequence and exonic structure of BRCA2 (GenBank accession #U43746), and examined its pattern of expression. Here, we provide sequences for a set of PCR primers sufficient to screen the entire coding sequence of BRCA2 using genomic DNA. We also report a mutational analysis of BRCA2 in families selected on the basis of linkage analysis and/or the presence of one or more cases of male breast cancer. Together with the specific mutations described previously, our data provide preliminary insight into the BRCA2 mutation profile.

A candidate prostate cancer susceptibility gene at chromosome 17p

It is difficult to identify genes that predispose to prostate cancer due to late age at diagnosis, presence of phenocopies within high-risk pedigrees and genetic complexity. A genome-wide scan of large, high-risk pedigrees from Utah has provided evidence for linkage to a locus on chromosome 17p. We carried out positional cloning and mutation screening within the refined interval, identifying a gene, ELAC2, harboring mutations (including a frameshift and a nonconservative missense change) that segregate with prostate cancer in two pedigrees. In addition, two common missense variants in the gene are associated with the occurrence of prostate cancer. ELAC2 is a member of an uncharacterized gene family predicted to encode a metal-dependent hydrolase domain that is conserved among eukaryotes, archaebacteria and eubacteria. The gene product bears amino acid sequence similarity to two better understood protein families, namely the PSO2 (SNM1) DNA interstrand crosslink repair proteins and the 73-kD subunit of mRNA 3' end cleavage and polyadenylation specificity factor (CPSF73).

Delirium in an intensive care unit: a study of risk factors

OBJECTIVES

(1) To establish risk factors for the development of delirium in an intensive care unit (ICU) and (2) to determine the effect of delirium on morbidity, mortality and length of stay.

DESIGN

Prospective study.

SETTING

Sixteen-bed medical/surgical ICU in a university hospital.

PATIENTS

Two hundred and sixteen consecutive patients admitted to the ICU for more than 24 h during 5 months were included in the study.

INTERVENTIONS

Medical history, selected laboratory values, drugs received and factors that may influence patient psychological and emotional well-being were noted. All patients were screened with a delirium scale. A psychiatrist confirmed the diagnosis of delirium. Major complications such as self-extubation and removal of catheters, as well as mortality and length of stay were recorded.

RESULTS

Forty patients (19%) developed delirium; of these, one-third were not agitated. In the multivariate analysis hypertension, smoking history, abnormal bilirubin level, epidural use and morphine were statistically significantly associated with delirium. Traditional factors associated with the development of delirium on general ward patients were not significant in our study. Morbidity (self-extubation and removal of catheters), but not mortality, was clearly increased.

CONCLUSION

Predictive risk factors for the development of delirium in studies outside the ICU may not be applicable to critically ill patients. Delirium is associated with increased morbidity. Awareness of patients at risk may lead to better recognition and earlier intervention.

Biochemical and genetic analysis of the yeast proteome with a movable ORF collection

Functional analysis of the proteome is an essential part of genomic research. To facilitate different proteomic approaches, a MORF (moveable ORF) library of 5854 yeast expression plasmids was constructed, each expressing a sequence-verified ORF as a C-terminal ORF fusion protein, under regulated control. Analysis of 5573 MORFs demonstrates that nearly all verified ORFs are expressed, suggests the authenticity of 48 ORFs characterized as dubious, and implicates specific processes including cytoskeletal organization and transcriptional control in growth inhibition caused by overexpression. Global analysis of glycosylated proteins identifies 109 new confirmed N-linked and 345 candidate glycoproteins, nearly doubling the known yeast glycome.

Risk factors for suicide completion in major depression: a case-control study of impulsive and aggressive behaviors in men

OBJECTIVE

Major depression is a major risk factor for suicide. However, not all individuals with major depression commit suicide. Impulsive and aggressive behaviors have been proposed as risk factors for suicide, but it remains unclear whether their effect on the risk of suicide is at least partly explained by axis I disorders commonly associated with suicide, such as major depression. With a case-control design, a comparison of the level of impulsive and aggressive behaviors and the prevalence of associated psychopathology was carried out with control for the presence of primary psychopathology.

METHOD

One hundred and four male suicide completers who died during an episode of major depression and 74 living depressed male comparison subjects were investigated with proxy-based interviews by using structured diagnostic instruments and personality trait assessments.

