Medial temporal lobe atrophy on MRI scans and the diagnosis of Alzheimer disease

BACKGROUND

Despite convenience, accessibility, and strong correlation to severity of Alzheimer disease (AD) pathology, medial temporal lobe atrophy (MTA) has not been used as a criterion in the diagnosis of prodromal and probable AD.

METHODS

Using a newly validated visual rating system, mean MTA scores of three bilateral medial temporal lobe structures were compared for subjects with no cognitive impairment (NCI) (n = 117), nonamnestic mild cognitive impairment (MCI) (n = 46), amnestic MCI (n = 45), and probable AD (n = 53). Correlations between MTA scores and neuropsychological test scores at baseline, and predictors of change in diagnosis at 1-year follow-up were evaluated.

RESULTS

With NCI as the reference group, a mean MTA cut score of 1.33 yielded an optimal sensitivity/specificity of 85%/82% for probable AD subjects and 80%/82% for amnestic MCI subjects. MTA and Clinical Dementia Rating Sum of Boxes scores at baseline were independent and additive predictors of diagnosis at baseline, and of transition from NCI to MCI or from MCI to dementia at 1-year follow-up.

CONCLUSION

Medial temporal lobe atrophy (MTA) scores 1) distinguish probable Alzheimer disease (AD) and amnestic mild cognitive impairment (MCI) subjects from nonamnestic MCI and no cognitive impairment (NCI) subjects, 2) help predict diagnosis at baseline, and 3) predict transition from NCI to MCI and from MCI to probable AD. MTA scores should be used as a criterion in the clinical diagnosis of AD.

Polyarginines are potent furin inhibitors

The ubiquitous serine endoprotease furin has been implicated in the activation of bacterial toxins and viral glycoproteins as well as in the metastatic progression of certain tumors. Although high molecular mass bioengineered serpin inhibitors have been well characterized, no small nontoxic nanomolar inhibitors have been reported to date. Here we describe the identification of such inhibitors using positional scanning amidated and acetylated synthetic l- and d-hexapeptide combinatorial libraries. The results indicated that l-Arg or l-Lys in all positions generated the most potent inhibitors. However, further investigation revealed that the peptide terminating groups hindered inhibition. Consequently, a series of non-amidated and acetylated polyarginines was synthesized. The most potent inhibitor identified, nona-l-arginine, had a K(i) for furin of 40 nm. The K(i) values for the related convertases PACE4 and prohormone convertase-1 (PC1) were 110 nm and 2.5 microm, respectively. Although nona-l-arginine was cleaved by furin, the major products after a 6-h incubation at 37 degrees C were hexa- and hepta-l-arginines, both of which retained the great majority of their potency and specificity against furin. Hexa-d-arginine was as potent and specific a furin inhibitor as hexa-l-arginine (K(i) values of hexa-d-arginine: 106 nm, 580 nm, and 13.2 microm for furin, PACE4, and PC1, respectively). PC2 was not inhibited by any polyarginine tested; indeed, PC2 showed an increase in activity of up to 140% of the control in the presence of l-polyarginines. Data are also presented that show extended subsite recognition by furin and PC2. Whereas N-terminal acetylation was found to reduce the inhibitory potency of the l-hexapeptide LLRVKR against furin 8-fold, C-terminal amidation reduced the potency < 2-fold. Conversely, N-terminal acetylation increased the potency against PC2 nearly 3-fold, whereas C-terminal amidation of the same peptide increased the potency by a factor of 1.6. Our data indicate that non-acetylated, poly-d-arginine-derived molecules may represent excellent lead compounds for the development of therapeutically useful furin inhibitors.

The bidirectional hydrogenase of Synechocystis sp. PCC 6803 works as an electron valve during photosynthesis

The activity of the bidirectional hydrogenase of the cyanobacterium Synechocystis sp. PCC 6803 was found not to be regulated in parallel to respiration but to photosynthesis. A mutant with a deletion in the large hydrogenase subunit gene (hoxH), which contains the active site, was impaired in the oxidation of photosystem I (PSI) when illuminated with light, which excites either PSI alone or both photosystems. The fluorescence of photosystem II (PSII) of this mutant was higher than that of wild-type cells. The transcript level of the photosynthetic genes psbA, psaA and petB was found to be different in the hydrogenase-free mutant cells compared to wild-type cells, which indicates that the hydrogenase has an effect on the regulation of these genes. Collectively, these results suggest that the bidirectional hydrogenase functions as a valve for low-potential electrons generated during the light reaction of photosynthesis, thus preventing a slowing down of electron transport. This conclusion is supported by growth curves demonstrating that the mutant cells need more time to adapt to changing light intensities. Investigations of the wild-type and deltahoxH strains strongly suggest that Synechocystis contains only the bidirectional hydrogenase, which seems to be essentially insensitive to oxygen.

Inhibition of furin by polyarginine-containing peptides: nanomolar inhibition by nona-D-arginine

Polyarginine-containing peptides represent potent inhibitors of furin, a mammalian endoprotease that plays an important role in metabolism, activation of pathogenic toxins, and viral proliferation. The therapeutic use of D-polyarginines is especially interesting because they are not cleaved by furin and possess inhibitory potency almost equal to L-polyarginines. In this study we attempted to determine the important elements within polyarginines that contribute to effective inhibition. Structure-function analyses of polyarginine peptides showed that inhibition by polyarginine-containing peptides appeared to depend on the total number of basic charges of the positively charged inhibitors bound to the negatively charged substrate binding pocket; peptide positioning did not appear to be rigorously determined. Screening of L- and D-decapeptide positional scanning combinatorial peptide libraries indicated a preference for basic residues in nearly all positions, similar to previous results with hexapeptide libraries. Length and terminal modification studies showed that the most potent D-polyarginine tested was nona-D-arginine (D9R) amide with a K(i) of 1.3 nm. D9R amide was shown to protect RAW264.7 cells against anthrax toxemia with an IC(50) of 3.7 microm. Because of its high stability, specificity, low toxicity, small molecular weight, and extremely low K(i) against furin, D9R amide or its derivatives may represent promising compounds for therapeutic use.

Mesoscopic atomic entanglement for precision measurements beyond the standard quantum limit

Squeezing of quantum fluctuations by means of entanglement is a well-recognized goal in the field of quantum information science and precision measurements. In particular, squeezing the fluctuations via entanglement between 2-level atoms can improve the precision of sensing, clocks, metrology, and spectroscopy. Here, we demonstrate 3.4 dB of metrologically relevant squeezing and entanglement for greater, similar 10(5) cold caesium atoms via a quantum nondemolition (QND) measurement on the atom clock levels. We show that there is an optimal degree of decoherence induced by the quantum measurement which maximizes the generated entanglement. A 2-color QND scheme used in this paper is shown to have a number of advantages for entanglement generation as compared with a single-color QND measurement.

Sequence analysis of an operon of a NAD(P)-reducing nickel hydrogenase from the cyanobacterium Synechocystis sp. PCC 6803 gives additional evidence for direct coupling of the enzyme to NAD(P)H-dehydrogenase (complex I)

The sequence of a NAD(P)-reducing hydrogenase operon of Synechocystis sp. PCC 6803 containing genes for a small and a large hydrogenase subunit and six additional ORFs was determined. Until now only 11 of the 14 polypeptides of the NADH-dehydrogenase of E. coli were found in Synechocystis. By sequence homologies we suggest that the missing subunits of the peripheral part of the dehydrogenase, containing most of the FeS-clusters, are encoded by three ORFs of this operon. This hypothesis is discussed in relation to the NAD(P)-reducing hydrogenase of Synechocystis.

A review of the utility of soluble peptide combinatorial libraries

This paper reviews the preparation and use of soluble synthetic combinatorial libraries (SCLs) made up of millions of peptide and nonpeptide sequences for the identification of highly active individual compounds. First presented in 1991, SCLs have been prepared in a number of different lengths and formats, and are composed entirely of L-, D-, and unnatural amino acids. Also, existing peptide libraries have been chemically transformed to yield large diversities of nonpeptidic compounds. This review encompasses the published work from this laboratory using SCLs for the identification of antigenic sequences recognized by monoclonal antibodies, novel peptide agonists and antagonists to opioid receptors, new trypsin inhibitors, novel antibacterials, and compounds that inhibit melittin's hemolytic activity. SCLs offer a fundamental, practical advance in the study of interactions between peptide and nonpeptide sequences and their biochemical or pharmacological targets.