RESULTS

The authors found that current (6-month prevalence) alcohol abuse/dependence, current drug abuse/dependence, and cluster B personality disorders increased the risk of suicide in individuals with major depression. Also, higher levels of impulsivity and aggression were associated with suicide. An analysis by age showed that these risk factors were more specific to younger suicide victims (ages 18-40). A multivariate analysis indicated that current alcohol abuse/dependence and cluster B personality disorder were two independent predictors of suicide.

CONCLUSIONS

Impulsive-aggressive personality disorders and alcohol abuse/dependence were two independent predictors of suicide in major depression, and impulsive and aggressive behaviors seem to underlie these risk factors. A developmental hypothesis of suicidal behavior, with impulsive and aggressive behaviors as the starting point, is discussed.

The wide spectrum of multidrug resistance 3 deficiency: from neonatal cholestasis to cirrhosis of adulthood

BACKGROUND & AIMS

We have specified the features of progressive familial intrahepatic cholestasis type 3 and investigated in 31 patients whether a defect of the multidrug resistance 3 gene (MDR3) underlies this phenotype.

METHODS

MDR3 sequencing, liver MDR3 immunohistochemistry, and biliary phospholipid dosage were performed.

RESULTS

Liver histology showed a pattern of biliary cirrhosis with patency of the biliary tree. Age at presentation ranged from the neonatal period to early adulthood. Sequence analysis revealed 16 different mutations in 17 patients. Mutations were identified on both alleles in 12 patients and only on 1 allele in 5. Four mutations lead to a frame shift, 2 are nonsense, and 10 are missense. An additional missense mutation probably representing a polymorphism was found in 5 patients. MDR3 mutations were associated with abnormal MDR3 canalicular staining and a low proportion of biliary phospholipids. Gallstones or episodes of cholestasis of pregnancy were found in patients or parents. Children with missense mutations had a less severe disease and more often a beneficial effect of ursodeoxycholic acid therapy.

CONCLUSIONS

At least one third of the patients with a progressive familial intrahepatic cholestasis type 3 phenotype have a proven defect of MDR3. This gene defect should also be considered in adult liver diseases.

Association of sleep-wake habits in older people with changes in output of circadian pacemaker

Many elderly people complain of disturbed sleep patterns but there is not evidence that the need to sleep decreases with age; it seems rather that the timing and consolidation of sleep change. We tried to find out whether there is a concurrent change in the output of the circadian pacemaker with age. The phase and amplitude of the pacemaker's output were assessed by continuous measurement of the core body temperature during 40 h of sustained wakefulness under constant behavioural and environmental conditions. 27 young men (18-31 years) were compared with 21 older people (65-85 years; 11 men, 10 women); all were healthy and without sleep complaints. The mean amplitude of the endogenous circadian temperature oscillation (ECA) was 40% greater in young men than in the older group. Older men had a lower mean temperature ECA than older women. The minimum of the endogenous phase of the circadian temperature oscillation (ECP) occurred 1 h 52 min earlier in the older than in the young group. Customary bedtimes and waketimes were also earlier in the older group, as was their daily alertness peak. There was a close correlation between habitual waketime and temperature ECP in young men, which may lose precision with age, especially among women. These findings provide evidence for systematic age-related changes in the output of the human circadian pacemaker. We suggest that these changes may underlie the common complaints of sleep disturbance among elderly people. These changes could reflect the observed age-related deterioration of the hypothalamic nuclei that drive mammalian circadian rhythms.

Structure and expression of a new complementary DNA encoding the almost exclusive 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase in human adrenals and gonads