Transforming growth factor beta 1 is an inducer of erythroid differentiation

Normal human bone marrow cells, highly enriched for burst-forming units-erythroid (BFU-E), were cultured in serum-free medium, in the presence and absence of various factors, to investigate the mechanisms involved in regulating erythroid differentiation. In cultures containing interleukin 3 (IL-3), Steel factor (SF), and erythropoietin (Ep), benzidine-positive erythroblasts first became detectable on day 6. Their numbers then rapidly increased until, by day 16, > 99% of the cells, which were 20,000-fold amplified over input numbers, were benzidine-positive. It is interesting to note that omission of either SF or Ep from this assay markedly enhanced the rate of differentiation and reduced total cell numbers, whereas omission of IL-3 had no effect on the rate of differentiation and only slightly reduced cell numbers. Of various agents tested, the most potent erythroid differentiation inducer (and inhibitor of cell proliferation) was found to be transforming growth factor beta 1 (TGF-beta 1). This cytokine stimulated both the rapid appearance of hemoglobin-positive cells and an early cessation of cell proliferation. Using fluorescently tagged antibodies to glycophorin A and fluorescence-activated cell sorter (FACS) analysis, this phenomenon was shown to be due to an early induction of erythroid differentiation rather than an aberrant production of hemoglobin. Methylcellulose assays indicated that the well-documented reduction of BFU-E colony numbers observed with TGF-beta 1 may actually be due to a TGF-beta 1-induced "conversion" of BFU-E into colony-forming units-erythroid (CFU-E). Thus, in vivo, TGF-beta 1 might serve, in part, to decrease the number of mature erythrocytes by stimulating BFU-E to skip a number of cell divisions and differentiate early.

Hospital-based comprehensive cardiac rehabilitation versus usual care among patients with congestive heart failure, ischemic heart disease, or high risk of ischemic heart disease: 12-month results of a randomized clinical trial

BACKGROUND

Current guidelines broadly recommend comprehensive cardiac rehabilitation (CCR), although evidence for this is still limited. We investigated the 12-month effect of hospital-based CCR versus usual care (UC) for a broadly defined group of cardiac patients within the modern therapeutic era of cardiology.

METHODS

We conducted a centrally randomized single-center clinical trial with blinded assessment of the primary outcome: registry-based composite of total mortality, myocardial infarction, or acute first-time readmission due to heart disease. Other outcomes were hospitalization, risk profile, and quality of life. The trial included 770 participants (20-94 years) with congestive heart failure (12%), ischemic heart disease (58%), or high risk of ischemic heart disease (30%). Comprehensive cardiac rehabilitation is composed of 6 weeks of intensive intervention and systematic follow-up for 10.5 months.

RESULTS

We randomized 380 patients to CCR versus 390 to UC. Randomization was well balanced. The primary outcome occurred in 31% of both groups (relative risk 0.96, 95% confidence interval 0.78-1.26). Compared with the UC group, CCR significantly reduced length of stay by 15% (95% confidence interval 1.1%-27.1%, P = .04), mean number of cardiac risk factors above target (4.5 vs 4.1, P = .01), patients with systolic blood pressure below target (P = .003), physically inactivity (P = .01), and unhealthy dietary habits (P = .0003). Short-Form-36 and Hospital Anxiety and Depression Scale did not differ significantly.

CONCLUSION

At 12 months, the CCR and UC groups did not differ regarding the primary composite outcome. Comprehensive cardiac rehabilitation significantly reduced length of hospital stay and improved cardiac risk factors.