The 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta HSD) enzyme catalyzes the oxidation and isomerization of delta 5-3 beta-hydroxysteroid precursors into delta 4-ketosteroids, thus leading to the formation of all classes of steroid hormones. In addition, 3 beta HSD catalyzes the interconversion of 3 beta-hydroxy- and 3-keto-5 alpha-androstane steroids. Clinical observations in patients with 3 beta HSD deficiency as well as our recent data obtained by Southern blot analysis using a human placental 3 beta HSD cDNA (type I) as probe suggested the existence of multiple related 3 beta HSD isoenzymes. We now report the isolation and characterization of a second type of cDNA clone (arbitrarily designated type II) encoding 3 beta HSD after screening of a human adrenal lambda gt22A library. The nucleotide sequence of 1676 basepairs of human 3 beta HSD type II cDNA predicts a protein of 371 amino acids with a calculated molecular mass of 41,921 daltons, which displays 93.5% and 96.2% homology with human placental type I and rhesus macaque ovary 3 beta HSD deduced proteins, respectively. To characterize and compare the kinetic properties of the two isoenzymes, plasmids derived from pCMV and containing type I or type II 3 beta HSD full-length cDNA inserts were transiently expressed in HeLa human cervical carcinoma cells. In vitro incubation with NAD+ and 3H-labeled pregnenolone or dehydroepiandrosterone shows that the type I protein possesses a 3 beta HSD/delta 5-delta 4 isomerase activity higher than type II, with respective Km values of 0.24 vs. 1.2 microM for pregnenolone and 0.18 vs. 1.6 microM for dihydroepiandrosterone, while the specific activity of both types is equivalent. Moreover, incubation in the presence of NADH of homogenates from cells transfected with type I or type II 3 beta HSD indicates that dihydrotestosterone is converted into 5 alpha-androstane-3 beta, 17 beta-diol, with Km values of 0.26 and 2.7 microM, respectively. Ribonuclease protection assay using type I- and type II-specific cRNA probes revealed that type II transcripts are the almost exclusive 3 beta HSD mRNA species in the human adrenal gland, ovary, and testis, while type I transcripts correspond to the almost exclusive 3 beta HSD mRNA species in the placenta and skin and represent the predominantly expressed species in mammary gland tissue. The present data show for the first time that adrenals and gonads express a type of 3 beta HSD isoenzyme that is distinct from the type expressed in the placenta.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacterial expression of a mitochondrial cytochrome c. Trimethylation of lys72 in yeast iso-1-cytochrome c and the alkaline conformational transition

Saccharomyces cerevisiae iso-1-cytochrome c has been expressed in Escherichia coli by coexpression of the genes encoding the cytochrome (CYC1) and yeast cytochrome c heme lyase (CYC3). Construction of this expression system involved cloning the two genes in parallel into the vector pUC18 to give the plasmid pBPCYC1(wt)/3. Transcription was directed by two promoters, Lac and Trc, that were located upstream from CYC1. Both proteins were expressed in the cytoplasm of E. coli cells harboring the plasmid. Semianaerobic cultures grown in a fermentor produced 15 mg of recombinant iso-1-cytochrome c per liter of culture. Attempts to increase production by addition of IPTG suppressed the number of copies of the CYC1 gene within the population. Wild-type iso-1-cytochrome c expressed with pBPCYC1(wt)/3 in E. coli was compared to the same protein expressed in yeast. At neutral pH, the two proteins exhibit indistinguishable spectroscopic and physical (Tm, Em') characteristics. However, electrospray mass spectrometry revealed that the lysyl residue at position 72 is not trimethylated by E. coli as it is by S. cerevisiae. Interestingly, the pKa of the alkaline transition of the protein expressed in E. coli is approximately 0.6 pKa unit lower than that observed for the cytochrome expressed in yeast (8.5-8.7). 1H NMR spectroscopy of the bacterially expressed cytochrome collected at high pH revealed the presence of a third alkaline conformer that is not observed in the corresponding spectrum of the cytochrome expressed in yeast. These observations suggest that Lys72 can serve as an axial ligand to the heme iron of alkaline iso-1-ferricytochrome c if it is not modified posttranscriptionally to trimethyllysine.

Identification and sequence of the gene encoding cytochrome c heme lyase in the yeast Saccharomyces cerevisiae

Mitochondrial cytochrome c contains a heme group covalently attached through thioether linkages to two cysteinyl residues of the protein. We demonstrate here that the nuclear gene, CYC3, in the yeast Saccharomyces cerevisiae, encodes cytochrome c heme lyase (CCHL), the enzyme catalyzing the attachment of heme to apocytochrome c. Mitochondrial extracts from cyc3- mutants are deficient in CCHL activity compared with extracts from normal strains, whereas strains carrying multiple copies of the CYC3 gene exhibit high levels of the activity. The CYC3 gene was cloned by functional complementation of a cyc3- mutant using a previously isolated plasmid containing the gene PYK1, which is tightly linked to CYC3. An open reading frame encoding a protein of 269 amino acids was identified from the DNA sequence of a fragment encompassing the CYC3 gene, and the corresponding transcript shown to be approximately 0.9 kb in length. CCHL appears to be a single polypeptide chain which acts specifically on the two forms of cytochrome c, but not on cytochrome c1.