Identification of inhibitors of prohormone convertases 1 and 2 using a peptide combinatorial library

A positional scanning synthetic peptide combinatorial library containing approximately 52 million hexapeptides was used to identify potential inhibitory peptides for recombinant mouse prohormone convertase 1 (PC1) and PC2 and to provide information on the specificity of these enzymes. The library surveys revealed that a P6 Leu, a P4 Arg, a P2 Lys, and a P1 Arg were most inhibitory against PC1, and a P6 Ile and a P4 Arg were most inhibitory against PC2. Using information derived from the library surveys, hexapeptide sets were synthesized and screened for inhibition of PC1 and PC2. The data obtained revealed the preference of both enzymes for a P3 Val. At P5, many substitutions were well tolerated. PC1 and PC2 proved to differ mainly in the selectivity of their S6 subsites. In PC1, this subsite displayed a strong preference toward occupation by Leu; the Ki value for peptide Ac-Leu-Leu-Arg-Val-Lys-Arg-NH2 was 28 times lower than that for peptide Ac-Ile-Ile-Arg-Val-Lys-Arg-NH2. In contrast, PC2 discriminated little between Leu and Ile at P6, as evidenced by the small (1.5-fold) difference in Ki values for these two peptides. Several hexapeptides synthesized as a result of the screen were found to represent potent inhibitors of PC2 (with Ki values in the submicromolar range) and, particularly, of PC1 (with Ki values in the low nanomolar range). The most potent inhibitor, Ac-Leu-Leu-Arg-Val-Lys-Arg-NH2, proved to be the same peptide for both enzymes and inhibited PC1 and PC2 in a competitive, fast-binding manner with Ki values of 3.2 and 360 nM, respectively. The four most potent peptide inhibitors of PC1 and PC2 were also tested against soluble human furin and found to exhibit a different rank order of inhibition; for example, Ac-Leu-Leu-Arg-Val-Lys-Arg-NH2 was 440-fold less potent against furin than against PC1, with a Ki of 1400 nM.

Short polybasic peptide sequences are potent inhibitors of PC5/6 and PC7: Use of positional scanning-synthetic peptide combinatorial libraries as a tool for the optimization of inhibitory sequences

Positional scanning-synthetic peptide combinatorial libraries (PS-SPCLs) are powerful molecular tools to identify enzyme substrate and potent inhibitory sequences and also to provide crucial information about active site determinants. PS-SPCLs have been surveyed for furin, proprotein convertase (PC)2, PC1/3, and PACE4 and proven efficient to identify potent peptidyl inhibitors in the low nanomolar range for furin and PC1/3. We report herein the screenings of nonamidated and acetylated hexapeptide PS-SPCLs for PC5/6A and PC7. The L-configuration library surveys distinctively revealed that L-Arg, L-Lys, and sometimes L-His in all six positions would generate the most potent inhibitors for both enzymes. Based on this clear polybasic preference, L-poly-Arg peptides ranging from four to nine residues were assayed. Inhibitory potency of these polybasic peptides increased with chain length, making nona-l-Arg a potent nanomolar inhibitor of PC5/6A and PC7 (Ki of 150 and 120 nM). PC5/6 and PC7 inhibition by nona-l-arginine was equivalent to that of furin (Ki of 114 nM) (J Biol Chem 275: 36741-36749, 2000). Nona-d-arginine was a more potent inhibitor of PC5/6 and PC7 than its levorotatory version (Ki of 19 and 81 nM), reminiscent of furin (Ki of 1.3 nM) (J Biol Chem 279:36788-36794, 2004). Our data indicate that certain poly-arginine peptides represent potent inhibitors targeting PCs of the constitutive secretory pathway (furin, PC5/6, and PC7). We conclude that basic residues within PC peptide inhibitors might be responsible for targeting PCs in general and for inhibitory potency, but that select amino acid changes will be necessary to acquire true specificity toward a single PC.

Vancomycin-resistant Pediococcus acidilactici: nine cases of bacteremia

Pediococci, vancomycin-resistant gram-positive cocci, have been isolated from human specimens, but an association with clinical illness has not been established. Clinical and epidemiologic data were obtained on nine patients who had Pediococcus acidilactici isolated from blood. Patients were eight elderly adults with complicated medical problems and one infant with congenital jejunoileal atresia. Seven patients were hospitalized before P. acidilactici was isolated. Eight had received multiple antibiotics; however, only two had received vancomycin. In all cases there was a delay in correct bacterial identification, and the significance of the isolate was uncertain. There was no clearly identified syndrome associated with P. acidilactici bacteremia. All eight adults had fever and six had pneumonia potentially attributable to other causes. The findings underscore the importance of proper identification of vancomycin-resistant gram-positive cocci. P. acidilactici may be an opportunistic pathogen in severely compromised hosts; however, further observations are necessary to clarify its role in human disease.

Prevalence of impaired left ventricular systolic function and heart failure in a middle aged and elderly urban population segment of Copenhagen

OBJECTIVE

To assess the prevalence of impaired left ventricular systolic function and manifest heart failure in a general population aged 50-89 years.

DESIGN

In this cross sectional survey, participants filled in a heart failure questionnaire. ECG, blood tests, and echocardiography were performed.

SETTING

The study population was recruited from general practitioners situated in the same urban area and examined in a university hospital in Copenhagen, Denmark.

PARTICIPANTS

764 participants (432 women and 332 men, median (SD) age 66 (11) years) participated. The study population was stratified to include a minimum of 150 persons in each age decade.

MAIN OUTCOME MEASURES

Prevalence of impaired systolic function and manifest heart failure.

RESULTS

The prevalence of systolic dysfunction (left ventricular ejection fraction < or = 40%) was more than twice as high among men (7.6%) as among women (2.6%). In the male population systolic heart failure (left ventricular ejection fraction < or = 40% and symptoms) was found in 1.8% of the 50-59 years age group and approximately doubled for each age decade to reach 13.9% in octogenarians. Among women systolic dysfunction increased from 0.8% to 4.3% in the same age groups. Asymptomatic cases accounted for 44.0% of all cases of systolic dysfunction in the male population and only 9.1% in the female population.

CONCLUSIONS

In this age controlled population study impaired left ventricular systolic function and heart failure increased substantially with age and was more than twice as frequent among men as among women. Asymptomatic left ventricular dysfunction occurred more frequently in men than in women and was less prevalent with increasing age.

The effects of noncollagenous matrix proteins on hydroxyapatite formation and proliferation in a collagen gel system

The effects of several noncollagenous matrix proteins on hydroxyapatite formation and growth were studied in a dynamic collagen gel system. In this system growth plate proteoglycan aggregates at concentrations of 1-10 micrograms/ml were effective inhibitors, desulfated aggregates from brachymorphic mice were less effective. Phosphophoryn at 1-100 micrograms/ml had no effect on formation; 60-120 micrograms/ml retarded mineral growth. Type X collagen at concentrations of 50-300 micrograms/ml had no effect on formation or growth.

Association of white matter hyperintensity measurements on brain MR imaging with cognitive status, medial temporal atrophy, and cardiovascular risk factors

BACKGROUND AND PURPOSE

White matter hyperintensities (WMHs) are frequently characterized as markers of cerebrovascular disease, whereas medial temporal atrophy (MTA) is a recognized marker of Alzheimer disease (AD). Our purpose was to test the reliability of a visual rating system (VRS) in evaluating WMHs and MTA and in distinguishing healthy from cognitively impaired subjects.

MATERIALS AND METHODS

Subjects (n = 192) enrolled in the Florida Alzheimer's Disease Research Center were diagnosed with no cognitive impairment, nonamnestic mild cognitive impairment (na-MCI), amnestic MCI (a-MCI), or probable AD. The severity of WMHs was assessed on T2-weighted fluid-attenuated inversion recovery axial MR images, and the severity of MTA was evaluated on 1.5-mm-thick coronal MR images by using a computer-based visual rating system. Cardiovascular risk factor scores were calculated as the sum of 10 independent cardiovascular risk factors.

RESULTS

WMH and MTA scores were greater in subjects with probable AD, relative to those with no cognitive impairment and na-MCI. MTA scores differentiated subjects with a-MCI from those with no cognitive impairment and na-MCI. The total WMH score was significantly related to MTA (r = 0.39; P < .001) but not to cardiovascular risk factor scores (r = 0.07; P = not significant). The overall correct classification rate of probable AD versus no cognitive impairment by using MTA scores was 81.8%, improving to 86.5% when combined with WMH scores.