Defect of multidrug-resistance 3 gene expression in a subtype of progressive familial intrahepatic cholestasis

Disruption of the murine mdr2 (multidrug-resistance) gene, which encodes a phosphatidylcholine flippase, leads to a hepatic disorder because of loss of biliary phospholipid secretion. Among the hereditary human cholestasis, a subtype of progressive familial intrahepatic cholestasis with high gamma-glutamyltranspeptidase (GGT) serum activity shares histological, biochemical, and genetic features with mice lacking mdr2 gene expression (mdr2 -/- mice). No MDR3 (human mdr2 homolog) messenger RNA (mRNA) was detected by Northern blotting in the liver of a patient suffering from this form of PFIC, and the biliary phospholipid level in a second patient was substantially decreased. Thus, the absence of the MDR3 P-glycoprotein may be responsible for this type of PFIC, which, as in the murine model, may be due to a toxic effect of bile acids on the biliary epithelium in absence of biliary phospholipids.

Circadian and homeostatic sleep regulation in morningness-eveningness

Morningness-eveningness has been associated with the entrained circadian phase. However, we recently identified morning and evening types having similar circadian phases. In this paper, we compared parameters of slow-wave activity (SWA) decay in non-rapid-eye-movement (NREM) sleep between these two subgroups to test the hypothesis that differences in the dynamics of nocturnal homeostatic sleep pressure could explain differences in sleep timing preference. Twelve morning-type subjects and 12 evening-type subjects with evening types (aged 19-34 years) selected using the Morningness-Eveningness Questionnaire were further classified according to the phase of their dim light melatonin onset (DLMO). The six morning types with the earliest DLMO were compared to the six evening types with the latest DLMO ('extreme' phases), and the six morning types with the latest DLMO were compared to the six evening types with the earliest DLMO ('intermediate' phases). Subjects slept according to their preferred sleep schedule. Spectral activity in four midline derivations (Fz, Cz, Pz, Oz) was calculated in NREM sleep and an exponential decay function was applied on SWA data averaged per sleep cycle. In the subjects with intermediate circadian phases, both initial level and decay rate of SWA in Fz were significantly higher in morning than in evening types. No difference appeared between chronotypes of extreme circadian phases. There was no correlation between individual estimates of SWA decay and DLMO. These results support the hypothesis that chronotype can originate from differences in the dissipation of sleep pressure and that homeostatic and circadian processes influence the sleep schedule preference independently.

Prospective evaluation of endoscopic ultrasonography and microscopic examination of duodenal bile in the diagnosis of cholecystolithiasis in 45 patients with normal conventional ultrasonography

The aim of this study was to prospectively evaluate endoscopic ultrasonography and microscopic examination of duodenal bile in the diagnosis of cholecystolithiasis not detected by conventional ultrasonography. Forty five consecutive patients (26 females, 19 males, mean age: 50 years) with suspected cholecystolithiasis and at least two normal transcutaneous ultrasonography examinations were included. Endoscopic ultrasonographic criteria for the diagnosis of cholecystolithiasis were the presence of stones with or without acoustic shadowing or sludge. Criteria of microscopic examination of bile were cholesterol or bilirubinate crystals or spheroliths. Thirty three patients underwent cholecystectomy and lithiasis was found in gall bladder bile in 24. Twelve patients who were not operated on and were followed up (median: 17 months), had no evidence of cholecystolithiasis. Endoscopic ultrasonography and duodenal bile examination were 96% and 67% sensitive, respectively (p < 0.03). The specificity was not different (86 and 91%, respectively). None of the 16 patients with negative results in both procedures had evidence of cholecystolithiasis. It was found that for the diagnosis of cholecystolithiasis in patients with normal conventional ultrasonography, the sensitivity of endoscopic ultrasonography is higher than that of microscopic examination of duodenal bile. If endoscopic ultrasonography and microscopic examination of duodenal bile are negative, the risk of underdiagnosing cholecystolithiasis is negligible.

Profile of 24-h light exposure and circadian phase of melatonin secretion in night workers

Light exposure was measured in 30 permanent night nurses to determine if specific light/dark profiles could be associated with a better circadian adaptation. Circadian adaptation was defined as a significant shift in the timing of the episode of melatonin secretion into the daytime. Light exposure was continuously recorded with ambulatory wrist monitors for 56 h, including 3 consecutive nights of work. Participants were then admitted to the laboratory for 24 h where urine was collected every 2 h under dim light for the determination of 6-sulphatoxymelatonin concentration. Cosinor analysis was used to estimate the phase position of the episode of melatonin secretion. Five participants showed a circadian adaptation by phase delay ("delayed participants") and 3 participants showed a circadian adaptation by phase advance ("advanced participants"). The other 22 participants had a timing of melatonin secretion typical of day-oriented people ("nonshifters"). There was no significant difference between the 3 groups for total light exposure or for bright light exposure in the morning when traveling home. However, the 24-h profiles of light exposure were very distinctive. The timing of the main sleep episode was associated with the timing of light exposure. Delayed participants, however, slept in darker bedrooms, and this had a major impact on their profile of light/dark exposure. Delayed and advanced participants scored as evening and morning types, respectively, on a morningness-eveningness scale. This observation suggests that circadian phase prior to night work may contribute to the initial step toward circadian adaptation, later reinforced by specific patterns of light exposure.

Seasonal and diurnal patterns of human illumination under natural conditions

Little is known about the natural pattern of seasonal and diurnal illumination to which normal people are exposed, especially in northern latitudes. In this study, ambient illumination of normal volunteers living at a latitude of 45 degrees 31' N was recorded with ambulatory photosensors worn for 5 to 6 days in winter and summer. Results from 12 normal subjects (6 men, 6 women) aged 18 to 35 years were included in the analyses. The mean daily duration of time awake was similar in both seasons: 14.6h in the summer and 14.9h in the winter. However, the phase of the sleep-wake cycle was advanced in the summer compared to the winter, as shown by an earlier average waketime and bedtime in the summer. Illumination recorded by the ambulatory monitor between waketime and bedtime was categorized according to four ranges of light intensities: very dim (< 1 lux), dim (1-100 lux), moderate (100-1000 lux), and bright (> 1000 lux) illumination. There was no seasonal difference for the time spent in illumination lower than 1000 lux, but the duration of daily exposure to bright light averaged 2.6h in the summer compared to only 0.4h in the winter (p = 0.0004). To evaluate the diurnal distribution of ambient illumination, time spent awake was divided into four time intervals: morning (waketime to 12:00), afternoon (12:00 to 16:00), early evening (16:00 to 20:00), and late evening (20:00 to bedtime). Except for late evening, the time spent in bright illumination was significantly longer during the summer for all time intervals, but the relative distribution of bright light exposure throughout the day was the same in both seasons. The subjects spent more than 50% of their time awake in illumination dimmer than 100 lux, even in the summer. More naturalistic studies are needed to determine whether very short exposure to bright light or longer exposure to light of moderate intensity (100-1000 lux) are sufficient to maintain circadian entrainment and euthymia in normal young subjects.

Coculture of embryos on Vero cells and transfer of blastocysts in humans

Preliminary results are presented concerning the first clinical application of cocultures of human embryos. In the experimental group, the embryos were cultured and transferred on day 5 post-insemination. Blastocyst formation was not dependent upon the stimulation regimen. Long term or ultrashort stimulation of the ovaries after gonadotrophin releasing hormone analogue gave 55-60% blastocyst formation. Serum was not necessary to obtain blastocysts. When the embryos were cocultured, we observed an increase in the implantation rates per embryo in the pregnant patients. However, a real increase in the pregnancy rate per transfer was observed in a population of patients who had had repeated failures of embryo transfer. This observation is discussed as possibly bypassing an effect of uterine motility, but the overall beneficial effect has to be assessed in a double blind randomized study. It is probable that improvements will not be observed for all the indications for in vitro fertilization.