CONCLUSIONS

Both MTA and WMH scores distinguished subjects with no cognitive impairment and probable AD. Combining MTA and WMH scores improved the correct classification rate, whereas WMH scores were significantly related to MTA scores, but not to cardiovascular risk factor scores. This finding suggests that among subjects with a-MCI and probable AD, WMHs on MR images are primarily associated with neurodegenerative disease.

Assessment of cardiac function in marathon runners by graphic noninvasive techniques

The volume overload type of heart often observed in endurance athletes, was simulate a diseased heart. We used a battery of noninvasive graphic techniques, i.e., echocardiogram, apexcardiogram, carotid pulse, electrocardiogram, vectorcardiogram, phonocardiogram, systolic time intervals, and treadmill stress testing in 12 professional marathon runners, mean age 33.8 +/- 11.1. Twenty nonathletes matched for age, height, sex, and weight served as a control group. Left ventricular (LV) end-diastolic dimension in marathon runners averaged 5.53 +/- 0.5 cm compared to 4.81 +/- 0.04 cm in nonathletes (p less than 0.001), LV end-diastolic volume was 172.69 +/- 43.3 ml compared to 113.57 +/- 30.41 ml in nonathletes (p less than 0.001), stroke volume was 122.27 +/- 32.8 ml compared to 78.42 +/- 20.44 ml in non-athletes (p less than 0.001), the thickness of the posterior LV wall was 1.0 +/- 0.2 cm compared to 0.7 +/- 0.1 cm in nonathletes (p less than 0.001), and LV mass was significantly increased, 212.43 +/- 55.8 g compared to 123.48 +/- 24.54 g in non-athletes (p less than 0.01). Left atrium and aortic root were also relatively larger in athletes (p less than 0.01). Right ventricular end-diastolic dimension was enlarged in marathon runners (2.02 +/- 0.65 cm). No statistically significant differences were noted in ejection fraction, percentage of internal diameter shortening (% delta D) and PEP/LVET. The carotid tracing had a bisferiens pulse in five marathon runners. The apexcardiogram showed a bifid systolic thrust in three and absence of abnormal A wave. These abnormalities were related to the overload type of heart as proven by echocardiogram. "Early repolarization syndrome" (abnormal RS-T segment elevation) and notched T waves in ECG had a counterpart a semilunar configuration in the VCG. Three athletes met ECG criteria and one met VCG criteria of LVH. The treadmill exercise ECG was negative in all 12 athletes. Biventricular enlargement and increased left ventricular mass are present in the marathon runner's heart. Myocardial contractility at rest was, however, not statistically different from nonathletes.

Basal and exercise-induced neuroendocrine activation in patients with heart failure and in normal subjects

BACKGROUND

Neuroendocrine activation is a pathophysiological response and an important prognostic marker in patients with chronic heart failure (CHF). Although chronic activation is well described, data on the responsiveness of the hormone systems are more limited. Most previous studies have looked at activation during maximal exercise, whereas we believe that activation at a submaximal level might be more pathophysiologically relevant.

AIM

To compare exercise-induced neurohormonal activation between CHF patients and normal subjects using the same relative and submaximal workload.

SUBJECTS

Twenty-three newly-diagnosed CHF patients and 18 age- and gender-matched healthy subjects were exercised at two workloads, which were calculated to correspond to 50 and 75% of each individual's heart rate response.

RESULTS

In CHF patients, baseline levels of ANP, BNP, AVP, PRA and ET-1 were elevated compared to healthy subjects. Exercise induced an increase in ANP, A and NA in both CHF patients and in normal subjects, however BNP was only increased in CHF patients and not in normal subjects.

CONCLUSION

When CHF patients exercise at the same relative and submaximal level as age-matched healthy subjects, the relative increases in ANP, A and NA were similar, however, BNP levels only increased in the CHF group.

Heparin-induced thrombocytopenia and thrombosis: reversal with streptokinase. A case report and review of literature

Heparin-induced thrombocytopenia and thrombosis is associated with a significant incidence of morbidity and mortality. Prompt recognition of this complication and immediate withdrawal of heparin therapy are imperative. This report describes a case of heparin-induced thrombosis and thrombocytopenia with major vascular insufficiency of the extremities. This is the first reported instance of the use of intravenous streptokinase for the treatment of heparin-induced venous thrombosis.