Structure of the human type II 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) gene: adrenal and gonadal specificity

While classical 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase deficiency (3 beta-HSD) is a known cause of adrenal hyperplasia resulting in ambiguous genitalia and adrenal insufficiency at birth, nonclassical or late-onset 3 beta-HSD deficiency is found in an important proportion of women with androgen excess. We have previously isolated and sequenced the cDNA and gene for the human type I 3 beta-HSD, which represents the main species expressed in the placenta and skin. Recently, we isolated, sequenced, and expressed the functional cDNA encoding type II 3 beta-HSD, which is the predominant 3 beta-HSD expressed in human adrenals and gonads. The present study describes the isolation and complete sequence of the corresponding type II 3 beta-HSD gene, which is the form most likely responsible for human 3 beta-HSD deficiency. The structural gene contains four exons of 57, 231, 165, and 1,214 bp, respectively, separated by introns of 128, 3,383, and 2,162 bp. DNA sequence analysis of the 5'-flanking region reveals the existence of two putative TATA boxes situated 28 and 140 nucleotides upstream from the transcription start site whereas two putative CAAT boxes are located 57 and 38 nucleotides upstream from the TATA boxes, respectively. A restriction fragment length pattern specific for each gene has been characterized. The present findings should provide the tools required for detailed analysis of the molecular basis of 3 beta-HSD deficiency as well as of normal sex steroid biosynthesis.

A study of the dynamic interactions between sleep EEG and heart rate variability in healthy young men

OBJECTIVE

We investigated the interactions between heart rate variability and sleep electroencephalogram power spectra.

METHODS

Heart rate and sleep electroencephalogram signals were recorded in 8 healthy young men. Spectral analysis was applied to electrocardiogram and electroencephalogram recordings. Spectral components of RR intervals were studied across sleep stages. The cross-spectrum maximum was determined as well as coherencies, gains and phase shifts between normalized high frequency of RR intervals and all electroencephalographic frequency bands, calculated over the first 3 NREM-REM cycles.

RESULTS

RR intervals increased from awake to NREM and decreased during REM. Normalized low frequency decreased from awake to NREM and increased during REM while normalized high frequency evolved conversely. Low to high frequency ratio developed in opposition to RR intervals. Coherencies between normalized high frequency and power spectra were high for all bands. The gain was highest for delta band. Phase shift between normalized high frequency and delta differed from zero and modifications in normalized high frequency preceded changes in delta by 41+/-14 degrees.

CONCLUSIONS

Our study demonstrates that: (1) all electroencephalographic power bands are linked to normalized high frequency; (2) modifications in cardiac vagal activity show predominantly parallel changes and precede changes in delta band by a phase shift corresponding to a lead of 12+/-5 min.

A facile method for high-throughput co-expression of protein pairs

We developed a method to co-express protein pairs from collections of otherwise identical Escherichia coli plasmids expressing different ORFs by incorporating a 61-nucleotide sequence (LINK) into the plasmid to allow generation of tandem plasmids. Tandem plasmids are formed in a ligation-independent manner, propagate efficiently, and produce protein pairs in high quantities. This greatly facilitates co-expression for structural genomics projects that produce thousands of clones bearing identical origins and antibiotic markers.

Spatial learning, exploration, anxiety, and motor coordination in female APP23 transgenic mice with the Swedish mutation

Transgenic mice overexpressing the betaAPP gene with the Swedish mutation under the control of the murine thy-1 promoter show Alzheimer-like characteristics including the accumulation of Abeta protein in the cerebral cortex. Female 16-month-old APP23 transgenic mice were compared to age-matched non-transgenic mice in behavioral tests measuring spatial learning, exploration of environmental stimuli, anxiety, and motor coordination. APP23 transgenic mice had fewer fast ambulatory movements, either fast or slow stereotypy movements, and slow rears in a photocell activity chamber. The acquisition of spatial learning in the Morris water maze was impaired in APP23 transgenic mice, but not during the probe test or while swimming towards a visible platform. Neither were there intergroup differences in tests of anxiety or motor coordination. These results indicate that a learning deficit and hypoactivity, concordant with the early stages of Alzheimer's disease, characterize this mouse model with Abeta accumulation.